A MOLYBDENUM-DISULFIDE MAGNETIC SOLID LUBRICANT FOR FERROMAGNETIC SURFACES

Molybdenum disulfide (MoS2) has been used ill industrial applications as a dry lubricant. Although this material initially improves anti-wea r properties, as surfaces move against each other the lubricating part icles tend to spread out from the asperity points, To reduce this spre ad of lubricant, MoS2 platelets were made magnetic by replacing the un saturated or loosely bonded sulfur atoms (located mainly on the edges of Ore platelets) with magnetic elements such as Fc, Ni, or Co particl es. Under appropriate experimental conditions these elements form stab le bonds with the partially free Mo atoms of the edges and are protect ed from oxidation in air by the basal planes of the overlapping neighb oring layers. When compared to the friction coefficient of pure MoS2, the incorporation of magnetic Fe particles for example, increases the friction depending on The Fe/Mo ratio, but the overall result is in an improved lubricant with unique magnetic properties when the Fe/Mo rat io is properly optimized. In this application at least one of the surf aces must be ferromagnetic to hold the lubricant in place. (C) 1997 Am erican Institute of Physics.