Alumina sintered body and process for producing the same

摘要

A process for producing a polycrystalline alumina sintered body which comprises the steps of: subjecting alumina powder to ultrasonic irradiation, mechanical stirring not using a grinding medium, or ultrasonic irradiation and mechanical stirring not using a grinding medium, resulting in slurry 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 1400 DEG C to 1800 DEG C; wherein said alumina powder having a purity of 99.99 wt% or more comprises a polyhedral particle having substantially no fractured surface, and comprises alpha alumina particles having polyhedral shape; a D/H ratio of from 0.5 or more to 3.0 or less; the number-average particle size of from 0.1 mu m or more to 1.0 mu m or less; a D90/D10 ratio of 7 or less.