Friction Treatment of a Plasma Layered Ni + WC–12 wt % Co + Ni + WC–12 wt % Co + Ni Coating on a Cylindrical Titanium Substrate

Abstract

The microstructure and microhardness of a Ni + WC–12 wt % Co + Ni + WC–12 wt % Co + Ni plasma-enhanced layered coating on a cylindrical titanium substrate after friction treatment (FT) with simultaneous pressure by two high-speed steel tools has been analyzed. The experiments were performed with substrate rotation and tool movement along the generatrix of the substrate. The main FT parameters, that is, the linear velocity of the coating during its rotation and the shear force of tools on the coating, determine the power of the process of up to 0.77 kW. This work on the coating, as related to its area of 34 J/mm², determines the process temperature of up to 1391°C. Local deformation of the coating during FT on substrates with smooth and threaded surface profiles with a height of 89–371 μm compacts the coating to a greater extent in its upper part and above the ridges. The microhardness of the layer (WC–12 wt % Co) of the coating in the state after plasma spraying with an indenter load of 200 G was 6.91 GPa and 12.09 GPa at P = 20 G; after FT the microhardness increased to 18.92 GPa with an indenter load of 200 G and to 21.56 GPa with a load of 20 G, which corresponds to the microhardness of the sprayed powder.