焊接技术是高温超导带材实际应用中的关键技术,焊接温度、焊料、搭接长度等工艺环节对带材接头性能都有一定的影响.本文针对高温超导一代Bi2223/Ag带材和二代YBCO带材的接头焊接工艺进行了系统的实验研究,包括焊接温度对带材性能的影响、不同焊料及搭接长度对接头性能的影响等.实验结果表明:一代Bi2223/Ag高温超导带材在400~C焊接温度以内载流能力不会发生明显退化,而二代YBCO带材对温度较敏感,在200℃以上带材性能会出现明显退化;在Bi2223/Ag及YBCO带材各自的焊接温区内,不同焊料对带材接头性能有一定的影响,但液氮温度下接头电阻均能达到10-8 Ω量级,其临界电流与带材短样相比无太大变化;两种超导带材的接头电阻均与焊接搭接长度成反比,适当增加焊接搭接长度可以减小接头电阻,提高带材接头性能.
Soldering technique is the key to high-temperature superconducting tapes in the practical application. All of the heating temperature, the solder and the contact length of soldering zone have an impact on the performance of the joint. Based on it, a systematic experimental study was carried out about the soldering technique of tapes. The experimental results show that the current carrying capacity of Bi2223/Ag will not have significant degradation under 400℃, while the performance of YBCO will be degraded above 200℃ because of its sensitivity to temperature. Different solder has a certain impact on the performance of the joints in the respective soldering temperature region of Bi2223/Ag and YBCO. The joint resistances can be controlled at the level of 10-8Ω at 77K and the critical current has little change compared with the short samples. There is an inverse relationship between the contact length of the soldering zone and joint resistance. The increasing of the contact length of soldering zone could reduce the joint resistance and improve the performance of the soldered joint.