AVS 47th International Symposium
    Surface Science Tuesday Sessions
       Session SS2-TuA

Paper SS2-TuA8
Transient Currents as a Tribological Probe

Tuesday, October 3, 2000, 4:20 pm, Room 209

Session: Stimulated Processes and Excitations
Presenter: J.V. Wasem, Washington State University
Authors: J.V. Wasem, Washington State University
S.C. Langford, Washington State University
J.T. Dickinson, Washington State University
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When conductors contact and slide on insulator surfaces charge transfer between the surfaces allows one to measure instantaneous transient currents (TC). We have instrumented a vacuum tribological apparatus with high sensitivity normal, lateral, and TC pick-up using metal and semiconductor stylii. Performing single pass wear track formation tests on polymer and ceramic substrates, we observe striking correlations between the mechanical and electrical signals. In particular, the TC exhibit fluctuations with a rich temporal/frequency spectrum, for example during stick-slip events. Through correlations with SEM images of the substrate we are able to relate spatial microscopic damage and corresponding TC behavior. The TC reveals details of the micromechanics during wear on microsecond time scales. Studies on Fomblin Zdol lubricated hard drive surfaces reveals charge transfer events that correspond to free electrons going to the lubricant. Yates et al. have previously shown that electron attachment to such polyperfluoroethers can cause decomposition of the polymer. Thus, our studies can provide quantitative values and rates for the charge deposited which can then be used to predict lubricant lifetimes from measured attachment cross-sections.