A micro-initiator realized by in-situ synthesis of three-dimensional porous copper azide and its ignition performance

Abstract

Assembly of micro-initiator has received great attention on its application in micro-electromechanical systems, especially the integration between hazardous energetic materials and micro-ignitor. A micro-initiator was developed by integrating copper azide (Cu(N3)2·CuN3) nanoenergetic materials with a Ni-Cr microbridge realized onto a silicon substrate. In this work, three-dimensional (3-D) porous Cu (PCu) was prepared by electrochemical deposition with hydrogen bubble method. Copper azide has been synthesized through an in-situ reaction of hydrazoic acid (HN3) with three-dimensional (3-D) porous Cu (PCu), which facilitated integration between copper azide and microignitor. The novel materials were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetry-differential scanning calorimetry (TG/DTA) and an electric spark tester JGY-50III, respectively. The electrical explosion performances and electrostatic sensitivity of the micro-initiator were investigated by high-speed photography and electrostatic sensitivity tester. SEM images show the additives in the electrolyte alter the morphology of PCu, however, copper azide possesses similar morphology. The effect of copper valence and reaction time on azide reaction were evaluated. The discharge energy at 50% of novel copper azide was 0.098mJ. XRD analyses show the oxidization of PCu and the growth of the reaction time benefit the generation of cupric azide (Cu(N3)2) in the azide reaction. Furthermore, the discharge energy at 50% of novel micro-initiator was 64mJ. The novel material is environmentally friendly and can be successfully ignited by the Ni-Cr microbridge, exhibiting a significant improvement in micro-initiator application and realizing integrated fabrication of micro electro mechanical system (MEMS).