Géraldine Theiler Polymer Composites for Tribological Applications in Hydrogen Environment (Bundesanstalt für Materialforschung und -prüfung) Federal Institute for Materials Research and Testing Berlin, Germany 2 nd International Conference on Hydrogen Safety September 2007, San Sebastián, Spain

2 Cryo-, Hydrogen- & Vacuumtribology Applications –Storage and distribution of hydrogen Components –Bearings, seals, valves, pumps Tribosystems in hydrogen Introduction Materials and ExperimentsResults Conclusion Tribological Behaviour Materials Temperature Environment Friction heat Material properties Triboreaction Deformation Test parameters Hydrogen Low v FNFN (1) (3) (2) (4)

3 Cryo-, Hydrogen- & Vacuumtribology Materials Polymer composites with good tribological performance Introduction Materials and Experiments Results Conclusion Polymer Matrix: PTFE : polytetrafluoroethylene PEEK : polyetheretherketone PI : polyimide PA : Polyamide PEI : polyetherimide EP : epoxy Fibers: CF : carbon fibers Fillers: PEEK, PPS bronze TiO 2 Solid lubricants: PTFE, MoS 2, graphite 200µm 15% PTFE + 15% CF filled PEEK

4 Cryo-, Hydrogen- & Vacuumtribology Materials Introduction Materials and Experiments Results Conclusion NameMatrixFibersFillersLubricants APEEK10% CF10% PTFE + 10% MoS 2 BPI15% MoS 2 CPEEK13% CF10% PTFE DPTFE18,2% CF13,5% PEEK EPTFE16,7% CF9,2% bronze FPTFE20% PPS GPA30% PTFE HPEEK10% CF10% PTFE + 10% graphite IPEEK15% CF5% PTFE + 5% graphite JEP15% CF5% TiO 2 15% graphite KPEI5% CF5% TiO 2 15% graphite LPA15% CF5% TiO 2 5% graphite

5 Cryo-, Hydrogen- & Vacuumtribology Tribological Experiments Pin-on-disc configurationTest parameters Disc: Steel Ø 40 mm Pin: Polymer composite 4*4 mm² FNFN Friction Pin Normal load50 N Sliding speed0.2 m/s Sliding distance2000 m Wear Normal load16 N Sliding speed0.2 m/s Sliding distance2000 m Experiments - at RT in air, hydrogen and helium gas - LH 2 (-253°C) Introduction Materials and Experiments Results Conclusion

6 Cryo-, Hydrogen- & Vacuumtribology Cryotribometer CT2 LH 2,(LN 2, LHe) CT3 He, H 2 Gas Introduction Materials and Experiments Results Conclusion

7 Cryo-, Hydrogen- & Vacuumtribology Friction measurements at RT Results Influence of the hydrogen environment  Lower friction in hydrogen Influence of the composition

8 Cryo-, Hydrogen- & Vacuumtribology Wear measurements  Smaller wear in liquid hydrogen Results Influence of the hydrogen environment Influence of the composition

9 Cryo-, Hydrogen- & Vacuumtribology Surface analyses of the disc  Thinner transfer film in LH 2 compared to RT in air or H 2 LH 2 RT, H 2 RT, air 500µm Results Influence of the hydrogen environment Influence of the composition

10 Cryo-, Hydrogen- & Vacuumtribology Surface analyses of the polymer pin RT, H 2 RT, air  More iron on the surface of the polymer after test in air EDX analyses of the polymer pins Results Influence of the hydrogen environment Influence of the composition Fe F

11 Cryo-, Hydrogen- & Vacuumtribology Friction measurements at RT in air Results Influence of the hydrogen environment Influence of the composition NameMatrix APEEK BPI CPEEK DPTFE E F GPA HPEEK I JEP KPEI LPA

12 Cryo-, Hydrogen- & Vacuumtribology Friction measurements at RT in air Results Influence of the hydrogen environment Influence of the composition

13 Cryo-, Hydrogen- & Vacuumtribology Conclusions and recommendations Hydrogen has a beneficial effect on the friction behaviour of polymer composites. H 2 seems to prevent the iron from transferring onto the pin. Polymer transfer onto the counterpart (steel disc) is lower in hydrogen environment. In LH 2, the wear rate is lower than at RT in hydrogen. The polymer matrix doesn‘t have a significant influence on the friction performance of the composite in hydrogen. However, the choice of the solid lubricant is more important. IntroductionMaterials and ExperimentsResults Conclusion  From a tribological point of view, polymer composites are suitable and reliable in (liquid) hydrogen environment.  It is recommended to avoid MoS 2 and to use graphite containing materials which give the best performance.

14 Cryo-, Hydrogen- & Vacuumtribology Thanks to BAM VI.2, BAM VI.4, Berlin IVW GmbH, Kaiserslautern German Research Association (DFG) (Hu 791/2-1) Thank you for your attention

15 Cryo-, Hydrogen- & Vacuumtribology

16 Cryo-, Hydrogen- & Vacuumtribology Experiments: Environments

17 Cryo-, Hydrogen- & Vacuumtribology Friction power at low temperature Low friction Bubles at the friction contact optimal cooling effect, small ΔT Q Q High friction Gas film at the friction contact max. Temperature over RT vv

18 Cryo-, Hydrogen- & Vacuumtribology Critical heat flux LN 2 LHe