Fe/MgB2 süperiletken teller ve parkur tipi bobinlerin üretilmesi ve incelenmesi

In this dissertation, we struggled to solve some problems of a drawing for the fabrication of various MgB2/Fe wires and improved the drawing process by employing available techniques. We produced monocore and MF (6+1 and 18+1) superconducting MgB2/Fe wires and tapes by using PIT or PLIT techniques with original initial filling process following the ex-situ or in-situ reaction routes. Then, we studied the effect of sintering temperatures, times and initial filling density on Tc, Ic, Jc, morphological/geometrical structure, densification, ρ, critical field, temperature dependence of upper critical field Bc2(T) of MgB2/Fe monocore and MF wires in various diameter produced with IA. The obtained in-situ monocore Fe/MgB2 wires with 1.90 mm and 1.00 mm diameter were sintered under argon pressure (5-10 bar) in a three-zone tube furnace at temperatures in the range of 800-900C for 1 hour to achieve superconducting property. Optimum sintering conditions to achieve better superconducting properties in terms of Jc under external magnetic field are related with monocore wire diameter. The most suitable sintering temperature for 1.90 mm wires is 900C while it is 850C for 1.00 mm wire, duration of sintering is 1 hour for both cases. Also, we studied the effect of excessive mechanical deformation by pressing under 1GPa and BP, AP and PA on the microstructure and transport properties of monocore sintered (800-1000C for 1 hour) Fe/MgB2 1.00 mm wires (cross sectional area 0.00785 cm2). The subsequent heat treatment on the Fe/MgB2 tapes (cross sectional area 0.00667 cm2) improved the microstructure and the grain connectivity. Moreover, the fabricated MgB2/Fe (18+1) MF wires with an outer diameter of 1.00 mm were sintered at temperature in the range of 700-850C for 1 hour and 2 hours under 5-10 bar argon pressure. The most convenient sintering temperature and time were found to be 700C and 1 hour in terms of achieving highest critical current value under magnetic field since the in-field Jc is one of the most important properties for superconducting materials in applications. Bending angle was examined for the monocore and MF wires in small diameters as comparison with strength wires in Bend&React process. The superconducting wires produced within this thesis were characterized using XRD, SEM, EDS, transport Jc and magnetoresistivity measurements. The results of the produced of in-situ monocore Fe/MgB2 wires as a function of the initial tube filling density indicates that increment of the initial filling density with PLIT (Filling 2) method improved the critical current of the Fe/MgB2 wires, and a high Ic (4.2 K) = 140 A at B = 5 T is achieved. The pressure of 1.1 GPa applied via HIP method increases Tc quite significantly in high magnetic field range of 6-12 T, improves the Birr and Bc2 and increases the Jc at 4.2 K and 20 K about three times. Moreover, initial filling with mixture of the amorphous boron and amorphous nano boron powders at equal amounts improved the transport engineering Jc (Ic>150 A under 3 T) values of the wires in magnetic fields (< 6 T). The excessive mechanical deformation by pressing and consecutive heat treatment improved the microstructure, the grain connectivity and transport properties of monocore sintered in-situ Fe/MgB2 wires. Finally, the in-situ MF wires were obtained by using the monocore MgB2/Fe wires which already have high Jc values under applied magnetic field and we observed that the MgB2/Fe (18+1) wires have high critical current values under low external magnetic field(< 6 T). Bending diameter size did not affect superconducting properties of the monocore and MF MgB2/Fe small diameter wires significantly in Bend&React process. Optimum sintering temperature depends on diameter of the wires. Four racetrack coils were made by winding the pieces of monocore and MF MgB2/Fe wires with about 25 meters length. The transport current of them and the produced magnetic field at the center of a racetrack coil was measured at 4.2 K.