二维编织C/SiC复合材料的热膨胀系数预测

Prediction on coefficient of thermal expansion for 2-D braided C/SiC composites

根据二维编织C/SiC复合材料的细观结构及其制备工艺特点,提出了一种预测该材料面内热膨胀系数的单胞模型。模型充分考虑了编织结构复合材料中的纤维束弯曲和CVI工艺制备陶瓷基复合材料产生的孔洞对热膨胀系数的影响。利用单胞模型预测了二维编织C/SiC的结构参数、纤维体积含量、孔洞含量对复合材料热膨胀系数的影响规律,结果表明:随着纤维束扭结处产生间隙与纱线宽度比值的增大,热膨胀系数增大;当其它参数不变时,随着纤维体积含量的增大,热膨胀系数反而下降;随着孔洞含量的增加,热膨胀系数也出现了下降的趋势。利用DIL402C热膨胀仪测试了二维编织C/SiC复合材料纵向热膨胀系数,试验结果与模型预测结果吻合较好。

A unit cell model based on meso-structure and preparation procedure is presented for the in-plane coefficient of thermal expansion （CTE） of 2-D braided C/SiC composites. In this unit cell model the actual strand cross-section geometry and possible gap between two adjacent strands are taken into account. The influence of structure parameters on the 2-D braided C/SiC composites＇ coefficient of thermal expansion was predicted. The predicted results show that the composites＇ CTE increases with increase of kinking distance, but decreases with increase of fiber volume fraction and void volume fraction. The test result shows that there is a good correlation between the predicted results and the experimental values.