PROJECT2018 FullReport
PROJECT2018 FullReport
PROJECT2018 FullReport
A PROJECT REPORT
Submitted by
BALAKUMARAN J (412514114042)
RAJA G (412514114149)
SHYAM V S (412514114182)
SRIRAMA DURGESH M (412514114194)
of
BACHELOR OF ENGINEERING
in
MECHANICAL ENGINEERING
APRIL 2018
i
ANNA UNIVERSITY : CHENNAI 600 025
BONAFIDE CERTIFICATE
BALAKUMARAN J (412514114042)
RAJA G (412514114149)
SHYAM V S (412514114182)
SIGNATURE SIGNATURE
DR. A. RAJENDRA PRASAD MR. V. RAVI RAJ
HEAD OF THE DEPARTMENT SUPERVISOR
Assistant Professor
Department of Mechanical Engineering Department of Mechanical Engineering
Sri Sairam Engineering College Sri Sairam Engineering College
Chennai- 600 044 Chennai- 600 044
ii
ACKNOWLEDGEMENT
iii
ABSTRACT
With the increasing dependence on metals, it has become the need of the
annihilations. Metals have been proven earnest for their exceptional properties
of being lustrous, high density, high tensile strength, and high melting point and
also possessing good conductive properties. But they have their own downfalls,
materials paradigm. They are chemically resistant, acts as a good insulator and
they are light in weight. Garnishing our interest is the ability of the polymers to
properties, such as Low Density, eminent have come out with ideas of suffusing
Carbide with PMMA, mechanical properties of the materials get enhanced and
iv
TABLE OF CONTENTS
ABSTRACT iv
LIST OF FIGURES x
LIST OF ABBREVATIONS
1. INTRODUCTION 01
1.1 POLYMER MATRIX COMPOSITES 01
1.2 PROCESSING OF PMCs 01
1.3.3 Pultrusion 05
v
1.5 PROPERTIES OF PMCs 11
1.5.1 Mechanical Behaviour 11
1.5.1.2 Frracture
1.6 APPLICATIONS 13
2. LITERATURE REVIEW 15
2.1 LITERATURE 15
2.2 SUMMARY 24
3. MATERIAL SELECTION 32
vi
3.1.5 Structure of SiC polytypes 38
3.1.6 Properties of SiC polytypes 39
3.2 SELECTION OF POLYMER 40
4. FABRICATION OF LAMINATES 49
4.1.3 Applications 51
4.2.2 Applications 55
vii
4.3 HAND LAY-UP 56
4.3.1 Mould 56
4.3.7.1 Operation 61
5. TESTING OF SPECIMEN 63
5.1 TESTS PERFORMED 63
viii
5.1.6 Purpose of Flexural Test 64
6. COST ANALYSIS 77
7. COROLLARIES PERTAINING TO 80
EXPERIMENT
8. CONCLUSION 81
REFERENCES 82
ix
LIST OF FIGURES
x
4.2 INJECTION MOULD MAKING 49
DIAGRAMMATIC REPRESENTATION OF
4.3 52
COMPRESSION MOULDING MACHINE
xi
LIST OF TABLES
xii
CHAPTER 1
INTRODUCTION
1
process that requires much shorter time cure cycles. Curing by electron beam
occurs by electron-initiated reactions at a selectable cure temperature.
There are many processing methods for composites with therrnoset matrix
materials including epoxy, unsaturated polyester, and vinyl ester.
Hand Lay-up and spray techniques are perhaps the simplest polymer-processing
techniques. Fibres can be laid onto a mold by hand and the resin (unsaturated
polyester is one of the most common) is sprayed or brushed on. Frequently,
resin and fibres (chopped) are sprayed together onto the mold surface. In both
cases, the deposited layers are densified with roller. Figure 2.2 shows
schematics of these processes. Accelerators and catalysts are frequently used.
Curing may be done at room temperature or at a moderately high temperature in
an oven.
2
storage) vessels are built by filament winding. Glass, carbon, and aramid fibres
are routinely used with epoxy, polyester, and vinyl ester resins for producing
filament wound shapes.
There are two types of filament winding processes: wet winding and prepreg
winding. In wet winding, low-viscosity resin is applied to the filaments during
the winding process. Polyesters and epoxies with viscosity less than 2 Pa 5
(2000 centipoise) are used in wet winding. In prepreg winding, a hot-melt or
solvent-dip process is used to preimpregnate the fibres. Rigid amines, novolacs,
polyimides, and higher-viscosity epoxies are generally used for this process. In
filament winding, the most probable void sites are roving cross-overs and
regions between layers with different fibre orientations.
Fig. 1.1( b) Schematic of a filament wound pressure vessel with a liner; helical
and hoop winding are shown.
3
Fig. 1.2( a) In Hand Lay-up, fibres are laid onto a mould by hand, and the
resin is sprayed or brushed on.
Fig. 1.2 ( b) In spray-up, resin and fibres (chopped) are sprayed together onto
the mould surface.
4
1.3.3 Pultrusion
5
Fig 1.3 Schematic of the Pultrusion Process
6
With the aid of woven, stitched, or braided preforms, fibre volume
fractions as high as 60% can be achieved.
The process involves a closed mold; therefore styrene emissions can be
reduced to a minimum.
Mold design is a critical element in the RTM process. Generally, the fibrous
preform is preheated and the mold has built-in heating elements to accelerate
the process of the resin. Resin flow into the mold and the heat transfer are
analyzed numerically to obtain an optimal mold design. The automotive
industry has found that the RTM can be a cost-effective, high-volume process
for large-scale processing.
7
midair, is cut to the correct shape by cutting blades. The cutting blades can
make 6000 cuts per minute. The cut pieces of tape are caught between two new
rolls of paper and film and rewound onto a new spool, called a cassette. The
cassette is then taken to the second machine for lay-up. A laser beam in the
tape-laying head is used to accurately lay the tape on the mold.
In fibre placement techniques, individual prepreg tows from spools are fed into
the fibre placement head, where they are collimated into a single fibre band and
laminated onto the work surface. Each tow is about a 3-mm-wide strand of
continuous fibres. A strand, in turn, consists of 12,000 individual filaments
impregnated with an epoxy resin. Different tows can be delivered at different
speeds, allowing a conformation of a complex structure. A compaction roller or
shoe consolidates the tape, pressing it onto the work surface. This pressing
action serves to remove any trapped air and any minor gaps between individual
tows. Figure 1.4 shows a schematic of the fibre placement process.
8
1.4 INTERFACES IN PMCs
Below are the summary of some important features of the interface region in
PMCs with glass, aramid, and polyethylene fibres.
Silica-based glasses are analogous to many organic polymers, in that they are
amorphous. Crystalline silica melts at 1800°C and can be worked in the range of
1600-1800 °C. However, by adding some metal oxides, one can break the Si-O
bonds and obtain a series of amorphous glasses with low glass transition
temperatures so that they can be processed at much lower temperatures than
pure silica. In general, the atomic or molecular arrangement in any material is
different at the surface than in the interior. In particular, in the case of silica-
based glasses containing a variety of oxides, a complex hydroxyl layer is
formed rather easily. Non hygroscopic oxides absorb water as hydroxyl groups
while hygroscopic oxides become hydrated. The activity of a glass surface is
thus a function of the hydroxyl content and the cations just below the surface.
That is, the surface activity of E-glass will be different from that of fused silica.
Invariably, glass fibres are surface treated by applying a size on the freshly
drawn glass fibres to protect them from the environment, for handling ease, and
to avoid introducing surface defects. Common sizes are starch gum,
hydrogenated vegetable oil, gelatin, polyvinyl alcohol (PVA), and a variety of
nonionic emulsifiers. The size is generally incompatible with the matrix resin
and is therefore removed before putting the glass fibres in a resin matrix by heat
cleaning at ~ 350°C for 15 to 20 hours in air, followed by washing with
detergent or solvent and drying. After cleaning, organometallic or organosilane
coupling agents are applied; an aqueous solution of silane is commonly used for
this purpose. Examples of coupling agents commonly used are organometallic
or organosilane complexes. During the drying of sized glass fibres, water is
9
removed and a condensation reaction occurs between silanol and the glass
surface and between adjacent silanol molecules on the glass surface, leading to a
polysiloxane layer bonded to the glass surface.
Most polymers show rather poor adhesion to aramid fibres. This is evidenced by
the generally poor interlaminar shear strength and transverse tensile strength
values obtained with aramid reinforced PMCs. Typically, aramid/epoxy
interfacial strengths are about half of the interfacial strengths of glass/epoxy or
carbon/epoxy composites. A highly oriented chain micro-structure and skin/core
heterogeneity are responsible for this low, poor interfacial strength. This may
not be a disadvantage in aramid/polymer composites used to make impact-
resistant items such as helmets or body armor, where ease of delamination may
be an advantage. However, in high-strength and high-stiffness composites, poor
interfacial adhesion can be a disadvantage. Various fibre surface treatments
have been tried to alleviate this problem.
10
1.4.3 Polyethylene Fibre/Polymer Interface
Chemical treatment with chromic acid and plasma etching in the presence of
oxygen are two treatments that are commonly used to modify the surface
characteristics of polyethelene fibre with a view to improve their adhesion to
polymeric matrix materials.
The properties of a composite will depend on the matrix type, fibre type,
amount or volume fraction of matrix (or that of the fibre), fabrication process,
and the orientation
11
also small. Aramid fibre has superior impact characteristics; therefore, aramid
fibre-based polymer composites will show better ballistic resistance against
impact resistance in general. Similar observations can be made regarding
strength characteristics of the polymer matrix composites. High damping or the
ability to reduce vibrations can be very important in many applications.
There are, however, two fundamental effects that must be taken into account
when designing components made of PMCs, namely, temperature and humidity.
The combined effect of these two, that is, hygrothermal effects, can result in a
considerable degradation in the mechanical characteristics of the PMCs.
Degradation owing to ultraviolet radiation is another important environmental
effect breaking the covalent bonds in organic polymers results in a slight
increase in strength, followed by a gradual loss of strength due to laminate
surface degradation.
1.5.1.2 Fracture
12
Generally, stiffness and strength of a PMC increase with the amount of stiff and
strong matrix introduced in a polymer. The same cannot be said unequivocally
for the fracture toughness. The toughness of the matrix and several micro
structural factors related to the fibres and the fibre/matrix interface have a
strong influence on the fracture toughness of the composite.
The final stage in any PMC fabrication is called debulking, which serves to
reduce the number of voids. Nevertheless, there are some common structural
defects in PMCs. Following is a list of these:
1.6 APPLICATIONS
PMMA is an economical, versatile general purpose material. Various types of
acrylics are used in a wide variety of fields and applications, including:
13
4. Office equipment: Writing and drawing instruments, pens;
14
CHAPTER 2
LITERATURE REVIEW
2.1 LITERATURE :
This chapter covers the literature review of results obtained from Experimental
Investigation of mechanical behaviour of Poly Methyl methacrylate (PMMA)
based polymer composites with Silicon Carbide (SiC). Apart from the polymer
composite, reinforcement used, manufacturing methods, this survey includes the
developments in the mechanical behaviour of polymer based composites at
different compositions of SiC reinforcements.
15
Chao Shi et.al (2013) discussed about the synthesis of a polymer based
composite with an inorganic reinforcement with the help of free radical
polymerization in batch technique. -Si3N4 fibres, PMMA were selected as the
inorganic reinforcement constitution and polymer matrix, respectively. Free
radical polymerization in batch was the main method to synthesis composite by
utilizing azodiisobutyronitrile (AIBN) as the initiator, with the advantages of
simple productive process, free of post-process and high purity. Before that,
Si3N4 fibres were modified with g-methacryloxypropyltrimethoxysilane (g-
MPS) to ensure the uniformly distribution in the PMMA matrix. The influence
of surface modification on the molecular level and mechanical properties was
investigated through FTIR, TG-DSC and nano indentation. The results showed
that silane coupling agent facilitated the linkage between Si3N4 fibres and
PMMA matrix, with an obviously increase of elastic modulus and micro-
hardness.
16
The effect of microwave heating on thermal stability of polymer nanocomposite
was also been studied.
17
pulverizing carbon fibre reinforced plastics (CFRP). PMMA particles were
adsorbed on the carbon fibre surfaces via electrostatic interactions, to promote
the interfacial adhesion between the carbon fibres and the PMMA resin and
thereby improve the dispersion of the fibres in the resin. This enhanced the
mechanical properties of the composites; the yield stress and elastic modulus of
the composite.
He Runqin et.al (2017), investigated the effect of TiO 2 fillers on the mechanical
properties of CNT/PMMA composites. Different types of polymers show
different mechanical behaviour. However, neat polymer is very rarely used as
bearing materials and wear resistant materials because of unmodified polymer
could not satisfy the demands arising from the situations where in a
combination of good mechanical properties is required. The bidirectional fabric
reinforcement offered a unique solution to the ever-increasing demands on the
advanced materials in terms of better performance and ease in processing.
18
Eduard A. Stefanescu et.al (2011), investigated the Fibreglass-reinforced
polymer composites for potential use as structural dielectrics in multifunctional
capacitors that require simultaneous excellent mechanical properties and good
energy storage characteristics. In recent years substantial efforts have been
dedicated to finding new alternatives for performance, weight and volume
improvements in batteries and capacitors. While commercial ceramic capacitors
are typically employed where small sizes along with high capacitances and
insulation resistances are required, they are not intended for precision
applications due to high variations in the capacitance with temperature. In
contrast, polymer film capacitors are predominantly used in applications
requiring low dielectric absorption and loss factors over a wide temperature
range. However, polymer film capacitors are characterized by smaller
capacitances due to their lower dielectric constants compared to the ceramic
counterparts. PMMA-fibreglass structural dielectrics containing neat or
PEDOT:PSS-coated BaTiO3 particles was focused, for potential use in
multifunctional capacitors that require superior stiffness and energy storage
characteristics. The multifunctional capacitors could be potentially employed as
substitutes for static load-carrying components in traditional structures (e.g.,
hybrid vehicles or airplanes) with the purpose of reducing the overall system
weight and/or volume.
Garima Mittal et.al (2016), came out with a research study of processing
PMMA/polyimide (PI)/hexagonal boron nitride (hBN) composites by
incorporating PI and hBN powder into the PMMA matrix. Hexagonal boron
nitride (hBN), also known as white graphite, is a layered ceramic compound
that is an isoelectric analog to graphite, with an identical hexagonal lattice
structure. Due to its very close similarity with graphite, it shows remarkable
thermal and chemical stability along with the same favorable mechanical
properties that facilitate applications in high temperature equipment. Among all
19
the boron nitrides, the hexagonal form is the most stable and is soft enough to
be used in lubrication. PMMA/PI polymer composites reinforced with silane-
functionalized hBN powder possesses a special position because of very good
environmental stability like, moisture resistance, UV resistance, scratch
resistance etc. Along with these PMMA possesses good mechanical properties,
optical clarity, low friction coefficient. Polyimide (PI) is considered as high
performance thermoplastic material because it owns unique structure due to the
formation of charge transferring complex within the molecules that gives rise to
ordered intermolecular stacking. Consequently, it displays outstanding thermal
and mechanical properties along with the good chemical and radiation
resistance and electronic properties.
H. Varela-Rizo et.al (2011), studied the effect of different functional groups and
processing techniques in the properties of CNF/poly(methyl methacrylate)
(CNF/PMMA) composites. Carbon nanofibres (CNFs) emerged as an
economical alternative to carbon nanotubes (CNTs) with similar characteristics:
high aspect ratio and combination of unique mechanical and electrical
properties. Therefore, all these carbon nanofilaments have been considered for
enhancing polymer properties in nanocomposites, providing conductivity and
reinforcement. Modification of CNF and CNT surface through functionalization
has been a common way of improving dispersion and providing effective
compatibility with the matrix. Melt-compounding, solvent casting and in situ
polymerization in PMMA composites containing pristine, carboxylated and
amino-functionalized CNFs were compared. Mechanical properties and
rheological behavior of the composites revealed a strong filler–polymer
interface interaction in the in situ polymerized composites, even through
covalent binding.
Jialiang Wang et.al (2012), investigated about the Solvent exfoliated graphene
for reinforcement of PMMA composites prepared by in situ polymerization.
20
Graphene (GP), a two-dimensional platelet consisting of sp2-hybridized carbon
atoms arranged in a perfect honeycomb lattice, has triggered enormous research
interest in both fundamental and applied science communities. Due to its
excellent electrical, thermal and mechanical properties, GP has great potential in
applications of sensors, super capacitors, thin conductive films, rechargeable
lithium ion batteries, and polymer composites. Graphene (GP)-based polymer
nano composites have attracted considerable scientific attention due to its
pronounced improvement in mechanical, thermal and electrical properties
compared with pure polymers. to direct exfoliation of graphite in NMP and
covalently functionalizing GP with PMMA (GPMMA) via in- situ free radical
polymerization, and the density of grafted PMMA can be tuned by changing the
feed ratio of GP and methyl meth-acrylate (MMA). GPMMA is of high-quality
with few defects since it is absent from violent and complicated modification
(compared with GO or CMG), and such a perfect structure renders GPMMA an
outstanding reinforcing agent. Additionally, after grafting with PMMA chains,
the functionalized GP is soluble in various solvents (such as NMP, THF and
DMF) and remains stable for a long period of time (over one month), which
also facilitates preparing different kinds of composites.
Jun-long Wang et.al (2009) et.al, did a study on SiO 2/PMMA/CE tri-component
interpenetrating polymer network composites. The interpenetrating polymer
network (IPN) is a unique polymer blend that is formed by two or more
crosslinked polymers through interpenetrating and winding. It is disordered
crosslinked networks in which at least one polymer network forms crosslinked
framework after another has already been formed. IPN is actually a concrete
structure form of macromolecule alloy metals or a special combination mode
among different polymers. CE was modified by CTC-IPN and interface
conjugated interpenetration. A conjugated tri-component penetrating polymer
composite was prepared, in which CE was used as the public network and it was
21
interpenetrated and winded with PMMA and nanometer SiO 2 one another. The
microstructure of the composite was characterized by infrared spectroscopy (IR)
and transmission electron microscopy (TEM). The mechanical properties were
measured in German-made DL-1000B and XCL-40 universal material test
machines, respectively.
A. Akinci et.al (2013), realized the friction and wear performance of pure poly
(methyl methacrylate) (PMMA) and zirconium oxide (ZrO 2) filled PMMA
composites under dry sliding conditions. PMMA resin exhibits better impact
and mechanical and physical properties than other polymer materials. However,
the material possesses poor mechanical and physical properties when used
alone, where it is easily broken into parts during an accident, or when a patient
applies high mastication force on the denture base. Zirconium dioxide possesses
excellent properties like: high strength, high fracture toughness, excellent wear
resistance, high hardness, and excellent chemical resistance. Hence, ZrO 2-
nanoparticles appear as an attractive option to be used as reinforcement of
polymers, in order to produce composites with enhanced performance.
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2.1.1 Development Objectives
For other applications different development objectives are given, which differ
from those mentioned before. For example, in medical technology, mechanical
properties, like extreme corrosion resistance and low degradation as well as
biocompatibility are expected. Although increasing development activities have
led to system solutions using composite materials, the use of especially
innovative systems, particularly in the area of polymers, has not been realised.
The reason for this is insufficient process stability and reliability, combined
with production and processing problems and inadequate economic efficiency.
Generally, the following are the requirements for reinforcement: low density,
compatibility with polymer composite, chemical compatibility, thermal
stability, high compression and tensile strength, economic efficiency. Most of
the previous work is focused on nano-zinc oxide, nanosilica, carbon nanotube
23
(CNT), graphene, aluminum trihydroxide (ATH). Silicon Carbide (SiC) can be
used as reinforcement due to Low Density, High Strength, Low thermal
expansion, High thermal conductivity, low reactivity as well as the robustness
that make this possible to be used in structural applications. Silicon Carbide also
cost effective compared to other reinforcements like Boron Carbide and the
result being a reasonably priced final product.
PMMA-SiC alloy is not yet to be tried as polymer composite material. This one
is easy to fabricate by means of Injection moulding or Hand Layup process due
to it is better casting qualities. In particle reinforced composites, the properties
of the PMMA composites was observed to depend on reinforcement type,
reinforcement particle size, nature of interface, volume fraction of
reinforcement. Silicon Carbide (SiC) can be used as reinforcement due to Low
Density, High Strength, Low thermal expansion, High thermal conductivity,
24
low reactivity and also SiC is cost effective when compared to the similar
property ceramic like Boron Carbide.
Leslie Banks-Sills et.al (2016) works summarises that Carboxylated CNTs were
further functionalized by the grafting from (GF) and the grafting to (GT)
methods. The effect of these functionalization methods on the CNTs is
evaluated through measurement of effective mechanical properties of a
25
composite containing them, as well as, through a comparison to a previous
investigation, in which non-functionalized (NF) CNTs were employed. it was
seen that the addition of a weight percent higher than 3 of CNTs to a PMMA
matrix increases the elastic modulus of the composite. It was shown that
functionalization of the CNTs prior to their introduction into the matrix
decreases the weight percent of CNTs needed to produce the same increase in
the elastic modulus for non-functionalized CNTs. Low CNT content, both
functionalized and non-functionalized, may cause a decrease in the elastic
modulus or produce a similar value as that of the matrix.
He Runqin et.al (2017), from the studies of the tensile properties, concluded that
the optimum fibre loading was at 20 vol% for CNT/PMMA composite. The
flexural strength of the composites increases with increasing TiO 2 content in the
CNT/PMMA composite. The results show that the addition of TiO 2 helps to
improve the fibre–matrix adhesion leading to higher flexural properties.
Appropriate amount of TiO2 arrive the high-impact strength for the 20 vol %
CNT/PMMA composite. It is observed that addition of CNT and TiO 2 seems to
be beneficial in increasing mechanical strength via increasing the interface
dispersed phase.
27
utilized in high frequency alternating currents (AC) or direct current (DC)
applications.
Garima Mittal et.al (2016), found from the FTIR data that the silane moieties
were attached onto the hBN particles after surface treatment. From FE-SEM and
HR-TEM images, it was observed that multilayer stacking was reduced after
functionalization, and the TGA-DSC curve also validated the attachment of the
silane moieties. Additionally,the thermal and tribological properties of the
composites were compared. It was found that after silanization, the interactions
between hBN and the polymer matrix increased, yielding more homogeneous
dispersion into the polymer matrix, giving rise to the superior thermal and
tribological properties of PMMA/PI/hBN composites.
28
Jialiang Wang et.al (2012) have demonstrated an efficient approach to
covalently grafting PMMA onto the GP sheets. GP was obtained by direct
exfoliation of graphite in NMP and the polymerization was carried out in the
well-dispersed GP solution. Various methods were used to characterize the
PMMA functionalized GP, Compared with other functionalized GO or RGO,
the obtained GPMMA has a perfect structure with fewer defects which enables
the excellent reinforcement to the composites. Furthermore, GPMMA is well-
dispersed in organic solvents and this facilitates the preparation of a variety of
composites. With the addition of only 0.5 wt% GPMMA, the resulting
PMMA/GPMMA composite film exhibits a prominent enhancement of
mechanical properties, 151% and 115% increases in Young’s modulus and
tensile strength (relative to the pure PMMA film), respectively. Moreover, the
thermal stability is also improved due to the strong interfacial adhesion and
good dispersion in the PMMA matrix.
Jun-long Wang et.al (2009) et.al work summarises that the CE can be modified
by CTC-IPN technology. The mechanical properties of the modified CE are
better than those of pure CE. When the weight ratio of CE/PMMA was 80/20,
the maximum values of the mechanical properties occurred. The impact strength
was enhanced by 2.37 times that of pure CE and the flexural strength increased
by 1.31 times, respectively. SiO2 can improve the loading ability of the
polymer. Compared with the mechanical properties of IPN without SiO 2, the
impact strength of IPN was increased by 29.96% and the flexural strength by
20.05% after nanometer SiO2 was added.
A. Akinci et.al (2013) drawn conclusions from their study that Increase in the
applied loads, sliding speeds and increase in ZrO 2 filler content in the sliding
tests resulted to increase in coefficient of friction of the pure PMMA and ZrO 2
filled PMMA composites. Wear rates of ZrO 2 filled PMMA composites
decrease with increase in ZrO2 content up to 30%wt and increase in the applied
29
loads and sliding speeds. The more the ZrO2 contents of the PMMA + ZrO2
composite, the lower the wear rate resulted. ZrO2 filled PMMA composites
show that the worn surface morphologies of the 10% ZrO 2 and 30% ZrO2
PMMA composites were smooth and include some tiny abrasive grooves.
Increase in the ZrO2 content cause to increase in the smoothness of the worn
surfaces.
Poomali et.al (2008) concluded that a marginal reduction in tensile strength and
tensile modulus and significant improvement in percentage elongation at break
was noticed with an increase in the TPU content in the blends. The lowest wear
volume loss is obtained for neat PMMA and the highest wear volume is for the
80/20 PMMA/TPU blend. Better correlation between selected mechanical
properties and wear volume is obtained for neat PMMA and 95/5 PMMA/TPU
blend. Even though TPU is the best wear resistance material, inclusion of this
polymer with PMMA by blending is not beneficial for improved abrasion
resistance. SEM micrographs of TPU-filled PMMA blends showed deep
furrows, wider cracks and more debris during the abrasion process.
30
2.3 AIM OF THE PRESENT WORK:
The following objectives were identified for present work, after extensive
literature survey:
3. To cut various sizes of ASTM Standard specimen from the fabricated plate
by using Water Jet Machining (WJM) process.
31
CHAPTER 3
MATERIAL SELECTION
Physical principles are methods of changing a material that are learned through
material science techniques. Using material science physical principles we can
change material properties. Three common physical principles we can use for
functional material strengthening are densification, composites, and alloying.
There many manufacturing techniques used to strengthen and form materials as
well.
Densification is the most common and necessary way to strengthen any
material. In general, this increases the tensile strength by reducing the porosity
of the material.
The standard composite rule of mixtures is when the standard matrix is
soft/pliable and the reinforcing material is tensile strong. One the major reasons
for the prevalent use of composite materials in construction is the adaptability of
the composite to many kinds of applications. The selection of mixture
proportions can be aimed to achieve optimum mechanical behavior of the
harden product. Selection can result in the change of the strength, consistency,
density, appearance, and durability.
32
properties make them desirable for very specific applications that involve
extreme temperatures, high voltages, or high friction/compressive loads. The
vast majorities of these materials are based upon the nitrides, Carbides, and
oxides of different elements and must be produced with very specialized
equipment.
This tool provides a general overview of the properties of the most common
technical ceramics. Because technical ceramics are used in such a wide variety
of applications, it is useful to understand the relative properties of each material.
If you require more in-depth information, please refer to the relevant material
page where you will find detailed engineering properties.
Since the properties of Silicon Carbide over other ceramics are so good that we
chose Silicon Carbide as one of the material of our composite.
Key strength of SiC over other ceramics:
Low density
High strength
Low thermal expansion
High thermal conductivity
High hardness
High elastic modulus
Excellent thermal shock resistance
Superior chemical inertness
33
The below table lists the different properties of ceramics:
34
Carbide is either a fine powder or a bonded mass that requires crushing and
milling to produce a usable feedstock.
36
(2,910 °F) and 2,500 °C (4,530 °F). Fine SiO2 particles in plant material (e.g.
rice husks) can be converted to SiC by heating in the excess carbon from the
organic material. The silica fume, which is a byproduct of producing Silicon
metal and ferroSilicon alloys, also can be converted to SiC by heating with
graphite at 1,500 °C (2,730 °F).
The material formed in the Acheson furnace varies in purity, according to its
distance from the graphite resistor heat source. Colorless, pale yellow and green
crystals have the highest purity and are found closest to the resistor. The color
changes to blue and black at greater distance from the resistor, and these darker
crystals are less pure. Nitrogen and aluminium are common impurities, and they
affect the electrical conductivity of SiC.
Pure Silicon Carbide can be made by the Lely process, in which SiC powder is
sublimated into high-temperature species of Silicon, carbon, Silicon diCarbide
(SiC2), and diSilicon Carbide (Si2C) in an argon gas ambient at 2500 °C and
37
redeposited into flake-like single crystals, sized up to 2×2 cm, at a slightly
colder substrate. This process yields high-quality single crystals, mostly of 6H-
SiC phase (because of high growth temperature). A modified Lely process
involving induction heating in graphite crucibles yields even larger single
crystals of 4 inches (10 cm) in diameter, having a section 81 times larger
compared to the conventional Lely process. Cubic SiC is usually grown by the
more expensive process of chemical vapor deposition (CVD). Homoepitaxial
and heteroepitaxial SiC layers can be grown employing both gas and liquid
phase approaches. Pure Silicon Carbide can also be prepared by the thermal
decomposition of a polymer, poly(methylsilyne), under an inert atmosphere at
low temperatures. Relative to the CVD process, the pyrolysis method is
advantageous because the polymer can be formed into various shapes prior to
thermalization into the ceramic.
Silicon Carbide exists in about 250 crystalline forms. The polymorphism of SiC
is characterized by a large family of similar crystalline structures called
polytypes. They are variations of the same chemical compound that are identical
in two dimensions and differ in the third. Thus, they can be viewed as layers
38
stacked in a certain sequence. Alpha Silicon Carbide (α-SiC) is the most
commonly encountered polymorph; it is formed at temperatures greater than
1700 °C and has a hexagonal crystal structure (similar to Wurtzite). The beta
modification (β-SiC), with a zinc blende crystal structure (similar to diamond),
is formed at temperatures below 1700 °C. Until recently, the beta form has had
relatively few commercial uses, although there is now increasing interest in its
use as a support for heterogeneous catalysts, owing to its higher surface area
compared to the alpha form.
39
Pure SiC is colorless. The brown to black color of the industrial product results
from iron impurities. The rainbow-like luster of the crystals is caused by
a passivation layer of Silicon dioxide that forms on the surface.
40
process begins by reviewing the plastic material data sheets generally provided
by the material suppliers. A misinterpretation of the data sheets is one of the
most common reasons for selecting and specifying the wrong material, for a
given application. First it is important to understand the purpose of a data sheet.
Data sheets are useful only for comparing property values of different plastic
materials such as the tensile strength of nylon versus polycarbonate or the
impact strength of polystyrene versus ABS. Data sheets should be used for
initial screenings of various materials. For example, if a designer is looking for
a material that is strong and tough, he may start out by selecting materials
whose reported values are higher than 7,000 psi tensile strength and impact
strength values of better than 1.0 ft F lb/in and eliminating material such as
general purpose polystyrene, polypropylene, and polyethylene. Data sheets are
never meant to be used for engineering design and final or ultimate material
selections. First, the reported data is generally derived from the short term tests.
Short term tests, as the name suggests, are the tests conducted without
consideration of time, and the values derived are instantaneous. Tensile test,
izod impact test, and Heat Distortion Temperature, are the examples of such
short term tests. Data reported on data sheets are also derived from single point
measurements. These tests do not take into account the effect of time,
temperature, environment, and chemicals, etc. A single number representing one
point on a stress-strain curve cannot begin to convey plastics’ behavior over a
range of conditions. The standardized tests used to measure data sheet
properties contain data measured in a laboratory under ideal conditions (as
specified by ASTM or ISO standards) on standardized test specimens that bear
little resemblance to the geometry of real-world parts. These tests likewise take
place at temperatures, stress and strain rates that rarely corresponds to the real-
world conditions.
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The proper use of multi-point data for selecting the most appropriate plastic
materials for the applications cannot be over emphasized. This point is well
illustrated in a classic example of misinterpretation of published test data and
the true meaning and usefulness of Heat Distortion Temperature (HDT) values.
The Heat Distortion Temperature test is a short-term test conducted using
standard test bars and laboratory conditions. The temperature values derived
from this test for a particular plastic material is simply an indication of the
temperature at which the test bar shall deform .010 in. under a specified load.
The reported values are further distorted by factors such as residual stresses in
the test bars, amount of load, and specimen thickness. This reported value is of
limited practical importance and should not be used to select materials for
applications requiring continuous exposure at elevated temperatures.
Continuous use temperature data such as UL temperature index is a better
indication of how plastic materials will perform for extended period at elevated
temperatures. Key considerations are mechanical properties:
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3.2.1 Comparison of PMMA
43
3.2.2 Poly(methyl methacrylate)
Although not a type of familiar silica-based glass, the substance, like many
thermoplastics, is often technically classified as a type of glass (in that it is a non-
crystalline vitreous substance) hence its occasional historical designation as acrylic
glass. Chemically, it is the synthetic polymer of methyl methacrylate. PMMA is an
economical alternative to polycarbonate (PC) when tensile strength, flexural
strength, transparency, polishability, and UV tolerance are more important
than impact strength, chemical resistance and heat resistance. Additionally,
PMMA does not contain the potentially harmful bisphenol-A subunits found in
polycarbonate. It is often preferred because of its moderate properties, easy
handling and processing, and low cost. Non-modified PMMA behaves in a brittle
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manner when under load, especially under an impact force, and is more prone to
scratching than conventional inorganic glass, but modified PMMA is sometimes
able to achieve high scratch and impact resistance.
Transparent
Good rigidity
Dimensionally stable
(when modified)
The glass transition temperature (Tg) of atactic PMMA is 105 °C (221 °F).
The Tg values of commercial grades of PMMA range from 85 to 165 °C (185 to
45
329 °F); the range is so wide because of the vast number of commercial
compositions which are copolymers with co-monomers other than methyl
methacrylate. PMMA is thus an organic glass at room temperature; i.e., it is below
its Tg. The forming temperature starts at the glass transition temperature and goes
up from there. All common Moulding processes may be used, including injection
Moulding, compression Moulding, and extrusion. The highest quality PMMA
sheets are produced by cell casting, but in this case, the polymerization and
Moulding steps occur concurrently. The strength of the material is higher than
Moulding grades owing to its extremely high molecular mass. Rubber
toughening has been used to increase the toughness of PMMA to overcome its
brittle behavior.
Laser cutting may be used to form intricate designs from PMMA sheets. PMMA
vaporizes to gaseous compounds (including its monomers) upon laser cutting, so a
very clean cut is made, and cutting is performed very easily. However, the pulsed
lasercutting introduces high internal stresses along the cut edge, which on exposure
to solvents produce undesirable "stress-crazing" at the cut edge and several
millimetres deep. Even ammonium-based glass-cleaner and almost everything
short of soap-and-water produces similar undesirable crazing, sometimes over the
entire surface of the cut parts, at great distances from the stressed edge. Annealing
the PMMA sheet/parts is therefore an obligatory post-processing step when
intending to chemically bond laser cut parts together.
In the majority of applications, it will not shatter. Rather, it breaks into large dull
46
pieces. Since PMMA is softer and more easily scratched than glass, scratch-
resistant coatings are often added to PMMA sheets to protect it (as well as possible
other functions).
PMMA swells and dissolves in many organic solvents; it also has poor resistance
to many other chemicals due to its easily hydrolyzed ester groups. Nevertheless, its
environmental stability is superior to most other plastics such as polystyrene and
47
polyethylene, and PMMA is therefore often the material of choice for outdoor
applications.
Being transparent and durable, PMMA is a versatile material and has been
used in a wide range of fields and applications such as rear-lights.
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CHAPTER 4
FABRICATION OF LAMINATES
Laminates are fabricated in the various methods. These methods has different
steps and they involve usage of additives and resins to involve uniform
formation and even distribution of composite (PMMA and SIC). The various
methods used in the process of laminates moulding are
Injection moulding
Compression moulding
Hand Lay-up
Paper clip mould opened in moulding machine; the nozzle is visible at right.
Injection moulding machines consist of a material hopper, an injection ram or
screw-type plunger, and a heating unit. Also known as platens, they hold the
moulds in which the components are shaped. Presses are rated by tonnage,
which expresses the amount of clamping force that the machine can exert. This
force keeps the mould closed during the injection process. Tonnage can vary
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from less than 5 tons to over 9,000 tons, with the higher figures used in
comparatively few manufacturing operations.
With injection moulding, granular plastic is fed by a forced ram from a hopper
into a heated barrel. As the granules are slowly moved forward by a screw-type
plunger, the plastic is forced into a heated chamber, where it is melted. As the
plunger advances, the melted plastic is forced through a nozzle that rests against
the mould, allowing it to enter the mould cavity through a gate and runner
system. The mould remains cold so the plastic solidifies almost as soon as the
mould is filled.
4.1.3 Applications
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polyethylene, and polystyrene are thermoplastic. Until comparatively recently,
plastic springs were not possible, but advances in polymer properties make them
now quite practical. Applications include buckles for anchoring and
disconnecting the outdoor-equipment webbing.
Heat and pressure is applied as per the requirement of composite for a definite
period of time. The material placed in between the moulding plates flows due to
52
application of pressure and heat and acquires the shape of the mould cavity with
high dimensional accuracy which depends upon mould design. Curing of the
composite may carried out either at room temperature or at some elevated
temperature. After curing, mould is opened and composite product is removed
for further processing. In principle, a compression moulding machine is a kind
of press which is oriented vertically with two moulding halves (top and bottom
halves). Generally, hydraulic mechanism is used for pressure application in
compression moulding.
53
from the composite system. If temperature is too high, properties of fibres and
matrix may get changed.
If temperature is low than desired, fibres may not get properly wetted due to
high viscosity of polymers especially for thermoplastics. If time of application
of these factors (pressure and temperature) is not sufficient (high or low), it may
cause any of defects associated with insufficient pressure or temperature. The
other manufacturing factors such as mould wall heating, closing rate of two
matched plates of the plates and de-moulding time also affect the production
process.
Some of the materials which are commonly used in the compression moulding
are
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4.2.2 Applications
Typical products include automobile panels, roof, life gates, battery trays,
fenders, hoods, bumpers, spoilers, air deflectors, furniture kitchen bowls and
trays, dinnerware, buttons, large containers, recreational vehicle body panels,
medical equipment (ultrasound equipment).
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4.3 HAND LAY-UP
4.3.1 Mould
The mould will have the shape of the product. In order to have a glossy or
texture finish on the surface of the product, the mould surface also should have
the respective finish. If the outer surface of the product to be smooth, the
product is made inside a female mould. Likewise, if the inner side has to be
smooth, the moulding is done over a male mould. The mould should be free
from defects, since the imprint of any defect will be formed on the product.
Release
Since, the resins used are highly adhesive, the product may get stuck to the
mould. So, a proper releasing mechanism should be incorporated. The release of
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the product can be affected by the use of a release layer of wax or polyvinyl
alcohol (PVA). By using a thin film like polyester film (Mylar). Since, the
Mylar sheet has to be fit into the mould profile, this method is not used for
complex shapes.
The gel coat gives the required finish of the product. It is usually a thin layer of
resin about mm thickness applied on the outer surface of the product. The
colour is obtained by adding appropriate pigments to the resin. The gel coat
forms a protective layer that protects the glass fibre getting in contact with water
and chemicals. If the gel coat is too thin, the fibre pattern will become visible. If
it is too thick, crazing and star crack can appear on the gel coat.
A surface mat layer will be placed beneath the gel coat layer. The fibres of the
mat will not give high strength like reinforcement fibres, but the mat provides
crack resistance and impact strength to the resin rich layer. It is an optional layer
used only in specific cases.
The glass fibre layer wetted with resin is laid up one after another to the
required thickness and this finished material is called the laminate. The laminate
gives the strength and rigidity to the product. Glass fibre in the chopped strand
mat (CSM) is commonly used to get composite products. Woven roving,
unidirectional and bi-directional mats are also used to get high strength
composite products.
The glass fibre laminate provides a rough surface finish. In order to get a
smoother surface, a surface mat layer or resin coat may be applied over.
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For the selection of Hand Lay-up as a fabrication process, the following
conditions should favour:
The surface mat layer must be applied only after the gel coat is cured. Otherwise
the surface finish will be affected. The surface layer can be any one of the
following. Glass fibre surface tissue mat. Polyester woven cloth of fine
thickness Nylon woven cloth of fine thickness A thin layer of resin is applied
over the surface and the mat is wetted with brush. It may also be lightly rolled
with roller to remove the air bubbles.
The lay-up should start as soon as the gel coat layer is cured. The lamination
should satisfy the following requirements:
The fibre layers should be uniformly placed and they should fit correctly
into the contour of the product.
The resin mix can be prepared at least one day ahead so that the entrapment of
air bubbles escape before the lay-up begins. The mix consists of the resin,
accelerator, fillers, and additives if any. The addition of accelerator to resin will
not cause any cross linking until catalyst is added. The mixing can be done by
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either manually using a paddle or by using an air operated mixer. Vigorous
stirring can cause entrapment of air bubbles therefore; mixing should be done at
a very low rpm. The container in which resin mix is stored may be closed air
tight to minimize the vaporization and loss of styrene.
The required number layers to obtain the thickness can be determined by taking
into account the mat density and the glass-to-resin ratio by weight. The
following points must be taken into account while preparing the mat:
Brushes - to apply resin for both gel coat application and for lamination.
Rollers - to remove the air bubbles and also for applying resin.
Long rollers are used to consolidate large areas but short rollers are used for
corners and curved surfaces. Mugs and small bowls - for taking the resin mix
for lay-up.
2) Solvents:
Solvents are required for cleaning the rollers and brushes during or after the lay-
up sequence is over. Acetone or Nitrocellulose thinner can be used as solvents.
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4.3.4 Lamination Procedure
In the process of lamination a thin layer of resin is applied on the gel coat layer.
Then, a chopped strand mat is placed over it. The resin is again applied over the
mat by using brush to wet the mat. By using the roller the air bubbles are
removed.
After the first layer is laid up, subsequent layers are laid in a similar manner.
More than 4 layers of resin and glass mat should not be applied without
allowing the resin to cure at a time. When WRM is laid up, CSM is used in
between in order to increase the inter-laminar shear strength.
The lay-up procedure for WRM and CSM are identical except that the resin
used for WRM is half the quantity of that is needed for CSM. Curing of Resin:
The curing of resin process undergoes through four stages:
1) Gelation Stage: It is the stage at which the resin becomes tack free and
unworkable. It depends on the percentage of catalyst and accelerator
added. Normally, it takes 15 to 30 minutes to gel.
2) Green Stage: This is the stage at which the resin resembles to hard cheese
which when pressed with the thumb it breaks up. The resin is considered
to be set but not cured.
3) Cured Stage: It is the stage at which more than 90% of the cure is
completed. The product can be released from the mould after this stage.
4) Fully Cured Stage: It is the stage at which the physical properties of the
moulding are developed. Normally, it takes 5 to 10 days.
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No costly machinery is required.
Fine Colour and texture finish can be obtained by this Hand Lay-up
method.
Plates created using hand layup method is to be cut into required “ASME
STANDARD SHAPES” so that it can be used for various testing process. In our
project the cutting of plates is done by “Water Jet Cutting” or “Water Jet
Machining” method.
The above ASME STANDARD specimen is created using water jet cutting
machining using CNC operated water jet machine. Water Jet Machining (WJM)
also called as water jet cutting is a non-traditional machining process in which
high velocity jet of water is used to remove materials from the surface of the
work piece. WJM can be used to cut softer materials like plastic, rubber or
wood. In order to cut harder materials like metals or granite, an abrasive
material is mixed in the water.
4.3.7.1 Operation
All water jets follow the same principle of using high pressure water focused
into a beam by a nozzle. Most machines accomplish this by first running the
water through a high pressure pump. There are two types of pumps used to
create this high pressure; an intensifier pump and a direct drive or crankshaft
pump. A direct drive pump works much like a car engine, forcing water through
high pressure tubing using plungers attached to a crankshaft. An intensifier
pump creates pressure by using hydraulic oil to move a piston forcing the water
through a tiny hole. The water then travels along the high pressure tubing to the
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nozzle of the water jet. In the nozzle, the water is focused into a thin beam by a
jewel orifice. This beam of water is ejected from the nozzle, cutting through the
material by spraying it with the jet of high-speed water. The process is the same
for abrasive water jets until the water reaches the nozzle. Here abrasives such as
garnet and aluminium oxide are fed into the nozzle via an abrasive inlet. The
abrasive then mixes with the water in a mixing tube and is forced out the end at
high pressure.
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CHAPTER 5
After fabrication of the laminate of (PMMA and SIC), the plate is cut into
standard specimen according to ASME standards through water jet cutting
method. Then the specimens are subjected to following four testing which is
performed in micro lab technologies under supervised condition. The end
factors are controlled for the tests and the results are plotted in tables and in
graphs to indicate its results. The tests performed are listed as follows:
Tensile test
Bend test
Flexural test
A tensile test, also known as tension test, is probably the most fundamental type
of mechanical test you can perform on material. Tensile tests are simple,
relatively inexpensive, and fully standardized. By pulling on something, you
will very quickly determine how the material will react to forces being applied
in tension. As the material is being pulled, you will find its strength along with
how much it will elongate.
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It helps in determine the maximum force that the material can withstand without
failure
Bend tests deform the test material at the midpoint causing a concave surface or
a bend to form without the occurrence of fracture and are typically performed to
determine the ductility or resistance to fracture by deforming the sample into a
specific shape. The test sample is loaded in a way that creates a concave surface
at the midpoint with a specified radius of curvature.
The main purpose of the Bend testing is to determine the ductility, bend
strength, fracture strength and resistance to fracture of the specimen. It is used
to determine the characteristics of a material which it will fail under pressure.
A flexural specimen simply rests on two supports and is loaded at one or two
points along its length, making the test very easy to perform. Thus this test is
involved with ceramic-matrix composites and bulk ceramics.
In a flexural test, the stress state is neither pure (it varies from tension on one
surface to compression on the other, with shear present as well), nor uniform (it
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varies along the length of the specimen). So a composite material is best suited
to this testing.
To investigate the effect of the ratio of the support-span length to thickness l/t
on impact characteristics for both unidirectional. Charpy test rig were
conducted in order to identify key parameters influencing the impact damage
resistance of composite structures.
The various analysis and testings were carried out to determine the tensile
strength, bend test, flexural test and charpy impact test. These values are shown
in the report given below:
66
67
68
The reports yielded information pertaining to tensile test, wear test, flexural test
and charpy impact test. These result are presented in an chart format for better
understanding: (values are in MPa)
TENSILE TEST(PMMA+SiC+GFRP)
50
45
40
35
30
25
20
15
10
5
0
SiC 5% SiC 10%
69
70
Based on the results obtained, the following are the conclusions reaped, when
PMMA is reinforced with Glass Fibre Mat and varying percentages of Silicon
carbide:
Bend test which is performed to access the ductility and soundness of the
polymer, resulted such that, on increasing the Silicon Carbide percent, the
specimen were susceptible to improved ductility.
The results from impact test indicated that, specimens with higher
concentration of Silicon Carbide were able to withstand higher rates of
loading and thereby 9+proving its improved service life.
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On comparing these properties with pure PMMA, it was signified that the
tensile strength of reinforced polymers were deprived. This on the contrary
improved the hardness properties of the specimen, thereby levitating the surface
hardness.
With improved surface hardness properties, the specimen could bear extended
scratch exposures. Silicon Carbide, on reinforcing with PMMA showcased an
improved melting range, therefore instituting its application on fields
demanding polymers sustenance on higher temperatures.
72
73
74
75
The morphology of different composition of polymer matrix composite are
observed and analyzed in Scanning Electron Microscope(SEM) are shown:
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CHAPTER 6
COST ANALYSIS
3. GFRP 6 sheets
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6.2 COST ANALYSIS
1. PMMA 210
3. GFRP 600
5. TOTAL 2370
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6.2.2 Machining Cost
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CHAPTER 7
This holds good for our conclusion. PMMA reinforced with 10% Silicon
Carbide exhibited a tensile strength of 43MPa. There is a converse
relationship between tensile strength and hardness, which factualizes that
Tensile strength and Hardness are inversely proportional.
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CHAPTER 8
CONCLUSION
Polymers, which have been lately sensationalized for its alluring properties, has
an potential to attract global dependence. Metals conventionally used pose
concerns as they can’t be relied indefinitely due to this present exhaustion rates.
Polymers on the other hand can be synthesized by polymerization lending in
inarticulate ways of reliance. Polymer parts are lighter and therefore provide
immense advantages over metals by offering lower lifetime freight costs for
equipment that is regularly transported or handled over the product’s lifetime.
The low frictional properties provide for less wear as well. The lower wear rates
allow for less maintenance-related downtime. Not only are polymers lighter, but
they’re also less expensive than many raw metal materials used for parts.
Polymers are produced in faster cycles than metals which helps keep
manufacturing costs down as well. Corrosion due to moisture or even dissimilar
metals in close contact is also a major concern with metal components, but
polymer and composite materials are impervious to chemicals. Polymers and
composites are both thermally and electrically insulating. Metallic components
require special secondary processing and coating in order to achieve any sort of
insulating properties. These components are also naturally corrosion resistant
and experience no galvanic effects in a dissimilar metal scenario that require
sheathing. All these advantages make polymers dominate the throne of metals.
The growth in the fields of composite makes it imminent that future is certainly
“polymer reliant”. To abreast this, constant evolvements are being done to
further enhance the properties of polymers, by either synthesizing novel
polymers or reinforcing with characteristic materials. Our research, on
reinforcing PMMA with SiC has shown valuable outcomes, thereby enlisting
this composite as a viable alternative.
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REFERENCES
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