Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Diamonds in the crush

14.08.2014

Theoretical simulations reveal how nanoscale lubricating systems can ease friction between surfaces cMain Contentoated with diamond-like carbon

Diamond-like-carbon (DLC) coatings are an innovative technology, exhibiting the twin properties of mechanical toughness and ultralow friction. These features, which are desirable in abrasive environments, have led to the widespread adoption of DLC films in microelectromechanical systems, such as hard disk drives.


Device longevity can be improved through use of computer models that optimize the friction properties of diamond-like coatings used in hard disk drives.

© Janka Dharmasena/iStock/Thinkstock

But because these coatings contain amorphous carbon atoms that produce rough, nanoscale textures, it is difficult to optimize their friction properties using classical theories designed for macroscopic objects.

By performing atom-level simulations of nanoscale friction, Ling Dai and co-workers from the A*STAR Institute of High Performance Computing in Singapore have now uncovered critical clues for designing better systems to lubricate and protect DLC coatings (1).

Perfluoropolyether (PFPE) is a Teflon-like polymer that is commonly sandwiched between DLC-coated substrates to reduce friction and protect against damage. Understanding the friction mechanisms between these ultrathin films is tricky; these materials have contrasting hard and soft mechanical properties, and the sandwich arrangement obscures any direct observation of atomic structure and activity.

To better understand how nanoscale lubrication works in microdevices, the researchers constructed an atomic DLC–PFPE–DLC triple layer using a three-dimensional computer modeling program. They set one DLC slab as a substrate and the other as a ‘slider’.

They then used molecular dynamics techniques to simulate how the lube film responds when the slider moves. However, it was challenging to describe the atomic interactions in this complex material, and so Dai’s team developed hybrid computations that combined several potential energy expressions to replicate the many-body forces in this system.

Simulating frictional motions at different speeds and PFPE film thicknesses revealed that the lubricating film behaves as a solid — the polymer retained its shape without deforming from internal shearing. However, the lubricating film displayed two distinct and competitive modes of motion at an interface: a ‘stick–slide’ action that produced jerky, stepwise displacements, and a continuous motion that caused the film to slide with fluctuating velocities.

The team’s analysis showed that these two types of motions switched on or off depending on adhesion factors, such as thermal vibrations and the interfacial roughness.

After mapping the local friction forces along the sliding interfaces, the researchers discovered a way to link the law describing macroscopic friction to the nanoscale using a simple mathematical modification — a finding with practical importance for the surface engineering of DLC coatings.

“Because our model closely resembles the materials used in industrial applications, this work can serve as a guide for future experimental developments,” says Dai.

The A*STAR-affiliated researchers contributing to this research are from the Institute of High Performance Computing

Reference

(1) Dai, L., Sorkin, V., Sha, Z. D., Pei, Q. X., Branico, P. S. & Zhang, Y. W. Molecular dynamics simulations on the frictional behavior of a perfluoropolyether film sandwiched between diamond-like-carbon coatings. Langmuir 30, 1573–1579 (2014).

A*STAR Research | Research SEA News
Further information:
http://www.research.a-star.edu.sg/research/7016
http://www.researchsea.com

More articles from Materials Sciences:

nachricht Nanoscientists develop the 'ultimate discovery tool'
24.06.2016 | Northwestern University

nachricht Researchers find better way to 'herd' electrons in solar fuel devices
21.06.2016 | University of British Columbia

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: First experimental quantum simulation of particle physics phenomena

Physicists in Innsbruck have realized the first quantum simulation of lattice gauge theories, building a bridge between high-energy theory and atomic physics. In the journal Nature, Rainer Blatt‘s and Peter Zoller’s research teams describe how they simulated the creation of elementary particle pairs out of the vacuum by using a quantum computer.

Elementary particles are the fundamental buildings blocks of matter, and their properties are described by the Standard Model of particle physics. The...

Im Focus: Is There Life On Mars?

Survivalist back from Space - 18 months on the outer skin of the ISS

A year and a half on the outer wall of the International Space Station ISS in altitude of 400 kilometers is a real challenge. Whether a primordial bacterium...

Im Focus: CWRU physicists deploy magnetic vortex to control electron spin

Potential technology for quantum computing, keener sensors

Researchers at Case Western Reserve University have developed a way to swiftly and precisely control electron spins at room temperature.

Im Focus: Physicists measured something new in the radioactive decay of neutrons

The experiment inspired theorists; future ones could reveal new physics

A physics experiment performed at the National Institute of Standards and Technology (NIST) has enhanced scientists' understanding of how free neutrons decay...

Im Focus: Discovery of gold nanocluster 'double' hints at other shape changing particles

New analysis approach brings two unique atomic structures into focus

Chemically the same, graphite and diamonds are as physically distinct as two minerals can be, one opaque and soft, the other translucent and hard. What makes...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ERES 2016: The largest conference in the European real estate industry

09.06.2016 | Event News

Networking 4.0: International Laser Technology Congress AKL’16 Shows New Ways of Cooperations

24.05.2016 | Event News

Challenges of rural labor markets

20.05.2016 | Event News

 
Latest News

Nanoscientists develop the 'ultimate discovery tool'

24.06.2016 | Materials Sciences

Russian physicists create a high-precision 'quantum ruler'

24.06.2016 | Physics and Astronomy

Hubble confirms new dark spot on Neptune

24.06.2016 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>