Morphology evolution of Au/B4C electrodeposited composites

Electrodeposition of Au/B4C composites is attractive for the achievement of hard and termally stable Au films displaying outstanding tribological perf ormance. The addition of micrometric B4C particles to Au electrodeposition baths brings about time-dependent morphological variations on the micromete r scale, eventually reaching a steady state behaviour. These morphological variations are a function of growth rate, amount of particles suspended in the bath and hydrodynamic conditions. A systematic experimental investigati on of these effects was carried out by in-plane and cross-sectional SEM obs ervations. An image-analysis procedure for the evaluation of the effective surface area was set up. Correlations bewteen operating conditions and volu me fraction of ceramic in the composite are proposed, based on image analys is of SEM micrographs. Morphology evolution data can be used to model indep endently measured electrochemical quantities related to the effective catho de surface area.