Bi_2Sr_2CaCu_2O_y超伝導体と金属銅との高温反応及びその防止

概要

論文の詳細を見る
Powders of a superconductor oxide, Bi_2Sr_2CaCu_2O_y (BSCC, 2212), were packed in a copper tube and hot-pressed in the temperature range from 500° to 800℃ for 1h under 200 kg/cm^2 aiming at fabrication of super-conducting wire using copper sheath. The reactions between the copper and the BSCC were investigated. The reaction began above 600℃, and a red-brown reaction layer of 70 μm was observed at 800℃. Powder mixtures of the oxide and copper were hot-pressed. Results of EPMA and XRD of the reaction layer showed that the 2212 phase decomposed to a 2201 phase and CuO and then to Cu_2O accompanied by the oxidation of the cop-per tube. For prevention of such reactions, electroplating of gold or silver was applied to the inner face of the copper tube. The reactions were suppressed by electroplating 20 μm of gold or 40 μm of silver. But a semiconductive temperature change of the electrical resistivity was seen for 60 μm of Ag. Finally, in the results of hot-pressing at 700℃ for 1h flowing oxygen into the tube at 1.5 kg/cm^2 using 20 μm Au or 40 μm Ag on copper, zero resistance was not shown for Au-electroplating, but it was obtained at 22K for the Ag-plating. Thus, a possibility of fabrication of copper sheath wire with silver-plating holding oxygen pressure in the copper tube during an extrusion or a hot-pressing process was confirmed.
社団法人日本セラミックス協会の論文
1992-11-01