Abstract
Physical properties of lubricants under high pressure (e.g., density, elastic constant and viscosity) are the fundamental properties for the tribological evaluation (i.e. friction and wear) of rolling bearings, gears and traction drives. This paper introduces the importance of such physical properties of lubricants under high pressure in tribology and the application of a diamond-anvil pressure cell (DAC) for tribological measurements. A falling sphere viscometry in the DAC facilitated the viscosity measurements up to 2 GPa. A photon-correlation technique with laser light scattering in the DAC enabled the viscosity estimation of solidified glassy state lubricants (viscosity is about 109 Pa·s) from structural relaxation. Dynamic elastic moduli were obtained from Brillouin light scattering measurements in the DAC up to 4 GPa, which enabled the evaluation of the frequency dispersion of elastic moduli with quasi-static data.
