Process and properties of electroless Ni–Cu–P–ZrO2 nanocomposite coatings

Electroless Ni–Cu–P–ZrO2 composite coating was successfully obtained on low carbon steel matrix by electroless plating technique. Coatings with different compositions were obtained by varying copper as ternary metal and nano sized zirconium oxide particles so as to obtain elevated corrosion resistant Ni–P coating. Microstructure, crystal structure and composition of deposits were analyzed by SEM, EDX and XRD techniques. The corrosion behavior of the deposits was studied by anodic polarization, Tafel plots and electrochemical impedance spectroscopy (EIS) in 3.5% sodium chloride solution. The ZrO2 incorporated Ni–P coating showed higher corrosion resistance than plain Ni–P. The introduction of copper metal into Ni–P–ZrO2 enhanced the protection ability against corrosion. The influence of copper metal and nanoparticles on microhardness of coatings was evaluated.