Microstructure and Oxidation Behavior of Cr39Ni7C Cermet Coatings Deposited by Diamond Jet Spray Process

摘要

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 compositions, 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 to 150 m/s with the increasing of the spraying distance from 100 to 300 mm, whereas the average temperature of in-flight particles increased from 1926 to 2245 K. The decarburization of Cr{sub}3C{sub}2 increased with the increasing of the fuel gas flow from 58 SLPM to 77 SLPM for higher heat enthalpy of the flame. Due to the formation of Cr{sub}2O{sub}3 on/in the coatings at high temperature, the sprayed coatings had good oxidation resistance at 1073 K in an air atmosphere. The oxidation behavior was found to be governed by the parabolic rate law. For the lower porosity of the coating deposited under the spraying distance of 150 mm, its oxidation resistance saves better than that of the coating sprayed at the spraying distance of 200 mm. A slight reduction of sprayed Cr39Ni7C cermet coating in micro hardness occurred after high temperature at 723 K and 1073 K high-temperature oxidation.