Optimization of Electroless Ni–B Coating Deposition Parameters by Response Surface Methodology for Enhanced Corrosion Resistance

In this study, we attempted to use the response surface methodology with temperature, pH and thiourea concentration as control variables by systematically varying the experimental parameters in order to find the optimal preparation process for electroless deposition of Ni-B coatings. A mathematical model of the effect of different experimental parameters on the impedance of Ni-B coating was constructed by selecting the Box–Behnken Design (BBD) design, and the optimum plating solution temperature, pH and thiourea concentration for electroless deposition of Ni-B coating were discussed through optimization analysis. The surface microstructure of the Ni-B coating was characterized by SEM. The chemical composition of the Ni-B coating was analyzed by XRD and EDS, and the corrosion resistance of the coating was characterized by EIS and potentiodynamic polarization techniques. The results showed that the best morphology and the best corrosion resistance of the coatings were achieved when the plating solution temperature was 69.31 °C, the plating solution pH was 6.06, and the concentration of thiourea was 0.0015 g/L. The predicted impedance value was 5828.77 Ω, while the impedance value of the prepared coating based on the experimental setup parameters was 6041 Ω.