Method of making a ceramic composite by infiltration of a ceramic preform

Abstract

A method for making a composite ceramic article by infiltration of a sintered ceramic preform with an infiltrate phase. The ceramic preform is made by directionally solidifying a liquid medium containing a dispersion of ceramic particles to produce a green, porous ceramic preform a plurality of interconnected lamelli that are partially separated from one another by complementary interlamellar regions, removing the solidified liquid medium and sintering the ceramic preform. This method may be used to make silicon carbide composites where a silicon carbide preform is first infiltrated with carbon to coat the lamelli of the preform, followed by infiltration of the carbon coated preform with molten silicon, whereby the molten silicon and carbon react to form silicon carbide in the interlamellar regions. The ceramic preform may also be coated with a thin, diffusion-inhibiting ceramic layer prior to infiltration in order to prevent interdiffusion between the lamelli of the preform and the infiltrate phase, and provide a plurality of mechanically weak, crack deflecting interfaces within the composite article.