Tribotechnical Characteristics of Lubricant under Conditions of High Temperatures

This article discusses the issues of maintaining operability of hinged friction joints operating at 500°C. The object of study is the hinged joint of a pipe dryer operating contact loads in the friction joint up to 100 kN and operation temperatures in the range from 200 to 500°C. The studies have been performed with WOLFRAKOTE TOP FLUID high temperature lubricant comprised of solid lubricants suspended in base mineral oil. The experimental results of the lubricating composition upon heating in mold have demonstrated that burn up of the liquid component is intensified at 450°C being accompanied by transfer of lubricating medium into powdered form. Assessment of changes in tribological properties of high temperature lubricant in various aggregate states has demonstrated that heating and transfer of lubricant from liquid to solid state at low contact loads and velocities does not impair its tribotechnical properties. However, the increase in load and velocity parameters causes sharp increase in friction forces with the use of lubricating medium in powdered form. Based on the performed studies recommendations are presented aimed at improving the operability of hinged joints operating at higher temperatures.