Preparation and characterisation of nickel–nano-B 4 C composite coatings

Ni–B₄C composite coatings on carbon steel surfaces with various contents of nano-B₄C particulates were prepared by electrodeposition in Ni plating bath containing nano-B₄C particulates. Microhardness, scanning electron microscopy (SEM), Tafel and electrochemical impedance spectroscopy (EIS) measurements were used to compare pure nickel coating and Ni–B₄C composite coatings. The microhardness of Ni–B₄C coatings is higher than that of pure Ni coating, together with the microhardness of the composite coatings increases with the increase of the content of nano-B₄C particulates. The effects of various contents of nano-B₄C particulates on the corrosion resistance were investigated and it was found that the best anticorrosion property of Ni–B₄C composite coatings is at 6 g L⁻¹ B₄C in the bath formulation.