ANODIC-DISSOLUTION OF METALS - PROCESS-CO NTROL BY MASS-TRANSPORT

There are many parameters involved in the anodic dissolution of metals . Stationary methods are not enough for describing the dissolution kin etics in a way to better interpret the corrosion processes. The use of electrochemical and electrohydrodynamic impedances gives complementar y information. The analysis of the EHD impedance together with station ary results. has implied the elaboration of mechanisms, taking into ac count mass transport processes in the electrolyte or, at the interface neighbourhood. Two examples will illustrate this discussion: (i) Iron anodic dissolution in sulphuric acid. which involves a viscosity grad ient from the interface to the solution; (ii) Cooper anodic dissolutio n in chlorhydric acid, which involves a salt layer covering the interf ace.