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

Paper SS-WeP25
An UHV Analytical Tribometer to Evidence Tribochemistry

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

Session: Surface Science Poster Session
Presenter: T. Le-Mogne, Ecole Centrale de Lyon, France
Authors: T. Le-Mogne, Ecole Centrale de Lyon, France
J.M. Martin, Ecole Centrale de Lyon, France
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Increasing demands in the mechanisms of lubricant additives and thin films have resulted in the development of new tribometers coupled with surface analysis techniques. In this paper the so-called AES/XPS analytical tri botester is presented. In-situ surface analyses inside and outside wear scars without air exposure are possible thanks to a tribometer directly installed in the UHV analytical chamber. Two experimental approaches are developed to study the tribochemical reactions of lubricant additives. The first one consists in UHV friction experiments on tribological films previously formed. Thanks to AES and XPS mapping, the good friction reducing properties of molybdenum dithiophosphate (MoDDP) are explained by the formation of MoS2 in the sliding contact. The second one studies the reactivity of fresh surfaces with gaseous compounds which are chemically representative of lubricant additives. Interesting results have been obtained by comparison between 1-hexene and n-hexane on steel at different partial pressures.