Synthesis and characterization of high temperature compatible ZrO2 insulation coatings on Ag/AgMg sheathed Bi-2212 wires and tapes

High temperature compatible ZrO2 insulation coatings have been successfully fabricated on Ag and AgMg sheathed Bi2Sr2Ca1Cu2Ox (Bi-2212) superconducting wires and tapes for high magnetic field magnets. Solutions were prepared from a zirconium based organometallic compound, solvent and chelating agent. The ZrO2 was coated on Ag and AgMg sheathed Bi2212 wires and tapes at 500 degreesC for 2 min in air using a reel-to-reel, continuous sol-gel technique and these tapes were subsequently annealed at similar to860 degreesC in a flowing oxygen atmosphere. The relationship between the solutions and the coatings was evaluated. With reference to environment scanning electron microscope, energy dispersive spectroscopy, differential thermal analysis, thermogravimetric and X-ray diffraction studies, different steps in the process leading to the formation of ZrO2 are discussed. These studies indicate that the formation of cubic ZrO2 starts at approximately 450-550 degreesC and thin film thickness increases with number of dipping operations. The average adhesive strength of ZrO2 was found to be 0.763 MPa. (C) 2002 Elsevier Science B.V. All rights reserved.