| Abstract: | Differential thermal analysis (DTA) and thermogravimetry (TG) methods have been developed to evaluate the thermal and thermooxidation stability of different lubricating oils. Measurements are carried out either by heating the oil sample at a constant rate (direct programme) or by keeping it at a fixed high temperature (isothermal programme). Oxygen at a constant flow rate is used for thermooxidation measurements. Tested samples included different viscosity grades: neutral base oils, unadditivated lubricating oil blends, and industrial oils. The mechanism of thermal decomposition for ZDDP and the estimation of its optimum concentration was also considered. |
