Silicon carbide (SiC) ceramic matrix composites are being investigated as a new generation of fuel cladding materials due to its higher accident tolerance compared to Zircaloy. Characterization of the thermal conductivity of SiC constituents and their interfaces and interphases in SiC/SiC composites is needed as inputs to models of cladding performance. We used time-domain thermoreflectance (TDTR) to map the thermal conductivity with a spatial resolution of 2 µm. The SiC/SiC composite is comprised of Hi-Nicalon Type S fibers in a matrix made by chemical vapor infiltration (CVI matrix). The interphase material is a pyrolytic carbon/SiC multilayer. We report thermal conductivity maps of the SiC fiber and SiC matrix at temperatures of 25°C, 90°C, 164°C, and 250°C. The fiber has a uniform and isotropic thermal conductivity of 22 W m⁻¹ K⁻¹ at 25°C; the thermal conductivity of fiber is approximately independent of temperature. The matrix thermal conductivity is not uniform and varies from 50 to 120 W m⁻¹ K⁻¹ at 25°C; the thermal conductivity of the matrix scales approximately with the inverse of the square root of temperature, i.e., ∝ 1/T^1/2. The thermal conductivity of the interphase at room temperature is 6 W m⁻¹ K⁻¹. The calculated spatially averaged thermal conductivity of this SiC/SiC composite at 1000°C is 29 W m⁻¹ K⁻¹.

由于碳化硅（SiC）陶瓷基复合材料具有比Zircaloy更高的事故承受能力，因此正在被研究作为新一代燃料覆层材料。SiC / SiC复合材料中SiC成分及其界面和相间的导热系数需要作为熔覆性能模型的输入。我们使用时域热反射（TDTR）来绘制空间分辨率为2 µm的导热系数。SiC / SiC复合材料由Hi-Nicalon S型纤维组成，该纤维位于通过化学气相渗透制成的基质（CVI基质）中。相间材料是热解碳/ SiC多层。我们报告了在25°C，90°C，164°C和250°C的温度下SiC纤维和SiC基体的导热系数图。纤维具有22 W m的均匀且各向同性的热导率在25°C时为^-1 K ^-1 ; 纤维的热导率大约与温度无关。基质的导热系数不均匀，在25°C时为50至120 W m ^-1 K ^-1；矩阵的热导率大约与温度的平方根成反比，即∝ 1 / T ^1/2。室温下相间的热导率为6 W m ^-1 K ^-1。该SiC / SiC复合材料在1000℃下的空间平均导热系数为29Wm ^-1 K ^-1。