Processing of ceria-coated alumina fiber/alumina matrix composite

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 0.25-0.50 M 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 degrees 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 degrees C. In the alumina-silica-ceria system, alpha-alumina, mullite (3Al(2)O(3). 2SiO(2)) and ceria coexisted at 1300-1500 degrees C in air. The ceria-coated alumina fabric was immersed in a well-dispersed alumina suspension of 15-25 vol% solid to form the alumina matrix. The treated fabric of 16 sheets was hot-pressed at 1200 degrees C to produce a dense composite of ceria-coated alumina fiber (47.5-56.6 vol%) /alumina matrix (43.4-52.5 vol%) with 98.4% of theoretical density. These composites fractured in the absence of plastic deformation.