• Journal of Powder Materials
• /
• v.11 no.3
• /
• pp.224-232
• /
• 2004

Ni-diamond composite powders with nickel layer of round-top type on the surface of synthetic diamond (140/170 mesh) were prepared by the electroless plating method (EN) with semi-batch reactor. The effects of nickel concentration, feeding rates of reductant, temperature, reaction time and stirring speeds on the weight percentage and morphology of deposited Ni, mean particle size and specific surface area of the composite powders were investigated by Atomic Adsortion Spectrometer, SEM-EDX, PSA and BET. It was found that nucleated Ni-P islands, acted as catalytic sites for further deposition and grown into these relatively thick layers with nodule-type on the surface of diamond by a lateral growth mechanism. The weight percentage of Ni in the composite powder increased with reaction time, feeding rate of reductant and temperature, but decreased with stirring speed. The weight percentage of Ni in Ni-diamond composite powder was 55% at 150 min., 200 rpm and 7$0^{\circ}C$ .

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.57 no.4
• /
• pp.451-456
• /
• 2008

In this paper. we experimented and analyzed about evaporation and breaking process of filament by external flames and adsorption pattern in lamp bulb of evaporated filament particle according to the set-up directions of incandescent lamps. In the results of experiments, we could know that filament evaporation behavior of incandescent lamp that is established by down direction happened most vigorously and is difference in adsorption pattern of filament particle that is vaporized according to set-up directions. Also, glass bulbs were melted and filaments were evaporated by external flames, and finally molten marks were discriminated. We expect that become important data that this study finding reveals burnout cause of incandescent lamp in scene of a fire.

• Proceedings of the KIEE Conference
• /
• 2002.11a
• /
• pp.248-250
• /
• 2002

본 논문은 당뇨병의 지표물질인 glucose의 농도를 극미량의 시료를 사용하여 정량 할 수 있는 방법을 개발하기 위하여 효소 고정화 전극을 제작하였다. 전극은 실리콘 웨이퍼상에 마이크로 크기의 전극을 반도체 공정을 이용하여 제작하였고, 전기 화학적 방법으로 마이크로 전극에 전도성 고분자 Polypyrrole(PPy) 및 glucose oxidase(GOx)를 고정화한 고감도의 전기화학 전극을 개발하였다. 도전성 고분자의 전기 화학적 중합은 순환 전압 전류법으로 하였으며, 용액의 액성에 따른 효소의 표면 전하를 이용하여, 도전성 고분자를 코팅한 전극에 일정한 전압을 인가하고 GOx를 도우핑 하였다. 제작된 전극은 시간대 전류법으로 glucose의 농도에 따른 감도 측정결과 마이크로 리터의 시료에 $5{\mu}A$/decade를 얻었다. 전극의 표면분석은 Scanning electron microscopy(SEM), Energy dispersive X-ray spectroscopy(EDX)를 이용하였다.

• Tribology and Lubricants
• /
• v.25 no.1
• /
• pp.66-72
• /
• 2009

Al-based composites reinforced with SiC particulate were fabricated using a thermal spray process, and dry sliding wear behavior of the composites was investigated. Pre-mixed Al and SiC powders were sprayed on an A16061 substrate by flame spraying, and dry sliding wear test were performed under various sliding speed and applied load conditions against ${Al_2}{O_3}$ ball. Wear behavior of the composites was studied by using scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). And build-up mechanism of MML on the worn surface of the composites was examined. It was revealed that these MML was formed of debris from the contact surface of the composites and effected to wear behavior of the composites protecting the contact surface of the composites.

• Korean Journal of Materials Research
• /
• v.4 no.7
• /
• pp.741-749
• /
• 1994

The planar solid oxide fuel cell(SOFC) contains several ceramic materials depending on its structure and has rdfractory metal parts for manifolds, shrouds and current leads. Among ceramic materials for planar SOFC, joining of lanthanum chromite separator and yttria stabilized zirconia(YSZ) electoyte in planar SOFC stack to give strong gas tight seals is necessary for satisfactory operation and high performance. Nevertheless, for planar SOFC/sub s/, how to seal the cell stack and gas manifold remains as one of the unsolved problems. Therefore, in this study. we investigated the joining of sintered lanthanum chromite and YSZ pellets using unsintered lanthanum chromite green films as sealent. Scanning electron microscopy(SEM) and energy dispersive X-ray analysis(EDX) revealed that Ca in the sealing material diffused and dissolved into YSZ and sintered lanthanum chromite, and unsintered lanthanum chromite green films reacted with YSZ to from a new phase at the interface. Also, the densification of unsintered lanthanum chromite green films was inpeded by the Ca migration.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
• /
• 1999.05a
• /
• pp.165-170
• /
• 1999

Palladium membranes have high selectivity of separation and removal of hydrogen to chemical process at high temperature. For the development of hydrogen permeable membrane, palladium was deposited on porous stainless steel support by electroless plating method. In this work, the activation effect on the surface of stainless steel support has been investigated for the effective palladium plating. The morphology and microstructure were characterized by SEM and the composition was analyzed by EDX. It is found that the composition of deposited nuclei on the stainless steel support was changed in accordance with activation cycles. It is also observed that Sn-enriched nuclei has been changed to Pd-enriched nuclei over the fifteenth activation. The uniform deposition of the dense palladium layer on porous stainless steel support has been performing with Sn-enriched nuclei and comparing with Pd-enriched nuclei.

• Journal of Industrial and Engineering Chemistry
• /
• v.67
• /
• pp.187-198
• /
• 2018

Clay based coating with zwitterionic functionality is used to remove cationic and anionic dyes. Adsorbent coating was prepared by the mixing of bentonite clay, acrylic polymer (AP) and polyethylene-diamine (EPI-DMA). Characterization was performed using SEM-EDX, XRF, X-ray mapping and FTIR analyses. The adsorption capacity of ZACC was found to be increased from 59.35 to 255.99 mg/g and from 45.84 to 70.09 mg/g for BG and AR1 dyes, respectively using initial concentration (50-200 ppm). Significant adsorption capacity along with mechanical and chemical stability formulates ZACC as an excellent composite coating for treatment of anionic and cationic dyes from industrial wastewater.

• Journal of Radiation Industry
• /
• v.7 no.2_3
• /
• pp.141-147
• /
• 2013

The simple and facile radiation technique of the preparation of antibacterial biodegradable polymer films containing silver nanoparticles (Ag NPs) was described. The biodegradable poly(butylene adipate-co-terephthalate) (PBAT) films containing silver trifluoroacetate (Ag TFA) were prepared by a solvent casting method, and then the films were irradiated by electron beams at the various doses ranging from 20 to 200 kGy to form Ag NPs in the biodegradable polymers. The results of UV-vis and FE-SEM/EDX analyses revealed that the Ag NPs were successfully formed in the PBAT matrix during the electron beam irradiation, and their amounts were dependant on the absorbed dose and Ag TFA concentrations. Furthermore, on the basis of the results of the antibacterial test through disk diffusion and colony counting test, the irradiated PBAT/Ag TFA films exhibited the antibacterial property due to the formation of Ag NPs.

• Corrosion Science and Technology
• /
• v.20 no.5
• /
• pp.242-248
• /
• 2021

Unforeseen failures of boilers in power plants may affect the continuation of electricity generation. Main failures in boilers are influenced by the tube material, tube position, boiler service temperature and pressure, and chemical composition of the feed water and coal. This investigation was intended to find answers on the causes and mechanism of failure of the fire-side boiler water-wall tubes, due to perforation and corrosion. The tube conformed to the material requirements in terms of its chemical composition and hardness. Microscopic examination showed ferrite and pearlite indicating no changes in its microstructure due to the temperature variation. SEM test showed a single layer and homogenous film density particularly on the area far from perforation. However, layers of corrosion product were formed on the nearby perforation area. EDX showed that there were Na, Ca, S, and O elements on the failed surface. XRD indicated the presence of Fe₂O₃ oxide. The failure mechanism was identified as a result of significant localized wall thinning of the boiler water wall-tube due to oxidation.

• Korean Journal of Chemical Engineering
• /
• v.35 no.11
• /
• pp.2303-2312
• /
• 2018

Pretreatment process of silica-coated PET fabrics, a major low-grade PET waste, was developed using the reaction with NaOH solution. By destroying the structure of silica coating layer, impurities such as silica and pigment dyes could be removed. The removal of impurity was confirmed by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX). The pretreated PET fabric samples were used for depolymerization into its monomer, bis(2-hydroxylethyl) terephthalate (BHET), by glycolysis with ethylene glycol (EG), and zinc acetate (ZnAc) catalyst. The quality of BHET was confirmed by DSC, TGA, HPLC and NMR analyses. The highest BHET yield of 89.23% was obtained from pretreated PET fabrics, while glycolysis with raw PET fabric yielded 85.43%. The BHET yield from untreated silica-coated PET fabrics was 60.39%. The pretreatment process enhances the monomer yield by the removal of impurity and also improves the quality of the monomer.