Thermal diffusivity/conductivity of Tyranno SA fiber- and Hi-Nicalon Type S fiber-reinforced 3-D SiC/SiC composites

Thermal diffusivity measurements for 3D-SiC/SiC composites reinforced with either Tyranno SA or Hi-Nicalon Type S fibers were performed by laser flash method. The 3D weaves with several X:Y:Z fiber configurations were directly woven from each fiber bundle, and the SiC composites were fabricated by either isothermal CVI or PIP/CVI process. For the 3D-Tyranno SA-CVI and -PIP/CVI composites the measured thermal conductivity values were 40–50 W/mK and 35–40 W/mK at RT, respectively, and about 24 and 18 W/mK at 1000 °C, respectively. For the 3D-Hi-Nicalon Type S-CVI composites, the values were about 36 and 20 W/mK for RT and 1000 °C, respectively. These fairly high thermal conductivity values were attributable to their high fiber and matrix densities. The influence of the 3D-fiber configuration on the overall composite thermal conductivity was observed in the temperature range less than 600 °C.