Wear protection of extreme pressure/anti wear additives influenced by corrosion inhibitors in oil-lubricated rolling bearings

Wear protection in rolling bearings is heavily dependent on the lubricant. Therefore, extreme pressure / anti wear (EP/AW) additives are added to the lubricant to ensure low-wear operation of the bearing. These surface-active additives form tribological boundary layers (TBL) on the metal surfaces, which can prevent wear. However, commercially available lubricants also contain surface-active corrosion inhibitors (CI), which can influence the formation of TBL and thus the wear protection of EP/AW. To examine the influence of CI on the wear protection of EP/AW, tests on an axial thrust bearing test rig and chemical characterization of the TBL have been carried out. The results show synergistic as well as antagonistic influences on wear protection of EP/AW depending on the CI used. • Positive as well as negative effects of corrosion inhibitors on the wear protection of extreme pressure / anti wear additives were observed, which depend on the additive combination. • Electron probe micro analysis (EPMA) results show insightful composition of formed tribological boundary layer