Low resistivity joints for joining wires and methods for making the same

Abstract

Method for joining wires using low resistivity joints is provided. More specifically, methods of joining one or more wires having superconductive filaments, such as magnesium diboride filaments, are provided. The wires are joined by a low resistivity joint to form wires of a desired length for applications, such in medical imaging applications.

1 . A method of joining wires, comprising:
 introducing a magnesium diboride joint material to an end of a first wire and an end of a second wire at a joint area, wherein at least one of the first and second wires comprises superconductive magnesium diboride filaments; and   affecting the joint area such that the end of the first wire and the end of the second wire are electrically and mechanically coupled through the joint material.   
   
   
       2 . The method, as set forth in  claim 1 , wherein each of the first and second wires comprises superconductive magnesium diboride filaments. 
   
   
       3 . The method, as set forth in  claim 1 , wherein the first wire comprises magnesium diboride filaments and the second wire comprises filaments that do not comprise magnesium diboride. 
   
   
       4 . The method, as set forth in  claim 3 , wherein the filaments of the second wire are superconductive. 
   
   
       5 . The method, as set forth in  claim 1 , wherein affecting the joint area comprises at lease one of a mechanical process, a thermal process, a chemical process or combinations thereof. 
   
   
       6 . The method, as set forth in  claim 1 , wherein affecting the joint area comprises deforming the joint area to densify the filaments of each of the first and second wires and the magnesium diboride joint material. 
   
   
       7 . The method, as set forth in  claim 1 , wherein affecting the joint area comprises heating the joint area to sinter the filaments of each of the first and second wires and the magnesium diboride joint material. 
   
   
       8 . The method, as set forth in  claim 1 , wherein affecting the joint area comprises at least one of evaporation, sublimation or volatilization, or combinations thereof. 
   
   
       9 . The method, as set forth in  claim 1 , wherein affecting the joint area comprises at least one of swaging, rolling, drawing, extruding or isopressing, or combinations thereof. 
   
   
       10 . The method, as set forth in  claim 1 , wherein affecting the joint area comprises at least one of solid-state sintering, liquid phase sintering, annealing, melting or diffusion bonding, or combinations thereof. 
   
   
       11 . The method, as set forth in  claim 1 , wherein affecting the joint area comprises at least one of radiation, convection, induction, resistance, laser treatment or electronic beam treatment, or combinations thereof. 
   
   
       12 . The method, as set forth in  claim 1 , comprising:
 preparing the end of a first wire; and   preparing the end of the second wire, before introducing the magnesium diboride joint material.   
   
   
       13 . The method, as set forth in  claim 12 , wherein preparing the ends of the first and second wires comprises stripping a cladding material to expose an extended portion of the filaments of each of the first and second wires. 
   
   
       14 . The method, as set forth in  claim 1 , wherein the magnesium diboride joint material is doped. 
   
   
       15 . The method, as set forth in  claim 1 , wherein introducing a magnesium diboride joint material comprises disposing a composite material comprising magnesium diboride and at least one other material on the joint area. 
   
   
       16 . The method, as set forth in  claim 15 , wherein the at least one other material comprises a superconductor. 
   
   
       17 . The method, as set forth in  claim 1 , wherein introducing a magnesium diboride joint material comprises introducing a solid joint material having bore holes formed therein, and wherein the method further comprises:
 stripping the ends of each of the first and second wires to expose an extended portion of the filaments of each wire; and   inserting the extended portion of each of the filaments of each of the wires into the bore holes.   
   
   
       18 . A method of joining superconductive wires comprising:
 preparing an end of a first wire in a mateable configuration, wherein the first wire comprises superconductive magnesium diboride filaments surrounded by a conductive cladding;   preparing an end of a second wire in a mateable configuration, wherein the second wire comprises superconductive magnesium diboride filaments surrounded by a conductive cladding;   mateably joining the end of the first wire to the end of the second wire; and   surrounding the mateably joined end of the first wire and the end of the second wire in a wrapping material.   
   
   
       19 . The method of joining superconductive wires, as set forth in  claim 18 , wherein:
 preparing an end of a first wire comprises removing a portion of the conductive cladding to provide an extended portion of the superconductive magnesium diboride filaments; and   preparing an end of a second wire comprises forming a bore hole in the superconductive magnesium diboride filaments at the end of the second wire.   
   
   
       20 . The method of joining superconductive wires, as set forth in  claim 19 , wherein mateably joining the end of the first wire to the end of the second wire comprises inserting the extended portion of the superconductive magnesium diboride filaments of the first wire into the bore hole in the superconductive magnesium diboride filaments at the end of the second wire. 
   
   
       21 . The method of joining superconductive wires, as set forth in  claim 18 , wherein surrounding the mateably joined end of the first wire and the end of the second wire in a wrapping material comprises surrounding the end of the first wire and the end of the second wire in a material configured to provide mechanical strength, a diffusion barrier, or an electrical quench medium, or combinations thereof. 
   
   
       22 . The method of joining superconductive wires, as set forth in  claim 18 , further comprising heating the mateably joined end of the first wire and the end of the second wire. 
   
   
       23 . A superconductive wire comprising:
 a first wire segment having superconductive filaments comprising magnesium diboride;   a second wire segment having superconductive filaments comprising magnesium diboride; and   a low resistivity joint coupling the first wire segment to the second wire segment, wherein the persistent joint comprises magnesium diboride.   
   
   
       24 . The superconductive wire, as set forth in  claim 23 , wherein the low resistivity joint has a resistance through the joint of less than or equal to 10 −8  ohms/cm 2 . 
   
   
       25 . The supreconductive wire, as set forth in  claim 23 , wherein the low resistivity joint comprises a very low resistivity joint having a resistance through the joint in the range of approximately 10 −8  ohms/cm 2  to approximately 10 −13  ohms/cm 2 . 
   
   
       26 . The supreconductive wire, as set forth in  claim 23 , wherein the low resistivity joint comprises a persistent joint having a resistance through the joint of less than or equal to 10 −13  ohms/cm 2    
   
   
       27 . The superconductive wire, as set forth in  claim 26 , wherein the first wire segment comprises doped magnesium diboride filaments and the second wire segment comprises doped magnesium diboride filaments. 
   
   
       28 . The superconductive wire, as set forth in  claim 26 , wherein the low resistivity joint comprises magnesium diboride in a powder form. 
   
   
       29 . The superconductive wire, as set forth in  claim 26 , wherein the low resistivity joint comprises magnesium diboride in a liquid form. 
   
   
       30 . The superconductive wire, as set forth in  claim 26 , wherein the low resistivity joint comprises a composite of magnesium diboride and at least one other material. 
   
   
       31 . The superconductive wire, as set forth in  claim 30 , wherein the at least one other material comprises a superconductive material. 
   
   
       32 . The superconductive wire, as set forth in  claim 31 , wherein the superconductive material comprises at least one of Nb 3 Sn, NbTi, YBCO, BiStCaCuO, TlBaCaCuO, or HgBaCaCuO. 
   
   
       33 . The superconductive wire, as set forth in  claim 30 , wherein the at least one other material comprises a non-superconductive material. 
   
   
       34 . The superconductive wire, as set forth in  claim 33 , wherein the superconductive material comprises at least one of Nb 3 Sn, NbTi, YBCO, BiStCaCuO, TlBaCaCuO, or HgBaCaCuO. 
   
   
       35 . The superconductive wire, as set forth in  claim 30 , wherein the at least one other material comprises a resistive material. 
   
   
       36 . The superconductive wire, as set forth in  claim 35 , wherein the resistive material comprises solder. 
   
   
       37 . The superconductive wire, as set forth in  claim 26 , wherein the low resistivity joint comprises one of a butt joint, scarf joint, lap joint, bridle/box joint, bridge joint or telescoping joint. 
   
   
       38 . The superconductive wire, as set forth in  claim 26 , wherein the low resistivity joint is surrounded by a conductive cladding. 
   
   
       39 . The conductive wire, as set forth in  claim 26 , further comprising at least one heat sink proximate to the low resistivity joint.