Effects of temperature and of oxidation on the interfacial shear stress between fibres and matrix in ceramic-matrix composites
Effects of temperature and of oxidation on the interfacial shear stress between fibres and matrix in ceramic-matrix composites
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DOI：
10.1016/s1359-6454(98)80029-3
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发表时间：
1998-04
期刊：
影响因子：
9.4
通讯作者：
P. Reynaud;D. Rouby;G. Fantozzi
中科院分区：
文献类型：
--
作者：
P. Reynaud;D. Rouby;G. Fantozzi
在循环载荷作用下，SiC/SiC、SiC/ MAS-L陶瓷基复合材料的力学行为随循环次数的变化而变化，表现为寿命图和应力/应变环的形状演变。根据这些观察，已经开发了一个剪切滞后模型，其中循环疲劳效应归因于纤维和基体之间的界面磨损。在惰性气氛下的高温下，由于物理和化学变化受到抑制，温度对陶瓷基复合材料循环疲劳的主要影响是径向热残余应力的释放。但是在真空下，当温度高时，由于化学不稳定性，纤维/基体界面可以被去除。因此，SiC/SiC复合材料经高温真空时效后，其室温循环疲劳滞后先增大后减小。这可以通过由于先前在真空下高温下加热而导致的界面剪切应力的降低来解释。对于这种处理的复合材料，在循环疲劳过程中，也观察到一个原始的硬化效果。这种原始现象归因于横向纱线中的裂纹的贡献。
Under cyclic loading, the mechanical behavior of ceramic matrix composites (SiC/SiC, SiC/ MAS-L) changes with the number of applied cycles, as shown by life-time diagrams and shape evolutions of stress/strain loops. According to these observations, a shear-lag model has been developed where the cyclic fatigue effect is attributed to an interfacial wear between fibres and matrix. At high temperature under inert atmosphere, since physical and chemical changes are inhibited, the main effect of temperature on cyclic fatigue of ceramic matrix composites is the release of radial thermal residual stresses. But under vacuum when the temperature is high, fibre/matrix interfaces can be removed due to chemical instabilities. Hence, after ageing under vacuum at high temperature, cyclic fatigue at room temperature of SiC/SiC composites exhibits an increase followed by a decrease in mechanical hysteresis. This can be explained by a decrease in the interfacial shear stress due to the previous heating at high temperature under vacuum. For such treated composites, an original stiffening effect is also observed during cyclic fatigue. This original phenomenon is attributed to a contribution of cracks in transversal yarns.