Superconducting magnetic resonance imaging (MRI) and superconducting nuclear magnetic resonance spectrometer (NMR) require the superconducting magnet to operate in closed loop in order to obtain high stable magnetic fields. Therefore, the connection between the coil and the coil in the superconducting magnet, and the connection resistance between the coil and the superconducting switch are required to be very small. For MRI devices, joint resistance is reported to be less than 10-11 ohms; For NMR devices the joint resistance is less than 10-14 ohms.
The invention relates to a method for making niobium-titanium superconducting joint, which comprises steps:
a) The stable copper or aluminum matrix at the end of niobium-titanium (NbTi) composite superconducting wire is removed by acid corrosion to form a niobium-titanium (NbTi) superconducting wire, which is dried by inert gas after cleaning to prevent oxidation;
b) Select several superconducting wires treated in step a as needed, and twist and weave the superconducting wires of several superconducting wires together;
c) The twisted end of the superconducting wire is inserted into the cold-pressed tube through the horn of the conical section of the niobium-titanium (NbTi) cold-pressed tube, and protruded from the other end through the straight tube section;
d) The niobium-titanium (NbTi) cold-pressed tube is combined with the niobium-titanium (NbTi) cold-pressed tube by applying pressure on the straight tube section;
e) The combined niobium-titanium (NbTi) superconducting wire (2) and niobium-titanium (NbTi) cold-pressed tube are placed into the copper tube and filled with solder;
f) After heating, melt the solder, cool and bond at room temperature to obtain the finished product.
