| 摘要 |
Satisfactorily sinterable a-alumina which readily sinters at a low temperature and which, upon sintering at 1,500°C for 3 hours, gives a sinter having a bulk density of 3.90 g/cm3 or higher. It changes little in density upon sintering and has excellent sintering properties. Also provided is a process for producing the a-alumina. The a-alumina with satisfactory suitability for sintering is one produced by sintering aluminum hydroxide obtained by the Bayer process. When sintered under the conditions of 1,500°C and 3 hours, the a-alumina gives a sinter having a bulk density (A) [(mass of sintered sample)/(volume of sintered sample)] of 3.90 g/cm3 or higher. The density change between the sinter bulk density (A) and a sinter bulk density (B) as measured after sintering at 1,600°C for 3 hours, {[(B-A)/A] 100}, is 1% or less. The a-alumina is produced by introducing aluminum hydroxide having a soda content of 0.1 mass% or lower into a stationary burning furnace under such conditions as to result in a compact bulk density of 1.0 g/cm3 or lower, burning the compact, and pulverizing the burning product. |
