Tribology of Ge thin films on stainless steel
Abstract
Purpose
The purpose of this paper is to study the friction and wear behavior of germanium (Ge) thin films deposited by low-pressure chemical vapor deposition method on a chromium (Cr)-nickel (Ni) stainless steel substrate after being exposed to relatively mild sliding conditions (low loads and sliding distances).
Design/methodology/approach
Wear and friction experiments were conducted with a 100Cr6 steel ball sliding against flat Ge thin-film-coated stainless steel sheets (ball-on-flat microtribometer, no lubricant, normal loads of 50-100 mN, initial Hertzian contact pressures of 385-485 MPa, total sliding distance up to 200 mm and room temperature).
Findings
Scanning electron microscopy results revealed that prepared Ge thin films consisted of two different morphologies: curved nanowires and cone-shaped nano-/microdroplets. Regarding friction and wear characteristics of the investigated samples, the substrates coated with Ge thin films did not affect the coefficient of friction significantly by load. The wear of the base material (Cr-Ni stainless steel) was not observed under the mentioned experimental conditions (see the “Design/methodology/approach” section); however, with increased sliding distance and/or applied load, a rupture of the Ge film and an exposure of the stainless steel substrate to the 100Cr6 ball can be expected. Furthermore, the observations suggest that the smearing of Ge nano- and microstructures, plastically deformed during tribotesting, over the surface exposed to the sliding contact is the dominant tribological process.
Originality/value
For the first time, the tribological interaction between Ge thin film and steel surface was investigated under dry sliding conditions using a ball-on-flat microtribometer, and the obtained results provide a useful base for the further research on tribology of Ge-based thin films.
Keywords
Acknowledgements
This work was funded by the “Austrian COMET-Program” (project XTribology, no. 849109) via the Austrian Research Promotion Agency (FFG) and the Province of Niederösterreich, Vorarlberg and Wien. This work was also supported by the Grant Agency of the Czech Republic (GACR) under project No. 15-08842J. The work has been carried out within the “Excellence Centre of Tribology” (AC2T research GmbH) and the Institute of Chemical Process Fundamentals of the CAS, v. v. i.
Citation
Krabac, L., Pejaković, V., Drinek, V., Dörr, N. and Badisch, E. (2017), "Tribology of Ge thin films on stainless steel", Industrial Lubrication and Tribology, Vol. 69 No. 2, pp. 182-189. https://doi.org/10.1108/ILT-06-2016-0128
Publisher
:Emerald Publishing Limited
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