279655 Water Processed Nanothermite Inks for Direct Deposition On Low Energy Initiators

Thursday, November 1, 2012: 5:20 PM
Frick (Omni )
Robert R. Nellums1, Steven F. Son2, Richard M. Kellett3, Craig J. Boucher3 and Lori J. Groven2, (1)Mechanical Engineering, Purdue University, West Lafayette, IN, (2)School of Mechanical Engineering, Purdue University, West Lafayette, IN, (3)Ensign-Bickford Aerospace and Defense

Pyrotechnic initiators are used in a multitude of applications spanning from airbag inflation systems to energetic detonators.  Specifically, semiconductor bridge (SCB) initiators have seen increased use in recent years, particularly in low energy devices.  Applications requiring SCB's with dimensions of 80 μm or smaller have sparked interest in the use of nano-sized energetics due to increased interfacial contact area between energetic particles and the bridge.  Previous work in this area showed that nanothermites, such as Al-Bi2O3, Al-MoO3, etc., work well for small initiators, but their application typically involves hazardous organic solvents.  While water processing has been suggested as an alternative to organic solvents, it has several drawbacks including material degradation, dangerous heating due to reaction of nano-sized aluminum with water, and difficulties in particle dispersion.  Currently, ammonium dihydrogen phosphate (ADP) is used to inhibit material degradation and subsequent reaction-induced heating in water processed nanothermites.  However, it was found that at the solids loading levels necessary for syringe deposition of nanothermite mixtures, safe processing was not possible with ADP.  This work reports a methodology in which the use of a palmatic acid coated nanoaluminum (L-ALEX) and an appropriate dispersant overcomes the above issues. By processing these nanoenergetic mixtures via a LabRAM Resodyn, a high solids loaded ink (30% v/v) results that can be directly applied to the bridge with no visible settling of reactants or cracks.  SCB ignition thresholds for these mixtures were found to be comparable to mixtures in which the mixing medium was dimethylformamide (DMF) (35 mJ*m-2 vs. 32 mJ*m-2).  This new processing technique allows for safer processing of sensitive nanoenergetics at high viscosities and has been shown to deliver reliable performance at low energy thresholds for SCB initiators.

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See more of this Session: Nanoenergetic Materials III
See more of this Group/Topical: Particle Technology Forum