Effect of crack-healing and proof-testing procedures on fatigue strength and reliability of Si3N4/SiC composites
Effect of crack-healing and proof-testing procedures on fatigue strength and reliability of Si3N4/SiC composites
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DOI：
10.1016/s0955-2219(02)00232-7
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发表时间：
2003-05
影响因子：
5.7
通讯作者：
K. Ando;M. Chu;S. Matsushita;S. Sato
中科院分区：
文献类型：
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作者：
K. Ando;M. Chu;S. Matsushita;S. Sato
采用热压法制备了Si 3 N4/SiC复合材料。使用这种材料，在1000-1400 °C下对裂纹愈合和验证测试的试样进行疲劳测试。用维氏硬度计在试样表面引入直径约110 μm的椭圆形裂纹。裂纹愈合主要在空气中在1300 °C下进行1小时。裂纹愈合和验证试样（C.P试样）的疲劳极限随试验温度的升高而略有下降。然而，裂纹愈合的试样对高达1400 °C的低周疲劳不敏感，疲劳极限几乎等于每个温度下的最低弯曲强度。为了研究原因，在1200 °C的空气中系统地进行了循环应力下的裂纹愈合行为。110 μm的表面裂纹在1200 °C的空气中，在频率为0.001 ~ 5 Hz的循环应力作用下可以完全愈合。由此可以得出结论，[裂纹愈合+验证试验]和使用期间的裂纹愈合是保持这些陶瓷部件结构完整性的有用技术。
A Si3N4/SiC composite was hot-pressed. Using this material, fatigue tests on crack-healed and proof-tested specimens were conducted at 1000–1400 °C. A surface elliptical-crack of about 110 μm in diameter was introduced on the specimens using a Vickers hardness indenter. The crack-healing was performed at 1300 °C for 1 h in air, mainly. The fatigue limit of the crack-healed and proof-tested specimen (C.P specimen) decreased slightly with increasing test temperature. However, the crack-healed specimen is not sensitive to low-cycle fatigue up to 1400 °C, and the fatigue limit is almost equal to the minimum bending strength at each temperature. To investigate the reason, the crack-healing behavior under cyclic stress was carried out systematically at 1200 °C in air. A 110 μm surface crack could be healed perfectly at 1200 °C in air under cyclic stress with a frequency of 0.001–5 Hz. From this, it can be concluded that [crack-healing+proof test] and crack-healing during service are useful techniques for maintaining structural integrity of these ceramic components.