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

摘要

A Finite-element method (FEM) was applied for a simulation of the laser flash method for measuring thermal diffusivity. The effect of fiber and matrix thermal conductivities as well as the effect of fiber volume and fiber configuration on thermal diffusivity/conductivity of SiC/SiC composites was studied under some combinations of fibers and matrix-processing methods with changing fiber volumes of 1-D, 2-D, and 3-D fiber configurations. When using highly thermal conductive SiC fiber, the overall thermal diffusivity/conductivity of SiC/SiC composites with low matrix thermal conductivity is strongly improved with increasing the fiber volume especially for the 1-D fiber configuration. The calculation for 3-D SiC/SiC composites reveals that highly thermal conductive SiC fiber oriented to the through-the-thickness direction effectively contributes to increase the through-the-thickness thermal/diffusivity and that the fiber oriented to XY-plane has somewhat a positive effect when the fiber volume is increased due to fiber network and radially thermal diffusion in the fiber. The best X:Y:Z ratio of 3-D fiber configuration could be determined by a trade-off for obtaining better thermal and mechanical performance.