The influence of some triphenylmethane compounds on the corrosion inhibition of aluminium

Potentiostatic and potentiodynamic polarization, and scanning electron microscopy were used to investigate the effect of some basic and acid triphenylmethane derivatives, on the anodizing of pure aluminium in neutral ammonium borate electrolyte containing traces of chloride ions. The absence of sulfonic groups as substituents in these compounds restricts their action. The presence and position of sulfonic groups as substituents in their molecules influence the extent to which the molecular structures of these compounds approach coplanarity and their electronic configuration. As a result, a differentiation of their influence on the field assisted adsorption of chloride ions from solution on the hydrated oxide surface, and on the subsequent localized autocatalytic dissolution of the barrier oxide film by them is observed. (C) 2003 Elsevier Ltd. All rights reserved.