Papers by Keyword: Bi

Abstract: Bi-type superconductor is a high-temperature superconductor with mainly applied in the field of electricity. Silver is used as a wire sheath which causes the price of this wire production to be high. In this study Bi(Pb)-Sr-Ca-Cu-O (BPSCCO) wires were made by using stainless-steel (SS316) tubes which is cheaper and is not change its properties by the temperature of the formation of BPSCCO at 860°C. The preparation of superconducting wire is done by the Powder-In-Tube method, sintering and withdrawing/ rolling process. TiO₂ powder was added to analyze the effect on the formation of BPSCCO. Based on analyzing results, there is a dominant impurity phase that has been formed, namely Fe_2.5Ti_0.5O₄. We found that in the use of stainless-steel tubes and the TiO₂ powder (5wt%), 2223 phase was not formed. Although, small amounts of Bi₂Sr₂CaCu₂O₈ (2212) and Bi₁₀Sr₁₀Cu₅O₂₉ (2201) phases were found. Resistance versus temperature test using cryogenic equipment results indicate that there are symptoms of a low critical temperature around 10 K. 2212 and 2201 phases are thought to cause a low critical temperature in the samples, even though the decrease in electrical resistance does not reach zero. While the morphology of superconducting wire is quite well characterized from fairly even grains and only a small amount of porosity is formed.

Abstract: In the present paper, based on Bi-containing hypereutectic Al-20%Si alloy, a rotating magnetic field was used, the microstructures of the alloy have been observed and analyzed by optical microscope and scanning electronic microscope, and its wear-resisting property was measured. The influence mechanism of rotating magnetic field on the microstructures and properties of the alloy has been discussed. Research results show that exerting a rotating magnetic field in the hypereutectic Al-20%Si alloy drastically decreases the amount of primary Si phase, only some tiny bulk Si exist and the amount of needle eutectic Si increase. The dendrite-like primary α-Al appears at the same time. With the increase of stirring rate of rotating magnetic field, the change way of eutectic Si shape is coarse needle→tiny needle→coarse needle; the rotating magnetic field can change the nonuniform distribution of Bi induced by Bi local decentralization. With the increase of stirring rate of rotating magnetic field, the change way of Bi shape in upper part microstructures of the alloy is large bulk→short rodlike→big globular→small globular, Bi local decentralization is changed into uniform distribution; In addition, exerting a rotating magnetic field in the hypereutectic Al-20%Si alloy can increase wear-resisting property of the alloy.

Abstract: The research on a new low-Ag lead-free solder has become a hot spot in the field of electronic packaging. In this work, the effects of Bi addition on microstructure, melting temperature, wettability of low-Ag solder, shear strength of solder joint and the growth of interfacial intermetallic compound (IMC) before and after thermal cycling were investigated. A moderate amount of Bi element resulted in the microstructural refinement and melting temperature reduction of Sn-0.2Ag-0.7Cu solder. Wetting test results showed that a small amount of Bi produced the significant effect on improving the wettability. In addition, it is shown that the thickness of interfacial IMC during thermal cycling decreased first and then increased; the shear strength of solder joint increased with the increase of Bi.

Abstract: In this paper, it extracted and monitored the ground temperature, urban land, green space, water, bare ground in Xi'an used LANDSAT images in different periods of 1995, 2006 and 2013, analyzed the relationship between the changes of urban underlying surface and heat island in the past 20 years in Xi'an city, which is in order to provide basic information for urban rational designation and improve environmental conditions. The study found: it was feasible and accurate to study of the relationship between urban heat island and urbanization expansion based on index method, which had more statistically significant compared to the traditional classification methods and achieved a shift from qualitative to quantitative. The results show that: the urban heat island and Xi'an urbanization expansion is significantly correlated. The urban heat island is negatively correlated with green space and water body, and is positively correlated with buildings and bare land; in the past 20 years, Xi'an city expanded approximately 4.25 times, the heat island area continued to grow, but the strength enhanced first and then weakened; since 2006, the green space and water area have grown within the third ring road, the urban structure has become more rational, the trend of urban heat island has slowed. Keyword:UHI;Urban expansion;NDBI;NDVI;MNDWI;BI

Abstract: The aim of this work is to report on the preparation of bismuth and gold nanoparticles ablating the corresponding target immersed in different liquid solutions: water and ethanol. The effect of the liquid environment and laser fluence used for ablation on the size and size distribution of the nanoparticles synthesized was investigated. The nanoparticle size was measured by transmission electron microscopy (TEM). In general terms, for both metals, the results obtained reveal smaller sizes as low as approximately 2 nm. The bismuth nanoparticles, as deposited, are highly crystalline in nature and, depending on the conditions of preparation, either Bi or Bi₂O₃ nanoparticles are obtained in both liquids. UV-Vis measurements show the typical band absorption characteristic of spherical particles of nanometric size. It is worth mentioning that the gold colloids obtained using water are very stable.

Abstract: The paper researched the method of using the L-Cysteine to pre-reduction and using hydrid atomic fluorescence spectrometry to determining the As、 Sb 、Bi and Hg elements.In the preparation determination condition,the elements have a wide linear rangeand, the sample analysis results coincided with the recommended values. Detection limit of each element wereAs0.08ng／mL、Sb 0.06ng／mL、Bi 0.07ng／mL、Hg 0.004ng／mL。After nearly more than 100,000 pieces of the determination of geochemical samples, the sample have a good parallel.

Abstract: Related theories about business intelligence and supply chain management (SCM) are introduced firstly, then the critical technologies about business intelligence-based supply chain management (BISCM) are discussed, and at the same time, the integrated framework of BISCM is proposed. It is believed that the integration of SCM with BI can resolve the problem of “rich data but poor information”, and enhance the competitive advantage for enterprises involved in the SCM so as to beat all other competitors in the fierce competition.

Abstract: Five Al-Bi-Sn-In-Ga alloys with different Bi content were designed and prepared. Their electrochemical properties in 3% sodium chloride solution, the distribution of alloying elements and surface morphologies were studied by means of loss of weight method, polarization curve, electrochemical impedance spectroscopy (EIS) and energy spectrum analysis. The results indicate that, a good deal Bi and other alloying elements form new phases which exist in grain boundaries in the form of dot or granule, and Bi rich regions are prone to become the inductive points of pitting corrosion. Moreover, there is a certain linear relation between Bi content and the self corrosion rate.

Abstract: Thermal stability of  grains and tensile ductilities at room and elevated temperatures were investigated and compared for Mg-3%Zn-0.4%Zr and Mg-3%Zn-0.4%Zr-1%Bi alloys in hot-rolled state. The Bi-added alloy showed slightly finer-grained microstructure with enhanced thermal stability, which is closely associated with fine Mg-Bi compounds acting as obstacles for the migration of grain boundaries. The Mg-3%Zn-0.4%Zr-1%Bi alloy exhibited better tensile strength at room temperature and tensile ductilities at elevated temperature. Finer and more homogeneous grain structure with higher thermal stability would be responsible for the enhanced tensile properties in the Bi-added alloy.

Abstract: Defects distribution in 6H-SiC implanted with Bi ions was investigated with the local cathodoluminescence. There are two typical areas with radiation defects found in implanted samples. Implanted layer was about 27 micrometers depth. Far-action area with radiation defects was observed for the first time. Thickness of this area varies from few tens up to hundreds micrometers. This effect depended on concentration of defects i.e. irradiation fluence. Radiation defects at this area disappeared after annealing the sample if fluence is not to high.