高温超导带材接头焊接技术研究

焊接技术是高温超导带材实际应用中的关键技术,焊接温度、焊料、搭接长度等工艺环节对带材接头性能都有一定的影响.本文针对高温超导一代Bi2223/Ag带材和二代YBCO带材的接头焊接工艺进行了系统的实验研究,包括焊接温度对带材性能的影响、不同焊料及搭接长度对接头性能的影响等.实验结果表明:一代Bi2223/Ag高温超导带材在400℃焊接温度以内载流能力不会发生明显退化,而二代YBCO带材对温度较敏感,在200℃以上带材性能会出现明显退化;在Bi2223/Ag及YBCO带材各自的焊接温区内,不同焊料对带材接头性能有一定的影响,但液氮温度下接头电阻均能达到10-8Ω量级,其临界电流与带材短样相比无太大变化;两种超导带材的接头电阻均与焊接搭接长度成反比,适当增加焊接搭接长度可以减小接头电阻,提高带材接头性能.     

二代YBCO带材接头电学性能低温实验研究

针对第二代YBCO高温超导带材接头进行相关电学性能测试,根据对YBCO带材与其他材料焊接接头模型进行电流转移分析,得出接头电阻与YBCO焊接面的电阻率、焊料种类有关。再进行YBCO带材临界电流测试,YBCO二层叠临界电流测试,YBCO带材不同搭接方式的临界电流以及接触电阻测试和不同焊料对YBCO带材接触电阻影响的实验,实验得出YBCO带材的接触电阻与焊料的选择无关,与焊接面有关。     

高温超导带材焊接接头电阻研究

针对高温超导一代Bi2223/Ag带材、二代YBCO带材的焊接问题,理论计算分析了搭接长度、焊锡层厚度对带材接头电阻的影响,并对焊接长度对接头电阻的影响进行了实验验证。实验结果表明:增加焊接搭接长度可以减小接头电阻,两种超导带材的接头电阻皆同焊接搭接长度成反比。当焊接长度在3—5cm,焊料厚度在微米量级时,Bi2223/Ag带材、YBCO带材各自之间的接头电阻在液氮温度下均可控制在10-8Ω左右,能够满足超导装置稳定运行的要求。     

高温超导带材的焊接直角接头电阻研究

为了研究高温超导材料在储能装置中的应用,开展了高温超导D型磁铁的研究。针对高温超导一代Bi2223/Ag带材和二代YBCO带材的直角接头焊接问题,理论分析焊锡层厚度和带材焊接根数对直角接头电阻值的影响。当焊接参数保持稳定时,直角接头的电阻值和焊接根数大致成反比,对带材焊接根数对直角接头电阻的影响进行了实验验证。实验结果表明,可以通过增加带材的焊接根数来有效减小接头电阻,当焊接根数为5,且焊料厚度在微米量级时,两种带材各自之间的直角接头电阻值在液氮温度下均可控制在10-8Ω左右,能够满足装置稳定运行的要求。     

Bi2223/Ag高温超导带材连接技术的研究

钎焊连接是Bi2223/Ag高温超导带材实际应用最多的连接工艺,包括焊接温度、焊料和中间层设计等工艺环节.本文首先对PIT工艺制备的Bi2223/Ag高温超导带材开展了热处理温度-Ic影响试验,通过实验筛选出适合Bi系带材的焊接加热温度.用Sn96CuAg 、Sn60PbAg、Sn60PbSb等三种焊料进行了Bi2223/Ag高温超导带材钎焊实验,研究了钎焊工艺对焊接接头低温电阻影响,建立焊接接头电阻数学表达公式,并利用数学模型讨论了焊接中间层设计优化问题.     

低阻YBCO超导接头的设计和工艺优化

商用YBCO超导带材的长度最多可达千米量级。在实际应用中通常借助接头来连接多根带材。为了降低接头的产热,必须使得接头电阻要尽可能地小。选用两种焊料,以不同工艺制备了若干YBCO超导接头。测试其电性能,并研究了表面预处理方式、焊接长度、加热温度、施加压力等不同工艺参数对其性能的影响。最后指出优化YBCO超导接头的工艺参数。     

高温超导涂层带材接头工艺研究进展

二代高温超导涂层带材因其具有较高的临界温度、临界电流密度和工程临界磁场,被认为是绕制下一代高场强超导磁体最具潜力的材料之一。带材接头对于磁体研制必不可少,其制作工艺和性能测试方法成为国内外许多研究机构的关注重点。文中综合目前高温超导涂层带材接头相关的研究进展和成果,对包括涂层带材的工业制备现状、带材接头焊接工艺、性能测试方法、仿真建模研究等几个方面进行了概述。     

高温超导带材最优焊接长度设计北大核心CSCD

高温超导体在需要高磁场的环境中变得越来越有吸引力,其相较于低温超导体有更高的临界磁场上限.在现今高温超导研究领域,高温超导带材以及线圈之间大多都需要焊接,而焊接电阻的存在严重影响了高温超导体工作时的稳定性与持续性.本文针对两种不同规格的第二代高温超导带材YBCO,在同种焊锡下设计不同的焊接长度进行实验,对实验的结果进行分段分析,根据实验结果,得到不同焊接长度下第二代高温超导带材YBCO的焊接电阻分布,利用最小二乘法拟合出焊接电阻-焊接长度的分布函数.提出了一个新的指标Rd用以表征焊接电阻随焊接长度的变化趋势,并且用黄金分割法求出随着焊接长度的增加,焊接电阻变化率的分布情况.进一步得出了各种焊接电阻变化率条件下的最优焊接长度.着重分析了两种规格的高温超导带材YBCO分别在不同的焊接长度条件下的焊接电阻变化情况,最终得到不同规格高温超导带材YBCO分别的最优焊接长度选择方案.     

HTS电流引线中接头电阻的研究和焊接工艺

针对Bi-2223/Ag-Au高温超导带材制造的二元HTS电流引线设计中不同材料之间连接的技术要求,设计了减小接头电阻的焊接工艺实验,包括焊接温度、焊料、搭接长度和焊锡层厚度对接头电阻的影响。着重分析了HTS电流引线中应用的三种接头的焊接工艺对焊接电阻的影响,并总结出在HTS电流引线中接头电阻的焊接工艺参数。     

高温超导带材最优焊接长度设计

高温超导体在需要高磁场的环境中变得越来越有吸引力,其相较于低温超导体有更高的临界磁场上限.在现今高温超导研究领域,高温超导带材以及线圈之间大多都需要焊接,而焊接电阻的存在严重影响了高温超导体工作时的稳定性与持续性.本文针对两种不同规格的第二代高温超导带材YBCO,在同种焊锡下设计不同的焊接长度进行实验,对实验的结果进行分段分析,根据实验结果,得到不同焊接长度下第二代高温超导带材YBCO的焊接电阻分布,利用最小二乘法拟合出焊接电阻-焊接长度的分布函数.提出了一个新的指标Rd用以表征焊接电阻随焊接长度的变化趋势,并且用黄金分割法求出随着焊接长度的增加,焊接电阻变化率的分布情况.进一步得出了各种焊接电阻变化率条件下的最优焊接长度.着重分析了两种规格的高温超导带材YBCO分别在不同的焊接长度条件下的焊接电阻变化情况,最终得到不同规格高温超导带材YBCO分别的最优焊接长度选择方案.     

Joining of textured YBCO with YBCO added Ag2O additive

The engineering applications of high temperature superconducting (HTS) single domain YBCO block require the material with larger size and more complex shape. However, traditional top-seeded melt growth (TSMG) method cannot meet this requirement. In this paper, solder technology of YBCO blocks using Ag₂O-doped YBCO slice has been performed in air with a rapid cooling rate, and the oxygen treatment techniques with a shorter time were used in the process. Microstructure analysis and superconducting characterization of the joint were investigated. The results show that a high quality joint is obtained without any macro cracks. Furthermore, the grains in the joint are well oriented as same as that of the base YBCO block. However, some defects such as voids and Cu–Ba–O phase segregations are discovered in the middle of the joint. Much finer Y211 (Y₂BaCuO₅) grains are attained in the soldering zone compared with that in the base YBCO. The trapped field measurement on bonded YBCO blocks shows a single maximum, indicating good superconducting properties in the joint.     

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In ITER Feeder system, the superconducting joints and the current leads should use solder to weld. In this paper, Bi-2223/Ag iswelded with different kinds of solders, and the weld procedure and the measuring device are introduced in this paper. The electrical property of the superconducting joint under liquid nitrogen was also measured and the result showed that Bi50Sn9Pb31, In99.99 and high melting point solder Sn96.5Ag3Cu0.5 have a lower resistance under liquid nitrogen, and satisfy the requirement for temperature gradient. This can make a reference for the solder measurement and choice of ITER Feeder system.     

Bi-2223高温超导带材焊接接头电阻和过电流冲击性能实验研究

特变电工股份有限公司,昌吉831100采用自行研制的装置,对不锈钢加强Bi2223/Ag高温超导带材的焊接工艺进行了系统研究,得出最佳的焊接方案.实验测量高温超导带材焊接头的直流电阻,并对带材进行了交流过电流冲击实验,冲击时间为0.5秒,每次冲击的电流依次递增,并在每次冲击后测量焊接头的电阻,直到被测带材烧毁.根据实验数据对样品在过流冲击下的动态电阻进行实验研究,得到了具有实际意义的结果.     

Solderability study of RABiTS-based YBCO coated conductors

The solderability of commercially available YBa₂Cu₃O_7?x (YBCO) coated conductors that were made from Rolling Assisted Biaxially Textured Substrates (RABiTS)-based templates was studied. The coated conductors, also known as second-generation (2G) high temperature superconductor (HTS) wires (in the geometry of flat tapes about 4 mm wide), were laminated with copper, brass, or stainless steel strips as stabilizers. To understand the factors that influence their solderability, surface profilometry and scanning electron microscopy were used to characterize the wire surfaces. The solderability of three solders, 52In48Sn, 67Bi33In, and 100In (wt.%), was evaluated using a standard test (IPC/ECA J-STD-002) and with two different commercial fluxes. It was found that the solderability varied with the solder and flux but the three different wires showed similar solderability for a fixed combination of solder and flux. Solder joints of the 2G wires were fabricated using the tools and the procedures recommended by the HTS wire manufacturer. The solder joints were made in a lap-joint geometry and with the superconducting sides of the two wires face-to-face. The electrical resistances of the solder joints were measured at 77 K, and the results were analyzed to qualify the soldering materials and evaluate the soldering process. It was concluded that although the selection of soldering materials affected the resistance of a solder joint, the resistivity of the stabilizer was the dominant factor.     

核磁共振磁体超导接头工艺研究进展

高度稳定的磁场对于核磁共振（NMR）波谱仪至关重要.为了保持磁场的稳定性,高质量的超导接头必不可少.它在过去几十年中,受到NMR超导磁体研究人员的广泛关注.本文从五个部分介绍了超导接头技术的研究进展：第一部分简要介绍了NMR超导磁体和超导接头的发展;第二部分概述了低温超导体材料之间超导接头的研究进展;第三部分介绍了高温超导体材料之间的接头;第四部分讨论了有关超导接头电阻的测量技术;最后,提出了对超导接头技术研究的展望.     

单畴钇钡铜氧块材高Q值谐振腔研究

 在对高Q值的微波谐振腔的研究中, 尤其是对低温超导谐振腔（超导铌腔）的研究取得了很大的进展，生产加工技术也日趋成熟,而用高温超导材料来制备高Q值的谐振腔还不成熟。从高温超导体的表面电阻，生成方法，物质的微观结构等方面进行分析，实验中，通过一个端面用单畴YBCO块材代替无氧铜，在50K时谐振腔Q值就增加到原来的5倍，在20K时全部用单畴YBCO谐振腔，Q值有望达到铜腔的70倍，谐振腔的性能有明显的提高。     

批量化制备高性能单畴YBCO超导块

用顶部籽晶熔融织构生长法（TSMTG）批量制备了30mm直径的YBCO单畴超导块材，使用一种六面控温的箱式炉和一台改进的坩埚炉进行晶体生长，采用了高压氧化退火工艺对生长出的YBCO晶体进行后处理，与流动氧化工艺相比，在保持样品超导性能不变的情况下高压氧化大大节约了用氧量，缩短了氧化退火时间，提高了生产效率，大多数单畴超导块在77k和0.5T的磁场下的磁悬浮力超过10N/cm^2，其中最高值达到了15N/cm^2，目前我们巳具备了年生产1000块30mm直径优质单畴导块的能力。     

Bi-2223带材有阻焊接接头电阻特性的研究

本文针对Bi-2223/Ag带材接头有阻焊接展开研究,考虑大电流时超导I~V特性非线性影响,建立焊接接头电阻特性的有限元计算模型,总结出不同搭接距离和焊锡层厚度对接头电阻的影响规律,并着重分析了接头电阻对临界电流的影响,最终通过实验验证了理论分析得到的一些基本规律.为降低Bi-2223/Ag带材接头电阻对高温超导磁体运行时的不利影响,实际焊接时搭接距离应保证在7~10cm以上.     

Effects of soft beam energy on the microstructure of Pb37Sn, Au20Sn, and Sn3.5Ag0.5Cu solder joints in lensed-SM-fiber to laser-diode-affixing application

This paper reports on the effectiveness of soft beam energy as a heat source to form an optimum solder joint to fix a lensed fiber permanently on a Ni/Au-plated substrate. Solders, i.e., Pb37Sn, Au20Sn, and Sn3.5Ag0.5Cu (SAC) [wt%] were evaluated for this fluxless application. The microstructures of the solder joints have been examined using scanning electron microscopy (SEM), in order to understand the response of these solder materials to the focussed white light. Obviously, the exposure time has a greater effect on the soldering temperature before reaching the peak temperature, which is determined by the power. A power setting of 40 W can reach approximately 340 °C, 30 W can reach about 310 °C while 25 W can easily reach 260 °C. In general, a higher soldering temperature than the melting temperature is required to form good wetting solder joints for fluxless applications. However, too high an input thermal energy may result in premature aging for the cases of Pb37Sn and SAC, and lateral cracks for the case of Au20Sn. The thermal cracks and voids observed in Au20Sn solder joint were attributed to the fact that the soft beam heating profile does not suit the AuSn preform. Out of these three solder types, SAC demonstrated just the right response to the soft beam, i.e., good wetting, fine and homogeneous structure, and no cracks or other visible failures.