AVS 57th International Symposium & Exhibition
    Applied Surface Science Tuesday Sessions
       Session AS-TuP

Paper AS-TuP18
XPS Analysis of Surface Films Formed on Common Metals on Exposure to Ethanol-Blended Fuels

Tuesday, October 19, 2010, 6:00 pm, Room Southwest Exhibit Hall

Session: Applied Surface Science Poster Session
Presenter: H.M. Meyer III, Oak Ridge National Laboratory
Authors: H.M. Meyer III, Oak Ridge National Laboratory
S.J. Pawel, Oak Ridge National Laboratory
Correspondent: Click to Email
Most automobile fuels contain some amount of ethanol, typically around 10% by volume, and fuels with higher ethanol levels are available. In Brazil mandated ethanol levels are 25% (E25 fuel) and in 2009 over 9 million vehicles were on the road using pure ethanol (E100) as fuel. Certainly, in the years ahead increasing levels of ethanol will be available in US fuels. As such, most automobile manufacturers are producing engines that can handle a variety of ethanol-blends. This poster examines several common metals used in fuel storage and fuel handing equipment, namely brass, galvanized steel, and nickel, and compares unexposed material to material that has been exposed to (1) reference gasoline and (2) E10 fuel and (3) E25 fuel. Samples were cleaned (acetone + ultrasonic), weighed, and placed in a stainless steel vessel. Fuel was added and the vessel was purged with Ar and sealed. After raising the temperature to 60 C, the samples were left for 28 days. Upon removal, the samples were rinsed with pure ethanol, dried, and weighed. X-ray photoelectron spectroscopy was used for determining surface composition. Sputter profiling was used to monitor changes in composition as a function of depth. For some samples, XPS mapping was employed to determine lateral distribution of chemical species. Results presented in this poster clearly show greater oxidation and the formation of metal sulfide species for the ethanol-blended fuels as compared to the reference gasoline. Increasing the ethanol content above E10 to E17 showed an increase in the extent of oxidation and formation of metal sulfides.