Bi2223/Ag带材超导接头的研究

Research on Joint Between Bi2223/Ag Superconductor Tapes

采用化学法去除Bi2223/Ag带材末端的银皮,用Bi2223超导粉连接去银皮的带材,制成超导接头·然后把样品放入管式炉中进行热处理·用四引线法对接头样品进行临界电流测试:原始带材的临界电流Ic为40A,热处理后带材Ic为28A,接头处Ic为25A,这些表明已研制出超导接头·通过扫描电镜分析了接头处的断面结构,观察到接头微观结构与带材本身的微观结构有所不同,接头处的临界电流下降·对超导接头的应力、应变的力学性能测试表明,接头处力学性能要比母带材有所下降,延展性比较差·

A chemical method of making joints between Bi2223/Ag superconductor tapes was developed. At an end, the silver shield was removed from a Bi2223/Ag tape at one side surface, with that at the other side kept. Two of such tapes were contacted each other with Bi2223 powder filled in the gap to form a joint through proper heat-treatment in a tube furnace. The four-probe method was used to measure the current I_c of specimens. The I_c value of original tape is 40A and it drops to 28A after heat-treatment, and the I_c value at joint is 25A after heat-treatment. Such a result shows that a superconducting joint has been developed. The SEM images of the fracture surface of joint show that its microstructure differs to a certain extent from that of the tape itself, so that the critical current drops at the joint. The testing results of the stress/strain of the joint show that the mechanical properties of the joint is somewhat lower than that of the tapes especially its malleability.