Electrodeposition of graphite-bronze composite coatings and study of electroplating characteristics

The aim of this research is to obtain composite coatings of bronze (90% Cu-10% Sn) with graphite particles. The electrodeposition of G-Cu (Sn) composites from an alkaline bath containing cyanide is described. Composite coatings consisting of graphite particles and copper-tin were prepared by means of the conventional electrocodeposition (CECD) and sediment codeposition (SCD) techniques. The graphite particles involved were less than 10 mum. The dependence of graphite amount in the composite coatings was investigated in relation to the graphite concentration in bath, cathode current density, stir rate and technique type and it was shown that these parameters strongly affected the volume percentage of graphite. The deposition efficiency with and without graphite particles in bath was studied. The morphology and phases of the electrodeposited composite were studied. Composite coatings were obtained with roughness significantly higher than the bronze alloy coatings. The graphite distribution in composite coatings at low concentrations of graphite in bath was uniform across the coating, but at high concentrations, graphite particles on the surface were agglomerated. The graphite percentage in composite coatings obtained was up to 8.5% (vol.) in the CECD and 11.8% (vol.) form the SCD technique. (C) 2004 Elsevier B.V. All rights reserved.