| 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 deg.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 deg.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. |
