A review on the application of inorganic nanoparticles in chemical surface coatings on metallic substrates

Abstract

Chemical surface coatings not only provide a powerful barrier between metallic substrates and their surroundings but also impart desired surface performances to an underlying substrate. Chemical surface coatings not only provide a powerful barrier between metallic substrates and their surroundings but also impart desired surface performances to an underlying substrate. Recently, the increasing public concern with industrial finishing systems has driven many investigations on the functional modification, such as the use of special chemical additives in the treatment bath, pre- and post-processing, of chemical surface coatings. However, these methods are being phased out due to their possible high-cost or harmful effects. Controlled addition of inorganic nanoparticles, without poison and contamination, to the treatment bath has become a good alternative due to the on-demand properties, including enhanced corrosion resistance and mechanical and functional properties, triggered by nanoparticles. This study focuses on the applications of inorganic nanoparticles in various chemical surface coatings such as electroless plating, electroplating, silane, and chemical conversion coatings. The discussed inorganic nanoparticles include TiO₂, SiO₂, Al₂O₃, ZrO₂, SiC, ZnO, CeO₂, MoS₂, and diamond and graphite nanoparticles. This review is also concerned with the dispersion methods of inorganic nanoparticles as well as the formation mechanism of nanocomposite coatings.