SOLID PARTICLE EROSION RESISTANCE OF HVAF-SPRAYED WC-10Co-4Cr COATING ON CA6NM STEEL

Abstract

In the present investigation, WC-10Co-4Cr coating was deposited by high velocity air-fuel (HVAF) process on CA6NM hydro turbine steel. A detailed microstructural and phase compositional study was carried out on the coating. Mechanical properties of the coating were also evaluated. WC-10Co-4Cr coating showed a homogeneous, well-bonded structure with low porosity, which is mainly attributed to less decarburization of WC. Erosion resistance of the coating was evaluated by air jet erosion tester at three different impingement angles (30[Formula: see text], 60[Formula: see text] and 90[Formula: see text]) for 35 and 70[Formula: see text]m/s impact velocities. The FESEM micrographs were taken, before and after erosion tests, to determine the erosion mechanism. The test results revealed that the coating protects the substrate at 30[Formula: see text], 60[Formula: see text] and 90[Formula: see text] impingement angles. At 70[Formula: see text]m/s impact velocity, uncoated and coated steel showed higher cumulative volume loss than in the case of 35[Formula: see text]m/s impact velocity. It was observed that uncoated steel showed a ductile behavior during erosion and WC-10Co-4Cr coating showed mixed (ductile and brittle) mode of fracture during erosion.