2000 Volume 108 Issue 1261 Pages 823-829
The surface of alumina and silica-alumina fibers was coated with ceria to avoid the sintering between the fibers and alumina matrix and to promote the pull-out of fibers in the oxide fibers/alumina matrix composites. A cerium nitrate solution of 0.25-0.50M at pH 2.0-6.0 was infiltrated into the spaces of woven fabric of the oxide fibers. The infiltrated cerium nitrate was thermally decomposed at 400°C in air to form a cerium oxide layer. No reaction was observed in the X-ray diffraction patterns for the alumina-ceria system at 1300-1500°C. In the alumina-silica-ceria system, α-alumina, mullite (3Al2O3⋅2SiO2) and ceria coexisted at 1300-1500°C in air. The ceria-coated alumina fabric was immersed in a well-dispersed alumina suspension of 15-25vol% solid to form the alumina matrix. The treated fabric of 16 sheets was hot-pressed at 1200°C to produce a dense composite of ceria-coated alumina fiber (47.5-56.6vol%)/alumina matrix (43.4-52.5vol%) with 98.4% of theoretical density. These composites fractured in the absence of plastic deformation.
