A recycling process for degraded aged bare bulk (Bi, Pb)-2223 tubes – Revival of (Bi, Pb)-2223 phase and superconducting properties

• Reported first time a process for recycling of Bi-2223 current leads.
• The Bi-2223 is the degraded aged bare tubes of large size.
• Comparative analyses of the two recycling methods (RS, RP) are presented.
• The RP method leads to detainment of the superconducting properties.
• This study gives the possibility of reusing the bare degraded heavy recycled Bi-2223.

Bare bulk tube superconducting current leads (CLs) of (Bi, Pb)2 Sr2 Ca2 Cu3 O10+x: 10 wt% Ag (Length = 410 mm, outer diameter = 45 mm, and inner diameter = 42 mm) have been found to show a degradation in the normal state affecting the superconducting properties due to ageing of the material. These reference samples (named as RF) have been studied over a period of five and ten years. A decomposition of the Bi-2223 phase has been observed after testing several times during the period affecting normal state and superconducting properties considerably. An attempt has been made in order to obtain reusable product using two recycling methods. In one of the methods, these degraded samples were re-sintered (named as RS) and in the second one, they were reprocessed (named as RP). Those is, in the second method, the steps of crushing, mixing, calcining, cold isostatically pressing into tubes, making silver current contacts at both end portions of this tube and finally of sintering were followed to make reprocessed bare bulk tube current leads. Both these RS and RP samples were sintered under identical conditions as those of the conditions used for the RF samples. Comparative analyses of the two recycling (RS and RP) methods with respect to normal state and superconducting state properties are also presented.