Effect of Substrate Surface Finish on the Lubrication and Failure Mechanisms of Molybdenum Disulfide Films

Abstract

An optical microscope was used to study the lubrication and failure mechanisms of rubbed (burnished) MoS₂ films applied to three substrate surface finishes—polished, sanded, and sandblasted—as a function of sliding distance. The lubrication mechanism was the plastic flow of thin films of MoS₂ between flat plateaus on the rider and on the metallic substrate. If the substrate were rough, flat plateaus were created during “run-in” and the MoS₂ flowed across them. Wear life was extended by increasing surface roughness since valleys in the roughened substrate served as reservoirs for MoS₂ and a deposit site for wear debris. In moist air, the failure mechanism was the transformation of metallic-colored MoS₂ films to a black, powdery material that was found by X-ray diffraction to consist primarily of â-iron and MoO₃ powders. In dry argon, the failure mechanism was the gradual depletion of the MoS₂ film from the contact region by transverse flow. Analysis of the wear debris on the wear track at failure showed it consisted mainly of â-iron and some residual MoS₂ molybdenum oxides were found.

Presented at the 36th Annual Meeting in Pittsburgh, Pennsylvania, May 11–14, 1981

Notes

Presented at the 36th Annual Meeting in Pittsburgh, Pennsylvania, May 11–14, 1981