| 摘要 |
PURPOSE:To obtain a fine and uniform alpha-alumina containing no crystal seed in an inside and being made of alpha-alumina single crystal particle having a specific polyhedron shape by sintering a transition alumina in an atmospheric gas containing gaseous hydrogen chloride. CONSTITUTION:The transition alumina or an alumina raw material e.g. aluminum hydroxide to be the transition alumina by heat treating is sintered in the atmospheric gas containing >=1vol.% gaseous hydrogen chloride per total volume of the atmospheric gas. Thus, the uniform alpha-alumina containing no crystal seed in the inside, having >=8 faces polyhedron shape, being made of the alpha-alumina single crystal particle having 0.5-3D/H where the max. particle diameter parallel to the hexagonal lattice face of the alpha-alumina having hexagonal closed packed lattice is D and the particle diameter vertical to the hexagonal lattice face is H and having 0.1-5mum number average particle diameter is obtained. The alpha-alumina is useful for a precision abrasive material, a raw material for high purity sintered compact or the like. |
