Hydro-abrasive erosion and cavitation-silt erosion characteristics of HVOF sprayed WC-Ni cermet coatings under different flow velocities and sand concentrations

With widespread applications of hard ceramic/cermet coatings as wear-resisting materials, it is becoming pertinent to study their responses to hydro-abrasive erosion (HAE) and cavitation-silt erosion (CSE) in different multiphase flow conditions. In view of this, the HAE and CSE behaviors of a high-velocity oxygen-fuel (HVOF) sprayed WC-10Ni coating are explored on a rotating disk rig facility for different flow velocities (FV) and sand concentrations (SC) in the present study. The obtained findings show that the WC-10Ni coating possesses higher HAE and CSE resistances than those of the 1Cr18Ni9Ti stainless steel in a full range of FV and SC. A higher FV and SC helps to cause more severe HAE and CSE degradation for both the WC-10Ni coating and the 1Cr18Ni9Ti stainless steel. The significant factor promoting the influences of FV and SC on material degradation is cavitation erosion. The HAE process of the WC-10Ni coating mainly includes the pull-out of hard phase grains accompanied by micro-cutting and scoring of the soft binder matrix as well as the fracturing of hard phase grains. With the increase in the FV and SC, the WC-10Ni coating experiences the CSE process of erosion pits, scoring of the soft binder matrix, fracturing of hard phase grains, crater formation, coating spalling, and isolation of hard phase grains.