Performance of thermal-sprayed WC-Cr₃C₂-Ni coatings in slurry erosion for hydrodynamic turbines

Abstract

Hydrodynamic turbine and slurry pump components are frequently influenced by severe wear due to the impact of solid particles present in the water. A WC-based coatings deposited by thermal spray techniques is known for the protection against slurry erosion. In the present work, WC-Cr 3 C 2 -Ni powder was sprayed on a turbine steel substrate using high-velocity oxyfuel (HVOF) and atmospheric plasma spray (APS) techniques. Microstructural and phase constitutions of as-sprayed coatings were examined. The effect of speed, slurry concentration and particle size on slurry erosion resistances of both coatings and substrate materials was comparatively studied in a slurry pot erosion tester. The results exhibit that the HVOF coating has better properties in terms of density, micro-hardness and slurry erosion resistance than those of APS coating. The improvement in slurry erosion resistance of bare turbine steel by using APS and HVOF coatings is approximately 37% and 62%, respectively.