On the Mechanism of Niobium Electropolishing

The mechanism of Nb electropolishing was studied. In particular, the effects of acid concentration, stirring, temperature and amount of material removed on the surface finish were investigated using electrochemical polarization measurement, galvanostatic and potentiostatic techniques. A current density plateau in the niobium polarization curves, characteristic of mass transport control, was observed. Fluoride ion was shown to be the transport-limited species. Galvanostatic results deviated from a perfect semi infinite linear diffusion model, indicating the effects of diffusion and temperature gradients. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.054211jes] All rights reserved.