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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热传导系数的单胞模型。模型简化了编织结构纱线的实际构型,充分考虑了编织结构复合材料由于化学气相渗透(CVI)工艺制备陶瓷基复合材料产生的孔洞对热传导系数的影响。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、孔洞体积含量对复合材料热传导系数的影响规律。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,热传导系数减小;当其它参数不变时,热传导系数随着纤维体积含量和孔洞体积含量的增加而下降。利用Hot Disk热测量仪采用瞬变平面热源法测试了二维编织C/SiC复合材料面内的热传导系数,试验结果与模型预测结果吻合较好。
According to the meso-structure of the two-dimensional braided C / SiC composites and the characteristics of the preparation process, a single cell model for predicting the thermal conductivity of the material was proposed. The model simplifies the actual configuration of the braided yarns and fully considers the influence of the cavities produced by the CVI process on the thermal conductivity of braided composites. The single cell model was used to predict the influence of structural parameters, fiber volume content and pore volume content of two-dimensional braided C / SiC on the thermal conductivity of composites. The results show that the thermal conductivity decreases with the increase of the ratio of gap to yarn width at the kink of the fiber bundle. The thermal conductivity decreases with the increase of fiber volume content and void volume when the other parameters are constant. The thermal conductivity of two-dimensional braided C / SiC composites was tested by the Hot Plane Thermal Meter with transient planar heat source method. The experimental results agree well with the model predictions.