Performance and Aging of Mn/MnO2 as an Environmentally Friendly Energetic Time Delay Composition

The Mn/MnO2 reactive system was investigated as a suitable replacement for the traditional W/BaCrO4/KClO4/diatomaceous earth delay composition. The delay performance, ignition sensitivity, and aging characteristics were examined in aluminum microchannels similar in diameter to common delay housings (4.7 mm). Stoichiometries with measured combustion temperatures between 1358 and 2113 K were self-sustaining with combustion velocities ranging from 2.4 to 7.3 mm s-1. The Mn/MnO2 system produced less gas than W/BaCrO4/KClO4/diatomaceous earth compositions allowing consideration for use in sealed delay housings. Accelerated aging at 70 deg. C and 30% relative humidity for 8 weeks resulted in no measurable loss of performance. Safety characterization showed that this composition is not sensitive to ignition by friction or electrostatic stimuli. The combustion products (as determined by X-ray diffraction) appear to be benign based on current regulations. Therefore, the Mn/MnO2 system appears to be a suitable low gas-producing, nonsensitive, less toxic delay composition with good longevity. The original document contains color images. Published in ACS Sustainable Chemistry and Engineering, v2 p1312-1317, 2014.