Research On Fabrication Of The Anti-Wear Gradient Surface Coating And Its Sliding Friction Property

RESEARCH ON FABRICATION OF THE ANTI-WEARGRADIENT SURFACE COATING AND ITSSLIDING FRICTION PROPERTYABSTRACTSurface coating is one of the important methods to improve the metal properties in the area of material surface engineering. Ceramic coatings of transition metal nitrides are extensively used to fulfill the requirements of the enhanced wear resistance for many applications of surface engineering. For example, TiN coating is extensively used as a protective layer for tools owing to its excellent wear and corrosion resistance in industrial applications. In order to improve its properties of TiN coating further, multi-layer coatings, multi-component coatings and gradient layer coatings have been investigated.A series of multi-component (Ti.Me) N coatings were deposited using by multi-arc ion plating on the surface of HSS substrate in this paper. The effects of different metal elements on the phase composition and properties of the coatings had been investigated systematically. Multi-component (Ti,Me) N gradient coatings were prepared according to the compatibility between physical properties of coating material and substrate on the basis of (Ti,Me) N homogenous coatings. Design rules of multi-component gradient coating were discussed. A new experimental method and quantitative evaluation rules of fracture toughness of coating were provided. The sliding wear properties of (Ti,Me)N coatings were studied. The pre-nitriding(Ti,Me)N coating and post-treatment (Ti.Me) N coating using high-energy ion bombardment process were performed. The innovative work and relative results were concluded in this paper as follows:1. A series of TiN-based multi-component TixNb|_xN coating, TixZr,_xN coating, TixCri _XN coating, TixTa,_xN coating were deposited on the surface of HSS substrate using by multi-arc ion plating process in this paper.(1) Phase compositions of multi-component TixMe,_xN coatings were investigated. It can be mainly divided into two kinds. One is that there is single phase in the multi-component coatings. Another is that mixed phases of TiN phase and MeN phase co-existed in the same coatings.(2) The component compositions and phase structures had been analyzed theoretically through comparing with thermo-dynamics, atomic radii of metal elements and the crystal structure of metal nitride coatings, etc. The relationship between additive metal elements and phase compositions of the multi-component coatings was discussed.(3) The phase compositions of the multi-component coatings reported in other literature can be explained with the above theory. The phase compositions and their properties of various multi-component coatings can be estimated.(4) The phase compositions of the TiN-based multi-component TixMe,.xN coatings reported in other literatures were explained with the above theory. The phase compositions andtheir properties of multi-component Me (C,N,B---) coatings can be estimated.(5) The phase compositions and its micro-hardness of the TiN-base multi-component (Mel,Me2) N coatings were predicted with the above theory. This can be ijsed in studying and developing hard coatings.2. Multi-component TixNb,_xN and TixZr,'_"xN gradient coatings were performed according to the compatibility between physical properties of-coatingf material and substrate on the basis of (Ti,Me) N homogenous coatings. Their modulated composition, phase structure and properties were investigated. Multi-component fFijNbvixN gradient coating possessed maximum micro-hardness and better fracture toughness. On the contrary, the mechanical properties of multi-component TixZr!_xN gradient coating has ttofany '"obvious1 improvement.3. Cohesion between coating and subslriate was 'generally-conducted by spherical indentation test. A simple method to qualitatively measure ffacture toughness of coating was carried out through Vicker's indentation. It is the First time that a ne\v method to evaluate fracture toughness of the coating firstly provided by combining 'craelo-density function p with spheri...