JUST ADD WATER!
“A part of the polishing process is sand- paper and water, and we noticed that the water was reacting with it and it was disappearing. We found out it was creat- ing hydrogen,” he said.
Te hydrogen was created during a hydro- lysis reaction: aluminum reacting with water to produce aluminum hydroxide, or aluminum oxide, plus hydrogen, Giri said. Tis reaction occurs with all alumi- num, and normally the formation of an aluminum oxide layer inhibits the creation of hydrogen. However, in the case of the nanogalvanic aluminum-based powder, the reaction was disrupted—the alumi- num oxide layer did not form.
Nanogalvanic aluminum powder’s scien- tific definition is a powder that consists of galvanic cells in nanoscale with alumi- num as the anode, coupled with another element acting as the cathode; galvanic corrosion occurs when two dissimilar metals make contact with one another in the presence of an electrolyte—any liquid that contains water—thereby forming a galvanic couple, the development team said. Tat means the powder is an elec- trochemical substance where the coupling of a positively charged electrode from the aluminum (anode) and a negatively charged electrode from another element (cathode) in water produces electricity.
“Te powder has some aluminum with some extra additional elements, so what happens is, when the water comes in contact with the powder, some of these additional elements want to basically pull electrons from the water. So it essentially caused the water to break down,” Horn- buckle said. Te water reacted with the extra elements in the powder and sepa- rated the hydrogen and oxygen. Because the reaction took place on the nanoscale, the powder could not form an encap- sulating oxide layer and it continued to
52 Army AL&T Magazine
SAFE HYDROGEN FUEL
A remote-controlled tank at ARL, powered by hydrogen-electric fuel, awaits demon- stration. Fuel systems like this one eliminate the need for high-pressure hydrogen canisters that can pose an extreme hazard on the battlefield if ruptured.
react with water, creating hydrogen. Te hydrolysis reaction in the powder occurs at room temperature without any cata- lysts, chemicals or external power, making the powder a good source of on-demand hydrogen fuel.
DEVELOPING THE TECHNOLOGY Robert Dowding, materials engineer and chief of the Lightweight and Specialty Metals branch, said that, to his knowledge, ARL is the only laboratory working on developing the nanogalvanic aluminum- based powder. “We’re doing a systematic investigation of these materials. We’re interested in what compositional range is going to work for us, what sort of micro- structures are going to be important, how
things are arranged—and then the process becomes important,” he said.
ARL is using a milling process to make the powder, which tends to be expensive, Dowding said. Te lab is looking at other methods to make the powder that would be less expensive and more commonly available. Part of that process includes partnering with industry to find better, less expensive methods of production and distribution. At the time of these inter- views, ARL has filed a patent application for the powder; once the patent has been issued, ARL will be able to license it to industry to aid its development.
“We are mandated by Congress per our mission lines to do R&D [research and
October-December 2018
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