Water droplet impingement erosion performance of WC-based coating sprayed by HVAF and HVOF

Abstract

In this work, a comparative study between two coating processes is explored to combat water droplet impingement erosion (WDIE) phenomenon. High velocity air fuel (HVAF) and high velocity oxygen fuel (HVOF) processes are used to spray WC-10Co-4Cr powder on Ti-6Al-4V. The WDIE tests were performed at 250, 300 and 350 m/s impact velocities. At 350 m/s, both HVAF and HVOF coating showed similar behaviour. This was attributed to the high induced stress which is significantly higher than the fracture strength of a WC-10Co coating. At 250 m/s and 300 m/s, gradual damage occurs due to accumulated impact and jetting, where HVAF outperformed HVOF coating. HVOF lower performance is attributable to the formation of unwanted brittle W2C phase.