Study Of MEMS Energy Chip Based On In-situ Synthesis Of Three-dimensional Porous Micro-nano Structured Cu（N₃）₂

This article studied on the in-situ synthesis mechanism of three-dimensional(3-D) porous micro-nano structured copper azide (Cu(N3)2) and the main factors, influencing the target product, and preliminary designed and prepared MEMS energy chip based on the in-situ synthesis of three-dimensional porous micro-nano structured Cu(N3)2, meaningful results have been achieved.Copper azide (Cu(N3)2·CuN3) was synthesized through in situ reaction of porous copper (PCu) with hydrazoic acid(HN3) on 3-D foam PCu film (1cm×1cm) for 12h-48h. PCu was electrodeposited on copper sheet in a constant current density of 2A·cm-2 at room temperature for 30s. HN3 was prepared through the reaction of NaN3 and C17H35COOH at about 130℃, heating by collector magnetic stirrer, with slowly stirring.The reaction time played an important role in the reaction product. When the reaction time was 12h,24h,36h and 48h, the products were separately pure CuN3, mixture of Cu(N3)2-CuN3, mixture of Cu(N3)2·CuN3 and pure Cu(N3)2. It shows that PCu, reacting with HN3, firstly turns into CuN3, with time increasing, the reaction product becomes Cu(N3)2. It is pure Cu(N3)2 when the reaction time is about 48h.The valence of copper had an effect on the composition of reaction product. When the reaction time was 12h, the pure PCu turned into pure CuN3, but the partly oxidized PCu, including of CuO, Cu2O and Cu, became the mixture of Cu(N3)2-CuN3. It indicates that CuO is easier to become into Cu(N3)2 than pure Cu, reacting with HN3.Field emission scanning electron microscopy (FESEM) images show that the additives alter the morphology of PCu, however, copper azide possesses similar morphology as PCu. After the reaction of 24h, X-ray diffraction (XRD) analysis shows Cu(N3)2 is well crystallized orthorhombic structure, the preferable growth face of Cu(N3)2 is (110), and Cu(N3)2 at a length of about 200nm vertically scattered around the original copper dendrite. The thermal analysis shows the PCu deposited in electrolyte, consisting of NaCl and (NH4)2SO4, has the largest reaction degree in the same reaction condition. The wider crack in the wall of PCu and more rough surface of the prepared PCu, increase the contact area of PCu and HN3, then increase the degree of azide reaction.MEMS energy chip based on the in-situ synthesis of three-dimensional porous micro-nano structured Cu(N3)2 was preliminary designed and prepared. And it has been successfully triggered at 25V. The exploding phenomenon was monitored and recorded with a high speed camera (REDLAKE HG-100K) at a rate of 20000 fps. The whole process was fast and generates N2 and power rapidly when it was stimulated. The released gas can significantly enhance the explosive power, which is of great benefit to the applications.