THE EROSION-OXIDATION BEHAVIOR OF HVOF CR3C2-NICR CERMET COATING

DenSys DS-200 coating is a proprietary hypersonic velocity oxygen fuel (HVOF) CrC2-NiCr cermet coating used in elevated temperature service environments including fluidized bed boilers, coal-fired boilers and m unicipal waste incinerators. The elevated temperature erosion-corrosio n (oxidation) behavior of this HVOF Cr3C2-NiCr coating was investigate d using a range of test temperatures, impact angles, erodents and part icle velocities. The erosion-corrosion behavior of HVOF Cr3C2-NiCr coa tings was compared with those of 1018 steel and other thermal-spray co atings including FeCrSiB (Armacor M), Ni-base, Cr2O3-6SiO2-4Al2O3 (Rok ide C), Cr2O3-12SiO2-2Al2O3-4MgO (Rokide MBC) and WC-NiCrCo (SMI 712). It was found that the erosion-oxidation resistance of HVOF Cr3C2-NiCr coating was higher than those of 1018 steel and other coatings at imp act angles of 30-degrees and 90-degrees. The erosion-oxidation behavio r of coatings was well related to their morphology. The high erosion-o xidation resistance of the HVOF Cr3C2-NiCr coating was attributed to i ts low porosity, fine grain structure and homogeneous distribution of hard carbides/oxides which form a skeletal network within a ductile an d corrosion-resistant metal binder.