Plasma thermal performance of a dual-process PVD/PS tungsten coating on carbon-based panels for nuclear fusion application

Abstract

Various tungsten (W) coating techniques have been used for the application of plasma facing material in nuclear fusion devices, which resulted in limited success. In this study, a dual-process W coating structure was developed on a graphite substrate to improve the thermal performance of the coating structure. The dual-process coating structure consisted of a thin (similar to 7 mu m) multilayer W/Mo physical vapor deposition (PVD) coating layer deposited on top of the relatively thick (similar to 160 mu m) plasma spray (PS) W coating on a graphite substrate panel. Then the coated sample was exposed to plasma heat flux of 1-3 MW/m(2) for 300 s. With addition of a thin surface PVD coating layer, the microstructure change in underlying PS W coating was substantially reduced compared to the simple PS W coating structure. The thickness of overall coating structure was maintained for the dual-process PVD/PS coated samples after the thermal loading tests, while a significant reduction in thickness due to surface erosion was observed for the simple PS W coated samples. The improvement in surface erosion resistance in the dual-process coating structure was discussed in view of the characteristics of PVD and PS coating layers. (C) 2016 Elsevier B.V. All rights reserved