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George C.,Indian Institute of Technology Madras | George C.,The Tech Magnet | Chandrakumar N.,Indian Institute of Technology Madras
Chemical Physics Letters | Year: 2015

We report a novel diagonal suppressed two-dimensional total correlation experiment in solution state and demonstrate its performance in 1H and 2H NMR. In DIagonal Suppressed spin echo TOtal Correlation SpectroscopY (DISTOCSY), diagonal peaks which occur around F1 = 0 in spin echo mode are removed by conversion to unobservable multiple quantum or longitudinal terms in each scan of a two scan procedure, on application of an appropriately phased 90° pulse at the time of the echo maximum. The limitation of this approach to short FID acquisition times is discussed, and an alternative two-scan version of DISTOCSY for high resolution situations is presented. © 2015 Elsevier B.V. All rights reserved.

Isotahdon E.,Tampere University of Technology | Huttunen-Saarivirta E.,Tampere University of Technology | Kuokkala V.-T.,Tampere University of Technology | Paju M.,The Tech Magnet
Materials Chemistry and Physics | Year: 2012

In this work, the corrosion behaviour of seven Nd-Fe-B magnets was studied. The differences between the studied magnet grades were the fabrication route and the contents of total rare-earth (TRE) elements and cobalt. Studies consisted of microstructural characterization, electrochemical corrosion tests, and highly accelerated stress tests (HAST). In the scanning electron microscope (SEM) studies of the polished magnets, three phases were identified: the matrix phase, Nd-rich phase, and Nd-oxide. Electrochemical tests performed were electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements. The results from polarization measurements and HAST tests were consistent. Magnets with cobalt addition and low TRE content showed the lowest corrosion current densities and the highest corrosion potentials in polarization measurements and experienced the lowest weight losses in HAST tests. Therefore, cobalt and TRE contents were considered as eligible parameters for the estimation of the corrosion resistance of sintered Nd-Fe-B magnets. © 2012 Elsevier B.V. All rights reserved.

Agency: Cordis | Branch: FP7 | Program: CP-TP | Phase: NMP.2012.4.1-2 | Award Amount: 4.97M | Year: 2013

The REMANENCE concept is to develop new and innovative processes for the recovery and recycling of rare earth (RE) containing neodymium iron boron magnets (NdFeB) from a range of waste electronic and electrical equipment (WEEE). Advanced sensing and mechanical separation techniques combined with innovative processes based on hydrogen decrepitation will recover the rare earth magnets in the WEEE. Significantly with the REMANENCE concept, the aim will be to recover material in a form that can easily re-enter the primary magnet manufacturing production route, so providing large energy savings and production costs. There is no existing process for the recovery of NdFeB magnets from waste streams and this highly valuable material is lost to land fill with no prospect of commercial recovery. The material recovered in the REMANENCE concept will have a substantial economic value, which considering current virgin material costs, is estimated to be 80-120 per kg. If fully implemented REMANENCE will provide a secondary source of materials for the EU, large enough to supply the entire EU bonded magnet manufacturing industry and a significant proportion of the EUs high value sintered magnet production. REMANENCE brings together Europes leading experts in; sensing, disassembly, recycling technology and materials processing with a group of innovative SMEs in a multi-disciplinary project able to deliver significant technical advances. The key technical roles of the SMEs as either equipment manufacturers (CTECH, OPTI, ABI) or direct end users of the recovered materials (MAG) will focus the project towards commercial outputs that will result in excellent exploitation opportunities for the developed processes.

Wozniak M.,The Tech Magnet | Hale H.,The Tech Magnet
IEEE Transactions on Applied Superconductivity | Year: 2016

MgB2 opens the door to viable, cryogen-free, and thermally stable MRI magnets. A multiturn multilayer MgB2 solenoid coil was tested in a variable temperature environment from 5 to 34 K in order to validate the conductor's long-length critical current and n-value performance. The reacted wire was successfully wound and impregnated without imparting noticeable strain damage to the MgB2 filaments as demonstrated by the consistency between measured long-length wire performance of the coil and the short sample data. Expected coil performance was calculated by taking into account ferromagnetic wire matrix and critical current scaling based on current percolation model. © 2002-2011 IEEE.

Haavisto M.,The Tech Magnet | Kankaanpaa H.,Neorem Magnets Oy | Paju M.,The Tech Magnet
IEEE Transactions on Magnetics | Year: 2011

The thermal stability of sintered NdFeB magnets can be described by the temperature coefficient of remanent flux density α only on condition that demagnetization due to rising temperature or field and oxidation of the magnets are totally avoided. This also requires the control of time-dependent demagnetization at elevated temperatures. We have studied the time-dependent polarization losses in sintered NdFeB magnets with different coercivities by determining temperature T0 for each magnet (Pc = 1.1). T0 is the maximum temperature at which the total polarization loss even after 30 years of exposure is estimated to be less than 2%. Temperature T0 for four magnets produced from different materials are presented in this work. Flux losses at temperatures higher than T0 after different exposure times are also described. The estimated flux loss after 30 years is found to be roughly twice the loss after 1 h, except in the vicinity of T0. At temperature T0 +10 °C , it could be as high as four times the loss after 1 h. © 2006 IEEE.

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