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, fatigue, and 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 SiC/SiC composites manufactured via the chemical vapor infiltration (CVI) process (CVI SiC/SiC) are also promising for nuclear applications because of their high crystallinity, high purity, near stoichiometry, and radiation resistance of the chemical vapor deposition (CVD) SiC (β-phase of SiC). An alternative processing technique based on the liquid phase sintering technique (LPS) (nanopowder infiltration and transient eutectic-phase processing, NITE) has been developed recently. The mechanical behavior shows features that differentiate SiC/SiC composites from monolithic ceramics and glasses, as well as from other composites. The main characteristics of CVD SiC, CVI SiC/SiC, and NITE-SiC/SiC are reviewed in this chapter. Features of the mechanical behavior are discussed with respect to the microstructure, on the basis of a large amount of work done on CVI SiC/SiC.