排序方式: 共有28条查询结果,搜索用时 46 毫秒
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G.M. Polli L. Reccia A. Cucchiaro A. della Corte A. Di Zenobio L. Muzzi A. Pizzuto G. Ramogida S. Turtú R. Villari M. Nannini C. Portafaix L. Zani P. Barabaschi 《Fusion Engineering and Design》2009,84(7-11):1531-1538
In the framework of the Broader Approach Agreement, Europe is involved in the design activities for the Japanese Tokamak JT-60SA, investigating, among several issues, the operation of the superconducting TF magnets and their subsystems, aimed at the reactor conceptual design definition. In particular, one of the main critical aspects to study is the heating of the conductor due to both direct component of energy deposited by neutrons and by secondary gamma generated during plasma operation, and heat generated by the radiation on casing and transferred to the winding pack. Indeed, the operating temperature and the relevant temperature margin (i.e. the operating safety margin) of the magnet will depend strongly on the heat loads and on the capability of the coolant to remove it. Furthermore, the heat power to the conductor will depend on several aspects, namely the thickness of insulating material, the mass flow rate of helium flowing in the conductors and its thermodynamic properties at operating conditions, and the layout of the superconductors constituting the winding. Moreover, a crucial aspect in the final design will be the presence and position of the casing cooling channels. In this paper a 2D sensitivity analysis of heat transfer from casing to winding pack with respect to cooling channels number and position is presented, based on the reference layout of the magnet. As a result, we evaluated the optimum number and positioning of cooling channels needed, as a trade-off between magnet operating limits and available cryogenic power and if, at limit, they could be even neglected in normal operation, keeping dwell-time within reasonable values. 相似文献
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《Canadian Metallurgical Quarterly》2013,52(3):249-253
AbstractCompression tests on a commercial three-phase aluminum bronze showed significant softening above the β transformation. This was not observed in either beryllium-copper or α/β brass above their transformation temperatures. Isothermal compression tests on the aluminum bronze showed some rate sensitivity and there was no significant change in either mechanical properties or microstructure after large strains at the elevated temperature. These characteristics are typical of superplastic alloys.Closed-die forging experiments in which a thin tapered lip was backward extruded on a cylindrical billet have shown that the material forges adequately at low pressures at temperatures above the transformation. It was concluded that creep forging of this aluminum bronze gives good die filling and surface finish. Résumé On a observé un adoucissement significatif d'un bronze à l'aluminium commercial (contenant trois phases) lorsque déformé en compression au-dessus de la transformation β. Le phénomène n'a pas été observe dans le cuivre au beryllium et le laiton α+β déformés au-dessus de leur temperature de transformation. Des essais de compression isotherme sur le bronze à l'aluminium ont permis d'observer une certaine sensibilité au taux de déformation; après de grandes déformations à la température élevée, les propriétés mécaniques et la microstructure n'ont pas été modifiées appréciablement. Ce comportement est typique des alliages superplastiques.Des essais de forgeage en matrice ferme, au cours desquels une mince lèvre effilée a été extrudée, d'une manière inverse, sur une billette cylindrique, ont montré que de faibles pressions sont suffisantes pour forger le matériau adéquatement lorsqu'on opère à des températures au-dessus du point de transformation. Les auteurs ont conclu que le forgeage de fluage permet de bien remplir la cavite et d'obtenir un bon fini de surface. 相似文献
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Jia Li Qingrong Yao Weichao Huang Jue Xie Zhilin Mo Jianqiu Deng Jiang Wang Guanghui Rao Huaiying Zhou 《中国稀土学报(英文版)》2022,40(5):784-791
New energy vehicles and offshore wind power industries have a high demand for sintered Nd–Fe–B magnets with high intrinsic coercivity and high corrosion resistance. In this study, the magnetic properties, anticorrosion properties, and microstructure of Nd–Fe–B sintered magnets with the intergranular addition of low-melting-point eutectic Tb68Ni32 alloy powders were investigated. The aim is to determine if the addition of Tb68Ni32 can improve these properties. A low melting-point eutectic alloy Tb68Ni32 powders was prepared as a grain boundary additive and blended with the master alloy powders prior to sintering. The coercivity of the resultant magnets gradually increases from 1468 to 2151 kA/m by adding increasing amounts of Tb68Ni32. At the same time, the remanence first increases and then slightly decreases. After studying the microstructure and elemental composition of the Tb68Ni32 added magnets, it is found that the significant increase in coercivity and the negligible reduction in remanence is due to densification, improved grain orientation, a uniform and continuous boundary phase distribution, as well as the generation of a (Nd,Pr,Tb)2Fe14B “core–shell” structure surrounding the main-phase grain. Moreover, the corrosion resistance of the magnet is greatly improved owing to the enhancement of electrochemical stability, as well as the optimization of the distribution and morphology of the intergranular phase. 相似文献
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Solid state chlorination with NH4Cl as chlorinating agent represents a new way for rare earth recovery from end‐of‐life‐magnets. Compared to hydrometallurgical recycling approaches this process provides a number of economic advantages. As a first step, solid state chlorination was adjusted with disused FeNdB magnets from a wind power plant. The SE yield of the chlorination step was optimized according to a 33‐Box‐Behnken design with varying temperature, time, and NH4Cl/magnet ratio. Likewise, the process profits from leaching with a sodium acetate/acetic acid buffer following the chlorination step. 相似文献
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