Thermal-oxidative stability of lubricating greases

This article presents data from an investigation of the thermal-oxidative stability of silica gel and phthalocyanine greases formulated with the base fluids Kh-2-1-VV polymethylchlorophenylsiloxane and PEF-240 perfluoropolyester. The dependence of the rheological properties of the greases on the content of thickening agent was examined. The thermal-oxidative stability was studied in a Dupont thermal analyzer, using a differential scanning calorimeter and a thermogravimetric analyzer in the programmed heating regime (10/sup 0/C/min) with an air purge rate of 70 ml/min and a sample weight of 9.8-10 mg. It is determined that the thermal-oxidative stability of the silica gel greases based on the KhS-2-1-VV fluid is determined primarily by the properties of the dispersion medium, and the temperature of initial oxidation of the greases corresponds to the temperature of initial oxidation of the KhS-2-1-VV fluid (315/sup 0/C). While the PEF-240 has a higher thermal-oxidation stability than the KhS-2-1-VV fluid, a comparison of the kinetic characteristics (reaction rate constant and half-decomposition period) shows that the stability of the phthalocyanine grease based on KhS2-1-VV is considerably higher than that of the silica gel grease based on PEF-240.