METHOD OF DETERMINING THERMAL OXIDATIVE STABILITY OF LUBRICANT MATERIALS Russian patent published in 2016 - IPC G01N25/00 

FIELD: chemistry.

SUBSTANCE: invention relates to determination of quality of lubricating oils, in particular to determination of effect of oxidation products on viscosity index. Method of determining thermal oxidative stability of lubricant materials, wherein lubricant sample is tested in presence of air with mixing of constant volume at optimum temperature, selected depending on base of lubricant and group of operational properties. Oxidised lubricant material is sampled at equal time intervals, photometry is used to determine light flux absorption coefficient, kinematic viscosity and oxidation process is assessed according to invention. Method includes additionally determining kinematic viscosity of oxidised lubricant material at temperature of 40 and 100 °C, based on which viscosity index is determined, a curve of viscosity index versus light flux absorption coefficient is plotted, from which thermal oxidative stability of lubricating material during oxidation is determined. Value of viscosity index at given light flux absorption coefficient increases with thermal oxidative stability of tested lubricating material.

EFFECT: high reliability of evaluating quality of lubricating oil for various purposes and viscosity grades by taking into account effect of oxidation products on viscosity index.

1 cl, 1 dwg, 1 tbl