ELECTROCHEMISTRY AND METHODS FOR THE ELECTROPOLISHING OF REFRACTORY METALS IN LOW-TEMPERATURE CARBAMIDE-CONTAINING MELTS

摘要

The mechanism of electrodissolution of niobium, tantalum and titanium in carbamide-NH_4Cl and NH_4F melts as well as the structure of the complex ion formed in the melt have been studied by electrochemical and spectroscopic methods. In carbamide-containing melts all metals are passivated, and the depassivation of metal surface is possible under the action of some agents. Methods of Nb, Ta, Ti electropolishing were also developed. For all metals studied, the results obtained for the main parameters, surface finish class and brightness, fall within the required polished surface parameters.