Study on the Effects of Additives on the Performance of Ni-Co-P Alloy Coatings Using Box-Behnken Design

To understand the effects of additives on the performance of a Ni-Co-P alloy electroplated coating, this study, based on a single-factor experiment, utilized a Box-Behnken experimental design to optimize an additive that can enhance the electrodeposited Ni-Co-P alloy coating's properties, including hardness, glossiness, and corrosion resistance. The study used tools such as a gloss meter, a Vickers hardness tester, and an electrochemical workstation to analyze the impact of different additives on the coating's hardness and gloss. The optimal additive combination was determined. The results from the Box-Behnken experiment showed that when the concentrations of sodium dodecyl sulfate, thiourea, and sodium allyl sulfonate reached 0.10, 0.15, and 0.22 g/L, respectively, the resulting coating hardness was 475.4 HV_0.5, and the gloss level was 463.4 GU. Compared to the coatings without additives, the hardness increased by 90.34 HV_0.5, and the glossiness rose by 101.2 GU. The coating's corrosion resistance also improved. This enhancement is attributed to the compounded additive, which significantly improved the surface morphology of the coating, making it smoother and more compact. The morphology and composition of the coatings with additives were analyzed through scanning electron microscopy and energy dispersive X-ray spectroscopy, and the composition of the coating contains 71.01 at % Ni, 20.65 at % Co, and 8.34 at % P. At the same time, the optimized coating exhibits a metallic luster similar to stainless steel, meeting industrial requirements.