Polymer Composites for Tribological Applications in Hydrogen Environment

1
Polymer Composites for Tribological Applications
in Hydrogen Environment

• (Bundesanstalt für Materialforschung und
  -prüfung)Federal Institute for Materials
  Research and TestingBerlin, Germany
• 2nd International Conference on Hydrogen Safety
• 11-13 September 2007, San Sebastián, Spain

2
Tribosystems in hydrogen

• Applications
• Storage and distribution of hydrogen
• Components
• Bearings, seals, valves, pumps

Deformation
Materials
Test parameters
Tribological Behaviour
FN
(4)
(1)
Material properties
Friction heat
(3)
Temperature
Environment
Low
Hydrogen
(2)
v
Triboreaction
Introduction
Materials and Experiments
Results
Conclusion
3
Materials

• Polymer composites with good tribological
  performance

Polymer Matrix PTFE polytetrafluoroethylene PE
EK polyetheretherketone PI polyimide PA
Polyamide PEI polyetherimide EP
epoxy Fibers CF carbon
fibers Fillers PEEK, PPS bronze TiO2 Solid
lubricants PTFE, MoS2, graphite
200µm
15 PTFE 15 CF filled PEEK
Introduction
Materials and Experiments
Results
Conclusion
4
Materials
Name Matrix Fibers Fillers Lubricants
A PEEK 10 CF 10 PTFE 10 MoS2
B PI 15 MoS2
C PEEK 13 CF 10 PTFE
D PTFE 18,2 CF 13,5 PEEK
E PTFE 16,7 CF 9,2 bronze
F PTFE 20 PPS
G PA 30 PTFE
H PEEK 10 CF 10 PTFE 10 graphite
I PEEK 15 CF 5 PTFE 5 graphite
J EP 15 CF 5 TiO2 15 graphite
K PEI 5 CF 5 TiO2 15 graphite
L PA 15 CF 5 TiO2 5 graphite
Introduction
Materials and Experiments
Results
Conclusion
5
Tribological Experiments

• Pin-on-disc configuration

Test parameters
Friction Pin Normal load 50
N Sliding speed 0.2 m/s Sliding distance 2000
m Wear Normal load 16 N Sliding speed 0.2
m/s Sliding distance 2000 m
Disc Steel 52100 Ø 40 mm
Pin Polymer composite 44 mm²
FN

• Experiments
• at RT in air, hydrogen and helium gas
• LH2 (-253C)

Introduction
Materials and Experiments
Results
Conclusion
6
Cryotribometer
CT2 LH2 ,(LN2 , LHe)
CT3 He, H2 Gas
Introduction
Materials and Experiments
Results
Conclusion
7
Friction measurements at RT

• Lower friction in hydrogen

Influence of the hydrogen environment

Influence of the composition

Results
8
Wear measurements

• Smaller wear in liquid hydrogen

Influence of the hydrogen environment

Influence of the composition

Results
9
Surface analyses of the disc
LH2
RT, H2
RT, air
500µm
500µm
500µm

• Thinner transfer film in LH2 compared to RT in
  air or H2

Influence of the hydrogen environment

Influence of the composition

Results
10
Surface analyses of the polymer pin
RT, H2
RT, air
Fe
F
EDX analyses of the polymer pins

• More iron on the surface of the polymer after
  test in air

Influence of the hydrogen environment

Influence of the composition

Results
11
Friction measurements at RT in air
Name Matrix
A PEEK
B PI
C PEEK
D PTFE
E PTFE
F PTFE
G PA
H PEEK
I PEEK
J EP
K PEI
L PA
Influence of the hydrogen environment

Influence of the composition

Results
12
Friction measurements at RT in air
Influence of the hydrogen environment

Influence of the composition

Results
13
Conclusions and recommendations

• Hydrogen has a beneficial effect on the friction
  behaviour of polymer composites. H2 seems to
  prevent the iron from transferring onto the pin.
• Polymer transfer onto the counterpart (steel
  disc) is lower in hydrogen environment.
• In LH2, the wear rate is lower than at RT in
  hydrogen.
• The polymer matrix doesnt have a significant
  influence on the friction performance of the
  composite in hydrogen. However, the choice of the
  solid lubricant is more important.

• From a tribological point of view, polymer
  composites are suitable and reliable in (liquid)
  hydrogen environment.
• It is recommended to avoid MoS2 and to use
  graphite containing materials which give the best
  performance.

Conclusion
Introduction
Materials and Experiments
Results
14
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
(No Transcript)
16
Experiments Environments
17
Friction power at low temperature

• Low friction
• Bubles at the friction contact
• optimal cooling effect, small ?T

High friction Gas film at the friction
contact max. Temperature over RT
Q
Q
v
v
18
Critical heat flux
LN2
LHe