Resurfacing the exhaust valve by plasma spraying versus electric arc and gas flame methods

Abstract

In modern conditions of economic instability in various sectors of industry for the national economic complex, it is important to improve the technology for repairing parts of power units, while the development of modern technological methods for restoring the contact surfaces of parts should be carried out in the conditions of enterprises and be accessible. The article compares the most common methods of surface parts restoration, such as flame, plasma spraying and electric arc surfacing. Studied experience of various specialists working in this direction made it possible to implement these reduction methods using a charge based on a mineral tungsten-containing concentrate, boron and carbon. The process of alloying the resulting coatings was investigated, where tungsten is in the form of tungsten trioxide (WO3) and calcium tungstate (CaWO4). A comparative analysis of the methods for restoring the surface of the exhaust valve cone of the D49 diesel engine has been carried out. The article presents results of microand macroanalysis of the structures of the obtained coatings and the base metal of the restored part, the results of the analysis of the chemical composition, the evaluation of the microhardness and adhesive strength of the adhesion of the obtained coatings to the surface of the base metal. Authors substantiated the prospect of applying the methods of gas-thermal restoration of the surface of parts in relation to the method of electric arc surfacing. Subsequent studies will focus on the installation of remanufactured parts in the internal combustion engine of the locomotive, their operation in real conditions, and the assessment of reliability and durability. Research in this direction will improve the quality indicators of the restored surfaces of power unit parts of rolling stock.