Laser cladded TiO2–Cu composite coatings with high TiO2 content: Tribological properties by first-principle calculation

Abstract

TiO2–Cu composite coatings with high TiO2 content were fabricated on Ti6Al4V alloy by laser cladding to improve its tribological properties in bioengineering field. The effects of TiO2 mass fraction on the microstructure and chemical compositions of obtained composite coatings were investigated using a scanning electron microscope and energy dispersive spectrometer, respectively, and the surface hardness was measured via a Vickers microhardness tester. The coefficients of friction and wear rates of TiO2–Cu coatings were investigated using a ball–on–disc wear tester against the tribo–pair of Si3N4 ball, and the wear mechanism was investigated using the first-principle calculation. The results show that the TiO2–Cu composite coatings are mainly composed of Cu4Ti3, TiO2 and Cu phases, in which the TiO2 plays the roles in friction reduction and wear resistance. The average COFs and wear rates of 90%TiO2–Cu composite coating are the lowest among the three types of TiO2–Cu composite coatings, which is attributed to the TiO2 solid lubricant and anti–wear effects. The wear mechanism is dominated by abrasive wear with slight adhesive wear, in which the two–body wear is increased with the increase of TiO2 mass fraction.