Influence of Ag-Au and Ag-Cu alloys on Bi2Sr2CaCu2Ox superconductor

Abstract

The influence of Ag-Au and Ag-Cu alloy substrates on the microstructure and superconducting properties of Bi2Sr2CaCu2Ox (Bi-2212) was studied. The critical current density (Jc) of Bi-2212/(Ag-Au) was not degraded by increasing the Au content of the Ag-Au alloy, while the Jc of Bi-2212/(Ag-Cu) was drastically degraded by increasing the Cu content of the Ag-Cu alloy. The microstructure of Bi-2212 on the Ag-Au alloy was uniform and no precipitates were observed. The Jc degradation of Bi-2212 in contact with the Ag-Cu alloy was understood by the fact that Cu absorption of Bi-2212 from the Ag-Cu alloys changed the composition of the oxide layer. Ag-Au alloys are superior substrate materials for Bi-2212 for power current leads for superconducting magnets, taking into account their low thermal conductivity.

Fabrication of (Ba,K)Fe2As2tapes byex situPIT process using Ag-Sn alloy single sheath

“…Double sheaths of Fe/Ag [25], Cu/Ag [26], Ni/Ag [21] and stainless steel (SUS)/Ag [27] have been examined, and we showed that the SUS/Ag double sheath is a very effective way of improving the microstructure and enhancing the J c properties [27]. Another possible method is alloying another element to the Ag, as extensively studied for Ag-clad BiSrCaCuO superconductors [28][29][30]. In this work, we examined the alloying of Sn to a pure Ag sheath of ex situ PIT-processed (Ba,K)Fe 2 As 2 (Ba-122) tape and investigated its influence on the microstructures and superconducting properties.…”

Low thermal conductive Bi-2223 tapes sheathed with Ag-Au alloys

“…ing characteristics of Bi2S5CaCu20x (Bi-2212) ,thick films on these alloy substrates prepared by the doctor blade method [7] and Bi2Sr2Ca2Cu,0x (Bi-2223) superconducting tapes sheathed with the same alloys [8] were previously investigated. The Ag-Cu alloys reacted with the Bi-basedtsuperconductors and caused degradation of the superconducting characterislics.…”

Thermal conductivity of silver alloy stabilizers for high temperature superconductor current leads

“…The AgAu alloy was proposed as a stabilizer [3] because it weakly influences the superconducting characteristics of the HTS; but, the AgAu alloy has poorer mechanical characteristics than Ag and, since a high amount of gold should be added in order to decrease the thermal conductivity [1], the use of it dramatically increases the cost. Actually, thermal and electrical properties of Ag alloys have not been systematically evaluated [4][5][6][7], and, according to a recent study [5], the AgMg alloy shows a thermal conductivity much lower than the AgAu one, as well as better mechanical properties.…”