Cesium oxythiomolybdate (Cs2MoOS3) is under consideration as a high temperature solid lubricant for silicon nitride bearings. A method of depositing Cs2MoOS3 coatings with precise thickness, good adhesion, and lubricious chemistry was desired.Pulsed laser deposition (PLD) is an excellent method of depositing tribological films, and these films often exhibit superior tribological performance when compared to films deposited by other methods. PLD was chosen as the deposition method for Cs2MoOS3 in this study primarily due to its characteristic of replicating the target chemistry in the film. Using PLD to grow films was expected to simplify identification of the compounds before and after annealing. In addition, the thickness of PLD films can be controlled from a few nanometers to as much as several micrometers. Also,PLD has been found to deposit highly adherent films. When annealed, films oxidized to primarily Cs2SO4 at 300 8C, which decomposed to cesium oxides and SOx below 600℃. Also present at 600℃ were cesium molybdates (including Cs2MoO4), cesium oxides, and molybdenum oxides (including MoO3). All of the solid compounds may be lubricious at elevated temperatures. Films deposited on Si3N4 and annealed to 800 ℃ also contained crystalline SiO2, which indicated the presence of amorphous silicate glass at lower temperatures or when heated for shorter times. The combination of silicate glass and melted cesium oxides at temperatures between 400 and 800 ℃ is likely to create a cesium silicate glass as the cesium ions diffuse into the oxide. This glass may be lubricious at elevated temperatures. Because each of the compounds formed by the decomposition of Cs2MoOS3 films has a different temperature range over which it is lubricious, these compounds may provide continuous lubrication from 300 to 800℃. Pulsed laser deposited Cs2MoOS3 has good potential as a high temperature solid lubricant
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