The Doping Effects of SiC and Carbon Nanotubes on the Manufacture of Superconducting Monofilament MgB_2 Wires

摘要

MgB_(2) superconductor is a superconductor with a critical temperature of around 39K and has the potential to replace Nb_(3)Sn and NbTi as superconducting coils to produce high magnetic fields. In this study, monofilament wires have been made to analyze the doping effect of SiC and Carbon Nanotubes (CNT) in its manufacture using Powder-In-Tube (PIT) method. Stainless Steel (SS-316) tube was used as a tube filled with powders of starting materials of Mg, B, SiC and CNT. A total of 8 samples were prepared with variations in the addition of SiC, and CNT as much as 5, 10, and 15 wt %, and also the variations in the addition of Mg composition by 0 and 10 mol % from normal stoichiometric values. The samples were rolled and sintered at 800°C for 3 hours. The samples then were analyzed using SEM (Scanning Electron Microscopy) to analyze the surface morphology, XRD (X-Ray Diffractometer) to analyze the formed phases and crystal structures, and then resistivity versus temperature using cryogenic systems to analyze their superconductivity properties. Based on the results of the XRD analysis, the MgB_(2) phase is the major phase in the samples and the SiC doping causes the formation of minor phases of Mg_(2)Si and Fe_(3)C. The addition of SiC causes a decrease in crystalline properties of the MgB_(2) phase due to reaction with SiC, while the addition of CNT does not cause the formation of a new phase. Based on the results of the analysis of resistance versus temperature, it is seen that the addition of SiC causes a decrease in T_(C) value. While the addition of CNT causes the improvement in the nature of superconductivity, but it also causes the decrease of its T_(C )values.