| 摘要 |
PURPOSE:To provide an electric insulator porcelain of high waterproofing and thermal conductivity, by sintering at low temperature a mixture containing MgO as main constitutent, B2O3 and CaO as auxiliary constituents and minute amounts of BeO, ZnO, etc. CONSTITUTION:The porcelain contains 75 to 99% by weight of MgO, 0.5 to 15% by weight of B2O3 and 0.5 to 10% by weight of CaO. The mixture may contain 5% or less by weight of at least one of nine kinds of oxides such as BeO, ZnO, SrO, BaO, Ta2O5, etc. (in this case, the amount of the MgO is 70 to 99% by weight). To obtain such a composition, oxide, carbonate, nitrate and oxalate are mixed with one another. The mixture is tentatively baked at a temperature of about 800 deg.C. Then, the baked mixture is pulverized. The pulverized powder is molded by a press. The molded piece is sintered at a temperature of 1000 to 1300 deg.C, thereby producing the electric insulator porcelain. This porcelain has a water absorption factor of 0.1 % or less and a thermal conductivity of 0.04 Cal sec deg.C cm at 300 deg.C. |
