Experimental Study On Technique Of Jet-electrodepositing Ni-P Alloy Coating On Micropit Array Surface

In this paper,jet electrodeposition technology is combined with surface micro-texture technology and a design idea of coating surface which combines micro-texture with Ni-P alloy coating is proposed.Micro-texture is used to endow metal surface with special features.Well-regulated micropit texture on the surface of friction pair is effective on the storage of oil and wear debris,which improves the frictional wear property of friction pair surface.Besides,Ni-P alloy coating performs well in many characteristics such as microhardness?surface quality?wear-resistance and corrosion resistance,which can be applied in many fields.On the basis of investigation on surface micro-texture technology,ECM method was used in preparing array micropit on the 45 substrate surface.Then Ni-P alloy coating was deposited on the micropit array surface by jet-electrodeposition.The microstructure,corrosion resistance and binding ability of the resulting composite coatings were investigated systematically.The main contents of the study are as follows:(1)Finite element simulation of jet lithography electrolytic machining was carried out.After the designing of different kinds of cathode nozzle structures,including taper and rectilinear figure,and establish of turbulence model,flow field was simulated and analyzed in COMSOL Multiphysics.Then,trail test on jet lithography electrolytic machining using different nozzles was executed.According to the contrast of tests and simulation results,a better flow field generated by rectilinear nozzle was determined.What's more,micropit forming electric fields were mimicked in the mathematic model of electric field and deformation geometry physics field,which utilized rectilinear nozzle.In the simulation,effects of different parameters such as processing voltage,machining gap,cathode moving velocity were researched.Analysis result exhibited the range of various parameters:voltage from 5V to 15V,gap from 200?m to 1000?m,cathode moving velocity from 60mm/min to 120mm/min.A series of simulations on mask holes of different diameters were carried out.Results showed that with the amplification of mask diameters,lateral corrosion decreased gradually.(2)Micropit array jet lithography electrolytic machining experiments was carried out.In single factor experiment,effects of processing voltage,cathode moving velocity,processing gaps on several factors including diameter,depth and bottom contour roughness of micropit respectively.Afterwards,an ideal technique parameter group was obtained:processing voltage of 12V,processing gap of 200?m,cathode moving velocity of 60mm/min.What's more,influences of jet lithography electrolytic machining scheme on processing quality of mask holes in different diameters were investigated.With the help of data analysis,a conclusion that processing quality of mask holes in 200?m performed better than that of holes in 100?m and 150?m can be drawn.(3)Jet-electrodepositing Ni-P alloy on micropit array surface experiments were studied.In this work,effects of current and flow velocity on micropit coating properties were investigated.According to integrated contrastive analysis on coating surface morphology,roughness and substrate binding force,an deal set of technique parameters can be obtained:current of 0.6A,flow velocity of 4m/s,jet gap of 2mm,plating solution temperature of 60?,anode scanning velocity of 1000mm/min.Surface of micropit array Ni-P alloy coating prepared in this group of parameters could be more compact and showed an obvious improvement on binding force compared with common complanate Ni-P alloy coating.Based on optimized parameters,four kinds of micropit array with different depths and good roughness were investigated.Effects of different pit depths on surface morphology,roughness and binding force of micropit array Ni-P alloy coating were analyzed.Investigation showed that Ni-P alloy coating deposited on micropit array with average diameter of 232.2?m and average depth 30.7?m performed best general property.(4)Frictional wear property of micropit array Ni-P alloy coating was investigated.In the same experimental parameter,frictional wear properties of 45 substrate,45 micropit array,complanate Ni-P alloy coating,micropit array Ni-P alloy coating were contrastive analyzed.Based on experiments,friction coefficient values were compared:friction coefficient of 45 substrate>that of 45 micropit array>that of complanate Ni-P alloy coating>that of micropit array Ni-P alloy coating.In addition,grinding crack widths were compared and a same law could be obtained.Results showed that micropit array Ni-P alloy coating showed a best frictional wear property compared with another test specimen.