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Corrosion Damage Evolution of a Unidirectional Pit

McKinnon, John Motley
http://rave.ohiolink.edu/etdc/view?acc_num=akron1463754286

Abstract Details

2016, Master of Science, University of Akron, Applied Mathematics.
A three-stage, unidirectional pit growth model, from initiation to stable growth and repassivation as the bulk potential is decreased, is developed. Stage I models metastable pit growth under ohmic control and a constant current density. Here it is assumed that the pit is covered by a semi-permeable oxide layer. Stage I is terminated when the metal concentration reaches its saturation limit at which time the pit cover instantaneously bursts. Stage II models the stable pit growth under diffusion control and the formation of a salt film at the bottom of the pit. During Stage II the bulk potential is decreased at a specified scan rate. When the bottom pit potential reaches the transition potential, Stage III begins. Here we model the pit growth under ohmic control, for a prescribed polarization curve, until the metal repassivates as the potential is decreased. The governing system of equations for each stage is solved numerically to determine the potential drop, and the concentrations of sodium, chloride, and metal ions within the pit. The pit depth as a function of time is determined from Faraday's Law in Stages I and III, and from a mass balance at the electrolyte/metal interface in Stage II. The cumulative pit depth is fit to a power law model that is used in existing Markov models for pit initiation and growth, and is compared with experimental pit depths for stainless steel in seawater.
Curtis Clemons, Dr. (Advisor)
Kevin Kreider, Dr. (Committee Member)
Gerald Young, Dr. (Committee Member)
Timothy Norfolk, Dr. (Committee Chair)
85 p.
Mathematics
pitting corrosion; unidirectional pit growth; corrosion damage evolution; ohmic controlled; diffusion controlled; metastable growth; stable growth; repassivation; stainless steel in seawater

Recommended Citations

Citations

  • McKinnon, J. M. (2016). Corrosion Damage Evolution of a Unidirectional Pit [Master's thesis, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1463754286

    APA Style (7th edition)

  • McKinnon, John. Corrosion Damage Evolution of a Unidirectional Pit. 2016. University of Akron, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1463754286.

    MLA Style (8th edition)

  • McKinnon, John. "Corrosion Damage Evolution of a Unidirectional Pit." Master's thesis, University of Akron, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1463754286

    Chicago Manual of Style (17th edition)

akron1463754286
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© 2016, all rights reserved.
This open access ETD is published by University of Akron and OhioLINK.