Shivalik:
We have been working on silicon and related materials concerning friction
and adhesion for a couple of years. Since there was no commercial friction
tester available, we built one (see bottom for URL).
I assume that you are dealing with forces in the micro newton range.
If this is so you have to expect electrostatic forces and after proper
grounding stong capillary forces.
It is therefore hard to say, which value friction has. We measured the
friction force in air as well as in UHV and learned that the value drops
as the pressure in the chamber decreases. This is caused by the desorption
of water.
Less water results in lower capillary forces. If the water has a thickness of
just a couple of monolayers ordering phenomena set in, resulting in strong
stick slips.
As usual in tribology, it is too hard to forecast what friction will be like.
Thus, it is always necessary to measure.

Best Regards,
Matt


Dr. Matthias Scherge
Microtribology Group
Technische Universitaet Ilmenau
PF 100565
D-98684 Ilmenau
Tel +49 3677 3782
Fax +49 3677 3771
ttp://imath.mathematik.tu-ilmenau.de/phys/personal/tribo.html