A study of Cr₃C₂-based HVOF- and HVAF-sprayed coatings: Abrasion, dry particle erosion and cavitation erosion resistance

Material and spray process selection are the key factors in the tailoring of thermal sprayed coatings for demanding industrial applications. In this study, four commercial Cr₃C₂-based feedstock materials were sprayed with gas-fuelled high-velocity oxygen-fuel (HVOF) and modern high-velocity air-fuel (HVAF) spray processes. Two materials with standard Cr₃C₂–25NiCr composition (porous and dense), a Cr₃C₂–50NiCrMoNb and Cr₃C₂–37WC–18NiCoCr materials were sprayed in addition to the reference WC-10Co4Cr material. The Cr₃C₂–50NiCrMoNb had a higher content of the Ni-based metal matrix compared to standard Cr₃C₂–25NiCr composition for added corrosion resistance, while the Cr₃C₂–37WC–18NiCoCr material contained additional tungsten carbide (WC) particles to improve the wear resistance. In abrasion and dry particle erosion, the Cr₃C₂–50NiCrMoNb coatings showed a higher degree of plastic deformation and increased material loss, whereas the Cr₃C₂–37WC–18NiCoCr coating had wear resistance between the standard Cr₃C₂–25NiCr and reference WC-10Co4Cr coatings. In cavitation erosion, the lower carbide content of Cr₃C₂–50NiCrMoNb coatings turned out to improve the resistance against fatigue wear due to higher fracture toughness. Overall, the HVAF sprayed coatings had higher elastic modulus, higher fracture toughness, equal or higher abrasion and erosion resistance, and higher cavitation erosion resistance compared to the HVOF sprayed counterparts.