PSI - Issue 12

Francesca Curà et al. / Procedia Structural Integrity 12 (2018) 44–51 Author name / StructuralIntegrity Procedia 00 (2018) 000 – 000

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The analysis has been performed considering two standard oils with different viscosity, one for aerospace applications and the second one useful for wind turbines, and a classical grease for bearings. The obtained Pin-on-Disk results show that all lubricants are sensitive to the presence of GNP additives, even if in a substantial different way, and in all cases there is an optimum compound for lubricants that may guarantee a decreasing in the coefficient of friction. Oil 1 that is very fluid shows an improved behaviour from the tribological point of view only for a low percent of GNP. Oil 2 that is much more viscous shows a decreasing of CoF value for all percent of GNP. For as concerns the grease, it is possible to observe that the presence GNP improves the tribological performance of grease, reducing the CoF even for high percent of additive. The comparison for grease between Pin-on-Disk and spline coupling tests emphasizes very interesting results, showing a similar trend in the coefficient of friction in the two cases and an improving for all percents of GNP. This phenomenon can highlight new horizons in the study of wear reduction and in improving machines efficiency and reliability. Finally, it may be concluded that this research, even if in its first phase, shows that graphene is a promising material to be used as lubricant additive. Further experimental investigation will be carried on in order to deeply understand the influence of all parameters that may affect and enhance the tribological performance of GNP compounds. Cheng, Z., Qin, X., 2014. Study on friction performance of graphene-based semi-solid grease. Chinese Chemical Letters 25,1305 – 1307. Curà, F., Mura, A., Adamo, F., 2018. Evaluation of graphene grease compound as lubricant for spline couplings. Tribology International 117, 162 167. ExxonMobil, [Online]. Available: https://www.exxonmobil.com/english-US/Aviation/pds/GLXXMobil-Jet-Oil-II. Fan, X., Wang, L., 2015. High-performance lubricant additives based on modified graphene oxide by ionic liquids. Journal of Colloid and Interface Science 452, 98 – 108. Fuchs,[Online]. Available: https://www.fuchs.com/fileadmin/uk/Media/Brochures/Industrial/FUCHS_RENOLIN_Industrial_Gear_Oils.pdf. Lin, J., Wang L., Chen, G., 2011. Modification of Graphene Platelets and their Tribological Properties as a Lubricant Additive. Tribology Letters 41, 209 – 215. Penkov, O., Kim, H., Kim, H., Kim, D., 2014. Tribology of Graphene: A Review. International Journal of Orecision Engineering and Manufacturing 15, 577-586. Rasheed, A. K., Khalid, M., Rashmi, W., Gupta, T., Chan, A., 2016. Graphene based nanofluids and nanolubricants – Review of recent developments. Renewable and Sustenable Energy Reviews. Senatore, A., D’Agostino, V., Petrone, V., Ciambelli, P., Sarno, M., 2013. Graphene oxide nanosheets as effective friction modifier oil lubricant: materials, methods, and tribological results. ISRN Tribology. Song, H., Li, N., 2011. Frictional behavior of oxide graphene nanosheets as water-base lubricant additive, ApplPhys A 105, 827 – 832. Yang, J., Xia, Y., Song, H., Chen, B., Zhang, Z., 2017. Syntesis of the liquid-like graphene with excellent tribological properties. Tribology International 105, 118-124. Yua, W., Xie, H., Chen, L., Zhu, Z., Zao, J., Zhang, Z., 2014. Graphene based silicone thermal greases. Physics Letters A378, 207 – 211. References