Research On Metal Based Diamond Composite Coating Prepared By Laser Cladding-laser Melt Injection

Laser cladding and laser melt injection technologies were used to produce the diamond intensified wear resistant composite coatings on the medium carbon steel?45#?by means of varying the size of diamond and bonding matrix powder.The feasibility of preparing the diamond composite coatings by using the laser cladding and laser melt injection had been discussed in this work.Laser cladding and laser melt injection processes were carried by changing laser energy density and sizes of diamond particles.The advantages and disadvantages of two methods were compared.And the optimal parameters were also obtained.The microstructure of composite coatings and bonding strength between the diamond and matrix were analyzed by scanning electron microscopy?SEM?,energy dispersive spectroscopy?EDS?and X-ray diffraction?XRD?,respectively.The wear resistance and corrosion resistance of the composite coatings were tested by friction and wear tester and electrochemical workstation,respectively.The results show that the laser melt injection is more suitable for preparing composite coating containing non-phase change diamond particles.However,in the laser cladding process,the diamond particles seriously turn into the graphite or are burnt.But diamond has different degree of carbonization with laser energy density and diamond sizes change in the laser melt injection.Diamond carbonizes and dissolves into the substrate to form cementite with high laser energy,and retains the original phase in the coating with lower laser energy.The amount of diamond particles reaches the peaks under the optimal parameters,and the diamond particles are integrity with edges and corners distinct.The results of phase analyses show that the iron-based diamond composite coating consists of strengthening phase Fe_0.64Ni_0.36,supersaturated solid solution Cr,carbide Fe_xC_y and Mn₅C_2,and graphite?diamond?.Nickel-based diamond composite coating consists of strengthening phase FeNi₃,carbide Mn₂₃C₆ and graphite?diamond?.Laser melt injection diamond composite coating consists of graphite?diamond?,?-Fe,cementite and CrSi₂.The wear resistance of diamond composite coating produced by laser cladding is better than that of the coating without diamond.The wear resistance of iron-based diamond composite coating increases by 60%,and the wear mechanism of the coating is abrasion wear primarily,as well as oxidation wear and a little adhesion wear.The wear resistance of nickel-based diamond composite coatings increases by 30%.And the wear mechanism of the coating is adhesion wear and mildly oxidation wear.The wear resistance of diamond composite coating produced by laser melt injection increases by30%than that of the substrate.The wear resistance of the coating is primarily of abrasion wear,a little adhesion wear and oxidation wear.The corrosion resistance of diamond composite coating produced by laser melt injection is raised one order of magnitude.