Process for producing a improved beta-sialon sinter

摘要

A process for producing a beta-sialon sinter comprises wet -mixing a starting material composed of (a) a sintering aid (0.5-20 wt. % pref. 3-15%) (b) an additive (3-40 wt. % pref. 7-35 wt. %) and (c) beta-sialon powder (the rest) then drying, and sintering it. (c) is represented by general formula Si6-zAlzOzN8-z (where z = 0-4.2 pref. z = 0-2) and has a mean particle size of 2.0 micron or less (pref. 1.0 or less). The mean particle size of (a) is 5.0micron (a) comprises MgO, Y203 or an oxide of a rare earth element. (b) is a cpd. composed of B4C, BN, TiB2, TiC or TiN and has a particle size of 5.0 micron or less. The fraction toughness (KIC) of the beta-sialon sinter is 6.5 MPam1/2 or higher. The particulate size of both (a) and (b) is pref. 2.0 micron or less. The pref. sintering aid is MgO and/or Y203. The pref. additive is SiC and/or B4C. The liquid used for the wet-mixing process is isopropanol or n-hexane. The obtd. dried sinter is moulded under a pressure of 100 kgf/cm2 and sintered at 1720-1850 deg.C in a nitrogen atmos.