March 9, 2008
Written by Cory Chandler
Few professionals practice the motto, “Safety First,” more than Michelle Pantoya. But then again, few people have the job of detonating highly energetic materials in their workplace. This mechanical engineering professor observes reactions between energetic materials in her Texas Tech laboratory – sometimes with unpredictable results. While working with a unique sample of nanoparticles, Pantoya and her lab assistant, Emily Hunt, came across such a reaction.
One more millisecond... One more millisecond... One more millisecond...
Right before detonation I still feel the rush of excitement. No matter how many times I’ve done this, it always hits me. I think that is a big draw for students in this field – the allure of the unknown.
The project began when we received a very unique sample of aluminum nanoparticles from the U.S. Navy’s Indian Head research division, which is responsible for developing, testing and manufacturing new-generation explosives and propellants.
The aluminum was different from anything we had ever used because it had been coated with synthetic Teflon, which, when burned, turns to gas. We predicted this increased level of gas would cause a reaction more aggressive than any previously observed of its kind.
We planned to ignite our material from a safe distance using a remote-controlled laser. A camera filming at 150,000 frames per second was in place to capture the most intricate details of the reaction.
Emily had meticulously measured and prepared our explosive mixture – a responsibility that involves great care and focus. It was almost time for detonation. Was everything in the right place? Had we followed all of the correct procedures?
On came the laser – no time for second guessing now. I held my breath, waiting.
Thick black smoke poured from the reaction, but where was the explosion? Certainly it was about to really go off. Just give it a little more time. Then I heard what we had been waiting for. Well, sort of. It wasn’t the loud, rewarding bang I expected to pierce my ears. Instead, it was more of a fizzling ppppfffffhhhh…
Yes, quite anti-climactic.
As the smoke cleared, we saw what remained. Something completely out of the ordinary.
Unlike most reactions, which explode and disperse the reactants like dust in the wind, this reaction had left something behind. The small five-millimeter pellet we detonated had actually grown to almost 20 millimeters in length!
The remaining material, Nickel Aluminide, was unlike anything I had ever seen. When I picked it up in my hand, it felt like a metal, yet it was extremely porous. Lab tests would later show that our synthesized material had the highest surface area of any known porous metallic alloy. A material with these characteristics would be great for a variety of applications, including joint implants – where a strong, porous material would facilitate bone growth.
Using this reaction, we have since been able to create many new materials with different metal combinations; but there are so many that remain to be tried.
The allure of the unknown…
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