AVS 46th International Symposium
    Applied Surface Science Division Tuesday Sessions
       Session AS-TuP

Paper AS-TuP4
Reaction of Fluorocarbon Contaminants with Aluminum Oxides: Inadvertant Fluoride Formation during Low Temperature Plasma Cleaning of Aluminum Alloy Surfaces

Tuesday, October 26, 1999, 5:30 pm, Room 4C

Session: Poster Session
Presenter: C.E. Moffitt, University of Missouri, Kansas City
Authors: C.E. Moffitt, University of Missouri, Kansas City
D.M. Wieliczka, University of Missouri, Kansas City
C.M. Reddy, University of Missouri, Columbia
Q. Yu, University of Missouri, Columbia
H.K. Yasuda, University of Missouri, Columbia
Correspondent: Click to Email
Plasma deposited films have shown promise as intermediate adhesion and barrier layers for use in the interface engineering of corrosion protection systems on various materials. The surface treatment of plasma deposited trimethylsilane (TMS) films with fluorocarbon plasmas has been seen to significantly improve the adhesion of certain paints to these films, which are strongly adhered to underlying aluminum alloy substrates. Oxygen plasma cleaning of the alloy surfaces, prior to deposition of the TMS film, is normally employed to remove organic contaminants. During testing, one batch of aluminum panels was processed without the oxygen plasma treatment and exhibited extensive adhesion failures. An investigation of these results shows that low levels of fluorocarbon contaminants readily react with the alloy surface and deposit a carbonaceous layer, which dramatically interferes with the adhesion of the plasma polymer to the alloys. XPS studies show that the presence of even low levels of these contaminants in the chamber, during the oxygen cleaning process, is sufficient to induce the conversion of the surface from oxide to a mixture of oxide and fluoride. When present, this fluoride layer is found to reduce the corrosion resistance of test panels. Support for this work was provided by DARPA under U.S. Air Force contract F33615-96-C-5055.