BAM continues amazing development

A material that rivals industrial diamond in hardness continues to amaze the researchers who developed it and attract interest from a variety of industrial sectors. The material represents a breakthrough technology that could have a substantial impact on the machining industry, which spends $300 billion each year in labor and overhead in the United States alone.

But hardness is only one of several unique properties possessed by the boron-aluminum-magnesium alloy, nicknamed "BAM." Preliminary tests show it stands up well in cutting both concrete and stainless steel, giving it a definite advantage over diamond-coated cutting tools in slicing up steel-reinforced concrete.

"Diamond does a good job of cutting concrete and masonry," says researcher Bruce Cook, "but wears quickly when cutting steel due to the chemical reaction between the carbon in the diamond and the iron in the workpiece. Our alloy seems to cut both concrete and steel equally well without much wear."

Though Cook and fellow researchers Alan Russell and Joel Harringa expected BAM to perform well as a cutting tool, they were surprised to find that the material cuts without getting hot. Even when the cutting edge is spinning off red-hot ribbons of lathe-turned stainless steel (somewhere around 700 degrees Celsius, or 1,292 degrees Fahrenheit), the tool stays cool enough to touch with a bare fingertip.

"There's very little heat transport, and we think that's due to fine grain size and the complex crystal structure within the material," says Cook. Bruce Harmon, Ames Lab deputy director and director of the Lab's Condensed Matter Physics Program, and graduate student Younben Lee are also conducting further calculations on the fundamental electronic structure. "We're interested to see if there's a relationship between the electrical transport and thermal transport that may help explain how ultrahard materials perform," Cook adds.

Cook's research team has also boosted the scale of production of the material, in part to keep up with requests for samples. Button-sized samples have been replaced by much larger wafers, nearly 2 inches in diameter and about three-quarters of an inch thick. But given BAM's low density (about 2.5 grams/cm3), the wafers lack the expected heft of conventional tungsten carbide used to slice through concrete and steel.

Since discovery of the material was first announced in October 1999, more than 100 companies and research facilities have requested samples.

While in-house testing continues, including recent successful trials in machining titanium, Cook hopes to learn as much or more from the various companies that have received samples. For example, a manufacturer of tooling for industrial woodworking equipment returned a sample that had been shaped using electric spark erosion. And a producer of industrial gases and surface coatings is investigating the material as an extremely durable coating for various industrial applications.

"They may not realize it, but these companies are providing us with valuable information," Cook says. "It gives us a much broader perspective. At the same time, most of the research and development is being conducted by scientific staff so they can supply test data to support the various applications. It really helps our understanding of the material."