SiC/SiC ceramic matrix composites with BN interphase produced by gas phase routes: An overview

The introduction of ceramic matrix composites (CMCs) into the hot sections of aircraft engines offers significant weight and fuel efficiency gains. The result of decades of research and development, CMCs are based on silicon carbide. They consist of a matrix reinforced with the latest generation of continuous fibres. The non-brittle behaviour of these materials is achieved by the "interphase", a thin coating of fibres. Boron nitride is the interphase material chosen to act as a mechanical fuse and to withstand the conditions of matrix manufacture and composite application. This paper considers the influence of the interphase on the mechanical properties of these CMCs and their behaviour in the different environments for which they are intended. Finally, the different preparation methods studied in the laboratory and the production methods used in industry are discussed, focusing on the gas phase routes.