NONLEAD GLAZE COMPOSITION FOR ALUMINA AND GLAZED ALUMINA

摘要

PROBLEM TO BE SOLVED: To obtain a glaze composition for an alumina sintered body having the same or more characteristics of a glass layer formed by baking the glaze composition at a temperature lower than the conventional one, and further to provide a glazed alumina having the glass layer formed by the baking at a lower temperature and having the same or more characteristics compared to the conventional one, on the surface. ;SOLUTION: This nonlead glaze composition for an alumina sintered body usable for formation of a glass layer 34 of an insulator 12 consists essentially of B2O3, CaO and Al2O3 in the proportion of 70 mol%, 20 mol% and 10 mol% respectively based on 100 mol% total thereof. The essential components are included in the proportion of about 90 wt.% based on the total of the glaze composition. As a result, the softening point is the sufficiently low one of about 640°C, and the baking temperature is lowered to about 850°C. The thermal expansion coefficient is about 6.0(×10-6/°C) and nearly same as the one of the alumina sintered body constituting the insulator 12, and thereby the insulator is excellent in heat resistance. Further, the glaze composition has high insulation properties of ≥8.9 (MΩ.cm) volume resistance at 500°C under 1,000 V application.;COPYRIGHT: (C)2000,JPO