How to get started with pulse plating

摘要

Pulse plating is the electrolytic deposition of metals by a periodic variation of current or voltage. A broader definition includes the related areas of pulse anodizing and pulse polishing. Pulse plating processes are divided into ordinary pulsed current (PC) plating, or uniform waveforms, and periodic current reversal (PR) plating, or bipolar waveforms. The electrodeposition can be either galvanostatic or potentiostatic. In the former, the reaction rate is maintained constant by letting the current be the controlling factor. In potentiostatic control, the potential is constant, which causes the current to change with time. The advantage of using pulse plating versus conventional, direct current (DC) plating is the strongly increased number of independent parameters controlling the deposition process. In pulse plating, one and the same average current density is represented by an unlimited number of waveforms constructed by a number of independent combinations of cathodic/anodic current densities and the duration of pulses/pauses. In DC plating, the current density represents only one independent parameter. It has been shown that it is not only possible to improve the quality of existing plating processes, it is even possible to deposit coatings and alloys, which cannot be deposited under DC conditions. The strength of the pulse plating technology is the high degree of freedom to choose almost unlimited deposition conditions. However the strength seems to be a weakness as well. The high degree of complexity decreases the chance of successful utilization of the technology. Statistical designs of experiments are necessary and it is important to realize that process conditions known from DC plating might not necessary be the best conditions when plating is made with pulsed current. The following contains some basic information, which should be taken into consideration when exploring the potentials/advantages for surface treatment with pulsed current.