Article
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Investigation on Graphene Platelet Based Dry Lubricating Film Formation in Tribological Contacts
Version 1
: Received: 25 December 2023 / Approved: 26 December 2023 / Online: 26 December 2023 (10:19:23 CET)
A peer-reviewed article of this Preprint also exists.
Pape, F. Investigation of Graphene Platelet-Based Dry Lubricating Film Formation in Tribological Contacts. Coatings 2024, 14, 360. Pape, F. Investigation of Graphene Platelet-Based Dry Lubricating Film Formation in Tribological Contacts. Coatings 2024, 14, 360.
Abstract
The application of dry lubrication in rolling contacts is challenging due to wear. In previous studies graphene platelets applied as dry lubricants on the surfaces of angular contact ball bearings demonstrated superior properties. These specific bearings, experiencing both rolling and spinning motion, create more severe conditions for dry lubricants. The applied graphene platelets have a thickness of few graphene layers in the nm range and a diameter in the µm range. Such platelets can be produced by mechanical exfoliation from graphite. To delve deeper into the lubrication effects, investigations were carried out using a milli tribometer. In the tests, a fixed steel ball is sliding against an oscillating counterpart under defined load. During the measurements, the applied load and tangential forces on the ball are recorded to calculate the friction. In our case, a steel ball with a diameter of 6 mm was used against graphene-based films on flat bearing surfaces (axial bearing washer). Comparative investigations included nano graphite particles and fullerene as dry lubricants, in addition to graphene platelets of various staple thicknesses. To increase the adhesion of the films to the surfaces, a pre-rolling process was implemented. Afterwards, the friction on the compressed films was measured. The results indicate that the pre-rolling process effectively reduces the friction of the system. After testing, the surfaces underwent analysis using laser scanning microscopy to assess the formed films, wear, and material transfer. It has been demonstrated that the pre-rolling process leads to the formation of a very thin compacted film with surface protective properties. On the ball as counterpart, the graphene platelets generate a transfer film on the contacting surface.
Keywords
Graphene platelets; fullerene; nano graphite; dry lubrication; tribological contact; transfer film
Subject
Engineering, Mechanical Engineering
Copyright: This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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