High-temperature oxidation and tribological behaviors of WTaVCr alloy coating prepared by double glow plasma surface alloying technology

Abstract

Tungsten-based refractory high entropy alloys (RHEAs) are a potential candidate for plasma-facing materials (PFM) due to their excellent properties. However, the oxidation resistance of W-based RHEAs is poor. Moreover, there is still a lack of research on the evaluation of room temperature wear. In this work, several WTaVCr alloy coatings were fabricated by double glow plasma surface alloying (DGPSA) technology at different temperatures and different source ratios. The microstructure of WTaVCr coatings exhibited BCC solid solution phase. The coatings were compact and uniform. The scratch test indicates that the coating combines the substrate well. The surface hardness of the samples increases significantly after alloying, which is 5 times that of the substrate. Sliding wear tests were performed on the coating as well as the substrate. The fairly low specific wear rate of the coating (W31.7Ta13.3V42.9Cr12.2) proved its excellent wear-resisting property (The wear rate was 8 × 10−7 mm3/N∙m, which was two orders of magnitude lower than that of the substrate), and the dominant wear mechanism was abrasive wear and oxidative wear. The coating (W45Ta45.4V4.5Cr5.1) showed a favorable oxidation resistance, and a continuous Cr2O3 protective layer was formed on the surface. The oxidation resistance of the coating was approximately a quarter of the W-substrate.