• Journal of the Korean Electrochemical Society
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• v.18 no.2
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• pp.68-74
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• 2015

To compare the microstructure and electrochemical properties between two binary alloys (Cr-Si, Ni-Si), two composition of binary alloys with the same capacity were selected using phase-diagram and prepared by matrix-stabilization method to suppress the volume expansion of Si by inactive-matrix. Master alloys were made by Arc-melting followed by fine structured ribbon sample preparation by Rapid Solidification Process (RSP, Melt-spinning method) under the same conditions. Also powder samples were produced by wet grinding for X-Ray Diffraction (XRD) and electrochemical measurements. As predicted from the phase diagram, only active-Si and inactive-matrix ($CrSi_2$, $NiSi_2$) were detected. The results of Scanning Electron Microscope (SEM) and Transmission Electron Microscopy - Energy Dispersive X-ray Spectroscopy (TEM-EDS) show that Cr-Si alloy has finer microstructure than Ni-Si alloy, which was also predictable through phase diagram. The electrochemical properties related to microstructure were evaluated by coin type full- and half-cells. Separately, self-designed test-cells were used to measure the volume expansion of Si during reaction. Volume expansion of Cr-Si alloy electrode with finer microstructure was suppressed significantly and improved in cycle capability, in comparison Ni-Si alloy with coarse microstructure. From these, we could infer the correlation of microstructure, volume expansion and electrochemical degradation and these properties might be predicted by phase diagram.

• Journal of Korea Foundry Society
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• v.20 no.2
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• pp.116-121
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• 2000

Interfacial reaction and mechanical properties between Sn-Zn-X ternary alloys(X : 3wt.%In, 4wt.%Bi) and Cu-substrate were studied. Cu/solder joints were subjected to aging treatments for up to 50days to see interfacial reaction at $100^{\circ}C$ and then were examined changes of microstructure and interfacial compound by optical microscopy, SEM and EDS. Cu/solder joints were aged to 30days and then loaded to failure at cross head speed of 0.3 mm $min^{-1}$ to measure tensile strength. According to the results of the solderability test, additions of In and Bi in the Sn-9wt.%Zn solder improve the wetting characteristics of the alloy and lower the melting temperature. Through the EDS and XRD analysis of Cu/Sn-9wt.%Zn solder joint, it was concluded that the intermetallic compound was the ${\gamma}-Cu_5Zn_8$ phase. Cu-Zn intermetallics at Cu/solder interfaces played an important role in both the microstructure evolution and failure of solder joints. Cu/solder joint strength was decreased by aging treatment, and those phenomenon was closely related to the thickening of intermetallic layer at Cu/solder joints.

• Journal of Conservation Science
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• v.29 no.4
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• pp.355-366
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• 2013

Diverse scientific analyses, including microstructure, ICP-AES, SEM-EDS, and P-XRF(Bench Top type and Gun type), were carried out on 6 bronze artefacts which handed from generation to generation. Also, we attempted to study applicability for authenticity of the bronze artefacts using scientific analyses based on the specific element. The results of ICP-AES analysis showed that the bronze were formed from an alloy of Cu, Sn, Pb with trace elements such as Ag, As, Co, Fe, but there were not Zn found. The result of P-XRF are 10~25% lower in Cu and 10~20% higher in Sn than that of ICP-AES. This is because of destannification that the compound of $SnO_2$ are present on the surface. The results of SEM-EDS represented that there is lead segregation. It was difficult to study applicability for authenticity of bronze artefact according to the microstructures and chemical components of the bronze artefacts. Therefore, as bronze artefacts have shown different corrosion materials depending on the buried environment and conserving environment, identifying the authenticity would be possible on the basis of the additional researches on the corrosion and comparative research of ancient art.

• Applied Chemistry for Engineering
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• v.16 no.1
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• pp.150-152
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• 2005

$La_{0.2}Ca_{0.8}MnO_3$ colossal magnetoresistance (CMR) powders and pellets were synthesized by sol-gel process involving a stable metal chelate complex with acetylacetone. The structural changes of reaction mixture were monitored by FT-IR spectroscopy and X-ray diffractometry. The microstructure of sintered samples and the cation composition of gel powder were studied by FE-SEM/EDS and ICP-AES. The magnetic property was investigated as a function of temperature.

• Proceedings of the KWS Conference
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• 2006.05a
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• pp.218-220
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• 2006

Sn-3.0Ag-0.5Cu solder is widely used as micro-joining materials of flip chip package(FCP) because of the fact that it causes less dissolution and has good thermal fatigue property. However, compared with ternary electroplating in the manufacturing process, binary electroplating is still used in industrial field because of easy to make plating solution and composition control. The objective of this research is to fabricate Sn-3.0Ag-0.5Cu solder bumping having accurate composition. The ternary Sn-3.0Ag-0.5Cu solder bumping could be made on a Cu pad by sequent binary electroplating of Sn-Cu and Sn-Ag. Composition of the solder was estimated by EDS and ICP-OES. The thickness of the bump was measured using SEM and the microstructure of intermetallic-compounds(IMCs) was observed by SEM and EDS. From the results, contents of Ag and CU found to be at $2.7{\pm}0.3wt%\;and\;0.4{\pm}0.1wt%$, respectively.

• Applied Science and Convergence Technology
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• v.26 no.5
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• pp.143-147
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• 2017

Structural studies on the addition characteristics of Nb ions to $BaTiO_3$ solid solutions were performed by XRD and SEM/EDS technique. The X-ray diffraction peaks of the (111), (200) and (002) planes of Nb-doped $BaTiO_3$ solid solutions with different mole% of Nb were analyzed. We also investigated the relationship between the dielectric and structural properties of Nb-doped $BaTiO_3$. The transition temperatures of $BaTiO_3$ solid solution doped with 0.5mole%Nb and 1.0 mole%Nb were ${\sim}116^{\circ}C$ and ${\sim}87^{\circ}C$, respectively, which were found to be shifted to very low temperature from the transition temperature of pure $BaTiO_3$ (about $125^{\circ}C$). As a result of analysis of 1/K versus T and ln[$(1/K)-(1/K_m)$ versus ($T-T_m$)] of the two compositions used in this experiment, the diffusivity slightly differs from that of pure $BaTiO_3$ at temperatures above Curie temperature. And this characteristic was analyzed by applying the modified Curie-Weiss law.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.05a
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• pp.112-112
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• 2015

The purposed of this work was to determine nanotube shape variation on the Ti-xNb alloys with alloying elements and applied potentials. Samples were prepared by arc melting, followed by followed by homogenization for 12 hr at $1000^{\circ}C$ in argon atmosphere. This study was evaluated the phase and microstructure of Ti-xNb alloys using an X-ray diffraction (XRD) and optical microscopy (OM). The morphology of the samples was investigated with a field-emission scanning electron microscope (FE-SEM) and energy dispersive X-ray spectroscopy (EDS). The nanotube on the alloy surface was formed in 1 M $H_3PO_4$ with small additions of NaF 0.8 wt.%. All anodization treatments were carried out using a scanning potentiostat (Model 362, EG&G, USA) at constant voltage 30 V for 120 min, respectively. The morphology of the samples was investigated with a field-emission scanning electron microscope (FE-SEM) and energy dispersive X-ray spectroscopy (EDS). Surface characteristics of nanotbue formed on Ti-xNb alloys was investigated by potentiodynamic test and potentiostatic in 0.9% NaCl solution at $36.5{\pm}1^{\circ}C$. It was observed that the changed ${\alpha}$ phase to ${\beta}$ phase with Nb content.

• Journal of the Korean Institute of Gas
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• v.24 no.5
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• pp.39-46
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• 2020

This paper is considered about centerline segregation of API 5L steel used in pipeline. Mn/S, Nb and C were known as segregated elements in the centerline of pipe thickness. The Mn usually was accompanied by S consisting of long viscous shape. Microstructure of the centerline was composed of MnS and Nb/Ti indusions including oxide. The segregation effect in centerline region was analyzed by OM, SEM/EDS and micro Vickers hardness. The Mn, Nb and C are retarded elements in transformation from austenite to ferrite or martensite. These elements could derive a bainitic microstructure as a kind of martensite, which is different from difference and element segregation between in matrix and centerline derived from steel melting and heat treatment.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.27 no.5
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• pp.263-267
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• 2017

The Co-Cr as-cast alloys are widely used in the manufacturing of orthopedic implants made with investment casting techniques because of its high strength, good corrosion resistance and excellent biocompatibility properties. Carbide precipitation at grain boundaries and interdendritic regions is the major strenthening mechanism in the as-cast condition. In this study, effects of GPS (Gas Pressured Sintering) heat-treatment on the microstructure and crystallinity of the as-cast Co-Cr alloy prepared by investment casting were investigated. It was confirmed that the content of metal carbide ($Cr_{23}C_6$) was increased in the grain boundary by using optical microscopy (OM), field-emission scanning electron microscopy (FE-SEM) and energy dispersive spectroscopy (EDS).

• Composites Research
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• v.20 no.5
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• pp.43-48
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• 2007

The absorption and the interference shielding of electromagnetic wave have been very important issues for commercial and military purposes. The stealth technique is one of the most typical applications of electromagnetic wave absorption technology. This study has started for the development of composite fillers containing dielectric and magnetic lossy materials. To improve the electromagnetic characteristics of conductive nano fillers, carbon nanofibers (CNFs) with nickel-phosphorous (Ni-P) or nickel-iron (Ni-Fe) have been fabricated by the electroless plating process. Observations by the electron microscopy (SEM/TEM) and element analyzer (EDS/ELLS) showed the uniform Ni-P and Ni-Fe coated CNFs. The compositions of the plating layers were about Ni-6wt%P and Ni-70wt%Fe, respectively. The average thicknesses of the plating layers were about $50\;{\sim}\;100\;nm$.