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1.
本文通过基于共沉淀工艺的双粉法制备了Bi1.76Pb0.34Sr1.93Ca2.0Cu3.06O8+d (Bi-2223)前驱体粉末。在这一过程中,首先单独制备了Bi1.76Pb0.34Sr1.93CaCu2.06O8+d (Bi-2212)和CaCuO2(实际相组成为Ca2CuO3和CuO)粉末,并分别进行了烧结。通过调节共沉淀工艺过程中的pH值,获得了颗粒尺寸不同的CaCuO2粉末,然后将Bi-2212与其按照相组成相组成为1:1进行混合,并装入Ag包套中,通过一系列的旋锻、拉拔和轧制工艺,获得设计尺寸的Bi-2223带材。比表面积测试表明随着pH值从3.0增加到5.0和6.5,获得CaCuO2粉末的平均颗粒尺寸从1.1减小到0.75和0.60 mm。通过扫描电镜对不同尺寸CaCuO2颗粒制备的Bi-2223生带、第一次热处理和后处理之后带材的相组成和分布进行了表征。结果表明,适当尺寸的CaCuO2颗粒可以避免团聚现象的出现,因此有利于高载流性能带材的获得。最终通过进一步调节带材的尺寸,1#带材的性能最高,达到了12200 Acm-2。 相似文献
2.
本文采用初始成分为Tl_1.8Ca_2.6Ba_2.0Cu_3.0O_y,研究了一步合成和二步合成的短时间高温烧结及真空封闭较低温长时间热处理的Tl-2223制备工艺。用上述2种工艺均合成出单相性(2223)好的样品,其超导转变的起始温度Tc_(onset)、零电阻温度Tco以及转变宽度△Tc分别为:一步合成样品Tc_(onset)=135K,Tco=127.5K,△Tc=5.0K,二步合成样品Tc_(onset)=140K,Tc。=128.7K,△Tc=7.5K。从制备工艺方面对提高Tl-2223的Tc进行了讨论 相似文献
3.
4.
研究了Sn-20Bi-0.7Cu-xAg焊料凝固和时效过程中的物相生长动力学。通过实验和数值分析相结合分析了Ag含量和时效条件对界面结构和生长的影响,实验中对Sn-20Bi-0.7Cu分别添加了质量分数0.1%、0.4%、0.7%、1.0%、1.5%的Ag。为验证焊接接头的服役可靠性,在85℃和85%的湿度条件下,将接头放置0、10、30、50、100、200和500 h。采用扫描电镜等设备分析时效过程中界面化合物的形貌、厚度和分布,分析了β-Sn的形核界面和取向。结果表明,焊料中Ag含量的增加可以抑制界面Cu6Sn5层的生长,等温时效期间金属间化合物(Cu6Sn5+Cu3Sn)的生长为扩散控制机制。焊接时形成的扇贝状表面在时效时消失,这表明在垂直于界面方向上的生长机制变为稳定性增长,说明Ag3Sn有效降低了Cu6Sn5的生长动力。 相似文献
5.
L.H. Jin G.Q. Liu X.Y. Xu G.F. Jiao H.L. Zheng Q.B. Hao S.N. Zhang C.S. Li P.X. Zhang 《Ceramics International》2021,47(3):3299-3305
Bi2Sr2CaCu2Ox (Bi-2212) precursor powders were synthesized by the oxalate freeze drying (OFD) method. In comparison with the traditional method, the novel method could shorten the processing steps and thus improve the fabrication efficiency of precursor powder. The phase, microstructure and superconducting properties of Bi-2212 precursor powders and wires were characterized by X-ray diffraction, scanning electron microscopy and four-probe method, respectively. The thermal behavior, surface area and particle size of powders were also discussed. The results indicated that large surface area and small particle size might improve the reactivity and uniformity of powders. These properties were beneficial for the rapid and homogeneous formation of Bi-2212. High-purity crystallized Bi-2212 powders without Bi-2201 and alkaline-earth cuprates phases could be achieved. Furthermore, multi-filamentary Bi-2212 wires with OFD powders showed good microstructures without noticeable pores and large secondary particles. Therefore, high engineering critical current densities (Je) of 1619 A/mm2 and critical current densities (Jc) of 7039 A/mm2 were obtained in Bi-2212 wires at 4.2K, self field. It indicated that the oxalate freeze drying method would be a potential candidate for the mass production of high performance Bi-2212 wires. 相似文献
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7.
The Mn-doped compounds Bi1.4La0.6Sr2CaCu2Oy were prepared by sol-gel method. The structural variation was characterized systematically by X-ray diffraction (XRD), infrared (IR) spectra and Raman scattering spectra, respectively. The electrical and magnetic properties of the compounds were investigated by the temperature dependence of resistivity (R-T) and magnetic hysteresis loop (M (H)) measurements. Results indicate that the subtle change of lattice parameters has taken place in the compounds, which is attributed to CuO2 planes canting and Mn valence alternation. In the condition of preserving Bi-2212 structure, Bi1.4La0.6Sr2CaCu2−xMnxOy compound has optimal resistivity and magnetism at x = 2%, which could provide a candidate as new barrier in Josephson junction in future. 相似文献
8.
A.I. Abou-AlyR. Awad S.A. MahmoudM.ME. Barakat 《Journal of Alloys and Compounds》2011,509(27):7381-7388
This work studied X-ray powder diffraction (XRD), electrical resistivity and electron paramagnetic resonance (EPR) measurements for Bi1.8Pb0.4Sr2Ca2.1Cu3−xRuxO10+δ (0.0 ≤ x ≤ 0.4) superconducting samples. XRD analysis and electrical resistivity data showed that the low-content of Ru, x ≤ 0.05, enhanced both the phase formation and the superconducting transition temperature of (Bi, Pb)-2223 phase. A phase change from (Bi, Pb)-2223 phase to (Bi, Pb)-2212 phase was reported for x ≥ 0.15. Two EPR lines were observed for 0.0 ≤ x ≤ 0.075, indicating the presence of both (Bi, Pb)-2223 and (Bi, Pb)-2212 phases. While, one EPR line was observed for x ≥ 0.15, corresponding to the (Bi, Pb)-2212 phase formation. The number of spins (N) participating in the resonance and its spin paramagnetic susceptibility (χ), for the two phases, were calculated as a function of both Ru-content and temperature. In addition, we reported the variation of activation energy (Ea), Curie constant (C), Curie temperature (θ) and effective magnetic moment (μ) with Ru-content. 相似文献
9.
A practical Bi-2223 superconducting magnet, working in liquid nitrogen (L.N2), was designed and fabricated. Bi-2223 tape with a critical current of 147 A was prepared by a controlled overpressure (CT-OP) process at 77.3 K in self-field. Ten double-pancake coils were resistively connected by copper terminals. The bore diameter was 54 mm?, the magnet outer diameter was 122 mm?, the height of the magnet was 124 mm, and the weight of the magnet was about 3 kg. The maximum magnetic field at the center of the bore was 0.48 T with an operating current of 50 A. The experimental results agree well with design predictions calculated by finite element method. AC operation was also performed, and no distortion of the voltage waveform was observed. Therefore, this Bi-2223 superconducting magnet is a suitable replacement for copper magnets designed for applications in science and technology. 相似文献
10.
Bi Yue Wang Sansheng Hao Qingbin Inertial technology Key Laboratory of Fundamental Science for National Defense Beihang University Beijing China Northwest Institute for Nonferrous Metal Research Xi an 《稀有金属材料与工程》2011,(Z3)
This paper have made a systematic study of the superconducting Bi-2212 phase transition temperature, which has a transition temperature (Tc) around 80-93 K, and depends on precise control of synthesis conditions, mainly including heat treatment parameters, oxygen partial pressure, and annealing temperature. Partial melting of the sample during preparation helps to raise its Tc. To elucidate the origin of this strong effect, the samples were heated with different melting process. The rapid changes in Tc valu... 相似文献