故障连接器触点表面污染物的特征和成因的初步分析

在电子通信设备中,电接触故障是通信传输故障的重要原因.经检测,触点表面污染物是导致连接器电接触故障的主要原因之一.由于污染物在电流通过时呈现高电阻特性,当接触位于污染物上时,就可能会造成电接触故障.对于某失效连接器故障接触表面的SEM/XES分析表明,接触区的污染物数量远高于非接触区.接触区的污染物基本上连续地堆积在触点周围,非接触区的污染物多为散布的颗粒.接触区的污染物由尘土和金属磨损碎屑组成,有些污染物由微粒堆积而成.用扫描电子显微镜（SEM）和能谱仪（XES）对污染表面进行了显微观测和成分分析,统计出了表面污染物中的常见元素.根据检测结果可初步推测,触点表面对大气中尘土颗粒的吸附以及触点间的磨损是表面污染物形成的主要原因.     

KPFM导电探针的制备及应用

开尔文探针力显微镜(KPFM)可以测量样品与探针之间的接触电势差(CPD),从而可以测得样品表面电势.为了更好地测量样品表面电势的微小变化,需要制备新型导电探针.金属铱稳定的化学性质与高导电率等特性能够稳定地测量尖端样品之间的电势差.实验使用物理气相沉积(PVD)的方法修饰硅探针,使针尖镀上一层厚度为纳米级的金属铱薄膜...     

扁平连接器线束故障原因分析

针对扁平连接器线束故障中接触不良的问题,使用CT设备、金相显微镜以及扫描电子显微镜、模拟试验等设备与方法,对接触不良线束进行原因分析.结果表明:接触不良的直接原因为线束接触片出现裂纹或断裂导致,属于应力腐蚀开裂(SCC).连接器中的电子流动方向是造成奇偶数位接触片腐蚀状态差异的直接原因.镀镍黄铜表面微裂纹,使黄铜基材裸...     

承烧材料对MnZn铁氧体磁性能的影响

研究了莫来石承烧材料与底层磁芯之间的相互作用及其对MnZn铁氧体磁芯性能的影响。结果表明,受承烧材料影响,底层磁芯性能下降,其主要原因是Zn挥发引起的成分偏离。成分分析证实磁芯接触端面有Si4 渗透产生的侵蚀层(厚度约100μm);物相分析证实Al2O3与ZnO反应生成ZnAl2O4异相物质是Zn挥发的主要途径,两者同时作用导致材料性能严重恶化。     

基于隧道效应的纳米级振动检测及测量

扫描隧道显微镜是高精度纳米级表面测量仪器,由于扫描隧道显微镜工作时的隧道间隙在几个纳米左右,外界任何微小的随机振动传递到仪器都会对测量结果产生影响,失去被测物表面的特征信息.因此,研究微振动,特别是低频纳米级振动在隧道状态下对隧道间隙的影响具有很重要的意义.实验表明,实验系统在隧道状态下对纳米级振动有很好的幅频响应.     

Si/C负极在实际应用中的失效原因分析

将一种Si/C复合负极材料应用于14500圆柱形电池体系中,对它与碳负极电池的基本性能进行了对比,并对该种Si/C负极材料在实际应用中存在的问题以及失效原因进行了分析.以Si/C为负极的电池,其200次循环后容量维持率仅为69.5%.经分析表明,造成其容量衰减的主要原因为:电极体积膨胀导致电极活性材料脱落,电接触性能变差;由材料体积膨胀导致固体电解质相界面(SEI)膜被破坏而造成的电解液不断的分解,使正、负极界面膜增厚,电阻增加;材料本身结构造成插入的Li无法全部脱出.     

利用原子力显微镜探究污秽颗粒在绝缘子表面的粘附力

不同材料的绝缘子表面对污秽颗粒的粘附力不同,这是造成不同绝缘子之间积污差异性的重要原因之一。为了研究不同绝缘子对污秽颗粒的粘附力,利用原子力显微镜测量了单个污秽颗粒在不同材料(普通玻璃、硅橡胶、瓷、钢化玻璃)表面的粘附力。结果表明:粘附力的大小与材料性质、表面粗糙度、表面荷电状态等因素有关;与瓷和钢化玻璃相比,硅橡胶对污秽颗粒表现出更大的粘附力。实际绝缘子在运行过程中表面有可能会产生电荷积聚,因此进一步研究了绝缘材料表面荷电对粘附力的影响,得出结论:试片表面荷电会对污秽颗粒产生较强的长程吸引力作用,但是对粘附力的影响不显著。     

波动压力载荷下弓网滑动电接触特性研究

列车运行过程中的弓网压力载荷以类似正弦形式波动,波动载荷对弓网系统滑动电接触性能有显著影响。文中利用销盘式实验机模拟弓网系统接触圧力的波动状态,实验分析了在不同电流密度、运行速度的工况下,压力波动幅度和波动频率对弓网系统受流和磨损的影响机理。研究表明:压力载荷在波动状态下,压力波动幅度的增大和运行速度的增大都会导致载流效率降低和销试样的磨损率增大;电流密度的增大会导致磨损率增大和载流效率的先增后减;压力波动频率的变化对载流效率和销试样的磨损率影响不明显。电弧烧蚀和温度升高造成销表面粗糙是导致磨损率增大和载流效率降低的主要原因。压力波动幅度、运行速度和电流密度是影响弓网滑动电接触摩擦磨损和载流效率的主要因素。     

机械转换动作导致触点接触电阻明显增长

当银触点在大气（试验室环境）中,在没有负载切换电流条件下,实施机械的断开与闭合动作时,大约有四分之三的试验样品出现接触电阻明显的增大,使用俄歇仪（AES）在触点表面上未检测出污染生成物。但是扫描镜（SEM）却揭示了如下所述的接触电阻特性与触点表面状态间存在着颇为奇特的相互关系。接触电阻增加的样品具有镜面光滑的触点表面,而接触电阻低而稳定的样品却呈现出严重损伤的粗糙触点表面。接触电阻特性也显示出受到测量电流电平和触点压力大小的影响。利用这些试验结果并考虑到电极表面磨损类型的影响,来讨论这种现象的一种潜在的虚拟机理。     

等离子体射流阵列辅助薄膜沉积对环氧树脂表面电气特性的影响

直流电场下的绝缘材料表面电荷积聚现象对电气设备的安全运行造成威胁。为了加快环氧树脂(ER)表面电荷的消散,文中采用纳秒脉冲电源激励的大气压等离子体射流(APPJ)阵列,对环氧树脂表面进行扫描处理,沉积SiO_x薄膜,之后利用傅里叶变换红外光谱仪(FTIR)、扫描电子显微镜(SEM)、高阻计、表面电位测试系统等装置对改性前后的样品表面理化特性进行表征分析。实验结果表明:射流阵列扫描沉积在环氧树脂表面引入了Si—O—Si、Si—OH和OH等基团,并且形成的薄膜使材料表面粗糙度降低。改性后的环氧树脂表面电导率提升2~3个数量级,使表面电荷初始积聚量减少,消散速度加快,陷阱能级的深度与密度均有所降低,闪络电压由未处理时的-6.5 kV提升至扫描沉积4次时的-9.3 kV。相对于单管射流改性,射流阵列可产生更大面积的低温等离子体,具有更高的处理效率和实用性。     

Surface potential of ferroelectric domain investigated by kelvin force microscopy

We have investigated the surface potential of poled area by varying the poled size and the sign of applied voltage on 100 nm thick Pb(Zr_0.25Ti_0.75)O₃ films grown by chemical solution deposition using Kelvin force microscopy (KFM). In the negative poled area, as the poled size increases from 300 to 4800 nm, the domain size and the KFM contrast increased in a linear way. However, in the positive poled area, the KFM contrast increased at first and then didn’t increase because of Coulomb repulsion. In two opposite poled areas, the values of the KFM contrast differed because of the internal field near the ferroelectric/electrode interface. These results imply that the surface overcharge of poled area in ferroelectric materials should be increased and the ferroelectric/electrode interface should be improved for the ultra high-density memory device.     

Optical and Electrical Characteristics of ZnO Films Grown on Nitridated Si (1 0 0) Substrate with GaN and ZnO Double Buffer Layers

The optical and electrical characteristics of zinc oxide (ZnO) films grown by molecular-beam epitaxy (MBE) on Si substrates were investigated. ZnO epitaxial layer was successfully grown on nitridated Si(100) substrate initially covered with high-temperature GaN and low-temperature ZnO double buffer layers using MBE. X-ray diffraction and photoluminescence results both indicated that a reasonable quality of ZnO epitaxial layer was obtained. As the CV measurement had indicated, the carrier concentration was reduced virtually in a linear fashion from ZnO surface down to GaN buffer layer. A reduction in electron concentration was caused by the carrier depletion due to the presence of the Schottky barrier of Ni/ZnO. The large density of electron accumulated at the ZnO/GaN interface was due to the large conduction band discontinuity and offset.     

Growth and characterization of device quality ZnO on Si(111) and c-sapphire using a conventional rf magnetron sputtering

In this article, it is shown that high quality ZnO films were grown on Si(111) and Al₂O₃(0001) substrates using a conventional rf magnetron sputtering. High-resolution X-ray diffractometry (HR-XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and photoluminescence (PL) investigations clearly confirmed that the ZnO films grown on Al₂O₃ (0001) at substrate temperatures above 650^∘C are single crystal as well as high optical quality. It is also estimated in both cases grown on Si and Al₂O₃ that an introduction of template pre-grown at 500^∘C can induce a homogeneous interface and improvement of emission characteristic by relaxing the strain caused by large lattice and thermal mismatch between the film and substrate and by reducing defect density in interface region.     

Effects of rapid thermal annealing on surface acoustic wave ultraviolet sensors using ZnO nanorods grown on AlN/Si structures

In this study, we demonstrate a high sensitivity of surface acoustic wave (SAW) ultraviolet (UV) sensor based on ZnO nanorods (NRs) grown on an aluminum nitride (AlN)/silicon (Si) layered structure. The one-dimensional ZnO NRs act as a high-UV sensing material due to their large surface-to-volume ratio. The fabrication of SAW UV sensor is entirely compatible with micro/nano electromechanical (M/NEMS) process with conventional lithography and synthesized ZnO NRs by hydrothermal method at low temperature. The rapid thermal annealing (RTA) process effectively improved the optical properties of ZnO NRs and the sensitivity of the SAW UV sensors. The resulting SAW UV sensors responded to various UV light intensities, and the RTA-processed samples showed high sensitivity. The SAW UV sensor after RTA treatment at 600 °C showed the highest sensitivity with a 130 kHz frequency shift at a UV light intensity of at 0.6 mW/cm², a 5-fold increase in sensitivity compare with as-grown sample.     

Preparation of Ce doped ZnO microspheres and its visible-light photocatalytic activity

Abstract

Using zinc acetate, cerium acetate and glycerol as main raw materials, the Ce doped ZnO (Ce/ZnO) with molar doping ratio of 0.1%, 0.5%, 1.0%, 2.0% and 3.0% were prepared by hydrothermal method at 200?°C. The structure and morphology of prepared Ce/ZnO were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), electron spectroscopy (EDS) and diffuse reflectance spectroscopy (DRS). The visible-light photocatalytic activity of prepared Ce/ZnO was investigated by methyl orange which was used as simulated sewage. The results show that the optimum doping amount of Ce/ZnO is 0.5% Ce, and the band gap width of 0.5% Ce/ZnO is red-shifted from 3.12?eV to 2.79?eV. The morphology of ZnO and Ce/ZnO are all mainly spherical particles. The average particle diameter of ZnO and Ce/ZnO are all from about 3μm to 4μm. The 0.5% Ce/ZnO show highly photocatalytic activity for the degradation of methyl orange under visible light irradiation, and the degradation of methyl orange conforms to the first order power with the apparent rate in paper 0.018?min^?1.     

The annealing effect on properties of ZnO thin film transistors with Ti/Pt source-drain contact

ZnO-based thin film transistors (TFTs) with Ti/Pt contacts were fabricated on SiO₂/Si substrates. The as-deposited ZnO TFT did not work well as a TFT device but the annealed ZnO TFT showed acceptable characteristics with a mobility (μ_sat), threshold voltage (V_th), on/off ratio and subthreshold swing (SS) of 0.8 cm²/V.s, 2.5 V, over 10⁶ and 0.84 V/dec, respectively. Complete oxygen loss was observed in ZnO after annealing at 300°C under a N₂ atmosphere. The annealing process altered the crystallinity, density and composition of the ZnO active layers due to the formation of oxygen vacancies as shallow donors. This process is expected to play an important role in controlling the TFT performance of ZnO. In addition, it is expected to form the basis of the future electronic devices applications, such as transparent displays and active matrix organic lighting emitted displays (AMOLED).     

Tailoring the structural and optical properties of RF magnetron sputtered ZnO/graphene thin films by annealing temperature

Abstract

ZnO and ZnO/Graphene thin films were deposited on Cu substrate using a low pressure chemical vapor deposition (LPCVD) and the magnetron sputtering method. The impacts of graphene layer growth and annealing temperature on the optical properties ZnO and ZnO/Graphene thin films were investigated by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscope (SEM), X-ray photoelectron spectroscopic (XPS), and photoluminescence (PL) measurements respectively. XRD and SEM results reveal that all the thin films preferred the crystalline [001] orientation along the c-axis direction, which were vertical grown on substrate surface. By comparing the results and analysis of their structure, morphology, chemical bonding and optical property, it is proved that using Graphene as a buffer layer can improve the crystal quality of ZnO thin films. For the annealed ZnO/graphene nanostructures, the area ratio of UV and visible emission region of ZnO/graphene thin films increase with increasing the annealing temperature, reaches a maximum at 500?°C and then starts decreasing with further increase in annealing temperature, which indicating that the controllable ZnO/Graphene thin films have the higher crystallization quality at the annealing temperature of 500?°C. Our results demonstrate that for high quality ZnO/graphene thin films deposition, decreasing the defect concentration should be preferable to simply applying the proper annealing temperature, which might have promising applications for various UV photodetectors devices.     

KFM3系列断路器中典型零部件的铆接工艺工装设计

介绍了两种KFM3塑壳断路器中典型零部件的铆接工装;针对KFM3新品中的灭弧室结构特点,设计了上下带自动压料顶杆结构的铆接工装,分析了试模后出现工件翻转等缺陷产生的原因,并给出了解决方案。工装的结构设计,降低了对工人操作技能的要求,且保证了安全,提高了效率,已在生产中得到了检验。     

Characterization of RF sputtered zinc oxide thin films on silicon using scanning acoustic microscopy

Zinc oxide (ZnO) thin films were grown on silicon (100) substrate using radio frequency (RF) sputtering under various processing parameters including deposition time and annealing temperature. A series of characterization techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and scanning acoustic microscopy (SAM) have been used to analyze the crystallinity and crystal orientation, structural morphology, surface roughness, and acoustic properties of these films. In particular, quantitative analysis of elastic wave propagation in ZnO thin films by scanning acoustic microscopy has been performed for the first time in the present work. It has been shown that the propagation properties of acoustic waves on the surface of ZnO thin films strongly depend on film thickness, crystallinity, and surface roughness. The dispersion properties of surface acoustic waves (SAWs) are observed as a function of ZnO film thickness. The velocities of SAWs range from 5328.3 m/s to 4245.7 m/s with increasing film thickness from 32.5 nm to 2.04 μm, while smoother surface contributes to faster propagation of SAWs.