| 摘要 |
A coated refractory composition for making high quality preforms comprising a refractory material selected from a metal refractory carbide, metal refractory nitride, metal refractory boride or diamond having a coating layer of hydrous alumina or a coating layer of anhydrous crystalline alumina, and to a method for enhancing dispersibility and improving oxidation resistance of such compositions. Further, a composition comprising an alpha alumina substrate having a first coating layer of calcium pyrophosphate and a second coating layer of hydrous alumina, and to a calcined composition comprising an alpha alumina substrate having a first coating layer of calcium pyrophosphate and a second coating layer of a densified anhydrous, crystalline form of alumina and to a method for preparing the same. |
