强流脉冲真空电弧镀膜技术

本文介绍一种新型镀膜工艺。该工艺是利用在真空环境下,两金属电极之间的亚秒级脉冲电弧放电产生的金属蒸发物来实现镀膜的。据报道可以镀各种金属和合金膜。     

真空电弧镀膜新技术

真空电弧镀膜在现代表面工程领域中作为一种新的高速沉积技术近年来得到了迅速发展并已开始进入工业应用。本文试就此新技术的原理、应用和发展前景作一简要介绍。     

中子管离子源高压脉冲电源

介绍了一种基于脉冲频率调制(Pulse Frequency Modulation,简称PFM)技术的数控高压脉冲电源.它利用PFM调制电路对输出电压进行调整和稳压,由单片机控制输出电压的脉宽,具有功耗低,体积小,重量轻,绝缘性能好等特点,而且输出高压在1.5～2.5kV连续可调.对具有高可靠性的过流保护电路进行了设计研究,在保证安全性的同时,满足了中子管性能检测系统中对离子源的供电需求.     

脉冲电弧侵蚀电极材料时的热分析

气体火花开关在大电流工作形下，会因为开关电极受到高能量，大电流电弧的烧蚀作用而影响其工作性能和寿命。本文根据电极电弧的烧蚀模型，通过热传导的计算，推导出了几个实用的公式，指出了选择耐烧蚀电极材料的原则和减少气体火花开关电极烧蚀的方法。     

大气压空气中纳秒脉冲介质阻挡放电均匀性的研究

为了实现大气压空气中纳秒脉冲均匀介质阻挡放电(DBD),利用上升沿15ns,半高宽30～40ns的正极性纳秒脉冲激发DBD,并由电压电流和放电图像研究DBD的特性,分析均匀放电实现的条件和特征。实验结果表明放电电流呈双极性,且电气参数要比交流及微秒脉冲DBD的高,在一定条件下可获得均匀模式放电。通过重复频率和气隙距离对放电均匀性的影响研究发现,2mm空气间隙中,双层介质阻挡时重复频率对放电均匀性影响不明显,但当间隙距离从2～8mm延长时,放电明显由均匀模式向丝状模式过渡。此外,对纳秒脉冲DBD放电均匀性与施加脉冲上升沿的关系进行了探讨。     

采样法原理电度表实现电能脉冲均匀化的处理方法

对采样法原理电度表的电能脉冲的产生方法及其均匀性进行了讨论,重点介绍了Ｄ－Ｆ变换原理和将其应用在采样法原理电度表中的特殊问题及为此而新研发的双重积分加平滑式Ｄ－Ｆ法。有杉该法可将电能脉冲的均匀度轻而易举地提高到优于０．０２５％,因此可方便地进行单脉冲校验。     

基于ARM的短电弧机床加工脉冲电源设计

短电弧加工机理研究要求电源输出低电压、大电流,输出频率及占空比可调且能实时采集电源各输出参数。针对上述要求,设计了一种基于ARM的短电弧机床数字化电源。该电源由脉冲电压电路和数字控制电路组成,脉冲电压电路提供所需脉冲电压,数字控制电路为脉冲电压电路提供控制及保护信号。并设计了一种调压控制电路,该电路具有调压范围广,稳压效果好等特性。实验结果证明了该电源满足对短电弧加工实验研究的需要,为短电弧加工机理研究提供了重要的技术支持。     

电弧反射电缆故障测距装置脉冲发射时刻选择算法

电弧反射法(ARM)是一种广泛应用的电缆故障测距方法.由于不清楚测试过程中电缆故障点电弧电阻的动态特性,因此施加测试脉冲时脉冲发射时刻的选择比较困难.分析了ARM测距装置放电过程中的电压和电流特性,以及故障点的电弧电阻特性.论证了在直流电弧放电阶段电弧电阻较低而且稳定,是发射脉冲的最佳时段.据此提出根据电流最大值和故障...     

脉冲激光沉积(PLD)法制备NiZn铁氧体多晶薄膜研究

采用脉冲激光沉积（PLD）法分别在硅和玻璃基片上沉积了NiZn铁氧体多晶薄膜。实验表明：基片温度、氧气压以及热处理对薄膜的沉积速率、磁性能有很大影响。     

电弧离子镀脉冲负偏压电源负载特性的仿真分析

通过等离子体物理理论和仿真分析 ,明确了电弧离子镀的等离子体负载本质是等离子体鞘层引起的容性负载 ,探讨了电弧离子镀脉冲负偏压电源的设计方法。     

Effect of Zr/Ti Ratio on Microstructure and Electrical Properties of Lead Zirconate Titanate Thin Films Derived by Pulsed Laser Deposition

PZT films were fabricated using various targets of Pb(Zr_xTi_{1 – x})O₃ with Zr/Ti ratios of 70/30, 58/42, 52/48, 45/55 and 30/70, and with excess PbO of 20 wt% on Pt/Ti/SiO₂/Si(100) substrates. The rosette structure was observed in the films derived from the target with a Zr/Ti ratio of 70/30 and disappeared with increasing titanium composition. The observations on surface and cross-sectional microstructure were consistent with a higher perovskite nucleation for the higher Ti content films. The PZT films derived from the target with a Zr/Ti ratio of 45/55 had a polycrystalline columnar microstructure extending throughout the thickness of the film and no pyrochlore phase on the surface was observed. The PZT films derived from the target with a Zr/Ti ratio of 45/55 exhibited better electric properties than those derived from the target with a Zr/Ti ratio of 52/48.     

Aging and Annealing Effects of ZnO Thin Films on GaAs Substrates Deposited by Pulsed Laser Deposition

Zinc oxide (ZnO) thin films were deposited on GaAs (100) substrates at different temperatures in the pulsed laser deposition (PLD) system. From the measurements of X-ray diffraction (XRD) at room temperature, 300–500°C were found to be good condition for the crystallization of the thin films. From the photoluminescence (PL) measurements, 500°C was found to be the optimized temperature for its optical property. Samples grown at 100, 200, 300, and 400°C showed near band-edge (NBE) emissions and deep-level emissions. The intensity of deep-level emissions decreased as time goes on, which is believed to originate from oxygen vacancies or zinc interstitials in thin films. While for the sample grown at 500°C, bright NBE emissions were observed at room temperature, and no deep-level emissions observed. This means that the high-optical-quality thin film was grown at 500°C. At the same time, annealing process of ZnO thin films grown at room temperature was carried out in PLD chamber. It was found that the annealing temperature of 600°C has strong effects on its PL. Aging and annealing effects in ZnO thin films grown on GaAs substrates by PLD were observed for the first time.     

A New Approach in Layer-by-layer Growth of Oxide Materials by Pulsed Laser Deposition

Pulsed laser deposition (PLD) has become thin film deposition technique with increasing prominence. One of the advantages above other techniques is the possibility to growth at relative high background pressures, with a large freedom in choosing the kind of gas. An example is oxygen in the case of high T_c superconductors and giant magnetic resistors. However, the advantage of relative high pressures hinders the use of a number of diagnostics and monitor techniques, like reflective high energy electron diffraction (RHEED). With the introduction of the possibility to use RHEED at standard PLD pressures, it became possible to study the growth of oxide materials under different oxygen and temperature conditions. In this paper we employed this technique on SrTiO₃, which can be grown in different growth modes depending on growth temperature and oxygen pressure during deposition. Applying a modified etch treatment on SrTiO₃ single crystals, a real 2D growth mode could be observed by the homo-epitaxial growth of SrTiO₃, as indicated by RHEED oscillations. In addition to the RHEED oscillations another phenomenon is observed, typical for PLD. The pulsed way of deposition leads to discontinuities in the intensity of the diffracted pattern. This is caused by the mobility of the deposited material from a disordered distribution till an ordered one and leads to a characteristic exponential slope with characteristic relaxation time constants. These time constants give extra information about relaxation, crystallization, and nucleation of the deposited material during growth. Finally, a new approach to deposit these complex oxide materials will be introduced. This, so-called interval deposition, is based upon the results obtained from the intensity oscillations as well as relaxations. The basic idea is to deposit an equivalent of one unit cell of material in such a short time that no coalescence in larger islands can occur, followed by a relaxation time before the next unit cell layer is deposited. This interval deposition leads to an imposed layer by layer growth.     

Studies of ZnO Thin Films On Sapphire (0001) Substrates Deposited by Pulsed Laser Deposition

ZnO thin films are deposited on sapphire (0001) substrates at different temperatures in the pulsed laser deposition (PLD) system. By measurements of X-ray diffraction (XRD), atomic force microscopy (AFM), and Photoluminescence (PL) at room temperature, fabrication temperatures higher than 400C is found to be the optimum condition for the structural and optical properties of ZnO thin films. With the increase of the fabrication temperature, the grain size becomes bigger and the thin film becomes more homogeneous. In order to get the high-quality ZnO thin film at low temperature, ZnO thin films are deposited at room temperature and annealed in a rapid thermal annealing (RTA) system. It is found that the optical property of the thin film can be greatly improved by annealing in RTA system.     

高压液相处理有机废水消弧触发开关的研制

为了满足高压脉冲液相放电废水处理技术需要,研制一套消弧触发放电开关装置,在绝缘转子的圆周上均布转动触头,与绝缘定子上的弹力触头,实现通-断接触,形成开关.当转速调到1000r/min时,脉冲频率为200Hz,装置运行平稳、触点通-断灵活、接触可靠;电压加载到40kV时,单触发开关旋转正常,未听到触点起弧的声音,高压脉冲在液相中放电正常,放电火花明亮、有力,实验证明是一款性能优良的触发开关     

Pulsed Laser Deposition of Ba0.6Sr0.4TiO3 Thin Films and Their Optical Properties

ABSTRACT

Barium strontium titanate [Ba_0.6Sr_0.4TiO₃ or BST (60/40)] thin films were deposited on MgO (100) substrates using pulsed laser deposition. X-ray diffraction (XRD) measurements revealed that the BST thin films had epitaxially grown on the MgO (100) substrates. The surface morphology of the thin films was observed using an atomic force microscope and the grain size was found to be about 100–150 nm. The surface roughness was around 4.9 nm for a 250 nm thick film. The optical transmittance of the BST thin film was measured using a transmission mode ellipsometer. The BST/MgO configuration was highly transparent in the visible region. The optical band gap energy of the BST film, calculated by applying the Tauc relation, was 3.56 eV. Optical waveguide characteristics of the BST (60/40) thin film were determined using a prism coupler. The electro-optic (E-O) properties were measured at 632.8 nm wavelength using a phase modulation detection method. The BST film exhibited a predominately quadratic E-O behavior and the quadratic E-O coefficient was found to be 0.58 × 10^{? 17} m²/V².     

热处理工艺对金属化膜脉冲电容器性能的影响

初步探讨了热处理工艺对金属化膜电容器性能的影响 ,并试制了一批试品 ,用以比较不同热处理温度对电容器性能及喷金与热处理工艺的先后次序对电容器性能的影响 ,给出了金属化膜电容器用于高场强领域的一些建议。     

脉冲电弧放电产生医用一氧化氮的放电条件研究

NO作为救治急性呼吸衰竭综合征的新方法而受到关注。空气中的电弧放电可以产生NO。为满足NO医疗应用对NO2和NO2/(NOx)尽可能小的要求,实验采用负脉冲电弧放电,重点研究了电极间距、放电频率和电极极性等参数对NO和NO2浓度的影响。结果发现:NO2/(NOx)的比值在某电极间距范围内有一个最低值,NO和NO2浓度随电极间距和放电频率的提高而增加,电极极性对NO2/NOx比值的影响不明显。可以通过对放电条件的选择与组合,达到降低NO2浓度和NO2/(NOx)比值的目的。