Cast iron is a widely used engineering material due to its mechanical strength and machinability, but its inherent limitations in wear and corrosion resistance restrict its use in demanding environments. To address this, a nickel–phosphorus (Ni–P) coating was deposited on cast iron substrates using an electroless dip coating technique, and its performance was compared with uncoated samples. Wear tests were carried out on both uncoated (UC) and Ni–P coated (NC) specimens under applied loads of 5, 10, and 15 N, with a sliding velocity of 0.5 m/s over a sliding distance of 500 m. The coated samples consistently showed lower wear loss compared to uncoated specimens, with the best performance observed for NC3 at 15 N, where the wear rate reduction was significant. Hardness measurements confirmed that the Ni–P coated surface exhibited higher hardness than the base cast iron, indicating effective strengthening due to the phosphorus-rich Ni–P layer. Corrosion studies demonstrated improved resistance of coated samples, as the Ni–P barrier reduced active surface degradation in corrosive medium compared to rapid attack on uncoated cast iron. Microstructural analysis revealed a uniform and dense coating on the cast iron substrate, contrasting with the porous and heterogeneous surface of the uncoated sample. The combined improvements in hardness, wear resistance, and corrosion performance confirm that electroless Ni–P coating significantly enhances the tribological and environmental durability of cast iron.

Keywords: Cast iron, Ni–P coating, electroless dip coating, wear resistance, corrosion resistance, hardness, microstructure