Research On Laser Preparation And Performance Of Copper Cladding On Steel Substrate

In recent years,the price of copper continues to rise,resulting in higher and higher production costs of copper products.In this paper,the pure copper coating with high bonding strength and stable microstructure and properties was prepared on the surface of45 steel by laser cladding technology.On this basis,the strength of the pure copper coating was further improved by adding ceramic reinforcing phase VC,so that it could be applied in high demand service environment.Relying on the laser cladding technology,the steel-copper composite material not only has the excellent properties of copper anti-corrosion and anti-wear,but also saves copper and reduces the production cost.First of all,a complete orthogonal experimental scheme was designed to optimize the laser process parameters.The surface morphology and the porosity of the pure copper cladding were compared,found that when the laser power was 3200 W,the scanning speed was 430 mm/min,and the synchronization was 50g/min the layer surface quality was best and the porosity was lowest.,so this parameter was adapted to prepare specimens and analyze the results.The results show that the structure of the cladding layer is equiaxed,the dilution rate between steel and copper is low,the wettability is poor,and the pores are concentrated on the bonding interface and above the bonding interface.And the microhardness of the pure copper coating is 90.3HV,which is significantly lower than the base material,and the strength is poor.Then,two methods were used to improve the bonding performance between steel and copper,and the microstructure and properties were analyzed.The first method was to add the transition layer.The results show that the preparation of defect-free coating is achieved when adding the transition layer of NJ30 and JG-1,and the microstructure of the pure copper coating is different with the different transition layer materials.The second method was the method of applying ultrasonic vibration with a frequency of 40 k Hz.The results show that the grain size of pure copper coating is refined due to the effect of cavitation after ultrasonic vibration.However,there are still porosity defects in the bonding interface,which fails to achieve the purpose of preparing pure copper coating without defects.Both methods improve the properties of the copper coating,especially when the NJ30 transition layer is added,the microhardness of the copper coating reaches 114 HV.Finally,on the basis of adding NJ30 transition layer,the strength of pure copper coating was further improved.Three kinds of pure copper-based VC composite powders with VC content of 0.5%,1%,and 2% were designed.The microstructure,microhardness,and wear resistance of the coating were compared.The results show that crack defects are prone to occur when the content of VC is too high.When the content is 0.5%,the obtained microstructure grains are uniform,and the microhardness of pure copper cladding reaches249.2 HV,the strength is significantly improved,at the same time,the friction coefficient is 0.297,which makes pure copper cladding surface have good wear resistance.