用于材料表面改性的空气介质阻挡放电发射光谱研究

设计了一套材料表面改性试验装置，对其放电特性以及由丝状放电向准辉光放电转变的条件进行了试验。利用发射光谱技术和电压电流测试技术，研究了常温常压下空气介质阻挡放电所加电压和输入能量对N2（C^3Πu→B^3g）发射光谱强度的影响。N2（C^3Πu→B^3Πg）的发射光谱强度随放电电压及输入能量的增加而增强，当电压（频率）和输入能量增大某一值后，N2（C^3Πu→B^3g）的发射光谱强度增强速率变大，介质阻挡放电从丝状放电过渡到准辉光放电模式，产生均匀分布的发光现象，这非常有利于对薄膜和金属材料表面的改性。     

化学镀Ni-P对高压输电线表面润湿性的影响

为了增加高压输电线表面的润湿性,降低电晕放电引起的可听噪声,对喷砂处理后的高压输电线表面先进行碱性预镀,再进行酸性化学镀Ni-P处理,得到表面粗糙、厚度为0.1 mm的化学镀Ni-P涂层。结果表明,化学镀层的硬度为1 100 HV,表面润湿角为23.5°。高硬度、高粗糙度的化学镀Ni-P涂层提高了高压输电线表面对液体的表面张力,使高压输电线表面的润湿性增大,不容易产生水珠,降低了电晕放电引起的可听噪音。     

等离子电解渗入工艺和渗层组织

介绍了液相等离子体电解渗入技术,即利用液相中的等离子放电实现渗碳、渗氮、渗硼及多元共渗的基本工作原理、工艺特点和电解液成分等。论述了液相等离子体电解渗入过程中的电流-电压特性和物理化学效应。介绍了经液相等离子体电解渗入处理的20CrMnTi和40Cr钢的表面形貌、渗层显微组织和硬度分布。     

冷却速度对Ml(NiCoMnTi)_5贮氢合金电化学性能的影响

对不同冷却速度下制成的具有同一成分的贮氢合金做了电化学充放电循环实验,比较了它们的容量、电化学循环稳定性及放电电压性能高的冷却速度导致放电容量特别是大电流放电容量较大幅度下降,活化困难,放电电压也有所降低,但改善了合金的循环稳定性及放电电压平台特性．     

冷却速度时Ml（NiCoMoTi）5贮氢合金电化学性能的影响

对不同冷却速度下制成的具有同一成分的贮氢合金做了电化学充放电循环实验,比较了它们的容量、电化学循环稳定性及放电电压性能。高的冷却速度导致放电容量的特别是大电流放电容量较大幅度下降,活化困难,放电电压也有所降低,但改善了合金的循环稳定性及放电电压平台特性。     

电火花堆焊表面残余应力场数值模拟

对电火花堆焊热过程和应力变化过程进行仿真研究,为优化堆焊参数提供快捷可靠的依据。通过研究电容击穿空气的放电特性模型,提出新型电火花堆焊能量来源于电容空气放电的火花产生阶段。建立了三个不同电压参数下的单脉冲温度场模型。利用ANSYS软件对单脉冲放电时电极表面的温度场和应力场进行仿真研究。对多脉冲条件下基体表面应力状态进行仿真研究并与单脉冲条件下的应力场进行对比分析。     

氧化物添加剂对Ni／MH动力电池低温高倍率放电性能的影响

研究了不同氧化物添加剂（CoO,CuO,LazO3,和Y2O3）在高倍率和低温放电条件下对负极性能的影响及机理。实验主要测试的性能有低温放电容量,高倍率（1C,3C,5C和10C）放电容量、充放电电压平台、循环寿命、循环伏安特性和交流阻抗谱,并且分别用SEM、EDS分析了极片的表面形貌和成分。     

输电线表面TiO_2涂层的光催化效率研究

为了降低交直流输电线表面污闪放电和电晕放电,采用等离子喷涂技术在铝输电线表面制备了不同晶型的TiO2涂层,对表面有不同晶型TiO2涂层的输电线施加交直流外电压,研究了TiO2涂层降解甲基橙速度,评价TiO2涂层在外电压条件下的光催化性能。结果表明,无外加电压条件下,二氧化钛涂层自身的光催化性很弱,外加交直流电压能够显著地提高涂层的光催化效率,其中直流电压条件下的光催化效率最为显著,并且随着外加电压的升高,涂层的光催化效率相应提高。90%的金红石相、9%的锐钛矿相TiO2和1%的Y2O3组成的喷涂粉末制备的TiO2涂层在交直流电场中,较短的时间就有较高的光催化效率,外加30 V的交流电压60 min,光催化效率可达到25%,外加30 V的直流电压30 min,光催化效率可达到60%以上。     

网电极沿面介质阻挡放电等离子体润湿性改性及清洗性能研究

目的 针对大气压等离子体装置存在的等离子体面积小、温度高及均匀性差等问题，研发一种网电极沿面介质阻挡放电装置和等离子体清洗平台。方法 通过静电场仿真和实验，优化装置的结构参数，通过分析放电波形探究装置的放电特性。最终确定网孔的对角线尺寸为6 mm，采用厚度为0.3 mm的云母片作为介质材料。通过清洗平台对涂有润滑油的玻璃表面和铝片表面进行清洗实验，并通过AFM、SEM、EDS对清洗前后的表面形貌和元素组分进行分析，探究等离子体清洗机理。结果 放电装置的电场强度和放电功率与网孔尺寸、介质材料的相对介电常数及放电电压呈正相关，与介质厚度呈负相关，放电装置的放电功率随着频率的增加呈先增大后减小的趋势，样品表面接触角随着电压的增大显著降低，随着放电频率的增加呈先减小后增大的趋势，并在5.29 kHz时达到最大放电功率(79 W)。通过试验得到了玻璃的最优清洗参数，电压峰值为11.52 kV，放电频率为5.29 kHz，处理距离为0.3 mm，处理时长为20 min，样品移动速度为2 mm/s。得到了铝片的最优清洗参数，放电电压峰值为11.60 kV，放电频率为5.29 kHz，处理距离为0.3 mm，处理时长为30 min，样品移动速度为2 mm/s。结论 从润湿性改变、光学显微镜照片、扫描电镜、原子力显微镜及表面元素的角度对样本表面的油污进行检验，经检验发现，样品表面的油污被去除，并显著改善了其润湿性。等离子体清洗以化学反应为主，可在不对表面造成损伤的前提下去除表面有机污染物。     

电化学放电线切割电压-电流特性研究

设计并搭建了基于水平走丝方式的电化学放电线切割加工装置,可用于非导电硬脆材料的微细线切割加工,研究了加工过程中的电压电流特性。当电压超过临界值后,电极丝表面会形成不稳定的气层并产生放电现象;随着电压升高,放电状态由火花放电向电弧放电过渡。对石英玻璃的加工实验结果显示,通过增加电压并使放电电压维持在火花区内,能在保证表面质量较好的同时提高加工效率,在电弧区加工可得到更高的材料去除率,但工件表面质量会下降。     

硅橡胶表面老化、改性与修复的研究

主要探讨了硅橡胶表面产生电晕老化的原因和电晕老化的评估方法,并介绍了氢氧化铝(ATH)等无机填料对硅橡胶表面抗电晕老化改性的影响,归纳了硅橡胶表面紫外老化发生的机理以及相应的紫外老化评估手段.另外,讨论了二氧化钛、二氧化铈等光屏蔽剂以及紫外线吸收剂对硅橡胶表面耐紫外辐照老化性能的作用,总结了硅橡胶表面出现热老化的原因、...     

Characteristics of Tantalum Surface Treated by 6-Triethoxysilylpropylamino-1,3,5-Triazine-2,4-Dithiol Using XPS

The characteristic of material surfaces has a vital status in its application,for instance,surface properties of materials play a decisive role in adhesion technology between different materials.A method called molecule adhesion technology which can successfully adhere different materials such as polymers,rubbers,metals and exhibit strong adhesion strength without any adhesive agents.In this work,the rare metal of tantalum surface treated by corona and a molecular adhesive(6-triethoxysilylpropylamino1,3,5-triazine-2,4-dithiols,TES)has been investigated to clarify the reaction mechanism between tantalum and TES.Chemical structures of surfaces treated by corona and TES were also analyzed.TES contains two functional groups:one is alkoxysilyl group which can react with the OH group linked tantalum formed by the corona discharge treatment;the other is dithiol triazinyl group reacted with many other materials.Blank tantalum,corona treated and TES treated surfaces situation were analyzed by X-ray photoelectron spectroscopy(XPS).The result shows that the functional structure of OH groups was formed after corona discharge process and TES can be successfully reacted on the tantalum surface.This research can be as a preparation work to achieve the tantalum and other materials adhesion by using molecule adhesion technology in the MEMS and NEMS electronic device fields.     

Generalization of the Townsend current-voltage characteristics of a corona discharge

The statistical treatment of the current-voltage characteristics of a corona discharge in gases and the generalization of them on the basis of the theory of similarity is considered. The dependence of the corona discharge current on the applied voltage is assumed to be two-parametric of the Townsend type. The parameters of the current-voltage characteristics are found using the least squares method on the basis of experimental data. The calculated current-voltage characteristics are reduced to a dimensionless form and are generalized in the form of the equation of the first quadrant bisector. The criteria and conditions of similarity of corona discharges are found. By the example of a positive corona discharge in helium at different pressures, there is generalized a number of experimental current-voltage characteristics using the proposed method.     

RE-W cathode discharge properties in N2 and CO2 atmosphere at high temperature up to 1000 °C

Rare earth-tungsten (RE-W) cathode discharge properties in N₂ and CO₂ atmosphere at high temperatures were studied experimentally. The effect of temperature, atmosphere, cathode material and diameter on discharge current and corona inception voltage were investigated. The results show that the discharge current is larger and the corona inception voltage is lower in N₂ atmosphere than in CO₂ atmosphere. The range of the corona discharge voltage is narrower in CO₂ atmosphere. When the temperature is above 900 °C, the corona discharge becomes very unstable. As the temperature increases, the discharge current increases obviously and the corona inception voltage decreases significantly. Besides, the discharge current increases and the corona inception voltage decreases with the decrease of cathode diameter. The corona inception voltage also decreases significantly with the decrease of work function of different cathodes.     

低温常压等离子体材料表面改性研究

在低温常压条件下,应用高频高压脉冲电晕放电,在电晕极附近产生高能量(20～50eV)的等离子体。高能等离子体撞击材料表面,使表面性能发生了改变。     

On temperature dependence of the parameters of corona discharge current–voltage characteristics

The dependences of the parameters of corona discharge current–voltage characteristics on the gas temperature are considered in this work. It is shown that the corona discharge ignition voltage U_c(T) of helium and nitrogen decreases with the increase in temperature. The dependence of the parameter A(T) is complicated. It increases at the initial and final sections of the studied temperature range (20–369°C) and decreases at its central portion with two extrema. As the discharge in nitrogen is unstable, we failed to obtain any definite regularity. Generalized dependences that make assertions about the presence of a discharge different from a corona are presented. We made an assumption of an important role of two effects in the observed processes: the absorption of ions by the surface of electrodes and the continuous change in ion mobility due to the ion mass variation in the course of clustering and declustering of ions. It is supposed that there is a dynamic equilibrium between them in a steady state.     

Analysis of the XLPE Insulation of Distribution Covered Conductors in Brazil

Cross-linked polyethylene (XLPE) has been the most common insulation applied to medium voltage covered conductors (MVCCs) in Brazil. The results of accelerated aging tests carried out at high voltage laboratory of UNIFEI (LAT-EFEI), combining the stresses of heat and voltage to ground aiming at enhancing surface corona activity assays, have identified the early failures in XLPE insulations of the Brazilian MVCCs. The observed failures indicate that complementary studies should be performed to better understand the degradation mechanisms of the MVCCs insulations manufactured in Brazil. In this paper, x-ray photoelectron spectroscopy (XPS), contact angle analysis (CA), photoacoustic spectroscopy (PAS), x-ray diffraction (XRD), and atomic force microscopy (AFM) measurements on samples of five Brazilian national/regional MVCCs are reported. XPS, CA, and PAS analysis indicated that a large variety of oxygen-containing groups associated to the oxidation of the XLPE insulations appear to be related to the manufacturing conditions. AFM analysis indicated that the average surface roughness and topography of the XLPE insulation changed significantly and depend on the selected manufacturer. XRD analysis indicates a strong heterogeneity of crystals nucleation that results into different degrees of crystallinity of the Brazilian MVCCs cables. The results of this work indicate strong evidences of manufacturing defects in the XLPE insulation of Brazilian’s MVCCs. The origin of these defects seems to be inherent to the technology used by manufacturers to the production of the MVCCs. The production-related defects are not detectable by the standard tests as partial discharges or even the standard routine—acceptance power frequency assays routinely used in dielectric compatibility tests at high voltage laboratories.     

On the simulation of a corona discharge by the similarity theory methods

A general system of equations for a corona discharge has been derived and reduced to a dimensionless form using the methods of the similarity and dimension theory. Criteria and conditions for the similarity of the processes occurring during a corona discharge have been determined. Formulas for free space-charge density have been derived; the classical structure of the current-voltage characteristic for an arbitrary system of electrodes has been confirmed by different methods: using the theory of similarity, analyzing self-similar solutions, approximating the field distribution, and averaging the equation for the current density with respect to the volume of the interelectrode gap. It has been shown that the quadratic pattern of the current-voltage characteristics of the corona discharge results from the linear dependence of the electric field intensity and the linear threshold dependence of the density of free space carriers on the voltage.     

TiNi形状记忆合金的电火花加工性能

TiNi形状记忆合金由于具有优异的超弹性和形状记忆效应等性能而被大量地应用于工业生产中。然而,形状记忆合金的传统加工相当复杂。因此,研究TiNi形状记忆合金的电火花线切割加工（WEDM）性能。采用L27正交阵列以尽量减少实验。在不同的脉冲持续时间、脉冲关断时间、伺服电压、冲洗压力和线速度条件下进行实验。为同步优化提出一种利用Taguchi设计与实用理念的多响应优化方法。通过对信噪比（S/N）的均值分析和方差分析,确定最佳参数水平。Taguchi分析表明：1μs脉冲持续时间、3.8μs脉冲关断时间、40 V伺服电压、1.8×105Pa冲洗压强和8 m/min线速度,有利于同时使材料去除率最大化和表面粗糙度最小化。TiNi形状记忆合金电火花线切割加工的优化结果表明：脉冲持续时间显著影响材料去除率和表面粗糙度。在较长的脉冲持续时间时,在加工表面可观察到放电坑、微裂纹和重铸层。     

Ti Coating on Magnesium Alloy by Arc-Added Glow Discharge Plasma Penetrating Technique

MAGNESIUM is the8th most abundant element on theearth.Because of that it has some advantageousproperties such as high ratio of strength/weight with adensity that is only2/3that of aluminum and1/4that ofiron,high ratio of rigidity/mass,special characteristicsof electromagnetic shield and shock absorption,excellent cutting and polishing performances,magnesium alloys have been used widely by widely inmany manufacturing industries including aerospace,automobile,electronics and so on.But there i…