DOLLAR G(A)-ALUMINA FOR CORDIERITE CERAMICS, PRODUCTION METHOD OF THE DOLLAR G(A)-ALUMINA AND STRUCTURES OF CORDIERITE CERAMICS USING THE DOLLAR G(A)-ALUMINA

摘要

alpha -Alumina for cordierite ceramics having a secondary particle size of 40-70 microm, a primary particle size of 1.5-3 microm, and a BET specific surface area of 0.5-1.5 m<2>/g as measured in its powder form is prepared. The prepared alpha -alumina is pulverized by means of a jet mill to obtain pulverized alpha -alumina that comprises alumina particles of 3 microm or less in an amount of 30 mass% or less and alumina particles of 15 microm or less in an amount of at least 75 mass% in relation to a particle size distribution profile of the pulverized alumina, and has a mean particle size of 4-10 microm and a +90-microm sieve residue of 50 ppm by mass or less. The thus obtained alpha -alumina is used to produce cordierite ceramics having a low coefficient of thermal expansion and high thermal shock resistance and exhibiting small variance in characteristics. Structures, such as catalyst carriers for use in a waste gas control apparatus and waste gas control filters, are produced from the cordierite ceramics.