| 摘要 |
PROBLEM TO BE SOLVED: To easily reproduce the generation of sludge in an actual device in a short period by adding a shearing stress to a lubricating oil, and heating it in the presence of oxygen. SOLUTION: As lubricating oil, 100-500 ml of turbine oil is used, and a shearing stress is added, in the case by mechanical means, at a shearing speed of 10<4> -10<7> S<-1> for 10-100 hours and, in the case by ultrasonic waves, at a frequency of 8-15 kHz and a wavelength of 20-30μm for 4-10 hours, and the temperature of the lubricating oil during it is preferably set to 30-50 deg.C. As the device for transmitting ultrasonic waves, a device capable of keeping the frequency and wavelength constant is preferably used. As the device for mechanically adding the shearing force, a device capable of moving both or one of matters nipping the lubricating oil to keep the shearing speed constant is preferably used. The heating of the lubricating oil is preferably performed at 130-170 deg.C for 50-100 hours in a thermostat device capable of making oxygen coexistent. After the heating, the lubricating oil cooled to near room temperature is filtered to filter the sludge, and the sludge quantity is measured.
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