Stability and lubricity of zinc dithiomolybdenate at elevated temperature

Zinc dithiomolybdenate was prepared in laboratory and evaluated as a high temperature lubricant on an MG-200 high temperature friction and wear tester. The thermal stability of the compound was examined by thermogravimetric analysis. The chemical states of S, Mo and Zn on the lubricated Sialon ceramic surface were determined by means of X-ray photoelectron spectroscopy. Zinc dithiomolybdenate begins to decompose at 249.8 °C in air. A low friction coefficient was obtained for Sialon ceramic ball/W18r4V steel disk frictional pair under the lubrication of zinc dithiomolybdenate as a solid lubricant below 500 °C, and it increases with the increase of temperature. At the temperature over 500 °C, S and Mo are oxidized during the friction process, with the generation of ZnSO₄, ZnS and MoO₃.