Evaluation of the integrity of divertor models of tungsten or SiC/SiC composites joined with copper

From viewpoints of thermal shock resistance, control of plasma particles, low activation, thermal efficiency and so on, it is planned to use heat-resisting metals and ceramic composites as plasma facing materials for the next experimental, demonstrative and commercial fusion reactors. In this study, a tungsten material and SiC/SiC composites were joined with oxygen free copper as a heat sink material using foils of titanium and copper, and a molybdenum plate was also inserted for the relaxation of residual thermal stresses in the case of a SiC/SiC-copper joint. The divertor model specimens using the joining materials were manufactured and heat load tests were carried out. Thermal cracks in the tungsten material and delaminating cracks at the joining boundary of SiC/SiC composites were observed during several heat load tests. Therefore, tungsten and SiC/SiC composites need to be improved further with respect to the thermal shock resistance, thermal conductivity and fracture toughness.