Improvement of static fatigue strength of Si3N4/SiC crack-healed under cyclic stress
Improvement of static fatigue strength of Si3N4/SiC crack-healed under cyclic stress
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DOI：
10.1016/j.jeurceramsoc.2004.06.010
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发表时间：
2005-07
影响因子：
5.7
通讯作者：
Koji Takahashi;H. Murase;Shoko Yoshida;K. Houjou;K. Ando;S. Saito
中科院分区：
文献类型：
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作者：
Koji Takahashi;H. Murase;Shoko Yoshida;K. Houjou;K. Ando;S. Saito
采用热压法制备了Si3N4/SiC复合陶瓷，研究了其裂纹愈合性能和静疲劳强度。每个试样表面均形成100μm的半椭圆形裂纹。预裂试样在900、1000、1100和1200℃的空气循环弯曲应力为210MPa的条件下实现裂纹愈合。系统地研究了裂纹愈合试样在不同愈合温度下的弯曲强度和静疲劳强度。经900℃和1000℃静疲劳处理的试样的静疲劳强度低于1100℃和1200℃静疲劳强度。对静疲劳试样断口表面的详细研究表明，基体氧化对静疲劳强度有较强的影响。结果发现，试样在1300℃空气中预氧化后，表面覆盖一层氧化保护层，900℃和1000℃时的静疲劳强度显著提高。
Si3N4/SiC composite ceramics were hot-pressed in order to investigate their crack-healing behaviour and the resultant static fatigue strength. Semi-elliptical surface cracks of 100μm in surface length were made on each specimen. The pre-cracked specimens were crack-healed under a cyclic bending stress of 210MPa in air at 900, 1000, 1100, and 1200°C. The bending strength and static fatigue strength of the crack-healed specimens were systematically investigated at each healing temperature. The specimens which has been crack-healed and static fatigue-tested at 900 and 1000°C showed lower static fatigue strength than those tested at 1100 and 1200°C. Detailed investigation on the fracture surface of static fatigue-tested specimens showed that oxidation of the base material had strong effects on the static fatigue strength. It was found that if the specimens were pre-oxidized in air at 1300°C, the surface was covered by a protective oxide layer, leading to a significant improvement of static fatigue strength at 900 and 1000°C.