A nanoparticle formation model considering layered motion based on an electrical explosion experiment with AI wires

To study the evolution of nanoparticles during Al wire electrical explosion,a nanoparticle formation model that considered layered motion was developed,and an experimental system was set up to carry out electrical explosion experiments using 0.1 mm and 0.2 mm Al wires.The characteristic parameters and evolution process during the formation of nanoparticles were calculated and analyzed.The results show that the maximum velocities of the innermost and outermost layers are about 1200 m·s-1and 1600 m·s-1,and the velocity of the middle layer is about 1400 m·s-1,respectively.Most of the nanoparticles are formed in the temperature range of2600 K-2500 K.The characteristic temperature for the formation of Al nanoparticles is~2520K,which is also the characteristic temperature of other parameters.The size distribution range of the formed nanoparticles is 18 to 110 nm,and most of them are around 22 nm.The variation of saturated vapor pressure determines the temperature distribution range of particle nucleation.There is a minimum critical diameter of particles(~25 nm);particles smaller than the critical diameter can grow into larger particles during surface growth.Particle motion has an effect on the surface growth and aggregation process of particles,and also on the distribution area of larger-diameter particles.The simulation results are in good agreement with the experiments.We provide a method to estimate the size and distribution of nanoparticles,which is of great significance to understand the formation process of particles during the evolution of wire electrical explosion.

Nanopowder production by gas-embedded electrical explosion of wire

A small electrical explosion of wire （EEW） setup for nanopowder production is constructed. It consists of a low inductance capacitor bank of 2 μF–4 μF typically charged to 8 kV–30 kV, a triggered gas switch, and a production chamber housing the exploding wire load and ambient gas. With the EEW device, nanosize powders of titanium oxides, titanium nitrides, copper oxides, and zinc oxides are successfully synthesized. The average particle size of synthesized powders under different experimental conditions is in a range of 20nm–80nm. The pressure of ambient gas or wire vapor can strongly affect the average particle size. The lower the pressure, the smaller the particle size is. For wire material with relatively high resistivity, such as titanium, whose deposited energy Wd is often less than sublimation energy W s due to the flashover breakdown along the wire prematurely ending the Joule heating process, the synthesized particle size of titanium oxides or titanium nitrides increases with overheat coefficient k （k = W d /Ws ） increasing.

Numerical simulation of the initial plasma formation and current transfer in single-wire electrical explosion in vacuum

In this paper, a computational model is constructed to investigate the phenomenon of the initial plasma formation and current transfer in the single-wire electrical explosion in a vacuum. The process of the single-wire electrical explosion is divided into four stages. Stage Ⅰ： the wire is in solid state. Stage Ⅱ： the melting stage. Stage Ⅲ： the wire melts completely and the initial plasma forms. Stage IV： the core and corona expand separately. The thermodynamic calculation is applied before the wire melts completely in stages Ⅰ and Ⅱ. In stage Ⅲ, a one-dimensional magnetohydrodynamics model comes into play until the instant when the voltage collapse occurs. The temperature, density, and velocity, which are derived from the magnetohydrodynamics calculation, are averaged over the distribution area. The averaged parameters are taken as the initial conditions for stage Ⅳ in which a simplified magnetohydrodynamics model is applied. A wide-range semi-empirical equation of state, which is established based on the Thomas-Fermi-Kirzhnits model, is constructed to describe the phase transition from solid state to plasma state. The initial plasma formation and the phenomenon of current transfer in the electrical explosion of aluminum wire are investigated using the computational model. Experiments of electrical explosion of aluminum wires are carried out to verify this model. Simulation results are also compared with experimental results of the electrical explosion of copper wire.

Discharge and post-explosion behaviors of electrical explosion of conductors from a single wire to planar wire array

This work deals with an experimental study of a Cu planar wire array(PWA)in air and water under the stored energy 300-1200 J.A single Cu wire is adopted as a controlled trial.Four configurations of PWA and a wire with the same mass(cross-section area)but the different specific surface areas(15-223 cm^(2)g^(-1))are exploded.The transient process is analyzed using high-speed photography in combination with the results of optical emission and discharge.Discharge characteristics revealed that PWA always has a higher electric power peak,early but higher voltage peak,as well as faster vaporization and ionization process than the single-wire case.Two to three times stronger optical emission could be obtained when replacing the single-wire with PWA,indicating a higher energy-density state is reached.Phenomenologically,in both air and water,single-wire load tends to develop a transverse stratified structure,while PWA is dominated by the uneven energy deposition among wires.Finally,the synchronism and uniformity of the PWA explosion are discussed.

One-step synthesis of FeO(OH)nanoparticles by electric explosion of iron wire underwater

In this study,we investigated electric explosion of iron wire in distilled water with different energy input adjusted by charging voltage.The as-prepared samples were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM)and X-ray photoelectron spectroscopy(XPS),showing the presence of iron and multiple iron-based compounds oxides with contents influenced by the experimental conditions.In particular,pure FeO(OH)nanoparticles were obtained using electric explosion of iron wire with energy input of 1125 J at charging voltage of 15 kV.Analysis of discharge current and resistive voltage data indicate that the high energy input induced bystrong plasma discharge at high charging voltage is a key factor to form FeO(OH).This study presents a one-step method to synthesize FeO(OH)nanoparticles using electric explosion of iron wire.

Influence of current injection ways on efficiency and size of powders in preparation of nano-powders with electrical explosion

Wire electrical explosion may result in the existence of micro-sized large particles in powders while current injection ways may influence the size and content of micro-sized large particles. Therefore, two kinds of electrical explosion devices with different electrodes by gas discharge were designed in this paper. The pole-board electrodes and the cone electrodes were used respectively for studying copper wire electrical explosion process. The current and voltage data were measured with the Rogowski coil and high voltage probe. The results show that the pulverizing process of electrical explosion is more efficient when the wire electrode current density injected into the cone electrodes is approximately twice as much as the pole-board electrodes. The content of micro-sized large particles is the least among the products of the electrical explosion, when the total deposition energy of the wire prior to vaporization stage is 2. 5 times larger than that of the theoretical value of the completed vaporization.

丝电爆法制备3D打印金属钽粉的试验研究

针对微米球形钽粉难以制备、粒径不易控制等问题,论文利用丝电爆法成功制备了微米球形钽粉,通过改变初始充电电压、钽丝丝径进行试验,采集丝电爆过程的电压与电流信号,对其机理进行了分析,并表征了所制备的微米钽粉。结果表明:不同丝径下的丝电爆炸过程都经历了五个阶段,丝径为0.4mm钽丝在电爆炸过程中发生了完全气化,而丝径为0.2mm、0.3mm钽丝并未完全气化,处于气液混合的状态;随着初始充电电压的不断增大,一定丝径钽丝上的沉积能量会有不同程度的增加,所制备的微米球形钽粉的平均粒径在逐渐减小;在初始充电电压为10kV时,丝径为0.2mm钽丝所制备的钽粉集中分布在28μm~36μm之间,分布范围较窄,球形度良好,且满足微米级3D打印金属粉的粒径要求。

可控冲击波震源技术在陕北沙漠区地震勘探的应用

针对现有地震勘探震源存在问题和局限性,创新性地将金属丝电爆炸可控冲击波技术应用于地震勘探中,分析了金属丝电爆炸可控冲击波技术和产生原理。在掌握金属丝电爆炸可控冲击波技术作为地震勘探震源技术的特点和陕北沙漠地区进行现场激发试验的情况下,从理论分析和现场试验验证了金属丝电爆炸可控冲击波技术作为震源技术的可行性。通过对获取的数据进行定量分析,认为可控冲击波技术可作为一种新型震源技术,且在陕北沙漠区煤田地震勘探领域具备较好的应用发展前景。同时,通过总结试验中存在的问题,为下一步的改进提供方向。

Effect of the Circuit and Wire Parameters on Exploding an Al Wire in Water

The underwater electrical explosion of an aluminum wire is influenced by many factors, such as wire parameters, pulsed power energy, etc. In this paper, underwater electrical explosion of an aluminum wire was investigated with pulsed voltage in the time scale of a few microseconds. A self-integrated Rogowski coil and a voltage divider were used for the measurements of current and voltage at the wire load, respectively. The deposited energy before breakdown was calculated based on experimental waveforms of current and voltage by mathematical method. Effects of the applied voltage, circuit inductance and sion and energy deposition were analyzed by means parameters of Al wire on the electrical exploof experiments and calculation. The results show that the current rise rate has an important influence on explosion process, such as the energy deposition before breakdown, the electrical power as well as the various explosion stages. A higher current rise rate can be achieved by increasing applied voltage and decreasing circuit inductance. The inhomogeneity of the energy deposition will result in prematured breakdown as well as lowered energy deposition, making the explosion process of wire more complicated.

镍铁丝电爆炸特性及超细粉制备

利用非接触式丝电爆制粉装置制备了球形度良好、纯度高的镍铁超细粉,在氩气气氛中使用直径0.4 mm的镍铁丝在不同充电电压下进行实验,同步采集并分析镍铁丝电爆炸放电波形及沉积能量变化规律。建立了镍铁丝电爆炸过程中的时变非线性电阻模型,并与实验曲线进行对比分析;利用扫描电镜观察粉末形貌,分析镍铁丝电爆炸工艺参数对粉末形貌、粒径的影响。结果表明:随着充电电压的升高,放电波形及金属丝沉积能量峰值逐渐增大,沿面击穿时刻逐渐提前;在击穿前金属丝电阻模型与实验曲线符合程度良好;在充电电压为11~15 kV的工艺参数下,可制得球形度良好、粒径分布均匀且纯度较高的超细粉。

铝纳米粉末活化树突状细胞的作用

采用电爆炸法制备金属铝纳米粉末(ALEX),验证了其免疫增强效应及肿瘤预防效果.首先,利用铝金属丝电爆炸法,并应用羧基端基聚合物配体反应的方法合成了分散性良好的ALEX.利用静电物理吸附将抗原卵清蛋白(OVA)、抗原多肽(Peptide)接枝于ALEX表面,傅里叶变换红外光谱检测证明抗原与ALEX成功覆合.其次,验证了ALEX增强特异性免疫反应的效果.通过体外实验证明,ALEX可提高树突状细胞(DCs)的抗原提呈效果;同时,对免疫后小鼠血清抗体进行了定量检测,结果表明ALEX可显著提高小鼠体内抗原特异性抗体的水平.最后,利用小鼠黑色素瘤模型,验证了含有ALEX的肿瘤疫苗能够有效预防肿瘤的发生.

水中液态金属丝电爆炸特性

水中金属丝电爆炸可产生具有更高能量效率的冲击波,已在化石能源开发等领域取得成功应用。但是,金属丝电爆炸是在电极间预置金属丝,需要附加换丝机构,存在重频运行困难问题。该文提出一种基于镓铟锡液态金属的换丝方法,该方法利用液态金属自身的流动性,能够在低电压控制下快速、稳定地在放电电极间成丝。在相同的放电模式下改变电压完成多次放电,并测量放电过程中丝端电压、回路电流,计算回路参数以及能量;根据实验数据建立仿真模型,分析击穿时延击穿时刻电阻分别作为单一变量的能量转换特性。仿真与实验结果表明,镓铟锡液态金属丝放电相态变化过程与普通金属丝相比存在差异;电容初始充电电压越高,液态金属丝击穿时刻电阻越大,放电击穿时延越短,能量转换效率越高。该研究对水下液态金属丝放电特性的研究以及完善金属丝电爆炸技术在工业中的应用具有一定参考意义。

带载丝电爆炸提高沉积能量的研究

在丝电爆过程中,金属丝的沉积能量是决定爆炸效果的关键参数。在研发连续送丝电爆装置的基础上,提出带载丝电爆炸提高金属丝沉积能量的方法。根据金属丝在电爆过程中的相变理论及旁路并联电阻的非线性时变性,建立了金属丝负载的电阻-能量分段模型。使用带载丝和裸丝分别开展电爆炸实验,同步采集丝电爆过程中的放电波形并分析计算,探究带载丝电爆炸相关机理以及沉积能量的变化规律。结果表明,电爆炸前期,由于载丝带具有绝缘性,其旁路并联电阻大于裸丝,从而使得带载丝电阻大于裸丝;随着欧姆加热的进行,带载丝中液态金属沿轴向由两端向中间聚集,加快了电爆炸相变过程,等效电阻减小,延缓了沿面击穿过程,从而获得更多的能量。

微秒电脉冲驱动电爆炸等离子体光辐射特性研究进展

电爆炸等离子体的光辐射特性对探究非理想等离子体性质及含能材料点火技术具有重要意义。在过去几十年,国内外学者对电爆炸物理与效应开展了广泛研究,明确了等离子体及可见光辐射效应的典型特征规律。近年来,随着电爆炸技术在国防、能源和材料领域的逐步应用,人们开始关注电爆炸等离子体光辐射现象中更多的物理细节,以期实现电爆炸负载光辐射效应的有效调控。本文简要回顾了电爆炸负载及其光辐射效应的研究历程,并介绍了相关实验手段及技术原理。从动力学角度系统介绍了电爆炸等离子体及光辐射的时空演化行为,从光谱学角度分析了放电不同阶段的辐射光谱特性,建立了电爆炸关键过程和光辐射物理机制的对应性,归纳了放电模式、金属材质、介质类型对负载光辐射特性的影响。最后,探讨了基于强光辐射效应的电爆炸技术的发展趋势。

纯水和液氮中金属丝电爆炸与等离子体气泡特性实验研究

金属丝电爆炸能有效地将电能转化为机械能(冲击波和等离子体气泡),在化石能源开发等领域取得了成功应用。为明确不同液体中金属丝电爆炸等离子体气泡行为,搭建可变环境金属丝电爆炸实验平台与诊断系统,通过改变电容充电电压,获得不同储能下kA量级和μs时间尺度的脉冲电流,驱动直径为50μm的铜丝电爆炸。通过测量负载电压、回路电流以及拍摄高速阴影图像,对放电瞬态过程进行诊断和分析。结果表明:不同系统储能或负载规格下,液体中金属丝电爆炸存在非周期型放电、周期型放电以及电流暂停放电3种模式;与纯水(蒸馏水)介质相比,液氮中电爆炸具有更高的电压峰值(平均高约6%)、功率峰值(平均高约14%)。纯水中等离子体气泡脉动过程受系统储能和负载规格影响,系统储能从2 J增大至10 J时,气泡最大径向半径从约9.4 mm增大至约18.6 mm,第一脉动周期从约1.6 ms增长至约2.6 ms,气泡能量从约0.4 J增大至约2.3 J,气泡能量效率相对稳定,为18%~25%;相同储能下增加金属丝长度,最大径向半径逐渐缩短。储能2.5 J下,液氮气泡第一脉动周期比纯水中长约0.6 ms,最大径向半径约为纯水中气泡的1.17倍,在气泡收缩阶段,液氮气泡收缩速度慢,最小收缩半径约为纯水中气泡的1.53倍。

FeCr纳米合金粉的制备及性能

采用电爆炸法制备了FeCr纳米合金粉,对不同放电电压和金属丝丝径对粉体粒径及其分布的影响进行了探究。结果表明,在设备内压力、冷却温度等工艺参数不变的前提下,随着放电电压的增大、金属丝丝径的降低,纳米粉体粒径逐渐降低,粒径分布逐渐变窄。当放电电压为16 kV、金属丝直径为0.2 mm时,制得的FeCr纳米合金粉性能较好,粉体呈光滑球形,粒径大小基本处于100 nm以下,平均粒径仅为57.87 nm,其Fe、Cr、O含量与FeCr合金丝基本相同,物相结构主要为Fe-Cr合金相。

可控冲击波震源在地震勘探中的试验

近年来,国家对安全生产和环境保护的新要求越来越严格,尤其是炸药震源的使用限制条件越来越多。在安全生产形势严峻,火工品使用受限,现有的其他类型震源又无法满足地震勘探施工要求的区域,很大程度上限制了地震勘探方法的应用。可控冲击波技术是以脉冲功率技术为基础的新技术,该技术具有幅值和冲量可控,作业区域不受限制,可重复使用的特点。本文对可控冲击波技术及其发展历程进行简要介绍,并将现有可控冲击波设备改进后作为震源进行了激发地震波试验,对获取的地震资料进行定量分析,结果表明可控冲击波技术可以应用到地震勘探领域,同时提出了当前可控冲击波设备需要改进的技术问题。

电爆炸丝法制备纳米Al_2O_3粉末

设计了电爆炸金属丝产生纳米金属氧化物粉末的实验装置,金属丝电爆炸腔采用圆筒结构,纳米粉末经过微孔滤膜过滤收集。成功制备了纳米Al2O3粉末,其平均粒度达到64.9 nm。对电爆炸金属丝产生纳米Al2O3粉末的物理条件进行了研究。结果表明实验条件对粉末粒度有重要影响:随气压的增加粉末平均粒度变大;随金属丝直径增大粉末平均粒度变大;粉末的平均粒度与电容器的初始储能也有一定的关系。

电爆炸丝法产生nm粉末及负载型nm催化剂

为了探索电爆炸金属丝技术在制备纳米粉末及其相关产品中的应用前景,利用电爆炸金属丝法成功制备了平均粒度分别达到65 nm和44 nm的纳米Al2O3和TiO2粉末,通过X射线衍射和电子衍射分析,Al2O3粉末为γ-Al2O3,TiO2粉末由金红石和锐钛矿组成。研究了实验条件对产生粉末粒度的影响及其规律后探索了电爆炸丝法产生负载型纳米催化剂的实验条件,并成功制备了负载型纳米TiO2催化剂,其化学实验结果表明:与现有催化剂比较,该催化剂能使某类化学反应的速度提高>50%,反应产物的选择性提高>3%。

介质对铜丝电爆炸沉积能量的影响

铜丝在电爆炸过程中要经历固态、液态、气态和等离子体4种状态,而铜丝在电爆炸过程中吸收的能量全部来自于电流的焦耳热效应,爆炸时周围介质对爆炸过程有着显著的影响。为此对μs脉冲电压下空气和水介质中铜丝电爆炸进行了实验研究,利用自积分Rogowski线圈和电阻分压器分别测量铜丝电爆炸时的电流和电压。利用数学方法分别计算了铜丝熔融过程,液态以及汽化过程中沉积的能量。通过实验和计算,分析了空气和水介质对铜丝电爆炸的发展和各个过程中沉积能量的影响,得出介质密度是影响铜丝电爆炸过程沉积能量的重要因素。铜丝在水介质与空气介质中的电爆炸过程有着显著区别,水中铜丝电爆炸各过程的沉积能量较高,尤其在汽化开始之后更加显著。