CERAMIC MATRIX COMPOSITES; MICROSTRUCTURE AND THERMOSTRUCTURAL PERFORMANCE LIMITS

摘要

The post 1970s materials era has been especially active in the development of novel intermetallic and ceramic microstructures for lightweight rigid components which have potential for high temperature engineering application. This has been encouraged by the needs of the aerospace industries, in particular and the realisation that more conventional alloy systems have reached a development limit in relation to high temperature stability and deformation resistance. A well-publicised example is that of gas turbine components in which Ni-based Super-alloys typically limited to ～ 1000°C are operating at gas flow temperatures of 1600°C only with the aid of forced cooling air and an associated loss in thermal efficiency. The substitution of ceramics for metallic alloy components operating at surface temperatures requiring extreme cooling (1400-1800°C) or marginal cooling (1100-1300°C) offers a substantial performance or efficiency gain.