PICATINNY ARSENAL, N.J. -- Two employees from the U.S. Army Armament Research, Development and Engineering Center were among a group of four individuals that recently received a patent for their work on condensed phase energetic time delay compositions.
Many of today's pyrotechnic time delay compositions contain environmentally hazardous and toxic materials including heavy metals, chromates (containing hexavalent chromium), and perchlorates (salts derived from perchloric acid.) Thus, researchers at ARDEC began to look for a new compositions.
Anthony Shaw, a chemist with ARDEC's Pyrotechnics Technology and Prototyping Division, along with Jay Poret, a physical scientist, were the two U.S. Army employees to be granted the U.S. patent.
"This project began in late 2010, and it was our first collaboration with Professor Lori Groven," said Shaw.
"At the time, Professor Groven was a research scientist at Purdue University. She is now a professor at the South Dakota School of Mines and Technology. Most of the work for this particular project was done when she was still at Purdue."
"One of the co-inventors, Eric Miklaszewski, was a graduate student at the time of this work. It was a large part of his doctoral dissertation. He now works as an engineer for the Navy, in Crane, Indiana," Shaw said.
Both Groven and Miklaszewski are listed at holders of the patent along with Poret and Shaw. Patent number 9,193,638 was filed in June of 2013 and approved on Nov. 24, 2015.
"The motivation was to find environmentally benign replacement compositions for use as energetic time delays," said Shaw.
"These compositions are commonly used in simple fuzes, for signaling devices, smoke grenades, and hand grenades, for example. They are dense compacts of powdered materials that burn from one end to another, providing the desired time delay. They are simple, inexpensive, and rugged. These characteristics have prevented them from being replaced by electronic time delays for inexpensive munitions, so far."
"Additionally, these kinds of delays do not require an external power source. Since pyrotechnic delays are chemical in nature they are always ready at a moment's notice. No batteries or other kinds of external power are required to activate them. This is very important for the Soldier when using these items in the battlefield," said Poret.
The group set out to find an alternative energetic delay composition that would overcome some of the potential hazards or risks associated with working with these materials.
"Unfortunately, the currently used compositions contain objectionable and toxic components such as hexavalent chromium, and perchlorate salts. These chemicals pose risks to production personnel, and can also contaminate training ranges, where so many of these small items are used," Shaw said.
"These particular compositions are interesting from the standpoint of pyrotechnics. Most pyrotechnic compositions contain a fuel and an oxidizer. These compositions contain just metals and carbon, and are more closely related to compositions for the synthesis of ceramic materials. The components are just nickel, aluminum, titanium, and carbon. In the reaction, a nickel-aluminum alloy is formed, as well as titanium carbide. Importantly, there is no hexavalent chromium or perchlorate."
The group found that this reactive system could be tailored to overcome the heat losses associated with small diameter microchannels by changing the relative amounts of titanium, carbon, nickel, and aluminum.
"We were able to show that minor modifications to the compositions can provide a wide range of time delays, so the system may be tuned to provide the desired time," Shaw said.
"This achievement is a good example of the benefits of collaborative projects involving academia. We continue to work with Professor Groven and her students on a number of related projects. The result is faster technology development, and a better fundamental understanding of the physical and chemical processes involved."
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The U.S. Army Armament Research, Development and Engineering Center is part
of the U.S. Army Research, Development and Engineering Command, which has
the mission to ensure decisive overmatch for unified land operations to
empower the Army, the joint warfighter and our nation. RDECOM is a major
subordinate command of the U.S. Army Materiel Command.
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