Tensile creep behavior of notched two-dimensional-C/SiC composite
Tensile creep behavior of notched two-dimensional-C/SiC composite
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DOI：
10.1016/j.compscitech.2005.08.008
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发表时间：
2006-06
影响因子：
9.1
通讯作者：
Wu Xiaojun;Q. Sheng-ru;Hou Juntao;Zhao Qing;Han. Dong;L. Mei
中科院分区：
文献类型：
--
作者：
Wu Xiaojun;Q. Sheng-ru;Hou Juntao;Zhao Qing;Han. Dong;L. Mei
在1100、1300和1500°C真空条件下，对具有双边弧形缺口的二维C/SiC试样进行了拉伸蠕变试验。在不同的蠕变时间下，检测了表面基体裂纹和共振频率。在1100°C时，光滑试样和缺口试样的蠕变应变都集中在瞬态阶段，稳态蠕变速率几乎为零;而在1500°C时，缺口试样和光滑试样的稳态蠕变速率相近。蠕变损伤主要集中在缺口附近。切口附近区域和编织纤维束交叉点处出现微裂纹，切口附近的纵向纤维容易断裂。两种类型的曲线，即微裂纹数量与时间和微裂纹宽度与时间，是非常相似的蠕变曲线。一般情况下，微裂纹在前10 h内发展较快。研究发现，在初始的2 h内，缺口附近的微裂纹比远离缺口的微裂纹增长快，而在2 h后，远离缺口的微裂纹比靠近缺口的微裂纹增长快。这一现象表明蠕变过程中存在应力重分布。1300和1500°C下的损伤曲线具有相似的趋势，但1500°C下的损伤和微裂纹数量高于1300°C下的损伤和微裂纹数量。
Tensile creep tests of two-dimensional-C/SiC specimens with double-edge arc notches have been carried out at 1100, 1300 and 1500°C in vacuum. The matrix cracks on the surface and resonance frequency were examined at different creeping times. At 1100°C, the creep strains of both smooth and notched specimens were concentrated at the transient stage and the steady creep rates were nearly zero, whereas steady creep rates of notched specimens and smooth specimens were similar at 1500°C. It has been observed that the creep damage mainly concentrated at the area near the notches. Micro-cracks appeared in the area near the notches and on the cross-points of the woven fiber bundles, and the longitudinal fibers near the notches fractured easily. Both types of curves, namely quantity of micro-cracks vs. time and micro-crack width vs. time, were extremely similar as for the creep curves. In general, micro-cracks developed fast during the first 10h. It has been noticed that within the first 2h, the micro-cracks near the notches grow faster than those far from the notches, whereas the growth rate of micro-cracks far from notches was faster than those near the notches after 2h. This phenomenon indicates the stress redistribution during creep. Damage curves at 1300 and 1500°C have similar trend, though the damage and the quantity of micro-cracks at 1500°C are higher than those at 1300°C.