| 摘要 |
PURPOSE:To obtain a boron nitride based compact calcined under ordinary pressure containing BN, Al2O3 and high-silicate glass at a specific ratio, having a relative density of specific value or above and improved shape restriction and productivity as well as high density and strength and good abrasion resistance, thermal shock resistance and corrosion resistance. CONSTITUTION:The aimed boron nitride based compact calcined under ordinary pressure consists of 70-15wt.% BN, 5-75wt.% Al2O and 10-80wt.% high-silicate glass and has >=55% relative density. The above-mentioned high-silicate glass means boron silicate glass existing in the state where the surface of silica particle is coated with a film of boron oxide and is obtained e.g., by the following method: Borate or boron oxide is added at an amount of about 2-10wt.% as B2O3 to SiO2 existing in the ultrafine particle state and the blend is calcined at about 800-1300 deg.C to afford a calcined compact, which is then pulverized and repeatedly calcined at the above- mentioned temperature and pulverized. The above-mentioned boron nitride compact calcined under ordinary pressure is obtained e.g., by blending each raw material at a prescribed ratio, pulverizing the blend under non-oxidizing atmosphere and then molding the powder and calcining the resultant compact. |
