Development of High Temperature Solid Lubricant Coatings.

Abstract : The primary research objective of this work was to develop a solid lubricant coating that can function over a broad temperature range. The approach investigated consisted of developing adaptive lubricant coating from materials that undergo chemical change with increasing temperature by reacting together and with the environment. To test this approach, UES and Cleveland State University have conducted experiments to form cesium oxythiotungstate, a high temperature lubricant, on Inconel 718 surface from composite coatings of cesium tungstate and tungsten sulfide. The coatings were deposited by RF sputtering and characterized by X-ray Photoelectron Spectroscopy (XPS). The results indicate that sulfur escapes from the composite coating upon exposure to temperature above 5000C in air. Thus, the desired adaptive lubricant phase, cesium oxythiotungstate could not be formed. However, cesium oxythiotungstate phase has been found to form upon annealing at high temperature in vacuum. The friction coefficients of sputtered cesium oxythiotungstate and cesium tungstate coatings have been measured.