Faculty of Science and Technology
Chair of Surface and Materials Technology
Institute of Materials Engineering
Rolling, Sliding and Torsion friction of
single silica microspheres:
Comparison of nanoindentation based
experimental data with DEM simulation
Part A
Regina Fuchs, Jan Meyer, Thorsten Staedler and Xin Jiang (University of Siegen, Germany)
Thomas Weinhart, Vanessa Magnanimo, Stefan Luding (University of Twente, Netherlands)
AdityaSiegen,
Kumar - 1University
ofof
Siegen
st and 2nd
Workshop “Dialogue: Experiment-Model“, Universität
October 2012
Particle/surface interaction – Starting Point
Is it possible to measure rolling of
single silica microspheres on surfaces
with a commercial nanoindenter setup?
Regina Fuchs - University of Siegen
Particle/surface interaction – Proof of principle
Proof of principle:
• Pure sliding experiments
• Borsilica spheres with diameter of 20µm
• Indenter: Diamond flat end (diameter 20µm), Colloid probe (diameter 20µm)
Contact pair: glass and diamond
Regina Fuchs - University of Siegen
Particle/surface interaction – Proof of principle
0,9
A
B
0,8
friction coefficient
0,7
0,6
0,5
0,4
0,3
0,2
0,1
0
2
20
200
2000
F(N) / µN
Regina Fuchs - University of Siegen
Particle/surface interaction – Proof of principle
What happens in case of a free sphere?
Contact: diamond – glass – diamond
Regina Fuchs - University of Siegen
Particle/surface interaction – Proof of principle
1
A
B
C
0,9
friction coefficient
0,8
0,7
0,6
0,5
0,4
0,3
0,2
0,1
0
2
20
200
2000
F(N)/ µN
Regina Fuchs - University of Siegen
Particle/surface interaction – Proof of principle
0,6
Combination of
different motion
friction coefficient
0,5
0,4
0,3
0,2
Rolling
0,1
0
2
20
200
2000
F(N)/ µN
Regina Fuchs - University of Siegen
Particle/surface interaction – Proof of principle
Conclusion:
•
Sliding experiment:
 Same friction coefficient for case A (colloid over diamond) and B (diamond over
fixed sphere)
•
Rolling experiment:
 Clear difference compared to sliding experiments
 Friction coefficient (after critical load) one order of magnitude smaller than
sliding friction coefficient
 Lateral forces much smaller than in sliding experiment
 Critical torsional moment necessary for rolling  critical Load exist  Well
known in Literature1;2
Our assumption: Rolling friction for F(N) > 100µN
1. Shigeki Saito, Hideki T. Miyazaki, Tomomasa Sato, and Kunio Takahashi, J Appl Phys 92 (9), 5140 (2002)
2. M. D. M. Peri and C. Cetinkaya, Philosophical Magazine 85 (13), 1347 (2005)
Regina Fuchs - University of Siegen
Particle/surface interaction – Friction loop
Rolling friction coefficient ~ 0.002
Friction loops are
utilized
Need for best possible measurement strategies
•
•
Friction Loop
•
•
F(L)/µN
Δ=
𝑀𝑏 + 𝑀𝑓
2
Advantages:
Mb
W
0
40%RH, RT
2 µm lateral
displacement
1 µm/s scan speed
Various normal
loads
Δ
Mf
W = half-width of the loop
Δ = offset of the loop
Mb= Lateral force backward
Mf = lateral force forward
Lateral displacement /µm
- Compensation of
Instrument Artifact
- Compensation of
System Artifact
- Reduce Error
- Comparable to AFM
measurements
Regina Fuchs - University of Siegen
Particle/surface interaction – Result (1)
Quartz
5
Silicon
F(L) / µN
4
3
2
•
Quartz and Silicon
similar lateral forces
1
•
Linear relationship
F(L) vs. F(N)
0
0
500
1000
1500
2000
2500
3000
F(N) /µN
Regina Fuchs - University of Siegen
Particle/surface interaction – Result (2)
18
20µm sphere
16
5µm sphere
14
F(L) /µN
12
10
•
Small F(N): F(L) for 5µm and
20µm spheres similar
8
•
F(N) higher: plastic deformation in
case of 5µm sphere  has to be
proven by experiments
6
4
2
0
0
500
1000
1500
2000
2500
3000
F(N) /µN
Regina Fuchs - University of Siegen
Particle/surface interaction – Rail system
Movement of Sphere (15µm scratch) sometimes differs from scratch axis!
correlation between rolling and torsion?
Is distinction between rolling and torsion friction coefficient possible?
25°
Torsion
Rolling
45°
Reducing degrees of freedom
65°
Angle between rail-slopes will determine composition of friction
Regina Fuchs - University of Siegen
Particle/surface interaction – Rail system
Rail System:
•
Reducing degree of freedom
•
Produced by FIB
•
Rail material: Silicon
•
Different angle of the rail θ = 0°, 25°, 45° (later up to 85°)
•
Focal point of sphere shifted to 60% (inside rail)
•
Comparison of nanoindentation based experimental data
with the Discrete Element Method (DEM) simulation
Regina Fuchs - University of Siegen
Particle/surface interaction – Results Rail system
30
0°
25
25°
F(L) /µN
20
45°
15
Increasing lateral force with
angle of rail system!
10
More…
PART B
5
0
0
500
1000
1500
2000
2500
3000
F(N)/ µN
Regina Fuchs - University of Siegen
Particle/surface interaction – Conclusion
•
Proof of principle:
 Clear difference between friction coefficient of pure sliding and rolling
 Commercial nanoindenter setup useful to measure rolling and sliding friction
•
Friction loop:
 Best possible resolution  reduced Error
 Compensation of Artifact
•
Substrate:
 Similar surfaces show similar F(L) vs. F(N) behavior
 F(L) vs. F(N) linear relationship
•
Radius of Spheres:
 5µm spheres show at higher load a non-linear F(L) vs. F(N) behavior
 Understanding of plastic deformation possible
•
Rail system:
 Correlation between rolling and torsion
Regina Fuchs - University of Siegen
Particle/surface interaction – Outlook
Comparison with DEM Simulation!!!
More…
Rolling, Sliding and Torsion friction of single silica
microspheres:
Comparison of nanoindentation based
experimental data with DEM simulation
Part B
Regina Fuchs - University of Siegen
Thank you
for your
attention!
Regina Fuchs - University of Siegen