In situ Observation of Lubricant Film at EHL Contact using Micro-FTIR

摘要

The concentration of additive in lubricants at elastohydrodynamic lubrication (EHL) contact was investigated by means of in situ observation with a micro-Fourier Transform Infrared Spectrometer (micro-FTIR). In this study, greases containing thickeners and base oil were used as samples. Micro-FTIR has been used in conjunction with a ball-on-disk lubrication tester. The lubricant film was analyzed by micro-FTIR under a dynamic condition. There are two characteristic peaks, C-H stretching mode at 2850-3000 cm~(-1) and N-H stretching mode at 3000-3500 cm~(-1) originated from base oil and urea thickener, respectively. The concentration of thickener was estimated from these IR characteristic peaks. The results show that the concentration of thickener at the Hertzian contact region increased and was dependent on the urea thickener. On the other hand, infrared spectra in hydrostatic pressure were obtained using a diamond-anvil cell. It was confirmed that the hydrogen bonding of urea thickener was stabilized under high pressure.