Conventional exploding foil initiator (EFI) in ignition or detonation applications hosts many performance advantages, but was hindered by the bulky, inaccurate, inefficient and expensive shortcomings. We highlight a n...Conventional exploding foil initiator (EFI) in ignition or detonation applications hosts many performance advantages, but was hindered by the bulky, inaccurate, inefficient and expensive shortcomings. We highlight a novel micro-chip exploding foil initiator (McEFI) using printed circuit board (PCB) technology. The structural parameters were determined based on energy coupling relationship at the component interfaces. Next, the prototype McEFI has been batch-fabricated using PCB technology, with a monolithic structure of 7.0 mm (l) × 4.5 mm (w) × 4.0 mm (δ). As expected, this PCB-McEFI illustrated the successful firing validations for explosives pellets. This paper has addressed the cost problem in both military munitions and civil markets wherever reliable, insensitive and timing-dependent ignition or detonation are involved.展开更多
The storage stability of energetic materials is important for its application. Here, the storage stability of Al/CuO nanothermite, which was prepared by electrospray method and stored with different storage time, was ...The storage stability of energetic materials is important for its application. Here, the storage stability of Al/CuO nanothermite, which was prepared by electrospray method and stored with different storage time, was systematically researched. The activation energy of Al/CuO nanothermite was calculated by differential scanning calorimetry(DSC). The ignition temperature and the curve pressure history of Al/Cu O nanothermite was measured using ignition temperature measuring device and constant-volume pressurization tests, respectively. Further, the thermites were characterized by X-ray Diffractometer(XRD), X-ray photoelectron spectroscopy(XPS), scanning electron microscope(SEM) and Transmission electron microscopy(TEM). The results show that the morphology of the thermites did not change significantly. The activation energy was decreased from 254.1 k J/mol to 181.8 k J/mol after storage for 13 months. When stored for 0, 7 and 13 months, the peak pressures of Al/CuO nanothermite were 685.8 k Pa,626.3 k Pa and 625.5 k Pa, respectively. In addition to the ignition temperature, it was 775 ℃, 739 ℃ and754 ℃, respectively. This result indicated that the ignition and combustion properties of Al/CuO nanothermite are obviously reduced when stored for a long time, at room temperature.展开更多
Triggered spark-gap switch is a popular discharge switch for pulse power systems.Previous studies have focused on planarizing this switch using thin film techniques in order to meet the requirements of compact size in...Triggered spark-gap switch is a popular discharge switch for pulse power systems.Previous studies have focused on planarizing this switch using thin film techniques in order to meet the requirements of compact size in the systems.Such switches are one-shot due to electrodes being too thin to sufficiently resist spark-erosion.Additionally,these switches did not employ any structures in securing internal gas composition,resulting in inconsistent performance under harsh atmospheres.In this work,a novel planar triggered spark-gap switch(PTS)with a hermetically sealed cavity was batched-prepared with printed circuit board(PCB)technology,to achieve reusability with low cost.The proposed PTS was inspected by micro-computed tomography to ensure PCB techniques meet the requirements of machining precision.The results from electrical experiments demonstrated that PCB PTS were consistent and reusable with lifespan over 20 times.The calculated switch voltage and circuit current were consistent with those derived from real-world measurements.Finally,PCB PTS was used to introduce hexanitrostilbene(HNS)pellets in a pulse power system to verify its performance.展开更多
In this study,AleCuO nanocomposites were fabricated by sol-gel method.As a contrast,the thermite was prepared by physical mixing at the equivalence ratio of 0.5,1,2,respectively.The intermediates and samples as prepar...In this study,AleCuO nanocomposites were fabricated by sol-gel method.As a contrast,the thermite was prepared by physical mixing at the equivalence ratio of 0.5,1,2,respectively.The intermediates and samples as prepared were characterized by SEM and XRD.The exothermic properties of the two samples prepared at different equivalence ratios were tested and the reaction products were characterized by XRD.The SEM results show that the sample prepared by the sol-gel method demonstrates a micron-sized agglomerated sphere formed by a mutual wrapping of Al NPs and CuO NPs,and the particles are evenly distributed in the agglomerate.In addition,when the content of Al powder is seriously insufficient,the heat release of the sample prepared by physical mixing is 1.6 times that of by sol-gel method.With the increase of Al powder content,the exothermic properties of Al/CuO NPs prepared by sol-gel method began to increase significantly compared with physical mixing and the difference is 1.5 times when the equivalence ratio increases to 2.It can be concluded that the reason for this result may be attributed to the different mass transfer modes of components due to the different morphologies of samples.展开更多
Microsatellites have been widely applied in the fields of communication,remote sensing,navigation and science exploration due to its characteristics of low cost,flexible launch mode and short development period.Howeve...Microsatellites have been widely applied in the fields of communication,remote sensing,navigation and science exploration due to its characteristics of low cost,flexible launch mode and short development period.However,conventional solid-propellant have difficulties in starting and interrupting combustion because combustion is autonomously sustained after ignition Herein,we proposed a new type of solid-propellant named laser-controlled solid propellant,which is sensitive to laser irradiation and can be started or interrupted by switching on/off the continuous wave laser.To demonstrate the feasibility and investigate the controllable combustion behaviors under different laser on/off conditions,the combus tion parameters including burning rate,ignition delay time and platform pressure were tested using pressure sensor,high-speed camera and thermographic camera.The results showed that the increase of laser-on or laser-off duration both will lead to the decrease of propellant combustion performance during re-ignition and re-combustion process.This is mainly attributed to the laser attenuation caused by the accumulation of combustion residue and the change of chamber ambient temperature.Simultaneously the multiple ignition tests revealed that the increased chamber ambient temperature after combustion can make up for the energy loss of laser attenuation and expansion of chamber cavity.However,the laser-controlled combustion performance of solid propellant displayed a decrease trend with the addi-tion of ignition times.Nevertheless,the results still exchibited good laser-controlled agility of laser-controlled solid propellant and manifested its inspiring potential in many aspects of space missions.展开更多
Copper azide(CA), as a primary explosive with high energy density, has not been practically used so far because of its high electrostatic sensitivity. The Cu2O@HKUST-1 core-shell structure hybrid material was synthesi...Copper azide(CA), as a primary explosive with high energy density, has not been practically used so far because of its high electrostatic sensitivity. The Cu2O@HKUST-1 core-shell structure hybrid material was synthesized by the “bottle around ship” methodology in this research by regulating the dissolution rate of Cu2O and the generation rate of metal-organic framework(MOF) materials. Cu2O@HKUST-1 was carbonized to form a Cu O@porous carbon(CuO@PC) composite material. CuO@PC was synthesized into a copper azide(CA) @PC composite energetic material through a gas-solid phase in-situ azidation reaction.CA is encapsulated in PC framework, which acts as a nanoscale Faraday cage, and its excellent electrical conductivity prevents electrostatic charges from accumulating on the energetic material’s surface. The CA@PC composite energetic material has a CA content of 89.6%, and its electrostatic safety is nearly 30times that of pure CA(1.47 mJ compared to 0.05 mJ). CA@PC delivers an outstanding balance of safety and energy density compared to similar materials.展开更多
As an innovative propulsion technique, combustion mechanism of laser-augmented chemical propulsion has still to be ascertained. Benefiting from high nitrogen content and thermal stability, 5-aminotetrazole is a suitab...As an innovative propulsion technique, combustion mechanism of laser-augmented chemical propulsion has still to be ascertained. Benefiting from high nitrogen content and thermal stability, 5-aminotetrazole is a suitable ingredient for LACP. Under a flowing nitrogen environment, two kinds of unique burning surfaces were observed to occur for 5-ATZ, used as a single reacting propellant ingredient with the addition of carbon, under laser ablation. Both surfaces are hollow structures and differ by the possible presence of edges. Using micro computed tomography, the 3D perspective structures of both surfaces were revealed. Resorting to various characterization methods, a unified formation mechanism for both surfaces is proposed. This mechanism specifically applies to laser ablation, but could be crucial to common burning mechanisms in LACP.展开更多
The core-shell metastable intermolecular composites(MIC)have attracted much attention in the past few years due to their unique properties.Here,the preparation of Al-Core heterojunction fibers using PVP as a template ...The core-shell metastable intermolecular composites(MIC)have attracted much attention in the past few years due to their unique properties.Here,the preparation of Al-Core heterojunction fibers using PVP as a template is proposed.The nano-Al was directly added to the precursor solution of cupric acetate monohydrate(CAM)/Polyvinylpyrrolidone(PVP),and the initial Al@CAM/PVP fibers were obtained via electrospinning.The core-shell MIC fibers are then obtained by calcining the initial fibers.The morphology,structure,and composition of Al-core MIC fibers were characterized,that the energetic fibers calcined at 300℃,350℃,and 400℃have a core-shell structure with shell compositions CuxO and PVP,CuxO and Cu O,respectively.The energy release characteristics of Al-core MIC were investigated,and preliminary ignition tests were performed using an ignition temperature measuring instrument and a pulsed laser.The energetic fibers calcined at 300℃exhibited unique properties.The decomposition of PVP in the shell layer promoted exotherm,and a low-temperature exothermic peak was shown at 372-458℃.Lower ignition temperatures and higher flame heights were observed in the combustion tests than calcination at 350℃and 400℃.An unexpected result was that PVP can play a positive role in Al/CuO nanothermites.Simultaneously,this preparation method provided an idea for the integrated preparation of core-shell Al-Core MIC fibers and tuning the properties of MIC.展开更多
基金We gratefully acknowledge the support from National Natural Science Foundation of China(Grant No.22075145).
文摘Conventional exploding foil initiator (EFI) in ignition or detonation applications hosts many performance advantages, but was hindered by the bulky, inaccurate, inefficient and expensive shortcomings. We highlight a novel micro-chip exploding foil initiator (McEFI) using printed circuit board (PCB) technology. The structural parameters were determined based on energy coupling relationship at the component interfaces. Next, the prototype McEFI has been batch-fabricated using PCB technology, with a monolithic structure of 7.0 mm (l) × 4.5 mm (w) × 4.0 mm (δ). As expected, this PCB-McEFI illustrated the successful firing validations for explosives pellets. This paper has addressed the cost problem in both military munitions and civil markets wherever reliable, insensitive and timing-dependent ignition or detonation are involved.
文摘The storage stability of energetic materials is important for its application. Here, the storage stability of Al/CuO nanothermite, which was prepared by electrospray method and stored with different storage time, was systematically researched. The activation energy of Al/CuO nanothermite was calculated by differential scanning calorimetry(DSC). The ignition temperature and the curve pressure history of Al/Cu O nanothermite was measured using ignition temperature measuring device and constant-volume pressurization tests, respectively. Further, the thermites were characterized by X-ray Diffractometer(XRD), X-ray photoelectron spectroscopy(XPS), scanning electron microscope(SEM) and Transmission electron microscopy(TEM). The results show that the morphology of the thermites did not change significantly. The activation energy was decreased from 254.1 k J/mol to 181.8 k J/mol after storage for 13 months. When stored for 0, 7 and 13 months, the peak pressures of Al/CuO nanothermite were 685.8 k Pa,626.3 k Pa and 625.5 k Pa, respectively. In addition to the ignition temperature, it was 775 ℃, 739 ℃ and754 ℃, respectively. This result indicated that the ignition and combustion properties of Al/CuO nanothermite are obviously reduced when stored for a long time, at room temperature.
基金We gratefully acknowledge support from the Natural Science Foundation of Jiangsu Province of China(Grant No.BK20151486).
文摘Triggered spark-gap switch is a popular discharge switch for pulse power systems.Previous studies have focused on planarizing this switch using thin film techniques in order to meet the requirements of compact size in the systems.Such switches are one-shot due to electrodes being too thin to sufficiently resist spark-erosion.Additionally,these switches did not employ any structures in securing internal gas composition,resulting in inconsistent performance under harsh atmospheres.In this work,a novel planar triggered spark-gap switch(PTS)with a hermetically sealed cavity was batched-prepared with printed circuit board(PCB)technology,to achieve reusability with low cost.The proposed PTS was inspected by micro-computed tomography to ensure PCB techniques meet the requirements of machining precision.The results from electrical experiments demonstrated that PCB PTS were consistent and reusable with lifespan over 20 times.The calculated switch voltage and circuit current were consistent with those derived from real-world measurements.Finally,PCB PTS was used to introduce hexanitrostilbene(HNS)pellets in a pulse power system to verify its performance.
文摘In this study,AleCuO nanocomposites were fabricated by sol-gel method.As a contrast,the thermite was prepared by physical mixing at the equivalence ratio of 0.5,1,2,respectively.The intermediates and samples as prepared were characterized by SEM and XRD.The exothermic properties of the two samples prepared at different equivalence ratios were tested and the reaction products were characterized by XRD.The SEM results show that the sample prepared by the sol-gel method demonstrates a micron-sized agglomerated sphere formed by a mutual wrapping of Al NPs and CuO NPs,and the particles are evenly distributed in the agglomerate.In addition,when the content of Al powder is seriously insufficient,the heat release of the sample prepared by physical mixing is 1.6 times that of by sol-gel method.With the increase of Al powder content,the exothermic properties of Al/CuO NPs prepared by sol-gel method began to increase significantly compared with physical mixing and the difference is 1.5 times when the equivalence ratio increases to 2.It can be concluded that the reason for this result may be attributed to the different mass transfer modes of components due to the different morphologies of samples.
基金This work was supported by the Shanghai Aerospace Science&Technology Innovation Fund[grant number SAST201363],and the Fundamental Research Funds for the Central Universities[grant number 30919012102 in part]We gratefully acknowledge the technical support provided by Hao-yu Wang,Wei-kang Chen and Zhi-jing Xu(Shanghai Space Propulsion Technology Research Institute,China).
文摘Microsatellites have been widely applied in the fields of communication,remote sensing,navigation and science exploration due to its characteristics of low cost,flexible launch mode and short development period.However,conventional solid-propellant have difficulties in starting and interrupting combustion because combustion is autonomously sustained after ignition Herein,we proposed a new type of solid-propellant named laser-controlled solid propellant,which is sensitive to laser irradiation and can be started or interrupted by switching on/off the continuous wave laser.To demonstrate the feasibility and investigate the controllable combustion behaviors under different laser on/off conditions,the combus tion parameters including burning rate,ignition delay time and platform pressure were tested using pressure sensor,high-speed camera and thermographic camera.The results showed that the increase of laser-on or laser-off duration both will lead to the decrease of propellant combustion performance during re-ignition and re-combustion process.This is mainly attributed to the laser attenuation caused by the accumulation of combustion residue and the change of chamber ambient temperature.Simultaneously the multiple ignition tests revealed that the increased chamber ambient temperature after combustion can make up for the energy loss of laser attenuation and expansion of chamber cavity.However,the laser-controlled combustion performance of solid propellant displayed a decrease trend with the addi-tion of ignition times.Nevertheless,the results still exchibited good laser-controlled agility of laser-controlled solid propellant and manifested its inspiring potential in many aspects of space missions.
基金the financial support by Postgraduate Research & Practice Innovation Program from Jiangsu Science and Technology Department under Grant number KYCX19_0320。
文摘Copper azide(CA), as a primary explosive with high energy density, has not been practically used so far because of its high electrostatic sensitivity. The Cu2O@HKUST-1 core-shell structure hybrid material was synthesized by the “bottle around ship” methodology in this research by regulating the dissolution rate of Cu2O and the generation rate of metal-organic framework(MOF) materials. Cu2O@HKUST-1 was carbonized to form a Cu O@porous carbon(CuO@PC) composite material. CuO@PC was synthesized into a copper azide(CA) @PC composite energetic material through a gas-solid phase in-situ azidation reaction.CA is encapsulated in PC framework, which acts as a nanoscale Faraday cage, and its excellent electrical conductivity prevents electrostatic charges from accumulating on the energetic material’s surface. The CA@PC composite energetic material has a CA content of 89.6%, and its electrostatic safety is nearly 30times that of pure CA(1.47 mJ compared to 0.05 mJ). CA@PC delivers an outstanding balance of safety and energy density compared to similar materials.
基金supported by the Shanghai Aerospace Science & Technology Innovation Fund (Grant No. SAST201363)the Fundamental Research Funds for the Central Universities (Grant No. 30919012102 in part)。
文摘As an innovative propulsion technique, combustion mechanism of laser-augmented chemical propulsion has still to be ascertained. Benefiting from high nitrogen content and thermal stability, 5-aminotetrazole is a suitable ingredient for LACP. Under a flowing nitrogen environment, two kinds of unique burning surfaces were observed to occur for 5-ATZ, used as a single reacting propellant ingredient with the addition of carbon, under laser ablation. Both surfaces are hollow structures and differ by the possible presence of edges. Using micro computed tomography, the 3D perspective structures of both surfaces were revealed. Resorting to various characterization methods, a unified formation mechanism for both surfaces is proposed. This mechanism specifically applies to laser ablation, but could be crucial to common burning mechanisms in LACP.
文摘The core-shell metastable intermolecular composites(MIC)have attracted much attention in the past few years due to their unique properties.Here,the preparation of Al-Core heterojunction fibers using PVP as a template is proposed.The nano-Al was directly added to the precursor solution of cupric acetate monohydrate(CAM)/Polyvinylpyrrolidone(PVP),and the initial Al@CAM/PVP fibers were obtained via electrospinning.The core-shell MIC fibers are then obtained by calcining the initial fibers.The morphology,structure,and composition of Al-core MIC fibers were characterized,that the energetic fibers calcined at 300℃,350℃,and 400℃have a core-shell structure with shell compositions CuxO and PVP,CuxO and Cu O,respectively.The energy release characteristics of Al-core MIC were investigated,and preliminary ignition tests were performed using an ignition temperature measuring instrument and a pulsed laser.The energetic fibers calcined at 300℃exhibited unique properties.The decomposition of PVP in the shell layer promoted exotherm,and a low-temperature exothermic peak was shown at 372-458℃.Lower ignition temperatures and higher flame heights were observed in the combustion tests than calcination at 350℃and 400℃.An unexpected result was that PVP can play a positive role in Al/CuO nanothermites.Simultaneously,this preparation method provided an idea for the integrated preparation of core-shell Al-Core MIC fibers and tuning the properties of MIC.
