B_4C-SiCウイスカー系複合セラミックスの機械的特性

概要

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Composite ceramics of B_4C containing up to 30 vol% SiC whisker were fabricated by hot pressing at 2000°-2200℃ under 30 MPa for 30 min. The mechanical properties (bending strength, fracture toughness, hardness, elastic modulus) of the hot pressed bodies were measured. Fully dense B_4C-SiC whisker composite ceramics were obtained at the whisker contents up to 30 vol% at a sintering temperature above 2100℃. These composites had maximum strength at the whisker content of 10 or 20 vol% depending upon the hot pressing temperature. The composite containing 10 vol% SiC whisker, fired at 2100℃, had the highest strength (about 830 MPa), which was 40% larger than that of monolithic B_4C. Slight increase of fracture toughness were obtained in the composites because there was no pull-out of whiskers and no crack deflection in the fracture process. The strength and fracture toughness of the composites containing whiskers with a small diameter were lower than those of the composites with a large diameter, since the whiskers with a small diameter could not maintain their original morphology after sintering. The hardness and elastic modulus were 30 GPa and 430 GPa, respectively, independent of whisker addition.
社団法人日本セラミックス協会の論文
1990-10-01