窒化けい素における破壊応力と破壊靱性値の微視組織依存性

概要

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Microstructure and mechanical properties of HP, HP/GP and HP/HIP-Si_3N_4 were studied using scanning electron microscopy, bending tests and the indentation fracture method. The distribution of grain diameter was analyzed to clarify the relationship between microstructure and mechanical properties (bending strength and fracture toughness value). It is shown that bending strength increased with decreasing the grain diameter. The results also showed that a Hall-Petch relationship was recognized for grain diameter and fracture stress. The fracture toughness value shows a linear relationship with σ_F√<βd_a>, and is closely related to aspect ratio of Si_3N_4 grain. From these grain morphological analysis results, it is concluded that the microstructure composed of Si_3N_4 grains having both small grain diameter and large aspect ratio is effective to improve both fracture strength and fracture toughness.
一般社団法人日本機械学会の論文
1995-05-25