Effect of Sericite-Molybdenum Disulfide System on Screw Lubricants Performances under High Temperatures

Abstract

Sericite, molybdenum disulfide (MoS₂), melamin cyanuric acid adduct (MCA), and their mixtures were investigated as lubricants for the screw applied at high temperature, when appropriate solid lubricant was added to the mineral oil and/or to the lithium soap grease. In the process of tightening and loosening of the bolt-nut at room temperature, MoS₂ and MCA produced low torque coefficient, but their values fairly increased after the 5h heat treatment at 800°C. Sericite and its mixture with MoS₂ resulted in lowering or almost at constant loosening torque before and after the heat treatment.
In the high speed four-ball tests, better results were realized from the sericite-added grease than from the graphite-added grease. Sericite showed almost the same extreme pressure property as MoS₂ did when used together with EP agent containing sulfur and phosphorus.