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 Bi₂Sr₂Ca₁Cu₂O_x (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 Bi-2212 wires and tapes at 500 °C for 2 min in air using a reel-to-reel, continuous sol-gel technique and these tapes were subsequently annealed at ∼ 860 °C 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 °C and thin film thickness increases with number of dipping operations. The average adhesive strength of ZrO₂ was found to be 0.763 MPa.