SiC-Al_2O_3-Y_2O_3系セラミックスの機械的強度及び破壊靭性に及ぼす気孔率の影響

概要

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Influence of residual porosity on the flexural strength and fracture toughness of pressureless-sinterd α-SiC ceramic with controlled microstructure, characterized by equiaxed-grain and a mixture of equiaxed/plate grains were investigated together with the trend of σ-K_<IC> behavior. Both the flexural strength and the fracture toughness of the SiC ceramics showed an exponential decrease with porosity, but the extent of the porosity dependence was dependent on the microstructure ; a higher porosity-dependent strength was seen for the equiaxed-grain microstructure, while the dependence became weak for the mixed one. The trend of flexural strength-toughness dependence appeared to be positive and became more pronounced for the SiC ceramics with mixed-grain morphology, suggesting a strengthening effect due to the presence of reinforced platelike phase. Crack deflection appeared to be principal mechanism for toughness improvement in the SiC-Al_2O_3-Y_2O_3 ceramics.
社団法人日本セラミックス協会の論文
1995-09-01