The lubrication mechanism of cerium dithiomolybdate from room temperature to 600 °C

CCe₂(MoO₂S₂)₃4H₂O was synthesized in our laboratory and the lubrication performance of the compound as a solid lubricant was examined using a ball-on-disc tribometer. It is effective in reducing friction of Sialon ceramic/W18Cr4V steel friction pair from room temperature to 600 °C. Thermogravimetric analysis, X-ray diffraction, scanning electron microscopy and X-ray photoelectron spectroscopy were used to exhibit the lubrication mechanism of the compound. As the results indicated, Ce₂(MoO₂S₂)₃·4H₂O experienced tribochemical reaction during sliding process at elevated temperature, with the formation of MoS₂, which leads to a decrease in the friction coefficient. During the friction process below 400 °C, the element S bonded with Mo in Ce₂(MoO₂S₂)₃ acts to reduce Mo⁶⁺ and generate MoS₂, while during the sliding process at 500 °C, the element S bonded with Ce acts to reduce Mo ⁺⁶ and generate MoS₂.