Microstructures and Oxidation Behavior of Cr39Ni7C Cermet Coatings Oeposited by Diamond Jet Spray Process

For the promising erosion and oxidation resistance of carbide cermet coating, Cr39Ni7C cermet coatings were deposited by Diamond Jet spray process using a commercial Sulzer Metco 5241 powder in this study. The microstructure, phase composition and high temperature oxidation behavior of the deposited coatings were investigated. The speed and temperature of in-flight particles were measured by DPV-2000. The results revealed that the speed of in-flight particles decreased from 229 m/s to 150 m/s with the increasing of spraying distance from 100 mm to 300 mm, whereas the average temperature of in-flight particles increased from 1926 to 2245 K. The decarburization of Cr₃C₂ increased with the increasing of fuel gas flow from 30 FMR to 40 FMR for higher heat enthalpy of flame. Due to the formation of Cr₂O₃ on/in the coatings at high temperature, the sprayed coatings had good oxidation resistance at 1073 K in air atmosphere. For the lower porosity of the coating deposited under the spraying distance of 150 mm, its oxidation resistance was better than that sprayed under the spraying distance of 200 mm.