Ethylenediamine as a Corrosion Inhibitor for Aluminium Alloys in Hydrochloric Acid

Ethylene diamine was evaluated as a short-term inhibitor for aluminium alloys, 2S, 57Sand 65S in hydrochloric acid. At 43·5 ml/l concentration, it afforded complete protection to all the alloys in 1·0 N hydrochloric acid for up to three hours in the temperature range 35–55°c. At higher concentrations of hydrochloric acid, its efficiency was 97–99·5%. Ethylenediamine reduced the externalcathodic protective current, gave cathodic protection and inhibition by lowering the potential requirements and by increasing the anodic and cathodic polarisation characteristics of the metal surface. At concentrations up to 17·4 ml/l, ethylenediamine accelerated corrosion of the 2S alloy.