Experimental Investigation of Lubrication Failure of Polyalphaolefin Oil Film at High Slide/Roll Ratios

Lubrication failure of polyalphaolefin (PAO) oil film at high slide/roll ratios of more than 1.9 has been experimentally investigated based on a ball-on-disc configuration. The central film thickness and the oil pool shape in the contact were determined by optical interferometry and fluorescence microscopy, respectively, and the traction coefficient and surface profiles of the tribopairs were measured using a tension-compression sensor and light surface profilometer, respectively. The results demonstrate that the central film in the contact was in the elastohydrodynamic lubrication regime at the initial stage under high slide/roll ratios. Variation in the traction coefficient and the presence of wear scars on the disc surface shows that the sliding speed played an important role in lubrication failure. We propose that a thermal effect explains the obtained results at high slide/roll ratios. The fluorescence technique combined with optical interferometry was also used to gain more understanding of lubrication properties under mixed slide/roll conditions.