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 °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.

Replacement reactive systems for the tungsten delay composition (W/BaCrO4/KClO4/diatomaceous earth) are needed due to recent concerns over the toxicity of hexavalent chromium and perchlorates. Systems based on condensed phase reactions, that are typically used in combustion synthesis (e.g., Ti/C or Ni/Al) are of interest as replacements due to their wide range of combustion velocities and potentially low environmental impact. In this work, the combustion characteristics of the Ti/C‐3Ni/Al reactive system were examined in microchannels with inner diameters ranging from 3.0–6.0 mm (i.e., similar to that of a common delay housing). It was found that this reactive system could be tailored to overcome the heat losses associated with small diameter microchannels by changing the relative amounts of Ti/C and 3Ni/Al. At 40 wt.‐% Ti/C content, the failure diameter was found to be between 3.0 and 4.0 mm, while at 30 wt.‐% Ti/C the failure diameter was between 4.8 and 6.0 mm. Measured combustion temperatures in metal microchannels were approximately 1700 K while those of unconfined pellets were around 100 K greater. Increasing Ti/C content resulted in faster combustion velocities while decreasing microchannel diameter resulted in slower combustion velocities. At these small sizes the effects of adding a thermal barrier (specifically Grafoil™) to minimize radial heat losses to the microchannel were shown to be minimal with respect to combustion velocity. The Ti/C‐3Ni/Al system was shown to be a suitable delay fuze composition with tunable combustion velocities ranging from 2.1–38.1 mm s−1 in aluminum microchannels with diameters ranging from 4.0–6.0 mm.

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Novel yellow-light emitting pyrotechnic compositions absent perchlorate oxidizers were investigated for use in the Mk 144 marine smoke and illumination signal. In laboratory-scale testing, three candidate formulations met or surpassed performance metrics of luminous intensity, dominant wavelength, color purity, and burn time when compared to a mock Mk 144 formulation which currently utilizes the environmentally hazardous potassium perchlorate. Also, one identified formulation does not utilize any barium compounds which may be the focus of future regulations. Furthermore, these candidate systems exhibited similar insensitivity to electrostatic, friction, and impact ignition stimuli in comparison to the mock Mk 144 formulation. Therefore, replacement formulations for the Mk 144 marine smoke and illumination signal have been identified with increased performance, environmental sustainability, and acceptable safety characteristics.

In this work, the combustion characteristics of the exothermic systems Ti/C, Ni/Al, 3Ni/Al and combinations thereof, are examined in small diameter aluminum tubes (3-6 mm ID). Tailoring the overall exothermicity of the reactant system is accomplished by varying the reaction combination, stoichiometry, and the addition of alumina as a diluent. For the combined reactive system, Ti/C-3Ni/Al, it is shown that at 40 wt.% Ti/C content, the failure diameter lies between 3 and 4 mm. While at a Ti/C content of 30 wt.%, complete combustion front propagation is only observed for tube diameters of 6 mm. For the more exothermic system, Ti/C-Ni/Al, studied at a diameter of 4.8 mm, the addition of low levels of alumina as a diluent is shown to drastically alter the combustion front velocity, resulting in extinction with an increase from 2 to 2.5 wt.% addition. The addition of a thermal barrier (Grafoil TM) for Ti/C-Ni/Al (15/85 wt.%) diluted with 2 wt.% Al 2 O 3 , results in an increase in propagation rate and the range of packing densities that complete propagation is observed; the effects of Grafoil TM on the reactive composition Ti/C-3Ni/Al (35/65 wt.%) are not as pronounced.