STRUCTURAL, TRIBOLOGICAL, AND CORROSION PROPERTIES OF CR₃C₂–NICR COATINGS DEPOSITED BY THE HVOF METHOD

This study is aimed at extending the service life of 12Kh1MF steel boiler tubes used in thermal power plants. Cr₃C₂–NiCr coatings were deposited by the high-velocity oxygen–fuel (HVOF) spraying method, and their structural–phase, mechanical, tribological, and corrosion properties were investigated. It was found that preheating the substrates at different temperatures (without preheating, 100 °C, and 200 °C) significantly affects the coating morphology, porosity, and mechanical characteristics. SEM analysis revealed that the coatings exhibit low porosity, while XRD results confirmed the stability of the Cr₃C₂ phase and the ability of the NiCr matrix to effectively bind the carbide particles. This prevents coating spallation and ensures phase stability at elevated temperatures. The coatings obtained at a preheating temperature of 100 °C demonstrated the best overall performance: hardness increased up to 897.8 HV, surface roughness decreased, the coefficient of friction stabilized, and the wear track diameter reached its minimum value (712 µm). In addition, a reduced corrosion rate was observed. Overall, the results demonstrate that Cr₃C₂–NiCr coatings are effective protective layers with high strength, wear resistance, and corrosion resistance, making them suitable for application in high-temperature aggressive environments.

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