High temperature insulation coatings and their electrical properties for HTS/LTS conductors

Abstract

The high temperature compatible insulation coatings were produced using solutions of Zr, Mg, Y, Ce, Er, Sm, In, Sn, Sr, Pb, Ba, Al, and La based organometallic precursors using a non-vacuum sol–gel technique. The growth mechanism and microstructure of these coatings was characterized using environmental scanning electron microscopy and X-ray diffraction. Dielectric constants and breakdown voltages of these coatings were also measured by using an insulation tester. The results of microstructure and electric properties of these coatings are presented. The oxide structures were formed between temperatures of 450 and 550 °C from amorphous coating. MgO–ZrO 2 coatings on Ag and AgMg sheathed Bi-2212 tapes have been used as the insulation for the 1 T and 3 T HTS high field insert coil. These ceramic insulation coating can be built up to ∼10 μm by successive dipping. Crack-free, dense, very thin (submicron) coatings were also obtained using different solvent and acid with the same method with appropriate dilution of solutions.