High-Pressure Viscometry and Dilatometry for Lubricant Oils in a Diamond Anvil Cell Up to 6 GPa

Abstract

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 °C for traction oils. The results showed linearity between logarithmic viscosity and pressure at any temperatures. At 200 °C, lubricant viscosity-pressure coefficient fell to between 1/4 and 1/3rd of the value at 40°C. 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.