薄界面3DC/SiC复合材料的热震损伤机制

Damaging mechanism of 3D C/SiC composite with thin interlayer during thermal shock process

为了研究薄界面3DC／SiC复合材料的热震行为，利用高频加热器在氩气保护环境中进行了700—1200℃的热震试验，然后基于热震试验后复合材料微结构变化和剩余强度变化，结合热应力的计算，确定了薄界面3DC／SiC复合材料的热震损伤机制。研究发现，在700～1200℃之间热震时，薄界面3DC／SiC复合材料会发生基体开裂和界面脱粘。基体开裂与裂纹扩展导致复合材料强度降低，界面脱粘导致复合材料强度提高。薄界面3DC／SiC复合材料的基体裂纹在热震50次左右达到饱和，裂纹饱和前，强度逐渐降低；裂纹饱和后，强度逐渐提高。

To investigate the thermal shock behaviors of 3D C/SiC composite with thin interlayer, thermal shock tests were carried out at 700 - 1 200℃ temperature in Ar gas atmosphere by means of heating generators. The damaging mechanism of 3D C/SiC composite with thin interlayer during thermal shock process was defined based on mierestructure,residual tensile strength and thermal stress calculation. The investigation results show that matrix cracking and interface debending occur during the thermal shock process at 700 - 1 200℃ temperature. The strength decrease of 3D C/SiC composite with thin interlayer results from the matrix cracking and crack extension, and the strength of the composite can be improved by interface debonding. The micro-cracks of matrix reach saturation state after 50 times thermal shock. The strength decrease before saturation and increase after saturation gradually.