Under severe bearing conditions, deposits form on the loaded part of bearing pads and if this happens excessively, it could lead to unacceptable rises in temperature and vibration. Deposits are mainly organic compounds, formed as oxidation by-products, which are insoluble in lubricating oil and can be the precursor to deposits. In this study, the deposit precursor in lubricating oil was investigated in detail and the deposit production mechanism was demonstrated. Furthermore, the difference of oil type effects and the dependence of conditions on deposit formation are also considered.
1. Introduction
Lubricating oil deteriorates while in service. Severe deterioration, which can occur locally in some cases, can lead to a deposit problem. This could affect the functionality in systems. The problem caused by oil deposits that affects poor lubrication caused by clogging of the lubricant line has been known well. The deposits, however, have some kind of root and visual appearance and composition. Adhesive deposits forming on hot metal surfaces with which lubricating oils are in contact is one of them and the most well-known. They can be observed in the sump and oil lines of gas turbines, rings/liners of diesel engines and oil lines of turbochargers; all of which have surfaces at temperatures exceeding 300°C. Such deposits are due to the remarkable thermo-oxidation reaction of oils on hot metal surfaces and can be controlled by selecting proper oils with high thermo-oxidation stability and reducing the metal surface temperature [1-4].
