| Budget Amount *help |
¥3,300,000 (Direct Cost: ¥3,300,000)
Fiscal Year 2006: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2005: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2004: ¥1,800,000 (Direct Cost: ¥1,800,000)
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| Research Abstract |
The main purpose of this research was to obtain high-pressure viscosity data up to 2 GPa at 200℃ for traction oils and 3 GPa at 200℃ for biodegradable vegetable oils employing a diamond-anvil pressure cell (DAC). Themain purpose was almost achieved. Data for a saving energy-type engine base oil were achieved up to 1 GPa at 100℃. Some high-pressure rheological data were listed in web site homepages as databases.
For traction oils, the linearity between logarithmic viscosity and pressure was confirmed. At 200℃, lubricant viscosity-pressure coefficient fell to about l/3rd of the value at 40℃. Simple empirical expressions for the dependence of high pressure viscosity on temperature were suggested based on Eyring formulas and Barus equation. Pressure-temperature phase diagrams, which foresees the feature of pressure depending maximum traction coefficient, was constructed and boundary curves between liquid phase and solid phase were predicted. They were consistent with curves by Ohno et al. a
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nd were extended in wider range to 2GPa and 200℃ than them.
High-pressure viscosity of all vegetable oils and polyol ester featured similar trends and values. The pressure-viscosity coefficients of all oils around the maximum pressure were 7 /GPa at 0.5-1.4 GPa and at 100℃, 3-4 /GPa at 1.8-2.7 GPa and at 200℃. Most vegetable oils showed non-Newtonian behavior over about 10 Pa・s (0.4GPa) at all temperatures and pressures. Finally, oils transited to polycrystal-like phase. During fast pressurization at room temperature, the phase transition did not occur in the vegetable oils.
For a saving energy-type engine base oil, polyalphaorefine (PAO4), high-pressure viscosity was measured after the establishment of a simple pressure evaluation method by DAC loading screw angle. Measured data were consistent with the reference data and their range was extended up to 1 GPa at 100℃. Calibration experiments for several oils proved that this method is applicable up to 150℃.
As for theoretical evaluation of high-pressure viscosity, Yasutomi formula applying WLF equation based on free volume theory was resulted to be appropriate and calculation of free volume by such as molecular dynamic simulation is expected to predict high-pressure viscosity.
As for the web site high-pressure viscosity database, database homepage of 17 papers including Bridgman data, ASME report and the investigator's (Nakamura) data was constructed showing oil name, the range of pressure and temperature. Less
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