Summary
Aqueous chemical deposition (ACD) of Ni-P and Co-P films can be controlled with a secondary current pulse (SCP) technique, measuring the voltage variation at an electrode on which electrodeposition is already occurring at constant current density as a consequence of short square current pulses, in the ms range. The transient voltage curves are interpreted and three parameters obtained: the transient Tafelslope, related to metal ion electrochemical discharge mechanism, the surface adsorption capacity and the surface ohmic resistance. The influence of H2 or 02 saturation in the bath on the deposition kinetics and on the structure of thin layers is shown, and the mechanism of bath stabilization by several additives is interpreted.