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Electrochemical studies of coatings and thin films

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2006, Doctor of Philosophy, Ohio State University, Materials Science and Engineering.
This dissertation reports findings on three different but related topics. Determination of cathodic kinetics for Al-containing phases is essential to characterize the corrosion behavior of high strength Al alloys. However, the current density measured from a potentiostat can be different than the true cathodic current because anodic dissolution occurs during cathodic polarization of Al alloys and a potentiostat only senses the net current. Therefore, it is necessary to use a nonelectrochemical measurement, such as Eletrochemical Quartz Crystal Microbalance (EQCM) technique. EQCM was used on thin film compositional analogs of S phase (Al2CuMg) particle, which is an important intermetallic particle commonly found in Al alloys, to evaluate the true cathodic current density. In principle, it should be possible to apply the EQCM technique to determine kinetic parameters, e.g., diffusivity of water. However, little research has been performed to relate this information to delamination and subsequent corrosion of the substrate under the coatings. Therefore, it is interesting to use EQCM for investigating water uptake in organic coatings, delamination, and corrosion on coated Al electrode. Electrochemical Impedance Spectroscopy (EIS) cannot accurately sense the initial degradation of protective coatings as they are just starting to fail because the low frequency impedance is typically higher than the input impedance of the EIS system for reasonably-sized samples. Changes in corrosion resistance of these good coatings cannot be sensed until a significant degradation occurs. Therefore, it is interesting to investigate other evaluation techniques to assess the early stage of organic coating failure. Potentiostatic Pulse Testing (PPT), which involves the application of potential steps instead of sine waves, holds promise for the evaluation of these protective coatings.
Gerald Frankel (Advisor)
198 p.

Recommended Citations

Citations

  • Kang, J. (2006). Electrochemical studies of coatings and thin films [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1138388240

    APA Style (7th edition)

  • Kang, Jiho. Electrochemical studies of coatings and thin films. 2006. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1138388240.

    MLA Style (8th edition)

  • Kang, Jiho. "Electrochemical studies of coatings and thin films." Doctoral dissertation, Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=osu1138388240

    Chicago Manual of Style (17th edition)