New metal heals itself

August 15, 2010 at 12:00a.m.

Milwaukee Journal Sentinel

MILWAUKEE

In the film “Terminator 2: Judgment Day,” the battle wounds of a liquid-metal man could heal themselves in seconds.

Now, University of Wisconsin-Milwaukee scientists have developed self-healing metals that could be useful on the battlefield. They also could be used for quick repairs in machines ranging from automobiles to power-plant turbines.

It’s all part of research taking place at UW-Milwaukee, which has received a $1.2 million U.S. Army grant to find ways that manufacturers and foundries could use advanced materials in their products.

The goal is to gear up full-scale production of some materials that, until now, have only been produced in a laboratory.

It could give Wisconsin companies a competitive advantage, said Michael Lovell, dean of the university’s College of Engineering and Applied Science.

Companies are asking for stronger, lighter, better materials they could use with processes they already have.

With self-healing metals, cracks repair themselves. The repair might not be permanent, but it’s strong enough for a temporary fix.

The healing is accomplished by including microscopic “balloons” in metals while they’re still in liquid form. The balloons burst if the finished metal product is damaged, causing the materials inside to leak out and fill the cracked area.

Even bullet holes are healed, almost instantly, in self-healing polymers.

With self-healing concrete, cracks fix themselves. Only water and carbon dioxide are needed to trigger the process.

Some advanced materials could be good for public health and the environment. The university’s research, for example, has shown that fly ash — a byproduct of coal-burning power plants — can be blended with aluminum or lead to make inexpensive composites that are lightweight and have high-impact resistance.

The university has helped Wisconsin foundries become suppliers of composite castings.

It has produced a self-lubricating metal that could be used in engines and, on a small scale, it has produced self-healing metal.

Through the $1.2 million grant, UW-Milwaukee will seek ways to get laboratory-proven materials into full-scale production.

“It is the scaling-up process that is the challenge,” Lovell said.

Advanced materials could help sagging foundries diversify their business because the materials could be made using conventional metal-casting techniques.

“Foundries could start making these modern products without having to update their equipment,” said Pradeep Rohatgi, a UW-Milwaukee engineering professor and director of the university’s Center for Advanced Materials Manufacturing.

The materials could be useful for the state’s defense contractors, such as Oshkosh Corp.

Oshkosh is working with the university to develop composites that are as strong as steel but lighter than aluminum.

Shaving pounds is important because the company’s military vehicles are loaded onto aircraft for delivery overseas.

Fuel mileage also could be improved through the use of lighter materials.

By using nanotechnology, where materials are altered at a molecular level, truck parts could have advanced properties but would still be easy to manufacture.

It takes care of the problem that previous composites had, said Robert Hathaway, vice president of materials and process engineering for Oshkosh Corp.

Metals and metal composites represent the largest volume of materials produced in Wisconsin.

Oshkosh and other companies, including General Motors Co. and Ford Motor Co., have helped fund the research.

Within two years, researchers could have truck parts ready for Oshkosh’s assembly line.

Self-healing metals are still a few more years away from production. But the university’s emphasis is on getting materials into commercial use rather than research for its own sake.

“It doesn’t do the Army any good if they fund research that never actually makes it to the battlefield,” Lovell said.