RAW MATERIAL POWDER OF MULLITE BASED SINTERED COMPACT AND PRODUCTION OF MULLITE BASED SINTERED COMPACT

摘要

PURPOSE:To obtain raw material powder capable of readily producing having sufficiently large strength, reduced in dispersion of strength and being small in lowering of strength at high temperature by specifying mullite crystal diameter, Al2O3/SiO2 ratio, average particle diameter and shape. CONSTITUTION:When a mixture of alumina sol and silica sol is sprayed to provide globular mullite based powder, the resultant powder has =200mum mullite crystal diameter, weight ratio of Al2O3/SiO2 of 40/60 to 80/20 and =10mum average particle diameter. A raw material containing the mullite based globular powder is formed and burned to readily provide the objective mullite based sintered compact having sufficiently large strength, reduced in dispersion of strength and being small in lowering of strength at high temperature. When crystal size thereof exceeds 200nm or average particle diameter thereof exceeds 10mum, in the above-mentioned raw material powder, the powder becomes difficult to sinter and it becomes difficult to obtain sintered compact having sufficient strength. Through Al2O3/SiO2 ratio is used in the above-mentioned range, when high-temperature strength is regarded as important, amount of SiO2 is preferably reduced.