Refractory materials and coatings for thermal barrier and tribology applications

A growing demand for refractory castables with advanced properties has given rise to a continuous technological evolution and highlighted the necessity for secondary raw materials reapplication even in refractory industry. For the experiment, refractory shotcretes with the same matrix composition were prepared from 30 wt% of high aluminate cement, 40 wt% of bauxite aggregate and 30 wt% of chamotte filler. The request for obtaining a low-cement castable is fulfilled by application of mechanically activated coal ash as microfiller in one of the bauxite shotcretes. The fly ash was activated by means of vibratory disc mill and ultra-centrifugal mill, and results were compared. The shotcrete samples were dried at 110 °C during 24 h to create specimens for investigation of mechanical and thermal properties. The properties have been studied at temperatures ranging from room temperature to adopted maximal temperature 1400 °C. At maximal 1400 °C, the bauxite shotcretes were mainly composed of anorthite, corundum, mullite and cristobalite. Mechanisms of hydration and sintering were investigated by means of differential thermal analysis (DTA) at three different heating rates. DTA measurements showed different activation energies for ordinary bauxite shotcrete and shotcrete with microfiller. The evolution of the refractory shotcretes properties was investigated and correlated with microstructural changes induced by temperature and microfiller addition. The combination of advantages in investigated refractory shotcretes makes them suitable for use in severe conditions at high temperature applications especially in refractory industries.

Cycloid drives are a relatively new group of planetary power transmissions. These transmissions have numerous favorable characteristics, such as a wide range of transmission ratios, very compact design, high reliability in dynamic exploitation conditions, high efficiency, etc. As they are part of a newer generation of transmissions , the possibility of using other materials other than steel in their production is not yet fully investigated. For the purposes of this investigation a single stage cycloid reducer was designed and manufactured out of mainly plastic components. The theoretical efficiency was determined and experimentally tested. Their comparative analysis is given through the discussion. The paper concludes with suggestions for further research on this type of cycloid reducers.

For decades we have hearing that the chemical industry and there also the coating industry, need to break free from its dependency on oil because there are finite resources. Renewable raw materials are constantly under discussion. The paint and coatings industry are focused on innovation and being “green”. Green means a smaller carbon footprint, low VOC content, high renewable content and green processes. The use of renewable ingredients to reduce the carbon footprint, eliminating the use of hazardous materials, introducing biorenewables, incorporating recycled materials, lowering VOC emissions, decreasing energy consumption and reducing waste, while proving it can all be accomplished cost-effectively to become more environmentally responsible. The reduction of environmental damage done by coatings sometimes begins before manufacturing even starts. Research into the carbon footprint of coating materials, or the overall amount of climate-affecting carbon dioxide produced in their manufacture, application, transport and disposal, shows that some coatings simply use fewer resources throughout their life cycles. This paper discusses advances in the use of renewable resources in formulations for various types of coatings. The developments in the application of green and efficient technologies in coating systems are discussed here.

This article provides an overview of the state-of-the-art chemistry and processing technologies for silicon nitride and silicon nitride-rich films, i.e., silicon nitride with C inclusion, both in hydrogenated (SiN x :H and SiN x :H(C)) and non-hydrogenated (SiN x and SiN x (C)) forms. The emphasis is on emerging trends and innovations in these SiN x material system technologies, with focus on Si and N source chemistries and thin film growth processes, including their primary effects on resulting film properties. It also illustrates that SiN x and its SiN x (C) derivative are the focus of an ever-growing research and manufacturing interest and that their potential usages are expanding into new technological areas.

Although refractory high-entropy alloys have exceptional strength at high temperatures, they are often brittle at room temperature. One exception is the HfNbTaTiZr alloy, which has a plasticity of over 50% at room temperature. However, the strength of HfNbTaTiZr at high temperature is insufficient. In this study, the composition of HfNbTaTiZr is modified with an aim to improve its strength at high temperature, while retaining reasonable toughness at room temperature. Two new alloys with simple BCC structure, HfMoTaTiZr and HfMoNbTaTiZr, were designed and synthesized. The results show that the yield strengths of the new alloys are apparently higher than that of HfNbTaTiZr. Moreover, a fracture strain of
12% is successfully retained in the HfMoNbTaTiZr alloy at room temperature.

This paper reviews how ethnographic studies (ethnoarchaeology) of iron smelting in NW Tanzania were used alongside archaeological evidence to document the development of a highly efficient iron smelting technology. Based on the principle of preheating the air blast, this invention occurred over a 150 year period of experimentation during the early first millennium CE--long before similar principles were applied to iron technology in Europe.
One of the most significant discoveries for the history of science in Africa and for African history, it has since been depreciated and misrepresented in several scholarly settings. This paper reviews these errors and misrepresentation and replaces them with an explicit and evidence-based narrative that reaffirms their importance to science, history, and the well-being of African peoples.

Carbon-bonded refractories are widely used in steel industry. They are well known for their outstanding thermal shock behavior. The knowledge of the elastic properties at high temperatures will make simulations for thermal shock more effective or contribute to understand the material behavior based on its micro structural components as well as the contribution of each one. In this work measurements of the Young’s modulus of elasticity at high temperatures of carbon-bonded alumina refractories with two different amounts of carbon obtained by impulse excitation technique have been investigated. The measurements showed a significant increase of the Young's modulus of elasticity up to 1450°C independently of the carbon amount.  Furthermore, a clear hysteresis during cooling was observed.

Many food ingredients and additives can be used to improve fried food, but hydrocolloids are the principal category of functional ingredients that have been used for the past forty years. This is incompatible with recent consumer trends towards healthier food and low fat products. The consumption of oil and saturated fat, in particular is related to significant health problems, including coronary heart disease, cancer, diabetes, and hypertension. Hydrocolloids play two main roles in fried food development. It is one of form a fine invisible coating, practically on their own, when their main purpose is to avoid excessive oil absorption during the pre-frying and frying processes. In the other, when they are added to the batter among its other ingredients, they are used to avoid oil absorption too, but they also act as viscosity control agents, improve adhesion, pickup control and freeze-thaw stability or help to retain the crispness of the battered/breaded fried foods. Therefore, the use of techniques aimed at reducing the oil uptake by food, will reduce or eliminate the risks associated with the transfer of toxic and carcinogenic components, such as acrylamide. This article reviews the wide range of functions that hydrocolloids perform in fried foods.

Problem of boiler component erosion is a very complex and present in practically all fossil fuel power plants burning low heating value coals irrespective of their particular design and operating characteristics. Major fly coal erosion accelerating factors are large amounts of abrasive components in the air-coal mixture and its high velocity. In general terms, there is a trend of implementation of appropriate erosion protection in critical place of pulverized boiler coal preparation equipment. In this paper are presented results of erosion tests provided on samples with different erosion protection materials. Erosion damage profiles of different protection materials were investigated and analyzed on tested samples.

Conventional duplex (DL) and functionally graded (FG) LaTi2Al9O19 (LTA) coatings were deposited over
C263 nickel alloy by air plasma spray (APS) and compared with subsequent laser glazing processes. The
effect of laser glazing on adhesion strength and thermal barrier performance was investigated. The
thermal barrier effect was measured using the temperature difference technique involving infrared (IR)
rapid heater and the adhesion strength was measured using the scratch tester. The surface morphology
and microstructure were analyzed by optical microscopy (OM), Scanning Electron Microscope (SEM) and
3D profilometer. Based on the experimental results, the laser glazing showed a remarkable temperature
drop after IR rapid heating. The changes in porosity and grain refinement make more contributions to the
temperature drop of the laser-glazed coatings than that of as-sprayed coatings. The temperature drop is
about 110°C for laser-glazed LTA FG coating after 100 s of IR flash, while the drop in DL as-sprayed
coating is 60°C compared to the base material.

The International Conference on Tribology-BALKANTRIB is supported by the Balkan Tribological Association and is organized every three years since 1993, each time in different Balkan country. This 10th jubilee BALKANTRIB conference is organized by the Serbian Tribology Society and the Faculty of Mechanical Engineering in Belgrade. The scope of the Conference embraces the state-of-the-art and future trends in tribology research and application. Tribology as an interdisciplinary scientific area is always in the core of research and industrial interests, and the Conference aims to stimulate the collaboration between scientists, researchers, industrial engineers and specialists. The Conference will focus on both the fundamental and applied aspects of friction, wear and lubrication, at all scales. Contributions all over the world, involving any aspect of tribology are welcome. Topics: Fundamentals of friction and wear Tribological properties of solid materials Surface engineering and coating tribology Lubricants and lubrication Tribotesting and tribosystem monitoring Tribology in machine elements Tribology in manufacturing processes Tribology in transportation engineering Design and calculation of tribocontacts Sealing tribology Biotribology Nano and microtribology Other topics related to tribology WELCOME TO BALKANTRIB '20!

The mechanism of aluminum titanate (tialite) based solid solutions formation in the MgO·Al2O3-Fe2O3·TiO2-Al2O3·TiO2 pseudo ternary system was studied. The tialite is the main mineralogical component in the system and besides this, two other components are formed (magnesium spinel and iron titanate), which decrease its temperature of formation and improve the thermodynamic stability. Depending on the composition and firing temperature two types of solid solutions are obtained; a ternary (Fe,Al)2TiO5 and a quaternary (Mg,Fe,Al)2TiO5 solid solution. All samples have a good sintering behaviour during the thermal treatment nevertheless without additives, tialite formation is accompanied by great volume increasing. The sintering of all samples starts at 1300°C. After thermal treatment, the samples have a reduced open porosity and the average pore radius is about 0,1 μm.

Call for papers 4th International Conference on Advances in Mechanical Engineering (AME 2018) will provide an excellent international forum for sharing knowledge and results in theory, methodology and applications impacts and challenges of Mechanical Engineering. The conference documents practical and theoretical results which make a fundamental contribution for the development of Mechanical Engineering. The aim of the conference is to provide a platform to the researchers and practitioners from both academia as well as industry to meet and share cutting-edge development in the field. Topics of interest include, but are not limited to, the following : Authors are solicited to contribute to the conference by submitting articles that illustrate research results, projects, surveying works and industrial experiences that describe significant advances in the following areas, but are not limited to

Accelerating interest in silicon nitride thin film material system continues in both academic and industrial communities due to its highly desirable physical, chemical, and electrical properties and the potential to enable new device technologies. As considered here, the silicon nitride material system encompasses both non-hydrogenated (SiNx) and hydrogenated (SiNx:H) silicon nitride, as well as silicon nitride-rich films, defined as SiNx with C inclusion, in both non-hydrogenated (SiNx(C)) and hydrogenated (SiNx:H(C)) forms. Due to the extremely high level of interest in these materials, this article is intended as a follow-up to the authors’ earlier publication [A. E. Kaloyeros, F. A. Jové, J. Goff, B. Arkles, Silicon nitride and silicon nitride-rich thin film technologies: trends in deposition techniques and related applications, ECS J. Solid State Sci. Technol., 6, 691 (2017)] that summarized silicon nitride research and development (R&D) trends through the end of 2016. In this survey, emphasis is placed on cutting-edge achievements and innovations from 2017 through 2019 in Si and N source chemistries, vapor phase growth processes, film properties, and emerging applications, particularly in heterodevice areas including sensors, biointerfaces and photonics.

Malaysia is situated at the equatorial region with an average solar radiation of 400-600 MJ/m 2 per month. It has a promising potential to establish large scale solar power installations; however, solar energy is still at the infancy stage due to the high cost of photovoltaic (PV) cells and solar electricity tariff rate. The Malaysian government is keen to develop solar energy as one of the significant sources of energy in the country. According to the 9th Malaysia Plan (9MP), a large allocation had been dedicated for implementation of solar PV systems. On 25th July 2005, a Malaysian Building Integrated Photovoltaic (MBIPV) project had been announced and it was planned to end by 2010. The project consists of three categories which include: BIPV demonstration, national "SURIA1000" and BIPV showcase. Greater emphasis will be placed on energy efficiency under the Tenth Malaysia Plan (2011-2015). This paper discusses present and future situation of solar power in Malaysia, utilization of solar energy and the strategies taken by the Malaysian government and Non-Government Organizations (NGOs) to promote solar energy thermal applications and electricity power generation in the future.

In the present study, reduced graphene oxide (rGO)/titanium dioxide (TiO 2) composite coatings were successfully prepared on titanium substrate by applying plasma electrolytic oxidation (PEO) process and the effect of anti-corrosion ability of rGO nanosheets synthesized by modified Hummer's method on the physical properties, corrosion and Mott-Schottky behaviors of the coatings was investigated. Structural, composition and morphological characteristics confirmed the full incorporation of large-area rGO nanosheets into the TiO 2 coatings with pancake-like morphology. By increasing rGO concentration, the thickness of the coatings was found to increase; whereas both roughness and porosity gradually reduced, compared to the pure TiO 2 sample. Meanwhile, the wettability properties revealed a high hydrophobic behavior with a contact angle larger than 90°. The electrochemical measurements using potentiodynamic polarization test featured that the polarization resistance (R p) experienced a considerable increase from 1.88 × 10 5 to 195.3 × 10 5 Ω•cm 2 , with the increment of rGO nanosheets content up to 0.5 g•L −1. While the Mott-Schottky analysis indicated that the rGO nanosheets incorporation drastically diminished the donor concentration of the samples. These results verified that introducing rGO nanosheets into the PEO prepared TiO 2 coatings significantly enhanced the anti-corrosion performance of rGO/TiO 2 composite coatings, suggesting a tremendous corrosion barrier effect of the coatings.

The removal of macro-burrs formed after drilling has always been a difficult engineering problem, especially on different-machined materials with through holes. This paper aims at presenting an investigation into hole exit characteristics of Ti6Al4V drilled. Plastic deformation at the end of the cutting process or blanking results into the forming of burr, whose degree of impact is mostly affected by the processing parameters, especially the axial feed. Series experiments were conducted to analysis the effect of processing parameter on formed burr. The volume of burr has great effect on work-piece quality and product cost, the burr height formed easily decreases because great attention from scholars and engineers has been paid to, while the burr width size despised naturally plays a great influence on product quality and machining cost. The new de-burring tool are designed and applied in experiment, the decrease in burr width is obviously found, so the removal of burrs becomes much little than that gotten in traditional tool. The resulting indicates a promising future of de-burring in practical application Journals.

""(EN)Compositions are disclosed containing a solvated viscoelastic polymeric gel diluted into an ionically conductive aqueous solution which can be usefully applied to any surface that is hydrophobic to act, for example, as an antifogging coating with minimal optical distortion and excellent transparency. The compositions can also be used as lubricious agents on medical implants, shunts, and surgical supplies to minimize tissue trauma, to maximize bio-compatibility, and to increase healing by enhancing better irrigation and flow in adjacent tissue.
(FR)L'invention porte sur des compositions contenant un gel polymère viscoélastique solvaté, dilué dans une solution aqueuse ioniquement conductrice qui peut être utilement appliquée sur toute surface qui est hydrophobe, pour servir, par exemple, de revêtement antibuée avec une distorsion optique minimale et une excellente transparence. Les compositions peuvent également être utilisées en tant qu'agents lubrifiants sur des implants médicaux, des dérivations, et des fournitures chirurgicales, pour rendre minimal le traumatisme tissulaire, pour rendre maximale la biocompatibilité et pour augmenter la cicatrisation par une meilleure irrigation et une amélioration de la circulation dans le tissu adjacent""

Нові вимоги до експлуатаційних систем літальних апаратів, поряд із постійно зростаючим тиском на зменшення споживання палива, забруднюючих речовин та викидів шуму, суттєво сприяють пошуку нових та більш чистих технологій, паливні елементи яких демонструють великий потенціал. В роботі показано досягнутий рівень розробок тонкоплівкових композиційних матеріалів з використанням іонно-плазмових і плазмохімічних методів на АТ «ФЕД», що створює передумови зміни властивостей по відношенню до традиційних матеріалів на 2…3 і більше порядків, зниження робочої температури до 400…600ºС. Це дає змогу розробляти принципово нові конструкції тонкоплівкових паливних елементів (товщиною в 10–20 разів менше, ніж трубчастий варіант) і серійноздатні технології їх виготовлення в наступних напрямках: нанесення тонкоплівкових композицій на розроблену конструкцію з урахуванням технологічних обмежень для різних методів осадження; отримання композиційних матеріалів, що складаються з шарів: газощільного електроліту і електродних шарів з тонкоплівковими струмознімальними контактами; забезпечення поділу газових сумішей керамічним шаром електроліту при товщині < 50…20 мкм; мінімізація товщини плівкового електроліту та інших функціональних шарів паливної комірки; підвищення міцності зчеплення шарів і корозійної стійкості струмознімальних контактів і електродних шарів в робочих середовищах для забезпечення працездатності конструкції протягом всього процесу експлуатації. Ключові слова: тонкоплівковий паливний елемент, іонно-плазмові методи, літак, електрична енергія.

There is a growing need to preserve sources of energy in all sectors of industrial economy. Therefore, reducing frictional losses is seen as a crucial aim. Traditionally, lubrication has been viewed as the main driving force behind this quest. By the turn of 20th century molecular interaction of lubricants near boundary solids began to be understood as we have pointed out in the Introduction to our contribution to this Special Issue of the journal. Those early findings have gradually led to the importance of lubricant–surface combination, when viewed as a system. Progressively, much more research has been devoted to the issue of lubricant composition, particularly the design of lubricant additive packages. At the same time, the role that surface topography plays on the generation of friction has evolved from the very basic Amontons’ laws of friction of dry sliding surfaces. It has become clear that those laws do not entirely apply to the lubricated rough surfaces. In fact, it has emerged that nature itself makes use of rough surface topography for retention of a film of low shear strength fluid in many cases, including in all the mammalian endo-articular joints where relatively rough soft articular cartilage elastically deforms and causes pressure perturbations that enhance the load carrying capacity of the synovial fluid as well as reducing friction by its entrapment between its rough topography. This phenomenon was subsequently termed as micro-elastohydrodynamics. It has, therefore, become clear that rough surface topography can in fact help reduce friction, unlike the case of dry sliding contacts. This realisation, in time, has led to the introduction of engineered surfaces, either through fundamental understanding or simply through intuition. There are many underlying mechanisms for enhanced lubrication, such as pressure perturbation mentioned above, as well as micro-wedge effect, formation of micro-reservoirs of lubricants and others. As the lubricant–surface combination is progressively viewed as a system at the micrometre and nanometre interaction scales, significant advances are being made in use of surface topography, lubricant rheology and physical chemistry, tribo-chemistry, surface coatings, etc. Furthermore, the area of application of these technologies is spreading rapidly as discussed by the contributions made to this Special Issue by our learned colleagues. We are very grateful for their insights shared with the tribology community in this unique volume of work. Clearly, an important task ahead is to gain more insight into the underlying mechanisms of friction at different physical scales in order to be able to optimise the system to particular applications. This would be similar to biomimetic approach as nature itself has used with almost the same physical chemistry and surface topographical attributes in an evolutionary manner to meet the operational integrity of many natural systems.

The development of metal deposition processes based on electroless nickel, alloy and composite coatings on various surfaces has witnessed a surge in interest among researchers, with many recent applications made possible from many excellent properties. In recent years, these coatings have shown promising corrosion and wear resistance properties and large number of newer developments became most important from macro to nano level applications. After a brief review of the fundamental aspects underlying the coating processes, this paper discusses in detail about different electroless nickel alloy, composite, nano plating, bath techniques, preparation, characterization, new depositing mechanism and their recent applications, including brief notes on difficult substrate and waste treatment for green environment. Emphasis will be onto their recent progress, which will be discussed in detail and critically reviewed.

Problem of boiler component erosion is a very complex and present in practically all fossil fuel power plants burning low heating value coals irrespective of their particular design and operating characteristics. Major fly coal erosion accelerating factors ...

It is generally accepted that calcium phosphate (CaP) is one of the most important biomaterials in implant coating applications mainly because of its excellent bioactivity. However, its relatively poor mechanical properties limits its application. This entails that a better understanding of the mechanical properties of a CaP coating is a must especially its behavior and the mechanisms involved when subjected to stresses which eventually lead to failure. The mechanical properties of the coating may be evaluated in terms of its adhesion strength. In this study, a radio frequency-magnetron (RF-MS) sputtering technique was used to deposit CaP thin films on 316L stainless steel (SS). The coatings were subjected to series of microscratch tests, taking careful note of its behavior as the load is applied. The adhesion behavior of the coatings showed varying responses. It was revealed that several coating process-related factors such as thickness, post-heat treatment and deposition parameters, to name a few, affect its scratching behavior. Scratch testing-related factors (i.e. loading rate, scratch speed, scratch load, etc.) were also shown to influence the mechanisms involved in the coating adhesion failure. Evaluation of the load-displacement graph combined with optical inspection of the scratch confirmed that several modes of failure occurred during the scratching process. These include trackside cracking, tensile cracking, radial cracking, buckling, delamination and combinations of one or more modes.

http://www.sciencedirect.com/science/article/pii/S1751616110000044

Malaysia is situated at the equatorial region with an average solar radiation of 400–600MJ/m2 per month. It has a promising potential to establish large scale solar power installations; however, solar energy is still at the infancy stage due to the high cost of photovoltaic (PV) cells and solar electricity tariff rate. The Malaysian government is keen to develop solar energy as one of the significant sources of energy in the country. According to the 9th Malaysia Plan (9MP), a large allocation had been dedicated for implementation of ...

This paper describes erosion characteristics of high velocity oxy fuel (H.V.O.F.) along with commonly used steels 16Cr5Ni in Turbine and studied the comparison the effect of erosion at Different Velocities of the slurry on Cr 2 O 3 and CrC-NiCr coating on steel. The four different ranges of velocity is taken i.e. 35m/s, 50m/s ,60and 70m/s. at normal impact angle and comparison regarding the erosion resistance was determined from the mass loss results. Higher erosion takes place at medium range of velocity i.e. at 50 m/s. Based on this experimental study coating was considered acceptable for the processes employed

This paper describes erosion characteristics of high velocity oxy fuel (H.V.O.F.) along with commonly used steels 16Cr5Ni in Turbine and studied the comparison the effect of erosion at Different Velocities of the slurry on Cr 2 O 3 and CrC-NiCr coating on steel. The four different ranges of velocity is taken i.e. 35m/s, 50m/s ,60and 70m/s. at normal impact angle and comparison regarding the erosion resistance was determined from the mass loss results. Higher erosion takes place at medium range of velocity i.e. at 50 m/s. Based on this experimental study coating was considered acceptable for the processes employed

The removal of macro-burrs formed after drilling has always been a difficult engineering problem, especially on different-machined materials with through holes. This paper aims at presenting an investigation into hole exit characteristics of Ti6Al4V drilled. Plastic deformation at the end of the cutting process or blanking results into the forming of burr, whose degree of impact is mostly affected by the processing parameters, especially the axial feed. Series experiments were conducted to analysis the effect of processing parameter on formed burr