Influence of Modifying Nanoadditives on the Properties of a Multilayer Composite Coating Obtained by Laser Surfacing

Resumo

This paper presents the results of an experimental investigation of the influence of modifying nanoadditives on the structure and mechanical properties of multilayer coatings obtained by the laser surfacing of a composite powder with a strengthening phase. The powder of a nickel-based Ni–Cr–B–Si–Fe self-fluxing alloy with a strengthening phase of tungsten carbide was used as the surfacing material; and a mixture of nanosized refractory powders of titanium nitride and yttrium oxide clad with iron and chromium was used as the modifying additive. It has been established that the surfaced coating represents a complex system of phases formed in the process of melting and interaction of chemical elements of the substrate and of the surfaced powder mixture. The main component of the coating is the compound of nickel with iron of an Ni₃(Fe, Cr) type. A partial dissolution of the strengthening phase occurs in the melting process depending on the concentration of the nanomodifier. In the case under consideration, the optimal amount of the modifying additive, which provides a maximum increase in the hardness and wear resistance of the composite coatings of the Ni–Cr–B–Si–Fe/WC system, is 0.1 wt % refractory TiN + Y₂O₃ nanopowders in the composite material.