METHOD FOR DETERMINING THERMAL OXIDATIVE STABILITY AND TEMPERATURE RESISTANCE OF LUBRICATING MATERIALS Russian patent published in 2019 - IPC G01N25/02 G01N33/30 

FIELD: measurement technology.

SUBSTANCE: invention relates to technology of assessing quality of liquid lubricants. Disclosed is a method of determining thermo-oxidative stability and temperature resistance of lubricating materials, in which samples of lubricant material of constant mass are tested in the presence of air at temperatures below critical, selected depending on base, lubricant assignment and group of operational properties, during the time, which characterizes the same oxidation degree. Novelty is that lubricant sample tests are carried out at one or more temperatures, wherein at regular intervals the temperature-controlled lubricant sample is weighed, mass of evaporated lubricant is determined, part of sample is taken for direct photometry and determination of optical density, part of sample is used to determine kinematic viscosity. Coefficient of thermal oxidative stability is calculated as the sum of optical density and evaporation rate, the index of thermooxidative stability is determined as product of optical density by viscosity index or as product of thermal-oxidative stability index by viscosity index. Graphical dependences of the thermo-oxidative stability index on the optical density or on the thermal oxidative stability coefficient are plotted, and the effect of the base of the lubricant is determined from the inclination angle to the abscissa axis, test temperature, oxidation products or thermal decomposition or together oxidation products and temperature decomposition by the viscosity index value, wherein larger tangent of dependence angle, higher viscosity index at pre-set optical density.

EFFECT: high information value of the method of determining thermo-oxidative stability and temperature resistance of lubricating materials by taking into account the effect of temperature, oxidation, evaporation, temperature decomposition and viscosity-temperature characteristics.

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