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ramé-hart instrument co. December 2012 Newsletter
|Fact or Friction: Tribologists Use Contact Angle|
So it turns out that in the old days the
squeaky wheel got the grease. Literally. And that was how machines and
moving parts were lubricated. Around 1964 the art of lubrication began
to become a science with the help of David Tabor, a British physicist
and expert on lubricants, friction, and wear. In fact, he coined the
name for this new science Tribology.
A tribologist studies multiple dimensions of interactions between solid surfaces and is interested in reducing wear and friction (adhesion and cohesion). Surface engineering, surface finishing and the proper application of lubricants can all be fine tuned to contribute to a machine that runs longer with lower maintenance costs and with improved performance and efficiency.
Many of our customers are traditional tribologists looking for better ways to grease the squeaky wheel in the macroscopic world. They study the surface tension of lubricants and its relationship to the adhesive forces between solids. They look at wetting properties of surfaces to find better ways to reduce friction and improve wear. They are also interested in the effects of temperature on contact angle and the effects of surface roughness and structure on friction.
We also have customers who are nanotribologists. These researchers are interested in understanding friction and wear at the atomic level. Nanoelectromechanical systems and micromachine devices, for example, do not benefit from traditional lubricants which are too viscous for these applications. Nanotribology is an exciting new discipline with a bright future. I think if I were young and in college I would study to become a nanotribologist.
Superlubricity is one of the potential solutions for the nanotribologist. This low friction state can be achieved by rotating two mating nano-engineered surfaces out of phase with each other so as to prevent the hills of one surface from locking into the valleys of the other surface. This regime has been tested extensively using graphene (For more on graphene, see our August 2012 Newletter, http://www.ramehart.com/newsletters/2012-08_newsv.htm.) and graphite. Thermolubricity, friction reduction through thermal excitation at the atomic level, represents another potential solution.
Tribologists of all stripes are also interested in the wetting properties of the surfaces they are called on to study. Wetting behavior predicts friction and wear and can help the tribologist determine the best lubricant for maximum efficiency and minimal wear. Micro and nano-textured surfaces are used to improve lubricant retention. There is a correlation between surface roughness and contact angle which the tribologist finds significant. Furthermore, contact angle hysteresis can quantify defects on the surface (i.e., lack of structural homogeneity) which leads to pinning.
Researchers in Finland and at Argonne National Lab have calculated that improved surface coatings and lubricants in automobile engines and components could save the world $700 billion annually. The savings also translate to 102 billion fewer gallons of gasoline burned annually.1 A better understanding of how contact angle can lead to improvements in surface and coating design, reduce friction, improve wear and make the tribologist more successful also means big potential savings from more capable systems that require less energy.
1 Popular Science, November
2012, p40, The Fiction of Nonfriction.
|A Year in Review|
2012 has been an exciting year here at
ramé-hart. Last month we survived Hurricane Sandy, the largest Atlantic
hurricane on record. We were closed for only one day but many of our
employees lost power at their homes for as long as two weeks. We salute
them for their capacity to continue working despite the hardships. No orders
In November we announced a new product for measuring contact angle on hydrophilic surfaces using a novel overhead method. More on this in last month's newsletter (www.ramehart.com/newsletters/2012-11_news.htm).
This year we also celebrate 51 years of continuous operation. From our humble beginnings in Mountain Lakes to our current state-of-the-art facility 12 miles away in Succasunna, New Jersey, we have grown to become the world leader in contact angle. For over thirty years we only offered one model, the original classic Model 100-00 NRL Contact Angle Goniometer. Today we offer (9) different models of goniometers and tensiometers with over two dozen modular accessories and options.
As we look forward to 2013, we have new products, upgrades, and product improvements in store. Stay tuned and we will keep you up to date with our monthly newsletter, website updates, and updates on Twitter and Facebook.
Thank you for your business this year.
As we prepare to bring a close to 2012, we extend our wish for a Happy
Holiday and safe and prosperous New Year to you and your kin.