Performance of HVAF sprayed WC-10Co-4Cr coating onto cast 21-4N steel for slurry erosion: Characterization and erosion rate studies

Abstract

In this study, 86WC-10Co-4Cr powder was thermally sprayed onto cast 21-4N steel using High Velocity Air-Fuel (HVAF) technology. The deposited coating exhibited a dense structure with minimal porosity (1.0 ± 0.3%) and excellent fracture toughness (5.1 ± 0.3 MPa m1/2). Slurry erosion tests had shown that the HVAF-coated steel had significantly improved erosion resistance compared to uncoated steel, attributed to its high hardness, fracture toughness, and dense microstructure. Statistical analysis revealed that slurry velocity and impact angle were the most influential parameters. Further, Field emission scanning electron microscope (FE-SEM) image analysis showed that the coated steel exhibited a brittle mode of material removal, while the bare steel displayed a ductile mode. Overall, the study highlights the effectiveness of HVAF-sprayed 86WC-10Co-4Cr coatings in enhancing erosion resistance, providing valuable insights into the coating’s microstructure and performance under different erosion conditions.