Influence of Transfer Film Formation Mechanisms on the Friction and Wear of Polymer Matrix Composites
Final Report Abstract
The main objective of this project was to improve the understanding of transfer films and the correlation between transfer film formation, transfer film thickness and the tribological performance of the respective material combination. In order to achieve that, the novel method of transfer film lumimance analysis (TLA) was used and optimized and applied to a range of carefully designed and manufactured materials. Our main findings were that there is a significant in-situ correlation between the coefficient of friction and the change of relative luminance, i.e. transfer film formation. While some fillers, like graphite, silica or PTFE form stable transfer films in PPS and EP, other fillers, especially carbon fibers, are disruptive to the transfer film formation process. We were able to demonstrate that combining carbon fibers with other fillers reduced the fibers’ disruptive action to varying degrees, with silica working best. On the other hand, we found no significant impact of silica size (50 nm, 250 nm, 600 nm) or shape on friction, wear or transfer film formation. As we investigated a total of three different representative matrix materials (EP, PA6, PPS), we were furthermore able to demonstrate that fillers do not necessarily exhibit similar behavior in terms of transfer film formation and stability in those matrices, as can be seen from the perfectly stable transfer film formed by carbon fiber filled PA6, in contrast to the high instabilities that carbon fibers cause in PPS and EP. Therefore, transfer film formation and stability seem to dependent significantly on the respective matrix material. In addition to the insights that we have gained from applying TLA to a wide range of materials, we also made great progress in terms of experimental techniques: TLA was developed from a basic concept into a fully working method and we demonstrated how chemical dissolution of transfer films can eliminate the potentially misleading assumption of an unmodified baseline in profilometric film height measurement. The TLA method has been patented. Parallel to our experimental studies, modelling approaches were conducted by our Russian partner at Tomsk. The results were in good match to our test results and are already published.
Publications
- Neues Verfahren zur quantitativen in situ-Erfassung von Transferfilmen in Kunststoff-Metall-Gleitkontakten, 59. Tribologie-Fachtagung 2018, 24-26.09.2018, Göttingen, Germany
A. Gebhard, B.C. Jim, B. Wetzel
- Influence of the Filler Size and the Counter body Surface on the Formation of a Friction Layer Under Solid Lubricated Polymer Nanocomposite S- Steel Sliding, Russian Physics Journal 62 (2019) 1409
A. I. Dmitriev, B. C. Jim
(See online at https://doi.org/10.1007/s11182-019-01858-x) - Novel In-situ Method for Studying Transfer Films and Tribology Performance of Additives, Automotive Composites Conference & Exhibition (ACCE), 04-06.09.2019, Novi, Michigan, USA
B.C. Jim, R.J. Robin
- On the kinetic and stability of transfer films in polymer/ metal slide pairings, 60. Tribologie-Fachtagung 2019, 23-25.09.2019, Göttingen, Germany
B.C. Jim, A. Gebhard, B. Wetzel
- Study of the influence of size and shape of nanofillers of a polymer composite on the tribolayer formation, 10th International Conference BALTTRIB 2019, 14-16.11. 2019, Kaunas, Lithunia
A.I. Dmitriev, B.C. Jim, B. Wetzel
(See online at https://doi.org/10.15544/balttrib.2019.04) - Verfahren und Vorrichtung zur zeitaufgelösten Analyse von Transferfilmen, Institut für Verbundwerkstoffe GmbH, 2019, DE 10 2018 110 692
A. Gebhard, B.C. Jim
- Photo-optical luminance analysis of transfer films: Measurement principle, data analysis and result plotting. Tribology International 153 (2021)
A. Gebhard, B.C. Jim
(See online at https://doi.org/10.1016/j.triboint.2020.106626)
