Composite materials are composed of two or more distinct materials that have improved properties over the individual materials. The document discusses various types of composite materials including particle-reinforced, fiber-reinforced, and structural composites. It describes the matrix and dispersed phases, and how their interaction leads to improved properties. Different classifications of composites are also covered based on the matrix material and reinforcement structure. A wide range of applications are mentioned stemming from the composites' high strength, stiffness, and low density properties.

1. 1.Definition
•A broad definition of composite is: Two or more chemically distinct
materials which when combined have improved properties over the
individual materials.
•The constituents retain their identities in the
composite; that is, they do not dissolve or otherwise merge completely
into each other, although they act in concert.

2. 2.Composite material is a material composed of two or more
distinct phases (matrix phase and dispersed phase) and having bulk properties
significantly different form those of any of the constituents.
Matrix phase
The primary phase, having a continuous character, is called matrix. Matrix is
usually more ductile and less hard phase. It holds the dispersed phase and
shares a load with it.
Dispersed (reinforcing) phase
The second phase (or phases) is embedded in the matrix in a discontinuous
form. This secondary phase is called dispersed phase. Dispersed phase is
usually stronger than the matrix, therefore it is sometimes called reinforcing
phase.
Many of common materials (metal alloys, doped Ceramics and Polymers mixed
with additives) also have a small amount of dispersed phases in their
structures, however they are not considered as composite materials since
their properties are similar to those of their base constituents (physical
properties of steel are similar to those of pure iron).
There are two classification systems of composite materials. One of them is
based on the matrix material (metal, ceramic, polymer) and the second is
based on the reinforcing material structure:

3. 2.BASIC CLASSIFICATION

4. 3.ADVANTAGES OF COMPOSITE.
• Reason to use composite material:-
I. Higher specific strength than metals, non-metals and even alloys.
II. Lower specific gravity in general.
III. Improved stiffness of material.
IV. Composite maintain their weight even at high temperatures.
V. Toughness is improved.
VI. Fabrication or production is cheaper.
VII. Creep and fatigue strength is better.
VIII. Controlled Electrical conductivity is possible.
IX. Corrosion and oxidation resistance.

5. Advantages of Composites
•Light in weight
•Strength-to-weight and Stiffness-to-weight are greater
than steel or aluminum
•Fatigue properties are better than common engineering
metals •Composites cannot corrode like steel
•Possible to achieve combinations of properties not
attainable with metals, ceramics, or polymers alone
Composites are one of the most widely used materials
because of their adaptability to different situations and
the relative ease of combination with other materials to
serve specific purposes and exhibit desirable properties.
• The main advantages of composite materials are their
high strength and stiffness, combined with low density,
when compared with bulk materials.

6. Advantages of Composites
• Composites are engineered materials. We can
engineer them specifically to meet our needs on a
case‐to‐case basis. In general, following properties
can be improved by using composite materials.
– Strength Electrical conductivity
– Modulus Thermal conductivity
– Weight Behavior at extreme temps.
– Fatigue Acoustical insulation
– Vibration damping Aesthetics
– Resistance to wear Resistance to corrosion

10. 4.GENERAL APPLICATIONS

11. 5.FIBRES APPLICATIONS IN DETAIL
• In heavy transport vehicles, the composites are used in processing of component parts with
cost-effectiveness
• Most of the thermoplastics are combined with reinforcing fibers in various proportions. Several
methods are used to produce vehicle parts from thermo plastics.
•Some complicated parts of light commercial vehicles, which need casting, may be compression
moulded from composites of the sheet or bulk variety.
•A reinforced-plastic composite can be used for such light vehicle parts.
•Sheet metal body of automobile is moulded in matched moulding dies with fiber glass or
rovings as reinforcements.
•Commercial aircraft applications are the most important uses of composites.
•Glass reinforced composites can be used.
•Carbon Fiber : Applications: Aircraft body, cycle body frame, sports equipments
•Glass filaments have been used in space vehicles
Matrix: Epoxy
• Polyester
• Vinyl Ester
• Nylon
Reinforcement
• Carbon Fiber
• Aramid
• Aluminum
• Ultra-High Molecular Weight Polyethylene (UHMWPE)

12. Fiberglass applications :Fiberglass : Applications - Storage Tanks, Bathtubs
, Piping Systems, Sports Masks & Helmets
Glass fiber reinforced plastic, used for containers, is also used for paneling in rail cars.
Fiberglass has been the flexible insulation material of choice for these vehicles.
Matrix:
• Epoxy
• Polyester
• Vinyl Ester
• Nylon
Glass fibers made of:
- Silica or Silicate
- Oxides of Calcium
- Magnesium
-Boron
-Plastic polymers in Army Applications : Bullet Proof Vest, Bulletproof Glass
A bulletproof vest consists of a panel, a vestshaped
sheet of advanced plastics polymers that is
composed of many layers of either Kevlar, Spectra
Shield

13. Fiber-reinforced plastic is a composite material can be used for Construction
Applications
made of a polymer matrix reinforced with fibres.
Reinforcement material :
• Glass fibers
• Natural fibers
• Carbon fibers
Particulate material :
• Sand, talc and other fillers
• Color chips
• Recycled glass
The composite materials used in aircraft industry are generally reinforced fibres or
filaments embedded in a resin matrix. The most common fibres are carbon, aramid,
glass and their hybrid.

14. 5.APPLICATIONS OF MATRIX MATERIALS IN DETAIL
1.PMC’S
2.MMC’S
3.CMC’S

18. CMC materials overcome the major disadvantages of conventional
technical ceramics, namely brittle failure and low fracture
toughness, and limited thermal shock resistance. Therefore, their
applications are in fields requiring reliability at high-temperatures
(beyond the capability of metals) and resistance to corrosion and
wear.[22] These include:
Heat shield systems for space vehicles, which are needed during
the re-entry phase, where high temperatures, thermal
shock conditions and heavy vibration loads take place.
Components for high-temperature gas turbines such as combustion
chambers, stator vanes and turbine blades.
Components for burners, flame holders, and hot gas ducts, where
the use of oxide CMCs has found its way.
Brake disks and brake system components, which experience
extreme thermal shock (greater than throwing a glowing part of any
material into water).
Components for slide bearings under heavy loads requiring high
corrosion and wear resistance.

19. 6.PROPERTIES OF COMPOSITE MATERIALS

20. 6.IMPROVED PROPERTIES OF COMPOSITES

21. Composite material is a material composed of two or more
distinct phases (matrix phase and dispersed phase) and having bulk properties
significantly different form those of any of the constituents.
Matrix phase
The primary phase, having a continuous character, is called matrix. Matrix is
usually more ductile and less hard phase. It holds the dispersed phase and
shares a load with it.
Dispersed (reinforcing) phase
The second phase (or phases) is embedded in the matrix in a discontinuous
form. This secondary phase is called dispersed phase. Dispersed phase is
usually stronger than the matrix, therefore it is sometimes called reinforcing
phase.
Many of common materials (metal alloys, doped Ceramics and Polymers mixed
with additives) also have a small amount of dispersed phases in their
structures, however they are not considered as composite materials since
their properties are similar to those of their base constituents (physical
properties of steel are similar to those of pure iron).
There are two classification systems of composite materials. One of them is
based on the matrix material (metal, ceramic, polymer) and the second is
based on the reinforcing material structure:
7.CLASSIFICATION OF COMPOSITE MATERIALS IN DETAIL

22. Classification of composites I
(based on matrix material)
Metal Matrix Composites (MMC)
Metal Matrix Composites are composed of a metallic matrix
(aluminum, magnesium, iron, cobalt, copper) and a dispersed
ceramic (oxides, carbides) or metallic (lead, tungsten,
molybdenum) phase.
Ceramic Matrix Composites (CMC)
Ceramic Matrix Composites are composed of a ceramic matrix and
embedded fibers of other ceramic material (dispersed phase).
Polymer Matrix Composites (PMC)
Polymer Matrix Composites are composed of a matrix
from thermoset (Unsaturated Polyester (UP), Epoxiy (EP))
or thermoplastic (Polycarbonate (PC), Polyvinylchloride, Nylon,
Polysterene) and embedded glass, carbon, steel or Kevlar fibers
(dispersed phase).
7.CLASSIFICATION OF COMPOSITE MATERIALS BASED ON MATRIX MATERIALS

23. Classification of composite materials II
(based on reinforcing material structure)
A Particulate Composites
Particulate Composites consist of a matrix reinforced by a dispersed phase in
form of particles.
Composites with random orientation of particles.
Composites with preferred orientation of particles. Dispersed phase of these
materials consists of two-dimensional flat platelets (flakes), laid parallel to
each other.
B Fibrous Composites
Short-fiber reinforced composites. Short-fiber reinforced composites consist
of a matrix reinforced by a dispersed phase in form of discontinuous fibers
(length < 100*diameter).
Composites with random orientation of fibers.
Composites with preferred orientation of fibers.
C LAMINAR Composites A laminar composite is composed of two-
dimensional sheets or panels that have a preferred high-strength direction
such as is found in wood and continuous and aligned fiber-reinforced plastics.
The layers are stacked and subsequently cemented together such that the
orientation of the high-strength direction varies with each successive layer
8.CLASSIFICATION OF COMPOSITES BASED ON REINFORCEMENTS

24. (Figure 16.16). For example, adjacent wood sheets in plywood are
aligned with the grain direction at right angles to each other. Laminations may also
be constructed using fabric material such as cotton, paper, or woven glass fibers
embedded in a plastic matrix. Thus a laminar composite has relatively high strength in
a number of directions in the two-dimensional plane; however, the strength in any
given direction is, of course, lower than it would be if all the fibers were oriented
in that direction.

25. 1) CLASSIFICATION OF COMPOSITES IN DETAIL – BASIC
CLASSIFICATION Many composite materials are composed of just two
phases; one is termed the matrix, which is continuous and surrounds
the other phase, often called the dispersed phase. The properties of
composites are a function of the properties of the constituent
phases, their relative amounts, and the geometry of the dispersed
phase. “Dispersed phase geometry” in this context means the shape of
the particles and the particle size, distribution, and orientation; these
characteristics are represented in Figure 16.1.
One simple scheme for the classification of composite materials is
shown in Figure 16.2, which consists of three main divisions:
particle-reinforced, fiber-reinforced, and structural
composites; also, at least two subdivisions exist for each. The
dispersed phase for particle-reinforced composites is equiaxed (i.e.,
particle dimensions are approximately the same in all directions); for
fiber-reinforced composites, the dispersed phase has the geometry of
a fiber (i.e., a large length-to-diameter ratio). Structural composites are
Combinations of composites and homogeneous materials.

30. 1)Particle-Reinforced Composites
As noted in Figure 16.2, large-particle and dispersion-strengthened composites are
the two subclassifications of particle-reinforced composites. The distinction between
these is based upon reinforcement or strengthening mechanism. The term “large” is
used to indicate that particle–matrix interactions cannot be treated on the atomic or
molecular level; rather, continuum mechanics is used. For most of these composites,
the particulate phase is harder and stiffer than the matrix. These reinforcing particles
tend to restrain movement of the matrix phase in the vicinity of each particle. In
essence, the matrix transfers some of the applied stress to the particles, which bear
a fraction of the load. The degree of reinforcement or mprovement of mechanical
behavior depends on strong bonding at the matrix–particle interface.
For dispersion-strengthened composites, particles are normally much smaller,
with diameters between 0.01 and 0.1 m (10 and 100 nm). Particle–matrix
interactions that lead to strengthening occur on the atomic or molecular level. The
mechanism of strengthening is similar to that for precipitation hardening discussed
in
Section 11.9. Whereas the matrix bears the major portion of an applied load, the
small dispersed particles hinder or impede the motion of dislocations. Thus, plastic
deformation is restricted such that yield and tensile strengths, as well as hardness,
improve.

31. 16.3 DISPERSION-STRENGTHENED COMPOSITES
Metals and metal alloys may be strengthened and hardened by the uniform
dispersion
of several volume percent of fine particles of a very hard and inert material.The
dispersed phase may be metallic or nonmetallic; oxide materials are often
used.Again,
the strengthening mechanism involves interactions between the particles and
dislocations within the matrix, as with precipitation hardening. The dispersion
strengthening effect is not as pronounced as with precipitation hardening;
however, the strengthening is retained at elevated temperatures and for
extended time periods because the dispersed particles are chosen to be
unreactive with the matrix phase.
The most common particle reinforced composite is concrete, which is a
mixture of gravel and sand usually strengthened by addition of small rocks or
sand. Metals are often reinforced with ceramics to increase strength at the
cost of ductility.

33. 2)Fiber-Reinforced Composites
Technologically, the most important composites are those in which the matrix phase
of soft ductile materials is introduced into dispersed phase which is in the form of a
fiber. Design goals of fiber-reinforced composites often include high strength and/or
stiffness on a weight basis. These characteristics are expressed in terms of specific
strength and specific modulus parameters, which correspond, respectively, to the
ratios of tensile strength to specific gravity and modulus of elasticity to specific
gravity
fiber-reinforced composites are subclassified by fiber
length. For short fiber, the fibers are too short to produce a significant improvement
in strength.
On the basis of diameter and character, fibers are grouped into three different
classifications: whiskers, fibers, and wires.
OR FIBRES , PARTICLES AND FLAKES
Materials that are classified as fibers are either polycrystalline or amorphous
and have small diameters; fibrous materials are generally either polymers or
ceramics
(e.g., the polymer aramids, glass, carbon, boron, aluminum oxide, and silicon
carbide).

34. Whiskers are very thin single
crystals that have extremely large length-to-diameter ratios. As a consequence
of their small size, they have a high degree of crystalline perfection and are virtually
flaw free, which accounts for their exceptionally high strengths; they are
among the strongest known materials. In spite of these high strengths, whiskers
are not utilized extensively as a reinforcement medium because they are extremely
expensive. Moreover, it is difficult and often impractical to incorporate
whiskers into a matrix. Whisker materials include graphite, silicon carbide, silicon
nitride, and aluminum oxide
Fine wires have relatively large diameters; typical materials include steel,
molybdenum, and tungsten.Wires are utilized as a radial steel reinforcement in
automobile tires, in filament-wound rocket casings, and in wire-wound high-pressure
hoses.
Particles and Flakes

35. • A second common shape of imbedded phase is
particulate, ranging in size from microscopic to
macroscopic
• Flakes are basically two dimensional - particles - small
flat platelets
• The distribution of particles in the composite matrix is
random, and therefore strength and other properties
of the composite material are usually isotropic
• Strengthening mechanism depends on particle size
Materials for Fibers
• Fiber materials in fiber -reinforced composites:
- Glass – most widely used filament
- Carbon – high elastic modulus
- Boron – very high elastic modulus
- Polymers - Kevlar
- Ceramics – SiC and Al2O3
- Metals - steel
• The most important commercial use of fibers is in
polymer composites

39. Continuous-fiber composites normally have a preferred orientation,
whilediscontinuous fibers generally have a random orientation. ...
typical fibers include glass, aramid, and carbon, which may
be continuous or discontinuous. thecontinuous phase is the matrix, which is a
polymer, metal, or ceramic.

43. 3) Structural Composites
A structural composite is normally composed of both homogeneous and composite
materials, the properties of which depend not only on the properties of the
constituent materials but also on the geometrical design of the various structural
elements. Laminar composites and sandwich panels are two of the most common
structural composites; only a relatively superficial examination is offered here for
them.
16.14 LAMINAR COMPOSITES
A laminar composite is composed of two-dimensional sheets or panels that have a
preferred high-strength direction such as is found in wood and continuous and
aligned fiber-reinforced plastics.The layers are stacked and subsequently cemented
together such that the orientation of the high-strength direction varies with each
successive layer (Figure 16.16). For example, adjacent wood sheets in plywood are
aligned with the grain direction at right angles to each other. Laminations may also
be constructed using fabric material such as cotton, paper, or woven glass fibers
embedded in a plastic matrix. Thus a laminar composite has relatively high strength in
a number of directions in the two-dimensional plane; however, the strength in any
given direction is, of course, lower than it would be if all the fibers were oriented
in that direction. One example of a relatively complex laminated structure is the
modern ski (see the chapter-opening illustration for this chapter).

45. 16.15 SANDWICH PANELS
Sandwich panels, considered to be a class of structural composites, are designed
to
be light-weight beams or panels having relatively high stiffnesses and strengths. A
sandwich panel consists of two outer sheets, or faces, that are separated by and
adhesively
bonded to a thicker core (Figure 16.17). The outer sheets are made of a
relatively stiff and strong material, typically aluminum alloys, fiber-reinforced
plastics,
titanium, steel, or plywood; they impart high stiffness and strength to the
structure,
and must be thick enough to withstand tensile and compressive stresses that
result from loading.The core material is lightweight, and normally has a low
modulus
of elasticity. Core materials typically fall within three categories: rigid polymeric
foams (i.e., phenolics, epoxy, polyurethanes), wood (i.e., balsa wood), and
honeycombs (see below). Sandwich panels are used in a wide variety of
applications including roofs, floors,
and walls of buildings; and, in aerospace and aircraft (i.e., for wings, fuselage, and
tailplane skins).