Créé le : 08/09/2010 - Mis à jour le : 23/10/2012
M. Meheux, C. Minfray, F. Ville, Th. Le Mogne, A.-A. Lubrecht, J.-M. Martin, H.-P. Lieurade - Proceeding of the institution of Mechanical Engineer - Part J, Journal of Engineering Tribology
Lubricant formulations for manual gear box applications are optimized for gear contacts although rolling element bearings are lubricated with the same fully formulated oil. This may cause fatigue related damage to these bearings. Several explanations can be considered, but this work focuses on the effect of additives contained in the lubricant.
Rolling contact fatigue tests were performed on a twin-disc machine (TDM). Artificial dents generated by a Rockwell penetrator were made on the faster surface in order to accelerate the fatigue phenomena. Then, pure rolling and 6.7 % slip (SRR) tests were performed with the different lubricants (pure base oil, fully formulated oil and base oil with detergent and anti-foam). Fatigue life results and spalling morphologies are compared.
For the sample obtained with the fully formulated oil and 6.7% of SRR, crack analysis was performed. Using Focus-Ion-Beam Technique (FIB), a spalled sample was milled to reveal a cross-section of a crack. SEM images were taken and EDX analyses along the crack were performed. Additive elements are detected up to the crack tip. AES depth profiling was also performed in the tribofilm generated on the disc surface. The role of additives in rolling contact fatigue is discussed in the light of these results.
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