Mechanical tests were performed to study the potential utility of nanoparticle liquids as electrically conductive lubricants in relay switches in micro-electromechanical systems. For these tests, the nanoparticle liquids were spin-coated to an average thickness of 2 to 3 nm (amounting to sub-monolayer coverage) on gold substrates. In the test of each such coated substrate, a ball was pressed onto the substrate with a controllable, reproducible force, and the resulting contact resistance was measured as the ball was slid across the surface in a cyclic motion at a frequency of 5 Hz. For comparison, the same tests were performed on uncoated gold substrates. The results of these tests were interpreted as demonstrating that the gold-nanoparticle coatings increased the durabilities (quantified in terms of numbers of cycles until failure) by factors ranging from about 10 to about 10³.

It is speculated that a nanoparticle-liquid coat of the type tested can reconfigure itself through fluid-like motion and thereby can heal itself when it is damaged by rubbing in use as an electrically conductive lubricant. More specifically, it is speculated that as such a lubricant in a relay-switch contact becomes worn out through mechanical deformation of the nanoparticles and ashing of the carbonaceous coats on the nanoparticles, the undamaged portions of the lubricant can flow into the damaged areas and thereby heal the coat.

This work was done by Robert I. MacCuspie, Andrea M. Elsen, Steve Patton, J. David Jacobs, Steve Diamanti, Michael Arlen, Andrey A. Voevodin, and Richard A. Vaia of the Air Force Research Laboratory.
AFRL-0054

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