Influence of an ultrasonic field on lead electrodeposition on copper using a fluoroboric bath

The influence of three different types of stirring: mechanical, ultrasonic and a combination of both, on the mass transport coefficient and on the characteristics of the deposit of lead on copper electrodes has been studied. The results obtained show that ultrasounds always provide higher mass transport rates than mechanical stirring. The best deposition characteristics are obtained at 35 degrees C using a combination of ultrasound and mechanical stirring. Normally, ultrasounds increase the quality of the deposit by decreasing the number and size of dendrites. However, the sonication time has a strong influence on the adherence of the deposits. Thus, for long sonication times, part of the lead deposit detaches itself from the surface, giving deposits of very poor quality. A preliminary study of lead deposition on three-dimensional copper foam electrodes was made and similar results were obtained. With mechanical stirring, the interior of the foam was not coated with lead while when combined stirring was used, better results were obtained. However, for long sonication times the mechanical stability of copper foams is strongly decreased and the electrode is destroyed.