AVS 49th International Symposium
    Surface Science Wednesday Sessions
       Session SS-WeP

Paper SS-WeP26
Coupling of XPS and XANES to Characterize Sulfides in Films Formed from Lubricant Additives

Wednesday, November 6, 2002, 11:00 am, Room Exhibit Hall B2

Session: Surface Science Poster Session
Presenter: M.I. De Barros, Ecole Centrale de Lyon, France
Authors: M.I. De Barros, Ecole Centrale de Lyon, France
J. Bouchet, Ecole Centrale de Lyon, France
T. Le-Mogne, Ecole Centrale de Lyon, France
J.M. Martin, Ecole Centrale de Lyon, France
Correspondent: Click to Email
The nature and properties of each species formed in both the antiwear action of zinc dithiophosphate (Zndtp) and in the friction reduction of molybdenum dithiocarbamate (Modtc) are investigated. Special attention was carried out to the advantage of coupling two surface analytical techniques on the Zndtp, Modtc and Zndtp/Modtc combination tribofilms: XPS and XANES spectroscopies. XANES is a bulk analysis of the film compared to XPS which is much more surface sensitive. A Cameron-Plint friction machine was used to generate large tribofilm areas in mild/severe tribological conditions. First XANES spectroscopy at the P K-edge, Mo K-edge and S K-edge was carried out in order to investigate any differentiation between phosphate and sulfides. Afterwards, an XPS analysis was performed in the same location of the tribofilm. Special attention has been paid to the deconvolution of Fe2p, Zn2p, S2p, Mo3d and O1s photopeaks and Auger ZnLMM lines. Analytical results are discussed and compared with theoretical predictions from the Chemical Hardness model for Zndtp, Modtc and Zndtp/Modtc tribofilm formation.