Using high-temperature superconductors for levitation applications

Melt-textured, bulk high-temperature superconductors are finding increasing uses in superconducting bearings, flywheel energy storage, and other levitational applications. This article reviews the use of these materials in magnetic-levitation applications. The behavior of levitational force, stiffness, damping, and rotational losses is discussed. For more information, contact J.R. Hull, Argonne National Laboratory, ET-335, Argonne, Illinois 60439; (630) 252-8580; fax (630) 252-5568; e-mail jhull@anl.gov.     

Perspectives of elementary technologies for AC power applications of high temperature superconductors

To apply high temperature superconductors (HTS) to AC power apparatuses, R&Ds for AC loss reduction and quench protection of HTS wires are as important as R&Ds for high performance HTS wires. Perspectives of elementary technologies for the AC loss reduction and quench protection are presented in the paper.     

Beta-titanium alloys and prospects of their development

A classification of β-titanium alloys based on a structural factor and reflecting the special features of physical, mechanical, and technological properties of each group is suggested. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 12, pp. 11–14, December, 1998.     

Multiphase anodic layers and prospects of their application

Information on preparing multiphase layers on valve metals by the plasma-electrochemical oxidation and deposition from aqueous electrolytes containing polyphosphate and fluoride metal complexes, iso-and heteropolyoxoanions, as well as electrolytes evolving solid precipitates, is summarized. Possible application fields of the metal/multiphase PEOD surface structure compositions are considered. Original Russian Text ? V.S. Rudnev, 2008, published in Zashchita Metallov, 2008, Vol. 44, No. 3, pp. 283–292.     

High-energy NdFeB magnets and their applications

In sintered NdFeB magnets, additive elements for increasing coercivity decrease residual magnetization. Also, fine magnetic powder oxidization prevents identification of the stoichiometry composition (Nd ₂Fei₁₄B).To improve the magnetic properties of a sintered NdFeB magnet, the authors have developed a method involving two alloys. Magnetic Nd ₂Fei₁₄Balloy and a rare- earth- rich alloy (including richer dysprosium content) are melted individually and mixed together after coarse pulverization. After the sintering process, dysprosium in the sintered body is enriched in each grain region near the grain boundary. The two- alloy method minimizes the liquid phase necessary to keep the coercive force at a useful level, and thus results in compositions closer to stoichiometry. The energy product of magnets having an inhomogeneous dysprosium distribution is typically 360 kj - m ^{- 3} (45 MG.Oe) at production level. The corrosion characteristics of cobalt- substituted NdFeB magnets also were investigated. These magnets are now used in voice coil motors for hard disk drives and contribute to shortening access time and hard- drive downsizing.     

Polyaniline doped with orthophosphoric acid—A material with prospects for optoelectronic applications

Polyaniline (PANI) is one of the highly pursued conducting polymers in recent times owing to its excellent electrical and optical properties, better air stability and easy and cheap synthesis route. Doped PANI has been extensively investigated as a hole-injecting electrode in polymer light emitting diodes (LEDs). However, the work on doped PANI as emissive layers in polymer LEDs is quite scanty. Though there are reports on the photoluminescence characteristics of doped PANI, a detailed investigation on a comparative study of the photo luminescence in PANI doped with different dopants, which is the essence of our work, has not been carried out earlier. In the present work, we compare the photoluminescence (PL) emission intensity of PANI doped with hydrochloric acid (HCl), camphor sulphonic acid (CSA) and orthophosphoric acid, with a view to assessing the prospects of doped PANI as emissive layer in polymer LEDs. The PL emission peak is centered around 450 nm when excited at 365 nm. PANI doped with orthophosphoric acid exhibits the highest photoluminescent intensity followed by PANI doped with HCl and CSA. A comparison of the X.R.D spectra of the samples show that both HCl doped PANI and CSA doped PANI, do not show any significant crystalline nature whereas orthophosphoric acid doped PANI exhibits considerable crystallanity. The observed long-range order in orthophosphoric acid doped PANI could be a consequence of the more orderly arrangement of benzenoid and quinonoid units, resulting in enhanced PL emission intensity.     

Study on the electronic structures of REBaCuO superconductors and their relation to superconductivity

Electronic structures of REBaCuO(RE=La,Pr,Nd,Sm,Gd,Dy,Ho and Er) systems were calculated by means of SCF-Xα-SW methods.Results show that there is an inner-orbit coupling for these oxide superconductor systems.The inner-ordit coupling was resulted from the interaction of two electronic orbits of RE 5p and O 2s,since they have similar energy state levels and relatively larger orbital electronic clouds.Compared with experimental facts,it is also found that the overlap in space between the two orbits has a similar tendency to Tc and the number of enrolling electrons has a close relation to Jc,therefore,the influence of inner-ordit coupling on superconductivity could not be overlooked.     

The potential applications for titanium metal powder and their life cycle impacts

It has been predicted that new processes being developed for titanium metal production as well as new fabrication techniques will see the cost of fabricated titanium fall by as much as 50%. Potential applications for lower-cost titanium powder are examined in this paper, with cookware, being identified as a possible lead product. The potential environmental benefits of using this material in place of competing materials such as stainless of competing materials such as stainless steel in chemical process equipment and automotive exhausts are also illustrated, based on a life-cycle approach.     

杆系结构的回弹变分原理及其应用

本文引入了杆系结构的回弹反耦联系统和回弹反耦联方程的概念。应用加权余量法于回弹反耦联方程, 建立了杆系结构的回弹势能原理和回弹余能原理。应用表明, 回弹变分原理为求解杆系回弹变形提供了一个新的途径。     

原位生长碳纳米管及其在SiC_f/SiC复合材料中的应用

采用碳纳米管改善纤维与基体间的界面结合,同时利用碳纳米管自身的优异性能对碳化硅纤维增强碳化硅复合材料(SiCf/SiC)进行二次增强。通过化学气相沉积工艺(CVD)在SiC纤维编织件内原位生长碳纳米管,优化碳纳米管原位生长过程中的碳源流量、反应温度和反应时间等工艺参数,对碳纳米管的原位生长工艺及机理进行系统分析,并结合先驱体浸渍裂解工艺(PIP)制备CNTs-SiCf/SiC复合材料,探讨原位生长碳纳米管的引入对复合材料力学性能的影响。结果表明,优化后的工艺参数如下:反应温度750℃,C2H2、H2和N2流量比1/1/3,C2H2流量100~150 mL/min,反应时间60 min;碳纳米管的引入使SiCf/SiC复合材料的弯曲强度、弯曲模量和断裂韧性分别提高了16.3%、90.4%和106.3%。     

复合塑性成形新技术及其应用

介绍了几种复合塑性成形新技术,包括热锻冷锻复合技术、板料冲压冷锻复合技术、以及结合铸造和锻造特点开发出来的铸造锻造技术和半固态成形技术,以及它们在工业生产中的应用情况。