High Performance Ceramics For Structural Applications

Abstract

The main drawback of monolithic ceramics is their brittle failure behaviour and the thus dissatisfactory damage tolerance of ceramic components. The most favorable way to improve their fracture toughness is the reinforcement with thermally stable fibres. Commercially available carbon fibres represent the most economical fibre reinforcement and different processing techniques are currently under investigation to embed them in a matrix of silicon carbide. A very cost efficient manufacturing route for those ceramic matrix composites (CMC) has been developed by DLR. The process is based on the infiltration of molten silicon into porous carbon/carbon preforms, which replaces the initial pore volume of the preform and reacts subsequently with the carbon matrix to form silicon carbide. CMC materials of high mass specific properties and of excellent thermal shock resistance have been achieved. This paper deals with principles in designing and manufacturing of C/C-SiC components and describes some applications where these ceramic materials are very attractive alternatives to conventional metals.