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1.
Because of the different ways in which contact materials work, the basic requirements for silver metal oxide contact materials are different. They are anti-welded and anti-erosion when closed, anti-erosion when broken, and arc easily moved and have smaller contact resistance. In this paper, La2O3 is used as a stable oxide in contact material to replace CdO. A new type of Ag/SnO2-La2O3-Bi2O3 contact material is first obtained through using powder metallurgical method. Then electrical contact material parameter tester is used to test the electrical contact performance of the contact material. Through experiments, the arcing voltage and current curves, arcing energy curves, fusion power curves while broken and contact resistance while closed were obtained. Analysis of the results showed that the addition of La2O3 makes the contact material have the following advantages: smaller electrical wear, smaller arc energy, smaller contact resistance and arc is more easily extinguished. 相似文献
2.
WANG Jing-qin WANG Hai-tao WEN Ming ZHU Yan-cai 《浙江大学学报(A卷英文版)》2007,8(3):459-463
Because of the different ways in which contact materials work, the basic requirements for silver metal oxide contact materials are different. They are anti-welded and anti-erosion when closed, anti-erosion when broken, and arc easily moved and have smaller contact resistance. In this paper, La2O3 is used as a stable oxide in contact material to replace CdO. A new type of Ag/SnO2-La2O3-Bi2O3 contact material is first obtained through using powder metallurgical method. Then electrical contact material parameter tester is used to test the electrical contact performance of the contact material. Through experiments, the arcing voltage and current curves, arcing energy curves, fusion power curves while broken and contact resistance while closed were obtained. Analysis of the results showed that the addition of La2O3 makes the contact material have the following advantages： smaller electrical wear, smaller arc energy, smaller contact resistance and arc is more easily extinguished. 相似文献
3.
针对实验研究中物理、化学材料的电性能测试,分析微弱电流测量的方法,提出一种基于OPAⅢ运算放大器的微弱电流信号测量电路的设计,使其能配合数据采集卡对阻抗较大的材料进行电性能的测试. 相似文献
4.
ZHOU Yi-lin ZENG Ning XU Liang-jun JORGENS Stefan 《浙江大学学报(A卷英文版)》2007,8(3):384-392
A kind of low power connector used e.g. in household appliances was partly burned in routine experiment. The heat sources were four paralleled contacts constructed by springs (Sn/CuSn-alloy) in socket and a plug sheet (Ni/Steel) while mating. The contact interfaces were detected by scanning electronic microscope (SEM) and X-ray energy dispersive spectros- copy (XEDS), obvious wear tracks and various contaminants, including element Si, Al, Na, K, S, Cl, O, etc., were found. The contamination degrees on the four paralleled contacts were different, so that the ratio of average contact resistance on the four contacts was about 5:8:3:1. The maximum contact resistance on contacts of the plug sheet reached 28 ?. The main failure rea- sons were fretting and contamination between the contact interfaces. Fretting simulation showed that connection resistance of connectors was raised up, even to ohms level. When the current increased to 5 A, the socket housing was heated and decom- posed. By the thermal analysis, it was estimated that the connector would be burned under the lower current if the current was not evenly distributed on the four paralleled contacts caused by uneven contamination. Improvement methods for connector failure are also discussed. 相似文献
5.
郭晓霞 《深圳职业技术学院学报》2008,7(1):17-21
电火花沉积工艺（ESD）是一种脉冲微弧焊工艺,用高电流的短脉冲把电极材料沉积到基体金属表面,微量的电极材料在脉冲等离子弧的作用下熔化并在基体表面快速固化形成涂层,涂层与基体表面材料呈冶金结合。电火花沉积工艺不仅可以用来填充零件的破损区域,还可以用在表面涂层。对于修复,大部分可以在现场进行,而且只需很短的时间。电火花涂层适合用于高应力、高温、易磨损、易腐蚀等的恶劣的环境下。文中对该工艺的原理、优点、缺点以及研究的热点进行了详细介绍。 相似文献
6.
船用海水阀件是船上海水系统中最容易被腐蚀破坏薄弱环节,船用阀件的腐蚀机理主要有电化学腐蚀、浓度差电池腐蚀,另外流速、温度和微生物对阀件腐蚀也有影响。船用阀件材料的选择的总体原则是根据阀件的阀门类型、介质种类和工作环境（压力、温度和湿度等）选择合适的阀件材料,如铸铁和碳钢、不锈钢、奥氏体铸铁、铜合金等。船用阀件的耐蚀抗腐措施主要从材料选择、表面处理、防腐抑制剂、电防蚀四个方面着手。 相似文献
7.
Selective laser melting (SLM) is one type of additive manufacturing which produces metal parts by powder bed fusion. Since the materials undergo repeated and sharp heating/cooling cycles, the SLMed parts have unique microstructures. The relations among SLM processing parameters, resultant microstructures, and mechanical properties have been investigated by many researchers. However, the wear performance of SLMed materials under various contact conditions has not been carried out until recently. This paper is a presentation of previous and recent research related to wear performance. This is a crucial aspect if SLM is to be expanded to produce friction pairs. Wear rates and mechanisms of the SLMed materials under dry, boundary lubrication, cavitation erosion, and corrosion conditions are discussed and compared with conventionally processed (CP) materials. SLMed materials benefit from fine grains and high hardness, which have higher wear resistance than CP materials. Moreover, a unique tribo-layer on the surface of the SLMed part is found to protect the bulk material under boundary lubrication conditions. An optimized combination of processing parameters increases part density, which further improves the wear resistance. Future work includes studying the influence of pores on the deforming and lubricating behaviors from dry conditions to different lubrication regimes. The final target is to actively control the processing parameters to obtain desirable material properties for improving wear performance. 相似文献
8.
The various stages and progress in the development of interconnect materials for solid oxide fuel cells (SOFCs) over the last two decades are reviewed. The criteria for the application of materials as interconnects are highlighted. Interconnects based on lanthanum chromite ceramics demonstrate many inherent drawbacks and therefore are only useful for SOFCs operating around 1000 ℃. The advance in the research of anode-supported flat SOFCs facilitates the replacement of ceramic interconnects with metallic ones due to their significantly lowered working temperature. Besides, interconnects made of metals or alloys offer many advantages as compared to their ceramic counterpart. The oxidation response and thermal expansion behaviors of various prospective metallic interconnects are examined and evaluated. The minimization of contact resistance to achieve desired and reliable stack performance during their projected lifetime still remains a highly challenging issue with metallic interconnects. Inexpensive coating materials and techniques may play a key role in pro moting the commercialization of SOFC stack whose interconnects are constructed of some current commercially available alloys. Alternatively, development of new metallic materials that are capable of forming stable oxide scales with sluggish growth rate and sufficient electrical conductivity is called for. 相似文献
9.
Ａｔｐｒｅｓｅｎｔ,Ｂｉ(2 2 2 3) /Ａｇｍｕｌｔｉｆｉｌａｍｅｎｔａｒｙｓｕｐｅｒ ｃｏｎｄｕｃｔｉｎｇｔａｐｅｓａｒｅｃｏｎｓｉｄｅｒｅｄｔｈｅｍｏｓｔｓｕｉｔａｂｌｅｈｉｇｈｔｅｍｐｅｒａｔｕｒｅｓｕｐｅｒｃｏｎｄｕｃｔｏｒｓ (ＨＴＳ)ｔｏｂｅａｐｐｌｉｅｄｔｏｓｕ ｐｅｒｃｏｎｄｕｃｔｉｎｇｍａｇｎｅｔｉｃｅｎｅｒｇｙｓｔｏｒａｇｅ(ＳＭＥＳ) ,ｓｕｐｅｒ ｃｏｎｄｕｃｔｉｎｇｍａｇｎｅｔｓ,ｓｕｐｅｒｃｏｎｄｕｃｔｉｎｇｆａｕｌｔｃｕｒｒｅｎｔｌｉｍ ｉｔｅｒｓａｎｄｃｕｒｒｅｎｔｌｅａｄｓ,ｅｔ… 相似文献
10.
ZHANG Ji-gao 《浙江大学学报(A卷英文版)》2007,8(3):361-369
Particle pollution in air, also sometimes known as fine dust contamination, may cause electric contact failure. Recent research further proved that the fine particle is becoming a major disruption of the electronic connectors in signal transmission system. This paper specifies the connector contact in mobile phone application. To study the contact failure of mobile phone, a series of inspections and analytical research methods are introduced. Special features that cause the contact failure are summarized. Particle accumulation is the main problem; organic material such as lactates from sweat of the human body may act as adhesives to stick the separate particles together and make them adhere on the contact surface; chemical properties of dust cause serious local corrosion. The corrosion products may trap the particles and firmly attach on the contact surface; micro motion frequently occurs at the contact interface. Hard particle can be embedded into the surface, and soft particle could be squeezed and inserted into the contact; silicon compounds in dust play the most important role in forming high resistance regions that lead to failure; deposition of particles depends on the amount of materials, static electricity attracting force and gravity force applied on the particles. Current dust test can hardly reflect the serious contact failure. It is difficult to simulate the complexity of contact failure caused by particle contamination. Thus alternative ways of simulation experiment and improvement of contact reliability are proposed. 相似文献
11.
LV Bin ZHOU Sheng-jun ZHAO Lan-yan 《浙江大学学报(A卷英文版)》2007,8(3):506-510
Pin and socket contacts are the key parts of electrical connector as aerospace electronic components. The contacts are also the direct carriers for signal transmitting of electronic equipments, passing the signal from the input end to the output end of electrical connector. The reliability of pin and socket contacts directly influences signal transmission. The goal of this study is to enhance the contact reliability of aerospace electrical connector. Computer simulation analysis was made on contacts performance data by utilizing the simulation system developed by PCL Language of MSC software. Furthermore, the results were experi- mentally validated so as to realize the objective of optimizing contacts design. 相似文献
12.
13.
耐力素质是人体长时间进行肌肉工作的能力,是一切体育运动的基础。然而,当今我国大学生的耐力素质普遍下降。通过对四所大学480名女大学生在实施耐力素质训练前后各项机能指标测试,发现经常进行耐力练习的学生心肺功能都有明显的提高。 相似文献
14.
Electrical Conductivity and Corrosion Resistanceof ZnFe_2O_4Based Materials Used as Inert Anodefor Aluminum Electrolysis 总被引：1，自引：0，他引：1
１ Ｉｎｔｒｏｄｕｃｔｉｏｎ Ｉｎ１８８９,Ｃ．Ｍ．Ｈａｌｌａｐｐｌｉｅｄｔｈｅｆｉｒｓｔｐａｔｅｎｔｏｎｉｎｅｒｔａｎｏｄｅｆｏｒａｌｕｍｉｎｕｍｅｌｅｃｔｒｏｌｙｓｉｓ［１］．Ｆｒｏｍｔｈｅｎｏｎ,ｔｈｅｒｅｈａｖｅｂｅｅｎａｑｕｉｔｅｎｕｍｂｅｒｏｆｐａｔｅｎｔｓａｎｄｉｎｖｅｓｔｉｇａｔｉｏｎｓｏｎｔｈｉｓｓｕｂｊｅｃｔ,ｂｕｔｎｏｎｅｏｆｔｈｅｍｈａｓｂｅｅｎｐｕｔｉｎｔｏｐｒａｃｔｉｃｅ．ＢｉｌｌｅｈａｎｇａｎｄＯｙｅｈａｄｓｕｍｍａｒｉｚｅｄｔｈｅｒｅｓｅａｒｃｈｗｏｒｋｓｂｅｆ… 相似文献
15.
孟继超 《内江师范学院学报》2012,27(5):83-85
自改革开放以来,大量的农村剩余劳动力向城市转移,进城务工的农民工为社会主义现代化建设做出了巨大的贡献。农民工虽然在体力、耐力以及年龄等方面具有一定的优势,但是普遍存在着文化水平不高、劳动技能低下、适用新工艺较慢的弱点。在贯彻和落实科学发展观、构建社会主义和谐社会的大背景下,要将农民工培养成合格的社会主义建设者,就必须优化现有的农民工培训机制,而这一切又离不开法律的规范和保障。 相似文献
16.
HQ-01酸化缓蚀剂的研究 总被引：1，自引：0，他引：1
霍卫青 《新乡师范高等专科学校学报》2003,17(5):19-21
介绍了HQ-01酸化缓蚀剂的合成方法,缓蚀性能及其作用原理。采用工业喹啉、氯化苄、非离子型表面活性剂及甲醇为原料合成HQ-01。通过室内动静态挂片试验,结果表明,它的缓蚀性能较好,腐蚀速率均在2级以下,而且在水中和酸中均匀分散,无液液分层、液固分层现象,和其他酸液配伍性好,不会对地层造成堵塞。它的作用机理主要是由于抑制了腐蚀电化学的阳极、阴极过程,而在金属表面形成了多分子的吸附层保护膜的结果。 相似文献
17.
YAO Fang ZHENG Jian-rong HUANG Zhang-wu 《浙江大学学报(A卷英文版)》2007,8(3):485-489
The dynamic contact resistances of HH52P electromagnetic relays are measured under different ambient air tem- perature. Their diagnostic parameters are extracted and determined. It is found that the ambient air temperature obviously influ- ences some parameters. In order to research its influence on the electrical contact reliability of electromagnetic relay, the statistic analysis is applied to study the static contact resistance, the max of the dynamic contact resistance and the bounce time. It is found that the ambient air temperature regularly influences the three parameters. Thoroughly, the phenomenon is studied and analyzed in the point of material science so as to probe into the essential matter of it. 相似文献
18.
R. GOBIN 《European Journal of Engineering Education》1987,12(3):253-257
Engineering education should be relevant to the needs of our industry as industry absorbs the large majority of our engineering students, either directly or indirectly. The contact between industry and engineering students has therefore to be stimulated. As no legal obligation exists in Belgium, this is left entirely to the initiative of the professors and the engineers in industry. We will explain how at our university those contacts are developed for the mechanical engineering students. We will explain our aims, our working conditions and circumstances, our results and the role of the research. The art however is to stimulate the students, and to convince the industry of the importance of those contacts in the education of our and their future engineers. 相似文献
19.
Amorphous InGaZnO (a-IGZO) films were deposited on the corning eagle XG (EXG) glass substrates using magnetron sputtering
method. The structure, surface morphology, electrical and optical properties of these films were investigated by X-ray diffraction
(XRD), scanning electron microscopy (SEM), semiconductor parameter analyzer and spectrophotometry, respectively. The influence
of oxygen flow on the electrical properties of IGZO thin films was studied, showing that increasing oxygen flow changes the
resistivity with six orders of magnitude. The contact resistance of ITO/IGZO is 7.35×10−2 Ω·cm2, which suggests that a good ohmic contact exists between In2O3: Sn (ITO) and IGZO film. 相似文献
20.
AlSi12 samples were prepared by selective laser melting (SLM) under different processing conditions in order to obtain different top surface morphologies, where single tracks were produced using a fixed processing parameter to reveal the mechanism of the single track on different morphologies. The results show that the morphologies of single tracks changed with roughness of the top surface (Top Ra) of SLM parts, reflected in the variation of wetting angles on the surface processed previously as well as in dimensions of height, width, and depth at the cross-section of each single track. These changes were mainly caused by different wettability and flow behavior of the molten metal under various solidification environments of the single track during SLM. A poor solidification environment in which numerous balls existed limited an effective wetting behavior of molten metal on a previously processed surface of a SLM sample because of an increasing solid-liquid contact area, thus causing dramatical instability of the melt pool and attendant inferior processability of the single track. Meanwhile, under the action of surface tension, the molten metal had a high tendency to transfer into a pore near the single track to form an extending track or flow toward an upper region of melt to form a balling track, hence showing various morphologies of single tracks. This study proposes a theory of the solidification mechanism of single track on the non-ideal surface to provide a better understanding of the SLM processing of Al-Si alloy. 相似文献