During the last eight years, Innovative Materials and Processes (IMP) has been developing environmentally benign delays under SERDP Project WP-2519, ESTCP Projects WP18-5262, and WP20-5054. These projects have been focused on the replacement of lead, chromium VI, and perchlorates in the M201A1 and M213/M228 grenade fuzes, C70 detonators, and Cartridge Actuated Device/Propellant Actuated Device. The delay formulation developed by IMP consists of aluminum, silicon, and strontium molybdate which meet the strategic goals of the SERDP mission. This new time delay formulation eliminates environmental hazards from the entire life cycle of the cartridge items (from manufacturing to function to end of service disposal).
The research and development (R&D) approach for this effort will focus on six fundamental aspects of printed delay requirements. These fundamental aspects need to be investigated prior to preceding into a full SERDP program. This research will build a foundation for understanding the viability of printed time delays in end item cartridges through: 1. Investigation of suitable substrate material(s) with low thermal diffusivity and adequate structural integrity; 2. Investigation into the effect of binder concentration on strength and integrity of printed delay materials; 3. Testing of critical channel dimensions for stable burn rate characteristics at required temperatures; 4. Determination of an optimal slurry viscosity in order to achieve an optimal high solids loading that prevents constituent stratification during dosing and processing; 5. Investigation of epoxy encapsulation for water resistance and increased printed material resistance to vibration and other external stimuli; and 6. Developing a new pyrotechnic time delay testing procedure and requirements.
There are several significant benefits to the Department of Defense (DoD) with this effort. Successfully demonstrating a printed green delay formulation that meets the requirements of the currently used pyrotechnic time delay compositions, may lead to the elimination of hexavalent chromium, lead, and perchlorates in a wide range of DoD weapon and system platforms. IMP believes that this R&D effort will result in the reduction of the number of environmentally unacceptable pyrotechnic delay formulations currently used by the DoD. This will be accomplished by optimization of geometry of the printed channel in a suitable substrate. By extending or reducing the length of the channel, a longer or shorter burn time can be realized using the same formulation. A redundancy of function can also be achieved for critical man-rated cartridges by designing built-in dual channels. This novel approach will provide an additional level of safety and reliability for warfighters. Automating delay cartridge production will eliminate these current production issues associated with time delay cartridges (e.g., waste stream of rejected lots and washing, human exposure, and end of service-life demilitarization). This will be accomplished by using environmentally acceptable time delay formulations, which will reduce environmental exposure to hazardous materials. It will also ensure long term viability of these critical safety components.