Process for producing alumina silica sintered ceramics having improved high-temperature strength

摘要

An alumina silica sintered ceramic that is produced by the normal sintering method and which has bending strength of at least 300 MPa at room temperature and at least 400 MPa at an elevated temperature, for example, 1,300 DEG C. is disclosed. This sintered ceramic is produced by a process comprising the following steps: providing a chiefly amorphous starting powder that consists of 62-73 wt % Al2O3 and correspondingly 38-27 wt % SiO2; calcining this starting powder to make a calcined product that is chiefly composed of a crystalline phase and which contains oxides of an alkali metal and an alkaline earth metal in a total amount of no more than 1,500 ppm; pressing the ground particles of the calcined product into a compact; and sintering the compact at 1,500 DEG -1,750 DEG C. and at atmospheric pressure.