Novel nano-composite bulk superconductors for high field engineering applications

用于高场工程应用的新型纳米复合体超导体

• 批准号: EP/H049657/1
• 负责人: David Cardwell
• 金额: $ 57.32万
• 依托单位: University of Cambridge
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2010
• 资助国家: 英国
• 起止时间: 2010 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FH049657%2F1
• 关键词: Novel; nano; composite; bulk; superconductors

Multi-specimen combinations of large, melt processed YBCO single grains of 25 mm diameter have been shown to trap stable magnetic fields as high as 17 T at 29 K in research-grade samples, which are simply not achievable in conventional iron-based permanent magnets (limited practically to less than ~ 1.5 T). Unfortunately, achieving and maintaining a bulk, superconducting device operating temperature of less than 65 K is difficult from a practical point of view and not particularly cost-effective. It is necessary, therefore, to develop materials with improved flux pinning (and hence field trapping) properties that can be fabricated economically for deployment in industrial applications based either on cryo-cooler technology, or on systems that use liquid nitrogen as a cryogen (boiling point, 77 K). Large single grains can be incorporated directly into existing sustainable engineering applications such as flywheels, magnetic bearings, permanent magnets for MRI/NMR, non-contact magnetic stirrers for high purity biological solutions and magnetic separators provided they can trap at least 2.0 T at 77 K. The closer the operating temperature to the transition temperature of the large single grain (typically ~ 90 K), however, the greater the requirement for effective artificial flux pinning centres in the large grain microstructure that prevent the motion of magnetic flux within the sample. The optimum size of such pinning centres is typically around a few nano-metres at 77 K. The most common method of introducing pinning centres into large YBCO grains involves engineering the size of Y2BaCuO5 (Y-211) phase inclusions in the bulk microstructure, which are produced as part of the Y-123 peritectic decomposition process during melt processing. The technique is limited fundamentally, however, by the tendency of Y-211 particles to ripen at elevated temperature, which conflicts directly with attempts to refine their size to the nano-scale. This results inevitably in a significant reduction in control of the melt process, and hence to limitations in sample performance. The PI has been involved in two important recent developments of the processing of large grain (RE)BCO superconductors. These are the development of a suitable non-211 phase that forms effective nano-scale artificial flux pinning centres, and in the development of an entirely new type of seed crystal that enables every member of the (RE)BCO class of materials to be grown in the form of large single grains by a practical techniques for the first time. The primary objective of this highly challenging project, therefore, is to fabricate mechanically stable, large, state of the art samples of single grain YBCO and other (RE)BCO melt processed superconductors than has been possible previously that contain novel (i.e. non Y-211-based), effective nano-scale artificial flux pinning centres by a practical processing technique. This will enable for the first time the cost-effective application of bulk superconductors in sustainable engineering devices that operate at, or around, 77 K. Additional objectives of this challenging proposal are to fabricate complex-shaped, new nano-phase composites for be-spoke applications for the first time using a novel multi-seeding technique, also underdevelopment at Cambridge by the PI, and to establish for the first time an effective recycling process for multi-grain samples. The project will involve extensive collaboration with four Cambridge science departments (Engineering, Materials Science, Physics and Chemistry) and with three international institutions (ATI Vienna, ICMAB Barcelona and the Boeing Company Seattle).

已显示，直径为25 mm的大型熔融YBCO单晶粒的多种特异性组合已显示可在研究级样品中捕获高达17 t的稳定磁场，在研究级样品中，在基于常规的铁的永久磁铁中根本无法实现（实际上限制在实际上小于〜1.5 t）。不幸的是，从实际的角度来看，难以实现和维持批量，超导器件的工作温度小于65 K是很困难的，并且不是特别有效。因此，有必要开发具有改进的通量固定（以及现场捕获）特性的材料，这些材料可以经济制造，用于基于低温冷却器技术的工业应用，或使用使用液氮作为低温器（沸点，77 K）的系统。可以将大型单晶粒直接纳入现有的可持续工程应用中，例如飞轮，磁轴承，用于MRI/NMR的永久磁铁，非接触式磁性搅拌器，用于高纯度生物学解决方案和磁性分离器，只要它们可以在77 k处捕获至少2.0 t。大谷物微观结构，可防止样品中磁通量的运动。这种固定中心的最佳尺寸通常约为77 K的几个纳米米。将固定中心引入大型YBCO谷物的最常见方法涉及在bulk微结构中工程Y2BACUO5（Y-211）相结合的大小，这些方法是在Y-123 Perectic Decomportic Process中产生的Y2BACUO5（Y-211）含量。然而，从根本上讲，该技术受到Y-211颗粒在升高温度下成熟的趋势的趋势，这与试图将其大小完善到纳米级的尝试直接冲突。这不可避免地会大大减少对熔体过程的控制，从而导致样本性能的局限性。 PI参与了大谷物（RE）BCO超导体加工的两个重要发展。这些是合适的非211阶段的开发，该阶段形成有效的纳米级人造通量固定中心，并且在开发一种全新的种子晶体中，该晶体可以通过实用的技术以大型单个晶粒的形式生长（RE）BCO BCO类材料类别的每个成员。因此，这个高度挑战性项目的主要目的是制造机械稳定的单粒YBCO和其他（RE）BCO熔体处理的超导体的最先进的样本，而不是以前可能包含新颖的（即基于Y-211）的新型，有效的纳米尺度人工量化的固定中心，该中心通过实用的处理技术。这将在首次实现在可持续工程设备中或周围运行的可持续工程设备中的成本效益的应用。这项具有挑战性的提议的其他目标是为第一次使用新型的多种新型技术来制造复杂形状的，新的纳米相复合材料，用于首次使用新型的循环范围，以供PIY和cams cam cam cam pi，用于首次使用新型型号，并使用新型的纳米相复合材料。用于多粒样品。该项目将涉及与四个剑桥科学系（工程，材料科学，物理和化学）以及三个国际机构（Ati Vienna，Icmab Barcelona和波音公司西雅图）的广泛合作。

项目成果

A trapped field of > 3T in bulk MgB_ fabricated by uniaxial hot pressing

单轴热压制备块状 MgB_ 中 > 3T 的俘获场

• 期刊: Superconductor Science and Technology
• 影响因子: 3.6
• 作者: David Cardwell (Author)

YBCO single grains seeded by 45° - 45° bridge-seeds of different length.

YBCO单粒种子采用45° - 45°不同长度的桥粒播种。

• 期刊: Superconductor Science and Technology
• 影响因子: 3.6
• 作者: David Cardwell (Author)

Properties of grain boundaries in bulk, melt processed YB2Cu3O7-_ fabricated using bridge-shaped seeds

使用桥形晶种制造的块状、熔融加工 YB2Cu3O7-_ 的晶界特性

• 期刊: Superconductor Science and Technology
• 影响因子: 3.6
• 作者: David Cardwell (Author)