Influences Of Diurea-based Grease Composition And Process On The Performance Of High-temperature Hardening

Diurea-based grease is one kind of the most promising lubricant in the 21th century with high operating temperature and long life. With adding the additives of extreme pressure and antiwear agent, rust inhibitor and antioxidant, it can be widely used in many industries, such as automobiles, metallurgy, railway, bearings and so on.But on the other hand, diurea-based grease had some disadvantages. For example, after experiencing at a high temperature, it hardened gradually. This appearance was closely related with the type of raw material and preparation process.In this paper, diurea-based grease was prepared with various kinds of thickening agents, base oils and additives. The hardening tendencies at different temperature were studied with the analytical method of penetration determination, dropping point determination, infrared spectrum and SEM. The results were as follows:(1) At the temperature of 100℃, the lower the viscosity of base oil, the more obvious the hardening trendency of diurea-based grease was appeared. But at a high temperature of 180℃,the viscosity of base oil had little effect on the hardening trendency of diurea-based grease.(2) Different types of base oils had different influences on the high-temperature hardening tendencies of diurea-based greases. Alkyl naphthalene base oil led diurea-based grease to hardening. Ester oil led diurea-based grease to softening. Mineral oil had little effect on the hardening trendency of diurea-based grease.(3)The diurea-based grease which was prepared from cyclohexylamine hardened uniformly inside and outside. The diurea-based grease which was prepared from octylamine and aniline was hardened serious at surface. The diurea-based grease which was prepared from octadecylamine became softened at high temperature and then became hardened after cooling. The diurea-based grease which was prepared from octylamine and cyclohexylamine had low hardening tendency.(4) Active additives had different influences on the high-temperature penetration of diurea-based greases. At the condition of 120℃, T202 led diurea-based grease to hardened, TCP led diurea-based grease to softened, while T321 had little influence on diurea-based grease. Inert additives had a weak softened effect on the diurea-based grease at high-temperature.(5) The refining temperature had certain influence on the hardening tendency of diurea-based grease. The higher the refining temperature, the lower hardening tendency of diurea-based grease was appeared. At 180℃, the structure of the diurea-based grease was becoming steady. After dispersing by shearing, the penetration of diurea-based grease became steady. The dispersing by shearing could help to reduce the hardening tendency.