To reduce the size inconvenience of airbag systems employed in human-body protection devices while maintaining comparable gas generation performance, a new family of gas-generating energetic composites are proposed mixing Al/CuO nanothermite with copper complex (Cu(NH3)4(NO3)2) known for its propensity to generate gases (0.03 mol/g) such as N 2 , O 2 , N 2 O through exothermic chemical decomposition (300 J/g). The aluminum (Al)/Copper oxide (CuO) couple, known as the most widely studied nanomaterial for thermite reactions, releasing a high energy, mostly heat, through chemical reaction, is employed as a source of heat to trigger and sustain the decomposition of Cu(NH3)4(NO3)2 complex. This work permits developing a new family of gasgenerating energetic composites that takes advantage of specific chemical and thermal properties of both materials. We demonstrate its capability to tune the pressurization rate, burn rate and pressure peak by varying the Al/CuO over Cu(NH3)(NO2)2 mass ratio. The peak pressure of Cu(NH3)4(NO3)2/Al/CuO energetic composites reaches 12 MPa/g.cm 3 in a close volume, which is 3.3
A prior investigation by the authors demonstrated that incorporating 25% of copper complex (Cu(NH3)4(NO3)2) into Al/CuO nanothermite enables to produce highly-reactive gasgenerating energetic composites for emerging micro-airbag applications. To further improve the decomposition of the copper complex into gaseous species (N2, O2, N2O), during the thermite reaction, we employed ball milling technique to diminish its grain size down to the nanoscale. Results show that premilling the copper complex i.e. refining its grains without much modifying their structures, increases the pressure generation and burn rate by a factor 1.5 and 2, respectively. It also maintains a high degree of performances along a wider range of thermite to copper complex mass ratio.
A mixture of copper complex and Al/CuO nanothermite, Al/CuO/CuC, represents one state-ofthe-art gas-generating thermite systems with various pyrotechnic applications with respect to their tunable gas release rates. The reactivity of reactive inks with various loading of polyvinylpyrrolidone (PVP) binder mixed with Al/CuO/CuC is characterized using high-speed imaging diagnostics and pressure measurement. For a PVP mass fraction < 7 wt%, the printed materials remain highly reactive and burn at a high velocity (10 -54 m/s) which was one of the important goals in this study. At higher PVP content, the polymer inhibits the reaction. Printing (dropwise and continuously writing) of inks containing 5 wt% of PVP and 95 wt% of reactive Al/CuO/CuC powder was demonstrated using volumetrically controlled dispenser and pneumatically actuated syringe. The pressure development and burning rates of the printed materials are 0.37 MPa (at 46.3% TMD) and 17 m/s (at 0.24% TMD), more than a 10 times faster than the majority of works dealing with printed energetic formulations.
We developed an Ultimate Security Device (USD) that can, in case of intrusion or external attack, blow up a safetycritical component such as memory device. The device consists of two active parts (1) a pyroMEMS ignites in a fraction of millisecond (2) a mass of reactive composite, both encapsulated into a printed hermetic cap and placed over the sensitive component to be protected. After the presentation of the design and integration of the USD, we demonstrated that 400 mg of reactive composite permits to irreversibly destroy the silicon chips (~118 mm 3 ) in less than 10 ms. This ultimate security device provides a speedy and automatic response and can be programmed for tunable actions (generation of pressure burst, heat, chemical species) to implement relevant emergency safety responses.
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