Effect of Saccharin and Sodium Dodecyl Sulfate Additives on the Structural and Morphological Properties of Ni-Fe Coatings

This study systematically investigates the synergistic effects of saccharin and sodium dodecyl sulfate (SDS) additives on the structural and morphological properties of electrodeposited Ni-Fe coatings. Copper substrates were electroplated in a sulfate-chloride electrolyte under controlled conditions (pH 5.5, 1 A/dm2, 10 min), with saccharin (0–0.5 g/L) and SDS (0–0.9 g/L) concentrations varied to optimize coating performance. Comprehensive characterization via SEM, XRD, and crystallite size analysis revealed that saccharin significantly refines grain structure, achieving minimal crystallite size (25 nm) and optimal surface homogeneity at 0.33 g/L. Conversely, SDS (0.4–0.6 g/L) reduced grain size to 18 nm but induced porosity and roughness at higher concentrations (0.9 g/L) due to hydrogen evolution. XRD analysis further demonstrated that SDS modulates phase homogeneity, suppressing secondary Ni-Fe alloy formation at elevated concentrations. The combined additives promoted (111)-oriented face-centered cubic (FCC) growth, enhancing microstructural integrity. Optimal parameters 0.33 g/L saccharin and 0.4–0.6 g/L SDS yielded coatings with refined grains, reduced internal stresses, and improved corrosion resistance. These results provide critical insights for tailoring high-performance Ni-Fe coatings in magnetic and anti-corrosion applications.