Fabrication of silicon carbide whisker/alumina composite by thermal-gradient chemical vapor infiltration

SIC(w)/Al2O3 composites were made from an AlCl3-H2CO2 mixture by a thermal- gradient chemical vapor infiltration (CVI) method. Al2O3 was deposited from the reaction of AlCl3 and H2O, which was produced from the oxidation of H- 2 by CO2. The densification rate was measured at various reactant compositi ons and total pressures. When the reaction rate or total pressure increased , the rate-controling step shifted from H2O production to AlCl3 diffusion, which led to premature pore closing. To obtain dense composites in a short infiltration time, the diffusion rate of AlCl3 had to be increased by decre asing the total pressure.