We have investigated the effect of addition of Al2O3 in the manufacture of the BPSCCO superconductors using solid state reaction method. Precursors with consist of Bi2O3, PbO2, SrCO3, CaCO3, and CuO powders were ground using mortar agate for 3 h. The samples were heated at 300°C for 6 h to remove the moisture in the powders, and then ground again for 6 h. Then the samples were calculated at 820°C for 20 h and then Al2O3 (1wt% and 2wt%) were added and ground again. The powders were compacted with a diameter of 10 mm and a thickness of 2 mm and then sintered at 850°C for 30 h. The characterizations were carried out by using Cryogenic Magnet to determine the superconductivity properties, SEM-EDX to analyze the morphology and XRD to determine the phase formed. The resistivity versus temperature results showed the increase of Tc with the addition of Al2O3. Sample with 1wt% Al2O3 has Tconset of 90 K and Tczero of 66 K, when the sample with 2wt% Al2O3 has Tconset of 94 K and Tczero of 73 K. The morphology formed looks less homogeneous, the crystalline granules are melt-shaped, clumpy and there are porosity.

MgB2 superconductor is a superconductor with a critical temperature of around 39K and has the potential to replace Nb3Sn 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 MgB2 phase is the major phase in the samples and the SiC doping causes the formation of minor phases of Mg2Si and Fe3C. The addition of SiC causes a decrease in crystalline properties of the MgB2 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 TC value. While the addition of CNT causes the improvement in the nature of superconductivity, but it also causes the decrease of its TC values.

Penelitian ini bertujuan untuk mempelajari korosi pada baja galvanis setelah diekspos di Sungai Cidaho Wilayah Sukabumi, Jawa Barat. Kehilangan berat baja galvanis diukur dengan metode pengurangan berat setelah diekspos untuk periode waktu tertentu di permukaan air sungai dan kedalaman air 1 meter. Morfologi permukaan dan komposisi produk korosinya dianalisis menggunakan Scanning Electron Microscopy (SEM) -Energy Dispersive Spectroscopy (EDS) dan X-Raya Diffraction (XRD). Setelah diekspos, seluruh permukaan baja galvanis tertutup oleh produk korosi. Hasil berat yang hilang dari baja galvanis setelah diekspos 76 hari adalah 1,37 mg/cm 2 pada permukaan air sungai dan 7,83 mg/cm 2 untuk kedalaman air 1 meter. Peningkatan kerusakan dari baja galvanis ini terjadi karena tidak terbentuk lapisan protektif akibat tergerus arus sungai. Produk korosi yang dominan pada baja galvanis yang diekspos pada kedalaman 1 meter adalah senyawa Zincite (ZnO). Hasil ini mengindikasikan bahwa penggunaan baja galvanis tidak cocok untuk lingkungan di kedalaman air.

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