ELECTROCHEMICAL STUDY OF THE PITTING CORROSION OF ALUMINUM AND ITS ALLOYS .3. THE ROLE OF BONDED WATER AND THE KINETICS OF FORMATION AND REFORMATION OF A PASSIVE LAYER

Hydrogen evolution and aluminium electrodissolution processes were inv estigated by cv and coulometric methods on Al electrode at the cathodi c end of the polarization curve. The proton or water is reduced at the passive layer with a diffusion controlled rate. The water content of the passive layer on Al was investigated by a radiotracer technique us ing tritium labelled water. The water content of passive layers formed by different processes is different. By short-term sorption experimen ts an oxide layer reformation process was detected; a new (EPDP) model was proposed for the formation of the passive layer on aluminium and indicated by the variation of the pitting potential and the aluminium content of solution.