Nanoscale Coating Reduces Friction, Boosts Industrial Energy Efficiency

nanoscale

Friction is the bane of any machine.

When moving parts are subject to friction, it takes more energy to move them, the machine doesn’t operate as efficiently, and the parts have a tendency to wear out over time.

But if parts could be manufactured with tough, “slippery” surfaces, there would be less friction, requiring less input energy, and parts would last longer.

Researchers at the U.S. Department of Energy’s (DOE) Ames Laboratory, in collaboration with DOE’s Oak Ridge National Laboratory (ORNL), Eaton Corporation and Greenleaf Corporation, have developed just such a coating, nicknamed BAMC, that exhibits exceptional hardness and an even lower coefficient of friction than Teflon®.

“When a hydraulic pump moves fluid, the friction between the turbine vanes and the housing translates into additional torque needed to operate the pump, particularly at startup,” said Bruce Cook, the Ames Laboratory scientist who discovered BAMC along with Ames Lab colleague and Iowa State University professor of materials science and engineering Alan Russell. “It takes extra energy to get the pump started, and you can’t run it at its optimum (higher speed) efficiency because it would wear out more quickly.”

Coating the blades to reduce friction and increase wear resistance could have a significant effect in boosting the efficiency of all kinds of industrial and commercial pumps.

According to Cook, a modest increase in pump efficiency could reduce U.S. industrial energy usage by 31 trillion BTUs annually by 2030, or a savings of $179 million a year.

BAMC is different from most superhard materials, such as diamond, that have a simple, regular and symmetrical crystalline structure. Instead, BAMC’s structure is complex, unsymmetrical, and its lattice contains gaps.

As for its slipperiness, the researchers speculate that boron oxidation takes place on the surface, and these tiny amounts of boron oxide attract water molecules from the air to make the surface slippery.

“It’s almost as if it’s a self-lubricating surface,” Russell said. “It’s inherently slippery, so you don’t need to add oil or other lubricants.”

Using a technique called pulsed laser deposition, the Ames Laboratory team deposited an ultra-thin layer of BAMC on hydraulic pump components as well as tungsten carbide cutting tools.

Initial tests at ORNL, one of the nation’s leading friction and wear research facilities, showed a decrease in friction relativetoanuncoatedsurface of at least an order of magnitude with the AlMgB14-based coating. In preliminary tests, the coating also appears to outperform other coatings such as diamond-like carbon and TiB2.

BAMC is licensed to an Iowabased startup company located in Des Moines, and several leading equipment and tool manufacturers plan to use BAMC in their products.