Multi-walled carbon nanotube additive to FeSe0,5Te0,5 system to improve superconductivity properties and square core superconducting wire/tape production for engineering applications and development of coil prototype in racetrack form

The studies within the scope of this master's thesis consist of three stages. In the first stage, in the FeSe0.5Te0.5 base system, which is a member of the 11-phase belonging to the class of Fe-chalcogenide superconductors, up to 3% multi-walled carbon nanotubes are substituted for Fe positions and produced in single crystal form by self-flux method and structural, microstructural, electrical, magnetic and mechanical properties were investigated. In this context, superconductivity parameters were determined by calculating the upper critical area, Hc2, coherence length, c, activation energy, U(H,T), critical current density, Jcmag, pinning force, FP and the best superconductor was determined to be Fe1-x(MWCNT)xTe0,5Se0,5 (x=0,03). According to this result, large scale production was then carried out with Fe1-x(MWCNT)xTe0,5Se0,5 (x=0,03) stoichiometry in the second step. In the second stage, the best strip production conditions (such as heat treatment intervals, wall thickness of Fe/Ag sheaths and filling ratio) were determined by performing tests for the production of square core wire and then strip by using Fe and Ag sheaths and powder in tube method. In the last stage, Fe1-x(MWCNT)xTe0,5Se0,5 (x=0,03) superconducting strip was fabricated by producing 28,3 m long Fe/Ag/strip to prepare racetract coil prototype, and homogeneity was checked by microstructural examinations and then racetract coil production started Fe1-x(MWCNT)xTe0,5Se0,5 (x=0,03) superconducting strip, on which the necessary electrical and thermal insulation was made with compton tape and teflon tape on the prepared teflon mold, was formed into a racetract coil form by making 20 acres (winding) and electrical performance tests were carried out.