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Atmospheric Corrosion of Silver Investigated by X-ray Photoelectron Spectroscopy

Lemon, Christine Elizabeth
http://rave.ohiolink.edu/etdc/view?acc_num=osu1350660429

Abstract Details

2012, Doctor of Philosophy, Ohio State University, Chemistry.
Atmospheric corrosion is a costly problem. Accelerated laboratory tests, such as the salt fog chamber, have been created to predict corrosion of materials without the need to expose them over long periods of time outdoors. However, these accelerated tests often do not accurately reproduce the types and rates of corrosion found in field exposures. Silver exhibits this discrepancy and has been used in recent years in an attempt to correct the shortcomings of these accelerated tests. This study identifies Ag2SO3 and Ag2SO4 on field-exposed silver coupons. The presence of these species on field-exposed silver has been contested in the literature. Evidence suggests that Ag2SO3 is an intermediate step in the formation of Ag2SO4. Furthermore, the presence of alkali cations, such as Na+, determines the final oxidation state of the sulfur species on silver. If Na+ is present, Ag2SO4 is the final state, whereas Ag2SO3 is not found in the presence of alkali cations. The identification of sulfite and/or sulfate on field-exposed samples suggests the need for further improvement of salt fog tests which do not currently include a sulfur source. In addition to proposing a mechanism for sulfate formation, this study also proposes a link between AgCl formation on inland samples and continental chloride sources. AgCl has been previously reported to form on silver exposed at nearly every location regardless of the proximity to marine sources. Studies have shown that ClNO2, which is a reservoir species for chlorine, releases Cl radical when photolyzed. High levels of ClNO2 have been reported at locations which are not near salt water sources. This study provides further evidence that AgCl is formed in every exposure location, with only one exception. The lack of correlation of cations, such as Na+, which are present in sea spray aerosols to Cl- on silver samples, is consistent with a non-salt water source of inland chloride. The abundance of ClNO2 and therefore Cl radical at non-marine areas may be the cause of inland AgCl formation.
Heather Allen, PhD (Advisor)
Gerald Frankel, PhD (Committee Member)
Prabir Dutta, PhD (Committee Member)
Barbara Wyslouzil, PhD (Committee Member)
Samuel Stout, PhD (Committee Member)
250 p.
Chemistry; Materials Science
corrosion; silver; XPS; Ag2SO4; atmospheric corrosion

Recommended Citations

Citations

  • Lemon, C. E. (2012). Atmospheric Corrosion of Silver Investigated by X-ray Photoelectron Spectroscopy [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1350660429

    APA Style (7th edition)

  • Lemon, Christine. Atmospheric Corrosion of Silver Investigated by X-ray Photoelectron Spectroscopy. 2012. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1350660429.

    MLA Style (8th edition)

  • Lemon, Christine. "Atmospheric Corrosion of Silver Investigated by X-ray Photoelectron Spectroscopy." Doctoral dissertation, Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1350660429

    Chicago Manual of Style (17th edition)

osu1350660429
985
© 2012, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.