Viscosity Measurement of Lubricants under High Pressure

Abstract

The pressure-viscosity relation of lubricants, which is important in elastohydrodynamic lubrication, was examined with a diamond-anvil high-pressure generationg apparatus which can produce a pressure of up to 100 GPa. Owing to the optically transparent property of diamonds, the crystallization of lubricants could be observed and their pressure was measured by the ruby fluorescence method, in which the linewidth broadening over the viscosity of 10¹² Pa·s was used in determining glass transition pressure. The results were compared with the existing values, and the correlation between the glass transition pressure this method to the study of tribology.