Effects of different surfactants on the silica content and characterization of Ni-SiO2 nanocomposites

This article presents a method for the electrochemical preparation of a coating of nickel-silica nanocomposites on a carbon steel substrate. The incorporation of hydrophilic silica particles into the Ni composite coating during co-electrodeposition is so difficult due to the small size and the hydrophilicity of SiO2 particle, generally less than 2 v% of silica is incorporated into the composite at different current densities, agitation speeds and silica concentrations. The effect of the presence of four surfactants, namely cocamidopropyl betaine (CAPB), decylglycoside (DG), cetyltrimethyl ammonium chloride (CTAC) and ammonium lauryl ether sulfate (ALES), on overcoming this problem was investigated in this research, and the surfactants were found to greatly influence the surface charge of silica, silica incorporation percentage and the microstructure of the composite. In fact, upon increasing the internal stresses, the products prepared in the presence of CAPB and DG were found to crack to some degree. CTAC was found to lead to entrapment mode silica co-deposition in the Ni coating. Furthermore, the addition of ALES into an electrolyte bath negatively supercharged silica surfaces and increased silica dispersion, which led to a dramatic increase in the silica incorporation percentages to around 14 v%. The results showed that Ni-SiO2 composites prepared in the presence of ALES had better corrosion resistance, hardness and wear properties. [GRAPHICS] .