Inhibition of AZ31 Mg alloy corrosion by anionic surfactants

Gravimetric and electrochemical measurements were applied to study the inhibiting action exerted by some anionic surfactants (sodium salt of N-lauroylsarcosine, N-lauroyl-N-methyltaurine, dodecylbenzen-sulphonic acid or sodium lauryl sulphate) towards A231 Mg alloy corrosion in electrolyte solutions. The influence of the additive concentration, immersion time and type of surfactant was evaluated. Their inhibiting effects was attributed to a rapid adsorption on the metallic surface, which limited the cathodic reaction, followed by a precipitation stage with Mg++ ions that made the inhibiting layer thicker and less defective, so that, over time, the anodic oxidation was almost blocked in a wide potential interval. (c) 2012 Elsevier Ltd. All rights reserved.