• Progress in Superconductivity
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• v.13 no.2
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• pp.127-132
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• 2011

Many research groups have been manufacturing coated conductor by various processes such as PLD, MOD, and MOCVD, but the methods with production cost suitable for wide and massive application of coated conductor did not develop yet. Spray pyrolysis method adopting ultrasonic atomization was tried as one of the possible option. GdBCO precursor films have been deposited on IBAD substrate by spray pyrolysis method at low temperature and converted to GdBCO by post heat treatment. Ultrasonic atomization was used to generate fine droplets from precursor solution of Gd, Ba, and Cu nitrate dissolved in water. Primary GdBCO films were deposited at $500^{\circ}C$ and oxygen partial pressure of 1 torr. After that, the films were converted at various temperatures and low oxygen partial pressures. C-Axis oriented films were obtained IBAD substrates at conversion temperature of around $870^{\circ}C$ and oxygen partial pressures of 500 mtorr ~ 1 torr in a vacuum. Thick c-axis epitaxial film with the thickness of 0.4 ~ 0.5 ${\mu}m$ was obtained on IBAD substrate. C-axis epitaxial GdBCO films were successfully prepared by ex-situ methods using nitrate precursors on IBAD metal substrate. Converted GdBCO films have very dense microstructures with good grain connectivity. EDS composition analysis of the film showed a number of Cu-rich phase in surface. The precursor solution having high copper concent with the composition of Gd : Ba : Cu = 1 : 2 : 4 showed the better grain connectivity and electrical conductivity.

• Journal of Conservation Science
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• v.36 no.3
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• pp.213-224
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• 2020

This research conducted a component analysis and conservation treatment of "Sangryangmun," a material which had been written in 1965 and was discovered during the repair project for "Jinnamgwan" in Yeosu. The "Sangryangmun" has been stored in a cylindrical metal storage; however, defects, discolorations, hardening, and damages caused by pollutants were found. Based on the XRF analysis, rust in the cylindrical metal storage, which was made of Cu, was stuck on the surface of the "Sangryangmun". Using FT-IR and Pyrolysis-GC/MS analyses, carbonyl and compounds of fatty acids were detected; the organic material on the surface of the "Sangryangmun" was identified to have belonged to oil-based components. Therefore, it was presumed that the bast fibers of a mulberry was used in the paper. To determine the conservation materials, component analysis, condition survey, and preliminary test on adhesives were conducted. Moreover, the missing parts and partial linings were filled using mulberry-fiber paper, methyl cellulose, etc.

• Journal of the Microelectronics and Packaging Society
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• v.23 no.3
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• pp.69-75
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• 2016

This study investigated the effect of heat treatment conditions not only on the Cr surface crack propagation behaviors but also on the Ni/Cr interfacial reaction characteristics in electroless Ni/electroplated Cr double coating layers on Cu substrate. Clear band layer of Ni-Cr solid solutions were developed at Ni/Cr interface after heat treatment at $750^{\circ}C$ for 6 h. Channeling cracks formed in Cr layer after 1 step heat treatment, that is, heat treatment after Ni/Cr plating, while little channeling cracks formed after 2 step heat treatment, that is, same heat treatments after Ni and Cr plating, respectively, due to residual stress relaxation due to crystallization of Ni layer before Cr plating.

• Bulletin of the Korean Chemical Society
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• v.23 no.1
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• pp.112-118
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• 2002

Good-to-excellent yields of 2,3-Disubstituted norbornenes (or norbornanes) were obtained using a Pd/Cu catalyzed three-component ternary coupling reaction of aryl halides, norbornadiene (or norbornene), and alkynols in toluene at $100{\circ}C$ in the presence of 5.5 M NaOH as a base and benzyltriethylammonium chloride as a phase transfer catalyst. The results of experiments using various aromatic halides suggest that the ternary coupling reaction is promoted by bromide.

• Korean Journal of Materials Research
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• v.11 no.11
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• pp.923-928
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• 2001

An electrolytic silver plating process has been successfully developed for terminated electrode parts of dielectric ceramic resonator. High adhesion strength and high Qu is obtained and blister occurance is minimized under plating condition with $HNO_3$750 $m\ell/\ell$ and HF $ 250m\ell/\ell$ solution at $25^{\circ}C$ for 20 minutes. Adhesion strength has the highest value, 3.2 kg/mm$^2$ at etching temperature of $25^{\circ}C$. Adhesion strength, Qu and blister occurance are monotonically increased with the thickness of electrodeposition layer. In case of electrodeposition of Ag, Qu value of 380 has obtained higher than in case of electrolytic Cu plating with Qu value of 325. Therefore, terminated electrode parts of dielectric ceramic resonator reducing dielectric loss can be obtained using prensent process.

• Journal of Magnetics
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• v.6 no.4
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• pp.145-147
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• 2001

The effect of interface roughness between [Ni/Mn] superlattice and pinned NiFe layer on magnetoresistance (MR) of [Ni/Mn] superlattice-based spin valve films was investigated. Antiferromagnetic phase structure and interface roughness of [Ni/Mn] superlattice spin valve films were compared in the as-deposited and the annealed samples at 240$\^{C}$, respectively. Surface morphology of spin valves was substantially flattened due to the formation of the antiferromatic NiMn phase. In case of Co insertion between Cu and NiFe, the interlace roughness and MR ratio in the annealed [NiMn] superlattice and pinned NiFe/Co layer increased more than those in the annealed [Ni/Mn] superlattice and pinned NiFe layers respectively.

• 보존과학연구
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• s.23
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• pp.149-162
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• 2002

Gilt bronze locks(Treasure No. 1141) excavated from Hancheonsa temple are artifacts of Goryeo Dynasty. The locks underwent a conservation process from October 2001 to July 2002. The process included cleaning and the application of corrosion inhibitors, Benzotriazolesolution, as well as reinforcement treatment with Paraloid NAD-10 solution,an acrylic resin. Non-destructive XRF analysis unveil that the artifacts are made of an alloy of copper(Cu), tin(Sn) and lead(Pb), but the gilt layer is too thin to analyze the purity of the gold or the exact production method. Gilt bronze locks are important materials because they preserve all the structures of locks in Goryeo Dynasty to the smallest detail. The surface pattern is revealed through the conservation process and components of the alloy through material analysis.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.283-283
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• 2013

Because of beautiful glossy and color, the value of gold leverage is very high in Europe. To improve the quality of gold alloys, we performed heat treatment on 14 K white gold alloys by variously changing age-hardening conditions. Age-hardening behavior and the related phase transformation changes were studied to elucidate the hardening mechanism of 14 K white gold alloy. For solid solution treatment [ST], casted gold alloy specimens were treated at high temperature ($750^{\circ}C$) for 30 minutes, and the specimens dropped to water to quench them. For Age-hardening treatment [AT], the specimens were treated at various temperatures ($250{\sim}300^{\circ}C$). After the heat treatment, we observed the phenomenon to increase hardness from 126 Hv to 166 Hv by Vicker's hardness tester. Through electron probe micro-analysis (EPMA) mapping analysis, we investigated that irregular particles were changed uniformly. In the SEM and OM images, two phases of matrix and particle-likestructures were observed, and the precipitation of these elements from the matrix progressed during age-hardening. By transmission electron microscope and X-ray diffraction observation, it was revealed that the formation of the Au3Cu superstructure contributed to the age-hardening at $270^{\circ}C$ in the gold alloy. After the heat treatment, this analysis shows that casted gold alloys were to improve hardness and to moderate surface defects at specific temperatures and duration.

• Journal of the Korean institute of surface engineering
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• v.48 no.1
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• pp.11-22
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• 2015

Pd alloy hydrogen membranes for hydrogen purification and separation need thermal stability at high temperature for commercial applications. Intermetallic diffusion between the Pd alloy film and the porous metal support gives rise to serious problems in long-term stability of Pd alloy membranes. Ceramic barriers are widely used to prevent the intermetallic diffusion from the porous metal support. However, these layers result in poor adhesion at the interface between film and barrier because of the fundamentally poor chemical affinity and a large thermal stress. In this study, we developed Pd alloy membranes having a dense microstructure and saturated composition on modified metal supports by advanced DC magnetron sputtering and heat treatment for enhanced thermal stability. Experimental results showed that Pd-Cu and Pd-Ag alloy membranes had considerably enhanced long-term stability owing to stable, dense alloy film microstructure and saturated composition, effective diffusion barrier, and good adhesive interface layer.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.153-153
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• 2017

The application of the coating supports the mechanical characteristics of the implant, and various materials and coatings are currently being used in the implant in a way to accelerate adhesion. Especially, plasma electrolytic oxidation (PEO) coating has been proposed continually with good surface treatment of titanium alloys. Also, the PEO process can incorporate Ca and P ions on the titanium surface through variables varied factor. PEO process for bioactive surface has carried out in electrolytes containing Ca and P ions. Natural bone is composed of mineral elements such as Mg, Si, Zn, Sr, and Mn, etc. Especially, Mg and Si of these elements play role in bone formation and growth after clinical implantation of bio-implants. In this study, corrosion charateristics of PEO-treated Ti-6Al-4V alloy in solution containing Si and Mg ions has been investigated using several experimental techniques. The PEO-treated surfaces were identified by X-ray diffraction, using a diffractometer (XRD, Philips X' pert PRO, Netherlands) with Cu $K{\alpha}$ radiation. The morphology was observed by field-emission scanning electron microscopy (FE-SEM, Hitachi 4800, Japan) and energy-dispersive X-ray spectroscopy (EDX, Oxford ISIS 310, England). The potentiodynamic polarization and AC impedance tests for electrochemical degradations were carried out in 0.9% NaCl solution at similar body temperature using a potentiostat with a scan rate of 1.67mV/s and potential range from -1500mV to + 2000mV.