Effects of bivalent Co ion on the co-deposition of nickel and nano-diamond particles

Nano-diamond particles were co-deposited on AISI-1045 steel substrates with nickel from a Watts-type bath by conventional electrodeposition methods. The effects of Co2+ additives on the co-deposition of nano-diamond particles, the surface morphology, microhardness, surface roughness and tribological properties of nanocomposite coatings were investigated. Results in this paper showed that the addition of Co2+ in the Ni/diamond plating bath significantly improved the amount and uniformity of dispersed nano-diamond particles in the metal matrix. Moreover, it has been established that the nanocomposites obtained with the addition of Co2+ in the Ni/diamond plating bath produced much higher hardness and excellent anti-wear performance with lower friction coefficient when sliding against a steel ball. It has been assumed that Co2+ may act as a cationic stimulator, which promoted the co-deposition of nano-diamond particles with nickel and thus intensified the positive contribution of the embedded nano-diamond particles.