Liquid Phase Diffusion Bonding of High Temperature Superconducting Ceramics

为了发展既保持机械强度又保持超导性能的连接方法，采用了包晶温度比YBCO低的YbBCO（Yb 123）作为中间层，添加Ag 2 O作为中间层，对YBCO（Y123）超导块材进行了连接。在这项研究中的连接方法的概念是基于这样一个事实，即Yb 123的形成温度（TP）是约50 K低于Y123。在1293 K（高于Y123的TP）加热10 min，然后缓慢冷却至1198 K，接头的显微组织显示，Y元素从基体向连接层扩散，Yb从连接层向基体扩散，连接部分变得更加致密。作为在添加到YbBCO中的Ag 2 O含量为0 ~ 44质量%并且接合温度为1213 K ~ 1293 K的条件下的接合试验的结果，接合强度随着接合温度的升高而增加。当YbBCO中间层中添加10 ~ 30 mass%Ag2O时，临界电流密度出现最大值;由于接头处存在空洞，接头强度低于基体，但通过选择连接时间和压力条件可以提高接头性能。研究结果表明，采用Yb_（123）中间层可以改善Y_123块材的连接性能。

In order to develop joining methods maintaining mechanical strength and superconducting property, YBCO(Y123) bulk superconductors were joined using YbBCO(Yb123), which had lower peritectic temperature than YBCO, added Ag2O as interlayer. The concept of the joining method in this study is based on the fact that the peritectic formation temperature(TP) of Yb123 is about 50K lower than that of Y123. The Samples were heated at about 1293K(above TP of Y123) for 10 minutes and slowly cooled down to 1198K.The microstructures of the joints revealed that Y element diffused from the bulk to the joining layers and Yb diffused from the joining layers to the bulk, and the joining part seemed to become more dense. As results of joining tests under such conditions that Ag2O content added to YbBCO was 0〜44 mass % and that joining temperature was 1213K 〜1293K, the joint strength increased in accordance with the joining temperature increase. Critical current density showed maximum value in case using the YbBCO interlayer added 10〜30 mass %Ag2O.Because of the boids occurred at the joint area, strength of the joint was inferior to that of the matrix, however, it was suggested that joint properties could be improved by selecting the joining time and pressure conditions. The possibility to improve the joining property of Y123 bulk was shown by use of Yb123 interlayer.