Production, properties and applications of ceramic matrix composites

Of the ceramic matrix composite (CMC) materials reinforced with long fibers, only those with SiC matrix applications have until now achieved technological meaning because production processes that do not adversely affect these fibers are well developed for these ceramics. This includes chemical vapour infiltration (CVI), the impregnation and pyrolysis of organic silicon polymers (LPI), and the infiltration of melted silicon in CMCs. These processes result in different materials with specific individual properties that correspond to the demands from the application areas. The CVI materials C/SiC and SiC/SiC, which display the best mechanical properties, are preferred for use as bearing components. The LPI technique is chosen for the production of large, complex C/SiC structures for aerospace applications. The liquid silicon process supplies a material (C/C-SiC) that is excellent for the use in brake discs.