초록 ▼

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 inte

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.

대표청구항 ▼

A method for making a composite ceramic article having a ceramic preform and an infiltrate phase, comprising the steps of: directionally solidifying by freezing a liquid medium containing a dispersion of ceramic particles to produce a green, porous ceramic preform wherein the dispersion is cooled to

A method for making a composite ceramic article having a ceramic preform and an infiltrate phase, comprising the steps of: directionally solidifying by freezing a liquid medium containing a dispersion of ceramic particles to produce a green, porous ceramic preform wherein the dispersion is cooled to a temperature below a freezing point of the liquid medium for a time sufficient to cause directional solidification within the liquid medium and progressive segregation of the liquid medium from the dispersion, wherein the directional solidification and segregation of the liquid medium causes a morphological ordering of a plurality of the ceramic particles into a plurality of interconnected lamelli or fibrils or mixtures thereof that are partially separated from one another by complementary interlamellar regions that form a green freeze dried ceramic preform; removing the solidified liquid medium from said preform; sintering the green freeze dried ceramic preform at a temperature and for a time sufficient to cause the plurality of ceramic particles to become bonded to one another; and infiltrating the interlamellar regions of the sintered ceramic preform with an infiltrate phase.