二维编织 C/ SiC复合材料的热膨胀系数预测
Prediction on coeff icient of thermal expansion for 22D braided C/ SiC composites
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摘要: 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。Abstract: A unit cell model based on meso - structure and preparation procedure is presented for the in-plane
coefficient of thermal expansion (CTE) of 22D braided C/ SiC composites. In this unit cell model the actual st rand cross-2 section geometry and possible gap between two adjacent st rands are taken into account . The influence of st ructure parameters on the 22D braided C/ SiC composites?coefficient of thermal expansion was predicted. The predicted result s show that the composites?CTE increases with increase of kinking distance , but decreases with increase of fiber volume fraction and void volume f raction. The test result shows that there is a good correlation between the predicted result s and the experimental values.
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