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Spring 2009 Seminar Series
Wednesday, June 3, at 3:30 p.m.
Room 264 MacQuigg Labs
Dong Liang
PhD Candidate advised by Dr. Gerald Frankel
Department of Materials Science and Engineering
The Ohio State University
Role of Chloride, Ozone & UV on Atmospheric Corrosion of Silver
Abstract
Initial efforts focused on the effects UV radiation, O3, relative humidity on the atmospheric corrosion of bare silver. Later work addressed the corrosion of silver samples deposited with NaCl particles. An exposure chamber that can simulate various environmental effects was built. The effects of UV radiation, O3, and relative humidity were varied separately while keeping the other factors the same level. The corrosion products were analyzed by the galvanostatic reduction method and characterization techniques such as SEM and EDS. It was found that both UV and O3 are necessary for fast corrosion on bare silver and this fast corrosion reaction results from atomic oxygen generated photodegradation of O3. In the presence of UV and O3, relative humidity has little effect on the atmospheric corrosion of bare silver in contrast to conventional atmospheric corrosion. After investigations on atmospheric corrosion of bare silver, focus was put on the atmospheric corrosion of silver with NaCl particles deposited on the surface. Nanometer-sized NaCl particles were successfully deposited on bare silver surface by the thermophoretic deposition method. The deliquescence of NaCl particles was studied in-situ with environmental SEM (ESEM). Field exposed samples from across the U.S. were analyzed by SEM, EDS and then reduced in deaerated 0.1 M Na2SO4 solution at pH 10 to determine the type and amount of corrosion products. Samples with NaCl particles were exposed in a chamber with similar conditions as for bare silver. Various environmental effects such as UV radiation, O3, and relative humidity were investigated. O3 was found to cause corrosion of silver with NaCl particles in the absence of UV, which is different than the case of bare silver.
Bio
Don got his B.E. in materials science and engineering from Hefei University of Technology, China in 2002. He joined Fontana Corrosion Center (FCC) in Oct. 2004 and has been involved in several projects since then. His main interests include general electrochemistry, aqueous corrosion of Ni-based alloy, and atmospheric corrosion. This project is in collaboration with Prof. Heather Allen from the Dept. of Chemistry.
