Performance Optimization of Electroless Coating on AH36 Steel Using Surfactant, Nickel Source and Reducing Agent

Performance Optimization of Electroless Coating on AH36 Steel Using Surfactant, Nickel Source and Reducing Agent V. Pradeep Kumar R. Muraliraja L. Martin J. Rajasekar

Electroless Ni–P coatings play a crucial role in improving the corrosion resistance, wear performance, and service life of marine-grade AH36 steel. In this study, the electroless coating process was systematically optimized to maximize coating thickness by controlling key bath parameters. The primary aim was to evaluate the influence of surfactant type, nickel source concentration, and reducing agent concentration on coating thickness. A Taguchi L27 orthogonal array was employed to design experiments, and coating thickness was selected as the response using a larger-is-better criterion. The results reveal that surfactant type has the most significant effect, followed by nickel source and reducing agent concentrations. Among the tested surfactants, the zwitterionic surfactant exhibited superior performance, producing a uniform coating thickness of approximately 25 µm, representing a notable improvement compared to conventional conditions. SEM cross-sectional analysis confirmed uniform and defect-free deposition, while EDS verified the formation of a medium-phosphorus Ni–P alloy. The optimized process demonstrates strong potential for reliable protective coatings in marine and structural applications. The optimized process parameters are zwitterionic surfactant at CMC level of 0.018 g/L, nickel source of 35 g/L, reducing agent of 30 g/L. The significance of this study lies in achieving a higher and more uniform electroless Ni–P coating thickness of about 25 µm (25% increase) on AH36 steel. This improvement is mainly due to the optimized use of a zwitterionic surfactant at its critical micelle concentration, along with higher nickel and reducing agent levels.
3 2026 3 2026 107 116 10.24874/ti.2072.11.25.01 https://www.tribology.rs/journals/2026/2026-1/2026-1-08.html