Patent ID: 7696116

Claim:
A ceramic composite material consisting essentially of: a. a crystalline ceramic matrix material having a porosity less than 10%, the ceramic material being other than eucryptite; and b. eucryptite particles dispersed in the matrix material, the particles having a size between 0.1 and 10 microns and the volume fraction of the particles being between 5 and 20 volume percent, wherein at least some of the eucryptite particles are ε-eucryptite particles wherein the ceramic composite material is made by forming a mixture comprising particles of β-eucryptite and particles of the non-eucryptite ceramic material, sintering the mixture to form a precursor composite material having β-eucryptite particles dispersed in the non-eucryptite ceramic matrix material, and cooling the precursor composite material, the non-eucryptite ceramic material being selected so that the cooling process leads to compressive stresses in the vicinity of the β-eucryptite particles sufficient to transform at least some of the β-eucryptite particles to ε-eucryptite particles.