A study on high temperature oxidation behavior of high-velocity arc sprayed Fe-based coatings

FeCrNiNbBSiW and FeCrNiNbBSiMo coatings were deposited on AISI 20 steel by high-velocity arc spraying (HVAS). The high-temperature oxidation behaviors of FeCrNiNbBSiW coating and FeCrNiNbBSiMo coating were investigated in an atmospheric environment. The microstructure, surface morphology and chemical compositions of the coating were investigated by means of optical microscopy, scanning electron microscopy, energy-dispersive spectroscope and X-ray diffraction, respectively. The results indicated that the FeCrNiNbBSiW coating had better high-temperature oxidation resistance than did the FeCrNiNbBSiMo coating. This result was observed primarily because the FeCrNiNbBSiW coating had a compacter structure, lower porosity, and more fattened and less splashed surface than did the FeCrNiNbBSiMo coating. The oxidation products of the coatings depended on the oxidation temperature. When the temperature increased from 550 °C to 650 °C, the oxidation product of the coatings transformed from FeO·(Fe,Cr)2O3 and (Fe,Cr)2O3 to (Fe,Cr)2O3 and Cr2O3.