When the peak intensity of the diffraction peak designating

摘要

PROBLEM TO BE SOLVED: To reduce a graphite phase in a sintered compact and to produce a dense high strength boron carbide sintered compact.;SOLUTION: Boron carbide powder having ≤5 μm average particle diameter is mixed with 4-12 wt.% metallic boron powder having ≤3 μm average particle diameter, 0.5-5 wt.% (expressed in terms of silicon carbide) metallic silicon powder or powdery metallic silicon-silicon carbide mixture having ≤5 μm average particle diameter and 0.5-5 wt.% carbon source such as carbon powder. The resultant mixture is compacted and subjected to purification treatment in vacuum at 1,600-2,100°C until the total amount of alkali metals, alkaline earth metals and transition metals is reduced to ≤300 ppm. The purified compact is fired at 1,900-2,250°C to obtain the objective boron carbide sintered compact having ≥96% relative density. In X-ray diffraction measurement, the ratio (Ib/Ia) of the peak intensity Ib of the (002) plane of graphite to the peak intensity Ia of the (021) plane of boron carbide in the sintered compact is ≤0.01.;COPYRIGHT: (C)2000,JPO