Influence of niobium ion implantation on the microstructure, mechanical and tribological properties of TiAlN/CrN nano-multilayer coatings

Abstract

In this paper, TiAlN/CrN nano-multilayer coatings were deposited on the substrates of cemented carbide (WC–TiC–Co) using magnetic filtered arc ion plating (MFAIP) method and implanted with niobium ions at 40kV with the doses of 5×1016, 1×1017 and 2×1017ions/cm2 by metal vacuum vapor arc (MEVVA) ion source. The microstructure and chemical compositions of Nb-implanted coatings were investigated by high-resolution transmission electron microscopy (HRTEM), grazing incidence X-ray diffraction (GIXRD) and X-ray photoelectron spectroscopy (XPS). Meanwhile, the mechanical behavior of coatings was analyzed by nano-indentation test and the tribological properties were investigated on a ball-on-disc friction and wear tester.Nb ion irradiation induced amorphization and the formation of nanocomposite and nanocrystalline in the coatings surface. Nb ion implantation resulted in the formation of NbN, Nb2O5 and a small fraction of niobium oxynitride in the implanted zone. The nanohardness and the H3/E*2 ratio of the coatings increased remarkably, which was due to the resulting structure and the formation of NbN phases in the implanted zone caused by energetic Nb ion implantation. Nb ion implantation could effectively improve the tribological performance of TiAlN/CrN coatings, which was due to a lower friction coefficient and the increasing of the hardness and the plastic deformation resistance of the coatings. The amorphous top layer formed on the surface could act as a solid lubricant during the wear sliding.