Cladding Technology And Modification Of Ni60+CeO₂ Coating On 6061 Aluminum Alloy By Electron Beam Cladding

6061 aluminum alloy is widely used in automotive and aircraft key parts because of its lightweight structure.Nevertheless,the surface hardness,wear resistance and corrosion resistance of 6061 aluminum alloy are poor under the condition of high strength for a long time.The surface modification of 6061 aluminum alloy by electron beam cladding technology has become one of the current popular research.In this paper,Ni60+CeO₂ composite coating is cladding on 6061 aluminum alloy surface.Aiming at the difficulty of electron beam cladding process of aluminum alloy with low melting point,The temperature field during electron beam processing is simulated by the means of Finite element numerical simulation,which aims to study the distribution law from temperature field at different preset coating thicknesses and different process parameters.The experiment of rare earth CeO₂ regulating cladding was carried out with the optimized technological parameters,and the action mechanism of CeO₂ in cladding layer was studied.Firstly,a composite powder ratio model was established,and the mass ratio of CeO₂powder was determined by introducing the filling coefficient K.Experimental analysis showed that CeO₂ particles existed in the composite coating in the form of monodispersity,which verified the reliability of the ratio model.Secondly,the temperature field model of cladding was developed to utilize simulation to analyze the impact of preset coating thickness and process on the the temperature field.The results exhibit that the peak temperature of the same node located on the cladding surface as well as the depth and width of the molten pool raised in the wake of the increase of the preset coating thickness,but on the contrary is the decline substrate melting depth.Combined with the experimental results,it is found that the cladding layer with prefabricated coating thickness of 1mm has the best formation quality.Process parameters:in the wake of the addition of scanning power,the pool depth and width of the cladding layer increase.As scanning speed and beam spot diameter incresed,the pool depth and width of the cladding layer degraded.Simulation analysis determined that the best simulation dilution rate of cladding layer was 0.2936,scanning power was 1500W,beam spot diameter was 6mm and scanning speed was 10mm/s.Again,through to the cladding layer section,SEM,EDS and XRD analysis found that adding 4%best Ni60 cladding layer morphology of CeO₂,its surface density,level off is smooth,no cracks,porosity and potholes in defects,microstructure is mainly composed of some thin branches crystal,crystal spacing is small,compact structure,combining zone after adding rare earth element diffusion,Compared with Ni60,Ni60+5%CeO₂ and Ni60+6%CeO₂ cladding layer,the brittle phase of（Al Si）₇Ni₃ disappears,which reduces the fracture tendency of the cladding layer.Finally,the performance of cladding layer have been tested and compared with each other.The hardness of Ni60+4%CeO₂ cladding layer of cross section is the top,which is14.4 times that of the matrix.The wear resistance of Ni60+4%CeO₂ cladding layer is highest one among aluminum alloy substrates,Ni60 and other rare earth CeO₂ content clad layers.The order of acid and salt corrosion resistance of the cladding layer is as follows:Ni60+4%CeO₂ cladding layer>Ni60 cladding layer>6061 aluminum alloy.It is proved that proper amount of CeO₂ can improve the properties of cladding layer.