Thermal property and microstructural characterization of W/SiC clad plates

A SiC/SiC composite is a candidate for the structural material of fusion reactors after Demonstration Power Plant (DEMO). Tungsten will be employed as an armor of SiC/SiC constructed divertor, the developments of fabrication method and optimization of thermal property of them are the important issues. Present research produced W and SiC/SiC clad plates using a diffusion bonding method and tried to investigate the thermal characters of the interphase between W and SiC/SiC composites. The thermal conductivities of W/SiC clad, SiC/SiC and tungsten plates were characterized by a laser flash method at temperatures up to 773 K. The thermal data was approximated by functions and applied as material data to an analysis by finite element method (FEM). The simple FEM model of the divertor suggested that the existence of the interfacial phase with low apparent thermal conductivity of the divertor system under the heat flux exposure of 5 MW/m² may cause fracture of the system due to thermal stress. The results show the importance of the improvement of the interphase to enhance the thermal properties and the reactor design to reduce thermal flux for the divertor surface.