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Materials, Volume 17, Issue 11 (June-1 2024) – 318 articles

Cover Story (view full-size image): Semiconductor photocatalysis is one of the important methods for treating organic dyes. In order to reduce the carrier recombination rate and enhance photocatalytic activity, ZnO was modified with V2C MXene with a large specific surface area to construct ZnO/MXene hybrids through electrostatic self-assembly for the degradation of MB. Herein, the modification of V2C MXene can increase the specific surface area to provide more sites for MB adsorption, widen the sunlight adsorption range to produce good photothermal effect, and facilitate the transfer of photogenerated carriers in ZnO to promote the reaction of more photogenerated carriers with MB. View this paper
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45 pages, 38405 KiB  
Review
Bulk MgB2 Superconducting Materials: Technology, Properties, and Applications
by Tetiana Prikhna, Vladimir Sokolovsky and Viktor Moshchil
Materials 2024, 17(11), 2787; https://doi.org/10.3390/ma17112787 - 6 Jun 2024
Viewed by 1628
Abstract
The intensive development of hydrogen technologies has made very promising applications of one of the cheapest and easily produced bulk MgB2-based superconductors. These materials are capable of operating effectively at liquid hydrogen temperatures (around 20 K) and are used as elements [...] Read more.
The intensive development of hydrogen technologies has made very promising applications of one of the cheapest and easily produced bulk MgB2-based superconductors. These materials are capable of operating effectively at liquid hydrogen temperatures (around 20 K) and are used as elements in various devices, such as magnets, magnetic bearings, fault current limiters, electrical motors, and generators. These applications require mechanically and chemically stable materials with high superconducting characteristics. This review considers the results of superconducting and structural property studies of MgB2-based bulk materials prepared under different pressure–temperature conditions using different promising methods: hot pressing (30 MPa), spark plasma sintering (16–96 MPa), and high quasi-hydrostatic pressures (2 GPa). Much attention has been paid to the study of the correlation between the manufacturing pressure–temperature conditions and superconducting characteristics. The influence of the amount and distribution of oxygen impurity and an excess of boron on superconducting characteristics is analyzed. The dependence of superconducting characteristics on the various additions and changes in material structure caused by these additions are discussed. It is shown that different production conditions and additions improve the superconducting MgB2 bulk properties for various ranges of temperature and magnetic fields, and the optimal technology may be selected according to the application requirements. We briefly discuss the possible applications of MgB2 superconductors in devices, such as fault current limiters and electric machines. Full article
(This article belongs to the Section Advanced and Functional Ceramics and Glasses)
►▼ Show Figures

Figure 1

Figure 1
<p>Dependences of critical current density (magnetic measurement), <span class="html-italic">J</span><sub>c</sub>, on magnetic field, μ<sub>o</sub><span class="html-italic">H</span>, for MgB<sub>2</sub>-based materials at 20 K (<b>a</b>) and 30 K (<b>b</b>) [<a href="#B108-materials-17-02787" class="html-bibr">108</a>]. 1 HP—high-pressure synthesized under 2 GPa at 1050 °C for 1 h from Mg(I):2B(I) with 10% SiC addition; 2 HP—high-pressure synthesized (2 GPa, 1050 °C, 1 h) from Mg(I):2B(I); 3 HP—high-pressure-sintered (2 GPa, 1050 °C, 1 h) from MgB<sub>2</sub> (VII); 4 HP—high-pressure-synthesized (2 GPa, 600 °C, 1 h) from Mg (II):2B (II); 5 SPS—spark-plasma-synthesized under 50 MPa at 600 °C for 0.3 h and then at 1050 °C for 0.5 h from Mg(I):2B(III); 6 HotP—synthesized by hot pressing (30 MPa, 900 °C, 1 h) from Mg(I):2B(III) with 10% Ta addition; 7 HIP—synthesized under high isostatic (gas) pressure (0.1 GPa, 900 °C, 1 h) from mixture of Mg(I):2B(III) with 10% Ti addition, which was precompacted into a ring shape by broaching; 8 PL—pressureless sintering (in flowing Ar under 0.1 MPa at 800 °C for 2 h) from mixture of Mg(I):2B(III) with 10% Ti addition, which was precompacted into a ring shape by broaching.</p> Full article ">Figure 2
<p>(<b>a</b>,<b>b</b>)—Sample structures obtained by SEM in COMPO (compositional) contrast: (<b>a</b>)—Sample sintered from MgB<sub>2</sub> (Type VI) under 2 GPa at 1000 °C for 1 h; bright small zones in (<b>a</b>) seem to be inclusions (containing O, Zr, Nb, and possibly ZrO<sub>2</sub>) appearing due to milling of initial MgB<sub>2</sub>. (<b>b</b>)—Structure of sample synthesized from Mg(I):2B(I) under 2 GPa at 800 °C. (<b>c</b>,<b>d</b>)—X-ray patterns of these samples, respectively [<a href="#B109-materials-17-02787" class="html-bibr">109</a>].</p> Full article ">Figure 3
<p>Critical current density, <span class="html-italic">J</span><sub>c,</sub> vs. magnetic field, μ<sub>o</sub><span class="html-italic">H</span>, of MgB<sub>2</sub> prepared (<b>a</b>) from Mg(I):2B(III) by SPS under 50 MPa at 600 °C for 0.3 h and then at 1050 °C for 0.5 h and (<b>b</b>) from Mg(I):2B(III) + 10 wt% Ti by HotP under 30 MPa at 1000 °C for 15 min [<a href="#B119-materials-17-02787" class="html-bibr">119</a>].</p> Full article ">Figure 4
<p>Structures of MgB<sub>2</sub> materials prepared from Mg(I):2B(III) mixtures under 50 MPa at 600 °C for 0.5 h and then at 1050 °C for 0.5 h. Images were obtained using SEM at different magnifications [<a href="#B109-materials-17-02787" class="html-bibr">109</a>]; (<b>a</b>–<b>c</b>)—SEI and, (<b>d</b>)—BEI.</p> Full article ">Figure 5
<p>Real (m’) part of the ac susceptibility (magnetic moment) vs. temperature, <span class="html-italic">T</span> [<a href="#B108-materials-17-02787" class="html-bibr">108</a>]. Small samples for the study were cut from superconductors prepared under 2 GPa. 1—edge of block 63 mm in diameter, prepared from Mg(I):2B (I and III) + 2 wt% Ti, at 800 °C; 2—center of the same block; 3—block 63 mm in diameter, Mg(I):2B(III) at 950 °C, 4—tablet 9 mm in diameter, Mg(I):2B(V) + 10 wt% Ti, at 1050 °C; 5—tablet 9 mm in diameter, Mg(I):2B(III) + 10 wt% Ti, at 800 °C; 6—tablet 9 mm in diameter, Mg(I):2B(III) + 10 wt% Ti at 1050 °C; 7—tablet 9 mm in diameter, Mg(I):2B(III) + 10 wt% Ta, at 1050 °C; 8—tablet 9 mm in diameter, Mg(II):2B(II) at 600 °C.</p> Full article ">Figure 6
<p>Thermal dependence of the upper critical magnetic field, <span class="html-italic">B</span><sub>c2</sub>, of bulk MgB<sub>2</sub> [<a href="#B120-materials-17-02787" class="html-bibr">120</a>,<a href="#B132-materials-17-02787" class="html-bibr">132</a>], prepared from: 1—Mg(II):2B(II) under 2 GPa (HP) at 600 °C for 1 h; 2—Mg(I):2B(III) (30 MPa (HotP), 800 °C, 2h); 3—Mg(I):2B(III) (50 MPa (SPS), at 600 °C for 0.3 h and then at 1050 °C for 0.5 h); 4—Mg(I):2B(III) (2 GPa (HP), 900 °C, 1 h); 5—Mg(I):2B(V) + 10 wt% Zr (2 GPa (HP), 800 °C, 1 h); 6—Mg(I):2B(V) + 10 wt% Ti (2 GPa (HP), 800 °C, 1 h); 7—Mg(I):2B(I) + 10 wt% SiC (2 GPa (HP), 1050 °C, 1 h).</p> Full article ">Figure 7
<p>(<b>a</b>–<b>d</b>)—Microstructures obtained by SEM at different magnifications of MgB<sub>2</sub> material prepared from Mg(II):2B(II) mixtures under 2 GPa at 600 °C for 1 h [<a href="#B109-materials-17-02787" class="html-bibr">109</a>]. (<b>a</b>)—SEI and, (<b>b</b>–<b>d</b>)—BEI.</p> Full article ">Figure 8
<p>The dependences of critical current density, <span class="html-italic">J</span><sub>c</sub>, at 20 K on a magnetic field. The MgB<sub>2</sub> samples were prepared from Mg(I):2B(I) and Mg(I):2B(III). The graph was composed using the data presented in [<a href="#B20-materials-17-02787" class="html-bibr">20</a>,<a href="#B98-materials-17-02787" class="html-bibr">98</a>,<a href="#B103-materials-17-02787" class="html-bibr">103</a>,<a href="#B119-materials-17-02787" class="html-bibr">119</a>].</p> Full article ">Figure 9
<p>(<b>a</b>,<b>b</b>)—SEM images in SEI mode of MgB<sub>2</sub> materials synthesized from Mg(I):2B(III) mixtures under 2 GPa, for 1 h at 800 and 1050 °C, respectively [<a href="#B109-materials-17-02787" class="html-bibr">109</a>]. (<b>c</b>,<b>d</b>)—Schema of MgB<sub>2</sub>-based material structures synthesized at low temperature of 800 °C (<b>e</b>) and high temperature of 1050 °C (<b>f</b>) [<a href="#B85-materials-17-02787" class="html-bibr">85</a>]. (<b>e</b>,<b>f</b>)—X-ray patterns of samples shown in (<b>a</b>,<b>b</b>) [<a href="#B113-materials-17-02787" class="html-bibr">113</a>].</p> Full article ">Figure 10
<p>Critical current density, <span class="html-italic">J</span><sub>c</sub>, vs. magnetic field, µ<sub>o</sub><span class="html-italic">H</span>, of MgB<sub>2</sub> materials prepared from Mg(I):2B(I) and Mg(I):2B(III) mixtures under 2 GPa, at 800 and 1050 °C for 1 h (<b>a</b>,<b>b</b>), respectively; additions of SiC (0.2–0.8 μm) to Mg(I):2B(I) mixture (<b>c</b>) and Ti (99%, 1–3 μm) to Mg(I):2B(III) (<b>d</b>) [<a href="#B103-materials-17-02787" class="html-bibr">103</a>].</p> Full article ">Figure 11
<p>(<b>a</b>) Maximal pinning forces, BFp(max), and corresponding values of magnetic fields at 20 K vs. synthesis pressure for MgB<sub>2</sub>-based materials synthesized from Mg(I) and B(III) at 800 (circles) and 1050 °C (stars); (<b>b</b>)—normalized pinning force, <span class="html-italic">F</span><sub>p</sub>, vs. magnetic field, <span class="html-italic">B</span>, calculated from the critical current density, <span class="html-italic">J</span><sub>c</sub>; and (<b>c</b>)—dependence of critical current density, <span class="html-italic">J</span><sub>c</sub>, on magnetic field. Designations: <span class="html-italic">k</span> = B<sub>peak</sub>/B<sub>n</sub>; PP—point pinning; GBP—grain boundary pinning; and MP—mixed pinning [<a href="#B128-materials-17-02787" class="html-bibr">128</a>]. Curves: (1) Mg(I):2B(I) + 10% SiC, 2GPa, 1050 °C, 1 h, k = 0.51 (PP); (2) Mg(I):2B(III) + 10% Ti, 2 GPa, 1050 °C, 1 h, k = 0.42 (MP); (3) Mg(I):2B(III), 50 MPa, 600 °C for 0.3 h and then 1050 °C for 0.5 h, k = 0.63 (&gt;PP?); (4) Mg(II):2B(II) with 3.5% C, 2 GPa, 600 °C, 1 h, k = 0.31 (GBP); (5) Mg(I):2B(III) + 10% Ti, 30 MPa for 1 h and then 1000 °C for 0.2 h, k = 0.42 (MP); (6) MgB<sub>2</sub>, 16 MPa, 1150 °C, 0.3 h, k = 0.45 (PP); (7) Mg(I):2B(III), in flowing Ar atmosphere under 0.1 MPa, 800 °C, 4 h, k = 0.35 (GBP).</p> Full article ">Figure 12
<p>(<b>a</b>)—X-ray patterns of the material synthesized under 2 GPa at 1200 °C for 1 h from Mg(I):12B(III); (<b>b</b>)—dependences of <span class="html-italic">J</span><sub>c</sub> on the external magnetic fields, μ<sub>o</sub><span class="html-italic">H</span>, at 20 K for the materials synthesized under 2 GPa for 1 h from Mg(I) and B(III), taken in the ratio Mg:xB, and synthesized at temperature, <span class="html-italic">T</span><sub>S</sub>: curves 1—Mg:12B, <span class="html-italic">T</span><sub>S</sub> = 1200 °C; curve 2—Mg:10B, <span class="html-italic">T</span><sub>S</sub> = 1200 °C; curve 3—Mg:8B, <span class="html-italic">T</span><sub>S</sub> = 1200 °C; curve 4—Mg:6B, <span class="html-italic">T</span><sub>S</sub> = 1200 °C; curve 5—Mg:4B, <span class="html-italic">T</span><sub>S</sub> = 1200 °C; curve 6—Mg:12B, <span class="html-italic">T</span><sub>S</sub> = 800 °C; curve 7—Mg:20B, <span class="html-italic">T</span><sub>S</sub> = 1200 °C; (<b>c</b>)—backscattering SEM image of the material prepared under 2 GPa at 1200 °C for 1 h from Mg(I):12B(III); (<b>d</b>) HRT—EM microstructure (of a MgB<sub>12</sub> grain, the stoichiometry of which was estimated by HRTEM EDX); (<b>e</b>)—dependences of critical current density, <span class="html-italic">J</span><sub>c</sub>, on magnetic fields, μ<sub>o</sub><span class="html-italic">H</span>, at 10–35 K for the materials prepared under 2 GPa at 1200 °C for 1 h from mixtures of Mg(I):8B(III) [<a href="#B103-materials-17-02787" class="html-bibr">103</a>].</p> Full article ">Figure 13
<p>Microstructures of the materials synthesized from Mg(I):B(III) with a 10 wt% of Ti (3–10 μm) addition under 2 GPa for 1 h at 800 (<b>a</b>,<b>c</b>) and 1050 °C (<b>b</b>,<b>d</b>) [<a href="#B108-materials-17-02787" class="html-bibr">108</a>]. X-ray patterns of these materials (<b>e</b>,<b>f</b>). (<b>c</b>,<b>d</b>) show the places where Ti is absent [<a href="#B103-materials-17-02787" class="html-bibr">103</a>,<a href="#B113-materials-17-02787" class="html-bibr">113</a>].</p> Full article ">Figure 14
<p>(<b>a</b>) Image of microstructure of MgB<sub>2</sub> sample with 10 wt% of Ti (3–10 μm); image 16a was taken in the place where the Ti grains are absent. (<b>b</b>–<b>d</b>)—EDX maps of boron, oxygen, and magnesium distributions over the area of the image shown in 16e (the brighter the area looks, the higher the amount of the element under study) [<a href="#B103-materials-17-02787" class="html-bibr">103</a>].</p> Full article ">Figure 15
<p>(<b>a</b>–<b>c</b>) SEM images of MgB<sub>2</sub> sample with 10 wt% of Ti powder (about 60 μm) synthesized under 2 GPa at 800 °C for 1 h: SEI (<b>a</b>–<b>c</b>) [<a href="#B113-materials-17-02787" class="html-bibr">113</a>]. Notations: “I”—Mg-B-O inclusions, MgB<sub>x</sub>—higher magnesium borides. In (<b>c</b>), the points marked by No. 1–6 are the points for which were made quantitative Auger analyses, the results of which are summarized in <a href="#materials-17-02787-t006" class="html-table">Table 6</a> [<a href="#B113-materials-17-02787" class="html-bibr">113</a>].</p> Full article ">Figure 16
<p>(<b>a</b>,<b>b</b>)—Microstructure of magnesium diboride synthesized from Mg(I):B(III) with 10 wt% TiH<sub>2</sub> addition under 2 GPa at 950 °C for 1 h in SEI [<a href="#B84-materials-17-02787" class="html-bibr">84</a>] (<b>a</b>) and COMPO (<b>b</b>) regimes.</p> Full article ">Figure 17
<p>Microstructure of materials with 10 wt% of SiC additions (0.2–0.8 μm) prepared from Mg(I):2B(I) under 2 GPa (HP) at 800 °C for 1 h (<b>a</b>–<b>d</b>) and at 1050 °C (<b>e</b>–<b>h</b>); (<b>a</b>,<b>c</b>,<b>e</b>,<b>g</b>)—SEI images; (<b>b</b>,<b>d</b>,<b>f</b>,<b>h</b>)—COMPO images; (<b>a</b>,<b>b</b>), (<b>c</b>,<b>d</b>), (<b>e</b>,<b>f</b>), and (<b>g</b>,<b>h</b>) are paired images of the same place under the same magnification but in different modes—SEI and COMPO [<a href="#B132-materials-17-02787" class="html-bibr">132</a>].</p> Full article ">Figure 18
<p>Characteristics of MgB<sub>2</sub>-based materials synthesized from Mg(I):2B(III) and Mg(II):2B(II) under 2 GPa for 1 h at different temperatures: (<b>a</b>–<b>f</b>)—dependences of critical current density, <span class="html-italic">J</span><sub>c</sub>, on magnetic field, <span class="html-italic">B</span>, of materials without (<b>a</b>) and with additions of titanium (Ti) (<b>b</b>,<b>e</b>), polyvalent titanium oxides (Ti-O) (<b>c</b>,<b>f</b>), and titanium carbide (TiC) (<b>d</b>); (<b>g</b>)—fields of irreversibility, <span class="html-italic">B</span><sub>irr</sub>, and (<b>h</b>) upper critical magnetic fields, <span class="html-italic">B</span><sub>C2</sub>, vs. temperature [<a href="#B85-materials-17-02787" class="html-bibr">85</a>].</p> Full article ">Figure 19
<p>(<b>a</b>)—X-ray diffraction pattern, (<b>b</b>)—dependence of critical current densities, <span class="html-italic">J</span><sub>c</sub>, on magnetic field, µ<sub>o</sub><span class="html-italic">H</span>, at 10, 20, 25, 30, 33, and 35 K of the material, prepared from Mg(I):2B(I) under 2 GPa at 1050 °C for 1 h [<a href="#B117-materials-17-02787" class="html-bibr">117</a>].</p> Full article ">Figure 20
<p>Calculated density of electronic states, <span class="html-italic">N</span>(<span class="html-italic">E</span>), for MgB<sub>2</sub> (<b>a</b>), MgB<sub>1.75</sub>O<sub>0.25</sub> (<b>b</b>), MgB<sub>1.5</sub>O<sub>0.5</sub> (<b>c</b>) per formula unit; (<b>d</b>)—calculated DOS at the Fermi level. <span class="html-italic">N</span>(<span class="html-italic">E</span><sub>F</sub>) depends on the oxygen concentration, x, in MgB<sub>2-x</sub>O<sub>x</sub> compounds (hollow squares). The total DOS and partial contributions of Mg, B, and O atoms are indicated by solid squares, solid triangles, and solid circles, respectively [<a href="#B132-materials-17-02787" class="html-bibr">132</a>].</p> Full article ">Figure 21
<p>(<b>a</b>)—Dependence of the binding energy, <span class="html-italic">E</span><sub>b</sub>, on the oxygen concentration, x, in MgB<sub>2-x</sub>O<sub>x</sub>/C<sub>x</sub>: 1, 3—homogeneous oxygen and carbon substitutions of boron atoms, respectively; 2, 4—the lowest binding energy vs. x for the ordered oxygen and carbon substitutions (for example, in nearby positions or in pairs), respectively. (<b>b</b>)—Z-contrast image of coherent oxygen-containing inclusions in [010] of MgB<sub>2</sub> obtained using HRTEM (high–resolution transmission microscopy). Bright atoms—Mg. The contrast increases in each second row and is due to the presence of oxygen in each second boron plane. The white arrows show the columns of atoms in which oxygen is present [<a href="#B117-materials-17-02787" class="html-bibr">117</a>].</p> Full article ">Figure 22
<p>Maps of electron density distribution for: (<b>a</b>)—MgB<sub>2</sub> (z = 1/2, (001)), (<b>b</b>)—MgB<sub>1.75</sub>O<sub>0.25</sub> (z = 1/4, (001) [<a href="#B108-materials-17-02787" class="html-bibr">108</a>]), (<b>c</b>)—MgB<sub>1.5</sub>O<sub>0.5</sub> (z = 1/4, (001)); z-coordinates of the plane of a 2 × 2 × 2 supercell, where z is given in units of the <span class="html-italic">c</span> parameter of a 2 × 2 × 2 MgB<sub>2</sub> supercell [<a href="#B132-materials-17-02787" class="html-bibr">132</a>]; (<b>d</b>)—MgB<sub>1.5</sub>O<sub>0.5</sub> in the transversal plane under an angle to the basal boron planes of the hexagonal unit cell to show the boron plane without imbedded oxygen atoms together with the Mg plane (the plane goes through the 7-B, 8-B, and 1′-B, 2′-B positions of a 2 × 2 × 2 supercell [<a href="#B132-materials-17-02787" class="html-bibr">132</a>]); (<b>e</b>)—MgB<sub>1.5</sub>C<sub>0.5</sub> (z = 1/4, (001)); (<b>f</b>)—MgB<sub>1.5</sub>C<sub>0.5</sub> in the transversal plane under an angle to the basal boron planes (the plane goes through the 7-B, 8-B, and 1′-B, 2′-B positions of a 2 × 2 × 2 supercell) [<a href="#B117-materials-17-02787" class="html-bibr">117</a>].</p> Full article ">Figure 23
<p>Examples of MgB2 bulk superconductors: (<b>a</b>)—obtained using HotP, (<b>b</b>) [<a href="#B120-materials-17-02787" class="html-bibr">120</a>], (<b>c</b>) —obtained using HP and then the rings were cut mechanically, and (<b>d</b>)—obtained by machining a bulk cylinder manufactured using SPS [<a href="#B26-materials-17-02787" class="html-bibr">26</a>].</p> Full article ">Figure 24
<p>High quasi-hydrostatic pressing (HP) in ISM NASU. Hydraulic 140 MN-effort press from the ASEA company (<b>a</b>), hydraulic 25 MN-effort press (<b>b</b>), cylinder piston high–pressure apparatus (HPA) (<b>c</b>), recessed-anvil type (HPA) for 25 MN press (<b>d</b>), and scheme of high–pressure cell of the recessed-anvil HPA (before and after loading) (<b>e</b>).</p> Full article ">Figure 25
<p>Hydraulic press DO 630 for hot pressing with generator and inductor (<b>a</b>,<b>b</b>); general view of inductor of hot press during heating (shining window—opening for temperature estimation by pyrometer) (<b>c</b>), scheme of assembled inductor (<b>d</b>).</p> Full article ">Figure 26
<p>Installation for spark plasma sintering (<b>a</b>) and, scheme of SPS heating chamber (<b>b</b>) [<a href="#B166-materials-17-02787" class="html-bibr">166</a>].</p> Full article ">Figure 27
<p>(<b>a</b>)—The schemes of an SFCL model and a testing circuit for the simulation of a fault event. (<b>b</b>)—Typical oscilloscope traces of the current in a protected circuit (black, solid curve) and the voltage drop across the primary coil of the SFCL model (red, dashed curve) at 50 Hz and about 4 K (from [<a href="#B90-materials-17-02787" class="html-bibr">90</a>]). The experiment details are described in [<a href="#B120-materials-17-02787" class="html-bibr">120</a>]. “A”—is ammeter.</p> Full article ">Figure 28
<p>General view of azebra-type rotor of a 1300W/215V superconducting motor with MgB<sub>2</sub> bulk superconductor [<a href="#B9-materials-17-02787" class="html-bibr">9</a>].</p> Full article ">Figure 29
<p>(<b>a</b>) Magnetic shield of MgB<sub>2</sub> in the shape of a cup (outer radius, <span class="html-italic">R</span><sub>o</sub> = 10.15 mm; inner radius, <span class="html-italic">R</span><sub>i</sub> =7.0 mm; external height, <span class="html-italic">h</span><sub>e</sub> = 22.5 mm; internal depth, <span class="html-italic">d</span><sub>i</sub> = 18.3 mm). The material is machinable by chipping. The shielding factors (i.e., the ratio between an outer applied magnetic field, <span class="html-italic">H</span><sub>appl</sub>, and an inner magnetic field measured by a Hall sensor at different z<sub>1</sub>–z<sub>5</sub> positions (<b>b</b>)) at <span class="html-italic">T</span> = 30 K are shown in (<b>c</b>). The dashed lines represent the shielding factors computed in correspondence with the Hall probe positions, assuming the magnetic field dependence of <span class="html-italic">J</span><sub>c</sub>(<span class="html-italic">B</span>) at 30 K. (<a href="#materials-17-02787-f002" class="html-fig">Figure 2</a> in [<a href="#B26-materials-17-02787" class="html-bibr">26</a>] adapts the results obtained in [<a href="#B159-materials-17-02787" class="html-bibr">159</a>]).</p> Full article ">
12 pages, 8625 KiB  
Article
Analysis of the Steelmaking Process via Data Mining and Pearson Correlation
by Susana Carrasco-López, Martín Herrera-Trejo, Manuel Castro-Román, Fabián Castro-Uresti and Edgar Iván Castro-Cedeño
Materials 2024, 17(11), 2786; https://doi.org/10.3390/ma17112786 - 6 Jun 2024
Cited by 1 | Viewed by 927
Abstract
The continuous improvement of the steelmaking process is a critical issue for steelmakers. In the production of Ca-treated Al-killed steel, the Ca and S contents are controlled for successful inclusion modification treatment. In this study, a machine learning technique was used to build [...] Read more.
The continuous improvement of the steelmaking process is a critical issue for steelmakers. In the production of Ca-treated Al-killed steel, the Ca and S contents are controlled for successful inclusion modification treatment. In this study, a machine learning technique was used to build a decision tree classifier and thus identify the process variables that most influence the desired Ca and S contents at the end of ladle furnace refining. The attribute of the root node of the decision tree was correlated with process variables via the Pearson formalism. Thus, the attribute of the root node corresponded to the sulfur distribution coefficient at the end of the refining process, and its value allowed for the discrimination of satisfactory heats from unsatisfactory heats. The variables with higher correlation with the sulfur distribution coefficient were the content of sulfur in both steel and slag at the end of the refining process, as well as the Si content at that stage of the process. As secondary variables, the Si content and the basicity of the slag at the end of the refining process were correlated with the S content in the steel and slag, respectively, at that stage. The analysis showed that the conditions of steel and slag at the beginning of the refining process and the efficient S removal during the refining process are crucial for reaching desired Ca and S contents. Full article
(This article belongs to the Special Issue Metallurgical Process Simulation and Optimization—2nd Volume)
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<p>Processing route of Ca-treated Al-killed steel.</p> Full article ">Figure 2
<p>Decision tree classifier.</p> Full article ">Figure 3
<p>Variation in the experimental sulfur distribution coefficient, Ls<sub>(exp)</sub>, with the S content in the steel, %<span class="underline">S</span>.</p> Full article ">Figure 4
<p>“Heatmap” for the estimated Pearson correlation.</p> Full article ">Figure 5
<p>Correlation of the sulfur content in the slag (%S) with the sulfur content in the steel (<span class="underline">S</span>).</p> Full article ">Figure 6
<p>Variation in Ls<sub>(exp)</sub> with the Si content in the steel (%<span class="underline">Si</span>).</p> Full article ">Figure 7
<p>Variation in the S content in steel, %<span class="underline">S</span>, with the <span class="underline">Si</span> content in the steel, %<span class="underline">Si</span>.</p> Full article ">Figure 8
<p>Variation in Ls<sub>(exp)</sub> with respect to slag oxidation level (%FeO + %MnO).</p> Full article ">Figure 9
<p>Chemical composition of slags in the Al<sub>2</sub>O<sub>3</sub>-CaO-SiO<sub>2</sub>-10%MgO diagram at 1873 K.</p> Full article ">Figure 10
<p>Variation in the sulfur content in the slag (%S) with the basicity of the slag.</p> Full article ">Figure 11
<p>Variation in Ls<sub>(exp)</sub> with respect to the sulfur capacity of slag Cs.</p> Full article ">Figure 12
<p>Variation in the experimental sulfur distribution coefficient, Ls<sub>(exp)</sub>, with the S content in the steel %<span class="underline">S</span> for the second steel.</p> Full article ">
17 pages, 16946 KiB  
Article
Influence of Heat Treatment Condition on the Microstructure, Microhardness and Corrosion Resistance of Ag-Sn-In-Ni-Te Alloy Wire
by Ling Shao, Shunle Zhang, Liepeng Hu, Yincheng Wu, Yingqi Huang, Ping Le, Sheng Dai, Weiwei Li, Na Xue, Feilong Xu and Liu Zhu
Materials 2024, 17(11), 2785; https://doi.org/10.3390/ma17112785 - 6 Jun 2024
Cited by 23 | Viewed by 1062
Abstract
Ag-Sn-In-Ni-Te alloy ingots were produced through a heating–cooling combined mold continuous casting technique; they were then drawn into wires. However, during the drawing process, the alloy wires tended to harden, making further diameter reduction challenging. To overcome this, heat treatment was necessary to [...] Read more.
Ag-Sn-In-Ni-Te alloy ingots were produced through a heating–cooling combined mold continuous casting technique; they were then drawn into wires. However, during the drawing process, the alloy wires tended to harden, making further diameter reduction challenging. To overcome this, heat treatment was necessary to soften the previously drawn wires. The study investigated how variations in heat treatment temperature and holding time affected the microstructure, microhardness and corrosion resistance of the alloy wires. The results indicate that the alloy wires subjected to heat treatment at 700 °C for 2 h not only exhibited a uniform microstructure distribution, but also demonstrated low microhardness and excellent corrosion resistance. Full article
(This article belongs to the Special Issue Microstructure Engineering of Metals and Alloys, Volume II)
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<p>Schematic diagram of Ag-Sn-In-Ni-Te alloy wire preparation process.</p> Full article ">Figure 2
<p>XRD patterns for the samples before and after heat treatment: (<b>a</b>) sample untreated; (<b>b</b>) samples 700—2 h, 750—2 h and 800—2 h; (<b>c</b>) samples 800—5 h and 850—5 h.</p> Full article ">Figure 3
<p>Optical microstructure of Ag-Sn-In-Ni-Te alloy samples before and after heat treatment: (<b>a1</b>) longitudinal section of sample untreated, (<b>a2</b>) longitudinal section of sample 700—2 h, (<b>a3</b>) longitudinal section of sample 750—2 h, (<b>b1</b>) longitudinal section of sample 800—2 h, (<b>b2</b>) longitudinal section of sample 800—5 h, (<b>b3</b>) longitudinal section of sample 850—5 h, (<b>c1</b>) cross-section of sample untreated, (<b>c2</b>) cross-section of sample 700—2 h, (<b>c3</b>) cross-section of sample 750—2 h, (<b>d1</b>) cross-section of sample 800—2 h, (<b>d2</b>) cross-section of sample 800—5 h, (<b>d3</b>) cross-section of sample 850—5 h.</p> Full article ">Figure 4
<p>Element mapping results for the longitudinal section and cross-section of sample untreated. Group (<b>a</b>) images are SEM micrographs and EDS spectra showing the distribution of Ag, Sn, In, Te and Ni elements in the longitudinal section; group (<b>b</b>) images are SEM micrographs and EDS spectra showing the distribution of Ag, Sn, In, Te and Ni elements in the cross-section.</p> Full article ">Figure 5
<p>SEM microstructure of Ag-Sn-In-Ni-Te alloy samples after different heat treatments: cross-section of sample 700—2 h (<b>a</b>,<b>b</b>), cross-section of sample 750—2 h (<b>c</b>,<b>d</b>) and cross-section of sample 800—2 h (<b>e</b>,<b>f</b>).</p> Full article ">Figure 6
<p>Element mapping results for two distinct size particles distributed across matrix of sample 700—2 h. SEM micrographs (<b>a1</b>,<b>c1</b>); the distribution of Ag (<b>a2</b>,<b>c2</b>), Sn (<b>a3</b>,<b>c3</b>), In (<b>b1</b>,<b>d1</b>), Te (<b>b2</b>,<b>d2</b>) and Ni (<b>b3</b>,<b>d3</b>) elements.</p> Full article ">Figure 7
<p>Spectra results of matrix and two distinct size particles distributed across matrix of sample 700—2 h. Matrix (<b>a</b>); Ag<sub>2</sub>Te (<b>b</b>), NiSn<sub>2</sub> (<b>c</b>).</p> Full article ">Figure 8
<p>SEM microstructure of Ag-Sn-In-Ni-Te alloy samples after different heat treatments: cross-section of sample 800—5 h (<b>a</b>–<b>d</b>); cross-section of sample 850—5 h (<b>e</b>–<b>h</b>).</p> Full article ">Figure 9
<p>Element mapping results for different phases distributed across a matrix of sample 850—5 h. SEM micrographs (<b>a1</b>,<b>c1</b>); the distribution of Ag (<b>a2</b>,<b>c2</b>), Sn (<b>a3</b>,<b>c3</b>), In (<b>b1</b>,<b>d1</b>), Te (<b>b2</b>,<b>d2</b>) and Ni (<b>b3</b>,<b>d3</b>) elements.</p> Full article ">Figure 10
<p>Microhardness of Ag-Sn-In-Ni-Te alloy samples before and after heat treatment.</p> Full article ">Figure 11
<p>Potentiondynamic polarization curves of the prepared samples in 3.5% NaCl solution at room temperature.</p> Full article ">Figure 12
<p>Electrochemical impedance spectroscopy of the prepared samples in 3.5% NaCl solution at room temperature (<b>a</b>) and R(CR) equivalent circuit model (<b>b</b>).</p> Full article ">
17 pages, 3580 KiB  
Article
Impact of Temperature Optimization of ITO Thin Film on Tandem Solar Cell Efficiency
by Elif Damgaci, Emre Kartal, Furkan Gucluer, Ayse Seyhan and Yuksel Kaplan
Materials 2024, 17(11), 2784; https://doi.org/10.3390/ma17112784 - 6 Jun 2024
Viewed by 1766
Abstract
This study examined the impact of temperature optimization on indium tin oxide (ITO) films in monolithic HJT/perovskite tandem solar cells. ITO films were deposited using magnetron sputtering at temperatures ranging from room temperature (25 °C) to 250 °C. The sputtering target was ITO, [...] Read more.
This study examined the impact of temperature optimization on indium tin oxide (ITO) films in monolithic HJT/perovskite tandem solar cells. ITO films were deposited using magnetron sputtering at temperatures ranging from room temperature (25 °C) to 250 °C. The sputtering target was ITO, with a mass ratio of In2O3 to SnO2 of 90% to 10%. The effects of temperature on the ITO film were analyzed using X-ray diffraction (XRD), spectroscopic ellipsometry, and sheet resistance measurements. Results showed that all ITO films exhibited a polycrystalline morphology, with diffraction peaks corresponding to planes (211), (222), (400), (440), and (622), indicating a cubic bixbyite crystal structure. The light transmittance exceeded 80%, and the sheet resistance was 75.1 Ω/sq for ITO deposited at 200 °C. The optical bandgap of deposited ITO films ranged between 3.90 eV and 3.93 eV. Structural and morphological characterization of the perovskite solar cell was performed using XRD and FE-SEM. Tandem solar cell performance was evaluated by analyzing current density-voltage characteristics under simulated sunlight. By optimizing the ITO deposition temperature, the tandem cell achieved a power conversion efficiency (PCE) of 16.74%, resulting in enhanced tandem cell efficiency. Full article
(This article belongs to the Topic Optical and Optoelectronic Properties of Materials and Their Applications)
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<p>HJT solar cell (2.5 × 2.5 cm<sup>2</sup>) (<b>a</b>), HJT/perovskite tandem solar cell (active area: 1.45 cm<sup>2</sup>) (<b>b</b>), thin film colors and deposition methods (<b>c</b>), HJT/perovskite tandem solar cell eV diagram (<b>d</b>).</p> Full article ">Figure 2
<p>XRD patterns of ITO-RT, ITO-150, ITO-175, ITO-200, and ITO-250 films samples.</p> Full article ">Figure 3
<p>Texture coefficients (TC) of ITO films produced at different temperatures calculated from XRD patterns.</p> Full article ">Figure 4
<p>Optical transmittance spectra versus wavelength for ITO deposited on glass substrates via the PVD system at ITO-RT, ITO-150, ITO-175, ITO-200, and ITO-250 different temperatures.</p> Full article ">Figure 5
<p>Optical reflectance spectra of ITO films deposited on glass substrates via the PVD system at ITO-RT, ITO-150, ITO-175, ITO-200, and ITO-250 temperatures, plotted against wavelength.</p> Full article ">Figure 6
<p>Band gap measurement of ITO deposited at different temperatures, obtained by plotting <span class="html-italic">h</span><span class="html-italic">ν</span> versus (αhν)<sup>2</sup>. The optical band gap of the deposited ITO films was calculated to be between 3.90 eV and 3.93 eV (The band gap was calculated using fitted curves, which are represented by dashed lines in the figure).</p> Full article ">Figure 7
<p>Sheet resistance, FOM, and resistivity graph of ITO films as a function of the temperature. The FOM values calculated from Haacke’s method [<a href="#B49-materials-17-02784" class="html-bibr">49</a>], which optimally characterized the optical and electrical properties of ITO films through electrical sheet resistance and optical transmittance.</p> Full article ">Figure 8
<p>Current density (J)-voltage (V) graphs of HJT solar cells with ITO layers deposited at different temperatures: ITO-RT, ITO-150, ITO-175, ITO-200, and ITO-250.</p> Full article ">Figure 9
<p>The XRD results for the monolithic c-Si heterojunction perovskite tandem solar cell, including a focus on the top cell.</p> Full article ">Figure 10
<p>c-Si HJT/perovskite tandem solar cell SEM images. (<b>a</b>) Random pyramid-structured n-type c-Si and area with perovskite solar cell, (<b>b</b>) cross-section view of tandem layers and thickness (the yellow circles), (<b>c</b>) the cross-section of HJT solar cell, (<b>d</b>) top perovskite cell structure.</p> Full article ">Figure 11
<p>A comparison of the efficiency of a monolithic tandem solar cell comprising n-type c-Si/ITO/SnO<sub>2</sub>/CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub>−xClx/Spiro-OMeTAD/ITO/Ag and a c-Si HJT solar cell is presented. The tandem solar cell’s conversion efficiencies utilizing ITO deposited at room temperature and 200 °C are designated as Tandem-RT (15.78%) and Tandem-200 (16.74%), respectively.</p> Full article ">
18 pages, 4568 KiB  
Article
Ecologically Modified Leather of Bacterial Origin
by Dawid Lisowski, Stanisław Bielecki, Stefan Cichosz and Anna Masek
Materials 2024, 17(11), 2783; https://doi.org/10.3390/ma17112783 - 6 Jun 2024
Cited by 1 | Viewed by 1020
Abstract
The research presented here is an attempt to develop an innovative and environmentally friendly material based on bacterial nanocellulose (BNC), which will be able to replace both animal skins and synthetic polymer products. Bacterial nanocellulose becomes stiff and brittle when dried, so attempts [...] Read more.
The research presented here is an attempt to develop an innovative and environmentally friendly material based on bacterial nanocellulose (BNC), which will be able to replace both animal skins and synthetic polymer products. Bacterial nanocellulose becomes stiff and brittle when dried, so attempts have been made to plasticise this material so that BNC can be used in industry. The research presented here focuses on the ecological modification of bacterial nanocellulose with vegetable oils such as rapeseed oil, linseed oil, and grape seed oil. The effect of compatibilisers of a natural origin on the plasticisation process of BNC, such as chlorophyll, curcumin, and L-glutamine, was also evaluated. BNC samples were modified with rapeseed, linseed, and grapeseed oils, as well as mixtures of each of these oils with the previously mentioned additives. The modification was carried out by passing the oil, or oil mixture, through the BNC using vacuum filtration, where the BNC acted as a filter. The following tests were performed to determine the effect of the modification on the BNC: FTIR spectroscopic analysis, contact angle measurements, and static mechanical analysis. As a result of the modification, the BNC was plasticised. Rapeseed oil proved to be the best for this purpose, with the help of which a material with good strength and elasticity was obtained. Full article
(This article belongs to the Special Issue New Advances in Elastomer Materials and Its Composites)
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<p>FTIR spectra of samples: (<b>a</b>) modified with rapeseed oil without additives (BNC/R), modified with rapeseed and toluene (BNC/R/Tol); (<b>b</b>) modified with rapeseed oil with added L-glutamine (BNC/R/Gln), modified with rapeseed oil with added L-glutamine and toluene (BNC/R/Tol/Gln); (<b>c</b>) modified with rapeseed oil with added chlorophyll (BNC/R/Chl), modified with rapeseed oil with added chlorophyll and toluene (BNC/R/Tol/Chl); (<b>d</b>) modified with rapeseed oil with added curcumin (BNC/R/Cur), modified with rapeseed oil with added curcumin and toluene (BNC/R/Tol/Cur); (<b>e</b>) unmodified bacterial cellulose; (<b>f</b>) carbonyl indexes of samples.</p> Full article ">Figure 2
<p>FTIR spectra of samples: (<b>a</b>) modified with linseed oil without additives (BNC/L), modified with linseed and toluene (BNC/L/Tol); (<b>b</b>) modified with linseed oil with added L-glutamine (BNC/L/Gln), modified with linseed oil with added L-glutamine and toluene (BNC/L/Tol/Gln); (<b>c</b>) modified with linseed oil with added chlorophyll (BNC/L/Chl), modified with linseed oil with added chlorophyll and toluene (BNC/L/Tol/Chl); (<b>d</b>) modified with linseed oil with added curcumin (BNC/L/Cur), modified with linseed oil with added curcumin and toluene (BNC/L/Tol/Cur); (<b>e</b>) unmodified bacterial cellulose; (<b>f</b>) carbonyl indexes of samples.</p> Full article ">Figure 3
<p>FTIR spectra of samples: (<b>a</b>) modified with grapeseed oil without additives (BNC/G), modified with grapeseed and toluene (BNC/G/Tol); (<b>b</b>) modified with grapeseed oil with added L-glutamine (BNC/G/Gln), modified with grapeseed oil with added L-glutamine and toluene (BNC/G/Tol/Gln); (<b>c</b>) modified with grapeseed oil with added chlorophyll (BNC/G/Chl), modified with grapeseed oil with added chlorophyll and toluene (BNC/G/Tol/Chl); (<b>d</b>) modified with grapeseed oil with added curcumin (BNC/G/Cur), modified with grapeseed oil with added curcumin and toluene (BNC/G/Tol/Cur); (<b>e</b>) unmodified bacterial cellulose; (<b>f</b>) carbonyl indexes of samples.</p> Full article ">Figure 4
<p>Contact angles of the samples: (<b>a</b>) modified with rapeseed oil without additives (BNC/R); (<b>b</b>) modified with rapeseed oil with toluene (BNC/R/Tol); (<b>c</b>) modified with rapeseed oil with added chlorophyll (BNC/R/Chl); (<b>d</b>) modified with rapeseed oil with added chlorophyll and toluene (BNC/R/Tol/Chl); (<b>e</b>) modified with rapeseed oil with added curcumin (BNC/R/Cur); (<b>f</b>) modified with rapeseed oil with added curcumin and toluene (BNC/R/Tol/Cur); (<b>g</b>) unmodified bacterial cellulose (BNC); (<b>h</b>) a compilation of the mean values of the contact angles for the samples listed.</p> Full article ">Figure 5
<p>Contact angles of the samples: (<b>a</b>) modified with linseed oil without additives (BNC/L); (<b>b</b>) modified with linseed oil with toluene (BNC/L/Tol); (<b>c</b>) modified with linseed oil with added chlorophyll (BNC/L/Chl); (<b>d</b>) modified with linseed oil with added chlorophyll and toluene (BNC/L/Tol/Chl); (<b>e</b>) modified with linseed oil with added curcumin (BNC/L/Cur); (<b>f</b>) modified with linseed oil with added curcumin and toluene (BNC/L/Tol/Cur); (<b>g</b>) unmodified bacterial cellulose (BNC); (<b>h</b>) a compilation of the mean values of the contact angles for the samples listed.</p> Full article ">Figure 6
<p>Contact angles of the samples: (<b>a</b>) modified with grapeseed oil without additives (BNC/G); (<b>b</b>) modified with grapeseed oil with toluene (BNC/G/Tol); (<b>c</b>) modified with grapeseed oil with added chlorophyll (BNC/G/Chl); (<b>d</b>) modified with grapeseed oil with added chlorophyll and toluene (BNC/G/Tol/Chl); (<b>e</b>) modified with grapeseed oil with added curcumin (BNC/G/Cur); (<b>f</b>) modified with grapeseed oil with added curcumin and toluene (BNC/G/Tol/Cur); (<b>g</b>) unmodified bacterial cellulose (BNC); (<b>h</b>) a compilation of the mean values of the contact angles for the samples listed.</p> Full article ">Figure 7
<p>Tensile strength and elongation at break of samples: unmodified bacterial cellulose (BNC); modified with rapeseed oil without additives (BNC/R); modified with rapeseed and toluene (BNC/R/Tol); modified with rapeseed oil with added L-glutamine (BNC/R/Gln); modified with rapeseed oil with added L-glutamine and toluene (BNC/R/Tol/Gln); modified with rapeseed oil with added chlorophyll (BNC/R/Chl); modified with rapeseed oil with added chlorophyll and toluene (BNC/R/Tol/Chl); modified with rapeseed oil with added curcumin (BNC/R/Cur); modified with rapeseed oil with added curcumin and toluene (BNC/R/Tol/Cur).</p> Full article ">Figure 8
<p>Tensile strength and elongation at break of samples: unmodified bacterial cellulose (BNC); modified with linseed oil without additives (BNC/L); modified with linseed and toluene (BNC/L/Tol); modified with linseed oil with added L-glutamine (BNC/L/Gln); modified with linseed oil with added L-glutamine and toluene (BNC/L/Tol/Gln); modified with linseed oil with added chlorophyll (BNC/L/Chl); modified with linseed oil with added chlorophyll and toluene (BNC/L/Tol/Chl); modified with linseed oil with added curcumin (BNC/L/Cur); modified with linseed oil with added curcumin and toluene (BNC/L/Tol/Cur).</p> Full article ">Figure 9
<p>Tensile strength of samples: unmodified bacterial cellulose (BNC); modified with grapeseed oil without additives (BNC/G); modified with grapeseed and toluene (BNC/G/Tol); modified with grapeseed oil with added L-glutamine (BNC/G/Gln); modified with grapeseed oil with added L-glutamine and toluene (BNC/G/Tol/Gln); modified with grapeseed oil with added chlorophyll (BNC/G/Chl); modified with grapeseed oil with added chlorophyll and toluene (BNC/G/Tol/Chl); modified with grapeseed oil with added curcumin (BNC/G/Cur); modified with grapeseed oil with added curcumin and toluene (BNC/G/Tol/Cur).</p> Full article ">Figure 10
<p>Diagram showing a simplified plasticisation mechanism.</p> Full article ">
20 pages, 4859 KiB  
Article
Axial Compressive Behaviours of Coal Gangue Concrete-Filled Circular Steel Tubular Stub Columns after Chloride Salt Corrosion
by Tong Zhang, Hongshan Wang, Xuanhe Zheng and Shan Gao
Materials 2024, 17(11), 2782; https://doi.org/10.3390/ma17112782 - 6 Jun 2024
Viewed by 972
Abstract
The axial compressive behaviours of coal gangue concrete-filled steel tube (GCFST) columns after chloride salt corrosion were investigated numerically. Numerical modelling was conducted through the static analysis method by finite element (FE) analysis. The failure mechanism, residual strength, and axial load–displacement curves were [...] Read more.
The axial compressive behaviours of coal gangue concrete-filled steel tube (GCFST) columns after chloride salt corrosion were investigated numerically. Numerical modelling was conducted through the static analysis method by finite element (FE) analysis. The failure mechanism, residual strength, and axial load–displacement curves were validated against tests of the coal gangue aggregate concrete-filled steel tube (GCFST) columns at room and natural aggregate concrete-filled steel tube (NCFST) columns after salt corrosion circumstance. According to the analysis on the stress distribution of the steel tube, the stress value of the steel tube decreased as the corrosion rate increased at the same characteristic point. A parametric analysis was carried out to determine the effect of crucial variation on residual strength. It indicated that material strength, the steel ratio, and the corrosion rate made a profound impact on the residual strength from the FE. The residual strength of the columns exposed to chloride salt was in negative correlation with the corrosion rate. The impact on the residual strength of the column was little, obvious by the replacement rate of the coal gangue. A simplified design formula for predicting the ultimate strength of GCFST columns after chloride salt corrosion exposure was proposed. Full article
(This article belongs to the Topic Ideas for Future Cities: Intelligent, Low-Carbon and Healthy)
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<p>Stress-strain curve of Q345 steel after corrosion exposure.</p> Full article ">Figure 2
<p>The established model of the C-GCFST stub column with uniform corrosion damage.</p> Full article ">Figure 3
<p>The numerical and experimental failure pattern of the typical C-CFST stub columns. (<b>a</b>) C3.0-0-20; (<b>b</b>) C4.5-0-20; (<b>c</b>) Q235-20-0; (<b>d</b>) Q345-20-0; (<b>e</b>) SCGA-100-2.75; (<b>f</b>) SCGA-100-3.5; (<b>g</b>) SCGA-100-4.5; (<b>h</b>) S40-50-c; (<b>i</b>) S40-100-c.</p> Full article ">Figure 4
<p>The compared numerical and experimental N-∆ curves of the C-CFST stub after chloride salt corrosion. (<b>a</b>) C3.0-0-10 and C4.5-0-10; (<b>b</b>) C3.0-0-20 and C4.5-0-20; (<b>c</b>) C3.0-0-30 and C4.5-0-30; (<b>d</b>) Q235-5-0 and Q345-5-0; (<b>e</b>) Q235-10-0 and Q345-10-0; (<b>f</b>) Q235-20-0 and Q345-20-0.</p> Full article ">Figure 5
<p>The compared numerical and experimental <span class="html-italic">N–∆</span> curves of the C-GCFST stub at room temperature. (<b>a</b>) SCGA-50-2.75 and SCGA-50-3.75; (<b>b</b>) SCGA-100-2.75 and SCGA-100-3.75; (<b>c</b>) SCGA-50-4.5 and SCGA-100-4.5; (<b>d</b>) S40-50-a and S60-50-a; (<b>e</b>) S40-50-b and S60-50-b; (<b>f</b>) S40-50-c and S60-50-c; (<b>g</b>) S40-100-a and S60-100-a; (<b>h</b>) S40-100-b and S60-100-b; (<b>i</b>) S40-100-c and S60-100-c.</p> Full article ">Figure 5 Cont.
<p>The compared numerical and experimental <span class="html-italic">N–∆</span> curves of the C-GCFST stub at room temperature. (<b>a</b>) SCGA-50-2.75 and SCGA-50-3.75; (<b>b</b>) SCGA-100-2.75 and SCGA-100-3.75; (<b>c</b>) SCGA-50-4.5 and SCGA-100-4.5; (<b>d</b>) S40-50-a and S60-50-a; (<b>e</b>) S40-50-b and S60-50-b; (<b>f</b>) S40-50-c and S60-50-c; (<b>g</b>) S40-100-a and S60-100-a; (<b>h</b>) S40-100-b and S60-100-b; (<b>i</b>) S40-100-c and S60-100-c.</p> Full article ">Figure 6
<p>Load–displacement curves.</p> Full article ">Figure 7
<p>Mises stress distribution of the steel tube at point A. (<b>a</b>) <span class="html-italic">ρ</span> = 0; (<b>b</b>) <span class="html-italic">ρ</span> = 10%; (<b>c</b>) <span class="html-italic">ρ</span> = 30% (unit: Pa).</p> Full article ">Figure 8
<p>Mises stress distribution of the steel tube at point B. (<b>a</b>) <span class="html-italic">ρ</span> = 0; (<b>b</b>) <span class="html-italic">ρ</span> = 10%; (<b>c</b>) <span class="html-italic">ρ</span> = 30% (unit: Pa).</p> Full article ">Figure 9
<p>Mises stress distribution of the steel tube at point C. (<b>a</b>) <span class="html-italic">ρ</span> = 0; (<b>b</b>) <span class="html-italic">ρ</span> = 10%; (<b>c</b>) <span class="html-italic">ρ</span> = 30% (unit: Pa).</p> Full article ">Figure 10
<p>Mises stress distribution of the steel tube at point D. (<b>a</b>) <span class="html-italic">ρ</span> = 0; (<b>b</b>) <span class="html-italic">ρ</span> = 10%; (<b>c</b>) <span class="html-italic">ρ</span> = 30% (unit: Pa).</p> Full article ">Figure 11
<p>The influence of variations on Nu: (<b>a</b>) replacement rate; (<b>b</b>) the yield strength of the steel tube; (<b>c</b>) concrete strength; and (<b>d</b>) steel ratio.</p> Full article ">Figure 12
<p>The curve of <span class="html-italic">N</span><sub>d</sub>/<span class="html-italic">N</span><sub>0</sub> and <span class="html-italic">r</span>.</p> Full article ">Figure 13
<p>Results of <span class="html-italic">Nd</span> and <span class="html-italic">Nf</span>.</p> Full article ">
2 pages, 527 KiB  
Correction
Correction: Chaparro et al. Whey as an Alternative Nutrient Medium for Growth of Sporosarcina pasteurii and Its Effect on CaCO3 Polymorphism and Fly Ash Bioconsolidation. Materials 2021, 14, 2470
by Sandra Chaparro, Hugo A. Rojas, Gerardo Caicedo, Gustavo Romanelli, Antonio Pineda, Rafael Luque and José J. Martínez
Materials 2024, 17(11), 2781; https://doi.org/10.3390/ma17112781 - 6 Jun 2024
Viewed by 629
Abstract
The Editorial Office was made aware of an error in Figure S1 within the original publication [...] Full article
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<p>IR Spectra of CaCO<sub>3</sub> produced with different whey treatments. (<b>a</b>) IR spectra fingerprint showing the characteristic bands of vaterite (V) and calcite (C) (<b>b</b>) IR spectra in the region of 2000–600 cm<sup>−1</sup> where the presence of protein residues can be evidenced by the amide bands; C=O stretching mode of the amide functional group (1600–1700 cm<sup>−1</sup>), and N–H bending and C–N stretching vibrations (1500–1600 cm<sup>−1</sup>).</p> Full article ">
9 pages, 1253 KiB  
Article
TaF4: A Novel Two-Dimensional Antiferromagnetic Material with a High Néel Temperature Investigated Using First-Principles Calculations
by Jia Luo, Qingkai Zhang, Jindong Lin, Yuxiang Ni, Hongyan Wang, Yongliang Tang and Mu Lan
Materials 2024, 17(11), 2780; https://doi.org/10.3390/ma17112780 - 6 Jun 2024
Viewed by 1320
Abstract
The structural, electronic, and magnetic properties of a novel two-dimensional monolayer material, TaF4, are investigated using first-principles calculations. The dynamical and thermal stabilities of two-dimensional monolayer TaF4 were confirmed using its phonon dispersion spectrum and molecular dynamics calculations. The band [...] Read more.
The structural, electronic, and magnetic properties of a novel two-dimensional monolayer material, TaF4, are investigated using first-principles calculations. The dynamical and thermal stabilities of two-dimensional monolayer TaF4 were confirmed using its phonon dispersion spectrum and molecular dynamics calculations. The band structure obtained via the high-accuracy HSE06 (Heyd–Scuseria–Ernzerhof 2006) functional theory revealed that monolayer two-dimensional TaF4 is an indirect bandgap semiconductor with a bandgap width of 2.58 eV. By extracting the exchange interaction intensities and magnetocrystalline anisotropy energy in a J1-J2-J3-K Heisenberg model, it was found that two-dimensional monolayer TaF4 possesses a Néel-type antiferromagnetic ground state and has a relatively high Néel temperature (208 K) and strong magnetocrystalline anisotropy energy (2.06 meV). These results are verified via the magnon spectrum. Full article
(This article belongs to the Special Issue Electronic, Optical and Magnetic Properties of Low-Dimensional Materials)
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<p>Unit cell (<b>a</b>), top (<b>b</b>), and side (<b>c</b>) views of atomic structure of 2D TaF4. Magenta and orange balls represent Ta and F atoms, respectively.</p> Full article ">Figure 2
<p>The phonon dispersion of the 2D TaF<sub>4</sub>. Blue (pink) lines represent the contribution of the Ta (F) atoms’ vibration.</p> Full article ">Figure 3
<p>The spin-polarized band structure of the 2D TaF<sub>4</sub> monolayer calculated with the high-accuracy HSE06 functional. The horizontal dotted line indicates the Fermi energy level.</p> Full article ">Figure 4
<p>Spin density isosurfaces of four different-magnetic-order structures: (<b>a</b>) FM, (<b>b</b>) AFM-1, (<b>c</b>) AFM-2, and (<b>d</b>) AFM-3. Yellow and blue isosurfaces indicate spin-up and spin-down densities, respectively. Exchange interactions of nearest-neighbor <span class="html-italic">J</span><sub>1</sub>, next nearest-neighbor <span class="html-italic">J</span><sub>2</sub>, and third nearest-neighbor <span class="html-italic">J</span><sub>3</sub> are pointed out in figure (<b>a</b>) with arrows.</p> Full article ">Figure 5
<p>Magnetocrystalline anisotropy energy of monolayer 2D TaF<sub>4</sub>.</p> Full article ">Figure 6
<p>Temperature dependence of magnetic moment (<b>a</b>) and Magnon spectra (<b>b</b>) of 2D TaF<sub>4</sub>.</p> Full article ">Figure 7
<p>Formation energy of 2D TaF<sub>4</sub> in convex hull of Ta-F compounds.</p> Full article ">
24 pages, 5331 KiB  
Review
Material Extrusion Additive Manufacturing of Ceramics: A Review on Filament-Based Process
by Roberto Spina and Luigi Morfini
Materials 2024, 17(11), 2779; https://doi.org/10.3390/ma17112779 - 6 Jun 2024
Cited by 2 | Viewed by 1976
Abstract
Additive manufacturing is very important due to its potential to build components and products using high-performance materials. The filament-based 3D printing of ceramics is investigated, revealing significant developments and advancements in ceramic material extrusion technology in recent years. Researchers employ several typologies of [...] Read more.
Additive manufacturing is very important due to its potential to build components and products using high-performance materials. The filament-based 3D printing of ceramics is investigated, revealing significant developments and advancements in ceramic material extrusion technology in recent years. Researchers employ several typologies of ceramics and binders to achieve fully dense products. The design of the filament and the necessary technological adaptations for 3D printing are fully investigated. From a material perspective, this paper reviews and analyzes the recent developments in additive manufacturing of material-extruded ceramics products, pointing out the performance and properties achieved with different material-binder combinations. The main gaps to be filled and recommendations for future developments in this field are reported. Full article
(This article belongs to the Special Issue Advances in 3D Printing/Additive Manufacturing Technology of Materials)
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<p>MEX processes are classified according to the extrusion method used: (<b>a</b>) filament-based, (<b>b</b>) plunger-based, and (<b>c</b>) screw-based extrusion [<a href="#B14-materials-17-02779" class="html-bibr">14</a>].</p> Full article ">Figure 2
<p>Shaping, Debinding, and Sintering process [<a href="#B14-materials-17-02779" class="html-bibr">14</a>].</p> Full article ">Figure 3
<p>Advantages and disadvantages of filament-based MEX process [<a href="#B39-materials-17-02779" class="html-bibr">39</a>].</p> Full article ">Figure 4
<p>SEM study of the fracture surface of sintered bars with layer thicknesses of (<b>a</b>) 0.3 mm, (<b>b</b>) 0.2 mm, (<b>c</b>) 0.1 mm, (<b>d</b>) anomalous alumina grain, (<b>e</b>) pore inside the filament, and (<b>f</b>) boundary between intergranular and transgranular fracture behavior (BSE) [<a href="#B22-materials-17-02779" class="html-bibr">22</a>].</p> Full article ">Figure 5
<p>SEM study of the fracture surface of bending sample with internal infill 100% [<a href="#B26-materials-17-02779" class="html-bibr">26</a>].</p> Full article ">Figure 6
<p>Print quality of calibration cubes in PLA (<b>left</b>) and 50% Al<sub>2</sub>O<sub>3</sub>/50% PLA (<b>right</b>) [<a href="#B24-materials-17-02779" class="html-bibr">24</a>].</p> Full article ">Figure 7
<p>Test specimens to evaluate the printability of ceramic filament. The close-up view shows printing defects [<a href="#B20-materials-17-02779" class="html-bibr">20</a>].</p> Full article ">Figure 8
<p>The bottom layer of sintered bending specimens with different raster orientations highlights principal defects found by [<a href="#B31-materials-17-02779" class="html-bibr">31</a>].</p> Full article ">Figure 9
<p>(<b>a</b>) SEM study of the fracture surface of the bending sample near the side of the bending sample. (<b>b</b>) enlarged image of the fracture surface [<a href="#B33-materials-17-02779" class="html-bibr">33</a>].</p> Full article ">Figure 10
<p>Picture of the printed 3D cup using YSZ Fabru filament after (<b>a</b>) shaping, (<b>b</b>) solvent debinding, (<b>c</b>) wick debinding, and (<b>d</b>) sintering. (<b>e</b>,<b>f</b>) show a cup printed using SiCeram filament showing cracks in the bottom area and between layers after solvent debinding [<a href="#B32-materials-17-02779" class="html-bibr">32</a>].</p> Full article ">Figure 11
<p>The printing process generated residual pores after MW 25 °C/min (adapted from [<a href="#B30-materials-17-02779" class="html-bibr">30</a>]).</p> Full article ">Figure 12
<p>SEM images of printed layer: (<b>a</b>) contour offset path; (<b>b</b>) parallel lines path; (<b>c</b>) grid path; (<b>d</b>) ground surface of the sintered part by grid printing path. Images of Si<sub>3</sub>N<sub>4</sub> parts prepared by MEX: (<b>e</b>) rectangular bar; (<b>f</b>) turbine rotor; (<b>g</b>) gear; (<b>h</b>) swirl fan [<a href="#B27-materials-17-02779" class="html-bibr">27</a>].</p> Full article ">Figure 13
<p>Sample realized from boron carbide (B<sub>4</sub>C) filament. Different infill value: (<b>a1</b>,<b>a2</b>) 20%, (<b>b1</b>,<b>b2</b>) 40%, (<b>c1</b>,<b>c2</b>) 60%, (<b>d1</b>,<b>d2</b>) 80%. Same sample after debinding and sintering at 2300 °C are shown with infill values of (<b>a3</b>,<b>a4</b>) 20%, (<b>b3</b>,<b>b4</b>) 40%, (<b>c3</b>,<b>c4</b>) 60%, (<b>d3</b>,<b>d4</b>) 80% [<a href="#B27-materials-17-02779" class="html-bibr">27</a>].</p> Full article ">
19 pages, 7243 KiB  
Article
Exploring In Vivo Pulmonary and Splenic Toxicity Profiles of Silicon Quantum Dots in Mice
by Roxana-Elena Cristian, Cornel Balta, Hildegard Herman, Alina Ciceu, Bogdan Trica, Beatrice G. Sbarcea, Eftimie Miutescu, Anca Hermenean, Anca Dinischiotu and Miruna S. Stan
Materials 2024, 17(11), 2778; https://doi.org/10.3390/ma17112778 - 6 Jun 2024
Viewed by 1082
Abstract
Silicon-based quantum dots (SiQDs) represent a special class of nanoparticles due to their low toxicity and easily modifiable surface properties. For this reason, they are used in applications such as bioimaging, fluorescent labeling, drug delivery, protein detection techniques, and tissue engineering despite a [...] Read more.
Silicon-based quantum dots (SiQDs) represent a special class of nanoparticles due to their low toxicity and easily modifiable surface properties. For this reason, they are used in applications such as bioimaging, fluorescent labeling, drug delivery, protein detection techniques, and tissue engineering despite a serious lack of information on possible in vivo effects. The present study aimed to characterize and evaluate the in vivo toxicity of SiQDs obtained by laser ablation in the lung and spleen of mice. The particles were administered in three different doses (1, 10, and 100 mg QDs/kg of body weight) by intravenous injection into the caudal vein of Swiss mice. After 1, 6, 24, and 72 h, the animals were euthanized, and the lung and spleen tissues were harvested for the evaluation of antioxidant enzyme activity, lipid peroxidation, protein expression, and epigenetic and morphological changes. The obtained results highlighted a low toxicity in pulmonary and splenic tissues for concentrations up to 10 mg SiQDs/kg body, demonstrated by biochemical and histopathological analysis. Therefore, our study brings new experimental evidence on the biocompatibility of this type of QD, suggesting the possibility of expanding research on the biomedical applications of SiQDs. Full article
(This article belongs to the Special Issue Development and Biomedical Applications of Optoelectronic Nanomaterials)
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<p>The characterization of SiQDs was achieved by SEM (<b>a</b>) and TEM (<b>b</b>) analysis. The spherical shape of QDs is marked by white dot circles (<b>b</b>).</p> Full article ">Figure 2
<p>Histopathological evaluation of lung tissue using hematoxylin and eosin staining at intervals of 1, 6, 24, and 72 h post administration of 1 mg, 10 mg, and 100 mg of SiQDs/kg of b.w. Legend: arrows—alveolar macrophages; black stars—SiQD accumulation (brown). Scale bar (represented in the lower right corner of each image): 20 µm.</p> Full article ">Figure 3
<p>Histopathological evaluation of spleen tissue using hematoxylin and eosin staining at intervals of 1, 6, 24, and 72 h post administration of 1 mg, 10 mg, and 100 mg of SiQDs/kg of b.w. Details for 100 mg QDs/kg b.w. show the SiQD accumulation (brown dots evidenced by stars). Scale bar: 50 µm.</p> Full article ">Figure 4
<p>Specific activities of SOD (<b>a</b>,<b>b</b>), CAT (<b>c</b>,<b>d</b>), Gred (<b>e</b>,<b>f</b>), GPx (<b>g</b>,<b>h</b>), and GST (<b>i</b>,<b>j</b>) in lung (<b>a</b>,<b>c</b>,<b>e</b>,<b>g</b>,<b>i</b>) and spleen (<b>b</b>,<b>d</b>,<b>f</b>,<b>h</b>,<b>j</b>) tissues collected at 1, 6, 24, and 72 h after SiQD administration. Results are calculated as mean ± SD (<span class="html-italic">n</span> = 5) and are represented relative to the control. * <span class="html-italic">p</span> &lt; 0.05, ** <span class="html-italic">p</span> &lt; 0.01, and *** <span class="html-italic">p</span> &lt; 0.001 compared to control.</p> Full article ">Figure 5
<p>Levels of GSH (<b>a</b>,<b>b</b>) and MDA (<b>c</b>,<b>d</b>) in lung (<b>a</b>,<b>c</b>) and spleen (<b>b</b>,<b>d</b>) tissues collected at 1, 6, 24, and 72 h after SiQD administration. Results are calculated as mean ± SD (<span class="html-italic">n</span> = 5) and are represented relative to the control. * <span class="html-italic">p</span> &lt; 0.05, ** <span class="html-italic">p</span> &lt; 0.01, and *** <span class="html-italic">p</span> &lt; 0.001 compared to control.</p> Full article ">Figure 6
<p>Changes in proteins’ expression involved in antioxidative defense response, apoptosis, and autophagy after SiQD administration (100 mg/kg b.w.) to mice. The analysis of Nrf-2, p53 Beclin-1, and LC-3 protein expression by Western blot (<b>a</b>) was quantified in the lung (<b>b</b>,<b>d</b>,<b>f</b>,<b>h</b>) and spleen (<b>c</b>,<b>e</b>,<b>g</b>,<b>i</b>) tissues collected at 1, 6, 24, and 72 h after SiQD administration. Results are calculated as mean ± SD (<span class="html-italic">n</span> = 5) and are represented relative to the control. * <span class="html-italic">p</span> &lt; 0.05 compared with the control.</p> Full article ">Figure 6 Cont.
<p>Changes in proteins’ expression involved in antioxidative defense response, apoptosis, and autophagy after SiQD administration (100 mg/kg b.w.) to mice. The analysis of Nrf-2, p53 Beclin-1, and LC-3 protein expression by Western blot (<b>a</b>) was quantified in the lung (<b>b</b>,<b>d</b>,<b>f</b>,<b>h</b>) and spleen (<b>c</b>,<b>e</b>,<b>g</b>,<b>i</b>) tissues collected at 1, 6, 24, and 72 h after SiQD administration. Results are calculated as mean ± SD (<span class="html-italic">n</span> = 5) and are represented relative to the control. * <span class="html-italic">p</span> &lt; 0.05 compared with the control.</p> Full article ">Figure 7
<p>The levels of 8-OHdG (<b>a</b>) and global DNA methylation (<b>b</b>) determined by ELISA technique in the murine lung and spleen samples collected at 72 h after the administration of SiQDs (100 mg QDs/kg b.w.). Results are expressed as mean ± SD (<span class="html-italic">n</span> = 5).</p> Full article ">Figure 8
<p>Changes in histone H4 in lung (<b>a</b>) and spleen (<b>b</b>) samples collected 72 h after SiQD administration (100 mg QDs/kg b.w.).</p> Full article ">
13 pages, 1290 KiB  
Article
Mechanical Properties of Alkasite Material with Different Curing Modes and Simulated Aging Conditions
by Visnja Negovetic Mandic, Laura Plancak, Danijela Marovic, Zrinka Tarle, Milena Trutina Gavran and Matej Par
Materials 2024, 17(11), 2777; https://doi.org/10.3390/ma17112777 - 6 Jun 2024
Viewed by 1013
Abstract
This study aimed to evaluate the micro-mechanical and macro-mechanical properties of self-cured and light-cured alkasite and to investigate how accelerated degradation in acidic, alkaline, and ethanol solutions affects the macro-mechanical properties of self-cured and light-cured alkasite. The specimens of the alkasite material (Cention [...] Read more.
This study aimed to evaluate the micro-mechanical and macro-mechanical properties of self-cured and light-cured alkasite and to investigate how accelerated degradation in acidic, alkaline, and ethanol solutions affects the macro-mechanical properties of self-cured and light-cured alkasite. The specimens of the alkasite material (Cention Forte, Ivoclar Vivadent) were prepared according to the following three curing modes: (1) light-cured immediately, (2) light-cured after a 5-min delay, and (3) self-cured. Microhardness was tested before and after immersion in absolute ethanol to indirectly determine crosslink density, while flexural strength and flexural modulus were measured using a three-point bending test after accelerated aging in the following solutions: (1) lactic acid solution (pH = 4.0), (2) NaOH solution (pH = 13.0), (3) phosphate-buffered saline solution (pH = 7.4), and (4) 75% ethanol solution. The data were statistically analyzed using a two-way ANOVA and Tukey post hoc test. The results showed that the microhardness, flexural strength, and flexural modulus were significantly lower in self-cured specimens compared to light-cured specimens. A 5-min delay between the extrusion of the material from the capsule and light curing had no significant effect on any of the measured properties. A significant effect of the accelerated aging solutions on macro-mechanical properties was observed, with ethanol and alkaline solutions having a particularly detrimental effect. In conclusion, light curing was preferable to self-curing, as it resulted in significantly better micro- and macro-mechanical properties, while a 5-min delay between mixing the capsule and light curing had no negative effects. Full article
(This article belongs to the Special Issue Biomaterials for Restorative Dentistry)
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<p>Mean values and standard deviations of initial microhardness (<b>a</b>), final microhardness (<b>b</b>), and the ratio between final and initial microhardness (<b>c</b>). Statistically similar values (<span class="html-italic">p</span> &gt; 0.05) for comparisons among layer thicknesses are marked with the same uppercase letters (light-cured specimens), lowercase letters (delayed light-cured specimens), and Greek letters (self-cured specimens). Square brackets indicate statistically similar values (<span class="html-italic">p</span> &gt; 0.05) for comparisons among different curing modes within each layer thickness.</p> Full article ">Figure 2
<p>Mean values and standard deviations of flexural strength (<b>a</b>) and flexural modulus (<b>b</b>). Statistically similar values (<span class="html-italic">p</span> &gt; 0.05) for comparisons among immersion media are marked with same uppercase letters (light-cured specimens), lowercase letters (delayed light-cured specimens), and Greek letters (self-cured specimens). Square brackets indicate statistically similar values (<span class="html-italic">p</span> &gt; 0.05) for comparisons among different curing modes within each immersion medium.</p> Full article ">Figure 3
<p>Weibull plots in which material reliability is represented as slopes of fit lines.</p> Full article ">
21 pages, 4302 KiB  
Article
Thermophysical Properties of FUNaK (NaF-KF-UF4) Eutectics
by Maxime Fache, Laura Voigt, Jean-Yves Colle, John Hald and Ondřej Beneš
Materials 2024, 17(11), 2776; https://doi.org/10.3390/ma17112776 - 6 Jun 2024
Viewed by 1288
Abstract
General interest in the deployment of molten salt reactors (MSRs) is growing, while the available data on uranium-containing fuel salt candidates remains scarce. Thermophysical data are one of the key parameters for reactor design and understanding reactor operability. Hence, filling in the gap [...] Read more.
General interest in the deployment of molten salt reactors (MSRs) is growing, while the available data on uranium-containing fuel salt candidates remains scarce. Thermophysical data are one of the key parameters for reactor design and understanding reactor operability. Hence, filling in the gap of the missing data is crucial to allow for the advancement of MSRs. This study provides novel data for two eutectic compositions within the NaF-KF-UF4 ternary system which serve as potential fuel candidates for MSRs. Experimental measurements include their melting point, density, fusion enthalpy, and vapor pressure. Additionally, their boiling point was extrapolated from the vapor pressure data, which were, at the same time, used to determine the enthalpy of vaporization. The obtained thermodynamic values were compared with available data from the literature but also with results from thermochemical equilibrium calculations using the JRCMSD database, finding a good correlation, which thus contributed to database validation. Preliminary thoughts on fluoride salt reactor operability based on the obtained results are discussed in this study. Full article
(This article belongs to the Special Issue Recent Advances in Materials for Molten Salt Nuclear Reactor Technology)
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<p>Density setup [<a href="#B25-materials-17-02776" class="html-bibr">25</a>].</p> Full article ">Figure 2
<p>DSC outputs of the heat flow measured for (<b>a</b>) FUNaK #1 (NaF-KF-UF<sub>4</sub> (55.6-18.7-25.7 mol%)) and (<b>b</b>) FUNaK #2 (NaF-KF-UF<sub>4</sub> (50.4-23.2-26.4 mol%)). The heating rates considered are 2 and 10 K/min. The two first peaks correspond to solid-state transitions, while the melting point is determined as the onset temperature of the last peak. Temperature values are corrected. Exothermic transitions are going up, by convention.</p> Full article ">Figure 3
<p>DSC outputs of the measurement of the enthalpy of fusion of (<b>a</b>) NaF-KF-UF<sub>4</sub> (55.6-18.7-25.7 mol%) (FUNaK #1) and (<b>b</b>) NaF-KF-UF<sub>4</sub> (50.4-23.2-26.4 mol%) (FUNaK #2).</p> Full article ">Figure 4
<p>Densities comparison of the NaF-KF-UF<sub>4</sub> eutectic composition (FUNaK #1) and NaF-KF-UF<sub>4</sub> eutectic composition (FUNaK #2) in blue triangle dots and red square dots, with the MD model [<a href="#B31-materials-17-02776" class="html-bibr">31</a>] in blue and red lines and the ideal mixture in blue and red dashed lines respectively. Other experimental results from Park et al. [<a href="#B10-materials-17-02776" class="html-bibr">10</a>] in yellow star dots and Cohen and Jones [<a href="#B16-materials-17-02776" class="html-bibr">16</a>] in purple diamond dots and green circle dots for other compositions are plotted for comparison. A 4% uncertainty is considered for the experimental results in this study, while a 2% uncertainty band is displayed for the MD model.</p> Full article ">Figure 5
<p>Appearance potentials of end members of FUNaK #2 at T = 1230 K. (<b>a</b>) KF; (<b>b</b>) NaF; (<b>c</b>) UF<sub>4</sub>.</p> Full article ">Figure 6
<p>Partial and total vapor pressures of NaF-KF-UF<sub>4</sub> (55.6-18.7-25.7 mol%)’s composition (FUNaK #1) and of NaF-KF-UF<sub>4</sub> (50.4-23.2-26.4 mol%)’s composition (FUNaK #2). The total vapor pressure and species vapor pressures for FUNaK #2 calculated from the quasi-chemical (QC) model from Ocádiz et al. [<a href="#B11-materials-17-02776" class="html-bibr">11</a>] are also plotted.</p> Full article ">Figure 7
<p>Vapor pressure extrapolation of NaF-KF-UF<sub>4</sub> (55.6-18.7-25.7 mol%) (FUNaK #1), as a black curved line; NaF-KF-UF<sub>4</sub> (50.4-23.2-26.4 mol%) (FUNaK #2) from the experiment, as a grey curved line; and of the model based on FUNaK #2’s composition [<a href="#B11-materials-17-02776" class="html-bibr">11</a>], as a dashed black line. The red dashed lines are the linear vapor pressure extrapolation of UF<sub>4(g)</sub> for FUNaK #1 and FUNaK #2 while the grey dashed lines are the linear total vapor pressure extrapolation for FUNaK #1 and FUNaK #2, showing the higher contribution of UF<sub>4(g)</sub> at higher temperature. The boiling point, T<sub>B</sub>, determined for the experiments and the FUNaK model are also displayed. T<sub>B</sub> (FUNaK #1): diamond dot; T<sub>B</sub> (FUNaK #2): triangle dot; T<sub>B</sub> (FUNaK model): star dot. In the red circle a zoom of the graph is shown for a better identification of the boiling points.</p> Full article ">Figure 8
<p>Enthalpy of vaporization evolution with temperature for FUNaK eutectic compositions in blue square dots (FUNaK #1) and in red circle dots (FUNaK #2) and the FUNaK model in gray line and in black line. The dashed black circle indicates the starting temperature for all the curves (T = 298 K). The models for FUNaK #1 [<a href="#B11-materials-17-02776" class="html-bibr">11</a>] and FUNaK #2 [<a href="#B11-materials-17-02776" class="html-bibr">11</a>] are visually the same. An uncertainty of 20% was considered.</p> Full article ">Figure 9
<p>DSC outputs of the heat flow measured for FUNaK compositions (<b>a</b>) close to FUNaK #1’s composition (NaF-KF-UF<sub>4</sub> (55.6-18.7-25.7 mol%)) and (<b>b</b>) close to FUNaK #2’s composition (NaF-KF-UF<sub>4</sub> (50.4-23.2-26.4 mol%)). The considered heating rates are 2 K/min. Exothermic transitions are going up, by convention [<a href="#B11-materials-17-02776" class="html-bibr">11</a>].</p> Full article ">
27 pages, 9024 KiB  
Article
Experimental Analysis of Effect of Machined Material on Cutting Forces during Drilling
by Josef Sklenička, Jan Hnátík, Jaroslava Fulemová, Miroslav Gombár, Alena Vagaská and Aneta Jirásko
Materials 2024, 17(11), 2775; https://doi.org/10.3390/ma17112775 - 6 Jun 2024
Viewed by 945
Abstract
Current research studies devoted to cutting forces in drilling are oriented toward predictive model development, however, in the case of mechanistic models, the material effect on the drilling process itself is mostly not considered. This research study aims to experimentally analyze how the [...] Read more.
Current research studies devoted to cutting forces in drilling are oriented toward predictive model development, however, in the case of mechanistic models, the material effect on the drilling process itself is mostly not considered. This research study aims to experimentally analyze how the machined material affects the feed force (Ff) during drilling, alongside developing predictive mathematical–statistical models to understand the main effects and interactions of the considered technological and tool factors on Ff. By conducting experiments involving six factors (feed, cutting speed, drill diameter, point angle, lip relief angle, and helix angle) at five levels, the drilling process of stainless steel AISI1045 and case-hardened steel 16MnCr5 is executed to validate the numerical accuracy of the established prediction models (AdjR = 99.600% for C45 and AdjR = 97.912% for 16MnCr5). The statistical evaluation (ANOVA, RSM, and Lack of Fit) of the data proves that the drilled material affects the Ff value at the level of 17.600% (p < 0.000). The effect of feed represents 44.867% in C45 and 34.087% in 16MnCr5; the cutting speed is significant when machining C45 steel only (9.109%). When machining 16MnCr5 compared to C45 steel, the influence of the point angle (lip relief angle) is lower by 49.198% (by 22.509%). The effect of the helix angle is 163.060% higher when machining 16MnCr5. Full article
(This article belongs to the Special Issue Precision and Ultra-Precision Subtractive and Additive Manufacturing Processes of Alloys and Steels, 2nd Edition)
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Figure 1
<p>The standard nomenclature of a helical drill (1—axis, 2—shank or clamping part (conical, smooth cylindrical, or smooth cylindrical with a driver), 3—tang, 4—driver, 5—the drill body, 6—neck, 7—total length, 8—helix length of the groove, 9—groove, 10—body clearance surface, 11—the width of body clearance surface, 12—web (core), 13—web diameter, 14—margin, 15—margin width, 16—side cutting edge, 17—land relief, 18—land relief depth, 19—heel, 20—flank, 21—face, 22—main cutting edge, 23—wedge, 24—drill tip, 25—chisel, 26—chisel edge length, 27—main cutting edge length, 28—nominal tool diameter, 29—diameter of the relief, 30—reverse taper, 31—helix pitch, 32—helix angle, 33—chisel edge angle, 34—point angle, and 35—lip relief angle).</p> Full article ">Figure 2
<p>Microstructure of the used C45 steel samples.</p> Full article ">Figure 3
<p>Microstructure of the used steel 16MnCr5.</p> Full article ">Figure 4
<p>Photographs from experimental verification. (<b>a</b>) Machine and (<b>b</b>) workpiece clamped on the dynamometer.</p> Full article ">Figure 5
<p>The impact of feed <span class="html-italic">f<sub>n</sub></span> and cutting speed <span class="html-italic">v<sub>c</sub></span> on the change in the value of the feed force <span class="html-italic">F<sub>f</sub></span> (response) for the drilled material C45. (<b>a</b>) <span class="html-italic">D</span> = 8 mm and (<b>b</b>) <span class="html-italic">D</span> = 12 mm.</p> Full article ">Figure 6
<p>The effect of the cutting speed (<span class="html-italic">v<sub>c</sub></span>) and the point angle (<span class="html-italic">ε<sub>r</sub></span>) on the change in the value of response <span class="html-italic">F<sub>f</sub></span> for the drilled material C45 when setting (<b>a</b>) <span class="html-italic">f<sub>n</sub></span> = 0.09 mm·rev<sup>−1</sup> and (<b>b</b>) <span class="html-italic">f<sub>n</sub></span> = 0.26 mm·rev<sup>−1</sup>.</p> Full article ">Figure 7
<p>The effect of the point angle (<span class="html-italic">ε<sub>r</sub></span>) and the helix angle (<span class="html-italic">ω<sub>r</sub></span>) on the changes in the feed force (<span class="html-italic">F<sub>f</sub></span>) values for the drilled material C45 when setting (<b>a</b>) <span class="html-italic">v<sub>c</sub></span> = 80.21 m·min<sup>−1</sup> and (<b>b</b>) <span class="html-italic">v<sub>c</sub></span> = 149.79 m·min<sup>−1</sup>.</p> Full article ">Figure 8
<p>The impact of feed <span class="html-italic">f<sub>n</sub></span> and cutting speed <span class="html-italic">v<sub>c</sub></span> on the change in the value of the feed force <span class="html-italic">F<sub>f</sub></span> for the drilled material 16MnCr5 using drill diameter of (<b>a</b>) <span class="html-italic">D</span> = 8 mm and (<b>b</b>) <span class="html-italic">D</span> = 12 mm.</p> Full article ">Figure 9
<p>The effect of the feed <span class="html-italic">f<sub>n</sub></span> and the drill diameter <span class="html-italic">D</span> on the changes in the feed force (<span class="html-italic">F<sub>f</sub></span>) values for the drilled material 16MnCr5 when applying helix angle (<b>a</b>) <span class="html-italic">ω<sub>r</sub></span> = 25.00° and (<b>b</b>) <span class="html-italic">ω<sub>r</sub></span> = 35.00°.</p> Full article ">Figure 10
<p>The impact of the point angle (<span class="html-italic">ε<sub>r</sub></span>) and the helix angle (<span class="html-italic">ω<sub>r</sub></span>) on the change in the response value of <span class="html-italic">F<sub>f</sub></span> for the drilled material 16MnCr5. (<b>a</b>) <span class="html-italic">v<sub>c</sub></span> = 80.21 m·min<sup>−1</sup> and (<b>b</b>) <span class="html-italic">v<sub>c</sub></span> = 149.79 m·min<sup>−1</sup>.</p> Full article ">Figure 11
<p>A relative error of the model predicting the feed component of the cutting force (<span class="html-italic">F<sub>f</sub></span>) when drilling the material C45. (<b>a</b>) model (2) and (<b>b</b>) model (4).</p> Full article ">Figure 12
<p>A relative error of the model predicting the feed force (<span class="html-italic">F<sub>f</sub></span>) when drilling the material 16MnCr5. (<b>a</b>) model (2) and (<b>b</b>) developed model (5).</p> Full article ">Figure 13
<p>The influence of selected technological (<span class="html-italic">f<sub>n</sub></span> and <span class="html-italic">v<sub>c</sub></span>) and tool (<span class="html-italic">D</span>) factors on the change in the value of the feed force (<span class="html-italic">F<sub>f</sub></span>) when setting (<b>a</b>) <span class="html-italic">v<sub>c</sub></span> = 80.21 m·min<sup>−1</sup>, <span class="html-italic">D</span> = 8.00 mm; (<b>b</b>) <span class="html-italic">v<sub>c</sub></span> = 149.79 m·min<sup>−1</sup>, <span class="html-italic">D</span> = 8.00 mm; (<b>c</b>) <span class="html-italic">v<sub>c</sub></span> = 80.21 m·min<sup>−1</sup>, <span class="html-italic">D</span> = 12.00 mm; and (<b>d</b>) <span class="html-italic">v<sub>c</sub></span> = 149.79 m·min<sup>−1</sup>, <span class="html-italic">D</span> = 12.00 mm.</p> Full article ">
37 pages, 8988 KiB  
Review
Encapsulation of Active Substances in Natural Polymer Coatings
by Emma Akpo, Camille Colin, Aurélie Perrin, Julien Cambedouzou and David Cornu
Materials 2024, 17(11), 2774; https://doi.org/10.3390/ma17112774 - 6 Jun 2024
Cited by 4 | Viewed by 1744
Abstract
Already used in the food, pharmaceutical, cosmetic, and agrochemical industries, encapsulation is a strategy used to protect active ingredients from external degradation factors and to control their release kinetics. Various encapsulation techniques have been studied, both to optimise the level of protection with [...] Read more.
Already used in the food, pharmaceutical, cosmetic, and agrochemical industries, encapsulation is a strategy used to protect active ingredients from external degradation factors and to control their release kinetics. Various encapsulation techniques have been studied, both to optimise the level of protection with respect to the nature of the aggressor and to favour a release mechanism between diffusion of the active compounds and degradation of the barrier material. Biopolymers are of particular interest as wall materials because of their biocompatibility, biodegradability, and non-toxicity. By forming a stable hydrogel around the drug, they provide a ‘smart’ barrier whose behaviour can change in response to environmental conditions. After a comprehensive description of the concept of encapsulation and the main technologies used to achieve encapsulation, including micro- and nano-gels, the mechanisms of controlled release of active compounds are presented. A panorama of natural polymers as wall materials is then presented, highlighting the main results associated with each polymer and attempting to identify the most cost-effective and suitable methods in terms of the encapsulated drug. Full article
(This article belongs to the Section Green Materials)
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Figure 1

Figure 1
<p>Different types of microcapsule architectures: (<b>A</b>) simple microcapsule, (<b>B</b>) microsphere, (<b>C</b>) multiwall microcapsule, (<b>D</b>) multicore microcapsule, (<b>E</b>) irregular microcapsule, (<b>F</b>) assembly of microcapsules, polymer layer are represented in black and dark grey and the light grey represents the active substance, inspired by [<a href="#B20-materials-17-02774" class="html-bibr">20</a>].</p> Full article ">Figure 2
<p>Scheme of the spray-drying process for encapsulation of active ingredients, (<b>A</b>) tank containing the sprayed mixture: polymer and active ingredient, (<b>B</b>) pump to feed the mixture in the system, (<b>C</b>) spray nozzle, (<b>D</b>) heater to heat up the airflow, (<b>E</b>) chamber, (<b>F</b>) cyclone separator, and (<b>G</b>) spray dried capsules, inspired by [<a href="#B4-materials-17-02774" class="html-bibr">4</a>].</p> Full article ">Figure 3
<p>Scheme of the extrusion process, (<b>A</b>) Syringe, (<b>B</b>) Polymer (alginate) solution, (<b>C</b>) Syringe needle, (<b>D</b>) Gelling bath (with calcium chloride), and (<b>E</b>) Syringe pump, inspired by [<a href="#B11-materials-17-02774" class="html-bibr">11</a>].</p> Full article ">Figure 4
<p>Mechanism of microencapsulation formation by the coacervation method, (<b>A</b>) suspension of the core material (dark grey circles) in the liquid phase (light grey background), (<b>B</b>) suspension of the polymer (small black circles) in the liquid phase, (<b>C</b>) adsorption of the polymer material onto the core material, and (<b>D</b>) gelation and solidification of the microcapsule wall (black layer surrounding the dark grey circles), inspired by [<a href="#B15-materials-17-02774" class="html-bibr">15</a>].</p> Full article ">Figure 5
<p>Mechanism of gum-based micro- and nanoparticle formations: Ionotropic gelation, inspired by [<a href="#B56-materials-17-02774" class="html-bibr">56</a>].</p> Full article ">Figure 6
<p>Mechanism of gum-based micro- and nanoparticle formations: Covalent cross-linking, inspired by [<a href="#B56-materials-17-02774" class="html-bibr">56</a>].</p> Full article ">Figure 7
<p>Mechanism of gum-based micro- and nanoparticle formations: Polyelectrolyte complexation, inspired by [<a href="#B56-materials-17-02774" class="html-bibr">56</a>].</p> Full article ">Figure 8
<p>Mechanism of gum-based micro- and nanoparticle formations: Drug or hydrophobic agent/polymer conjugation with self-assembly, inspired by [<a href="#B56-materials-17-02774" class="html-bibr">56</a>].</p> Full article ">Figure 9
<p>Mechanism of gum-based micro- and nanoparticle formations: Self-assembly of amphoteric molecular compounds, inspired by [<a href="#B56-materials-17-02774" class="html-bibr">56</a>].</p> Full article ">Figure 10
<p>Mechanisms of the release of active substances, from polymer coatings, (<b>A</b>) initial encapsulation system, (<b>B</b>) fragmentation, (<b>C</b>) swelling, (<b>D</b>) diffusion, (<b>E</b>) degradation, and (<b>F</b>) dissolution, inspired by [<a href="#B4-materials-17-02774" class="html-bibr">4</a>].</p> Full article ">Figure 11
<p>Plot of the hydrodynamic radius of poly (N-isopropylacrylamide-co-acrylic acid) polymer microgel according to the temperature at different pH values. Reproduced with permission from Farooqi et al., Arab. J. Chem.; published by Elsevier, 2017 [<a href="#B83-materials-17-02774" class="html-bibr">83</a>].</p> Full article ">Figure 12
<p>Molecular structure of sodium alginate.</p> Full article ">Figure 13
<p>“Egg box” model for calcium alginate, Reproduced with permission from Finotelli et al., Polimeros; published by ABPol, 2017 [<a href="#B90-materials-17-02774" class="html-bibr">90</a>].</p> Full article ">Figure 14
<p>Molecular structure of pectin: homogalacturonan structure.</p> Full article ">Figure 15
<p>Molecular structure of amylose.</p> Full article ">Figure 16
<p>Molecular structure of amylopectin.</p> Full article ">Figure 17
<p>Molecular structure of κ-carrageenan.</p> Full article ">Figure 18
<p>Stability and release characteristics of release of phage encapsulated inside microcapsules by in vitro digestion, (<b>A</b>) pure ALG microcapsules. (<b>B</b>) AC microcapsules AC1–AC9 represent polysaccharide mixtures in different proportions. (AC1) 1%ALG and 0.15%CG, (AC2) 1.5%ALG and 0.15%CG, (AC3) 2%ALG and 0.15%CG, (AC4) 1%ALG and 0.3%CG, (AC5) 1.5%ALG and 0.3%CG, (AC6) 2%ALG and 0.3%CG, (AC7) 1%ALG and 0.45%CG, (AC8) 1.5%ALG and 0.45%CG, (AC9) 2%ALG, and 0.45%CG. Reproduced with permission from Zhou et al., Front. Microbiol.; published by Frontiers, 2022 [<a href="#B109-materials-17-02774" class="html-bibr">109</a>].</p> Full article ">Figure 18 Cont.
<p>Stability and release characteristics of release of phage encapsulated inside microcapsules by in vitro digestion, (<b>A</b>) pure ALG microcapsules. (<b>B</b>) AC microcapsules AC1–AC9 represent polysaccharide mixtures in different proportions. (AC1) 1%ALG and 0.15%CG, (AC2) 1.5%ALG and 0.15%CG, (AC3) 2%ALG and 0.15%CG, (AC4) 1%ALG and 0.3%CG, (AC5) 1.5%ALG and 0.3%CG, (AC6) 2%ALG and 0.3%CG, (AC7) 1%ALG and 0.45%CG, (AC8) 1.5%ALG and 0.45%CG, (AC9) 2%ALG, and 0.45%CG. Reproduced with permission from Zhou et al., Front. Microbiol.; published by Frontiers, 2022 [<a href="#B109-materials-17-02774" class="html-bibr">109</a>].</p> Full article ">Figure 19
<p>Molecular structure of high acyl gellan.</p> Full article ">Figure 20
<p>Molecular structure of low acyl gellan.</p> Full article ">Figure 21
<p>Percentage change in bead size (%) after 24 h of immersion in different pH solutions. Values are shown with the standard deviation. Adapted from [<a href="#B40-materials-17-02774" class="html-bibr">40</a>].</p> Full article ">Figure 22
<p>Molecular structure of xanthan gum.</p> Full article ">Figure 23
<p>Molecular structure of gum arabic.</p> Full article ">Figure 24
<p>Molecular structure of guar gum.</p> Full article ">Figure 25
<p>Molecular structure of agarose.</p> Full article ">Figure 26
<p>Maltodextrin (<b>left</b>) and cyclodextrin (<b>right</b>) molecular structures.</p> Full article ">Figure 27
<p>Morphology of lime essential oil microparticles: Encapsulation by spray drying method of lime essential oils in whey protein concentrate, whey protein blended/maltodextrin DE5 (WM5), whey protein blended/maltodextrin DE10 (WM10), and whey protein blended/maltodextrin DE10 (WM20). Reproduced with permission from Campello et al., Food Res. Int.; published by Elsevier, 2018 [<a href="#B134-materials-17-02774" class="html-bibr">134</a>].</p> Full article ">Figure 28
<p>Molecular structure of locust bean gum.</p> Full article ">Figure 29
<p>Characterisation of the controlled release of Capecitabine in vitro, plasma drug concentration versus time profile of the Capecitabine encapsulated in locust bean gum/alginate microbeads, vertical bars represent mean ± S.D. (standard deviation), the total number of values is 6. Reproduced with permission from Upadhyay et al. Mater. Sci. Eng. C; published by Elsevier, 2019 [<a href="#B7-materials-17-02774" class="html-bibr">7</a>].</p> Full article ">Figure 30
<p>Molecular structure of chitin and chitosan.</p> Full article ">Figure 31
<p>Molecular structure of gelatin.</p> Full article ">Figure 32
<p>Molecular structure of casein.</p> Full article ">Figure 33
<p>Total phenolic content of blueberry polyphenol-protein matrices, the scavenging capacity of different combinations of blueberry polyphenol-protein matrices obtained by different entrapment methods: Freeze drying, oven drying, and spray drying (total phenolic content (TPC) calculated as mg gallic acid equivalent). Bars with different letters (a,b,c) are significantly different by Tukey’s test (2-way ANOVA) test, <span class="html-italic">p</span> &lt; 0.01. Reproduced with permission from Correia et al. Food Chem.; published by Elsevier, 2017 [<a href="#B163-materials-17-02774" class="html-bibr">163</a>].</p> Full article ">
10 pages, 2566 KiB  
Article
The Effect of Sputtering Sequence Engineering in Superlattice-like Sb-Rich-Based Phase Change Materials
by Anding Li, Ruirui Liu, Liu Liu, Yukun Chen and Xiao Zhou
Materials 2024, 17(11), 2773; https://doi.org/10.3390/ma17112773 - 6 Jun 2024
Cited by 1 | Viewed by 870
Abstract
This paper presents a comprehensive investigation into the thermal stability of superlattice-like (SLL) thin films fabricated by varying the sputtering sequences of the SLL [Ge8Sb92(25nm)/GeTe(25nm)]1 and SLL [GeTe(25nm)/Ge8Sb92(25nm)]1 configurations. Our results reveal significantly [...] Read more.
This paper presents a comprehensive investigation into the thermal stability of superlattice-like (SLL) thin films fabricated by varying the sputtering sequences of the SLL [Ge8Sb92(25nm)/GeTe(25nm)]1 and SLL [GeTe(25nm)/Ge8Sb92(25nm)]1 configurations. Our results reveal significantly enhanced ten-year data retention (Tten) for both thin films measured at 124.3 °C and 151.9 °C, respectively. These values surpass the Tten of Ge2Sb2Te5 (85 °C), clearly demonstrating the superior thermal stability of the studied SLL configurations. Interestingly, we also observe a distinct difference in the thermal stability between the two SLL configurations. The superior thermal stability of SLL [GeTe(25nm)/Ge8Sb92(25nm)]1 is attributed to the diffusion of the Sb precipitated phase from Ge8Sb92 to GeTe. This diffusion process effectively reduces the impact of the Sb phase on the thermal stability of the thin film. In contrast, in the case of SLL [Ge8Sb92(25nm)/GeTe(25nm)]1, the presence of the Sb precipitated phase in Ge8Sb92 facilitates the crystallization of GeTe, leading to reduced thermal stability. These findings underscore the significant influence of the sputtering sequence on the atomic behavior and thermal properties of superlattice-like phase change materials. Such insights provide a robust foundation for the design and exploration of novel phase change materials with improved thermal performance. Full article
(This article belongs to the Topic Advances in Energy Storage Materials/Devices and Solid-State Batteries)
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Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>(<b>a</b>) Temperature-dependent sheet resistance curves of SLL GS/GT and SLL GT/GS at a heating rate of 10 °C/min. (<b>b</b>) The structural schematic of SLL GS/GT and SLL GT/GS.</p> Full article ">Figure 2
<p>The Kissinger plots in <math display="inline"><semantics> <mrow> <mo>[</mo> <mo>(</mo> <mi>d</mi> <mi>T</mi> <mo>/</mo> <mi>d</mi> <mi>t</mi> <mo>)</mo> <mo>/</mo> <msubsup> <mrow> <mi>T</mi> </mrow> <mrow> <mi>c</mi> </mrow> <mrow> <mn>2</mn> </mrow> </msubsup> <mo>]</mo> </mrow> </semantics></math> versus 1/<math display="inline"><semantics> <mrow> <mi>k</mi> <mi>T</mi> </mrow> </semantics></math> of SLL GS/GT (<b>a</b>) and SLL GT/GS (<b>b</b>) thin films. Illustration includes the temperature-dependent thin-layer resistance curves of SLL GS/GT and SLL GT/GS thin films with different heating rates.</p> Full article ">Figure 3
<p>Failure time versus reciprocal temperature of SLL GS/GT (<b>a</b>) and SLL GT/GS (<b>b</b>).</p> Full article ">Figure 4
<p>Raman spectra of SLL GS/GT (<b>left</b>) and GT/GS (<b>right</b>) at various annealing temperatures for 3 min.</p> Full article ">Figure 5
<p>XRD plots of SLL GS/GT (<b>a</b>) and SLL GT/GS (<b>b</b>) at various annealing temperatures for 3 min.</p> Full article ">Figure 6
<p>Three-dimensional AFM topographic images of Ge8Sb92: (<b>a</b>) As-deposited; (<b>b</b>) Annealed at 130 °C for 3 min; (<b>c</b>) Annealed at 160 °C for 3 min; (<b>d</b>) Annealed at 190 °C for 3 min. Three-dimensional AFM topographic images of GeTe: (<b>e</b>) As-deposited; (<b>f</b>) Annealed at 190 °C for 3 min.</p> Full article ">
18 pages, 10855 KiB  
Article
Nondestructive Inspection and Quantification of Select Interface Defects in Honeycomb Sandwich Panels
by Mahsa Khademi, Daniel P. Pulipati and David A. Jack
Materials 2024, 17(11), 2772; https://doi.org/10.3390/ma17112772 - 6 Jun 2024
Cited by 1 | Viewed by 1060
Abstract
Honeycomb sandwich panels are utilized in many industrial applications due to their high bending resistance relative to their weight. Defects between the core and the facesheet compromise their integrity and efficiency due to the inability to transfer loads. The material system studied in [...] Read more.
Honeycomb sandwich panels are utilized in many industrial applications due to their high bending resistance relative to their weight. Defects between the core and the facesheet compromise their integrity and efficiency due to the inability to transfer loads. The material system studied in the present paper is a unidirectional carbon fiber composite facesheet with a honeycomb core with a variety of defects at the interface between the two material systems. Current nondestructive techniques focus on defect detectability, whereas the presented method uses high-frequency ultrasound testing (UT) to detect and quantify the defect geometry and defect type. Testing is performed using two approaches, a laboratory scale immersion tank and a novel portable UT system, both of which utilize only single-side access to the part. Coupons are presented with defects spanning from 5 to 40 mm in diameter, whereas defects in the range of 15–25 mm and smaller are considered below the detectability limits of existing inspection methods. Defect types studied include missing adhesive, unintentional foreign objects that occur during the manufacturing process, damaged core, and removed core sections. An algorithm is presented to quantify the defect perimeter. The provided results demonstrate successful defect detection, with an average defect diameter error of 0.6 mm across all coupons studied in the immersion system and 1.1 mm for the portable system. The best accuracy comes from the missing adhesive coupons, with an average error of 0.3 mm. Conversely, the worst results come from the missing or damaged honeycomb coupons, with an error average of 0.7 mm, well below the standard detectability levels of 15–25 mm. Full article
(This article belongs to the Special Issue Experimental Testing, Manufacturing and Numerical Modelling of Composite and Sandwich Structures)
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Figure 1

Figure 1
<p>Representative schematic of honeycomb core material with carbon fiber facesheets.</p> Full article ">Figure 2
<p>Representative schematic of defects placed within the manufactured coupon, (<b>a</b>) foreign object debris, (<b>b</b>) crushed honeycomb, (<b>c</b>) missing adhesive, and (<b>d</b>) removed honeycomb core.</p> Full article ">Figure 3
<p>Microscope image of the adhesive film showing the associated punched holes allowing air pathways between layers (<b>a</b>) focusing on the resin adhesive sheet and (<b>b</b>) focusing on the honeycomb cell walls.</p> Full article ">Figure 4
<p>Custom immersion testing systems utilized in the present research. (<b>a</b>) Immersion scanning inspection system. (<b>b</b>) Portable (out-of-tank) inspection system.</p> Full article ">Figure 5
<p>Raster pattern and coordinate axis utilized in scanning, with the red dashed lines indicating each of the individual scans separated by an indexing of 0.1 mm and the stars representing 4 of the over 600 points separated by 0.1 mm in each line scan.</p> Full article ">Figure 6
<p>A-scans from Coupon 2, (<b>a</b>) at select locations and (<b>b</b>) the averaged A-scan.</p> Full article ">Figure 7
<p>B-scans from Coupon 2, (<b>a</b>) without upsampling and (<b>b</b>) an upsampling factor of <math display="inline"><semantics> <mrow> <mi>L</mi> <mo>=</mo> <mn>2</mn> </mrow> </semantics></math> (color bar represents the normalized signal intensity).</p> Full article ">Figure 8
<p>C-scans of Coupon 2, (<b>a</b>) prior to Gaussian filtering and (<b>b</b>) after Gaussian filtering.</p> Full article ">Figure 9
<p>C-scans of Coupons 1–3, (<b>a</b>) 7.9 mm diameter defect, (<b>b</b>) 19.0 mm diameter defect, and (<b>c</b>) 40.8 mm diameter defect.</p> Full article ">Figure 10
<p>C-scans and B-scans for coupons with the nominal 20 mm diameter defect, (<b>a</b>) C-scan for Coupon 2, missing adhesive, (<b>b</b>) C-scan for Coupon 5, Kapton FOD, (<b>c</b>) C-scan for Coupon 8, missing honeycomb, (<b>d</b>) B-scan for Coupon 2, missing adhesive, (<b>e</b>) B-scan for Coupon 5, Kapton FOD, (<b>f</b>) B-scan for Coupon 8, missing honeycomb.</p> Full article ">Figure 11
<p>C-scans and B-scans for coupons with the nominal 20 mm diameter defect, (<b>a</b>) C-scan for Coupon 11, PTFE FOD, (<b>b</b>) C-scan for Coupon 14, crushed honeycomb, (<b>c</b>) B-scan for Coupon 11, PTFE FOD, (<b>d</b>) B-scan for Coupon 14, crushed honeycomb.</p> Full article ">Figure 12
<p>C-scan comparison between coupon with a nominally 20 mm diameter missing honeycomb defect made (<b>a</b>) with film adhesive with perforations and (<b>b</b>) with roll-on paste adhesive.</p> Full article ">Figure 13
<p>C-scan comparison between Coupon 2 with the inspection performed (<b>a</b>) in the immersion tank and (<b>b</b>) in the portable scanning system.</p> Full article ">
11 pages, 2885 KiB  
Article
Oligoester Identification in the Inner Coatings of Metallic Cans by High-Pressure Liquid Chromatography–Mass Spectrometry with Cone Voltage-Induced Fragmentation
by Monika Beszterda-Buszczak and Rafał Frański
Materials 2024, 17(11), 2771; https://doi.org/10.3390/ma17112771 - 6 Jun 2024
Viewed by 1244
Abstract
The application of polyesters as food contact materials is an alternative to epoxy resin coatings, which can be a source of endocrine migrants. By using high-pressure liquid chromatography/electrospray ionization–mass spectrometry (HPLC/ESI-MS) with cone voltage-induced fragmentation in-source, a number of polyester-derived migrants were detected [...] Read more.
The application of polyesters as food contact materials is an alternative to epoxy resin coatings, which can be a source of endocrine migrants. By using high-pressure liquid chromatography/electrospray ionization–mass spectrometry (HPLC/ESI-MS) with cone voltage-induced fragmentation in-source, a number of polyester-derived migrants were detected in the extracts of inner coatings of metallic cans. The polyester-derived migrants were detected in each inner coating of fish product-containing cans (5/5) and in one inner coating of meat product-containing can (1/5). They were not detected in the inner coatings of vegetable/fruit product-containing cans (10 samples). The respective detected parent and product ions enabled differentiation between cyclic and linear compounds, as well as unambiguous identification of diol and diacid units. Most of the detected compounds, cyclic and linear, were composed of neopentyl glycol as diol and two diacid comonomers, namely isophthalic acid and hexahydrophthalic acid. The other detected oligoesters were composed of neopentyl glycol or propylene glycol and adipic acid/isophthalic acid as comonomers. The compounds containing propylene glycol as diol were found to be exclusively linear cooligoesters. On the basis of abundances of [M+Na]+ ions, the relative contents of cyclic and linear oligoesters were evaluated. Full article
(This article belongs to the Special Issue Surface Technology and Coatings Materials)
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Figure 1
<p>ESI mass spectra of linear (NPG-iPA/HHA)<sub>n</sub>-NPG oligoesters obtained for sample 17 CF (see <a href="#materials-17-02771-t001" class="html-table">Table 1</a> for ion assignments).</p> Full article ">Figure 2
<p>ESI mass spectra of cyclic (NPG-iPA/HHA)<sub>n</sub> oligoesters obtained for sample 17 CF (see <a href="#materials-17-02771-t003" class="html-table">Table 3</a> for ion assignments).</p> Full article ">Figure 2 Cont.
<p>ESI mass spectra of cyclic (NPG-iPA/HHA)<sub>n</sub> oligoesters obtained for sample 17 CF (see <a href="#materials-17-02771-t003" class="html-table">Table 3</a> for ion assignments).</p> Full article ">Figure 3
<p>ESI mass spectra of linear (NPG-HHA)<sub>2</sub>-NPG oligoester obtained for sample 17 CF and its plausible structure.</p> Full article ">Figure 4
<p>The relative content of linear and cyclic oligoesters in the analyzed samples.</p> Full article ">Figure 5
<p>The exemplary relative contributions of individual cooligoesters.</p> Full article ">Scheme 1
<p>Plausible structures, abbreviations, and masses of the diacids and diols from which the detected oligoesters are composed.</p> Full article ">
11 pages, 5270 KiB  
Article
Scalable Microwires through Thermal Drawing of Co-Extruded Liquid Metal and Thermoplastic Elastomer
by Pranjal Khakse, Falco Dangers, Rawan Elsersawy and Mohammad Abu Hasan Khondoker
Materials 2024, 17(11), 2770; https://doi.org/10.3390/ma17112770 - 6 Jun 2024
Viewed by 1277
Abstract
This article demonstrates scalable production of liquid metal (LM)-based microwires through the thermal drawing of extrudates. These extrudates were first co-extruded using a eutectic alloy of gallium and indium (EGaIn) as a core element and a thermoplastic elastomer, styrene–ethylene/butylene–styrene (SEBS), as a shell [...] Read more.
This article demonstrates scalable production of liquid metal (LM)-based microwires through the thermal drawing of extrudates. These extrudates were first co-extruded using a eutectic alloy of gallium and indium (EGaIn) as a core element and a thermoplastic elastomer, styrene–ethylene/butylene–styrene (SEBS), as a shell material. By varying the feed speed of the co-extruded materials and the drawing speed of the extrudate, it was possible to control the dimensions of the microwires, such as core diameter and shell thickness. How the extrusion temperature affects the dimensions of the microwire was also analyzed. The smallest microwire (core diameter: 52 ± 14 μm and shell thickness: 46 ± 10 μm) was produced from a drawing speed of 300.1 mm s−1 (the maximum attainable speed of the apparatus used), SEBS extrusion speed of 1.50 mm3 s−1, and LM injection rate of 5 × 105 μL s−1 at 190 °C extrusion temperature. The same extrusion condition without thermal drawing generated significantly large extrudates with a core diameter of 278 ± 26 μm and shell thickness of 430 ± 51 μm. The electrical properties of the microwires were also characterized under different degrees of stretching and wire kinking deformation which proved that these LM-based microwires change electrical resistance as they are deformed and fully self-heal once the load is removed. Finally, the sewability of these microwires was qualitatively tested by using a manual sewing machine to pattern microwires on a traditional cotton fabric. Full article
(This article belongs to the Special Issue Liquid Metals: From Fundamentals to Applications)
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<p>(<b>a</b>) 3D model of the custom extruder nozzle depicting the LM needle and nozzle assembly; (<b>b</b>) see-through model showing the co-axial needle/nozzle orientation; (<b>c</b>) entire setup showing Wellzoom and LM syringe pump on the table with winding system kept on the floor.</p> Full article ">Figure 2
<p>3D model of the system showing the three stages of the manufacturing process starting with extrusion, then thermal drawing, and finally winding spool.</p> Full article ">Figure 3
<p>Microscopic images of the cross-sections of the representative LM microwires produced with different extrusion conditions and thermal drawing speeds. LM core with SEBS shell can be seen for all microwires.</p> Full article ">Figure 4
<p>Variation in LM core diameter and SEBS shell thickness of the drawn microwires, depicting the effect of process parameters on the core–shell dimensions.</p> Full article ">Figure 5
<p>(<b>a</b>) Electrical resistance and resistivity of 10 cm long microwires produced with different drawing speeds; conductivity of a microwire drawn at 70.1 mm s<sup>−1</sup> demonstrated in the inset; (<b>b</b>) effect of different degrees of stretching of 2 cm long microwires on their electrical resistance; (<b>c</b>) 3D model of custom setup for wire kinking test; (<b>d</b>) change in resistance of 6 cm long microwires when subjected to a single kink shown for both kinking and un-kinking process from 90° (perpendicular bending) to 0° (full severed).</p> Full article ">Figure 6
<p>(<b>a</b>) Sewn microwire on traditional cotton fabric, as a proof of concept; (<b>b</b>) stitch knot from the bottom of the fabric; (<b>c</b>) stitch knot from the top side of the fabric.</p> Full article ">
15 pages, 2723 KiB  
Article
A Hydration Model to Evaluate the Properties of Cement–Quartz Powder Hybrid Concrete
by Bo Yang, Yao Liu and Xiao-Yong Wang
Materials 2024, 17(11), 2769; https://doi.org/10.3390/ma17112769 - 6 Jun 2024
Cited by 1 | Viewed by 835
Abstract
Although quartz powder is a common concrete filling material, the importance and originality of this study lies in the development of a hydration model for quartz powder–cement binary mixtures and the adoption of this model to predict the development of concrete material properties. [...] Read more.
Although quartz powder is a common concrete filling material, the importance and originality of this study lies in the development of a hydration model for quartz powder–cement binary mixtures and the adoption of this model to predict the development of concrete material properties. The purpose of this study is to use this model to promote the material design of environmentally friendly concrete and to elucidate the relationships in the development of the various properties of quartz powder concrete. The method used in this study was as follows: The parameters of the hydration model were obtained through seven days of hydration heat experiments. The hydration heat up to 28 days was also calculated, and the various properties of the concrete were predicted from the heat of hydration. The main findings of this study were as follows: (1) The ultimate hydration heat released per gram of cement for the different quartz powder substitution rates and quartz powder particle fineness was the same, at 390.145 J/g cement, as was the shape index of the hydration model at −1.003. (2) Moreover, through the model calculations, we found that, at the twenty-eighth day of the curing period for the quartz powder specimens with different quartz powder substitution amounts and different fineness, the reaction level of the cement was similar, at 0.963, as were the values of the cumulative heat of hydration, with both at 375.5 J/g cement. (3) The model showed that, in the late stage (28 days) of hydration for quartz powders of different fineness and when the substitution amount was the same, the cumulative heat of hydration over 28 days was similar. (4) The properties of concrete were evaluated using the calculated hydration heat. Overall, the predictive performance of the power and linear functions was similar, with no significant differences being found. Full article
(This article belongs to the Section Construction and Building Materials)
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<p>Test results for isothermal hydration heat. (<b>a</b>) Test results for the hydration heat of Mix 1. (<b>b</b>) Test results for the hydration heat of Mix 2. (<b>c</b>) Test results for the hydration heat of Mix 3. (<b>d</b>) Test results for the hydration heat of Mix 4.</p> Full article ">Figure 2
<p>Analysis of isothermal hydration heat. (<b>a</b>) Analysis of hydration heat of Mix 1. (<b>b</b>) Analysis of hydration heat of Mix 2. (<b>c</b>) Analysis of hydration heat of Mix 3. (<b>d</b>) Analysis of hydration heat of Mix 4.</p> Full article ">Figure 2 Cont.
<p>Analysis of isothermal hydration heat. (<b>a</b>) Analysis of hydration heat of Mix 1. (<b>b</b>) Analysis of hydration heat of Mix 2. (<b>c</b>) Analysis of hydration heat of Mix 3. (<b>d</b>) Analysis of hydration heat of Mix 4.</p> Full article ">Figure 3
<p>Calculation results of the long-term hydration heat and reaction level of cement. (<b>a</b>) Calculation results of the long-term hydration heat. (<b>b</b>) Calculation results of the long-term reaction level of cement.</p> Full article ">Figure 4
<p>Calculation results of long-term hydration heat of 1 g binder.</p> Full article ">Figure 5
<p>Regression of compressive strength. (<b>a</b>) Exponential function regression of strength. (<b>b</b>) Linear function regression of strength.</p> Full article ">Figure 6
<p>Regression of UPV. (<b>a</b>) Power function regression of UPV. (<b>b</b>) Linear function regression of UPV.</p> Full article ">Figure 7
<p>Regression of electrical resistivity. (<b>a</b>) Power function regression of electrical resistivity. (<b>b</b>) Linear function regression of electrical resistivity.</p> Full article ">
11 pages, 1628 KiB  
Article
A Study on Ammonium Chloride Dendrite Tip Kinetics: The Importance of the Solid–Liquid Density Change and Interfacial Kinetics
by Nashmi Alrasheedi, Mihaela Stefan-Kharicha, Ibrahim Sari, Mahmoud Ahmadein and Abdellah Kharicha
Materials 2024, 17(11), 2768; https://doi.org/10.3390/ma17112768 - 6 Jun 2024
Viewed by 935
Abstract
Ammonium chloride (NH4Cl) has been extensively studied as a transparent analogue for investigating the solidification of metals due to its distinctive properties and the simplicity of the experimentation. Furthermore, NH4Cl exhibits a striking resemblance in solidification behavior to the [...] Read more.
Ammonium chloride (NH4Cl) has been extensively studied as a transparent analogue for investigating the solidification of metals due to its distinctive properties and the simplicity of the experimentation. Furthermore, NH4Cl exhibits a striking resemblance in solidification behavior to the majority of binary eutectic alloy systems, rendering it a valuable model for studying phase transition phenomena. Experiments conducted on ammonium chloride are frequently employed to validate numerical models for predicting grain structures, macrosegregation, and the columnar-to-equiaxed transition (CET). This latter phenomenon arises due to differences in the velocities of columnar dendrite tips and the liquidus isosurface. However, the kinetics of dendrite tip growth, as a function of supersaturation, remains poorly understood for this commonly used alloy. The objective of this study was to utilize the available experimental data in conjunction with Ivantsov correlations to shed light on the ambiguous kinetics. The results indicate that when considering the crystal–melt density ratio, the Ivantsov solution offers a good correlation. Furthermore, incorporating a moderate interfacial kinetic coefficient enhances the correlations further. This correlation can be implemented in numerical models, which will aid in the determination of the columnar front, the columnar-to-equiaxed transition, and the equiaxed growth velocities. Full article
(This article belongs to the Section Metals and Alloys)
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<p>Growth rate of the dendrite tip as a function of supersaturation at T = 25 °C, more precisely showing the extent of occurrence of the stationary &lt;100&gt; and &lt;110&gt; forms and the non-stationary &lt;100&gt;I form with periodic splitting of the tip. Reproduced with permission from [<a href="#B34-materials-17-02768" class="html-bibr">34</a>].</p> Full article ">Figure 2
<p>Schematic of solute concentration ahead of a paraboloid of revolution growing at the speed V.</p> Full article ">Figure 3
<p>Disagreement between the measurements [<a href="#B34-materials-17-02768" class="html-bibr">34</a>] and Ivantsov solution of the dendrite tip growth rate.</p> Full article ">Figure 4
<p>Comparison between experiments [<a href="#B34-materials-17-02768" class="html-bibr">34</a>] and the predicted tip growth velocity using Equation (7) for various relative density changes for β = 0, 0.1, 0.25, 0.4, and 0.6 presented with black, yellow, blue, orange, and garnet solid line colors, respectively.</p> Full article ">Figure 5
<p>Comparison between tip velocities from experiments [<a href="#B34-materials-17-02768" class="html-bibr">34</a>] and from predictions for a constant <math display="inline"><semantics> <mrow> <mi mathvariant="sans-serif">β</mi> <mo> </mo> </mrow> </semantics></math>= 0.43 and various interfacial kinetic coefficients K.</p> Full article ">
13 pages, 4593 KiB  
Article
Effect of Carbon Fiber Paper with Thickness Gradient on Electromagnetic Shielding Performance of X-Band
by Zhi Liu, Meiping Song, Weiqi Liang, Xueping Gao and Bo Zhu
Materials 2024, 17(11), 2767; https://doi.org/10.3390/ma17112767 - 6 Jun 2024
Cited by 1 | Viewed by 1040
Abstract
Flexible paper-based materials play a crucial role in the field of flexible electromagnetic shielding due to their thinness and controllable shape. In this study, we employed the wet paper forming technique to prepare carbon fiber paper with a thickness gradient. The electromagnetic shielding [...] Read more.
Flexible paper-based materials play a crucial role in the field of flexible electromagnetic shielding due to their thinness and controllable shape. In this study, we employed the wet paper forming technique to prepare carbon fiber paper with a thickness gradient. The electromagnetic shielding performance of the carbon fiber paper varies with the ladder-like thickness distribution. Specifically, an increase in thickness gradient leads to higher reflectance of the carbon fiber paper. Within the X-band frequency range (8.2–12.4 GHz), reflectivity decreases as electromagnetic wave frequency increases, indicating enhanced penetration of electromagnetic waves into the interior of the carbon fiber paper. This enhancement is attributed to an increased fiber content per unit area resulting from a greater thickness gradient, which further enhances reflection loss and promotes internal multiple reflections and scattering effects, leading to increased absorption loss. Notably, at a 5 mm thickness, our carbon fiber paper exhibits an impressive average overall shielding performance, reaching 63.46 dB. Moreover, it exhibits notable air permeability and mechanical properties, thereby assuming a pivotal role in the realm of flexible wearable devices in the foreseeable future. Full article
(This article belongs to the Special Issue Carbon-Based Functional Nanomaterials: Preparation, Properties and Applications)
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<p>(<b>a</b>) Experimental flow chart of carbon fiber paper with thickness gradient, (<b>b</b>) carbon fiber paper with gradient thickness (The thickness showed a stepwise upward trend), and (<b>c</b>) visual picture of thickness tester testing CPT-1 to CPT-5.</p> Full article ">Figure 2
<p>SEM image and light transmission analysis of (<b>a</b>) CPT-1, (<b>b</b>) CPT-2, (<b>c</b>) CPT-3, and (<b>d</b>) CPT-5 step-thickness carbon fiber paper.</p> Full article ">Figure 3
<p>Surface resistance of carbon fiber paper. (To facilitate the distinction, the color of CPT-1 is black, the color of CPT-2 is red, the color of CPT-3 is blue, and the color of CPT-5 is green).</p> Full article ">Figure 4
<p>Carbon fiber paper in the X-band (<b>a</b>) reflection coefficient <span class="html-italic">R</span>, (<b>b</b>) absorption coefficient <span class="html-italic">A</span>, (<b>c</b>) reflection loss <span class="html-italic">SE</span><sub>R</sub>, (<b>d</b>) absorption loss <span class="html-italic">SE</span><sub>A</sub>, (<b>e</b>) overall shielding performance <span class="html-italic">SE</span><sub>T</sub>, and (<b>f</b>) average EMI <span class="html-italic">SE</span> of the carbon fiber paper material (Arrows show an overall upward trend).</p> Full article ">Figure 5
<p>3D plot of electromagnetic parameters (<b>a</b>) <span class="html-italic">R</span>, (<b>b</b>) <span class="html-italic">A</span>, (<b>c</b>) <span class="html-italic">SE</span><sub>R</sub>, (<b>d</b>) <span class="html-italic">SE</span><sub>A</sub>, and (<b>e</b>) <span class="html-italic">SE</span><sub>T</sub> in relation to thickness at X-band.</p> Full article ">Figure 6
<p>(<b>a</b>) Voltage–current change curves, (<b>b</b>) saturation temperature of carbon fiber paper with different current thickness gradients, and (<b>c</b>) CPT-1 carbon fiber paper under different current temperature change curves.</p> Full article ">Figure 7
<p>CPT-5 is (<b>a</b>) wound on the surface of a cylindrical barrel and (<b>b</b>) placed on the stamen; (<b>c</b>) Schematic diagram of Tesla coil; (<b>d</b>) The Tesla coil is lit in space. (<b>e</b>) CPT-1 blocks electromagnetic wave propagation and the small bulb is extinguished.</p> Full article ">
2 pages, 533 KiB  
Correction
Correction: Rajabi et al. Solvent-Free Preparation of 1,8-Dioxo-Octahydroxanthenes Employing Iron Oxide Nanomaterials. Materials 2019, 12, 2386
by Fatemeh Rajabi, Mohammad Abdollahi, Elham Sadat Diarjani, Mikhail G. Osmolowsky, Olga M. Osmolovskaya, Paulette Gómez-López, Alain R. Puente-Santiago and Rafael Luque
Materials 2024, 17(11), 2766; https://doi.org/10.3390/ma17112766 - 6 Jun 2024
Viewed by 584
Abstract
It has been brought to the attention of the Editorial Office that Figure 1 in the original publication [...] Full article
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<p>Transmission electron microscopy image of spent FeNP@SBA-15 (after 10 runs).</p> Full article ">
14 pages, 5357 KiB  
Article
Metal 3D-Printed Bioinspired Lattice Elevator Braking Pads for Enhanced Dynamic Friction Performance
by Nikolaos Kladovasilakis, Eleftheria Maria Pechlivani, Ioanna K. Sfampa, Konstantinos Tsongas, Apostolos Korlos, Constantine David and Dimitrios Tzovaras
Materials 2024, 17(11), 2765; https://doi.org/10.3390/ma17112765 - 5 Jun 2024
Cited by 3 | Viewed by 1200
Abstract
The elevator industry is constantly expanding creating an increased demand for the integration of high technological tools to increase elevator efficiency and safety. Towards this direction, Additive Manufacturing (AM), and especially metal AM, is one of the technologies that could offer numerous competitive [...] Read more.
The elevator industry is constantly expanding creating an increased demand for the integration of high technological tools to increase elevator efficiency and safety. Towards this direction, Additive Manufacturing (AM), and especially metal AM, is one of the technologies that could offer numerous competitive advantages in the production of industrial parts, such as integration of complex geometry, high manufacturability of high-strength metal alloys, etc. In this context, the present study has 3D designed, 3D printing manufactured, and evaluated novel bioinspired structures for elevator safety gear friction pads with the aim of enhancing their dynamic friction performance and eliminating the undesired behavior properties observed in conventional pads. Four different friction pads with embedded bioinspired surface lattice structures were formed on the template of the friction surface of the conventional pads and 3D printed by the Selective Laser Melting (SLM) process utilizing tool steel H13 powder as feedstock material. Each safety gear friction pad underwent tribological tests to evaluate its dynamic coefficient of friction (CoF). The results indicated that pads with a high contact surface area, such as those with car-tire-like and extended honeycomb structures, exhibit high CoF of 0.549 and 0.459, respectively. Based on the acquired CoFs, Finite Element Models (FEM) were developed to access the performance of braking pads under realistic operation conditions, highlighting the lower stress concentration for the aforementioned designs. The 3D-printed safety gear friction pads were assembled in an existing emergency progressive safety gear system of KLEEMANN Group, providing sufficient functionality. Full article
(This article belongs to the Special Issue Metal Additive Manufacturing: Design, Performance, and Applications)
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<p>Image of an indicative existing progressive emergency braking system along with its position on the elevator’s system.</p> Full article ">Figure 2
<p>Flowchart of the current study.</p> Full article ">Figure 3
<p>Isometric, front, and detailed view of the designed surface architected materials of (unit: mm): (<b>a</b>) Extended honeycomb; (<b>b</b>) Honeycomb; (<b>c</b>) Speckled honeycomb; (<b>d</b>) Car-tire-like configurations.</p> Full article ">Figure 4
<p>Fixation and loading conditions on the commercial friction pad for the developed FEMs.</p> Full article ">Figure 5
<p>(<b>a</b>) The developed 3D-printed friction pads; (<b>b</b>) The friction pads inside the building chamber; (<b>c</b>) Indicative images of the assembly between the developed friction pads and the elevator safety gear.</p> Full article ">Figure 6
<p>Surface roughness contour and roughness profile of an indicative braking surface of the 3D-printed pads.</p> Full article ">Figure 7
<p>Indicative images of the (<b>a</b>) car-tire-like and (<b>b</b>) honeycomb friction pads during the pin-on-disc tribological tests.</p> Full article ">Figure 8
<p>Tribological results of CoF to distance for pad’s structures of: (<b>a</b>) Honeycomb; (<b>b</b>) Speckled honeycomb; (<b>c</b>) Extended honeycomb, and (<b>d</b>) Car-tire-like.</p> Full article ">Figure 9
<p>Equivalent von Mises contours for pad structures of: (<b>a</b>) Standard (<b>b</b>) Honeycomb; (<b>c</b>) Speckled honeycomb; (<b>d</b>) Extended honeycomb, and (<b>e</b>) Car-tire-like.</p> Full article ">
16 pages, 5345 KiB  
Article
Investigation of Particle Rotation Characteristics and Compaction Quality Control of Asphalt Pavement Using the Discrete Element Method
by Zhi Zhang, Hancheng Dan, Hongyu Shan and Songlin Li
Materials 2024, 17(11), 2764; https://doi.org/10.3390/ma17112764 - 5 Jun 2024
Viewed by 960
Abstract
The compaction of asphalt pavement is a crucial step to ensure its service life. Although intelligent compaction technology can monitor compaction quality in real time, its application to individual asphalt surface courses still faces limitations. Therefore, it is necessary to study the compaction [...] Read more.
The compaction of asphalt pavement is a crucial step to ensure its service life. Although intelligent compaction technology can monitor compaction quality in real time, its application to individual asphalt surface courses still faces limitations. Therefore, it is necessary to study the compaction mechanism of asphalt pavements from the particle level to optimize intelligent compaction technology. This study constructed an asphalt pavement compaction model using the Discrete Element Method (DEM). First, the changes in pavement smoothness during the compaction process were analyzed. Second, the changes in the angular velocity of the mixture and the triaxial angular velocity (TAV) of the mortar, aggregates, and mixture during vibratory compaction were examined. Finally, the correlations between the TAV amplitude and the coordination number (CN) amplitude with the compaction degree of the mixture were investigated. This study found that vibratory compaction can significantly reduce asymmetric wave deformation, improving pavement smoothness. The mixture primarily rotates in the vertical plane during the first six passes of vibratory compaction and within the horizontal plane during the seventh pass. Additionally, TAV reveals the three-dimensional dynamic rotation characteristics of the particles, and the linear relationship between its amplitude and the pavement compaction degree aids in controlling the compaction quality of asphalt pavements. Finally, the linear relationship between CN amplitude and pavement compaction degree can predict the stability of the aggregate structure. This study significantly enhances quality control in pavement compaction and advances intelligent compaction technology development. Full article
(This article belongs to the Section Construction and Building Materials)
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<p>Asphalt pavement compaction model: (<b>a</b>) mortar, (<b>b</b>) aggregate, (<b>c</b>) loose pavement, (<b>d</b>) simplified drum, (<b>e</b>) pavement before precompaction of the paver, and (<b>f</b>) pavement after precompaction of the paver.</p> Full article ">Figure 2
<p>The curve of normal contact force vs. overlap for the contact model: (<b>a</b>) nonlinear and (<b>b</b>) linear.</p> Full article ">Figure 3
<p>The schematic diagram for the selection of particle contact models.</p> Full article ">Figure 4
<p>The vibration compaction force of the drum.</p> Full article ">Figure 5
<p>The change in compaction degree with different compaction passes.</p> Full article ">Figure 6
<p>The cloud diagram of the z-axis positions of particles under different compaction passes: (<b>a</b>) static compaction and (<b>b</b>) vibratory compaction.</p> Full article ">Figure 7
<p>The changes in angular velocity over time during compaction: (<b>a</b>) mortar, (<b>b</b>) aggregate, and (<b>c</b>) mixture.</p> Full article ">Figure 8
<p>The changes in TAV over compaction time: (<b>a</b>) mortar, (<b>b</b>) aggregate, and (<b>c</b>) mixture.</p> Full article ">Figure 9
<p>The change in angular velocity amplitude with vibratory compaction passes: (<b>a</b>) x-axis, (<b>b</b>) y-axis, and (<b>c</b>) z-axis.</p> Full article ">Figure 10
<p>The changes in TAV amplitude with vibratory compaction passes: (<b>a</b>) mortar, (<b>b</b>) aggregate, and (<b>c</b>) mixture.</p> Full article ">Figure 11
<p>The correlation between TAV amplitude and compaction degree of the mixture: (<b>a</b>) mixture, (<b>b</b>) aggregate, and (<b>c</b>) mortar.</p> Full article ">Figure 12
<p>The changes in particle CN with compaction time: (<b>a</b>) mixture and (<b>b</b>) aggregate.</p> Full article ">Figure 13
<p>The correlation between CN amplitude and compaction degree of the mixture: (<b>a</b>) mixture and (<b>b</b>) aggregate.</p> Full article ">
16 pages, 4302 KiB  
Article
CaAl-Layered Double Hydroxides-Modified Biochar Composites Mitigate the Toxic Effects of Cu and Pb in Soil on Pea Seedlings
by Yuanzheng Wang, Yuhao Cai, Yuxuan Wu, Caiya Yan, Zhi Dang and Hua Yin
Materials 2024, 17(11), 2763; https://doi.org/10.3390/ma17112763 - 5 Jun 2024
Viewed by 973
Abstract
Compound contamination of soil with heavy metals copper (Cu) and lead (Pb) triggered by mining development has become a serious problem. To solve this problem, in this paper, corncob kernel, which is widely available and inexpensive, was used as the raw material of [...] Read more.
Compound contamination of soil with heavy metals copper (Cu) and lead (Pb) triggered by mining development has become a serious problem. To solve this problem, in this paper, corncob kernel, which is widely available and inexpensive, was used as the raw material of biochar and modified by loading CaAl-layered double hydroxides to synthesize biochar-loaded CaAl-layered double hydroxide composites (CaAl-LDH/BC). After soil remediation experiments, either BC or CaAl-LDH/BC can increase soil pH, and the available phosphorus content and available potassium content in soil. Compared with BC, CaAl-LDH/BC significantly reduced the available content of Cu and Pb in the active state (diethylenetriaminepentaacetic acid extractable state) in the soil, and the passivation rate of Cu and Pb by a 2% dosage of CaAl-LDH/BC reached 47.85% and 37.9%, respectively. CaAl-LDH/BC can significantly enhance the relative abundance of beneficial microorganisms such as Actinobacteriota, Gemmatimonadota, and Luteimonas in the soil, which can help to enhance the tolerance and reduce the enrichment ability of plants to heavy metals. In addition, it was demonstrated by pea seedling (Pisum sativum L.) growing experiments that CaAl-LDH/BC increased plant fresh weight, root length, plant height, catalase (CAT) activity, and protein content, which promoted the growth of the plant. Compared with BC, CaAl-LDH/BC significantly reduced the Cu and Pb contents in pea seedlings, in which the Cu and Pb contents in pea seedlings were reduced from 31.97 mg/kg and 74.40 mg/kg to 2.92 mg/kg and 6.67 mg/kg, respectively, after a 2% dosage of CaAl-LDH/BC, which was a reduction of 90.84% and 91.03%, respectively. In conclusion, compared with BC, CaAl-LDH/BC improved soil fertility and thus the plant growth environment, and also more effectively reduced the mobility of heavy metals Cu and Pb in the soil to reduce the enrichment of Cu and Pb by plants. Full article
(This article belongs to the Topic Advances in Biomass Conversion)
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<p>XRD spectra (<b>a</b>) and FTIR spectra (<b>b</b>) of CaAl-LDH/BC and BC; SEM of BC (<b>c</b>) and CaAl-LDH/BC (<b>d</b>). (LDH/BC in the figure implies CaAl-LDH/BC).</p> Full article ">Figure 2
<p>Effect of BC and CaAl-LDH/BC on Cu (<b>a</b>) and Pb (<b>b</b>) effective state concentrations. (The a, b, c, d, e, and f near the error bars represent significant differences according to the Student’s <span class="html-italic">t</span>-test [<span class="html-italic">p</span> &lt; 0.5]).</p> Full article ">Figure 3
<p>Effects of BC 2 and LB 2 on microbial communities at the gate level.</p> Full article ">Figure 4
<p>Effects of BC 2 and LB 2 on microbial communities at the genus level.</p> Full article ">Figure 5
<p>Average root length (<b>a</b>), average plant height (<b>b</b>), and average fresh weight (<b>c</b>) of pea seedlings in blank and treated soils. (The a, b, and c near the error bars represent significant differences according to the Student’s <span class="html-italic">t</span>-test [<span class="html-italic">p</span> &lt; 0.5]).</p> Full article ">Figure 6
<p>CAT activity (<b>a</b>) and protein content (<b>b</b>) of pea seedlings in soil. (The a, b, c, d, and e near the error bars represent significant differences according to the Student’s <span class="html-italic">t</span>-test [<span class="html-italic">p</span> &lt; 0.5]).</p> Full article ">Figure 7
<p>Cu content (<b>a</b>) and Pb content (<b>b</b>) of pea seedlings in treated soils. (The a, b, c, d and e near the error bars represent significant differences according to the Student’s <span class="html-italic">t</span>-test [<span class="html-italic">p</span> &lt; 0.5]).</p> Full article ">
26 pages, 10958 KiB  
Article
Micro-Inclusion Engineering via Sc Incompatibility for Luminescence and Photoconversion Control in Ce3+-Doped Tb3Al5−xScxO12 Garnet
by Karol Bartosiewicz, Robert Tomala, Damian Szymański, Benedetta Albini, Justyna Zeler, Masao Yoshino, Takahiko Horiai, Paweł Socha, Shunsuke Kurosawa, Kei Kamada, Pietro Galinetto, Eugeniusz Zych and Akira Yoshikawa
Materials 2024, 17(11), 2762; https://doi.org/10.3390/ma17112762 - 5 Jun 2024
Viewed by 1168
Abstract
Aluminum garnets display exceptional adaptability in incorporating mismatching elements, thereby facilitating the synthesis of novel materials with tailored properties. This study explored Ce3+-doped Tb3Al5−xScxO12 crystals (where x ranges from 0.5 to 3.0), revealing a [...] Read more.
Aluminum garnets display exceptional adaptability in incorporating mismatching elements, thereby facilitating the synthesis of novel materials with tailored properties. This study explored Ce3+-doped Tb3Al5−xScxO12 crystals (where x ranges from 0.5 to 3.0), revealing a novel approach to control luminescence and photoconversion through atomic size mismatch engineering. Raman spectroscopy confirmed the coexistence of garnet and perovskite phases, with Sc substitution significantly influencing the garnet lattice and induced A1g mode softening up to Sc concentration x = 2.0. The Sc atoms controlled sub-eutectic inclusion formation, creating efficient light scattering centers and unveiling a compositional threshold for octahedral site saturation. This modulation enabled the control of energy transfer dynamics between Ce3+ and Tb3+ ions, enhancing luminescence and mitigating quenching. The Sc admixing process regulated luminous efficacy (LE), color rendering index (CRI), and correlated color temperature (CCT), with adjustments in CRI from 68 to 84 and CCT from 3545 K to 12,958 K. The Ce3+-doped Tb3Al5−xScxO12 crystal (where x = 2.0) achieved the highest LE of 114.6 lm/W and emitted light at a CCT of 4942 K, similar to daylight white. This approach enables the design and development of functional materials with tailored optical properties applicable to lighting technology, persistent phosphors, scintillators, and storage phosphors. Full article
(This article belongs to the Special Issue Advanced Luminescent Materials: Synthesis, Properties and Applications)
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Graphical abstract
Full article ">Figure 1
<p>As-grown rods and polished radial plates of Tb<sub>2.85</sub>Ce<sub>0.15</sub>Al<sub>5−x</sub>Sc<sub>x</sub>O<sub>12</sub> crystals with increasing Sc<sup>3+</sup> ion concentration.</p> Full article ">Figure 2
<p>Theoretical [Tb<sub>3</sub>(Al,Sc)<sub>5</sub>O<sub>12</sub>—#PDF 53-0273; TbScO<sub>3</sub>—#PDF27-0599; TbAlO<sub>3</sub>—#PDF 24-127) and experimental PXRD patterns of Ce<sup>3+</sup>-doped Tb<sub>3</sub>Al<sub>5−x</sub>Sc<sub>x</sub>O<sub>12</sub> crystals, where x = 0.5, 1.0, 1.5, 2.0 and 3.0.</p> Full article ">Figure 3
<p>SEM images and corresponding EDS elemental distribution maps of terbium (Tb, yellow), scandium (Sc, cyan), aluminum (Al, green), and oxygen (O, red) of Ce<sup>3+</sup>-doped Tb<sub>3</sub>Al<sub>5−x</sub>Sc<sub>x</sub>O<sub>12</sub> crystals, where x = 0.5, 1.0, 1.5, 2.0, and 3.0.</p> Full article ">Figure 4
<p>EDS line scanning profiles of terbium (Tb, yellow), scandium (Sc, cyan), aluminum (Al, green), and oxygen (O, red) recorded along a diameter of Ce<sup>3+</sup>-doped Tb<sub>3</sub>Al<sub>5−x</sub>Sc<sub>x</sub>O<sub>12</sub> crystals, where x = 0.5, 1.0, 1.5, 2.0, and 3.0.</p> Full article ">Figure 5
<p>(<b>a</b>) Raman spectra acquired at an excitation wavelength of 638 nm probing the secondary phase inclusions present in the Ce<sup>3+</sup>-doped Tb<sub>3</sub>Al<sub>5−x</sub>Sc<sub>x</sub>O<sub>12</sub> crystals, where x = 0.5 and 3.0 (300 K); (<b>b</b>) Raman spectra acquired at an excitation wavelength of 785 nm, probing the garnet matrix of Ce<sup>3+</sup>-doped Tb<sub>3</sub>Al<sub>5−x</sub>Sc<sub>x</sub>O<sub>12</sub> crystals, where x = 0.5, 1.0, 1.5, 2.0, and 3.0; (<b>c</b>) the <span class="html-italic">A<sub>1g</sub></span> mode peak energy position at 770 cm<sup>−1</sup> for Tb<sub>2.85</sub>Ce<sub>0.15</sub>Al<sub>4.5</sub>Sc<sub>0.5</sub>O<sub>12</sub> as a function of Sc<sup>3+</sup> ion concentration.</p> Full article ">Figure 6
<p>Evolution of TL glow curves in Ce<sup>3+</sup>-doped Tb<sub>3</sub>Al<sub>5−x</sub>Sc<sub>x</sub>O<sub>12</sub> crystals, where x = 0.5, 1.0, 1.5, 2.0, and 3.0.</p> Full article ">Figure 7
<p>Unpolarized optical absorption spectra of Ce<sup>3+</sup>-doped Tb<sub>3</sub>Al<sub>5−x</sub>Sc<sub>x</sub>O<sub>12</sub>, where x = 0.5, 1.0, 1.5, 2.0, and 3.0 (300 K). The absorption spectra exhibit saturation below 300 nm due to the combined effects of the high Tb<sup>3+</sup> concentration (95.5% dodecahedral site occupancy), spin-allowed <span class="html-italic">4f</span> → <span class="html-italic">5d</span> transitions, and local environmental variations within the multiphase structure. The intense background for the Ce<sup>3+</sup>-doped Tb<sub>3</sub>Al<sub>5−x</sub>Sc<sub>x</sub>O<sub>12</sub> crystal where x = 3.0 arises from increased light scattering caused by reduced crystal transparency.</p> Full article ">Figure 8
<p>RT excitation spectra of Ce<sup>3+</sup>-doped Tb<sub>3</sub>Al<sub>5−x</sub>Sc<sub>x</sub>O<sub>12</sub> crystals, where x = 0.5, 1.0, 1.5, 2.0, and 3.0 recorded at 550 nm corresponding to the <span class="html-italic">5d<sub>1</sub></span> → <span class="html-italic">4f</span> transition of Ce<sup>3+</sup> ions (300 K).</p> Full article ">Figure 9
<p>Temperature-dependent photoluminescence (<b>a</b>–<b>e</b>) emission spectra (λ<sub>exc</sub> = 455 nm) and (<b>f</b>) emission spectra integrals between 480 and 750 nm of Ce<sup>3+</sup>-doped Tb<sub>3</sub>Al<sub>5−x</sub>Sc<sub>x</sub>O<sub>12</sub> crystals, as measured at temperatures ranging from 83 K to 683 K, exhibiting the impact of increasing Sc<sup>3+</sup> ion concentration.</p> Full article ">Figure 10
<p>(<b>a</b>) Selected decay curves of the emission at 560 nm (λ<sub>exc</sub> = 455 nm) for Ce<sup>3+</sup>-doped Tb<sub>3</sub>Al<sub>5−x</sub>Sc<sub>x</sub>O<sub>12</sub> crystals, where x = 0.5, 1.5, and 3.0 recorded at 83 K; (<b>b</b>) dependence of photoluminescence decay times on temperature for emission at 560 nm (λ<sub>exc</sub> = 455 nm) in Ce<sup>3+</sup>-doped Tb<sub>3</sub>Al<sub>5−x</sub>Sc<sub>x</sub>O<sub>12</sub> with increasing Sc<sup>3+</sup> ion concentration.</p> Full article ">Figure 11
<p>The photoconversion spectra of Ce<sup>3+</sup>-doped Tb<sub>3</sub>Al<sub>5−x</sub>Sc<sub>x</sub>O<sub>12</sub> crystals delineate the impact of varying Sc<sup>3+</sup> ion concentrations under (<b>a</b>) 445 nm laser diode and (<b>b</b>) 455 nm light-emitting diode excitations; (<b>c</b>) representation of observed emission spectra for LED and LD plotted on the CIE 1931 chromaticity diagram.</p> Full article ">Figure 12
<p>Radioluminescence spectra of Ce<sup>3+</sup>-doped Tb<sub>3</sub>Al<sub>5−x</sub>Sc<sub>x</sub>O<sub>12</sub> crystals, where x = 0.5, 1.0, 1.5, 2.0, and 3.0.</p> Full article ">
13 pages, 2316 KiB  
Article
Long-Term Thermal Stabilization of Poly(Lactic Acid)
by Jannik Hallstein, Elke Metzsch-Zilligen and Rudolf Pfaendner
Materials 2024, 17(11), 2761; https://doi.org/10.3390/ma17112761 - 5 Jun 2024
Viewed by 1230
Abstract
To use polylactic acid in demanding technical applications, sufficient long-term thermal stability is required. In this work, the thermal aging of polylactic acid (PLA) in the solid phase at 100 °C and 150 °C is investigated. PLA has only limited aging stability without [...] Read more.
To use polylactic acid in demanding technical applications, sufficient long-term thermal stability is required. In this work, the thermal aging of polylactic acid (PLA) in the solid phase at 100 °C and 150 °C is investigated. PLA has only limited aging stability without the addition of stabilizers. Therefore, the degradation mechanism in thermal aging was subsequently investigated in more detail to identify a suitable stabilization strategy. Investigations using nuclear magnetic resonance spectroscopy showed that, contrary to expectations, even under thermal aging conditions, hydrolytic degradation rather than oxidative degradation is the primary degradation mechanism. This was further confirmed by the investigation of suitable stabilizers. While the addition of phenols, phosphites and thioethers as antioxidants leads only to a limited improvement in aging stability, the addition of an additive composition to provide hydrolytic stabilization results in extended durability. Efficient compositions consist of an aziridine-based hydrolysis inhibitor and a hydrotalcite co-stabilizer. At an aging temperature of 100 °C, the time until significant polymer chain degradation occurs is extended from approx. 500 h for unstabilized polylactic acid to over 2000 h for stabilized polylactic acid. Full article
(This article belongs to the Section Polymeric Materials)
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<p>Chemical structures of used additives.</p> Full article ">Figure 2
<p>Melt volume rate of PLA (black line) during thermal aging at 150 °C.</p> Full article ">Figure 3
<p>Molecular weight distribution of PLA over the course of the thermal aging at 150 °C.</p> Full article ">Figure 4
<p>Polymerization reaction of PLA [<a href="#B29-materials-17-02761" class="html-bibr">29</a>].</p> Full article ">Figure 5
<p><sup>1</sup>H-NMR of the differently aged samples in the range from 4.2 to 5.5 ppm. Changes in the spectrum occur at a chemical shift of 4.4 ppm (red circle).</p> Full article ">Figure 6
<p>Oxidative degradation of PLA (according to [<a href="#B13-materials-17-02761" class="html-bibr">13</a>,<a href="#B39-materials-17-02761" class="html-bibr">39</a>]).</p> Full article ">Figure 7
<p>Mass (black line/squares) and percentage mass loss (green line/dots) of 60 g PLA granules during 150 °C aging.</p> Full article ">Figure 8
<p>Melt volume rate over aging time at 100 °C for PLA with different stabilizers.</p> Full article ">Figure 9
<p>Melt volume rate over aging time at 150 °C for PLA with a hydrolysis stabilizer.</p> Full article ">
14 pages, 5705 KiB  
Article
Effect of Secondary Phase on Passivation Layer of Super Duplex Stainless Steel UNS S 32750: Advanced Safety of Li-Ion Battery Case Materials
by Byung-Hyun Shin, Seongjun Kim, Jinyong Park, Jung-Woo Ok, Dohyung Kim and Jang-Hee Yoon
Materials 2024, 17(11), 2760; https://doi.org/10.3390/ma17112760 - 5 Jun 2024
Cited by 2 | Viewed by 1129
Abstract
Aluminum, traditionally the primary material for battery casings, is increasingly being replaced by UNS S 30400 for enhanced safety. UNS S 30400 offers superior strength and corrosion resistance compared to aluminum; however, it undergoes a phase transformation owing to stress during processing and [...] Read more.
Aluminum, traditionally the primary material for battery casings, is increasingly being replaced by UNS S 30400 for enhanced safety. UNS S 30400 offers superior strength and corrosion resistance compared to aluminum; however, it undergoes a phase transformation owing to stress during processing and a lower high-temperature strength. Duplex stainless steel UNS S 32750, consisting of both austenite and ferrite phases, exhibits excellent strength and corrosion resistance. However, it also precipitates secondary phases at high temperatures, which are known to form through the segregation of Cr and Mo. Various studies have investigated the corrosion resistance of UNS S 32750; however, discrepancies exist regarding the formation and thickness of the passivation layer. This study analyzed the oxygen layer on the surface of UNS S 32750 after secondary-phase precipitation. The microstructure, volume fraction, chemical composition, and depth of O after the precipitation of the secondary phases in UNS S 32750 was examined using FE-SEM, EDS, EPMA and XRD, and the surface chemical composition and passivation layer thickness were analyzed using electron probe microanalysis and glow-discharge spectroscopy. This study demonstrated the segregation of alloy elements and a reduction in the passivation-layer thickness after precipitation from 25 μm to 20 μm. The findings of the analysis aid in elucidating the impact of secondary-phase precipitation on the passivation layer. Full article
(This article belongs to the Special Issue Quality, Microstructure and Properties of Metal Alloys (Second Volume))
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<p>Schematic diagram of heat-treatment conditions for application on a Li-ion battery case of super duplex stainless steel UNS S 32750.</p> Full article ">Figure 2
<p>Microstructure image of super duplex stainless steel UNS S 32750: (<b>a</b>) cast and (<b>b</b>) solution annealed at 1100 °C (γ: austenite, and δ: ferrite), (<b>c</b>) Phase-IQ after solution annealing at 1100 °C, (<b>d</b>) IPF-IQ image after solution annealing at 1100 °C, (<b>e</b>) grain size and area fraction after solution annealing at 1100 °C, and (<b>f</b>) IPF color palette.</p> Full article ">Figure 3
<p>Volume fractions of austenite and ferrite for casting and solution-annealing manufacturing processes of super duplex stainless steel UNS S 32750.</p> Full article ">Figure 4
<p>Microstructure image after heat treatment at 700 °C of super duplex stainless steel UNS S 32750: (<b>a</b>) magnification ×200, (<b>b</b>) magnification ×5000 (yellow arrow: secondary phase), (<b>c</b>) Phase-IQ (red: austenite, green: ferrite) after solution annealing at 1100 °C (yellow circle: secondary phase), (<b>d</b>) IPF-IQ image after solution annealing at 1100 °C (yellow circle: secondary phase), (<b>e</b>) grain size and area fraction, and (<b>f</b>) IPF color palette.</p> Full article ">Figure 4 Cont.
<p>Microstructure image after heat treatment at 700 °C of super duplex stainless steel UNS S 32750: (<b>a</b>) magnification ×200, (<b>b</b>) magnification ×5000 (yellow arrow: secondary phase), (<b>c</b>) Phase-IQ (red: austenite, green: ferrite) after solution annealing at 1100 °C (yellow circle: secondary phase), (<b>d</b>) IPF-IQ image after solution annealing at 1100 °C (yellow circle: secondary phase), (<b>e</b>) grain size and area fraction, and (<b>f</b>) IPF color palette.</p> Full article ">Figure 5
<p>Intensity (counts) vs. 2θ (degrees) curve; X-ray diffraction pattern after heat treatment at 700 °C and 1100 °C of super duplex stainless steel UNS S 32750.</p> Full article ">Figure 6
<p>Mapping image of chemical composition by electron-probe microanalysis after heat treatment at 700 °C of super duplex stainless steel UNS S 32750: (<b>a</b>) Cr, (<b>b</b>), Mo, (<b>c</b>), Ni, (<b>d</b>) Mn, and (<b>e</b>) Fe.</p> Full article ">Figure 7
<p>Potential (V) vs. current density curve (A/cm<sup>2</sup>); potentiodynamic polarization curve of super duplex stainless steel UNS S 32750 in 3.5 wt% Nacl electrolyte solution.</p> Full article ">Figure 8
<p>Intensity (counts) vs. thickness (nm) curve; glow-discharge spectrometer (GDS) results with or without secondary phase of super duplex stainless steel UNS S 32750: (<b>a</b>) GDS results of O, (<b>b</b>) GDS results of Cr, and (<b>c</b>) GDS results of Fe (black and red arrows, passivation layer thickness).</p> Full article ">Figure 9
<p>Schematic of passivation-layer formation with or without secondary phase of super duplex stainless steel UNS S 32750: (<b>a</b>) austenite growth and decrease in passivation layer (black arrow, austenite growth direction), (<b>b</b>) precipitation of secondary phase and decrease in partial passivation layer thickness, (<b>c</b>) growth of Sigma and decreased passivation-layer thickness, and (<b>d</b>) precipitation Chi phase and lower passivation-layer thickness.</p> Full article ">Figure 10
<p>Cross-section image after potentiodynamic polarization curve of super duplex stainless steel UNS S 32750 in 3.5 wt% NaCl electrolyte solution (yellow arrow: pitting morphology): (<b>a</b>) heat treatment at 700 °C and (<b>b</b>) heat treatment at 1100 °C.</p> Full article ">
14 pages, 2287 KiB  
Article
Effect of Secondary Foaming on the Structural Properties of Polyurethane Polishing Pad
by Minxuan Chen, Zhenlin Jiang, Min Zhu, Baoxiu Wang, Jiapeng Chen and Wenjun Wang
Materials 2024, 17(11), 2759; https://doi.org/10.3390/ma17112759 - 5 Jun 2024
Cited by 1 | Viewed by 992
Abstract
Polyurethane polishing pads are important in chemical mechanical polishing (CMP). Thus, understanding how to decrease the density but increase the porosity is a crucial aspect of improving the efficiency of a polyurethane polishing pad. According to the principle of gas generation by thermal [...] Read more.
Polyurethane polishing pads are important in chemical mechanical polishing (CMP). Thus, understanding how to decrease the density but increase the porosity is a crucial aspect of improving the efficiency of a polyurethane polishing pad. According to the principle of gas generation by thermal decomposition of sodium bicarbonate and ammonium bicarbonate, polyurethane polishing pad was prepared by a secondary foaming method. The influence of adding such an inorganic foaming agent as an auxiliary foaming agent on the structure, physical properties, and mechanical properties of polyurethane polishing pads was discussed. The results showed that compared with the polyurethane polishing pad without an inorganic foaming agent, the open-pore structure increased, the density decreased, and the porosity and water absorption increased significantly. The highest porosity and material removal rate (MRR) with sodium bicarbonate added was 3.3% higher than those without sodium bicarbonate and 33.8% higher than those without sodium bicarbonate. In addition, the highest porosity and MRR with ammonium bicarbonate were 7.2% higher and 47.8% higher than those without ammonium bicarbonate. Therefore, it was finally concluded that the optimum amount of sodium bicarbonate to be added was 3 wt%, and the optimum amount of ammonium bicarbonate to be added was 1 wt%. Full article
(This article belongs to the Section Polymeric Materials)
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<p>Thermal decomposition diagrams of NaHCO<sub>3</sub> and NH<sub>4</sub>HCO<sub>3</sub>: TG−DTG curve (<b>a</b>) and DSC curve (<b>b</b>) of NaHCO<sub>3</sub>, and TG−DTG curve (<b>c</b>) and DSC curve (<b>d</b>) of NH<sub>4</sub>HCO<sub>3</sub>.</p> Full article ">Figure 2
<p>FT−IR spectrum of polyurethane foam with added NaHCO<sub>3</sub> and NH<sub>4</sub>HCO<sub>3</sub>.</p> Full article ">Figure 3
<p>SEM images of foamed samples with added NaHCO<sub>3</sub> ((<b>a</b>) 1 wt%, (<b>b</b>) 2 wt%, (<b>c</b>) 3 wt%, (<b>d</b>) 5 wt%).</p> Full article ">Figure 4
<p>SEM images of foamed samples with added NH<sub>4</sub>CO<sub>3</sub> ((<b>a</b>) 0.5 wt%, (<b>b</b>) 1 wt%, (<b>c</b>) 2 wt%, (<b>d</b>) 3 wt%, (<b>e</b>) 5 wt%).</p> Full article ">Figure 5
<p>Aperture distribution curves of blowing agents with different additive amounts: (<b>a</b>) NaHCO<sub>3</sub> and (<b>b</b>) NH<sub>4</sub>CO<sub>3</sub>.</p> Full article ">Figure 6
<p>Physical properties of blowing agents with different additions (<b>a</b>) density volume water absorption of samples with added NaHCO<sub>3</sub>, (<b>b</b>) density volume water absorption of samples with added NH<sub>4</sub>CO<sub>3</sub>, and (<b>c</b>) porosity.</p> Full article ">Figure 7
<p>Mechanical properties of blowing agents with different additions (<b>a</b>) hardness of samples with added NaHCO<sub>3</sub>, (<b>b</b>) hardness of samples with added NH<sub>4</sub>CO<sub>3</sub>, (<b>c</b>) compressive strength curve of samples with added NaHCO<sub>3</sub>, and (<b>d</b>) compressive strength curve of samples with added NH<sub>4</sub>CO<sub>3</sub>, (<b>e</b>) Young’s modulus and Poisson’s ratio with the addition of sodium bicarbonate, (<b>f</b>) Young’s modulus and Poisson’s ratio with added ammonium bicarbonate.</p> Full article ">Figure 8
<p>Material removal rate of polyurethane polishing pad.</p> Full article ">
13 pages, 8022 KiB  
Communication
Hydrothermal Growth and Orientation of LaFeO3 Epitaxial Films
by Guang Xian, Tongxin Zheng, Yaqiu Tao and Zhigang Pan
Materials 2024, 17(11), 2758; https://doi.org/10.3390/ma17112758 - 5 Jun 2024
Cited by 1 | Viewed by 1052
Abstract
LaFeO3 thin films were successfully epitaxially grown on single-crystalline SrTiO3 substrates by the one-step hydrothermal method at a temperature of 320 °C in a 10 mol/L KOH aqueous solution using La(NO3)3 and Fe(NO3)3 as the [...] Read more.
LaFeO3 thin films were successfully epitaxially grown on single-crystalline SrTiO3 substrates by the one-step hydrothermal method at a temperature of 320 °C in a 10 mol/L KOH aqueous solution using La(NO3)3 and Fe(NO3)3 as the raw materials. The growth of the films was consistent with the island growth mode. Scanning electronic microscopy, elemental mapping, and atomic force microscopy demonstrate that the LaFeO3 thin films cover the SrTiO3 substrate thoroughly. The film subjected to hydrothermal treatment for 4 h exhibits a relatively smooth surface, with an average surface roughness of 10.1 nm. X-ray diffraction in conventional Bragg–Brentano mode shows that the LaFeO3 thin films show the same out-of-plane orientation as that of the substrate (i.e., (001)LaFeO3||(001)SrTiO3). The in-plane orientation of the films was analyzed by φ-scanning, revealing that the orientational relationship is [001]LaFeO3||[001]SrTiO3. The ω-rocking curve indicates that the prepared LaFeO3 films are of high quality with no significant mosaic defects. Full article
(This article belongs to the Special Issue Advances in Thin Films Materials: Properties, Characterization, Physical Vapor Deposition and Application)
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<p>Schematic diagram of the preparation process of LaFeO<sub>3</sub>/SrTiO<sub>3</sub> epitaxial thin film.</p> Full article ">Figure 2
<p>X-ray diffraction patterns of powder samples at different hydrothermal temperatures.</p> Full article ">Figure 3
<p>SEM images of powder samples at different reaction temperatures: (<b>a</b>) 280 °C, (<b>b</b>) 300 °C, (<b>c</b>) 320 °C, and (<b>d</b>) 340 °C.</p> Full article ">Figure 4
<p>Elemental distribution of cubic and rod-like grains, (<b>a</b>) Fe, La, O, (<b>b</b>) Fe, (<b>c</b>) O, (<b>d</b>) La.</p> Full article ">Figure 5
<p>Elemental distribution of spherical grains, (<b>a</b>) Fe, La, O, (<b>b</b>) Fe, (<b>c</b>) O, (<b>d</b>) La.</p> Full article ">Figure 6
<p>Surface and cross-section SEM images of LaFeO<sub>3</sub> films at different hydrothermal times: (<b>a</b>) 0.5 h sample surface, (<b>b</b>) 0.5 h sample cross section, (<b>c</b>) 1 h sample surface, and (<b>d</b>) 1 h sample cross section.</p> Full article ">Figure 7
<p>Elemental distribution on the surface of the sample for 0.5 h reaction time.</p> Full article ">Figure 8
<p>Surface and cross-section SEM images of LaFeO<sub>3</sub> films on the SrTiO<sub>3</sub> substrate for 2 h reaction time: (<b>a</b>) surface and (<b>b</b>) cross section.</p> Full article ">Figure 9
<p>Elemental distribution on the surface of the sample for 2 h reaction time.</p> Full article ">Figure 10
<p>XPS-measured spectra of LaFeO<sub>3</sub> thin films: (<b>a</b>) full spectrum, (<b>b</b>) La 3d, (<b>c</b>) Fe 2p, and (<b>d</b>) O 1s.</p> Full article ">Figure 11
<p>Surface and cross-section SEM images of LaFeO<sub>3</sub> films on SrTiO<sub>3</sub> substrate for 4 h reaction time: (<b>a</b>) surface and (<b>b</b>) cross section.</p> Full article ">Figure 12
<p>AFM images of LaFeO<sub>3</sub> films prepared under condition of 4 h reaction time (10 μm × 10 μm).</p> Full article ">Figure 13
<p>(<b>a</b>) Bragg–Brentano X-ray diffraction patterns of LaFeO<sub>3</sub> thin films prepared at 1 h, 2 h, and 4 h, and (<b>b</b>) (002) enlargement of diffraction peaks on the crystal plane.</p> Full article ">Figure 14
<p>φ-scan diffraction pattern of LaFeO<sub>3</sub> {111} and {110} crystallographic families at reaction time of 4 h.</p> Full article ">Figure 15
<p>Rocking curves (ω-scans) of LaFeO<sub>3</sub> (002) crystal surface at reaction time durations of 1 h, 2 h, and 4 h.</p> Full article ">Figure 16
<p>Magnetization hysteresis curves at room temperature for LaFeO<sub>3</sub> thin film at a hydrothermal time of 4 h.</p> Full article ">
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