Evolution of friction products and wear mechanism of plasma transfer arc welding Ni-WC coating at 200 °C and different load conditions

Ni-WC coating was prepared by plasma transfer arc welding. According to the application scenario of the pinch roll, the evolution of the friction products and wear mechanism of the coating when countering against the H13 steel under different friction loads at 200 °C was investigated. The results showed that at a friction load of 10–40 N, the main friction product was iron oxide generated on the H13 steel, and the oxides were transferred to the friction surface of the coating. When the load was 30 N, due to severe material transfer, the wear rate of the coating reached a maximum value of 13.73 × 10⁻⁵ mm³/(N·m). But when the load was 40 N, the formation of compacted oxide layer hindered the formation of stress concentration layer and reduced wear. When the load was 50 N, a continuous adhesive layer of iron-carbon oxide was formed, which further suppressed the formation of oxides and material transfer, thereby reducing the wear rate to 1.79 × 10⁻⁵ mm³/(N·m). When the friction load increased from 10-20 N–30 N, 40 N, and 50 N, the wear mechanism shifted from abrasive wear to oxidative and abrasive wear, oxidative wear, and adhesive wear in sequence.