Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Using nature as a model for low-friction bearings

14.05.2014

Lubricants are required wherever moving parts come together.

They prevent direct contact between solid elements and ensure that gears, bearings, and valves work as smoothly as possible. Depending on the application, the ideal lubricant must meet conflicting requirements. On the one hand, it should be as thin as possible because this reduces friction.


Thanks to biological lubrication natural joints move almost frictionless and withstand enormous loads.

Credit: Tom Page (https://www.flickr.com/photos/tompagenet/6957645328, https://creativecommons.org/licenses/by-sa/2.0/deed.en)

On the other hand, it should be viscous enough that the lubricant stays in the contact gap. In practice, grease and oils are often used because their viscosity increases with pressure.

Biological lubrication in contrast is much more efficient. In joints, a thin, watery solution prevents friction. The thin film stays where it should thanks to a trick of nature. A polymer layer is anchored to the cartilage at the end of bones. Polymers are a string of densely packed, long-chain molecules.

They protrude from the cartilage and form "polymer brushes" which attract the extremely fluid lubricant and keep it in place at the contact point.

Over the last 20 years, numerous attempts have been made to imitate the natural model technically. But with no resounding success. The tentacle-like polymers on surfaces opposite each other tend to get tangled up in each other.

They slow each other down and detach from the surfaces. In technical systems, individual polymers that become detached are difficult to replace as they do not possess the same self-healing mechanisms as in a natural organism.

Jülich physicist Prof. Martin Müser came up with the idea of using two different polymers at the contact point to prevent the polymers becoming entangled. "Using supercomputers, we simulated what would happen if we applied water-soluble polymers to one side and water-repellent polymers to the other side," says head of the NIC (John von Neumann Institute for Computing) group Computational Materials Physics at the Jülich Supercomputing Centre (JSC)."

This combination of water-based and oil-based liquids as a lubricant reduced the friction by two orders of magnitude – around a factor of 90 – compared to a system comprising just one type of polymer."

Measurements with an atomic force microscope at the University of Twente in the Netherlands verified the results. "The two different phases of the liquid separate because they repel each other. This simultaneously holds the polymers back and prevents them from protruding beyond the borders," says Dr. Sissi de Beer, who recently moved from Müser's group to the University of Twente.

The low-friction two-component lubricant is interesting for numerous applications. One example are simple piston systems, like syringes, which are used to precisely administer even tiny amounts of a drug.

Above all, the new process could provide low-friction solutions where high pressures and forces occur locally – for example, axle bearings and hinges. For the most common lubricant – engine oil – an alternative has yet to be found; conventional polymer brushes are unable to withstand the high temperatures.

Tobias Schlößer | Eurek Alert!
Further information:
http://www.fz-juelich.de/portal/DE/Presse/Pressemitteilungen/PM_node.html

Further reports about: Polymers cartilage factor friction liquids lubricant organism pressure surfaces valves

More articles from Life Sciences:

nachricht Moth takes advantage of defensive compounds in Physalis fruits
26.08.2016 | Max-Planck-Institut für chemische Ökologie

nachricht Designing ultrasound tools with Lego-like proteins
26.08.2016 | California Institute of Technology

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Streamlining accelerated computing for industry

PyFR code combines high accuracy with flexibility to resolve unsteady turbulence problems

Scientists and engineers striving to create the next machine-age marvel--whether it be a more aerodynamic rocket, a faster race car, or a higher-efficiency jet...

Im Focus: X-ray optics on a chip

Waveguides are widely used for filtering, confining, guiding, coupling or splitting beams of visible light. However, creating waveguides that could do the same for X-rays has posed tremendous challenges in fabrication, so they are still only in an early stage of development.

In the latest issue of Acta Crystallographica Section A: Foundations and Advances , Sarah Hoffmann-Urlaub and Tim Salditt report the fabrication and testing of...

Im Focus: Piggyback battery for microchips: TU Graz researchers develop new battery concept

Electrochemists at TU Graz have managed to use monocrystalline semiconductor silicon as an active storage electrode in lithium batteries. This enables an integrated power supply to be made for microchips with a rechargeable battery.

Small electrical gadgets, such as mobile phones, tablets or notebooks, are indispensable accompaniments of everyday life. Integrated circuits in the interiors...

Im Focus: UCI physicists confirm possible discovery of fifth force of nature

Light particle could be key to understanding dark matter in universe

Recent findings indicating the possible discovery of a previously unknown subatomic particle may be evidence of a fifth fundamental force of nature, according...

Im Focus: Wi-fi from lasers

White light from lasers demonstrates data speeds of up to 2 GB/s

A nanocrystalline material that rapidly makes white light out of blue light has been developed by KAUST researchers.

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

The energy transition is not possible without Geotechnics

25.08.2016 | Event News

New Ideas for the Shipping Industry

24.08.2016 | Event News

A week of excellence: 22 of the world’s best computer scientists and mathematicians in Heidelberg

12.08.2016 | Event News

 
Latest News

Symmetry crucial for building key biomaterial collagen in the lab

26.08.2016 | Health and Medicine

Volcanic eruption masked acceleration in sea level rise

26.08.2016 | Earth Sciences

Moth takes advantage of defensive compounds in Physalis fruits

26.08.2016 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>