SINTERED ALUMINA CERAMIC, METHOD FOR PRODUCING THE SAME, ANDCUTTING TOOL

摘要

A sintered alumina ceramic obtained by preparing a raw material powder mixture containing alumina and a Group 3A metal oxide or a Group 3A metal compound which provides a Group 3A metal oxide on heating, and firing said r aw material powder mixture. The sintered ceramic contains alumina particles having an average particle diameter of 4.0 .mu.m or smaller. In the sintered ceramic, the total content of alkali metal elements, alkaline earth metal elements, elemental S i, and elemental Ti as converted to oxides accounts for 0.1 mol or less with respec t to 100 mol of alumina, the total peak intensity for the principal peaks for ReAlO3 and Re3Al5O12 (Re: Group 3A metal) amounts to from 1 to 75% of the intensity of the principal peak of alumina as measured by X-ray diffraction, and the relative density is 99.0% or higher with respect to the theoretical density.