The present work stems from a development programme considering the use of WC–Co thermal spraycoatings in galvanising applications. In such applications, service conditions include exposure to air at 450°C. It is generally accepted that WC–Co composites do not oxidise significantly in air at temperatures below 500°C. However, the present results show significant oxidation of such coatingsat 450°C in air and in contact with a molten galvanising alloy. There appear to be two simultaneous oxidation reactions occurring, with WO3 forming from the tungsten carbide and tungsten phases and CoWO4 derived from the β-Co and cobalt containing carbide phases.
