JOINING OF UNIDIRECTIONALLY SOLIDIFIED SUPERCONDUCTING OXIDE AND SILVER AND EVALUATION OF ITS INTERFACE CHARACTERISTICS

对123阶段（YBa_2Cu_3O_<7-X>）的银和Y-Ba-Cu-O超导电氧化物（YBCO）低抵抗力连接的两种制造方法进行了调查，其中一种是从液体+211 （Y_2BaCuO_5）阶段获得的单向固体合成。其中一种方法是通过热媒进行固体状态处理，以建立固体银/YBCO联合，在没有可检测的交互层形成的。通过四个探测方法去除加入温度（T）或加入压力（P）中的增加，在77 K处测量了接口抵抗力（rhoc） ，并得出最低值：rhoc=2*10^<-12>OMEGA·m^2在P= 32 MPa、T= 873 K、t= 3600的情况下被捕获，另一种方法是通过使用熔融银处理的液体状态。在那个引人注目的反应层是在界面上形成的。自从反应被123个阶段的分解转化为液体+211，反应层被缓慢冷却和太阳恢复到123个阶段。 ... More idification。在这种情况下， rhoc被回收治疗所破坏，最低值低于约10^<-12>OMEGA·m^2，符合复合线的稳定标准的哪些。进一步，研究YBCO基底的结构控制，123柱晶体的增长机制已经分析，通过液体+211的一个事实接口，通过液体中的渗透反应与溶液中的扩散。根据123柱晶体增长动力学分析： R=（Ca/eta）·{（ML·DELTATpc+ DELTACc）/（Tp/m_<L123>+Cf·Tp/m_<L211>）}^2，Ca和Cf是常数， eta是粘度， ML=1/m_-1/<L123>m_<L211>，m_和m_相对于123柱晶体增长率的斜率，m_<L123>和m_相对于123和211的液体斜率<L211>，DELTACrc是由211个粒子表面能量在123个冻结的前端引起的变化。这一关系与实验结果一致。123晶体从柱体到均衡结构的转变通过使用R-DELTATpc关系和实验性Uncooling（DELTATp）对123晶体体的核进行了充分模拟。Less（低）

Two fabrication methods were investigated to develop the low resistivity joints of silver and Y-Ba-Cu-O superconducting oxide (YBCO) with the columnar crystal structure of 123 phase (YBa_2 Cu_3O_<7-X>) , which was obtained by unidirectional solidification from liquid+211 (Y_2BaCuO_5) phases. One of the methods was a solid state processing by the hot-press to make solid silver/YBCO joint, in which no detectable interaction layr was formed. The interface resistivity (rhoc) at 77K measured by the four-prove method decreased with the increase in joining temperature (T) or joining pressure (P) , and the minimum value : rhoc=2*10^<-12>OMEGA・m^2 was obtained when the joining conditions were P=32MPa, T=873K,t=3600s.Another method was a liquid state processing by using molten silver, in which the remarkable reaction layr was formed at the interface. Since the reaction was caused by the decomposition of 123 phase to liquid+211, the reaction layr was recovered to 123 phase by slow cooling and sol … More idification. In this case, rhoc remarkably decreased by the recovering treatment, and the minimum value was as low as about 10^<-12>OMEGA・m^2, Which satisfied the stability criteria for composite wire. Further, to study the structure controll of YBCO substrate, the growth mechanism of 123 columnar crystal was analyzed, which grew with a facet interface from liquid+211 through a peritectic reaction with solute diffusion in the liquid. The following relation was conducted between 123 growth rate (R) and undercooling (DELTATpc=Ti-Tp, Ti : interface temperature, Tp : peritectic temperature) by the analysis of kinetics for 123 columnar crystal growth : R=(Ca/eta)・{(ML・DELTATpc+DELTACrc)/(Tp/m_<L123>+Cf・Tp/m_<L211>)}^2, where Ca and Cf are constants, eta is the viscosity, ML=1/m_<L123>-1/m_<L211>, m_<L123> and m_<L211> are respectively the slope of liquidus of 123 and 211, DELTACrc is the change in equilibrium solute concentration caused by the surface energy of 211 particle at the 123 freezing front. This relation agreeed well with the experimental results. The transition of 123 crystals from columnar to equiaxd structure was successfully simulated by using the above R-DELTATpc relation and the experimental undercooling (DELTATp) for the nucleation of 123 crystals. Less