Aluminium behaviour and stability in AlCl3/DMSO(2) electrolyte

Cathodic and anodic behaviour of aluminium has been investigated in AlCl3/DMSO(2)-dimethylsulfone-(1 mole/kg) electrolyte at 130 degrees C by current reversal chronopotentiometry (CRC) and chronoamperometry. Al deposition study showed that a diffusion-limited current density close to 83 mA cm(-2) is reached for potentials less than -0.5 V vs Al-III/Al while Al dissolution is carried out under ohmic control. The corrosion of aluminium during its storage in the electrolyte has also been studied. Electrochemical and spectroscopic investigations showed that Al and the electrolyte react with each other; the reaction leads to the formation of a passivating layer by accumulation of the resulting corrosion products at the metal surface. Al corrosion involves a diffusion process of the electrolyte through the passivating layer and a dissolution phenomenon of this passivating layer, that occur simultaneously. The diffusion-limited process prevails in the beginning of the storage and then Al corrosion mainly depends on the degradation rate of the passivating layer. Moreover, degradation products from DMSO(2) were detected in the passivating layer. Copyright (C) 1996 Elsevier Science Ltd.