| In recent years,nanomaterials less than 100nm have received extensive attention.Nanomaterials usually exhibit good physical and chemical properties,then in the field of materials nanomaterials have been widely used and become a hot research.?-SiC belongs to cubic system,its Mohs hardness can reach 9.25-9.6 just a little lower than diamond.And?-SiC has high chemical stability,high thermal conductivity,low thermal expansion coefficient and so on.Ni-P-?-SiC composite coating prepared by adding ?-SiC(20nm)into electroplating solution can maintain the corrosion resistance of Ni-P alloy,at the same time it can improve the hardness,the wear resistance of the mechanical parts and then prolong the service life.In this paper,we mainly studied the pulse technology and performance of Ni-P-?-SiC composite coating prepared by jet electrodeposition method.In this paper,Ni-P-?-SiC composite coating was prepared on the Numerical Control device of jet electrodeposition.On the basis of previous studies,the effects of pulse parameters were analyzed and the performance tests were finished.In this paper research works are as followings:(1)The Simulation research on the composite coating Ni-P-?-SiCon COMSOL in jet electrodeposition.COMSOL Multiphysics software was used to simulate and analyze the flow field with different dipolar space and inlet velocity.The coupling analysis of the flow field and the secondary-electrodeposition was carried out in the processing area.The results show that in the condition of dipolar space 1.5mm and the flow rate 3m/s,the distribution of the velocity,pressure and electrolyte potential on the cathode surface are the most suitable.(2)The selection of the surfactant,?-SiC particle concentration and the bath temperature.The single factor experiments were carried out,and it was concluded that SDBS was selected as surfactant by analyzing the polarization curve of plating solution,hardness of Ni-P-?-SiC composite coating and the HLB of different surfactants.The comparison of the micro-hardness,surface roughness and the wear amount of the Ni-P-?-SiC composite coating were analyzed and the concentration of ?-SiC particles should be 4g/L.By comparing the effect of different bath temperature on the deposition rate and micro-hardness of the composite coating,the bath temperature should be 60 ?.(3)Studied on pulse parameter of jet-electrodeposition Ni-P-?-SiC composite coating.The experimental design and the data analysis were achieved by the custom designer module of JMP software.The effects of peak current density,duty ratio and frequency on the deposition rate,the microhardness,the wear amount and the surface roughness were studied.Multiple response optimizations were made according to the corresponding regression equation and the optimal process parameters were:peak current density 73A·dm-2,duty ratio 38%and frequency 1824Hz.Under the pulse condition,the results of the composite coating performance:the average deposition rate 21.34?m·min-1,the microhardness 782.72HV,the wear amount 0.011613 mm3 and the surface roughness 0.054?m.It was shown that the Ni-P-?-SiC composite coating had better wear resistance by comparing with the friction coefficient and wear rate of Ni-P alloy under the optimum process parameters.The phase analysis of Ni-P-?-SiC composite coating under the optimum process parameters showed the presence of ?-SiC.(4)Studied on the corrosion resistance of the composite coating Ni-P-?-SiC prepared by jet-electrodeposition.The corrosion potential and corrosion current of composite coating and alloy coating from the polarization curves obtained by dynamic potential scanning in 50g/L NaCl solutions at different moments.It was concluded that Ni-P-?-SiC composite coating and Ni-P alloy coating have excellent corrosion resistance.At the same time,the corrosion mechanism was analyzed. |
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