CERAMICS AND COMPOSITE MATERIALS

CERAMICS AND COMPOSITE MATERIALS

1. CERAMICS Inorganic solid

2. Introduction It’s a man made non metallic and inorganic solid

3. Traditional products Bricks Cook wares Cements Concretes Tiles potteries

4. Traditional products

5. Other engineering applications Used as tool for grinding and Cutting Bearings And many in electrical and electronics fields.

6. Other engineering applications

7. Characteristics of ceramics Used in high temperature places Its strong, hard and brittle High melting point Good thermal and electrical insulators Resistant to oxidation and corrosion Having high compressive strength but are weak intension

8. Engineering ceramics Its specially for engineering applications They are basically oxides, carbides, sulphides and nitrides of metal.

9. Characteristics of engineering ceramics High resistance to abrasion and wear High strength at high temperature Good chemical stability Good electrical insulation characteristics.

10. Important engineering ceramics Alumina (Al 2 O 3 ) Silicon Carbide ( SiC ) Silicon Nitride (Si 3 N 4 ) Partially stabilized Zirconia Sialons

11. Alumina ( aluminium oxide) Its produced from bauxite It’s a old engineering ceramic

12. BAUXITE ORE

13. Properties of Alumina Excellent hardness, wear resistance They are more stiffer than steel More stronger in compression than hardened steel Very good environmental resistance (CORROSION) Alumina mixed with ceramics to get high tensile and toughness properties .

14. Applications of alumina Used in Spark plug insulators Electronic circuits Rocket nozzles Electrical and electronics devices In nuclear power plant bearings

15. Silicon carbide (sic) It’s a semi conducting ceramic material Types Alpha Sic Beta Sic

16. Properties of Sic High tensile strength High stiffness , hardness Better dimensional stability Good wear resistant Good corrosion resistant.

17. Applications of Sic Used As a abrasives for grinding wheel As a coating material As a refractory tubes In nuclear reactor In bearings And in very high temperature places

18. Silicon nitrate (Si 3 n 4 ) It’s a use full ceramics in chemical industries

19. Properties of silicon nitrides Resistant to strong acids Resistance to thermal Low density and low weight Low thermal expansion More stiffer

20. Applications of silicon nitrides Used in Cutting tool materials Turbine parts Pump parts High temperature engineering components

21. Partially stabilized zirconia (PSZ) It’s a zirconium oxide Blended and sintered with others like magnesium oxide, calcium oxide

22. Properties of PSZ High tensile strength Low thermal conductivity

23. Applications of PSZ Used in As a blade in jet engine As a joint In furnace portions Internal combustion engine parts

24. Sialons They are Si – Al – O – N They are formed when Aluminium and oxygen partially substitute for silicon and nitrogen in silicon nitride

25. Properties of sialons High tough and strength Good mechanical properties Light weight Low co-efficient of thermal expansion

26. Applications of sialons Used in Cutting material Nozzles Welding shields Radiant heater tubes impellers

27. COMPOSITES TO GET A REQUIRE PROPERTIES IN METALS

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29. COMPOSITES Two or more materials added to get require qualities in a material. The weakness of one metal rectified by the strength of second metal Example Aerospace components That should have low weight , stiffness, impact and corrosion resistance, good abrasive properties.

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31. Particle re- inforced (FIBER) composites Its consist of particles of one material dispersed in a matrix of a second material The fine dispersion particle posses good strength in composites. The size, distribution and orientation of particles defines the strength of the composite. Types 1. dispersion strengthened composites 2. Large particle composites

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33. 1.Dispersion strengthened composites The particles are smaller and having diameter 0.01 – 0.1 microns and volume concentration 1 – 15 % of fiber This method is similar to that for precipitation hardening. Due to this , the composites have good yield and tensile strength. And the plastic deformation is restricted.

34. 2. Large particle composites The particles diameter greater than 1 micrometer and volume concentration are greater than 25 % Here the load on this composite is shared by both matrix and particles. It posses good strength Tungsten carbide or Titanium carbide embedded in a metal matrix of cobalt or nickel . These composites used as a cutting tool

35. FIBRE REINFORCED COMPOSITES Here the dispersed phase is in the form of fibers. These fibre reinforced composites having improved strength, fatigue resistant, stiffness and strength-to-weight ratio

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40. Advantages Good mechanical properties – high toughness, elastic modulus, good fatigue properties Used in light weight needed places We can fabricate to any shape and size Good aero- space applications than conventional materials. Good corrosion resistance Not much sensitive to thermal shocks and temperature changes.

41. Limitations High cost than many conventional materials Polymeric materials cannot be used for high temperature applications.

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