Structure and properties of coatings obtained by gas-thermal spraying

The authors investigated the microstructure and mechanical properties of wear-resistant coatings applied by the method of gas-thermal spraying with heating of the metal to a liquid state and its subsequent spraying with a gas jet. Nowadays, thermal spraying is increasingly an alternative to various methods of surfacing due to the high costs of consumables, the complexity of maintenance and safety during repairs. By this method, it is possible to reliably solve a variety of technological tasks, which include spraying of wear-resistant, antifriction and corrosion-resistant coatings; alitizing by spraying (increasing heat resistance); increasing the size of products; surfacing and soldering; elimination of casting defects; manufacture of molds, etc. The tribotechnical properties of the vibration damper rod of a railway carriage with reinforcing surface layers applied to the working surface by methods of gas-thermal spraying with 40Kh13 steel and galvanic chromium plating were investigated. Structure and thickness of the coatings, microhardness distribution in the coating-substrate zone, as well as the features of the coatings destruction under the same test conditions were studied. The criterion for comparing the coatings’ wear resistance was the operating time of the samples before the beginning of the coating destruction. Wear of the rollers was determined by the change in diameter, and wear of the pads – by the depth and width of the grooves formed on their surface during the experiment. The coating applied to the vibration damper rod by spraying 40Kh13 steel wire has high wear resistance in conditions of boundary friction with grease and can be an alternative to electroplated chrome coating. The high wear resistance of the coating makes it possible to recommend it for restoring the dimensions of worn parts and increasing the durability of new ones, as well as for replacing special anti-friction bearing alloys.