Electric insulating polycrystalline silicon carbide and process for the preparation thereof by isostatic hot pressing

Abstract From the Canadian patent

The invention is an electrically insulating sintered polycrystalline silicon carbide and a sintering aid consisting essentially of at least 95.0% by weight silicon carbide 0.25 to 3.5%, by weight aluminum oxide and/or magnesium oxide up to 0.3% by weight, free carbon and up to 0.03% by weight impurities due to elements of groups 3a and 5a of the Periodic System (predominantly A1 + B + N) in total, wherein the SiC has an essentially homogeneous isotropic microstructure with grain sizes of at most 5 µm aluminum oxide, and/or magnesium oxide are present predominantly at the grain boundaries of the SiC and are detectable as separate phase(s) having the following properties; thermal conductivity …