An Investigation of the Effect of Post Heat Treatment on the Wear and Corrosion Behavior of HVOF-sprayed WC-10Co4Cr Coatings

The impact of heat treatment on the wear and corrosion behavior of WC-10Co4Cr coating was investigated in this study. Firstly, the prepared samples were subjected to argon protection heat treatments at 550, 750 and 950 degrees C. The samples were characterized using SEM, XRD and microhardness testing. The results showed that the change in temperature affected the phase transformation and mechanical properties. The coating did not undergo a phase change after the heat treatment at 550 degrees C, while the transformation of the eta-phase occurred in the coating after heat treatment at 750 and 950 degrees C. However, heat treatment of the coating led to adhesive failure, resulting in partial separation between the coating and substrate. Due to the formation of hard phases, the wear resistance of the coating was improved after heat treatment, with the main wear mechanisms being micro-cutting and delamination. According to the corrosion test results, the corrosion resistance of the coating was significantly improved after heat treatment at 950 degrees C, with a reduction of 78.1% in its corrosion rate in 3.5 wt.% NaCl compared to the original coating. This was attributed to the precipitation of eta-phase and recrystallization of the bonding phase in the coating which reduced the micro-cell effect within the coating.