Formation mechanism, microstructural features and dry-sliding behaviour of “Bronze/WC carbide” composite synthesised by atmospheric pulsed-plasma deposition

Abstract The present work was focused on the study of a composite metal-ceramic coating synthesised by atmospheric pulsed plasma deposition using an electro-thermal plasma accelerator. “Bronze/WC carbides” coating of 85–135 μm width was formed on the surface of grey cast iron due to high-current erosion of a sintered cathode (50 vol% of Al-bronze and 50 vol% WC) without post-plasma heat treatment. The work was conducted using OM, SEM/EDS, XRD, hardness and “Ball-on-Disc” dry-sliding testing. Numerical modelling and high-speed photo-shooting were applied to reveal the two-stage mechanism of the coating formation. The coating/substrate transitional layer was formed due to the dynamic interaction of a plasma flux with a plasma-melted substrate surface. WC carbides crystallised from the plasma flux in a transitional layer or they were embedded to the coating being transferred by plasma flux as unmolten angular particles. Wear test showed that the «Bronze/WC carbide” composite coating had much better tribological behaviour as compared to bulk copper under the friction against a steel ball. At the same time, the coating was inferior in wear resistance to copper when sliding against a SiC ball.