Evaluation of tungsten coatings on CuCrZr and W/Cu FGM under high heat flux and HT-7 limiter plasma irradiation

VPS-W coatings on CuCrZr with W/Cu interlayer and powder metallurgic W/Cu functionally graded material (FGM) were tested under high heat flux with active cooling and plasma irradiation in the HT-7 device. Results showed that after 10 MW/m2 thermal shock experiment, exfoliation and crack appeared, however, the interface was not damaged except a few pores. VPS-W can withstand 150 cycles for 100s pulses under 6 MW/m2. After plasma irradiation, tungsten carbide and tungsten oxide were observed by XPS analysis. Bubbles were observed on the surface of W/Cu FGM. These indicated that VPS-W coatings on CuCrZr with W/Cu interlayer have good thermal performance, and W/Cu interlayer was a better alternative compliant layer which can realize reliable W/CuCrZr joint, and the pore microstructure of VPS-W coating is helpful to inhibit the bubble formation.