Chemistry fights Friction
Robert Goddard's patent of the first liquid fuel rocket in 1914 marked the dawn of modern aeronautics. Since then, researchers have developed various materials and lubricants that can hold up in space and on Earth.
In November 2008, the space shuttle Endeavor visited the International Space Station to do some important repair work. A critical part of the mission was to service the station’s two rotary joints, which allow its solar-cell arrays to track the sun. Wear and damage because of friction had rendered the joints inoperable. The fix required an hours-long spacewalk and a delicate technical procedure.
But the basic idea was simple. “We sent astronauts up with a grease gun and got it moving again,” recalls Christopher DellaCorte, a senior research engineer in the Tribology & Mechanical Components Branch at NASA’s Glenn Research Center. The joints were originally installed with a gold-film solid lubricant, “but it wasn’t adequate,” he explains. “There was more rubbing in one bearing than the other, and that bearing failed. It was not the right approach.”
The space station repair was successful, but for upcoming missions DellaCorte and his colleagues are looking for materials and lubricants that can last indefinitely. “In space, we don’t have the ability to go and change the oil,” DellaCorte points out.
On Earth, friction is a physical force, like gravity, that people take for granted. But friction is incredibly costly. In machines, friction quietly steals power by wasting kinetic energy in the form of heat. What’s worse, whenever surfaces rub, friction eventually causes the materials to wear down, ending an object’s useful life.
Researchers who study friction, part of a field of mechanical engineering called tribology, say that new performance materials hold the promise of vastly reducing the effect of friction on mechanical parts, including car engines and wind turbine gears.
Visit Chemical & Engineering News to read more about the use of chemistry to minimize resistance between surfaces – both in space and on earth.
Excerpted with permission, Chemical & Engineering News
Copyright © 2010 American Chemical Society