Patent ID: 6814917
Filing Date: 2004-11-09
Classification: A61L,C04B,H01L

Abstract:
A process for producing a polycrystalline alumina sintered body which comprises the steps of:preparing a slurry by subjecting alumina powder and a solvent to ultrasonic irradiation, mechanical stirring not using a grinding medium, or ultrasonic irradiation and mechanical stirring not using a grinding medium, to provide a slurry of alumina dispersed in a solvent; drying and forming said slurry to produce a green body; and then sintering said green body in an air atmosphere at a temperature in the range of 1400Â° C. to 1800Â° C.; wherein said alumina powder has: a purity of 99.99 wt % or more and comprises a alumina particles having a polyhedral shape, each having substantially no fractured surface, and having a D/H ratio of from 0.5 or more to 3.0 or less, wherein D represents a maximum particle diameter parallel to the hexagonal lattice plane of a hexagonal close packed lattice of &agr; alumina, and H represents a maximum particle diameter perpendicular to the hexagonal lattice plane of a hexagonal close packed lattice of &agr; alumina; a number-average particle size of from 0.1 &mgr;m or more to 1.0 &mgr;m or less; and a D90/D10 ratio of 7 or less, wherein D10 and D90 are the particle sizes at 10% cumulation diameter and 90% cumulation diameter, respectively, from the smallest particle side in a cumulative particle size distribution.