PRODUCTION OF MULLITE PRECURSOR, MULLITE POWDER AND MULLITE SINTERED COMPACT

摘要

PURPOSE:To obtain a mullite precursor reduced in unevenness of Al/Si ratio in micro level by continuing to stir while controlling ratio of an acidic Al compound in reaction system to Na2SiO3 before and after feeding the acidic AL compound and neutralizing the produced precipitate-containing aqueous solution. CONSTITUTION:A mullite precursor is produced according to the following method from a precipitate obtained by blending an aqueous solution of acidic Al compound with Na2SiO3 aqueous solution and neutralizing the blend: An aqueous solution of Na2SiO3 or aqueous solution of Na2SiO3 and acidic Al compound are stirred so that the acidic Al compound in reaction system may be excess to Na2SiO3 before finishing feed and ratio expressed in terms of Al2O3/SiO2 may be a ratio in mullite when the feed is over. Then the stirring is continued and after forming precipitation, the precipitate-containing aqueous solution is neutralized by NaOH aqueous solution. As a result, mullite precursor being about 70/30-74/26 in Al/Si ratio in micro level is obtained. Mullite powder obtained by drying the precursor is formed and then burned to provide the mullite sintered compact having excellent strength, etc.