Square wave pulsating overpotential treatment of chromic acid solution

Abstract

Systematic investigation of square wave pulsating overpotential (SWPO) treatment of a chromic acid solution is presented. Some preliminary potentio dynamic scans, potentiostatic depos its, potential steps and capacitance vs. potential curves were measured in order to establish the practical range of the SWPO signal parameters. The results show that properly adjusting the lectrochemical param eters of the cyclic alternating potential perturbation it is possible to obtain cracked or crack free metallic chromium or cromium oxide/hydroxide mixed coatings. The different deposit morpholo gies were characterized through scanning electron microscopy and their chemical composition and micro hardness was measured. Some insight into the possible mechanisms of coating growth under this potential cycling treatment is given.