SBIR-STTR Award

It is proposed use Arrested Reactive Milling (ARM), a “top-down” synthesis approach to produce energetic nanomaterials optimized to serve as burn rate modifiers for solid propellants. Boron-based B-Ti and B-Zr nanocomposites will be evaluated as candidate materials for the Phase I work, while other boron and aluminum based compositions will be addressed later. Such nanocomposite powders are expected to boost ignition rates and eliminate agglomeration of unignited aluminum particles in aluminized propellants. They will also increase the bulk burn rate of the metal fuels by modifying the temperature profile in the solid rocket motor. The overall result will be a 10% or greater increase in the experimental specific impulse. Proposed research will demonstrate the feasibility of this concept by evaluating the effect of burn rate modifier additives on agglomeration and burn rate of aluminum powders with and without the propellant binders. Compatibility of the nanocomposite burn rate modifier materials with different propellant binders will also be addressed. Finally, electrostatic discharge sensitivity of new materials will be quantified.

Keywords:
Reactive Nanocomposite, Burn Rate Modifiers, Aluminized Propellants, Aluminum Agglomeration, Specific Impulse, Arrested Reactive Milling, Nanocomposite Manufacturing

Phase I program showed feasibility of the reactive nanocomposite materials as burn rate modifiers for aluminized propellants. The compatibility of nanocomposite materials with propellant components was established. The increases in burning efficiency and burning rate of aluminum were achieved. Aluminum agglomeration was alleviated and the practically achieved energy density of propellants was increased. The pressure exponent was reduced as a result of a higher achieved burn rate and better combustion efficiency. The current results are based on laboratory evaluations including window bomb and strand burner studies. The proposed Phase II program includes performance testing in the rocket motor configuration. The work will be aimed to identify specific propellant applications for which the proposed burn rate modifiers can be developed in a shortest time; develop a scalable manufacturing process of nanocomposites which does not include handling of sensitive materials; optimize and tailor properties and compositions of the produced nanocomposite powders according to the identified application; and prepare and provide to industry partner sufficient amounts of materials for incorporating into propellant formulations and safety evaluations. Six nanocomposite modifier compositions will be selected and evaluated in 1-lb propellant mixtures. One nanocomposite composition will be downselected for tests in different scale laboratory rocket motors.

Keywords:
Aluminized Propellants, Aluminum Agglomeration, Burn Rate Modifiers, Nanocomposite Materials, Thermites, Metal Combustion, Nanocomposite Manufacturing