Ruiqi Shen

Characterization of Al/CuO nanoenergetic multilayer films integrated with semiconductor bridge for initiator applications

This paper describes the ignition characteristics of Al/CuO nanoenergetic multilayer films (nEMFs) integrated with semiconductor bridge (SCB). The as-deposited Al/CuO nEMFs were identified with SEM and differential scanning calorimetry. Results show that distinct Al/CuO nEMFs are sputter deposited in a layered geometry, and the Al/CuO nEMFs gives a reaction heat equal to 2181 J/g. The firing experiments show that Al/CuO nEMFs have no influence on the electrical properties of SCB. Furthermore, the rapid combustion of Al/CuO nEMFs is able to assist SCB generating high-temperature plasma and products, such that enhance the ignition reliability.

Energetic semiconductor bridge device incorporating Al/MoOx multilayer nanofilms and negative temperature coefficient thermistor chip

The design, fabrication, and characterization of an energetic semiconductor bridge device are presented. The device consists of a semiconductor bridge heating element, which has been selectively coated with Al/MoOx multilayer nanofilms to enhance ignition of a conventional pyrotechnics. Integrated negative temperature coefficient thermistor chip provides protection against electromagnetic and electrostatic discharge events. The device was specifically configured to allow ease of interconnection by wire bonds and silver-filled conductive epoxy. Extensive design validation testing was performed. The device has demonstrated low, predictable firing energy and insensitivity. Al/MoOx multilayer nanofilms have no distinct influence on the electrical properties of semiconductor bridge. Nanothermite reaction provides reliable ignition by being able to ignite across a gap.

Progress on Laser-Induced Decomposition of Explosives Investigated by Spectroscopic Methods

Abstract: In an effort to get detailed information and provide insight into the basic physical process and elementary chemical reaction involved in laser-induced reactions in explosives, different research methods, including laser-induced breakdown spectroscopy (LIBS), mass spectrometry (MS), Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible (UV-Vis) spectroscopy, X-ray photoelectron spectroscopy (XPS), fluorescence spectroscopy, electron paramagnetic resonance (EPR) spectroscopy, etc., have been used to investigate the laser-induced photodecomposition of explosives experimentally. These kinds of experiments based on interactions of explosives with a laser might provide a unique contribution to solve the complex problem of combustion and detonation of laser ignition. The review is concerned with studies on laser-induced decomposition of typical explosives (nitrate esters, aromatic nitro compounds, and nitramines).

Thermal analysis of sodium azide and its mixtures

The reactions of sodium azide and its mixtures have been studied by the DTA-TG method. The reaction is very fast, and releases large amounts of gas and quantities of heat. With the addition of catalysis materials, the decomposition temperature will be reduced.

Dissociation of Cyclotrimethylenetrinitramine Under 1064-nm Laser Irradiation Investigated by Time-of-Flight Mass Spectrometer

ABSTRACT Laser-induced dissociation pathways of cyclotrimethylenetrinitramine have been investigated with a focused laser of 1064 nm by use of a time-of-flight mass spectrometer. The ions produced from the cyclotrimethylenetrinitramine surface were detected and the mass spectra of both positive and negative ions were obtained. According to the possible distribution of the decomposition products, possible dissociation paths of cyclotrimethylenetrinitramine were proposed. The influence of the intensity and the delay time of the laser beam to the decomposition have also been studied. The results may possibly throw some light on our understanding of the reactions taking place in laser ignition.

Electro-explosion performance of KNO3-filled carbon nanotubes initiator

An energetic initiator was developed by integrating KNO3@CNTs nanoenergetic materials with a Cu thin-film microbridge realized onto a ceramic substrate. The electro-explosion performances, including the voltage and current properties, the electro-explosion time, and the explosive sensitivity, of the initiator under capacitor discharge were investigated. The process of electrical explosion was observed by highspeed photography. The explosive sensitivity was obtained by Bruceton method. The results show that the Cu thin-film microbridge and the KNO3@CNTs initiator conducted different electro-explosion behaviours. Compared with the Cu thin-film microbridge, the explosive input energy was lower and the output energy was higher. It indicated that the superior electric and thermal conductivities of the carbon nanotubes and the chemical reaction of the KNO3@CNTs nanoenergetic materials were beneficial for the miniaturization of electropyrotechnics.

Characteristic of energetic semiconductor bridge based on Al/MoOx energetic multilayer nanofilms with different modulation periods

Three types of energetic semiconductor bridges (ESCBs) through integrating different Al/MoOx energetic multilayer nanofilms on a semiconductor bridge have been investigated in this study. The relationships among the critical firing energy, critical firing time, total firing time, and ignition energy as well as the input energy utilization efficiency of these initiators were analyzed. The principal component analysis (PCA) was utilized in the experiments to evaluate the output energy magnitude based on the ignition duration, the maximum flame area, reaction ratio, and other parameters. The results obtained were as follows: (1) The critical firing energy is positively proportional to the modulation periods of nanofilms for the initiators discharged with identical voltage, while the total firing energy and the input energy utilization efficiency do not change significantly; (2) by using PCA, the composite score of the ESCB/50 nm, ESCB/150 nm, ESCB/1500 nm, and SCB is measured at 3.025, 0.250, −1.433, and −1....

Integrating micro-ignitors with Al/Bi2O3/graphene oxide composite energetic films to realize tunable ignition performance

The integration of composite energetic films (CEFs) with various types of initiators can effectively adjust their performance and represents potential applications in microscale energy-demanding systems. In this study, the Al/Bi2O3/graphene oxide (GO) CEFs were successfully integrated into copper micro-ignitors by electrophoretic deposition, a low-cost and time-saving method. The effects of the Al/Bi2O3/GO CEFs with different GO contents on exothermic performance and ignition properties of micro-ignitors were then systematically investigated in terms of heat release, activation energy, ignition duration, the maximum height of the ignition product, and ignition delay time. The results showed that the addition of GO promoted more heat releases and higher activation energies of Al/Bi2O3/GO CEFs. The addition of ≤3.5 wt. % GO prolonged the ignition duration from 450 μs to 950 μs and increased the maximum height of the ignition product from about 40 mm to 60 mm. However, the micro-ignitors with more than 3.5 wt. % GO cannot be ignited, which suggested that GO played a contradictory role in the ignition properties of micro-ignitors and the controlled GO content was a prerequisite for improved ignition performance. The ignition delay time gradually extended from 10.7 μs to 27.6 μs with increases in the GO contents of Al/Bi2O3 CEFs, revealing that an increase in the weight ratio of GO leads to lower ignition sensitivity of micro-ignitors.

A Highly Integrated Conjoined Single Shot Switch and Exploding Foil Initiator Chip Based on MEMS Technology

In this letter, a highly integrated conjoined device, single shot switch and an exploding foil initiator (S3-EFI) chip, was fabricated with microelectromechanical system scale fabrication methods. Photon Doppler velocimetry was utilized to characterize the behavior of the flyer at firing voltages ranging from 1.00 to 2.40 kV. Electrical characterizations were then performed on the chip to obtain some fundamental parameters, such as current and voltage, and a peak current of 1.73 kA was observed at 1.50 kV. Moreover, ultrafine hexanitrostilbene pellets were detonated over firing voltage range 1.80–1.40 kV. These results demonstrate the feasibility of the chip and pave the way to the non-lead high-voltage discharge circuit. To the best of our knowledge, this is the first time to integrate exploding foil initiator with a high-voltage switch.

Photodissociation of 2, 4, 6-trinitrotoluene with a Nd:YAG laser at 532nm

2, 4, 6-Trinitrotoluene (TNT) belongs to the group of aromatic nitro compounds which have extended use in industrial applications, in particular as explosives or additives to explosives. Understanding the initial step of laser induced decomposition of common explosives is important to the reliability and safety of laser initiators and firing systems. Lasers coupled with mass spectrometer find wide application in photochemical studies for identification of different ions formed due to photoexcitation/ionization of molecules by laser. In this paper, a pulsed Nd: YAG (15ns, 532nm) laser was used for ionizating the condensed TNT sample, and the ions produced in the ionization process were detected by a time of flight mass spectrometer (TOFMS). The influence of laser fluence and the delay time to the decomposition was also studied. According to the assignment of both positive and negative ions, possible laser induced dissociation pathways were proposed. The results may tell much about the initiation process and the chemical reaction that may occur in TNT when exposed to laser pulse.