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

A method for making a composite ceramic article, comprising the steps of:

• directionally solidifying by freezing a liquid medium containing a dispersion of ceramic particles to produce a green porous ceramic preform comprising 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;
• coating the plurality of lamelli with a thin ceramic layer prior to a step of infiltrating the interlamellar regions, wherein the thin ceramic layer covers the plurality of lamelli and later inhibits bonding between the plurality of lamelli and an infiltrate phase during the step of infiltrating the interlamellar region;
• and
• infiltrating the interlamellar regions with the infiltrate phase.

A method of making a composite ceramic article, comprising the steps of:

• forming a porous, sintered ceramic preform by the steps comprising:
• forming a colloidally stabilized liquid dispersion comprising a plurality of ceramic particles and a liquid medium, wherein the ceramic particles are at least temporarily dispersed within the liquid medium;
• cooling the dispersion to a temperature below a freezing point of the liquid medium for a time sufficient to cause the directional solidification of the liquid medium and progressive segregation of the liquid medium from the dispersion, wherein the directional solidification and segregation of the liquid medium causes the morphological ordering of the plurality of the ceramic powder particles into a structure comprising a plurality of interconnected lamelli that are partially separated from one another by complementary interlamellar regions;
• removing the frozen liquid medium;
• and heating the article at a temperature and for a time sufficient to cause the plurality of ceramic particles to become sintered to one another, and
• infiltrating the interlamellar regions with an infiltrate phase.

A method of making a composite ceramic article, comprising the steps of:

• forming a porous, sintered ceramic preform by the steps comprising:
• forming a colloidal stabilized liquid dispersion comprising a plurality of ceramic particles and a liquid medium, wherein the ceramic particles are at least temporarily dispersed within the liquid medium;
• cooling the dispersion to a temperature below a freezing point of the liquid medium for a time sufficient to cause the directional solidification of the liquid medium and progressive segregation of the liquid medium from the dispersion, wherein the directional solidification and segregation of the liquid medium causes the morphological ordering of the plurality of the ceramic powder particles into a structure comprising a plurality of interconnected lamelli that are partially separated from one another by complementary interlamellar regions;
• removing the frozen liquid medium;
• and heating the article at a temperature and for a time sufficient to cause the plurality of ceramic particles to become sintered to one another;
• coating the plurality of lamelli with a thin ceramic layer prior to a step of infiltrating the interlamellar regions, wherein the thin ceramic layer substantially inhibits sintering between the plurality of lamelli and said infiltrate phase and is more susceptible to propagation of a crack than either said ceramic preform or said infiltrate phase;
• and
• infiltrating the interlamellar regions with an infiltrate phase.