The Influence of the Cooling Mode During High-Speed Thermal Spraying of Coatings Made of 95Cr18 Steel on Their Structure and Wear Resistance

A study was carried out of the influence of the cooling rate of gas-thermal coatings made of high-chromium steel 95Cr18 on their phase composition and tribotechnical properties. It has been established that preheating the steel substrate to 400 °C before spraying the coating leads to a 2.7 fold decrease in its cooling rate in the region of bainite transformation and an increase in the content of retained austenite in the coating to 83.5 vol. %. It is shown that the stabilization of austenite is due to the redistribution of carbon between the α and γ phases and the enrichment of austenite with carbon. It has been established that a coating made of steel 95Cr18, sprayed onto a substrate heated to 400 °C, is characterized by higher wear resistance under various friction conditions (by 12—24 %) compared to a coating formed on a cold substrate. High wear resistance of coatings with a high content of the γ-phase is achieved due to the deformation-activated γ→α transformation, leading to a significant increase in microhardness and wear resistance of the surface layers of coatings.

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