Andika Widya Pramono

Macrocellular vitreous carbon with the improved mechanical strength

Vitreous carbons with regular macrocellular structure, open interconnected porosity, high specific strength and hydraulic permeability were synthesized by infiltration of the epoxy resin into the sacrificial template made from the carbamide granules. Polyvinylpyrrolidone (PVP) solution in ethanol was used as the template binder. When the resin setting and the template extraction had been performed, the resultant porous material was pyrolysed in the nitrogen flow. Depending on PVP concentration in the template binder, final vitreous carbons had the following properties: bulk density at 0.17-0.22 g/cm3; porosity at 85.7%-89.0%; window size at 447-735 µm; Darcian permeability coefficient at (0.64-9.5)×10-9m2; non-Darcian permeability coefficient at (0.53-3.36)×10-4 m. High specific strength of above 8×103 Pa/(kg·m-3) was attained.

Study on Cold-Drawing in Powder-in-Tube Process in Fabricating Silver-Sheathed (Bi,Pb)-Sr-Ca-Cu-O Tapes

Since Cu oxide superconductors have been discovered, the application for this type of superconductor especially in the form of superconducting tape to be used as electric cable to transport the electricity. The aim to this study is to analyse the manufacture of superconducting wire with superconducting pellets as its precursor. A pellet disc of High Temperature Superconducting (HTS) Bi,Pb-Sr-Ca-Cu-O has been made by using solid state method. This pellet has been prepared by mixing each of oxide powders together, and then sintered at 865°C for 90 hours. We have analysed the samples using X-Ray Diffractometer (XRD), Energy Dispersive x-ray Spectroscopy (EDS), Scanning Electron Microscopy (SEM) and also resistivity measurement to confirm its superconductivity. After confirmed the superconducting properties of the pellet, it was grinded into powder and inserted into silver tube with outer diameter of 10 mm and thickness of 1 mm. And then, drawn to make monofilament wire. It were then cut and inserted into another silver tube, and then re-drawing and rolled into multifilament tapes using Powder-in-Tube (PIT) method. The multifilament tapes was heated at 850°C for 12 hours. We confirmed its phase crystalline and superconductivity at pellet disc. However, when the pellet disc was made into wire and sintered at 850°C, it became amorphous and conductivity behaviour was decline. According to SEM analysis and resistivity measurement result, silver also penetrated inside the sample region of multifilament wire.

Manufacture of Bi, Pb-Sr-Ca-Cu-O pellet disc using wet method

A confirmation of favorable properties of pellet disc of HTSBPSCCO is required in order to optimally do subsequent process of powder-in-tube (PIT) fabricated intosuperconductor wires. Wet method is a simple method in fabricating superconductor wire when it comes to mass production. In order to optimize this method, temperature parameter holds a decisive role in the formation of the 2223 phase of BPSCCO. We have synthesized two samples using wet method with the sintering temperature of 855°C and 865°C for 90 hours in air atmosphere.XRD analysis points out the formation of Bi-2223 phase of the sample with the sintering temperature of 855°C, whereas Bi-2212 phase is detected in the one with the sintering temperature of 865°C. The surface morphology of both samples are layers-like. According to temperature dependence of resistivity measurement results, both samples have superconductivity behavior below critical temperature (Tc). The former one (Tsintering = 855°C) has conductive-like behavior above Tcof which...

Effect of humid atmosphere on resistivity and crystallinity behavior of BPSCCO superconductor made by solid state method

High Tc superconductors (HTS) with the CuO2-based formula (Bi2-Sr2-Cam−1-Cum-Oy) are strongly hygroscopic material because their various phases in the CuO2-based material (Bi2-Sr2-Cam-1-Cum-Oy) are highly susceptible to attact moisture or water. In order to protect the HTS Bi,Pb-Sr-Ca-Cu-O (BPSCCO) from deterioration during fabrication process, controlled humid environment is prerequisite in formation of a stable and homogenous of 2223 phase of HTS BPSCCO. Samples have been synthesized using the solid state method with the sintering temperature of 865°C for 90 hours in air. The formation of Bi-2223 phase has been detected by XRD analysis on the samples before and after been exposed to water vapour at 40°C for 3 days. However, excessive phase of lead oxide is detected in the one before exposure to water vapour. According to temperature dependence of resistivity measurement results, samples beforeexposure to water vapour have superconductivity behavior belowcritical temperature (Tc final =100K) and conducti...