Modeling of a thermal-gradient chemical vapor infiltration process for production of silicon carbide whisker/alumina composite

Abstract

SiC whisker-reinforced Al 2O 3 composite was made by the chemical vapor infiltration (CVI) method. A porous preform was made from commercial SiC whiskers. Aluminum triisopropoxide was used as the reactant to deposit alumina. Reaction kinetics of the Al 2O 3 deposition were investigated experimentally. By inductive heating, it was possible to increase the temperature in the area closer to the center of the preform than at the outer surface. This led to a favorable deposition rate distribution in the preform, avoiding pore plugging. Infiltration proceeded from the center to the outer area of the preform. Hence, dense composite was obtained in a short processing time. A numerical model was developed to simulate this thermal-gradient CVI process. The experimental and calculated results were in good agreement. For the purpose of comparison, the conventional isothermal CVI method was also simulated. It was verified that by applying a temperature gradient, the processing time could be significantly reduced.