Arc erosion of AgSnO_2 electrical contacts at different stages of a break operation

Arc erosion studies are conducted on AgSnO2 contact materials at different stages in the break operation.A resistive load arrangement is used with up to 42 V DC at 24 A and a constant contact opening velocity.The arc current is terminated at different stages as the arc is drawn between the contacts enabling a study of the arcing phenomena up to that point.Surface profiling of the contacts is conducted to determine the extent of erosion at the different stages as the arc is drawn.Spectral analysis is also conducted on the arc and then related to the extent of erosion.The results show that particular features occur at different stages as the arc is drawn.As the arc is initially established,it goes through an "Arc Generation" regime where the arc roots are small and immobile on both the anode and the cathode.Material transfer occurs mainly from anode to cathode.The spectral analysis indicates that Sn and O species dominate the arc followed by the Ag species.As the arc is drawn further and enters the "Arc Degeneration" regime,the anode undergoes significantly larger erosion than the cathode.Also,both contacts indicate that multiple arc roots have formed,which are highly mobile in the later stages of the discharge.The spectral analysis indicates that Ag and N species are in high concentrations compared to other species.The mechanisms of erosion and deposition are discussed in relation to the species within the arc discharge.For the complete break operation,it is found that the anode undergoes major erosion,and it is thought that the gaseous ions species do not dominate the arc under these conditions of short arcs and voltage 42 V to cause cathode erosion.     

Influence of operation number on arc erosion behavior of Ag/Ni electrical contact materials

Arc erosion behavior of Ag/Ni materials with different operation numbers was investigated by OM, 3DOP and SEM. The results indicated that the arc erosion of Ag/10Ni electrical contact material fabricated by sintering? extrusion technology was more and more serious with the operation numbers increasing from 1000 to 40000. With the same operation numbers, the arc erosion on anode was more serious than that on cathode. Besides, the pores preferred to emerge around the arc effect spot during the first 10000 operations. And the morphology of the molten silver on cathode and anode was different due to the action of gravity and arc erosion. Furthermore, the relationships among arc energy, arc time, welding force, electric resistivity, temperature and mass change on contacts were discussed, which indicated that the mass loss on cathode was mainly caused by the fracture of molten bridge.     

Ag-30W的电弧行为高速摄像及表面侵蚀研究

采用高速摄像的方法,研究了直流条件下Ag-30W电接触材料电弧行为的基本特征和规律。通过扫描电镜技术,探讨了在电弧烧蚀触头表面的微观组织形貌、元素分布等特征。结果表明,电弧演化经历快速起弧、稳定燃烧和迅速熄灭3个过程。电弧烧蚀触头表面形貌由以钨为骨架、银为包裹层的大量凸丘组成。在电弧作用下,银包裹层可以有效保护钨骨架不被烧损,同时减少钨与空气的接触,减轻凸丘处电弧燃烧造成的侵蚀。     

AgWC30电接触材料的电弧行为研究

对电弧基本行为的研究一直是电接触材料领域的研究重点,本研究以AgWC30触头为研究对象,借助高速摄像的手段,观测电触头对在不同工作条件下,电弧行为的基本特征和规律,并进行了定量测量研究。结果表明,电弧演化阶段经历起弧、稳定燃烧、迅速熄灭3个过程。起弧阶段存在多点起弧特征,并伴有明显的金属熔滴的喷溅行为,稳定燃烧阶段出现电弧的产生、长大和合并行为,最后电弧迅速熄灭。通过扫描电镜对燃弧后触头表面的形貌分析,判断触头表面存在以WC为骨架覆Ag的大量凸丘,凸丘与熔桥的产生和断裂行为有密切关系,触头分断过程中熔桥和电弧可同时存在,并存在一定的协助作用。     

气体流量和耦合度对GPCA-TIG焊电弧特性影响的数值模拟

根据磁流体动力学理论和组分守恒建立气体熔池耦合活性TIG焊电弧二维数学模型,采用简化阴极边界层模型将阴极与电弧耦合求解,计算得到了不同外层氧气流量与耦合度下电弧等离子的温度、氧气分布、阳极表面电流密度和热流密度等特征参数。结果表明,与TIG电弧相比,气体熔池耦合活性TIG电弧收缩,流速增大,阳极表面电弧压力升高;增大外层氧气流量或增大耦合度,电弧最高温度均上升,氧气向电弧区域扩散趋势更明显,电弧形貌略有收缩,阳极表面电流密度与热流峰值均略有增大。     

热等静压制备AgZnO电触头材料的组织和性能研究

利用热等静压技术,采用混粉法制备高含量ZnO的AgZnO(12)电接触材料,研究了材料的显微组织,测试了电接触性能。利用扫面电镜(SEM)、金相显微镜(OA)表征了材料的微观形貌和电弧作用后的触点表面形貌。结果表明,热等静压技术能够有效的提高AgZnO(12)的烧结坯致密度;热等静压制备的AgZnO(12)丝材软态抗拉强度达到292 MPa,延伸率达到16%,比同状态下常规烧结的丝材分别提升了5.4%和28%,显微硬度值为80.3,没有明显的变化;AgZnO(12)加工硬化率高,随加工变形延伸率急剧下降;在直流阻性负载下的电弧作用后阳极形貌平整,材料侵蚀以喷溅为主,阴极形貌有富银的凝固凸点,周边形成金属凝固铺层;材料转移为阳极往阴极转移,接触电阻低而稳定,有很好的应用前景。     

新型AgZrB2 触头材料的制备及电气性能

采用超声、球磨和放电等离子烧结相结合的方法制备了不同ZrB₂含量（3%,5%,7%,质量分数）的新型AgZrB₂触头材料,并通过电接触试验研究了触头材料的电弧侵蚀和材料转移行为。结果表明,ZrB₂含量显著影响AgZrB₂触头材料的耐电弧侵蚀性能。Ag-3% ZrB₂触头材料具有稳定的闭合/分断燃弧能量和持续时间,表现出较好的耐电弧侵蚀性能。但是,过多的ZrB₂会导致更高的闭合燃弧能量和更长的闭合燃弧时间,并且分断燃弧能量和时间会产生较大的波动,电弧侵蚀较为严重,这说明过量的ZrB₂不利于提高触头材料的耐电弧侵蚀性能。此外,Ag-3% ZrB₂和Ag-5% ZrB₂触头材料具有相同的材料转移模式——从阳极向阴极转移,而Ag-7% ZrB₂触头材料则呈现出相反的转移模式——从阴极向阳极转移。     

Fe掺杂对纳米复合Ag-SnO2电接触合金电弧演化行为的影响

应用高速数字摄像机和扫描电镜对纳米复合Ag-SnO2，Fe掺杂的纳米复合Ag-SnO2及商用Ag—SnO2-In2O3电接触合金的电弧演化过程和阴极斑点进行了比较研究。结果显示：空气中电弧的演化过程可以分为起弧、稳定燃烧和衰减3个阶段。Fe掺杂后，纳米复合电接触合金电弧演化过程的形弧时间是商用合金的2倍；对触点表面烧蚀起主要作用的稳定燃烧时间短；电弧弧根对应的阴极斑点数量多、跳动迅速、运动区域大；电弧弧根在阴极表面停留的时间短，热流输入少，使其燃弧后阴极斑点分散，烧蚀轻微，具有较好的耐电弧侵蚀性能。     

电极材料组织对真空电弧阴极斑点运动行为的影响

真空电弧在非晶、纳米晶及常规粗品电极合金表面微观分布的观测表明，电极材料显微组织对电弧阴极斑点几何性质和运动行为有明显影响．阴极斑点优先在材料承载电压能力低的弱相表面形成，弱相尺寸、形貌和分布决定了阴极斑点的几何特征．显微组织大幅度细化时，电弧在电极表面分散和快速运动，非晶合金表面仍保持完全非晶结构．分析表明，当材料特征显微组织尺寸小于阴极斑点尺寸时，阴极斑点运动模式从跳跃式运动转变为连续式运动．电极材料组成相的浓度及其尺寸是决定阴极斑点微观迁移方式的重要因素．     

直流条件下W-15wt%Cu电接触材料燃弧特性研究

研究了W-15wt%Cu电接触材料在直流条件电弧作用下电极表面元素分布、材料微观组织形貌;探讨了电接触材料在直流电弧作用下的转移和腐蚀机理。结果表明:直流电弧引起阳极表面熔化、Cu离子向阴极转移并在阴极表面沉积;金属氧化物在电弧高温作用下分解成单元素,吸收了电弧能,有利于灭弧;同时W颗粒悬浮在阳极Cu微小熔池中,增加了熔融Cu的粘度,有利于降低Cu熔滴的飞溅,减少了电弧烧损。W-15wt%Cu复合电接触材料显示出良好的综合电性能。     

双丝夹角对双丝间接电弧特性的影响

建立了双丝间接电弧的三维有限元数学模型,分析了不同双丝夹角对双丝间接电弧特性的影响.利用高速摄像机拍摄电弧图片与计算结果对比,以验证计算结果的准确性.结果表明,双丝间接电弧的温度、速度和电流密度等电弧参数在阴极区和阳极区较高,在弧柱区较低,弧柱区下端最低;随着双丝夹角的增加,双丝间接电弧的温度、速度、电流密度在阴极区、阳极区以及弧柱区上端增加,在弧柱区下端下降;上述电弧参数的变化率在阴极区和阳极区大于弧柱区,阳极区大于阴极区,弧柱区上端大于弧柱区下端;双丝间接电弧的偏转程度随着双丝夹角的增加而增加.     

AgCuO电触头材料的接触电阻及电弧侵蚀形貌分析

采用原位反应合成法制备CuO含量为10%的AgCuO电触头材料,使用接触电阻参数测试仪对试样在不同电流条件下开闭次数与接触电阻的关系进行研究,并通过扫描电镜对试样的阴/阳极表面微观形貌进行电侵蚀特性分析。结果表明,低电流条件下AgCuO电触头材料的接触电阻基本都是先升高,然后在某一开闭次数时急剧下降,最后基本趋于一定值,且AgCuO电触头材料接触电阻会随着试验电流的增加而逐渐降低;当电流达到25A时,AgCuO电触头材料的接触电阻最低,且随开闭次数的增加其接触电阻变化不大,材料的接触电阻表现出极佳的稳定性。电弧侵蚀后的形貌分析发现,阳极表面呈凹凸状,并有气孔和裂纹,而阴极表面呈现浆糊状尖峰结构。     

Duhocamis放电特性之空心阴极与热阴极的协同效应

Duhocamis(双空心阴极金属离子源)是在GSI间热阴极PIG离子源基础上,利用空心阴极圆筒取代空心阳极圆筒,磁镜场取代均匀磁场的强流金属离子源。通过系列变化空心阴极与间热阴极电源电压的弧放电试验,了解其对离子源工作及金属等离子体形成的贡献和影响。试验结果分别给出了空心阴极与间热阴极弧放电特性曲线,它们的弧压对弧流关系具有不同的弧阻抗特性;通过磁分析器对等离子体中各种离子成分比例的分析,进一步显示出空心阴极与间热阴极弧放电两者相互强化和联动的协同效应;尤其空心阴极电位从零开始变化的弧放电试验,揭示了离子源从PIG空心阳极放电向双空心阴极放电转换的过程;协同效应不仅证实空心阴极作为赖以产生金属离子的溅射电极,而且对于确立离子源工作模式与优化产生所需金属离子的放电条件至关重要。     

反应合成AgSnO2电接触材料的电弧侵蚀特性研究

抗电弧侵蚀性能是衡量电接触材料好坏的一个重要指标.本文对采用反应合成技术制备的AgSnO2电接触材料进行电接触试验,并通过扫描电镜观察材料在电弧侵蚀后的形貌,对AgSnO2(10)材料在直流、阻性负载条件下的电弧侵蚀特征进行研究.结果表明,反应合成法制备的AgSnO2(10)电接触材料在电流≤20A条件下,材料由阴极向阳极转移;电流＞20A条件下,材料的转移方向反转.归纳出电弧侵蚀后的AgSnO2(10)的表面形貌特征.     

等离子喷涂Ag-SnO2涂层的微观结构和性能

采用等离子喷涂技术在铜基体表面制备了Ag-SnO2涂层,应用XRD和SEM对涂层的相结构和微观组织进行了表征,通过拉伸和硬度实验测定了涂层的力学性能,并采用电弧侵蚀实验测试了涂层的耐电弧侵蚀性能。结果表明,所得涂层结构均匀致密,涂层内纳米级SnO2颗粒均匀分布在银基体中;涂层的力学性能和电弧侵蚀性能与块体合金接近;电弧侵蚀试验后,涂层表面阴极斑点分散,烧蚀轻微,表明所制备的Ag-SnO2涂层具有良好的耐电弧侵蚀特性。     

Effect of Milling Time on Electrical Breakdown Behavior of Al<Subscript>2</Subscript>O<Subscript>3</Subscript>/Cu Composite

In order to clarify the relationship between the microstructure and the arc erosion behavior of metal-matrix composite, Al₂O₃/Cu composites with different distributions of Al₂O₃ particles were prepared by high energy ball milling and powder metallurgy. The effect of milling time on microstructure, properties, and arc erosion behavior of Al₂O₃/Cu composite was investigated. The results show that the distribution of Al₂O₃ particles improves significantly with increase of milling time, but Al₂O₃ particles will be aggregated if milling time is too long. The optimal milling time is 24 h in the range of experiments. A uniform distribution of Al₂O₃ particles in copper matrix can improve the hardness, electrical conductivity, average breakdown strength, chopping level, and arc life. With improvement in the distribution of Al₂O₃ particles, the erosion area becomes larger, and the erosion pits become shallower and are dispersed more uniformly.     

Electric Characteristics of Plasma Arc Produced by Bi-Anode Torch

In order to improve the voltage control and stability of a plasma arc, a new-type plasma torch was designed and constructed. The torch, called bi-anode torch, has two anodes that were inter-insulated and have different distances from the cathode tip. The position of the arc root can be controlled to attach to either anode surface during operation to obtain a low-voltage and high-fluctuation arc or a high-voltage and low-fluctuation arc. The paper discussed the occurrence of the double-arc phenomenon and its prevention. Experimental work has been carried out to compare voltage-current (U-I) characteristic of the arc when using different plasma gases and anode arc root attaching to different anode surfaces. The results show that the U-I characteristic of the plasma arc is affected by the position of the anode arc root attachment and the composition of the plasma gas, which was explained by a simplified arc model.     

Ag/La2NiO4复合触点材料的制备与性能

利用传统的陶瓷制备工艺制成La2NiO4类金属导电陶瓷,将其与银粉混合制成Ag/La2NiO4复合触点材料,该材料具有电阻率较小,加工性好等特点.X射线衍射分析发现La2NiO4陶瓷在电弧烧蚀作用下相结构不发生变化,具有高的化学稳定性.模拟电寿命实验测得触点材料转移和烧蚀量小,表面抗烧蚀性好.与通用的Ag/CdO和Ag/SnO2触点材料比较,Ag/La2NiO4性能较佳,是一种可以取代Ag/CdO的新型触点材料.     

电弧焊极性选择与电弧阴阳极产热关系

极性选择是焊接工艺中最为基础的参数之一,对焊接质量有着重要的影响.通过分析电弧阳极区中性粒子的电离及阴极(或阴极区)的电子发射过程,研究了各种焊接方法下,阴阳极区压降的变化情况和阴阳极的产热.结果表明,时于不同的焊接方法、不同的极性接法(直流正接或直流反接),阴阳极区的电子发射和电离方式并不相同,在特殊情况下会在阴极区...     

纯银触头熔桥行为高速摄像研究

采用自主设计的电接触-高速摄像试验系统,在直流单分断模式下对纯银触头在电接触过程中所发生的熔桥行为进行观测,从而在不同的电流条件下对电接触过程中熔桥的形貌尺寸进行研究,同时通过SEM对电接触熔桥行为作用后纯银触头的表面进行形貌分析。结果表明,在DC 10 V(8~20 A)条件下,纯银触头在电接触过程中形成的熔桥有圆柱型和哑铃型2种形貌,并且其尺寸为微米级;熔桥的直径和长度都随电流的增大而呈现出先减小后增大的趋势,10~15 A范围内纯银触头在电接触过程中不易形成熔桥,电接触过程中电弧可能先于熔桥而产生,并且熔桥和电弧现象可以同时存在。