Microstructure and mechanical property of high velocity oxy-fuel sprayed WC-Cr3C2-Ni coatings

Abstract

WC-Cr3C2-12Ni coatings, with Cr3C2 weight content of 10% and 30%, were fabricated on steel substrate by high velocity oxy-fuel (HVOF) flame spraying technique, and microstructure, phase composition and mechanical properties of WC-Cr3C2-12Ni coatings prepared by different oxygen flows were investigated. The results reveal that phase compositions of WC-Cr3C2-12Ni coatings were mainly influenced by the Cr3C2 content rather than the oxygen flow. WC-Cr3C2-12Ni coatings demonstrated low decarburization and decomposition of WC due to coarse WC gains and high in-flight particle velocities during HVOF. WC-Cr3C2-12Ni coatings exhibited low porosities and typical microstructures, where a mixture of fine and coarse WC grains was uniformly embedded in the Ni/Cr3C2 matrix. The microhardness, indentation fracture toughness and elastic modulus of WC-Cr3C2-12Ni coatings were improved by coarse WC grains, Cr3C2 addition and dense microstructure, which resulted in high wear resistances of WC-Cr3C2-12Ni coatings. The abrasive wear features with groove, peel-off and exposed/fractured WC grains were observed in WC-Cr3C2-12Ni coatings after dry-sliding wear. The relationship between microstructure and mechanical property of WC-Cr3C2-12Ni coatings was discussed from the viewpoints of powder properties and process parameters.