Properties and Characteristics of SiC and SiC/SiC Composites

The advantageous properties of SiC/SiC composites such as high temperature strength, creep and corrosion resistances, low density, high toughness, resistance to shocks, to fatigue and to damage, and reliability make them ideal candidates for the replacement of metals and ceramics in many engineering applications involving loads, high temperatures and aggressive environments. The CVI SiC/SiC composites, manufactured via Chemical Vapor Infiltration (CVI) process, are also promising for nuclear applications because of high crystallinity, high purity, near stoichiometry, and radiation resistance of the CVD SiC (β phase of SiC). An alternative processing technique based on the Liquid Phase Sintering technique (LPS) (Nano-powder Infiltration and Transient Eutectic-phase processing: NITE) was recently developed. The mechanical behavior shows features that differentiate SiC/SiC composites from monolithic ceramics and glasses, and from other composites. The main characteristics of CVD SiC, CVI SiC/SiC composites and NITE SiC/SiC composites are reviewed. Features of the mechanical behavior are discussed with respect to microstructure, on the basis of large amount of work produced on CVI SiC/SiC composites.