Research Reports 2005@Up date@2006.7.10
Abstracts of
Papers
- High-Pressure Viscosity
Measurements of Traction Oils up to 2 GPa at up to 200 [in Japanese], Yuichi
NAKAMURA, Kazuyuki SANDA* and Hideki MATSUBO*: Journal of Japan Society of
Tribologists, 50-4 pp. 354-359, 2005
High-pressure viscosity was measured for
synthetic traction oils including a CVT oil up to 2 GPa at elevated
temperature up to 200 employing a falling sphere method in a diamond-anvil
pressure cell (DAC) with appropriate heating system. The obtained results
almost showed the linearity between logarithmic viscosity and pressure at all
temperature (40`200) with some data scattering. The accuracy of this high
pressure viscometry was confirmed with the existing data at low pressure.
Viscosity-pressure coefficient Ώ decreased to 1/3`1/4 at 200 of that at 40.
Simple experimental expression of temperature depending Ώ was suggested
referring to Eyring viscosity formula. Pressure temperature phase diagrams of
liquid-solid transition were plotted from the obtained high pressure
viscosity, which predict traction feature.
- Micro-Rheometry of
Pressurized Lubricants and Micro-Nanorheology, Yuichi NAKAMURA, Yasushi
KUROSAKI: Microsystem Technologies, Special Issue: JSME-IIP/ASME-ISPS Joint
Conference 2003 Yokohama, 11, pp. 1127-1131, 2005
In the present study, micro-rheometry of
pressurized lubricants employing a diamond-anvil pressure cell and a laser
confocal displacement sensor of 0.4Κm resolution was shown. High pressure
viscosity was obtained up to 2 GPa at 200 for traction oils and PFPE oils.
Viscosity-pressure coefficient Ώ at room temperature was almost twice larger
than that at 100 . Ώfor hard disk oil, Zdol2000, was 13 /GPa at 24 ` 5 /GPa
at 150 and was similar to that of paraffinic mineral oil. The feature of the
obtained high pressure volume was different for each oil up to 6 GPa. Zdol2000
was the most compressible of all the sample lubricants and its high pressure
refractive index increased about 10 % at 4.8 GPa. Zdol2000 remained
transparent up to 4.8 GPa under isothermal loading. Some considerations for
lubricant's micro-nanorheology were also mentioned with high pressure
lubricant's rheology.
- Evaluation of
Quasi-Static Density and Elastic Modulus for Pressurized Lubricant Oils up to
5 GPa Considering Volume Viscoelasticity, Yuichi NAKAMURA, Yasushi KUROSAKI
and Nobuyoshi OHNO*: Book of Synopses International Tribology Conference Kobe 2005, pp.
171, 2005
Quasi-static pressure-dependence equations of
density and elastic modulus for lubricant oils were derived up to 5 GPa based
on the experimental data from both quasi-static pressure vessel apparatus up
to 1.2 GPa and dynamic sound velocity data by Brillouin light scattering
measurements up to 5 GPa. Dynamic data were analyzed by applying a
viscoelastic model for volume change and quasi-static data were obtained.
Examined lubricant oils were 3 naphthenic oils such as traction oils, 5P4E
(five-ring polyphenyl ether) and DOS (dioctylsebacate). Lubricant oils whose
solidified pressure is lower than 1 GPa were resulted to show almost the same
pressure-dependence characteristics of density and bulk modulus over
solidified pressure. Temperature-dependence of these equations found out to be
small up to 155 .
-
Plastic Deformations of Micro-spheres by Solidified Lubricants and Lubricants'
Shear Stress under Very High Pressure, Yuichi NAKAMURA, Masanori SHIMAOKA,
Yutaka ISHIBASHI* and Masahito MATSUI: Proceedings of WTC2005 World
Triborogy congress III, CD, 63099, 2005
In order
to grasp the possibility of evaluating shear properties for solidified
lubricants under high pressure, plastic deformations of metal micro-spheres
(about 0.07mm) in solidified lubricants were evaluated by employing a diamond-
anvil pressure cell (DAC). Large deformations (2-5 times larger than the
original sphere dimensions) were observed for CVT oil and ester oil up to 6
GPa at 23-25. Deformation starting pressure agreed with the solidified
pressure. These deformations were caused by the non-hydrostatic pressure in
the solidified lubricants. Shear stresses of the solidified lubricants were
tentatively and roughly estimated from the plastic deformations of the spheres
based on some assumptions. They almost agreed with the mean shear stress
(traction force / hertzian contact area) from traction test.
- High-Pressure Viscometry
and Dilatometry for Lubricant Oils in a Diamond Anvil Cell Up to 6 GPa, Yuichi
NAKAMURA, Kazuyuki SANDA* and Hideki MATSUBO*: Proceedings of WTC2005 World
Triborogy congress III, CD, 63100, 2005
To measure the properties of lubricant under high pressure, a
diamond?anvil pressure cell was employed. With a falling sphere viscometry,
viscosities were measured up to 2 GPa at up to 200 for traction oils. The
results showed linearity between logarithmic viscosity and pressure at any
temperatures. At 200, lubricant viscosity-pressure coefficient fell to
between 1/4 and 1/3rd of the value at 40. A simple expression for the
dependence of high pressure viscosity on temperature has been suggested.
Pressure temperature phase diagram of liquid?solid transition was plotted from
the obtained viscosity. The change in volume due to solidification was
estimated up to 6 GPa.