Coloring Properties of Various High‐Nitrogen Compounds in Pyrotechnic Compositions

Abstract

Strontium salts are widely used in red flame pyrotechnic compositions, usually combined with perchlorate salts as oxidizer. The potential environmental impact of perchlorate could be avoided by using high-nitrogen compounds. Therefore, the following nitrogen-rich strontium salts were prepared and characterized: strontium tetrazolate pentahydrate (1), strontium 1methyl-5-nitriminotetrazolate monohydrate (2), and strontium 1-(2-chloroethyl)-5-nitriminotetrazolate monohydrate (3). Their combustion behavior and both color intensity and purity were investigated in pyrotechnics. These results were compared with the US Army in-service signal formulation. Pyrotechnic compositions which are used for producing green flame colors contain barium salts, usually highly water-soluble and toxic barium nitrate, Ba(NO 3 ) 2 . In this research project copperbased colorants with energetic anions or ligands were developed. The compounds diammine bis(tetrazolato)amine copper(II) (4), diaqua copper(II) di(1-methyl-5-aminotetrazole) nitrate (5), diaqua copper(II) tetra(1-methyl-5-aminotetrazole) nitrate (6), and tetrammine copper(II) dinitramide (7) were synthesized and characterized.

High‐Performing Red‐Light‐Emitting Pyrotechnic Illuminants through the Use of Perchlorate‐Free Materials

“…Mirroring the previous work involving KClO 4 ‐free red‐light‐emitting M126 A1 development,7 the first approach was to use strontium bis(1‐methyl‐5‐nitriminotetrazolate) monohydrate ( 1 ) as the KClO 4 replacement (Figure 1). This compound is highly energetic (Δ c H o =−2 901.2 kJ mol −1 ), and is relatively stable to various ignition stimuli 14. The highly energetic nature of bis‐tetrazolate 1 , coupled with its release of copious amounts of nitrogen gas to provide flame expansion, made this compound a sensible choice for formulation studies.…”

High‐Nitrogen‐Based Pyrotechnics: Longer‐ and Brighter‐Burning, Perchlorate‐Free, Red‐Light Illuminants for Military and Civilian Applications

“…Because potassium perchlorate is an energetic oxidizer and decomposes in an exothermic process, [6] to remove it from the formulation means that energy is removed from the pyrotechnic system. As described and demonstrated previously, [11,12] strontium bis(1-methyl-5-nitriminotetrazolate) monohydrate (1, Figure 1), was selected to replace potassium perchlorate because of the high-energy nature, stability toward various ignition stimuli, and because of the potential to contribute to redlight emission.…”

“…HHSs are used in training and combat situations for the purposes of signaling military and allied personnel and aircrafts. Although Klapçtke and ARDEC were recently successful in developing perchlorate-free M126A1 red-light-emitting formulations on a small scale, [11,12] successful formulation development at the prototype level (i.e., production scale) with high-nitrogen compounds had never been done. Because substantial differences in pyrotechnic performance can arise as one moves from small-scale testing to prototype testing, it is imperative that formulations be proven out at the prototype level because these tests are indicative of how a formulation will behave when produced and put into a military item.…”

Advances Toward the Development of “Green” Pyrotechnics

“…Another green-light emitter, metastable CuOH, forms when copper-containing compounds are combusted in the presence of a hydrogen-and oxygen-rich environment. Klapötke and Stierstorfer have synthesized a number of high-nitrogen containing copper salts and these compounds are reported to generate green light upon combustion [45,46].…”