Structure and tribological properties of super-hardened strengthening coatings based on boron carbide

Abstract

The use of standard alloys, in particular steels, to increase the wear resistance of contact surfaces in mechanical engineering in most cases has lost its relevance due to low mechanical and tribological properties. Currently, in mechanical engineering, as well as in repair production, technologies for obtaining functional and restorative coatings that differ significantly from the properties of the product material are widely implemented. (Research purpose) The research purpose is in studying the physical and tribological properties of ceramic coatings obtained by laser melting of fine powder materials. (Materials and methods) Authors used a powder mixture based on boron carbide and nitride as the initial powder materials as the most solid, heat-resistant and chemically inert compounds, additionally doped with magnesium oxide and lithium. Authors used an ytterbium fiber laser with a maximum power of 50 watts as a laser radiation generator. (Results and discussion) It was found that laboratory studies confirm the high adhesion of the ceramic coating with a steel substrate. It also was found that stable chemical compounds based on iron carbides and borides are formed in the fusion zone. The article notes that the high impact strength of the coating was confirmed by the shock tests of samples-in the impact (destruction) zone, there is no formation of significant cracks and chips of the coating, the fusion zone without traces of separation and destruction. The article shows that the lowest coefficient of friction at elevated temperature and dynamic loads is observed in coatings with the presence of metal oxides, this is explained by the accelerated formation of a tribofilm based on boric acid. (Conclusions) The presented results have a high scientific basis and practical potential. The low coefficient of friction and high wear resistance allow to use the results of research in tribo-couplings that are operated under high temperatures and kinematic characteristics.