Humdity dependence of the tribological behavior of diamond-like carbon films against steel ball

摘要

Diamond-like carbon (DLC) films deposited on Si(100) wafer by r.f.-plasma assisted chemical vapor deposition were friction tested by ball-on-disk type tribometer invarious test environments in various test environments. The friction tests were performed in an ambient air of relative humidity ranging from 0 to 90% or dry oxygen environment. We focused on the tribochemical reactions by analyzing the chemical composition, chemical bond structure adn agglomerated shape of the debris. High and unstable frictional behavior was boserved in both humid air and dry oxygne environment. In these environmetns, Auger spectrum analysis showed that the debris contained large amonut of Fe.Significant incorporation of Fe in the debris resulted from the wear of the steel ball, which might be enhanced by the surface oxidation of the ball. However, a very low frictioanl coeffecient was oserved against the sapphire bal even in dryincreased Fe concentration in the debris. Hence, the humidity dependence of the frictional coefficient is not an inherent tribological property of DLC film but results from the surface reaction of the frictional coefficient is not an inherent tribological property of DLC film but results from the surface reaction of the steel ball with humid environment. Two possible reasons for the Fe rich debris to affect the frictional frictional behavior were suggested.