Technical Committee Lubricants

Influence of Antioxidants on the Lubricating Grease Service Life of High-Speed Rolling Element Bearings

For mechanical engineering purposes, rolling element bearings are mainly lubricated with grease. Up to now knowledge about the behaviour of grease containing antioxidants is neither sufficient nor complete, in particular with respect to their application range, speed limit, and influence of the antioxidants on boundary layers in the rolling contact.
This research project investigated the influence of antioxidants on grease properties and grease service life as well as their impact on boundary layers. Six batches of grease were tested consisting of the same basic grease in combination with four different antioxidants and a mixture of two of these antioxidants. The results show that antioxidants have a significant influence on grease service life. Furthermore, time-of-flight secondary ion mass spectrometry, infrared spectroscopy, nano hardness measurement, and scratch tests were employed to analyse the influence of antioxidants on grease properties and boundary layer composition.