Chemical vapor infiltration isothermal

The reinforcing fibers are usually CVD SiC or modified aluminum oxide. A common matrix material is SiC deposited by chemical-vapor infiltration (CVI) (see Ch. 5). The CVD reaction is based on the decomposition of methyl-trichlorosilane at 1200°C. Densities approaching 90% are reported.b l Another common matrix material is Si3N4 which is deposited by isothermal CVI using the reaction of ammonia and silicon tetrachloride in hydrogen at 1100-1300°C and a total pressure of 5 torr.l" " ] The energy of fracture of such a composite is considerably higher than that of unreinforced hot-pressed silicon nitride. 

Table 1 Typical tensile properties of isothermal chemical vapor infiltration processed C/SiC...

B.W. Sheldon and T.M. Besmaim, Reaction and Diffusion Kinetics During the Iititial Stages of Isothermal Chemical Vapor Infiltration, Journal of American Ceramic Society, Vol.74, 1991, p.3046. 

J.Y. Ofori and S.V. Sotirchos, Optimal Pressures and Temperature for Isobaric, Isothermal Chemical Vapor Infiltration, American Institute of Chemical Engineers Journal, Vol.42, No. 10, 1996, p.2828. 

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