Niobium based intermetallics as a source of high-current/high magnetic field superconductors

Abstract

The article is focused on low temperature intermetallic A15 superconducting wires development for Nuclear Magnetic Resonance, NMR, and Nuclear Magnetic Imaging, MRI, magnets and also on cryogen-free magnets. There are many other applications which would benefit from new development such as future Large Hadron Collider to be built from A15 intermetallic conductors. This paper highlights the current status of development of the niobium based intermetallics with special attention to Nb 3 (Al 1-x ,Ge x ). Discussion is focused on the materials science aspects of conductor manufacture, such as β-phase (A15) formation, with particular emphasis on the maximisation of the superconducting parameters, such as critical current density, J c , critical temperature, T c , and upper critical field, H c2 . Many successful manufacturing techniques of the potential niobium-aluminide intermetallic superconducting conductors, such as solid-state processing, liquid-solid processing, rapid heating/cooling processes, are described, compared and assessed. Special emphasis has been laid on conditions under which the J c (B) peak effect occurs in some of the Nb 3( Al,Ge) wires. A novel electrodeoxidizing method developed in Cambridge whereby the alloys and intermetallics are produced cheaply making all superconducting electromagnetic devices, using low cost LTCs, more cost effective is presented. This new technique has potential to revolutionise the existing superconducting industry enabling reduction of cost orders of magnitude.

Novel electrochemical measurements on direct electro-deoxidation of solid TiO2 and ZrO2 in molten calcium chloride medium

“…The half cell potential measurements with the reference electrode showed that the anodic potential remained at 1.5-1.6 V and the cathodic potential at *-1.5 V throughout stage 2 of the electro-deoxidation process. This confirmed that the positive deviation of the anodic and cathodic potentials in stage 2 of the galvanostatic experiment under discussion is attributable to the change of the reference electrolyte composition, and hence the transition of the electrode reaction from (15) to (17) as discussed above. The results of the ongoing studies of electro-deoxidation of TiO 2 using the new reference electrode will be discussed in detail elsewhere.…”

“…When electrons are passed into the metal oxide from an external power source, the oxygen present in the metal oxide combines with the electrons and leaves the cathode as oxygen ions which discharge at the graphite anode and liberate CO/CO 2 gas. The process was demonstrated for production of many metals [6][7][8][9][10][11][12], semi-metal [13,14] and alloys [15][16][17][18][19]. We have also investigated the electro-deoxidation behaviour of zirconium dioxide in the process [20].…”

Chemical and Electrochemical Processing of Aluminum Dross Using Molten Salts

“…[17] Many metal oxides and metaloxide mixtures have also been successfully reduced to their metals and alloys based on the cathodic oxygen ionization using molten CaCl 2 -based chlorides. [18][19][20][21][22][23][24][25][26][27][28][29][30] Little work has been published in the literature on direct electrochemical reduction of solid Al 2 O 3 and AlN in molten salts.…”

Electrodeposition of Nb and Al from chloroaluminate melt on vitreous carbon

“…Niobium's specific characteristics like corrosion resistivity, superconductivity, thermostability and biocompatibility, make it very interesting basic or added component for alloys. Niobium alloys are successfully applied in electronic, automotive, nuclear and space industry, but also in medical aids and implants productions [1][2][3].…”