Er2O3 insulation coatings on Ag/AgMg sheathed Bi-2212 superconducting tapes by sol-gel process

We have fabricated high temperature insulation coatings on long-length superconducting tapes and wires using a reel-to-reel sol-gel dip coating system for HTS/LTS coils at NHMFL. In this work, 8 mol% Er2O3 -ZrO2 coatings were deposited on Ag or AgMg sheathed Bi2Sr2Ca1Cu2Ox (Bi-2212) superconducting tapes. The insulation solution was prepared with Zr and Er based organometallic compounds. The gel layers were transformed to amorphous layers at about 300 degreesC for 30 see. in air. The ceramic oxide coatings were subsequently formed at 600 degreesC for 60 sec. in air. The coatings on Ag/AgMg sheathed Bi-2212 tapes were finally densified by annealing at 862 degreesC for 12 h under oxygen gas flow. These coatings were characterized by means of ESEM, DTA, and XRD. Dielectric constant, breakdown voltage and resistance values of the coatings were measured using a standard multimeter and power supply. ESEM revealed that surface morphology of the coatings is mosaic structure. XRD and DTA studies show that cubic phases formed at between 450 degreesC and 600 degreesC. Dielectric constant, high voltage breakdown and resistance values of the insulations were found to be 20, 1096 V at 1.5 mA and 14 M-Ohms, respectively.