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Tribology Letters

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01-12-2022 | Tribology Methods

Novel In-Situ Observation of the Grease Constituents in Elastohydrodynamic Contacts by Fluorescence Microscopy

Authors: David Kostal, Michal Okal, Josef Fryza, Ivan Krupka, Martin Hartl

Published in: Tribology Letters | Issue 4/2022

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Abstract

Grease is important lubricant for ball bearings as it is used much more often than oil. However, mechanism of the lubrication is not completely clear, especially concerning the role of the thickener in the lubricating process. It was shown that contribution of the thickener to film thickness build-up varies with operating conditions. Also, its influence on the resistive torque of the bearing was proved. However, all studies were in-direct showing its effects. This paper presents new in-situ fluorescence method of the grease constituents’ observation, where both, thickener, and base oil can be observed independently. Two different fluorescence dyes are used to distinguish grease constituents with the use of different microscope setup. Moreover, the new method was tested on two different test rigs. First is typical ball on disc test rig widely used for study of elastohydrodynamic lubrication. Second is ball on ring test rig which more closely represents radial ball bearing conditions. It was shown that thickener engagement is very different for each geometrical configuration.

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Title: Novel In-Situ Observation of the Grease Constituents in Elastohydrodynamic Contacts by Fluorescence Microscopy
Authors: David Kostal
Michal Okal
Josef Fryza
Ivan Krupka
Martin Hartl
Publication date: 01-12-2022
Publisher: Springer US
Published in: Tribology Letters / Issue 4/2022
Print ISSN: 1023-8883
Electronic ISSN: 1573-2711
DOI: https://doi.org/10.1007/s11249-022-01671-7

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