Skip to Main Content
 

Global Search Box

 
 
 
 

Files

File List


Masters Thesis_DTKaminski_Final.pdf (6.21 MB)

ETD Abstract Container

Abstract Header

Corrosion Inhibition of Magnesium Alloys and Influence of Atmospheric Carbon Dioxide

Kaminski, Daniel Thomas
http://rave.ohiolink.edu/etdc/view?acc_num=osu1460241073

Abstract Details

2016, Master of Science, Ohio State University, Materials Science and Engineering.
The widespread use of magnesium alloys as an engineering material is yet to be realized due, in part, to poor corrosion resistance in condensing moisture environments. Application of corrosion inhibitor compounds by way of coatings-based inhibitor systems is one corrosion mitigation method that can be implemented to address this concern. This work comprises a fundamental study of corrosion inhibitors for magnesium alloys AZ31 and WE43. A broad array of corrosion inhibitors were examined at 1-100 mM concentration including transition metal oxyanions, group IVA through group VIIA anions, as well as rare earth cations, and selected organic compounds. Due to potent and rapid surface alkalization of magnesium alloys and the potential application of inhibitors as functional pigment additives in organic coatings, it is of concern whether atmospheric carbon dioxide absorbed within alkaline electrolytes could interact with corrosion inhibitors in a favorable, negative, or neutral way. Reactive-transport modeling of carbon dioxide gas absorption in such electrolytes was conducted with respect to experimental conditions. From this, it was understood that equilibrium concentration of dissolved inorganic carbon at experimentally observed pH values can be realized in thin electrolyte layers upon time duration of several hours to days. Slow absorption of carbon dioxide gas into alkaline aqueous solution of experimentally observed pH is primarily due to the rate limiting kinetics of carbon dioxide hydroxylation at a given gas-liquid interface surface area and electrolyte volume. To help develop an understanding of the interaction of corrosion inhibitors for AZ31 and WE43 with ambient carbon dioxide, a novel closed-system test cell technique was developed to decouple CO2 from the system. It was observed that ambient levels of CO2 play an important role in the corrosion of AZ31 and WE43 alloys and furthermore influences corrosion inhibitor effectiveness. In the absence of corrosion inhibitors, experimental results showed that ambient carbon dioxide acts to buffer the pH of the electrolyte in contact with either AZ31 or WE43 during corrosion towards a lower pH than would develop if carbon dioxide was absent. For AZ31, results showed that dissolved carbon dioxide affects the corrosion morphology and surface films favorably and can lead to an approximately five times decrease in corrosion rate. For WE43, dissolved ambient levels of CO2 slightly accelerated the corrosion rate and increased general surface corrosion compared to a CO2-free environment. In the presence of corrosion inhibitors, the critical concentration for inhibition by the tested compounds was much better resolved by use of the novel closed-system test cells compared to conventional methods. This proved to be an unanticipated advantage of the novel test cell’s use. Side-by-side comparison of known, effective, corrosion inhibitors in the presence and absence of ambient levels of CO2 indicated mostly neutral or negative interaction of test inhibitors with dissolved CO2, although exceptions were documented. Additionally, film formation and corrosion inhibition was noted for 10mM and 100mM sodium metavanadate on both alloys and all conditions tested. Significant corrosion inhibition was noted on AZ31 by sodium tungstate, particularly, in the absence of ambient carbon dioxide. The information generated by this work can be utilized in the future development of effective coatings-based corrosion inhibitors for magnesium alloys.
Rudolph Buchheit (Advisor)
Gerald Frankel (Committee Member)
214 p.
Chemistry; Materials Science

Recommended Citations

Citations

  • Kaminski, D. T. (2016). Corrosion Inhibition of Magnesium Alloys and Influence of Atmospheric Carbon Dioxide [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1460241073

    APA Style (7th edition)

  • Kaminski, Daniel. Corrosion Inhibition of Magnesium Alloys and Influence of Atmospheric Carbon Dioxide. 2016. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1460241073.

    MLA Style (8th edition)

  • Kaminski, Daniel. "Corrosion Inhibition of Magnesium Alloys and Influence of Atmospheric Carbon Dioxide." Master's thesis, Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1460241073

    Chicago Manual of Style (17th edition)

osu1460241073
2,279
© 2016, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.