Sliding wear performance of cobalt-based alloys in molten-Al-added zinc bath

Pin-on-disk sliding wear tests were conducted in a molten Zn-18% Al (wt.%) bath at 470°C to evaluate the wear performance of as-cast Stellite 6 and Tribaloy 800, and PTA (plasma transferred arc) well-surfaced Stellite 6 with 35% and 50% WC-Co. Wear performances of PTA weld-surfaced Stellite 6 with 35% WC-Co and 50% WC-Co are not effective when coupled with the same materials although their hardnesses are the highest compared to other materials tested. When Tribaloy 800 is coupled with PT35 (PTA weld-surfaced Stellite 6 with 35% WC-Co) and PT50 (PTA weld-surfaced Stellite 6 with 50% WC-Co), only Tribaloy 800 would be damaged and part of worn Tribaloy 800 would be transferred to the counterpart PT35 or PT50 materials regardless of disk and pin combinations. Although overall wear rates of both pin and disk are similar between Stellite 6 and Tribaloy 800, the wear mechanism is quite different. While harder eutectic carbides are broken and detached in Stellite 6, the softer matrix is preferentially attacked without pulling out harder phases in Tribaloy 800 during the wear testing.