Readers have expressed significant interest in our Dec. 5 post on the world’s third hardest material – BAM.

Currently being tested at DOE’s Ames Laboratory as a nanocoating for machinery, BAM is thought to reduce machine friction and wear and, thus, make machinery operate more smoothly and energy efficiently.

Because inquiring minds wanted to know more about BAM, I went back to the Ames researchers who discovered the new material and asked a few more questions. Here’s what I learned:

1.  There’s more than one type of BAM nanocoating. In fact, Alan Russell, an Ames researcher, co-discoverer of BAM and a professor of materials science and engineering at Iowa State University, says there’s “quite a range of compositions.”

Russell notes the use of pure AIMgB14 and AIMgB14 + TiB2 with varying ratios of AIMgB14 to TiB2. He says Ames is applying it by pulsed laser deposition but it can also be applied by magnetron sputtering, a technique better suited to commercial operations.

2. Long-term testing has been conducted on a range of rotating and sliding parts. These tests have compared bare steel, steel coated with diamond-like carbon and steel coated with BAM and BAM plus TiB2.

Russell says, while all coated parts “showed improvements in mechanical-running efficiency and start-up efficiency of one to eight percent,” BAM-coated parts performed best in two out of three tests.

3. While no definite answers are in yet, researchers do have some idea why BAM is so hard and slippery. Again, Russell is our information source:

“BAM’s high hardness is believed to result primarily from short, strong boron bonds and the small grain and phase size of the BAM and  TiB2materials.”

He believes BAM’s slipperiness is the result of the “formation of hydrated boron oxide forming at the material’s surface from oxygen and water vapor in the air.” He notes, however, that “future tests of friction in high vacuum may refute or support [the hydrated boron-oxide] theory.”

For those of you wondering about BAM’s potential application in combustion motor applications such as two-stroke engines, there does seem to be some promise:

“It’s almost as if it’s a self-lubricating surface. You don’t need to add oil or other lubricants. It’s inherently slippery,” he says, noting that “future tests of friction in high vacuum may refute or support [the hydrated boron-oxide] theory.”

4. I asked if he was concerned that BAM might one day prove harmful to workers, Russell responded:

“While boron has some mild toxic effects in extremely high doses, it is not generally deemed a hazardous material. Normal handling of bulk borides or coated parts is not considered a workplace hazard, nor is the dispersion of boron debris during use of the products.”

5. When I asked BAM’s other co-discoverer and Ames Lab researcher Bruce Cook when BAM nanocoatings might be taken to market, he reiterated that an Iowa-based start-up company, Newtech Ceramics, had licensed the BAM technology. He added, however:

“To my knowledge, there is no material in commercial use yet, although it appears this may change during 2009.”

To review a complete and updated version of the BAM story, check out the upcoming January issue of the Bulletin, ACerS monthly member magazine.