Investigation on the pressure infiltration of sol-gel processed textile ceramic matrix composites

Abstract

A pressure infiltration apparatus was used to fabricate textile ceramic matrix composites using sol-gel processing with added solid particles. A parabolic rate kinetics model for the infiltration process has been developed and experimentally verified. Darcy's law and a global permeability of the whole material system were adopted in the model. Experiments were conducted using both a 3-d angle interlock and a 2-d woven carbon fibre preform, and a silica sol containing silica particles of submicrometre sizes. The thickness of the particle compaction layer inside the 3-d preform is proportional to the square root of the processing time. The total infiltration time was inversely proportional to the constant processing pressure and increased significantly with reducing the solid particle size by a factor of two. The addition of a non-ionic surfactant reduced the surface energy which resulted in higher composite green density values of up to 90%. Sol-gel processing with added solid particles proved to be a viable method to fabricate textile ceramic matrix composites with a higher density and improved properties.