| 摘要 |
PURPOSE:To prepare high purity boron carbide powder free from isolated C, by preheating a powdery mixture of a boron compound, Mg, etc., and C or a C- source, subjecting to the reduction reaction at a specific temperature to remove MgO, etc., and heating at a higher temperature. CONSTITUTION:The starting raw material mixture composed of boric acid and/ or boron oxide, Mg and/or Ca, and C or a C-source, is dehydrated by preheating below the temperature to start the reduction reaction, i.e. at 300-600 deg.C. After the heat treatment, the powdery mixture is subjected to the reduction neaction at 700-1,200 deg.C in an inert or reductive atmosphere. The MgO or CaO existing in the reaction mixure as a contaminant is dissolved and removed by leaching with hyrochloric acid or sulfuric acid, and the mixture is heated in an inert or reductive atmosphere at 1,300-2,000 deg.C to complete the carbide formation reaction. A high purity boron carbide can be prepared by this process. |
