FATIGUE CRACK PROPAGATION BEHAVIOR OF Si_3N_4CERAMICS IN CORROSIVE ENVIRONMENTS

概要

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The effect of corrosion on fatigue fracturing of silicon nitride ceramics was investigated in 1N and 3N H_2SO_4 solutions. The crack propagation rate da dt increased when the stress ratio R under cyclic loading was decreased. The higher concentrated solution enlarges the stress ratio dependence of da/dt. Therefore, it is considered that corrosion increases the effect of cyclic loading on da/dt. According to results of an energy dispersive X-ray spectroscopy(EDX)analysis, it was found that the sinterring additive components of Al and Y decreased at the crack tip. This suggests that the grain boundary phase at the region dissolved. In addition, a similar effect was also observed by scanning electron microscopy(SEM). Consequently, it is concluded that the dissolution of the grain boundary phase contributes to the increase of da/dt in H_2SO_4 solutions.
社団法人日本材料学会の論文
1996-09-15