Development of multi-turn reel-to-reel crystallization large furnace for high production rate of YBa2Cu3Oy coated conductors derived from TFA–MOD process

YBa 2 Cu 3 O y (YBCO) coated conductors were fabricated by trifluoroacetates (TFA)–metal organic deposition (MOD) previously using a single reel-to-reel (RTR) crystallization furnace with a gas flow system parallel to the tape surface which could realize only a low production rate. In this study, we developed a new multi-turn (MT) RTR furnace with a vertical gas flow system to increase the production rate of the crystallization step and attained the uniform reaction in the tapes of the multi-turn system. We fabricated YBCO films with different conditions partial pressure of water vapor, the total pressure and the gas flow volume using the MT-RTR furnace with the vertical gas flow system, in order to investigate the influence of the processing parameters on the growth rate and the superconducting properties of the YBCO films. It was found that the growth rate of the YBCO phase film increased under the conditions of the high gas flow rate, the low total pressure and the high water vapor partial pressure. As a result, 21 times higher J c value was attained at 17 times faster growth rate than that without controlling the processing parameters in the crystallization step. This is thought to be due to the suppression of coarsening of Y 2 Cu 2 O 5 and CuO particles in the precursor film. Consequently, the high I c,end-to-end value of 250 A was achieved in a 5 m long tape fabricated at the production rate of 3 m/h using the only two lanes of the entire MT-RTR crystallization furnace with 10 lanes.