METHOD OF DETERMINATION OF THERMAL OXIDIZING STABILITY OF LUBRICANTS Russian patent published in 1996 - IPC

FIELD: measurement technology. SUBSTANCE: method of determination of thermal oxidizing stability of lubricants involves heating of materials in the presence of air, mixing and determination of parameters of evaluation of oxidation process. Two samples of lubricant are subjected to heating separately, each is heated simultaneously with mixing performed with the aid of mechanical device. Optical density of tested lubricant determined by photometry before and in process of heating is used as parameter of evaluation of process of oxidation. First sample is heated at determined time intervals to certain temperature with increase of temperature at start of interval with its holding for the course of interval. Optical density is found at finish of time interval. Graphical dependence of optical density on oxidation temperature is plotted and temperature of start of oxidation is determined by its inflection point. Then second sample is heated to temperature exceeding temperature of start of oxidation found by first sample, is held at achieved temperature for determination of optical density at certain time intervals. Graphical dependence of relation of optical density of oxidized lubricant to optical density of starting lubricant on oxidation time is plotted. Rate of formation of soluble oxidation products is determined by tangent of inclination angle of dependence to X-axis ahead of inflection point of dependence. Rate of formation of unsoluble products is found by tangent of inclination angle dependence to X-axis after inflection point. EFFECT: enhanced authenticity of determination of oxidizing stability of lubricants. 3 dwg, 2 tbl