Electroless Ni–P–SnO₂ and Ni–P–Mn₂O₃ Composite Coatings on AH36 Marine Steel
J. Environ. Nanotechnol., Volume 15, No 2 (June 2026) pp. 125-134
Abstract
Electroless coating offers a promising method for enhancing the properties of structural materials such as AH36 steel by applying protective surface layers that improve corrosion resistance and mechanical durability. This study investigates the development and evaluation of electroless nickel–phosphorus–tin(IV) oxide (Ni–P–SnO₂) and nickel–phosphorus–manganese(III) oxide (Ni–P–Mn₂O₃) composite coatings incorporating manganese oxide and tin oxide nanoparticles synthesized via a precipitation method. Optical microscopy and SEM analyses revealed a uniform and pore-free coating distribution across the substrate. EDS identified the elemental composition of the deposits, confirming the presence and uniform dispersion of nickel, Mn₂O₃, and SnO₂ nanoparticles. Mn₂O₃ reinforcement significantly improved microhardness (up to 545 HV). Microhardness tests indicated a substantial increase in hardness of 14.6% for the coated AH36 steel compared to the untreated material, highlighting its enhanced mechanical performance. AFM imaging demonstrated smoother surface topography and reduced roughness (126% improvement) in the coated samples, suggesting improved surface quality and potential for lower friction in practical applications. Scratch resistance tests further validated the durability of the coated surface, making it suitable for demanding environments. The corrosion resistance of the Ni–P-coated substrate improved significantly by 16.4% compared to the uncoated substrate.
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