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Title:The anodic oxidation of metals
Author(s):DeSmet, Donald John
Doctoral Committee Chair(s):Bartlett, J.H.
Department / Program:Physics
Subject(s):anodic oxiation
passive iron electrodes
overpotential parameters
neutral electrolyte
Abstract:OptiGa~ mefislH;oementl;i 01; anoMc oxide su:r~ace layers on passive i;ronelectJ;'Qc;les hav~ been made anQ are cqmpared with electrica1 mealill,ll:eJ;llent;s qf 'One q~paci\:anQ~ and other overpqteQ.tia1 parameters ~ Re.su1ts of t:hes~ st1,ldies snow that the surface layer on the electrQde may be t"egarqed as ~onsistil1g of more than one part. Specifically in a neutral e~ect:rQlyce there is a thin conducting layer oJ constant thic~ness present on the electrode surface in addition to the electrically limiting layer of variable thickness~ while in acid electrqlyte there is a layer located outside the electrical1y limibing layer which grows at a constant rate to large thicknesS when the ehctr()de h held, in the "steady state" in the ~assive region. This thick layer can be removed by holding the electrode at a potential sl~ghtly below the passive region. Changes in the thickness of the electrically limiting layer, determined opti~ cally are consisten~ with a field dependent conduction mechanism. Optical and electical measurements during the anodic oxidation of nickel have also been made: The results of these measurements indicate that the behavior of passive nickel is more complicated than that of passive iron. Electrical results show that the form of the equation relating the current to the potential is of the same form as it is for passive iron, however for nickel the behavior of the parameters in this equation is found to differ significantly from that of iron at higher passivaring potentials. Optical measurements indicate that a layer or layers form on the nickel electrode surface when it is made passive, however the optical parameters do not behave in as simple a manner as they do for iron and it is impossible to analyze the data uniquely. The anodic oxidation of tantilum was studied by analyzing open· circuit transients applied at intervals along galvanostatic oxidation transients, The dependence of the c4rrent density, i, on the overpotential, V, is expressed in an equation of the form i = io exp(V/vo), and values are given for io and Vo' Under galvanostatic conditions the parameter Vo varies linearly with the potential of the electrode, while 10 is found to depend on the oxidation current density. These results show strong similarities to results obtained by others for the anodic oxidation of iron in a neutral electrolyte.
Issue Date:1967
Genre:Dissertation / Thesis
Rights Information:1967 Donald John DeSmet
Date Available in IDEALS:2011-07-07
Identifier in Online Catalog:6094670

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