Slow crack growth behavior of silicon nitride ceramics in cryogenic environment

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• 作者：Jingya Gui ^{guijy13@mails.tsinghua.edu.cn" class="auth_mail" title="E-mail the corresponding author} ; Sai Wei ; Zhipeng Xie
• 关键词：SCG ; Dynamic fatigue ; Cryogenic environment ; Silicon nitride
• 刊名：Ceramics International
• 出版年：2016
• 出版时间：1 February 2016
• 年：2016
• 卷：42
• 期：2
• 页码：3687-3691
• 全文大小：2501 K

文摘

The slow crack growth behavior of Si₃N₄ ceramics in ambient and cryogenic environment had been investigated by dynamic fatigue testing. The fracture strength was principally dependent on stress rate at 293 K while the fracture strength was comparatively independent of stress rate at 77 K. The morphologies of the fracture surface and the crack tip region were examined to correlate with the slow crack growth behavior. The experimental results revealed that the Si₃N₄ ceramics exhibits a very high resistance to slow crack growth (SCG) in cryogenic environment. The reasons for such high resistance are likely related to the local residual stress associated with either the thermal anisotropies arising from the presence of the grain boundary glass phase, or from the crack tip shielding mechanism.