Atomic oxygen interaction with nickel multilayer and antimony oxide doped MoS(sub 2) films

摘要

Sputtered MoS(sub 2) is a solid lubricant capable of ultralow friction coefficients (below 0.05) load-bearing capacity. Since it exhibits low friction in vacuum, low outgassing rate, is non-migrating and lacks organic binders, this material is an attractive lubricant for space mechanisms. To exploit these new materials to their fullest potential, designers of space-based motion systems require data on the effects of atomic oxygen exposure on dense, sputtered MoS(sub 2). This paper describes the effects of atomic oxygen in low earth orbit on the friction and surface composition of sputtered MoS(sub 2) films. Sputtered multilayer films of MoS(sub 2) with nickel (0.7 nm Ni per 10 nm MoS(sub 2), for 1 (mu)m total film thickness), and MoS(sub 2) cosputtered with antimony oxide (nominally 2 (mu)m thick) were exposed to 2.2 to 2.5 x 10(sup 20) oxygen/cm(sup 2) over a period of 42.25 hours in earth orbit on the United States space shuttle. Identical specimens were kept as controls in desiccated storage for the duration of the mission, and another set was exposed to an equivalent fluence of atomic oxygen in the laboratory. The friction coefficient in air and vacuum, and the composition of worn surfaces, were determined prior to the shuttle flight and again after the shuttle flight. Results are described.