| 摘要 |
A powdery alpha -alumina comprising single-crystal alpha -alumina grains which are homogeneous and free from any crystal seed inside, form an at least eight-sided polyhedron, and have a D to H ratio of 0.5 to 3.0 (wherein D is the maximum grain diameter in parallel with the hexagonal lattice plane of the alpha -alumina having a hexagonal closest lattice structure and H is the grain diameter perpendicular to the hexagonal lattice plane thereof), a number-average grain diameter of 0.1 to 5 mu m and a narrow grain size distribution. The powdery alpha -alumina of the invention comprises single-crystal alpha -alumina grains which are nearly spherical, fine and structurally homogeneous and have a narrow grain size distribution, and is suitable as the raw materials of abrasive, sinter, plasma spraying material, filler, single crystal, catalyst support, phosphor, sealing material and ceramic filter, in particular, as the raw materials of precision abrasive, sinter and ceramic filter, thus being remarkably useful from the industrial viewpoint. <IMAGE> |
