Rolling contact fatigue studies on AISI 4140 steel under formulated lubrication conditions with nano graphene additives

• Published in: Wear 2024-05, Vol.544-545, p.205311, Article 205311
• Main Authors: Ranju, M.R., Abhilash, P.M., Kesavan, D.
• Format: Article
• Language: English
• Subjects: Graphene nano lubricant; Lubrication mechanism; Rolling contact fatigue; Temperature monitoring; Thermal conductivity
• ISSN: 0043-1648; 1873-2577
• DOI: 10.1016/j.wear.2024.205311

This investigation primarily intends to formulate a graphene nano lubricant with various concentrations of graphene additive, then experimentally assess and compare their impact on rolling contact fatigue (RCF) performance of AISI 4140 steel under pure rolling conditions. After formulation, various other parameters including kinematic viscosity, dispersion stability, aggregation behaviour, and thermal conductivity, were examined and the findings were compared. For RCF testing, continued monitoring of contact interface temperature was introduced to analyse the behaviour and mechanism of dispersed graphene particles in the lubricated contacts. RCF performance is significantly impacted by the larger-sized agglomerated graphene particles because they encourage particle sedimentation and pileup at the contact inlet, which decreases particle entrapment to the contact region, reduces surface adsorption and diminishes thermal conductivity effect. Base oil with one percent weight graphene provides better film stability, effective lubrication character and 3 times enhanced RCF life compared to the base oil. •Thermal conductivity (8%) and viscosity (8.7%) of the base oil increased with addition of 1.5% GNP.•RCF testing performed under 1.0% GNP results in a three-fold increase in life.•The amount of graphene particles entrapping at the contact zone determines the improved life.