Pulse and direct electrodeposition of Ni–Co/micro and nanosized SiO2 particles

Abstract

ABSTRACTNi–Co/SiO2 composite coating was electrodeposited on the steel substrate. The coatings were characterized by X-ray diffraction and scanning electron microscopy. The microhardness of the composite coatings was studied by variation of the electroplating parameters, such as the pulse current (PC) and direct current (DC) electrodeposition methods, deposition temperature, electrolyte pH, concentration of surfactants, sodium dodecyl sulfate (SDS), and cetyltrimethylammonium bromide (CTAB). Zeta potential of SiO2 particles measurements was performed with various pH, SDS, and CTAB concentrations. The data depict that the hardness of Ni–Co/SiO2 nanocomposite coatings manufactured by PC electrodeposition increases with the increase of bath temperature, pH, SDS, and CTAB concentration up to 50°C, 4.6, 0.3, and 0.2 g/L, respectively. Beyond mentioned optimum values, the microhardness of nanocomposite coating decreases. Using DC method led to reduce the microhardness. Utilizing SiO2 microparticles instead of SiO2 nanoparticles for reinforcing resulted in declining the microhardness. The friction coefficient and wear results demonstrated that using PC method and nanosized particles led to reduce the friction coefficient and increase the resistance to wear. Anodic polarization results illustrated that using SiO2 nanoparticles and PC method to prepare coating caused corrosion resistance of coating in a 3.5 wt% NaCl solution to enhance.