This article is a survey of the processes for making β-W type structure superconducting compound materials. These processes are classified as follows:
(1) Diffusion process: V
3Ga is easily formed by a improved diffusion technique at 700°C. Nb
3Sn and V
3Si are formed by the diffusion treatment around 950°C while the formation of Nb
3Ga and Nb
3Al requires much higher diffusion temperatures.
(2) Chemical vapour deposition process: Nb
3Sn, V
3Si and Nb
3Ga are deposited by the hydrogen reduction of mixed chloride gases of the constitutional elements.
(3) Vacuum vapour deposition process: Nb
3Sn is made by the simultaneous vapour deposition of Nb and Sn in high vacuum. Processing of high
Tc compound Nb
3(Al
0.8Ge
0.2) is also being studied.
(4) Plasma spray process: Nb
3Sn coil can be made directly by this process without wire windings.
High field superconducting Nb
3Sn tapes have already been made commercially by the process (1) and (2). V
3Ga tape also seems to be promising for practical use.
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