KINETICS OF FORMATION OF PASSIVE LAYER ON ALUMINUM

Formation of passive layer on aluminium was investigated in aqueous media by tritium radiotracer, ICP and electrochemical methods. The triticum and aluminium contrations in the solutions as well as the critical pitting potential (E(pi)) of aluminium species change similarly in alternative direction during passivation. The passive layer formation can be described by the ''electrochemical dissolution - precipitation - dissolution - precipitation'' (E.P.D.P.) model. The new model is in accordance with the obtained experimental results and allows to clarify the debated phenomena published in the literature.