• 한국재료학회지
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• 제24권1호
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• pp.60-65
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• 2014

Fe-based amorphous coatings were fabricated on a soda-lime glass substrate by the vacuum kinetic spray method. The effect of the gas flow rate, which determines particle velocity, on the deposition behavior of the particle and microstructure of the resultant films was investigated. The as-fabricated microstructure of the film was studied by field emission scanning electron microscopy (FE-SEM) and high resolution transmission electron microscopy (HR-TEM). Although the activation energy for transformation from the amorphous phase to crystalline phase was lowered by severe plastic deformation and particle fracturing under a high strain rate, the crystalline phases could not be found in the coating layer. Incompletely fractured and small fragments 100~300 nm in size, which are smaller than initial feedstock material, were found on the coating surface and inside of the coating. Also, some pores and voids occurred between particle-particle interfaces. In the case of brittle Fe-based amorphous alloy, particles fail in fragmentation fracture mode through initiation and propagation of the numerous small cracks rather than shear fracture mode under compressive stress. It could be deduced that amorphous alloy underwent particle fracturing in a vacuum kinetic spray process. Also, it is considered that surface energy caused by the formation of new surfaces and friction energy contributed to the bonding of fragments.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 춘계학술대회 논문집
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• pp.5-9
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• 2005

$LiFePO_4$ is a potential candidate for the cathode material of the lithium polymer batteries. $LiFePO_4$ cathode active materials were synthesized by coating on the $LiFePO_4$ was tried using $TiO_2$ and corbon in oreder to increase cyclic performance and electronic conductivity. Highly dispersed on the particles enhances the electronic conductivity and increases the capacity. For lithium polymer battery applications, $LiFePO_4$/SPE/Li and $LiFePO_4$-$TiO_2$/SPE/Li 'cells were characterized electrochemically by cyclic volatammetry and charge/discharge cycling. The $LiFePO_4$-carbon-$TiO_2$ cathode in PVDF-PC-EC-$LiCIO_4$ electrolyte showed high capacity at high current density.

• 자원리싸이클링
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• 제26권6호
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• pp.97-101
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• 2017

메탈폼은 매우 많은 기공을 포함하는 세포상 구조를 갖는 고체금속을 일컫는다. 특히 관통 기공 같은 개기공들은 고온용 필터 및 촉매 지지체 등으로 산업적으로 많이 사용되고 있다. 본 연구에서는 슬러리 코팅공정으로 90% 이상의 기공율과 2 mm 이상의 기공크기를 갖는 Fe 폼을 제조하였다. 이때 Fe 분말과 $Fe_2O_3$ 분말의 혼합비를 달리하여 기공율과 기공크기를 제어하였다. 이를 위해 우선 분말, 증류수 및 폴리비닐알콜(PVA)를 균일하게 혼합하여 슬러리를 제조하였다. $Fe_2O_3$ 분말의 혼합 비율이 증가할수록 PU 폼에 코팅된 슬러리의 양이 증가한 반면 Fe 폼의 수축 및 기공율은 각각 감소하였다.

• 한국결정성장학회:학술대회논문집
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• 한국결정성장학회 1997년도 Proceedings of the 13th KACG Technical Meeting `97 Industrial Crystallization Symposium(ICS)-Doosan Resort, Chunchon, October 30-31, 1997
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• pp.173-179
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• 1997

출발원료로 ferric nitrate, ethylene glycol, acethyl acetone 혼합용액을 사용하여 dip-coating된 $\alpha$-Fe$_2$O$_3$막을 제조하였다. coating을 위한 혼합용액의 시간의 경과에 따른 용액내의 가교(polymerization) 효과를 관찰하기 위해서 적외선 분광기(FT-IR)을 사용하였고, 막 형성 시 유기물 분해 및 결정화 시작 온도를 확인하기 위하여 FT-IR, XRD, DSC 등을 이용하여 분석을 행하였다. 또한 각 조건에서 제조된 막은 X-선 회절 분석을 통해 결정상을 확인 하였으며, SEM을 통하여 막의 두께 변화에 대하여 관찰하였다.

• Corrosion Science and Technology
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• 제22권2호
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• pp.90-98
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• 2023

In this study, cobalt oxide (Co₃O₄) and cobalt-doped magnetite (CoFe₂O₄) nanoparticles were synthesized by a hydrothermal method. They were then used as corrosion inhibitors for corrosion protection of AA2024-T3 aluminum alloys. These obtained nanoparticles were characterized by x-ray diffraction, field-emission scanning electron microscopy, and Zeta potential measurements. Corrosion inhibition activities of Co₃O₄ and CoFe₂O₄ nanoparticles were determined by performing electrochemical measurements for bare AA2024-T3 aluminum alloys in 0.05 M NaCl + 0.1 M Na₂SO₄ solution containing Co₃O₄ or CoFe₂O₄ nanoparticles. Corrosion protection for AA2024-T3 aluminum alloys by a water-based epoxy with or without the synthesized Co₃O₄ or CoFe₂O₄ nanoparticles was investigated by electrochemical impedance spectroscopy during immersion in 0.1 M NaCl solution. The corrosion protection of epoxy coating deposited on the AA2024-T3 surface was improved by incorporating Co₃O₄ or CoFe₂O₄ nanoparticles in the coating. The corrosion protection performance of the epoxy coating containing CoFe₂O₄ was higher than that of the epoxy coating containing Co₃O₄.

• 한국표면공학회지
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• 제51권1호
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• pp.34-39
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• 2018

Steel crucible used for molten Al has a problem of very limited lifetime because of the interaction between Fe and molten Al. This study was performed to improve the lifetime of steel crucible for molten Al by coating metallic Al and by further anodizing treatment to form thick and uniform anodic oxide films. The lifetime of the steel crucible was improved slightly by Al coating from 30 to 40 hours by metallic Al coating and largely to 120 hours by coating the surface with anodic oxide film. The improved lifetime was attributed to blocking of the reaction between Fe and molten Al with the help of anodic oxide layer with more than 20 um thickness on the crucible surface. The failure of the steel crucible arises from the formation of intermetallic compounds and pores at the steel/Al interface.

• 한국표면공학회지
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• 제47권1호
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• pp.13-19
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• 2014

The various surface treated conditions of Fe-3.0%Ni-0.7%Cr-1.4%Mn-X steel such as as-received, ion nitriding, DLC coated, DLC coated after nitriding for 3 hrs and 6 hrs were investigated to evaluate the beneficial effect for plastic mold steel. Micro Vickers hardness tester was used to estimate nitriding depth from the hardness profile and to measure hardness on the surface. Elastic modulus and residual stress were measured by a nanoindentator. Scratch test and SP (small ball punch test) were utilized to assess the adhesive strength of DLC coating. The depth of nitriding layer was measured as $50{\mu}m$ for the condition of 3 hrs nitriding and $90{\mu}m$ for that of 6 hrs nitriding. Hardness, elastic modulus, residual stress of DLC coating were 20.37 GPa, 162.78 GPa and -1456 MPa respectively. Residual stress on the surface of DLC coating after nitriding could increase to -3914 MPa by introducing nitriding before DLC coating. During the 'Ball-On-Disc' test ${\gamma}^{\prime}$ particles pulled out from the surface of nitrized layer tend to enhance abrasive wear mode since the fraction of ${\gamma}^{\prime}$ (Fe4N) in ion-nitrized layer is known to increases with nitriding time. Thus the specific wear rate of the nitriding layer increased. Comparing with nitriding the specific wear rate in work piece disc as well as ball decreased prominently in DLC coating due to the remarkable reduction in friction coefficient.

• 한국표면공학회지
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• 제42권2호
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• pp.86-94
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• 2009

Various types of multilayer coatings including Al/$Al_2O_3$ structure have been prepared on Nd-Fe-B permanent magnet to modify the morphology of the coating and to enhance the corrosion resistance of the magnet. Magnetron sputtering has been employed to make the multilayer coatings. $Al_2O_3$sputtering conditions were optimized in reactive sputtering by varying the deposition parameters. The formation of $Al_2O_3$ film was confirmed from the binding energy shift measured by electron spectroscopy for chemical analysis. 3 types of coating structures were designed and prepared by magnetron sputtering. The coating structures consist of (1) single Al coating, (2) modified coatings having oxide or plasma treated layer in the middle of coating structure, and (3) Al/$Al_2O_3$ multilayer coatings. Surface and cross-sectional morphologies showed that Al/$Al_2O_3$ multilayer grew as a layered structure, and that very compact Zone 3 like structure were formed. X-ray diffraction peak showed that the crystal orientations of multilayer coatings were similar to that of the bulk powder pattern. Hardness increased drastically when the Al thickness was around 1im in the Al/$Al_2O_3$ multilayer. From the salt spray test and pressure cooker test, it has been shown that the multilayer coatings showed good corrosion resistance compared to Al single or modified layer coatings.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1998년도 제28회 추계학술대회
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• pp.265-271
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• 1998

High temperature wear behavior of plasma sprayed zirconia based coating sealing with zirconia sol were investigated for high temperature wear resistance application. The zirconia powders containing 2.5, 5.0, 7.5, 10.0 mol% of MoS$_2$, $Fe_2O_3$ for plasma spray were made by spray drying method. As-sprayed coating was sealed by zirconia-sol to fill up the pore and crack in coating. wear test were performed at temperature ranges from room temperature to 600$\circ$C. The microstructural changes of before and after sealing process were examined by SEM, XRD and EPMA. After sealing process, the porosity was decreased and micro-hardness was increased. The wear properties of coating after sealing process were improved by sealing of pores and cracks. The behavior of wear amount and coefficient of friction were same tendency to before sealing process.

• 한국표면공학회지
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• 제32권1호
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• pp.31-42
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• 1999

The effect was investigated that aluminium in the zinc bath has on the coating adhesion of Hot-rolled Galvanized Iron(HGI) manufactured without pickling process. It is thought that the coating adhesion of HGI manufactured without pickling process is good due to the fact that increasing aluminium content in the zinc bath makes zinc and aluminium diffuse to the cracks or pores in the scale formed through the reduction heat treatment, and Fe-Zn-Al compound with good ductility is formed in the scale layer and plays a role of anchor between zinc coating and substrate. It is possible that HGI with the good coating adhesion was produced without pickling treatment in the zinc bath with more that 3wt% of Al content even at the $550^{\circ}C$ of conventional reduction heating temperature. In creasing the temperature of heating section and aluminium content in the zinc bath prevents the Zn-Fe alloy. The corrosion resistance of HGI manufactured without pickling process is excellent because of the mixed reaction of zinc sacrifice and aluminium passivity film.