PICATINNY ARSENAL, N.J. -- Three Picatinny Arsenal employees were recently granted a patent for their work on boron carbide-based pyrotechnic time delays. The employees include Anthony Shaw, a Picatinny chemist, Jay Poret, a physical scientist and Christopher Csernica, a chemical engineer.
The three employees are with the U.S. Army Armament Research, Development and Engineering Center's Pyrotechnics Technology and Prototyping Division at Picatinny Arsenal.
Their patent was for a precise, slow burning, pyrotechnic delay composition that contained three components: 8 to 55 weight percent boron carbide fuel, 35 to 82 weight percent sodium periodate oxidizer, and PTFE (a fluorinated polymer commonly called TEFLON).
The PTFE acted as both a pyrotechnic oxidizer and a lubricant, so that the resulting composition has surprisingly good mechanical properties, said Shaw. For example, the pyrotechnic blend could be pressed to a higher consolidated density with ordinary loading force, a more desirable process bringing the benefits of minimal wear on the tooling used for pressing and excellent consistency in powder mixing.
"This project started in 2011, although the patent covers work that occurred mostly in 2012 and 2013," said Shaw.
"The goal was to replace the toxic chemicals in the hand-held signal delay with benign alternatives. In fact, this is the second patent we received for work on this project."
The first patent received was patent 9,193,638 for condensed phase energetic time delay compositions.
"Unlike the first patent, this one originated from work that occurred entirely at ARDEC," said Shaw. "The inventive delay formulation which contains boron carbide, a hard ceramic material, sodium periodate, an oxidizing material that is relatively new to pyrotechnics, and PTFE (a fluorinated polymer) has an interesting developmental story.
"Each component, or combinations of the components, were being experimented with for completely different applications in the Pyrotechnics Division at the time," Shaw added. "We were examining boron carbide for use in smoke-producing compositions, as well as in green-light-emitting flares.
"Also in our division, Jared Moretti was developing flash/incendiary compositions containing periodate salts. This inspired us to choose sodium periodate as the main oxidizer for the compositions," Shaw said.
The inventive delay formulations started out as tracer compositions for ammunition.
"Chris Csernica and I observed that certain combinations and ratios of the materials were able to continue burning for long periods of time inside small metal housings, and that's exactly what is needed for a reliable pyrotechnic delay," said Shaw. "After that, Jay Poret and I spent over a year conducting many tests to prove the concept, culminating with tests at the contractor site in fully assembled hand-held signals, which were successful. We also documented our work in several articles.
"During our experiments we were able to produce delay columns that burned for very long periods of time. Both Tony and I joked that we could go have a cup of coffee and after we came back the delay would still be burning," said Poret.
"There are many aspects of the formulation that provide non-obvious benefits for the intended application," Shaw continued. "We are very fortunate to have managers in the Pyrotechnics Division, Andy Zimmer and Jim Wejsa, who encourage and support our exploratory R&D (research and development) efforts, which lead to new discoveries and inventions in the area of energetic materials."
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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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