A Finite-element analysis of the thermal diffudivity/conductivity of SiC/SiC composites

SiC/SiC複合材料の熱拡散率の有限要素法解析

山田 禮司; 井川 直樹   ; 田口 富嗣

Yamada, Reiji; Igawa, Naoki; Taguchi, Tomitsugu

SiC/SiC複合材料の熱拡散率測定の計算機シミレーションを有限要素法で行った。SiC繊維とマトリックスの熱伝導率及びSiC繊維の体積率をパラメータに、複合材料の熱拡散率の計算を200と900のケースで行った。その結果、一般のSiC繊維では繊維体積の増加とともにSiC/SiC複合材料の熱拡散率は減少するが、結晶性に優れかつ結晶粒の大きなSiC繊維の場合には減少することは無く、むしろマトリックスの熱伝導率が比較的小さい場合、SiC繊維の増加とともにより大きな値を示した。これらの傾向は、絶対値を別にすれば、200及び900において共通に見られた。

A Finite-element method(FEM) was applied for a computer simulation of a laser flash method for measuring thermal diffusivity of SiC/SiC composites. To understand the effect of individual fiber and matrix thermal conductivities as well as fiber volume on the overall composite's thermal diffusivity, the cases of high and low values for the fiber and matrix thermal conductivities were calculated as a function of fiber volume fraction at specimen temperatures of 200 and 900. The results of calculations showed that if low thermal conductive SiC fibers were used, the increase of fiber volume worsened the composite thermal diffusivity with highly conductive matrix, whereas when using highly conductive SiC fiber, the effect of increasing fiber volume was positive for increasing the composite diffusivity with low matrix thermal conductivity. The specimen temperatures altered the values of the composite thermal diffusivity but the qualitative tendencies above mentioned were maintained.