常圧焼結窒化ケイ素の800℃における混合モード破壊靱性

概要

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Fracture toughness of sintered silicon nitride under mode I and mode II was studied at 800℃ using controlled surface flaw in four point bending. Fracture paths in all cases were noncoplaner. The results were compared with various linear elastic fracture mechanics theories. The comparison showed that prediction by coplaner strain energy release rate theory, minimum strain energy density theory, and an empirical equation by Sigh and Shetty gave good agreement with the experimental values of this study. Normalized mixed-mode fracture toughness obtained at 800℃ were comparable to those obtained at room temperature. Moreover, the grain shearing on the fracture surface which fractured in mixed-mode loading was found by fractographic study. The influence of grain shearing to crack propagation direction was discussed based on the fractographic observations.
社団法人日本機械学会の論文
1991-02-25