Formulation and Characterization of PAI-PTFE-cg Antifriction Coatings

Abstract:

Polytetrafluoroethylene (PTFE) powder is used as a solid lubricant in commercial antifriction coatings. However, most of the matrix polymers are usually not compatible with virgin PTFE resulting in low dispersion and mechanical film stability and adhesion. In our research PTFE TF 2025 was irradiated by g-beam generating PTFE micropowder with persistant radicals and functional groups. These functional groups are able to perform a chemical grafting (cg) of polyamideimide (PAI) and modified PTFE-micropowder by reactive extrusion in melt. Based on grinded extrudates PAI-PTFE-cg dispersions were formulated followed by characterizing dispersion as well as film properties. It was found, that PAI-PTFE-cg dispersion comprises very small PTFE-particles at higher g-irradiation doses in homogeneous dispersions. In addition, all samples showed outstanding film flexibility. Basic tribological properties under mixed lubrication were studied by using a ring-on-disk tribometer. Finally, diluted dispersions were applied to a multi-surface sliding bearing (four segments) for testing in a hydrodynamic plain test bench.

• Periodical: Key Engineering Materials (Volume 721)
• Pages: 362-367
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.721.362
• Online since: December 2016
• Authors: Michaela Gedan-Smolka*, Anne Marschner, Dieter Lehmann, Rainer Franke, Marco Klemm, Erhard Leidich, Björn Prase
• Keywords: PAI, PAI-PTFE-cg Dispersion, PTFE, Solid Lubricant

References

[1] K. Lunkwitz, U. Lappan, U. Scheler, Modification of perfluorinated polymers by high-energy irradiation, Journal of Fluorine Chemistry 125 (2004) 863-873.

DOI: 10.1016/j.jfluchem.2004.01.020

[2] T. Hoffmann, M. Heller, D. Jehnichen, T. Engelhardt, D. Lehmann, Influence of Absorbing Materials on the Funtionalization of Poly(tetrafluoroethylene) During g-Irradiation, J. of Applied Polymer Science 130 (2013) 1787-1793.

DOI: 10.1002/app.39346

[3] A. Taeger, T. Hoffmann, W. Butwilowski, M. Heller, T. Engelhardt and D. Lehmann, Evidence of chemical compatibilization reaction between poly(ether ether ketone) and irradiation- modified poly (tetrafluoroethylene), High Performance Polymers 26 (2014).

DOI: 10.1177/0954008313506724

[4] A. Frick, D. Sich, G. Heinrich, D. Lehmann, U. Gohs, C. Stern, Properties of Melt Processable PTFE/PEEK Blends: the Effect of Reactive Compatibilization Using Electron Beam Irradiated Melt Processable PTFE, J. Appl. Polym. Sci. 128 (2013).

DOI: 10.1002/app.38337

[5] M. Gedan-Smolka, D. Lehmann, A. Marschner, K. Kunze, R. Franke, I. Haase, Chemisch kompatibilisierte PAI-PTFE-cg-Gleitlacke, 52. Tribologie-Fachtagung Göttingen, Proceedings volume I (2011) No. 21, ISBN 978-3-00-035439-7.

DOI: 10.4028/www.scientific.net/kem.721.362

[6] R. Franke, D. Lehmann & K. Kunze, Tribological behaviour of new chemically bonded PTFE polyamide compounds. Wear, 262, 3-4 (2007) 242-252.

DOI: 10.1016/j.wear.2006.05.001

[7] E. Leidich, B. Prase, Characteristics of hydrodynamic plain bearings with bonded coating, The 17th Nordic Symposium on Tribology - NORDTRIB 2016, June 14-17, Aulanko, Hämeenlinna, Finland (2016) 219.

[8] T. Hoffmann, M. Heller, T. Engelhardt, A. Taeger, H. Marks, D. Lehmann, Strahlenchemisches Recycling von PTFE-Materialien, GAK: Gummi Fasern Kunststoffe 65 (2012) 784-789.