Protective effects of some anionic surfactants on an Ag-containing aluminium alloy (AA2139). Comparison with the action on a Li-containing aluminium alloy (AA2198)

The influence exerted by some anionic surfactants towards the corrosion process of an Ag-containing aluminium alloy (AA2139) is studied during 168 h immersion in 0.01 M NaCl solution. This behaviour is compared with that previously determined on a Li-containing alloy (AA2198). The surfactants, at a proper concentration, hinder anodic and cathodic reactions as well as the pitting process, but their action is influenced by passive layer stability, so that their inhibiting effects are greater on AA2198 for the more efficient and stable passive layer. On both alloys, the most efficient compounds are the sodium salts of N-lauroylsarcosine and of dodecylbenzensulphonic acid.