Optimization of fabrication conditions of MgB2/Fe superconducting tapes using response surface methodology

Abstract

We have optimized fabrication conditions of MgB2/Fe superconducting monofilament tapes fabricated using ex-situ powder-in-tube method without any intermediate annealing. Influences of three effective parameters (annealing temperature, annealing time and argon (Ar) gas atmosphere pressure during the heat treatments) on the transport critical current densities (Jc) were investigated. The samples were characterized using X-ray diffraction, scanning electron microscope, energy dispersive X-ray spectrometer, optical microscope, critical transition temperature and Jc measurements. Response surface methodology was used to optimize the conditions for the maximum Jc of the samples and to understand the significance and interaction of the factors affecting Jc. 3-level-3-factor central composite design was employed to evaluate the effects of the fabrication conditions parameters such as annealing temperatures (850–950 °C), annealing times (30–120 min.) and Ar pressures (1–5 bars) on Jc of the samples. Based on the analysis of ridge max, the optimum fabrication conditions were as follows: annealing temperature 948 °C, annealing time 58 min. and Ar pressure 3 bars.