高強度窒化ケイ素セラミックスの曲げ強度に及ぼす破壊起点および微細組織の影響(セラミック材料小特集)

概要

論文の詳細を見る
The effects of fracture origin and microstructure on bending strength have been investigated with four kinds of Si_3N_4 ceramics. The mean grain sizes of three kinds of Si_3N_4 ceramics were 0.2 μm and the other one was 0.4 μm. The average bending strength of the weakest one was 1000 MPa and the strongest one was 1500 MPa. Three kinds of defects, pores, anomalously grown grains and inclusions (Fe) were identified as fracture origins. The stresses applied at these fracture origins were calculated from the bending strength and the locations of fracture origins. As the parameter to describe the size of fracture origin, the equivalent crack length was estimated. The strength of the high-strength Si_3N_4 ceramics with more than 1500 MPa depended on both the grain size and the defect size same as conventional-strength Si_3N_4 and agreed with the Kishimoto's equation, from which the fracture strength could be estimated by using defect size, grain size and fracture toughness.
社団法人日本材料学会の論文
1994-06-15