The research of oil properties after durability tests of porous bearings

Self-lubricating bearings are characterized by sileni-running work, long durability, and high load-carrying capacity at small sliding velocities. Durability of porous sliding bearings is one of the most important parameter determiningfuture implementation. However, during operation loss of self-lubricating capability of the bearing can be caused by aging process of lubricant, what could lead also to decreasing of the durability. Oil aging process could be much deeper than in conventional sliding bearings with solid bushes, because of temperature, catalyst metal - porous stutcture and oxygen accelerating oxidation of oil. It was preliminary confirmed in the previous research that after durability tests of porous bearings high values of total acid number (TAN) of oils samples were achieved. Infrareds (IR) spectrums were also deeply changed. Thus the same investigation was performed for two other different oils (mineral gear oil and perfluorinatedpolyether - PFPE). After the durability test oil samples were unsaturated from the bearings and IR spectrums and TAN were examined. As it appeared change of mineral gear oil properties were not very deep. On the other hand synthetic PFPE oil had high TAN values and significant differences in the IR spectrums were observed.