Contact Resistance Properties of Cold-Pressing Superconducting Joints

A NbTi superconducting joint technology applied for MRI/NMR has been developed with a cold-pressing method. The plastic deformation microstructure of the fabricated joint was investigated by using scanning electron microscopy and optical microscope. The joint resistances were tested using coil current decay method. The contact resistance properties of the superconducting joint were investigated. The evolution of plastic deforming and the electrical contact characteristics of the NbTi superconducting joint are discussed. It is believed that the contact resistance is composed of constriction resistance and film resistance. With the pressure increasing, the dominant factor is changed from the film resistance to the constriction resistance. Finally, the joint resistance is inversely proportional to the cubic root of applied pressure. The joint resistance correlates with the increase in plastic deformation with increased pressure.