Liquid crystal lubricants promise close-to-zero frictional losses
November 12, 2008 Lubrication enables all of the world’s machinery to function, but even then, at least a quarter of all the energy is lost to friction. Despite some ingenious lubrication methods, at least 15% of the power made in a car engine is lost to friction. In most machinery, frictional losses are much higher than 15% and the heat resultant from friction generates trillions of dollars of repair and maintenance every year. Now a breakthrough in lubricant design employing liquid crystals promises a vast reduction in friction and some quite remarkable lubricants are about five years from market – oils that could reduce friction to almost zero.
Lubricants in bearings and gear units ensure that not too much energy is lost through friction. This new lubricant, developed by researchers at the Fraunhofer Institute for Mechanics of Materials IWM in Germany, uses liquid crystals like the ones used in LCD (Liquid Crystal Display) monitors. The big difference from normal lubricants is that molecules in liquid crystals have a certain orientation – you might compare them to matches with their heads all pointing in the same direction.
In a joint project with the Fraunhofer Institute for Applied Polymer Research IAP in Potsdam and the Mainz-based company Nematel, the IWM researchers are investigating which liquid crystals are most suitable for use as lubricants, and under what conditions. Their testing unit exerts a certain amount of force on a clamped metal cylinder that is moved back and forth over a supporting contact surface to enable them to measure the lubricant that yields the smallest amount of energy loss.
While the friction hardly changes when using conventional oil, it quickly drops to almost zero when liquid crystals are used. “Liquid crystals have not been suitable as a lubricant for ball bearings until now, as the contact pressure is too high – the friction does not drop far enough, says Fraunhofer’s Dr. Andreas Kailer. “For slide bearings, on the other hand, liquid crystals are the perfect solution.” Since liquid crystals have been produced mainly for monitors up to now, they have to be ultra-pure – which makes them very expensive. So the researchers now plan to simplify the synthesis process, since less pure substances are also suitable as lubricants,. “We hope to be able to market a liquid crystal lubricant in three to five years’ time,” says Kailer.
One of our favourite writers, engineer and journalist Kevn Cameron explains frictional losses particularly well here and if you like his stuff (highly recommended), check out the book of the best of his writings – he is perhaps, as one of the testimonials opines, “the finest technical writer the internal combustion press has ever known.”