Hot rolling of Bi1.6Pb0.4Sr2Ca2Cu3Ox superconducting pellets
Hot rolling of Bi1.6Pb0.4Sr2Ca2Cu3Ox superconducting pellets
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Bi1.6Pb0.4Sr2Ca2Cu3Ox超导球团的热轧
DOI：
10.1088/0953-2048/6/5/006
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发表时间：
1993
影响因子：
3.6
通讯作者：
T. K. Chaki
中科院分区：
文献类型：
--
作者：
Xiaoming Yang;T. K. Chaki
研究了Bi1.6Pb0.4Sr2Ca2Cu3Ox烧结球团在高温轧制条件下晶粒的取向。将直径12.7 mm、厚度2.5 ~ 4.5 mm的球团在预热炉中保温15 min。在两组不同的实验中使用了两个炉温，即865和880摄氏度。将热球包在ZrO2布中，在室温下在滚筒中轧制。在从炉到辊的转移过程中，球团表面的温度下降了10-15摄氏度。大约50%的厚度减少是在单次传递给球团。在扫描电子显微镜（SEM）的帮助下，在热轧球团中观察到相当大的片状晶粒排列，但由于部分熔融形成的液相在快速淬火（在轧制过程中）形成玻璃相，超导性被破坏。通过在空气中840℃退火24 h，恢复了球团的超导性。经865℃预热后退火的球团在零电阻时的超导转变温度（Tc）和77 K时的输运临界电流密度（Jc）分别为105.5+或1 K和124+或7 A cm-2，而烧结球团的超导转变温度为100.1+或0.6 K和41+或4 A cm-2。然而，在880℃加热后轧制的球团的Tc在随后的退火中仅达到60+或2 K。轧制增加了球团的密度和硬度。
Alignment of grains has been studied in sintered pellets of Bi1.6Pb0.4Sr2Ca2Cu3Ox upon rolling in hot condition. The pellets of diameter 12.7 mm and thickness 2.5-4.5 mm were kept in a pre-heated furnace for 15 min. Two furnace temperatures, namely 865 and 880 degrees C, were used in two different sets of experiments. The hot pellets were wrapped in ZrO2 cloth and rolled in a roller at room temperature. During transfer from the furnace to the roller the temperature at the surface of the pellet dropped by 10-15 degrees C. About 50% reduction in thickness was imparted to the pellets in a single pass. Considerable alignment of platelet-like grains was observed in hot-rolled pellets with the help of a scanning electron microscope (SEM), but superconductivity was destroyed due to the formation of a glassy phase upon rapid quenching (during rolling) of the liquid phase, which was formed by partial melting. By annealing the rolled pellets at 840 degrees C for 24 h in air the superconductivity was recovered. The superconducting transition temperature at zero resistance (Tc) and the transport critical current density (Jc) at 77 K of the pellets, rolled after pre-heating at 865 degrees C and subsequently annealed, were 105.5+or-1 K and 124+or-7 A cm-2 respectively, compared with 100.1+or-0.6 K and 41+or-4 A cm-2 for the sintered pellets. However, Tc of the pellets rolled after heating at 880 degrees C reached only 60+or-2 K upon subsequent annealing. Rolling increased the density and hardness of the pellets.