| 摘要 |
PURPOSE:To easily refine an obtained mullite precursor and to increase the density and strength of the sintered body formed from the precursor by allowing an aq. soln. of an aluminum compd. continuously to react with an aq. soln. of an alkali silicate under specified reaction conditions. CONSTITUTION:The aq. soln. of an aluminum compd. and the aq. soln. of an alkali silicate are supplied to the reaction zone so that the weight ratio of Al2O3 to SiO2 is controlled to 65/35-80/20. The mixture is subjected to a continuous reaction at the reaction temp. of >=80 deg.C, pH4-10 and the average retention time of >=30min. The grains are separated from the obtained slurry to obtain a mullite precursor. A batch process can be used instead of the continuous process. Namely, almost all the reaction conditions in the batch process are the same as those in the continuous process. The supply time of the raw material is controlled to >=30min, the supply of the raw material, etc., is stopped when a specified amt. of slurry is obtained, and the grains are separated from the obtained slurry. The precursor obtained by both processes is calcined to obtain mullite powder, and the mullite powder is formed and calcined to obtain a mullite sintered body. |
