Preparation and characterization of nickel-cobalt-diamond electro-composites by sediment co-deposition

Nickel-diamond and nickel-cobalt diamond coatings were produced by electrodeposition using sedimentation technique on mild steel substrate and their tribological properties evaluated. Electrodeposition was carried out from a conventional Watts bath with cobalt addition. The conditions to obtain nickel-cobalt alloy were optimized first and then the conditions for obtaining diamond composites from both systems were investigated. Natural diamond powder of 6-12 mu m size was used in the study. The volume percent incorporation of diamond powder in the coatings was investigated with respect to its concentration and cobalt concentration in bath, cathode current density, pH and temperature. The diamond powder distribution in the composite coatings, as examined with SEM, are uniform at low powder concentration in the bath and agglomerated at high concentrations. Physical properties of the composites including hardness, wear resistance and roughness were measured. Presence of cobalt increased volume percent incorporation of diamond powder, hardness and wear resistance of the coatings. (c) 2006 Elsevier B.V. All rights reserved.