As a first step to develop a method of in situ analysis of tribological behavior under oil lubrication, surfaces after the tribo-test with the remaining lubricating oil were analyzed with Raman spectroscopy. A ball-on-disk type tribo-test using a S45C disk and a SUJ2 ball was performed, and then its friction track of the disk surface was analyzed by Raman spectroscopy. Polysulfide and mineral oil were used as the lubricating oil without dilution. In addition to each lubricant peak, iron disulfide (FeS2) tribofilm peaks were detected on the friction track in the case of polysulfide, whereas the magnetite (Fe3O4) peak was detected on the friction track in the case of mineral oil. FeS2 intensity increased overtime in the case of the test at 200°C. In this way, tribofilm and oxide were detected as the remaining lubricating oil by Raman spectroscopy, which therefore suggests that Raman spectroscopy is an effective analysis method to investigate the formation process of tribofilm and oxide under oil lubrication.
This paper investigates the magnitude of the load-carrying capacity enabled by textured feature in hydrodynamic lubrication. The numerical model is a two-dimensional fixed pad bearing with a single dimple. The Reynolds equation was numerically solved using the Elrod algorithm. Two boundary conditions at the inlet and outlet were compared: a periodic boundary condition and an atmospheric boundary condition. The load-carrying capacity for the atmospheric boundary condition is negative while that for the periodic boundary condition is positive when a dimple is located at the centre of the lubricated area. The atmospheric boundary condition, when a dimple is located on the inlet side and is opened to the outside, exhibits greater load-carrying capacity than that in the enclosed dimple case.