Research On The Process And Properties Of Ni-P-ZrO₂ Composite Coating Prepared By Jet-electrodeposition On The Surface Of The Rotor

Jet-electrodeposition has been widely used in many fields because of high deposition rate,fine grain,and excellent surface properties of the coating.Ni-P-ZrO2 composite coating can be used to improve the surface properties of parts due to high hardness,good abrasion resistance and corrosion resistance,and has broad application prospects.At present,there are few studies on Ni-P-ZrO2 composite coating prepared by jet-electrodeposition on the surface of rotor.On the one hand,researches on the preparation of coatings mainly focus on plane and there are few studies on the surface of rotor.On the other hand,the research on the preparation of Ni-P-ZrO2 composite coating is mostly electroless plating or traditional electrodeposition instead of jet-electrodeposition.In this paper,the experiment was conducted on jet-electrodeposition device,the process and properties of Ni-P-ZrO2 composite coating prepared by jet-electrodeposition on the surface of rotor were studied.The main research content is as follows:(1)Multiphysics coupling simulation of jet-electrodeposition machining processes on the surface of rotor.Based on COMSOL Multiphysics,the mathematical model of electroplating secondary,turbulent flow,and dilute mass transfer was established respectively.Then,a coupling model of multiple physical fields was deduced through the interrelationships among the three physical fields.Finally the numerical solution was made.In this paper,the influences of different processing methods(horizontally and vertically placed jet),different jet shapes(conical and straight tube),and different nozzle sizes(1mm×11mm,1.5mm×11mm and 2mm×11mm)on the machining process were studied.The value and uniformity of velocity and current density in the processing gap were compared.Through comprehensive analysis,it is believed that when a conical jet with nozzle size of 1.5mm×11mm is selected and placed in the longitudinal direction,the coating obtained by the test has the best performance.(2)Fundamental experimental study of jet-electrodeposition on the surface of rotor.In this paper,jet-electrodeposition tests on the surface of rotor were performed under the same process parameters by selecting jets of different processing methods,different jet shapes,and different nozzle sizes.The experiment shows that when a conical jet with nozzle size of 1.5mm×11mm was placed vertically during processing,the prepared coating has the best performance by comparing the surface morphology,surface roughness,microhardness,and wear scar width of the coating.lt is consistent with simulation results,the accuracy of the simulation model is verified,and the deficiencies of simulation were made up.(3)Determination of the concentration of ZrO2 particle.Tests were performed based on the previously identified jets and processing methods under the same process conditions.The size of the ZrO2 particles was 50 nm,and the concentrations were Og/L,5g/L,10g/L,15g/L,and 20g/L,respectively.The concentrations of ZrO2 particle were Og/L,5g/L,10g/L,15g/L and 20g/L.The surface morphology,surface roughness,microhardness,and wear scar width of the coating were compared at different particle concentrations.Through comprehensive analysis,the optimal particle concentration was 10 g/L.(4)The research on process test of Ni-P-ZrO2 composite coating by jet-electrodeposition.Experiments were designed by JMP software.Tests were performed based on the previously selected jets,processing methods,and particle concentrations-The mathematical model of each response was established through the step-by-step analysis method and the effects of current,electrolyte velocity,the rotating speed of cathode,and temperature on the microhardness,the thickness,the width of the wear scar,and the surface roughness of coating were studied.It is found that the interaction between the factors is significant,and the effect of one factor on the coating performance will change with the change of another factor.Finally,the best process parameters of jet-electrodeposition Ni-P-ZrO2 composite coating on the surface of rotor were obtained by the expectation function method.It is current of 0.8A,electrolyte velocity of 4.04m/s,the rotating speed of cathode of 7.20r/min,temperature of 64.91?.The properties of the coating prepared under optimal parameters are:microhardness of 703.22 HV,coating thickness of 59.81 ?m,wear scar width of 257.19 ?m,surface roughness of 0.207 ?m.(5)Research on corrosion resistance of Ni-P-ZrO2 composite coating.The polarization curves of Ni-P-ZrO2 composite coating,Ni-P alloy coating and 45 steel substrate at different times were measured by the potentiodynamic sweep method.Then,the corrosion potential,the corrosion current density,and the corrosion rate are obtained by the polarization curve epitaxy method.The test found that the maximum corrosion current density of the 45 steel matrix is about 10 times that of the Ni-P-ZrO2 composite coating,which is about 6 times that of the Ni-P alloy coating.Both Ni-P alloy coating and Ni-P-ZrO2 composite coating have good corrosion resistance.The addition of ZrO2 particles enhances the corrosion resistance of the coating.