The corrosion of aluminium in halogenated hydrocarbon solvents

Abstract

The behaviour of aluminium in 1,1,1-trichloroethane has been examined to determine conditions for the initiation of so-called bleeding corrosion and reasons for continued activity. Aided by the use of supporting electrolyte to enhance solution conductivity, it is evident that little reaction between aluminium and the solvent proceeds unless the air-formed film is mechanically damaged. However, mechanical damage per se is insufficient to allow continued reaction; thus, sufficiently high anodic potentials are also required in polarization studies. In natural immersion studies, the onset of bleeding corrosion is associated with a marked anodic excursion in potential, with dramatic net cathodic currents developed for specimens that were originally anodically polarized. Mechanisms for such behaviour suggest the requirement to sustain sufficiently large regions of bare metal, where solvent reduction outstrips repassivation in the inevitable presence of water in the solvent.