Géraldine Theiler Polymer Composites for Tribological Applications in Hydrogen Environment...
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Transcript of Géraldine Theiler Polymer Composites for Tribological Applications in Hydrogen Environment...
Géraldine Theiler
Polymer Composites for Tribological Applications in Hydrogen Environment
(Bundesanstalt für Materialforschung und -prüfung)Federal Institute for Materials Research and Testing
Berlin, Germany
2nd International Conference on Hydrogen Safety
11-13 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 Experiments Results Conclusion
Tribological Behaviour
Materials
TemperatureEnvironment
Friction heatMaterial properties
Triboreaction
Deformation
Test parameters
Hydrogen Lowv
FN
(1)
(3)(2)
(4)
3
Cryo-, Hydrogen- & Vacuumtribology
Materials
Polymer composites with good tribological performance
Introduction Materials and Experiments Results Conclusion
Polymer Matrix:
PTFE : polytetrafluoroethylenePEEK : polyetheretherketonePI : polyimidePA : PolyamidePEI : polyetherimideEP : epoxy
Fibers: CF : carbon fibers
Fillers:PEEK, PPSbronzeTiO2
Solid lubricants:PTFE, MoS2, graphite200µm
15% PTFE + 15% CF filled PEEK
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Cryo-, Hydrogen- & Vacuumtribology
Materials
Introduction Materials and Experiments Results Conclusion
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
5
Cryo-, Hydrogen- & Vacuumtribology
Tribological Experiments
Pin-on-disc configuration Test parameters
Disc: Steel 52100 Ø 40 mm
Pin: Polymer composite4*4 mm² FN
Friction Pin
Normal load 50 NSliding speed 0.2 m/sSliding distance 2000 m
Wear
Normal load 16 NSliding speed 0.2 m/sSliding distance 2000 m
Experiments- at RT in air, hydrogen and helium gas- LH2 (-253°C)
Introduction Materials and Experiments Results Conclusion
6
Cryo-, Hydrogen- & Vacuumtribology
Cryotribometer
CT2
LH2 ,(LN2 , LHe)
CT3
He, H2 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
0
0,1
0,2
0,3
0,4
0,5
C D E H
fric
tion
coef
ficie
ntAir He H2
8
Cryo-, Hydrogen- & Vacuumtribology
Wear measurements
Smaller wear in liquid hydrogen
0,0
0,5
1,0
1,5
2,0
2,5
3,0
C D H
wea
r ra
te [
mm
³/N
m]
10-6
RT, air LH2 RT, H2
Results Influence of the hydrogen environment
Influence of the composition
9
Cryo-, Hydrogen- & Vacuumtribology
Surface analyses of the disc
Thinner transfer film in LH2 compared to RT in air or H2
LH2RT, H2RT, air
500µm 500µm 500µm
Results Influence of the hydrogen environment
Influence of the composition
10
Cryo-, Hydrogen- & Vacuumtribology
Surface analyses of the polymer pin
RT, H2
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
at RT in air
0
0,1
0,2
0,3
0,4
0,5
0,6
A B C D E F G H I J K L
fric
tio
n c
oef
fici
ent
MoS2 graphite
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
12
Cryo-, Hydrogen- & Vacuumtribology
in liquid hydrogen
0
0,1
0,2
0,3
0,4
0,5
A B C D E F G H I J K L
fric
tio
n c
oef
fici
ent
MoS2 graphite
Friction measurements at RT in air
at RT in air
0
0,1
0,2
0,3
0,4
0,5
0,6
A B C D E F G H I J K L
fric
tio
n c
oef
fici
ent
MoS2 graphite
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. 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 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.
Introduction Materials and Experiments Results Conclusion
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.
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- & VacuumtribologyFriction 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
v v
18
Cryo-, Hydrogen- & Vacuumtribology
Critical heat flux
LN2 LHe