Multi-Objective Optimization of Pulse Electrodeposition Process and Properties of Ni-Mo Coatings on the Surface of H62 Copper Alloy Based on the Integration of Response Surface Methodology and Genetic Algorithm

Copper alloys are widely used in the field of equipment manufacturing due to their excellent electrical conductivity，thermal conductivity，and processability.However，their inherent drawbacks of low hardness and poor wear resistance render them susceptible to failure in electrical contact applications.Ni-Mo alloy coatings，which exhibit a combination of high hardness，excellent corrosion resistance，and hightemperature stability，are an ideal solution for surface strengthening of copper alloys，and pulse electrodeposition parameters (duty cycle，current density，frequency) exert a crucial influence on the properties of Ni-Mo coatings.Traditional experimental optimization methods are costly and inefficient，and it is difficult to balance the competitive relationships among multiple performance indicators.Therefore，this study adopted response surface methodology (RSM) combined with genetic algorithm (GA) to perform multi-objective optimization of the pulse electrodeposition process of Ni-Mo coatings on H62 copper alloy surface，aiming to obtain the process parameter combination with optimal comprehensive performance.Taking duty cycle (10%－50%)，current density (2－4 A/dm2)，and frequency (100－500 Hz) as independent variables，and the microhardness，steady-state friction coefficient，wear rate，self-corrosion current density，and charge transfer resistance of the coating as response values，this study designed 15 experimental schemes based on the Box-Behnken design.The structure and properties of the coatings were systematically characterized using X-ray diffraction (XRD)，field emission scanning electron microscopy (FE-SEM)，a microhardness tester，a reciprocating friction and wear tester，and an electrochemical workstation.The results showed that a low duty cycle favored the formation of fine-grained structures，thereby significantly enhancing the coating hardness (up to 533 HV0.05).A significant trade-off relationship existed between the wear resistance and corrosion resistance of the coatings.Based on the response surface model，the contribution degree of each parameter was quantified: the contribution ratios of duty cycle to microhardness，steady-state friction coefficient，and wear rate were determined to be 66.21%，61.79%，and 84.46%，respectively；the contribution ratio of frequency to self-corrosion current density was 38.83%；and the contribution ratio of duty cycle to charge transfer resistance was 59.35%.The genetic algorithm (GA) was employed to obtain the Pareto optimal solution set，and the optimal process parameters were determined through weighted decision-making as follows: duty cycle 10%，current density 4 A/dm2，and frequency 460 Hz.The optimized coating formed a fine-grained and high-molybdenum composite structure with a molybdenum content of 16.69%，and its comprehensive performance was significantly improved: the microhardness was 471.287 HV0.05，the steady-state friction coefficient was reduced to 0.264，the wear rate was as low as 2.985 0×10－5 mm3/(N·m)，the self-corrosion current density was 1.734 0×10－6 A/cm2，and the charge transfer resistance was 7 748 Ω·cm2.In comparison with the optimal group from the response surface experiments (duty cycle 10%，current density 3 A/dm2，frequency 500 Hz)，the steady-state friction coefficient of the optimized group decreased by 4%，the wear rate decreased by 0.64%，and the self-corrosion current density decreased by 6.93%.With a minor reduction in hardness (3.48%)，both wear resistance and corrosion resistance were improved concurrently.The integration of RSM and GA effectively addressed the multi-parameter and multi-objective optimization challenge associated with the pulse electrodeposition process，quantified the mechanism underlying the influence of parameter interactions on coating properties，and provided a scientific basis and technical support for the process optimization of Ni-Mo coatings on copper alloy surfaces.It is of great significance for improving the surface performance of copper alloy materials and expanding their application scenarios.