Laser deposition of wear-resistant titanium oxynitride/titanium composite coatings on Ti-6Al-4V alloy

Abstract

TiOxNy/Ti composite coatings were deposited on Ti-6Al-4V via laser surface engineering. This process was conducted in the air using TiO2 powder as the starting material. The effect of laser power on the defect, microstructure, chemical composition and mechanical properties of the coatings were systematically investigated. The use of a low laser power resulted in the formation of numerous cracks and pores in the coatings, which reduced considerably with the increased laser power. The predominant phase in the coatings was TiOxNy, a product of the nitridation of titanium oxide in air. The concentrations of O and N in TiOxNy varied with laser power. Ti alloy from the partially melted base metal mixed into the ceramic melt, leading to the formation of α-Ti grains between TiOxNy dendrites. The microhardness and wear resistance of the composite coatings were significantly improved by factors up to 4.7 and 3.9 respectively, compared to the base metal.