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MgB2 has the potential for superconducting wire applications because it has a simple crystal structure, high current density and coherence length, and grain boundaries transparency. So, it is expected to be used as a substitute for Nb3Sn and NbTi superconducting materials in magnetic resonance imaging (MRI) applications in the health sector. The chemical doping technique to achieve the superconductivity phenomenon is considered the most effective in increasing the Jc and Hc of the MgB2 superconductor. The chemical doping technique in the form of nano carbon and graphite using the powder in sealed tube (PIST) method was carried out in this study by inserting Mg, B, and various carbon powders into a 316 stainless steel tube with the desired composition, then both ends of the tube were pressed to isolate the sample from oxidation during the sintering process. Four (4) variations of carbon doping composition in this study, i.e., variation carbon doping as much as 5 and 10 wt.%, then variation graphite as much as 5 and 10 wt.%. The effect of adding graphite and carbon nanoparticles is known through X-ray diffraction (XRD) analysis to determine the phase change and crystal structure, then observations using scanning electron microscope (SEM) to determine particle size, homogeneity, and porosity of each sample. The effect of adding of graphite and carbon nanoparticles is known through XRD analysis and observations using SEM. Analysis of the XRD results showed that the peaks formed were MgB2, and the other phases were Mg, B, C, and MgO, with an average crystal size of 38.1159, 33.5453, 28.0377, 17.0373, and 25.2136 nm. While the results of SEM observations indicate that the grains have started to become homogeneous, there is still porosity and agglomeration in some samples with an average grain size of 2.4913, 2.51926, 2.5163, 2.53742, and 2.5126 µm. [ABSTRACT FROM AUTHOR]

Superconductor is a material which when an electric current flows through it, it will not lose energy or can be said to have zero resistance at low temperatures. The manufacture of BaPb0.7Bi0.3O3 superconducting material by means of the solids method where the sample is processed through solid mixing then calcined and continued sintering at a temperature of 600, 610, 620, and 630°C for 12 hours. Then continued testing using X-ray diffraction, scanning electron microscope and superconductivity test using cryogenic. From the results of X-ray diffraction, the highest tetragonal structure was obtained at a sintering temperature of 610°C of 75.9% with a Tc value of 11.8 K. [ABSTRACT FROM AUTHOR]

The Abradable material coating has been widely applied to protect metal component from severe wear problem. This research is focused on coating ST-37 steel using abradable brake lining material by adding copper conductive material as heat conductor material using the HVOF coating method. Application of HVOF method for abradable material coating is rarely found, however it has potential for this application since the method can produce thick and dense coating layer. This research was conducted by varying the spraying distance of 20, 30, and 40 cm and variation of surface treatment to vary the surface roughness of substrate. Among characterization performed after the coating are wear test, microstructure, hardness, and SEM characterization. Based on the data obtained from the study, it was found that the abradable material layer resulting from the surface treatment of blasting etching with a spray distance of 20 cm has the most optimal value in terms of the least amount of porosity in coatings with ST-37 steel, the highest value of coating hardness of 468.2 HV0,5 kgf, the thickest average layer with an average value of 132.36 µm, and the lowest mass reduction of 0.00148 mg. For wear characteristics it is found that all layers with surface treatment and spraying distance have abrasive wear characterized by plowing or fragmentation. [ABSTRACT FROM AUTHOR]

Carbon Fiber Cementitious Composites (CFCC) is one of the most important materials in smart concrete applications. CFCC should be able to have the piezoresistivity properties where its resistivity changes when there is applied a stress/strain. It must also have the compressive strength qualification. One of the important additives in carbon fiber cementitious composites is dispersant. Dispersion of carbon fiber is one of the key problems in fabricating piezoresistive carbon fiber cementitious composites. In this research, the uses of dispersants are methylcellulose, mixture of defoamer and methylcellulose and superplasticizer based polycarboxylate. The preparation of composite samples is similar as in the mortar technique according to the ASTM C 109/109M standard. The additives material are PAN type carbon fibers, methylcellulose, defoamer and superplasticizer (as water reducer and dispersant). The experimental testing conducts the compressive strength and resistivity at various curing time, i.e. 3, 7 and 28 days. The results obtained that the highest compressive strength value in is for the mortar using superplasticizer based polycarboxylate dispersant. This also shown that the distribution of carbon fiber with superplasticizer is more effective, since not reacting with the cementitious material which was different from the methylcellulose that creates the cement hydration reaction. The research also found that the CFCC require the proper water cement ratio otherwise the compressive strength becomes lower. [ABSTRACT FROM AUTHOR]