Basic Study Of YBCO Superconducting Tapes Prepared On The Metal Tapes

Due to its high in-field superconducting performance, high irreversible magnetic field, low AC loss and high transition temperature, YBa2Cu3O7-x (YBCO) has been taken as a hot research object. A suitable fabrication technology for industrial scale manufacturing of YBCO superconducting tapes is always a hot issue in the last several decades. The expensive apparatus of traditional physical vapour deposition technique has limited it to be used in mass production. The low efficiency of TFA-MOD method and the easy oxidation of metal tapes restrict the industrialization process for YBCO coated conductor. Therefore, to investigate and develop a fabrication approach for YBCO tape with the feature of low-cost, environmental and more practical has caused wide public concern. In this study, The low-cost technology of YBCO prepared on Ni-5at.% W (Ni5W) and Hastelloy C-276 metal tapes was studied, which could supply theoretical and technical support for the industrial mass production of YBCO superconducting tapes.La0.4Sr0.6TiO3 (LSTO) conductive buffer layer was prepared on Ni-W tapes via metal organic deposition (MOD) approach. Lanthanum acetate, Strontium acetate and tetrabutyl titanate were used as raw materials to prepare LSTO buffer layer precursor solution. The effects of heat treatment temperature and other process parameters on the epitaxial growth of LSTO buffer layer on Ni-W tapes were studied. With the technological parameters of heat treatment temperature 950?, sintering time 2h, reductive atmosphere, cooling rate 0.2?/min, and LTO seed layer precursor solution concentration 0.04mol/L, the buffer had a strong (200) cube texture, and it can provide texture template for epitaxial growth of YBCO. LSTO buffer layer possesses excellent electric conductivity, and its room temperature electric resistivity was 4.73×10-5?·m. Based on this process, well-oriented,3cm long LSTO buffer layer tape was fabricated by dip coating.The fluoride-free synthesis process of YBCO was studied. Yttrium acetate, Barium acetate, Copper acetate and propanoic acid were employed as precursor reactants to prepare fluoride-free YBCO precursor solution. It is the first time to systematically analysis the synthesis kinetics of fluoride-free YBCO in this study. The synthesis process, reaction mechanism function, activation energy, reasonable reaction time and organic decomposition time of fluoride-free YBCO had been calculated. The results showed that the activation energy was 174kJ/mol, the reasonable reaction time was 4.3h at 810?, the organic matter decomposition time was 3h at 400?.Around the oxidation problem of Ni-W tapes and its solutions, several kinds of well-oriented multi-buffer layers were prepared via MOD approach. The oxidation resistance of every kind of multi-buffer layers in the YBCO preparation process was investigated, respectively. The results showed that the oxidation resistance sequence was STO/CeO2/Ni-W<STO/LZO/Ni-W<LZO/CeO2/Ni-W< STO/LZO/CeO2/Ni-W<MOD-LZO/PLD-CeO2/Ni-W.In this study, good performance YBCO thick films were fabricated on LSTO/Ni-W and Hastelloy C-276 metal tapes by electrophoretic deposition (EPD) process for the first time. The EPD technology will open up a new manufacture process for YBCO coated conductor. Firstly, we prepared a high purity YBCO powder by chemical solution method, which could avoid the low purity and large-size particle disadvantages in traditional solid reaction sintering method. The average particle size of YBCO powder was about 1?m. The technological parameters of YBCO thick films prepared by EPD method on Ni-W tapes were discussed. With the parameters of heat treatment temperature 875?, sintering time 3h, cooling rate 1.5?/min, voltage 138V, electrophoresis time 35min, add 30mg iodine in the electrophoretic suspension, the critical current density of YBCO thick film was 1463A/cm2. Effects of suspension properties (YBCO powder concentration, deionized water concentration, additives types and amount in the suspension) on the YBCO thick film prepared on Hastelloy C-276 metal tapes were investigated. The results showed that the YBCO thick film fabricated by the suspension (the concentration of YBCO powder and deionized water was 2.0g/L and 0.005g/L, respectively, and add 0.05g PVB in suspension) possessed well superconductivity.