Plasma Facing Materials (PFMs) suffer from very high heat load including quasi-stationary high heat load during normal operation and transient events with extremely high heat load during normal plasma operation and off-normal events. In this paper, W/Cu functional gradient coating was applied on CuCrZr substrate (250mm × 120mm × 30mm) with compositionally gradient W/Cu as bond coat (0.4-0.6 mm) and 1.5 mm thickness W coating as top coat via VPS for continuous deposition duration of 5 h. VPS-W/CuCrZr mockup with built-in cooling channel was prepared for evaluating the transient vertical displacement and plasma disruption events applied by high energy electron beam. The formation of cracks and surface melting of VPS W/Cu mockup were investigated under the two transient high heat loads (HHL). The coatings were able to absorb about 2 MJ/m2 in HHL without significant damage.

This study investigates the microstructure, thermal conductivity, hardness, and strength of Cu-Cr-Zr coatings produced by cold gas spraying. The elements in the powders were found to have a significant influence on microstructure, particle morphology, and strengthening mechanisms. The strengthening mechanisms of copper alloy coatings include fine crystal reinforcing, solution strengthening, work hardening, and dispersal reinforcing. Different mechanisms are shown to be more or less effective depending on powder composition and the presence of impurities. By filtering impurities before gas atomization, the thermal conductivity of as-sprayed Cu-Cr-Zr coatings can be improved by a factor of two.

Advanced materials are the crucial factors determining the successful application of future nuclear fusion energy. Plasma facing materials (PFMs) are one of the most important armor materials in nuclear fusion experiment devices for direct facing with the extremely high thermal load, thermal shock and strong irradiation of high energy particles. W coated CuCrZr substrate has been considered as one of the candidates to the armor materials due to its high melting point, chemical stability and good thermal conductivity. However it was a challenge to obtain high strength thick W coatings because of the major difference of CTE between the W and CuCrZr substrate. In this paper, graded W/Cu layers were deposited as the bond layer via Low Pressure Plasma Spraying (LPPS) on the CuCrZr substrate. Subsequently, thick LPPS W coatings over 1.5 mm were prepared as the top layer. The adhesive and cohesive strengths for thick W coatings on CuCrZr substrates were evaluated according to the standard of ASTM C633. The results showed that the oxide formation on the W coating surface rapidly deteriorated the coating microstructure and properties.

A previous study indicated that dense thick Cu-4Cr-2Nb coatings could be formed by cold spraying, and the post-spray heat treatment could significantly influence the microstructure and microhardness of the as-sprayed Cu- 4Cr-2Nb coatings. In this study, the tensile strength and fracture performance of the Cu-4Cr-2Nb coatings after annealing were investigated. The vacuum heat treatment was conducted under 10-2 Pa at 850°C for 4 h. Results showed that the heat treatment had a great contribution to the healing-up of the incompleteness of the interfaces between the deposited particles. In addition, the coating microhardness decreased from 156.8±4.6 Hv0.2 for the as-sprayed coatings to 101.7±4.5 Hv 0.2 for the annealed ones. The mean tensile strength of the annealed coatings was approximately 298.8±31.5 MPa compared to that of 45±10.5 MPa for the as-sprayed ones, which results from the partially metallurgically bonded zones between the deposited particles inducing by the heat treatment process.