DEVELOPMENT OF IN-SITU FABRICATION PROCESS OF COLUMNAR YBCO/Ag COMPOSITES

单方向固体YBCO的超导体和机械性能是由Ag Addition改进的。However，在大气层中形成了许多气体洞，在YBCO/Ag复合材料中熔化/固体。在YBCO/Ag复合材料中熔化在真空中，以减少大气层中的气体洞和固体，形成了Ag粒子丰富区域，靠近样品的中心区域。这些Ag颗粒和气体孔改变了复合材料的热行为和有效温度梯度在样本中的作用。Ag粒子和气体洞的分布已被测量，热条件和效应温度梯度已被估计为应用混合规则中的变化。在G>A·R的关键固体条件下开发了123列YBCO/Ag复合体晶体，其中A=6*10^5， G为温度梯度（K/cm），R为固体速率（mu m/s）。对没有Ag的YBCO来说，更高的关键条件比这一点（A=4*10^5）要困难得多（因为干扰桶） ... More 在123个接口上的Ag粒子的影响。Ag粒子在123个界面上变得更大，并且在123个阶段中被困，当它们超过临界尺寸时..。在单元格的中心区域，由从界面推Ag粒子形成Ag-free区域。123个蜂窝面接口的晶体学方向已被测量，每个接口的正常增长率（Ri）已被估计为细胞尖端的痕迹，其中被上方的无区检测到：Ri （001） = 0.47R-0.61R，Ri （100） =Ri （010） = 0.62R-0.70R，在123个阶段被捕获的Ag粒子的临界半径（下），在ro和the growth rate （Ri） of faceted planes was given by the equation ： Ri=b/ro， where b= 1. 05。进一步，YBCO/Ag联接的接口抗性（rho c）由固态和液态处理制成，并且最低rho c低于约10^<-12> OMEGA·m^2在两个案例中发现，并确定复合导体的稳定性标准。Less（低）

Superconducting and mechanical properties of unidirectionally solidified YBCO are improved by Ag addition. However, many gas holes formed in YBCO/Ag composites melted/solidified in the atmosphere. In YBCO/Ag composites melted in a vacuum to reduce the gas holes and solidified in the atmosphere, Ag particle-rich zone formed near the central region of the sample. These Ag particles and gas holes changed thermal conductivity of composite and the effective temperature gradient in the sample. The distributions of Ag particles and gas holes were measured and the changes in thermal conductivity and the effective temperature gradient were estimated by applying the rule of mixtures. 123 columnar crystals in YBCO/Ag composites developed under the critical solidification condition of G>A・R,where A=6*10^5, G was temperature gradient (K/cm), and R was solidification rate (mu m/s). The above critical condition is a little harder than that (A=4*10^5) for YBCO without Ag, because of the diffusion barr … More ier effect of Ag particles at the 123 interface. Ag particles became larger at the 123 interface by the monotectic reaction and were trapped within 123 phase when they exceeded a critical size.. At the central region of the cell, Ag-free zones formed by pushing Ag particles from the interface. The crystallographic orientations of 123 cellular facet interfaces were measured, and the normal growth rate (Ri) of each interface was estimated from the trace of the cell tip, which was detected by the above Ag-free zones : Ri (001) =0.47R-0.61R,and Ri (100) =Ri (010) =0.62R-0.70R.From the measured critical radius (ro) of Ag particles trapped in the 123 phase, the relationship between ro and the growth rate (Ri) of faceted planes was given by the equation : Ri=b/ro, where b=1.05. Further, the interface resistivities (rho c) of YBCO/Ag joints fabricated by solid state processing and liquid state processing were measured, and the minimum rho c as low as about 10^<-12> OMEGA・m^2 was obtained in both cases, which satisfied the stability criteria for composite conductors. Less