Lateral vibrations can control friction at the nanoscale, researchers reported in the 1 July 2005 issue of Physical Review Letters.
The researchers modeled a tip interacting with a substrate that vibrates in the lateral direction, and showed that vibrations at the correct frequency and amplitude can dramatically reduce friction, and can even make it possible to transform stick-slip motion to smooth sliding.
Previous studies have suggested controlling friction with normal vibrations; this paper adds another new method scientists can potentially use to reduce friction. The authors also suggest experiments to test the effects they predict.
Being able to control friction in this way may be useful for micromechanical devices and computer disk drives, where friction may cause unwanted stick-slip motion or damage to the device.
Publication:
Z. Tshiprut, A. E. Filippov, and M. Urbakh
Phys. Rev. Lett.
95, 016101 (2005)
http://link.aps.org/abstract/PRL/v95/e016101
Abstract
Tuning Diffusion and Friction in Microscopic Contacts By Mechanical Excitations
We demonstrate that lateral vibrations of a substrate can dramatically increase surface diffusivity and mobility and reduce friction at the nanoscale. Dilatancy is shown to play an essential role in the dynamics of a nanometer-size tip which interacts with a vibrating surface. We find an abrupt dilatancy transition from the state with a small tip-surface separation to the state with a large separation as the vibration frequency increases. Atomic force microscopy experiments are suggested which can test the predicted effects.
Related stories:
'Heftier' atoms reduce friction at the nanoscale
A research team led by a University of Pennsylvania mechanical engineer has discovered that friction between two sliding bodies can be reduced at the molecular, or nanoscale, level by changing the mass of the atoms at the surface. “Heavier” atoms vibrate at a lower frequency, reducing energy lost during sliding.
Ultrananocrystalline-diamond coating improves mechanical pump seals
(PhysOrg.com) -- From petroleum to food and beverage to pharmaceuticals, most industries use mechanical pumps, and all these pumps rely on seals to reduce leaks and maintenance costs. Argonne researchers, along with industry partners, have developed a new, efficient and cost-effective alternative to conventional seals.
Micro honeycomb materials enable new physics in aircraft sound reduction
Noise from commercial and military jet aircraft causes environmental problems for communities near airports, obliging airplanes to follow often complex noise-abatement procedures on takeoff and landing. It can also make aircraft interiors excessively loud.
Fuel-saving designs improve efficiency of hydraulic systems
Researchers at Purdue University have shown how to reduce fuel consumption and dramatically improve the efficiency of hydraulic pumps and motors in heavy construction equipment.
Slippery Customer: A Greener Antiwear Additive for Engine Oils
(PhysOrg.com) -- Titanium, a protean element with applications from pigments to aerospace alloys, could get a new role as an environmentally friendly additive for automotive oil, thanks to work by materials scientists from Afton Chemical Corporation (Richmond, Va.) and the National Institute of Standards and Technology.
Self-moisturizing contact lenses, naturally
Even contact lenses are joining the trend to go green. Chemical engineering researchers at McMaster University have shown that a common fluid found in our bodies can be used as a natural moisturizing agent in contact lenses.
University of Pennsylvania engineers reveal what makes diamonds slippery at the nanoscale
They call diamonds "ice," and not just because they sparkle. Engineers and physicists have long studied diamond because even though the material is as hard as an ice ball to the head, diamond slips and slides with remarkably low friction, making it an ideal material or coating for seals, high performance tools and high-tech moving parts.
Lakes of meltwater can crack Greenland's ice and contribute to faster ice sheet flow
Researchers from the Woods Hole Oceanographic Institution (WHOI) and the University of Washington (UW) have for the first time documented the sudden and complete drainage of a lake of meltwater from the top of the Greenland ice sheet to its base. From those observations, scientists have uncovered a plumbing system for the ice sheet, where meltwater can penetrate thick, cold ice and accelerate some of the large-scale summer movements of the ice sheet.