Influence of surfactants on electrodeposition of a Ni-nanoparticulate SiC composite coating

Nickel coatings containing well-dispersed, submicron (150-500 nm) silicon carbide particles were electrodeposited on copper from an agitated, modified Watts nickel electrolyte at 60 degrees C using current densities of 10-100 mA cm(-2). Coumarin additions (0-5 g dm(-3)) to a bath containing 10 g dm(-3) SiC at 6 A dm(-2) resulted in lower microhardness but considerably reduced abrasive wear in the composite coatings. Over 20 other surfactants including anionic, cationic, and non-ionic types were evaluated for their influence on the surface and tribological properties of the nanocomposite coatings. The surfactant levels (typically 0-3 g dm(-3)) were chosen to give good particle dispersions in the bath while avoiding any obvious deposit quality problems. Coating microhardness (via nanoindentation measurement), surface coefficient of friction (COF) and abrasive wear performance of the coatings under three-body, water-based conditions were investigated. The surfactants affected the degree of silicon carbide nanosized particles incorporated into the coating, from 5 to 54 vol.-%, and altered the surface microstructure from a matte to a bright surface finish and from porous to nodular, compact coatings. The nickel-nanosized silicon carbide composite coatings showed improved resistance to abrasive wear compared to a plain nickel (PN) deposit by a factor of 2-20.