粒界にSiO_2を添加した短繊維SiC強化Si_3N_4複合材料の破壊挙動

概要

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Si_3N_4/SiC chopped fiber composites with various amounts of Si0_2 at the grain boundary were fabricated by hot isostatic pressing (HIP) . The SiC fibers (average diameter 130 μm) were chopped with high aspect ratio and randomly dispersed in the matrix. Em phasis was placed on characterizing the fracture properties of the composites in comparison with the Si_3N_4 matrix material. A carbon layer of about 3 μm, deposited on the surface of the fibers, was found to be very suitable for enhancing the pull out process during fracture extension. As a result, catastrophic fracture from notches or pre existing cracks could be avoided and the work of fracture (WOF) of the composite materials displayed values about 7-8 times higher than that of the matrix (i.e.,〜80 J/m^2). However, some physical limitations mainly related to the stereological arrangement of the fibers in the matrix, made the critical stress intensity for crack propagation (K_<Ic>) of the composites almost the sarne as that of the matrix, in dependently of the presence of the SiC fibers and the added amount of Si0_2.
社団法人日本セラミックス協会の論文
1995-12-01