高性能YBCO单畴块材的制备及其超导性能的研究

发布时间：2018-01-11 22:15

本文关键词：高性能YBCO单畴块材的制备及其超导性能的研究　出处：《上海大学》2016年博士论文　论文类型：学位论文

【摘要】：RE-Ba-Cu-O(REBCO,RE=Y,Gd,Sm,Nd等)单畴超导块材由于其具有高临界温度(T_c)、自稳定的磁悬浮特性以及比铁磁永磁体更强的磁通俘获能力,因而在超导磁体、超导飞轮储能以及超导无接触传输等强电领域展示出巨大的应用潜力。特别是由于YBCO单畴块材制备工艺简单可靠,制备成本相对低廉,使其成为工业应用领域最有吸引力的材料。为了进一步提高YBCO单畴块材的磁通俘获性能,如何提高块材的临界电流(J_c)和尺寸显得尤为重要。然而目前用于制备YBCO单畴块材的顶部籽晶熔融织构生长技术中还存在着一些问题,如:第二相粒子Y_2BaCuO_5(Y211)的分布不均匀以及多籽晶YBCO单畴块材畴区晶界处由于杂质相的残留导致的弱连接等。因此研究探索如何较好地解决这些问题是进一步提高YBCO单畴块材磁通俘获性能的关键。本论文的主要研究目标是通过解决上述目前存在于顶部籽晶熔融织构生长技术中的问题进一步提高单籽晶和多籽晶YBCO块材的磁通俘获性能。主要的研究内容和结果如下:1.研究了Y211相含量对YBCO单畴块材生长的影响。通过对不同Y211相含量的前驱粉体进行热分析测量和淬火生长实验,结果发现随着前期粉体中Y211相含量的增加,YBCO熔体的结晶温度降低;随着前驱粉体中Y211相含量的增加,YBCO熔体的生长速率增大。这一研究结果为进一步研究不同前驱坯体配置对YBCO单畴块材生长和磁通俘获性能的影响奠定了基础。2.研究了分层式前驱坯体对YBCO单畴块材的生长和磁通俘获性能的影响。使用分层式前驱坯体制备YBCO单畴块材,并对其生长形貌、磁通俘获性能以及微结构做了比较和分析。结果发现使用分层式前驱坯体由于减缓了YBCO熔体c轴方向Y~(3+)离子浓度的饱和速度,使得a-b面方向生长更加充分完全,因此制备的分层YBCO单畴块材拥有更大体积分数的c生长扇区。直径22mm分层YBCO单畴块材磁通俘获场达到0.8 T,相比于常规YBCO单畴块材的0.62 T提高了近29%。微结构分析表明分层YBCO单畴块材中Y211相粒子积聚得到了抑制,分布相对均匀,微裂痕和气孔都有所减少。3.研究了前驱坯体的优化制备高性能YBCO单畴块材。在前面工作研究结果基础上,结合溶质扩散生长模型和推出/捕获理论,利用改进的前驱坯体制备YBCO单畴块材。结果表明YBCO单畴块材内部的Y211相粒子分布得到了明显的改善。磁通俘获场得到明显的提高,直径25 mm和34 mm的YBCO单畴块材磁通俘获场峰值分别达到0.91 T(最大值0.96 T)和1.2 T(最大值1.28 T)。4.研究了Y211缓冲层对多籽晶YBCO块材畴区晶界处弱连接的影响。通过在SmBCO籽晶和前驱坯体间插入Y211缓冲层,制备了多籽晶YBCO块材,并对磁通俘获性能以及畴区晶界处的微结构做了测量。结果表明Y211缓冲层有效的抑制了多籽晶YBCO块材畴区晶界处的杂质相的残留,改善了弱连接,进而制备出磁通俘获场分布为单峰的多籽晶YBCO块材。
[Abstract]:The single domain superconducting bulk RE-Ba-Cu-O / REBCOO / REBCOO / REBCOO / REBCOO / RE-BCOO / REBCOO / RE-BCOO / RE-BCOO / REBCOO / RE-Ba-Cu / REBCO@@. Self-stabilized magnetic levitation properties and stronger flux trapping ability than ferromagnetic permanent magnets are therefore found in superconducting magnets. The field of superconducting flywheel energy storage and superconducting non-contact transmission shows great application potential, especially because of the simple and reliable preparation process of YBCO single domain bulk material, the preparation cost is relatively low. In order to further improve the magnetic flux trapping performance of YBCO single domain bulk materials, it has become the most attractive material in industrial applications. It is very important to improve the critical current and size of bulk. However, there are still some problems in the technique of preparing YBCO single domain bulk by using top seed melt texture. For example: second phase particle Y _ s _ 2BaCuO _ 5s _ s _ s _ _ _. And the weak connection at the grain boundary of single domain area of polyseed YBCO due to the residue of impurity phase. Therefore, how to solve these problems better is to improve the single domain block of YBCO. The main research goal of this thesis is to improve the flux of mono-seeded and multicrystalline YBCO bulk by solving the above problems existing in the topseed melt texture growth technology. Trapping performance. The main research contents and results are as follows:. 1. The effect of Y211 phase content on the growth of YBCO single domain bulk was studied. The precursor powder with different Y211 phase content was measured by thermal analysis and quenched growth experiment. The results show that the crystallization temperature of YBCO melts decreases with the increase of Y211 phase content. With the increase of Y211 phase content in precursor powder. The results laid a foundation for further study on the effect of different precursor body configurations on the growth and magnetic flux trapping properties of YBCO single domain bulk. 2. The effect of flooding body on the growth and flux trapping properties of YBCO single domain bulk. YBCO single domain block was prepared by stratified precursor. Its growth morphology was also studied. The magnetic flux trapping performance and microstructure were compared and analyzed. It was found that the saturation rate of ion concentration in the YBCO melt was slowed down by the use of stratified precursor. It makes the a-b plane grow more fully and completely. Therefore, the prepared layered YBCO single domain bulk has a larger volume fraction of c growth sector. The magnetic flux trapping field of 22 mm diameter layered YBCO single domain bulk is 0. 8 T. Compared with the 0.62 T of conventional YBCO single domain bulk, the microstructure analysis shows that the accumulation of Y211 phase particles in layered YBCO single domain bulk is inhibited and the distribution is relatively uniform. Microcracks and pores have been reduced. 3. The preparation of YBCO single domain blocks with high performance has been studied. Based on the results of the previous work, the solute diffusion growth model and the theory of deduction / capture have been studied. The YBCO single domain bulk was prepared from the improved precursor billet. The results show that the Y211 phase particle distribution and flux trapping field in the YBCO single domain bulk have been improved obviously. The peak value of magnetic flux capture field of 25mm and 34mm YBCO single domain bulk is 0.91T (maximum 0.96T) and 1.2T (maximum 1.28T), respectively. The influence of Y211 buffer layer on the weak connection at grain boundary of multi-seeded YBCO bulk is studied by inserting Y211 buffer layer between SmBCO seed and precursor. Multi-seeded YBCO bulk was prepared. The magnetic flux trapping performance and the microstructure at the grain boundary of the domain region were measured. The results show that the buffer layer Y211 effectively inhibits the residual impurity phase at the grain boundary of the multi-seeded YBCO bulk and improves the weak connection. Furthermore, multi-seeded YBCO bulk with a single peak magnetic flux capture field was prepared.
【学位授予单位】：上海大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：O511.3

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