Influence of Surface Design on the Solid Lubricity of Carbon Nanotubes-Coated Steel Surfaces
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Topographically designed surfaces are able to store solid lubricants, preventing their removal out of the tribological contact and thus significantly prolonging the lubrication lifetime of a surface. The present study provides a systematic evaluation of the influence of surface structure design on the solid lubrication effect of multi-walled carbon nanotubes (MWCNT) coated steel surfaces. For this purpose, direct laser writing using a femtosecond pulsed laser system is deployed to create surface structures, which are subsequently coated with MWCNT by electrophoretic deposition. The structural depth or aspect ratio of the structures and thus the lubricant storage volume of the solid lubricant is varied. The frictional behavior of the surfaces is recorded using a ball-on-disk tribometer and the surfaces are thoroughly characterized by complementary characterization techniques. Efficient lubrication is achieved for all MWCNT-coated surfaces. However, and in contrast to what would be expected, it is shown that deeper structures with larger lubricant storage volume do not lead to an extended lubrication lifetime and behave almost equally to the coated unstructured surfaces. This can be attributed, among other things, to differences in the final surface roughness of the structures and the slope steepness of the structures, which prevent efficient lubricant supply into the contact.
KeywordsSolid lubrication Laser structuring Carbon nanotubes Coatings Surface modification
The present work is supported by funding from the Deutsche Forschungsgemeinschaft (DFG, project: MU 959/38-1 and SU 911/1-1). The authors wish to acknowledge the EFRE Funds of the European Commission for support of activities within the AME-Lab project. This work was supported by the CREATe-Network Project, Horizon 2020 of the European Commission (RISE Project No. 644013). We thank Prof. Volker Presser (INM, Saarbrücken) for providing access to the Raman spectrometer and SFB 926 "Microscale Morphology of Component Surfaces" CRC 926 for measurements by Auger electron spectroscopy.
- 4.Szurdak, A., Rosenkranz, A., Gachot, C., Hirt, G., Mücklich, F.: Manufacturing and tribological investigation of hot micro-coined lubrication pockets. Key Eng. Mater. 611–612, 417–424 (2014). https://doi.org/10.4028/www.scientific.net/KEM.611-612.417 CrossRefGoogle Scholar
- 9.Mücklich, F., Lasagni, A., Daniel, C.: Laser Interference Metallurgy – using interference as a tool for micro/nano structuring. Zeitschrift. Für. Met. 97, 1337–1344 (2006)Google Scholar
- 43.Sarkar, P., Nicholson, P.S.: Electrophoretic deposition (EPD): Mechanisms, kinetics, and application to ceramics. J. Am. Ceram. Soc. 79, 1987–2002 (1996). https://doi.org/10.1111/j.1151-2916.1996.tb08929.x CrossRefGoogle Scholar
- 46.Lasagni, A.: Advanced design of periodical structures by laser interference metallurgy in the micro / nano scale on macroscopic areas. Saarland University, Saarbrücken (2006)Google Scholar
- 50.Thomas, B.J.C., Shaffer, M.S.P., Freeman, S., Koopman, M., Chawla, K.K., Boccaccini, A.R.: Electrophoretic Deposition of Carbon Nanotubes on Metallic Surfaces. Key Eng. Mater. 314, 141–146 (2006). https://doi.org/10.4028/www.scientific.net/KEM.314.141 CrossRefGoogle Scholar
- 56.DiLeo, R.A., Landi, B.J., Raffaelle, R.P.: Purity assessment of multiwalled carbon nanotubes by Raman spectroscopy. J. Appl. Phys. 2007;101. https://doi.org/10.1063/1.2712152