Description:
TECHNOLOGY AREA(S): Electronics
OBJECTIVE: To develop propellant material additives for electric ignition applications.
DESCRIPTION: DoD has a need for a propellant material that can be ignited with an electrical impulse (arc/spark) and which can be used in electric ignition systems. Such materials are highly desired for multiple reasons such as: removing primary energetics, reducing sensitivity, eliminating mechanical/impact initiation and to increase initiation rate. The ideal electric impulse would have a small time and voltage profile. Electric ignition offers the potential for a more uniform ignition of a monolithic, cast-cured, propellant body relative to what is possible with percussion style primers that are optimized for igniting the loose packed ball and flake propellant found in conventional small arms ammunition. The primary benefit of more uniform ignition is a reduction in both interior ballistics and projectile muzzle variabilities, which ultimately translates into reduced projectile dispersion. For example, one of the applications is use of electrical ignition in caseless rounds where electrical ignition reduces the occurrence of unconsumed propellant which poses a serious threat to weapon reliability as it can accelerate barrel fouling and/or cause subsequent rounds to jam while being chambered. The key phenomena of electric ignition is well described by Lee who probed the response of electric discharge through solid propellants.(1,2) Lee observed that electric discharge into solid propellants results in the formation of arc channels where the dielectric binder breakdowns and plasma generation occurs along the path of discharge. Such plasma generation results in rapid combustion occurring throughout the propellant at equivalent times. Electrical conductivity is one of the important energetic material properties that can be used to tailor the electric ignition process and is an active research area.(3,4) The small business would develop additives that would reduce the dielectric strength of the propellant material, such that an arc discharge through the material can be made at reduced power requirements and shorter time. Such materials additives could include combustible conductive materials or materials that have unique electrical properties under discharge (e.g. semiconductors).
PHASE I: The offeror will survey a list of initial additive candidates which can be used as dopant to the propellant energetic materials (i.e. B/KNO3 Black Powder, Benite) for electrical ignition applications. The dopant amount would be restricted to less than 2% (1% preferred) by weight of the propellant material. The offeror will characterize and demonstrate reduction in the dielectric strength of the propellant material in a pelletized form factor.
PHASE II: On successful demonstration in Phase I, the offeror will use the derived formulations to prepare larger form factor samples and demonstrate successful initiation by an electrical impulse in ambient conditions. The offeror will design and fabricate the characterization technique which captures the mechanism affecting the propellant material properties, for example measuring the voltage, current and time profiles of the electrical impulse. The open-air characterization can also be performed in collaboration with NSWC IHEODTD.
PHASE III: The offeror will work with available funding sources to transition capability into practical use within Army/DoD simulation systems, while consider options for dual use applications in broader domains including state/local governments and commercial.
REFERENCES:
1: Lee, R. J., Tasker, D. G., Forbes, J. W. and Beard, B. C. (1991). Ignition of PBXW-115 due to electrostatic discharge. Naval Surface Warfare Center Indian Head Division Report No. NSWC-TR-89-212.
2: Lee, R. J. (1996). Ignition in solid energetic materials due to electrical discharge. Naval Surface Warfare Center Indian Head Division Report No. NSWC-IHTR-1925.
3: Beloni, E., Santhanam, P. R., & Dreizin, E. L. (2012). Electrical conductivity of a metal powder struck by a spark. Journal of Electrostatics, 70(1), 157-165.
4: Weir, C., Pantoya, M. L., Ramachandran, G., Dallas, T., Prentice, D., & Daniels, M. (2013). Electrostatic discharge sensitivity and electrical conductivity of composite energetic materials. Journal of Electrostatics, 71(1), 77-83.
KEYWORDS: Electrical Ignition, Propellant, Powder Electrical Conductivity, Powder Additives, Semi-conductors, Propellant Electrical Properties, Temperature, Electrostatic Discharge, Propellant Binder, ESD Ignition, Arc Channel, Energetic Material
