Nanotechnology Now





Heifer International

Wikipedia Affiliate Button


DHgate

Home > Press > University of Pennsylvania Engineers Reveal What Makes Diamonds Slippery at the Nanoscale

Abstract:
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.

University of Pennsylvania Engineers Reveal What Makes Diamonds Slippery at the Nanoscale

Philadelphia, PA | Posted on June 26th, 2008

Robert Carpick, associate professor in the Department of Mechanical Engineering and Applied Mechanics at the University of Pennsylvania, and his group led a collaboration with researchers from Argonne National Laboratories, the University of Wisconsin-Madison and the University of Florida to determine what makes diamond films such slippery customers, settling a debate on the scientific origin of its properties and providing new knowledge that will help create the next generation of super low friction materials.

The Penn experiments, the first study of diamond friction convincingly supported by spectroscopy, looked at two of the main hypotheses posited for years as to why diamonds demonstrate such low friction and wear properties. Using a highly specialized technique know as photoelectron emission microscopy, or PEEM, the study reveals that this slippery behavior comes from passivation of atomic bonds at the diamond surface that were broken during sliding and not from the diamond turning into its more stable form, graphite. The bonds are passivated by dissociative adsorption of water molecules from the surrounding environment. The researchers also found that friction increases dramatically if there is not enough water vapor in the environment.

Some previous explanations for the source of diamond's super low friction and wear assumed that the friction between sliding diamond surfaces imparted energy to the material, converting diamond into graphite, itself a lubricating material. However, until this study no detailed spectroscopic tests had ever been performed to determine the legitimacy of this hypothesis. The PEEM instrument, part of the Advanced Light Source at Lawrence Berkeley National Laboratory, allowed the group to image and identify the chemical changes on the diamond surface that occurred during the sliding experiment.

The team tested a thin film form of diamond known as ultrananocrystalline diamond and found super low friction (a friction coefficient ~0.01, which is more slippery than typical ice) and low wear, even in extremely dry conditions, (relative humidity ~1.0%). Using a microtribometer, a precise friction tester, and X—ray photoelectron emission microscopy, a spatially resolved X-ray spectroscopy technique, they examined wear tracks produced by sliding ultrananocrystalline diamond surfaces together at different relative humidities and loads. They found no detectable formation of graphite and just a small amount of carbon re-bonded from diamond to amorphous carbon. However, oxygen was present on the worn part of the surface, indicating that bonds broken during sliding were eventually passivated by the water molecules in the environment.

Already used in industry as a mechanical seal coating to reduce wear and improve performance and also as a super-hard coating for high-performance cutting tools, this work could help lead to increased use of diamond films in machines and devices to increase service life, prevent wear of parts and save energy wasted by friction.

The study was published in the June issue of the journal Physical Review Letters and was conducted by A.R. Konicek of the Department of Physics and Astronomy at Penn, D.S. Grierson of the Department of Engineering Physics at Wisconsin-Madison, P.U.P.A. Gilbert of the Department of Physics at Wisconsin-Madison, W.G. Sawyer of the Department of Mechanical and Aerospace Engineering at Florida, A.V. Sumant of the Center for Nanoscale Materials at Argonne National Laboratory and Carpick.

Funding was provided by the U.S. Air Force and the U.S. Department of Energy.

####

For more information, please click here

Contacts:
Jordan Reese
215-573-6604

Copyright © University of Pennsylvania

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

Physicists solve quantum tunneling mystery: ANU media release: An international team of scientists studying ultrafast physics have solved a mystery of quantum mechanics, and found that quantum tunneling is an instantaneous process May 27th, 2015

Nanotechnology identifies brain tumor types through MRI 'virtual biopsy' in animal studies: If results are confirmed in humans, tumor cells could someday be diagnosed by MRI imaging and treated with tumor-specific IV injections; new NIH grant will fund future study May 27th, 2015

Who needs water to assemble DNA? Non-aqueous solvent supports DNA nanotechnology May 27th, 2015

Controlled Release of Anticorrosive Materials in Spot by Nanocarriers May 27th, 2015

Govt.-Legislation/Regulation/Funding/Policy

Nanotechnology identifies brain tumor types through MRI 'virtual biopsy' in animal studies: If results are confirmed in humans, tumor cells could someday be diagnosed by MRI imaging and treated with tumor-specific IV injections; new NIH grant will fund future study May 27th, 2015

Who needs water to assemble DNA? Non-aqueous solvent supports DNA nanotechnology May 27th, 2015

One step closer to a single-molecule device: Columbia Engineering researchers first to create a single-molecule diode -- the ultimate in miniaturization for electronic devices -- with potential for real-world applications May 25th, 2015

DNA Double Helix Does Double Duty in Assembling Arrays of Nanoparticles: Synthetic pieces of biological molecule form framework and glue for making nanoparticle clusters and arrays May 25th, 2015

Discoveries

Advance in quantum error correction: Protocol corrects virtually all errors in quantum memory, but requires little measure of quantum states May 27th, 2015

New electronic stent could provide feedback and therapy — then dissolve May 27th, 2015

Seeing the action: UCSB researchers develop a novel device to image the minute forces and actions involved in cell membrane hemifusion May 27th, 2015

Physicists solve quantum tunneling mystery: ANU media release: An international team of scientists studying ultrafast physics have solved a mystery of quantum mechanics, and found that quantum tunneling is an instantaneous process May 27th, 2015

Materials/Metamaterials

Controlled Release of Anticorrosive Materials in Spot by Nanocarriers May 27th, 2015

Production of Copper Cobaltite Nanocomposites with Photocatalytic Properties in Iran May 27th, 2015

Dr.Theivasanthi Slashes the Price of Graphene Heavily: World first & lowest price – Nano-price (30 USD / kg) of graphene by nanotechnologist May 26th, 2015

DNA Double Helix Does Double Duty in Assembling Arrays of Nanoparticles: Synthetic pieces of biological molecule form framework and glue for making nanoparticle clusters and arrays May 25th, 2015

Announcements

Physicists solve quantum tunneling mystery: ANU media release: An international team of scientists studying ultrafast physics have solved a mystery of quantum mechanics, and found that quantum tunneling is an instantaneous process May 27th, 2015

Nanotechnology identifies brain tumor types through MRI 'virtual biopsy' in animal studies: If results are confirmed in humans, tumor cells could someday be diagnosed by MRI imaging and treated with tumor-specific IV injections; new NIH grant will fund future study May 27th, 2015

Who needs water to assemble DNA? Non-aqueous solvent supports DNA nanotechnology May 27th, 2015

Controlled Release of Anticorrosive Materials in Spot by Nanocarriers May 27th, 2015

Research partnerships

Supercomputer unlocks secrets of plant cells to pave the way for more resilient crops: IBM partners with University of Melbourne and UQ May 21st, 2015

Taking control of light emission: Researchers find a way of tuning light waves by pairing 2 exotic 2-D materials May 20th, 2015

Efficiency record for black silicon solar cells jumps to 22.1 percent: Aalto University's researchers improved their previous record by over 3 absolute percents in cooperation with Universitat Politècnica de Catalunya May 18th, 2015

Organic nanoparticles, more lethal to tumors: Carbon-based nanoparticles could be used to sensitize cancerous tumors to proton radiotherapy and induce more focused destruction of cancer cells, a new study shows May 18th, 2015

NanoNews-Digest
The latest news from around the world, FREE




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More










ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project