Vigilyanska N. Electric arc spraying of composite copper-based coatings with pseudoalloy structure.

The thesis is devoted to the study of the process of coatings formation with a pseudoalloy structure in the conditions of electric arc spraying (EAS) using dissimilar wire materials. The studies were carried out using Cu-Fe, Cu-Al, Cu-Mo systems which have different types of interphase interaction of the components. Method of mathematical planning of the experiment was used to study the character of the relationship between the spraying conditions and the process of pseudoalloy coatings formation. The regularities of the change in the dispersion of the products of dissimilar wires atomization depending on the EAS modes were established. The degree of influence of the spraying parameters on the structure and properties of pseudoalloy coatings was determined. It was established that during the transfer of the atomization products of Cu and Fe, Cu and Al wires to the substrate interphase interaction of molten droplets occurs with the formation of particles of a pseudoalloy structure. Coatings of Cu-Fe, Cu-Al, Cu-Mo with a pseudoalloy structure were obtained as a result of EAS of dissimilar wires. It was found that the relative copper content in the Cu-Fe coatings is decreased due to its evaporation as a result of spraying with heat input in the wire of 1.5–2.2 MJ/kg. During the formation of the Cu-Al coating layer the appearance of the interaction products of copper and aluminum with the formation of intermetallic phases is observed. The basic principles of EAS technology for production of the coatings with a pseudoalloy structure were developed. Approaches to the choice of compositions of pseudoalloy coatings for various functional purposes were proposed. Based on the experiments of the of pseudoalloy coatings Cu-NiCr, Cu-flux-cored wire (FCW(Fe-FeB)) and the results of the study of its properties the developed coatings are recommended for application in order to increase the resistance of the walls of molds for continuous casting machines. The developed Cu-FCW(Fe-FeB) coatings are successfully used to increase the service life of the friction discs of the excavator gearbox.