Preparation and Microstructure of Nextel 720/Mullite-Corundum Composite

Abstract

Oxide fiber/oxide matrix composites have been considered as an important and very attractive subpart of ceramic matrix composites because of their inherent stability in oxidization atmospheres at high temperature. Nextel 720 fibers reinforced mullite-corundum ceramic matrix composite was prepared by chemical vapor infiltration followed by sintering process. A mixed matrix including g-alumina and silica was obtained by chemical vapor infiltration at 550 o C using AlCl 3 -SiCl 4 -H 2 -CO 2 system. Then the mixture was crystallized into mullite-corundum matrix by sintering at 1260 o C. Effects of (H 2 +CO 2 )/(AlCl 3 +SiCl 4 ) flow ratio and total pressure on weight gain of preform were analyzed. SEM photographs of the composite showed the matrix surrounding filaments was dense and uniform.