Electrodeposition of bronze-PTFE composite coatings and study on their tribological characteristics

The aim of this paper is to obtain lubricant composite coatings of bronze (copper with 10-15% tin) with PTFE (polytetrafluoroethylene) particles over mild steel substrate and to evaluate their tribological properties. The electrodeposition was carried out from an alkaline bath containing cyanide. The composite coatings were prepared by means of CECD (Conventional Electrodeposition) and SCD (Sediment Co-deposition) techniques. PTFE suspension with an average particle size of 0.3 mu m was used. The incorporation of PTFE in the composite coatings was investigated with respect to the PTFE concentration in bath, cathode current density, and mode of deposition. The cathode efficiency of the coating was calculated. The PTFE distribution in the composite coatings, as examined with SEM, are uniform at low concentration of PTFE in the bath and agglomerated at high concentrations. The PTFE incorporation in the SCD technique is higher than that of the CECD technique. Physical properties of the composites including hardness, wear resistance and roughness etc., were measured. (c) 2006 Elsevier B.V. All rights reserved.