C/SiC composites for high temperature structural applications.: Part I:: thermodynamical and chemical stability

The development of aero-engine and aircraft industry is aimed to hypersonic technology, efficiency enhancements and pollutant emission reductions. This objective can only be reached by increasing the operating temperatures, utilising new materials which mechanical properties are retained up to high temperatures. SiC matrix composites reinforced with carbon fibres (C/SiC) are good examples with very good bending and thermal shock resistance at temperatures up to 1600 degreesC as well as low density. However, the fact which currently inhibits the application of these materials is the high oxidation rate of carbon fibres at temperatures above 450 degreesC. Ln the first part of the paper, a review of the most important properties and oxidation mechanisms of C and SiC has been carried out. The influence of each material disposition, individually and as composite, has been analysed.