Mechanical and superconducting properties of nanosize MgO added dip-coated Bi&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;Sr&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;CaCu&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;O&amp;lt;sub&amp;gt;8&amp;lt;/sub&amp;gt; superconducting tape

Nasri A Hamid,Noor Fairuz Shamsudin,Mohd Yusri Abd Rahman

doi:10.4236/ns.2011.36067

Abstract

In this work, 3% to 8% (in weight) of nanosize MgO particles was added to Bi2Sr2CaCu2O8 (Bi- 2212) high-temperature superconductor to fab-ricate Bi-2212 superconducting material with superior mechanical properties. The mechanical strength of the samples was studied by con-ducting the compression test at room tempera-ture, and the addition of 5% nanosize MgO par-ticles produced the highest strength when com- pared with other samples. The sample with 5% MgO addition also exhibited superior super-conducting properties. The Bi-2212 powder with 5% nanosize MgO addition was used to fabricate Bi-2212 tapes through the dip-coating-then- stacking method. The fully processed tapes were investigated via dc electrical resistance measurements, XRD patterns, SEM micrographs, transport critical current density and tensile tests. The tensile tests were conducted at room and cryogenic (77 K) temperatures. Results of tensile tests and Young’s modulus for the tapes showed that the Bi-2212 tapes with nanosize MgO addition recorded better mechanical prop-erty compared to the non-added samples both at room and cryogenic temperatures. The double- core tape with 5% MgO addition recorded the highest failure point at 160 MPa. In addition to the strengthening effect that was observed in the nanosize MgO added Bi-2212 superconduc-tor tapes, the superconducting properties re-mained intact in the tapes.

Highlights

For practical applications of high-temperature superconductor materials in power engineering, where thermo-mechanical and electromagnetically induced stresses are expected to occur, the high-temperature superconductor materials need to have excellent superconducting properties and higher mechanical strength
MgO fibers have been used to reinforce Bi-2212 superconductor and are able to improve the mechanical properties of the compounds [4,5]
The addition of nanosize MgO particles has shown to be an effective pinning center for Bi-2212/MgO compounds and samples with nanocrystalline microstructures are found to exhibit better plasticity under stress compared with samples of larger grains [6,7,8,9,10]

Summary

INTRODUCTION

For practical applications of high-temperature superconductor materials in power engineering, where thermo-mechanical and electromagnetically induced stresses are expected to occur, the high-temperature superconductor materials need to have excellent superconducting properties and higher mechanical strength. The Bi-2212 superconductor, like other Bi-based high-temperature superconductors is generally has poor mechanical properties such as low stiffness, strength and toughness despite their excellent superconducting properties [1,2,3,4]. MgO fibers have been used to reinforce Bi-2212 superconductor and are able to improve the mechanical properties of the compounds [4,5]. There is no specific report that focuses on the mechanical strength of single-core and doublecore dip-coated Bi-2212 superconducting tapes with nanosize MgO addition both at room and cryogenic temperatures. Throughout this study, the tapes were fabricated using the dip-coating--stacking (DIS) method [11]

EXPERIMENTAL PROCEDURES

RESULTS AND DISCUSSIONS

CONCLUSIONS