1757 CMC CERAMIC MATRIX COMPOSITES -Gautam Shah
Ceramic matrix composites have evolved in this century. Mechanically joined or composed entities have dual material components, which when face high temperatures, are beset with different thermal behaviours. To expect to sustain their integrity and remain operative, is a difficult proposition.
Components used in boilers, chimneys, exhausts, heat sinks, combustion engines, furnaces, rocket nozzles, etc., become soft, if, of metals or their alloys. Here the traditional ceramics, can offer some degree of good heat durability, abrasion resistance, and non corrosive properties, but brittleness is always an issue over a longer period due to the uncertainty of failure. Ceramics by themselves are often not conductive of heat, electricity, though this can be altered by suitable coating or insulation. Traditional components of Metal and Ceramics, expand differently, causing issues of integrity.
Ceramic-Metal composites have matrix or filler of both, metal or ceramics, in any of the roles. The processing at high temperature, causes melting or softening of the material. Polymers and Metals can go through such melting-softening temperatures, but ceramics have own limitations.
CMCs offer properties like, high thermal-shock resistance, predictable and good high-temperature stability, excellent hardness and corrosion resistance, light weight, non- magnetic and non-conductive.
Ceramic Metal composites have gained a new meaning due to their near zero traceability by radars of war objects such as missiles, air-crafts, drones, submarines, etc. These composites have low eight and so are used in rockets.
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