PERTURBATION OF THE FLOW OF CURRENT TO A DISK ELECTRODE BY AN INSULATING SPHERE

A quantitative basis for the interpretation of the electrochemical noi se generated either by particles approaching an electrode during compo site plating or by bubble formation at a gas evolving electrode is pre sented. Heretofore, the increase of the electrolyte resistance of the flow of current to a disk electrode caused by an insulating sphere was determined experimentally and theoretically. The experimental study w as carried out by displacing a glass or corundum ball glued to a glass fiber by means of a translation stage in front of a small disk electr ode embedded in an insulator. The high frequency limit of the ac Imped ance was used to avoid electrode polarization effects. In parallel, th e incremental resistance due to the sphere was calculated theoreticall y by using a recently developed model based on a boundary collocation method which was specially developed for this purpose. Theoretical and experimental values were found to be in excellent agreement, the devi ations being due to the limited experimental accuracy of the resistanc e measurements.