Evaluation of Tribological Characteristics of Sputtered MoS(sup 2) Films Exposed to the LEO Environment.

摘要

Three kinds of sputtered molybdenum disulfide (moS2) films were exposed to the low earth orbit (LEO) space environment aboard the NASA Space Shuttle (STS-85) for 11 days, as a part of the Evaluation of Space Environment and Effects on Materials (ESEM) experiment. For comparison, the same types of MoS2 films were exposed to atomic oxygen (AO) or ultraviolet rays (UV) on the ground. Surface analyses and friction tests were carried out to evaluate the influence of AO, UV and the LEO space environment on the tribological characteristics of the sputtered MoS2 films. The surfaces of all the films exposed to LEO were oxidized. The depth of the oxidized layer differed for each type of film. The friction coefficient of all the films decreased after exposure to the LEO environment. The effect of space exposure on the wear life of the MoS2 films depended on the film type. AO produced a similar but more profound effect than LEO exposure. The effect of UV irradiation was hardly observed.