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COMPOSITES

COMPOSITES. COMPOSITE MATERIALS – INTRODUCTION. Definition: Any combination of two or more different materials at the macroscopic level. OR Two inherently different materials that when combined together produce a material with properties that exceed the constituent materials.

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COMPOSITES

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  1. COMPOSITES Source:

  2. COMPOSITE MATERIALS – INTRODUCTION • Definition: Any combination of two or more different materials at the macroscopic level. OR • Two inherently different materials that when combined together produce a material with properties that exceed the constituent materials. • Reinforcement phase (e.g., Fibers) • Binder phase (e.g., matrix phase resin) • Common examples • Wood , Packing paper , impregnated with wax. • Rain coat made of cloth impregnated with water-proof material and concrete.

  3. Composite materials – Advantages • Advantages • High strength and stiffness • Low weight Specific gravity • They are tough having good thermal shock resistance. • Thermal expansion , conductivity as well as electrical conductivity are low. • In many composites corrosion and oxidation resistance are much better than metals. • Large parts can often be fabricated more easily and cheaply than from other metals.

  4. Applications • Straw in clay construction by Egyptians • Aerospace industry • Sporting goods • Automotive • Construction • Land transportation • Marine industry

  5. Matrix phase/Reinforcement Phase Metal Ceramic Polymer Metal Powder metallurgy parts – combining immiscible metals Cermets (ceramic-metal composite) Brake pads Ceramic Cermets, TiC, TiCN Cemented carbides – used in tools Fiber-reinforced metals SiC reinforced Al2O3 Tool materials Fiberglass Polymer Kevlar fibers in an epoxy matrix Elemental (Carbon, Boron, etc.) Fiber reinforced metals Auto parts aerospace Rubber with carbon (tires) Boron, carbon reinforced plastics Types of Composites MMC’s CMC’s PMC’s Metal Matrix Composites Ceramic Matrix Comp’s. Polymer Matrix Comp’s

  6. Types of Composite Materials There are five basic types of composite materials: Fiber, particle,flake, laminar or layered and filled composites.

  7. 1-D gives maximum strength in one direction. 2-D gives strength in two directions. Isotropic gives strength equally in all directions. A. Fiber Composites In fiber composites, the fibers reinforce along the line of their length. Reinforcement may be mainly 1-D, 2-D or 3-D. Figure shows the three basic types of fiber orientation.

  8. Inherent fiber strength, Fiber length, Number of flaws Fiber shape The bonding of the fiber (equally stress distribution) Voids Moisture (coupling agents) Composite strength depends on following factors:

  9. B. Particle Composites • Particles usually reinforce a composite equally in all directions (called isotropic). Plastics, cermets and metals are examples of particles. • Particles used to strengthen a matrix do not do so in the same way as fibers. For one thing, particles are not directional like fibers. Spread at random through out a matrix, particles tend to reinforce in all directions equally. • Cermets (1) Oxide–Based cermets (e.g. Combination of Al2O3 with Cr) (2) Carbide–Based Cermets (e.g. Tungsten–carbide, titanium–carbide) • Metal–plastic particle composites (e.g. Aluminum, iron&steel, copper particles) • Metal–in–metal Particle Composites and Dispersion Hardened Alloys (e.g. Ceramic–oxide particles)

  10. C. Flake Composites - 1 • Flakes, because of their shape, usually reinforce in 2-D.Two common flake materials are glass and mica. (Also aluminum is used as metal flakes) C. Flake Composites -2 A flake composite consists of thin, flat flakes held together by a binder or placed in a matrix. Almost all flake composite matrixes are plastic resins. The most important flake materials are: Aluminum Mica Glass

  11. C. Flake Composites -3 Basically, flakes will provide: • Uniform mechanical properties in the plane of the flakes • Higher strength • Higher flexural modulus • Higher dielectric strength and heat resistance • Better resistance to penetration by liquids and vapor • Lower cost D. Laminar Composites - 1 Laminar composites involve two or more layers of the same or different materials. The layers can be arranged in different directions to give strength where needed.Speed boat hulls are among the many products of this kind.

  12. D. Laminar Composites - 2 • Like all composites laminar composites aim at combining constituents to produce properties that neither constituent alone would have. • In laminar composites outer metal is not called a matrix but a face. The inner metal, even if stronger, is not called a reinforcement. It is called a base. D. Laminar Composites - 3 We can divide laminar composites into three basic types: Unreinforced–layer composites (1) All–Metal (a) Plated and coated metals (electrogalvanized steel – steel plated with zinc) (b) Clad metals (aluminum–clad, copper–clad) (c) Multilayer metal laminates (tungsten, beryllium) (2) Metal–Nonmetal (metal with plastic, rubber, etc.) (3) Nonmetal (glass–plastic laminates, etc.) Reinforced–layer composites (laminae and laminates) Combined composites (reinforced–plastic laminates well bonded with steel, aluminum, copper, rubber, gold, etc.)

  13. A lamina (laminae) is any arrangement of unidirectional or wovenfibers in a matrix. Usually this arrangement is flat, although it may be curved, as in a shell. A laminate is a stack of lamina arranged with their main reinforcement in at least two different directions. D. Laminar Composites - 4

  14. E. Filled Composites • There are two types of filled composites. In one, filler materials are added to a normal composite result in strengthening the composite and reducing weight. The second type of filled composite consists of a skeletal 3-D matrix holding a second material. The most widely used composites of this kind are sandwich structures and honeycombs. F. Combined Composites It is possible to combine several different materials into a single composite. It is also possible to combine several different composites into a single product. A good example is a modern ski. (combination of wood as natural fiber, and layers as laminar composites)

  15. Fibre-Reinforced Plastic (FRP) • Polymeric substance + Solid filler = Reinforced Plastic • Filler acts as reinforcing material, while the polymer links the filler particles. • Using different matrix resins and reinforcing fibers and a variety of processing techniques, a multitude of products are manufactured. • Reinforcing fibers may be natural or synthetic organic or inorganic polymers such as jute, asbestos, nylon, polyester, aramides (Kevlar), glass, carbon, boron, aluminium, SiC. • The fiber and the resin are combined in a suitable manner to get desired properties.

  16. Fibre-Reinforced Plastic (FRP) contd…. • Properties: • Light weight & cost effective • High modulus & strong. • High impact strength • High creep & load • High service temperature • Not easily corroded • High melting points • Good dimensional stability • Good thermal & shock resistance • Good processability

  17. Fibre-Reinforced Plastic (FRP) contd…. • Applications: • Land transportation • Construction • Corrosion resistance equipment • Marine equipment • Electrical & Electronics industry • Various appliances & Business articles • Used in aircraft, aerospace & military goods, and • Automobiles. • For example,

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  19. Carbon Fiber-Reinforced Plastic (CFRP) • Polymeric substance + Carbon fiber = Reinforced Plastic • Carbon fibers can be combined usefully with a variety of plastic resins & polymers to yield composites of exceptionally high specific stiffness and strength. • Matrix materials; many thermosetting resins & thermo platics are suitable for combination with carbon fibers. • Thermosetting resins such as epoxides, epoxies, poly esters, phenolics, vinyl esters are used. • Thermoplastic resins such as polyamides, poly carbonates, polysulphones, etc… are used. • Properties: • High specific stiffness & strength • High specific modulus • Good mechanical strength • Creep resistance • Electrically conductive along with filament axis • Low thermal expansion & good chemical resistance.

  20. Carbon Fiber-Reinforced Plastic (CFRP) contd… • Applications: • In structural components such as air frame structures, space vehicles and satellites. • High speed reciprocating parts for industrial machinery and also for very high temperature machinery. • Used in Sports equipment

  21. Glass Fiber-Reinforced Plastic (GFRP) • Polymeric substance + glass fiber = Reinforced Plastic • Matrix materials are polypropylene, polyamide, polysulphones, polyimides, polyester ketones, polyester and epoxy resin. • Properties: • It has improved stiffness & strength than other materials. • Decrease shrinkage • Reduce thermal expansion • Good dimensional stability at high temperature.

  22. Glass Fiber-Reinforced Plastic (GFRP) contd… • Applications: • Bridges & airplane wings • Automobile industry • Boat hulls • Circuit boards & corrosion resistance equipment

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