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c Conductors: The Alloy Nb–Ti
Published in David A. Cardwell, David C. Larbalestier, Aleksander I. Braginski, Handbook of Superconductivity, 2023
Lance D. Cooley, Peter J. Lee, David C. Larbalestier
Niobium-titanium alloys have been widely used in superconducting applications since the early 1960s. The success of Nb–Ti has been due to its combination of excellent strength and ductility with high current-carrying capacity at magnetic fields sufficient for most applications. Moreover, these advantages are obtained with raw material and fabrication costs that are significantly lower than other technological superconductors for magnetic fields in the 2–8 T range. A significant factor driving down the cost is the widespread use of Nb–Ti in magnetic resonance imaging (MRI) magnets, which amounts to a consumption of approximately 1000 tons per year of finished Cu and Nb–Ti, strand. Another unique advantage of Nb–Ti superconductors is the fact that heat treatments that form flux-pinning centres can be applied prior to cabling, winding and other magnet assembly steps. This is made possible by the lack of any strong dependence of the superconducting properties on strain and by the mechanical toughness of Nb–Ti strands. High yield strength, comparable to that of steels [1], further relaxes constraints on the support structure. These excellent properties will ensure continued widespread use of Nb–Ti alloys for a long time to come. Primary applications of Nb–Ti alloy superconductors include magnets for MRI, nuclear magnetic resonance (NMR), laboratory apparatus, particle accelerators, electric power conditioning, minesweeping, ore separation, levitated trains and superconducting magnetic energy storage (SMES).
Energy Storage
Published in Mukund R. Patel, Omid Beik, Wind and Solar Power Systems, 2021
In the superconducting energy storage system, a major cost is to keep the coil below the critical superconducting temperature. Until now, the niobium–titanium alloy has been extensively used, which has a critical temperature of about 9°K. This requires liquid helium as a coolant at around 4°K. The 1986 discovery of high-temperature superconductors has accelerated the industry interest in this technology. Three types of high-temperature superconducting materials are available now, all made from bismuth or yttrium–cuprate compounds. These superconductors have the critical temperature around 100°K. Therefore, they can be cooled by liquid nitrogen, which needs significantly less refrigeration power. As a result, numerous programs around the world have started to develop commercial applications. Toshiba of Japan, GEC-Alsthom along with Electricite de France, and many others are actively pursuing development in this field.3,4
Localized Electric Generation Applications Overview
Published in Neil Petchers, Combined Heating, Cooling & Power Handbook: Technologies & Applications, 2020
One favored superconductor for storage applications is a niobium-titanium alloy, which needs to be kept at liquid helium temperature in order to superconduct. Higher-temperature superconductors (i.e., those that operate at liquid nitrogen temperature or above) are not considered technically advanced enough to be considered for large-scale application. Market development continues based on the premise that once SMES has established a foothold in the utility market based on conventional superconductors, high-temperature superconductors can be introduced to reduce capital and operating costs once their physical characteristics have improved and the manufacturing processes are more mature.
Mechanical properties of micro-alloyed steels studied using a evolutionary deep neural network
Published in Materials and Manufacturing Processes, 2020
Swagata Roy, Bhupinder Singh Saini, Debalay Chakrabarti, Nirupam Chakraborti
It is seen that the optimum results predicted for EvoNN, BioGP, and EvoDN2 are more or less within the range of objectives in dataset itself with the exception of UTS predicted which, for BioGP and EvoDN2, often surpassed the limit in data and have predicted quite high UTS values. EvoNN converged in a small range of UTS while EvoDN2 has provided diverse range. For CVN and Elon, EvoDN2 is the only algorithm to get Pareto optimal results with maximum output. EvoDN2, EvoNN, and BioGP have given more or less same range of composition for each elements and also they are all in the range in data sheet. Some variables as predicted should be very less in amount; e.g. phosphorus, niobium, titanium, etc. This is because these elements were present minutely in the data used for Charpy energy. Overall composition predicted can be used to make alloys with high UTS, elongation and Charpy energy. As seen before, EvoDN2 has predicted a very high value of UTS for some composition while some compositions with low output are also obtained. Some of the Pareto points worth mentioning are shown in Table 3.
Effects of Fiber Diameter and Tribotest Conditions on Nonlubricated Frictional Behavior of a Microsized Metal Fiber
Published in Tribology Transactions, 2018
Jun Wang, Xingyi Zhang, Jun Zhou, You-He Zhou
Friction tests were conducted on six fibers of NbTi with diameters of 22.9, 34.9, 53.7, 62.2, 79.8, and 115.0 μm, which were extracted from the commercial multifilamentary superconducting composite strands consisting of niobium–titanium filaments in a copper matrix (NbTi/Cu). The PVC is formed by injection molding technology. The surface roughness of the PVC cylinders is Ra = 0.4 μm. Ra is an arithmetic average height parameter. A schematic of the frictional experiment of a microsized NbTi fiber around a PVC cylinder shown in Fig. 1. The PVC cylinder is fixed and the NbTi fiber slides around the cylinder. A weight (initial tension force: ) is hung at one end of the fiber and the other connects a force sensor, which is linked by a material testing machine. By controlling the movement of the testing machine, the sliding speed of the fiber around the PVC cylinder can be controlled, and the real-time tension force () can also be recorded. The weight (initial tension force: ) in the experiment is weighed by a balance with an accuracy of 0.01 g. The maximum scale of the force sensor is 300 g, with an accuracy of 0.02%. All experimental parameters are listed in Table 1. It should be noted that all experiments are carried out with an invariable velocity (acceleration is zero) at room temperature without lubrication; the fiber weight is ignored in this study.
Synthesis and degradation behaviour of Zn-modified coating on Mg alloy
Published in Surface Engineering, 2021
Jun Wang, Chaoyang Jin, Di Mei, Yan Ding, Lei Chang, Shijie Zhu, Liguo Wang, Yashan Feng, Shaokang Guan
Zn has been found as a beneficial element for the healing of fractures, along with strontium and fluorine [15–17]. Zn exerts important effects on the preservation of bone mass by stimulating osteoblastic bone formation and inhibiting osteoclastic bone resorption. Zn deficiency may cause skeletal growth retardation, prolonged bone recovery [18–20]. However, few studies have focused on Zn-modified calcium phosphate coatings on magnesium substrates. Zn-modified calcium phosphate coatings have been fabricated on niobium, titanium and pure iron substrates via phosphation [21,22], plasma electrolytic oxidation [23], and pulsed electro-deposition [24]. The bioactivity of Zn-modified calcium phosphate coatings on pure iron and titanium have been previously proven [21,23,24]. Furko et al. [20] have reported that pulse electrodeposited Zn substituted HAp on Ti6Al4 V can improve corrosion resistance and enhances biological properties. However, since the dual inhibition effect of Mg2+ and Zn2+ on the crystallization of calcium phosphate, Zn-modified calcium phosphate coating is not easy to be fabricated on Mg alloy. Zeng et al. [25] have tried to fabricate Zn–Ca phosphate coating on Mg–Li–Ca substrates via phosphation. However, the morphology of obtained coating is ununiform and incompact, which restricts the performance of the coating. Dual-pulse electrodeposition has been regarded as an effective approach to fabricate the uniform Ca–P coating on Mg alloy [8]. Thus, it is worthy for fabricating the Zn-modified calcium phosphate on Mg alloys via electrodeposition which is probably beneficial for obtaining a compact and uniform coating.