Particle Size-Dependent Tribological Responses in WC-FeNiCrCu_0.5 Coatings Sprayed by Supersonic Atmospheric Plasma Spraying

Thermal sprayed WC-based metal carbide coatings exceptional hardness and superior wear resistance, indicating significant application potential for surface protection of critical equipment in nuclear environments. Nevertheless, the facile activation of metal binders (such as Co) under prolonged nuclear radiation significantly restricts their stability during operation. In this study, a WC-FeNiCrCu_0.5 coating with high-entropy alloy (HEA) as a metal binder was fabricated by supersonic atmospheric plasma spraying (SAPS). The influence of WC particle size on the microstructure and tribological responses of the coating was comparatively studied. The results suggested that the WC-HEA coatings primarily consisted of WC, W₂C, W₂(C, O), and FCC phases. A tight bond was realized between WC and the metal binder inside the coatings, leading to high density. Notably, the inclusion of nano-sized WC as the hard phase achieved a synergistic enhancement of both hardness and toughness. This outcome significantly decreased the wear rate (6.75 × 10⁻⁶ mm³·N⁻¹·m⁻¹) and enhanced wear resistance. The wear mechanism of the coatings was mainly associated with abrasive wear, accompanied by oxidation wear. The wear debris mainly contained of Cr₂O₃, NiO, Fe₃O₄, and WO₃ phases.