• 한국세라믹학회:학술대회논문집
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• 한국세라믹학회 2003년도 춘계총회 및 연구발표회 초록집
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• pp.134.1-134
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• 2003

• 한국분말재료학회지
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• 제2권3호
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• pp.201-207
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• 1995

In general, the characteristics of plasma spray coating are strongly dependent on process conditions. In this paper, Mo and Co alloy coating layers were made by plasma spraying with different spray parameters and characterized using X-ray diffraction, scanning electron microscopy(SEM), hardnass test, and wear test. It was found that the coating characteristics were mainly affected by phase composition of the powder, spray distance, arc current, and gas flow rate.

• 한국주조공학회지
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• 제28권1호
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• pp.20-24
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• 2008

The characteristics, such as roughness, thickness, microhardness and corrosion resistance, of plasma electrolytic oxide coatings on AZ91D alloy were investigated under the processing condition of various coating times. The coatings on AZ91D alloy consisted of MgO, $MgAl_{2}O_{4}$ and $Mg_{2}SiO_{4}$ oxides. The surface roughness and thickness of coatings became larger with increasing the coating time. The microhardness in cross section of coatings was much higher than not only that in surface but that in the conventional anodic oxide coatings, which increased progressively as the coating time increased. After being immersed in 3.5%NaCl solution and methyl alcohol, the corrosion resistance of AZ91D alloy was markedly improved by plasma electrolytic oxidation coating treatment, and the AZ91D alloy coated for 50min revealed excellent corrosion resistance.

• 한국결정성장학회지
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• 제30권2호
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• pp.66-72
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• 2020

본 연구에서는 CaO-Al₂O₃-SiO₂(CAS) 계 유리 벌크와 유리 분체를 알루미나 소결체 표면에 스프레이 코팅막 적용 시 내플라즈마 특성에 대하여 비교하였다. CAS 유리 벌크와 유리 코팅막을 CF₄/O₂/Ar 플라즈마 가스에 노출시켰을 때의 식각율과 표면의 미세구조 분석을 통해 내플라즈마 특성을 확인하였다. CAS 유리 소성막은 유리 벌크와 비교하여 에칭속도가 최대 25배 빠른 것을 확인하였다. 유리 소성막의 표면 조도 값과 식각율 간의 통계학적으로 높은 상관성을 도출하였고, 이에 따라 소성막의 높은 표면조도가 빠른 식각을 유발하는 것으로 판단하였다. 그리고 유리 소성막은 Ca 성분의 함량이 적고, Si 함량이 많은 크리스토발라이트(cristobalite) 결정의 형성으로 인하여 Ca과 Ca 불화물에 의한 내플라즈마 효과가 감소한 것으로 판단된다. 따라서 CAS 유리 소성막은 유리 벌크에 비해 낮은 내플라즈마 특성을 갖는 것으로 판단된다.

• 한국세라믹학회지
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• 제52권6호
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• pp.395-402
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• 2015

The suspension plasma spray (SPS) technique has been used to obtain dense $Y_2O_3$ coatings and to overcome the drawbacks of the conventional air plasma spray (APS). SPS uses suspensions containing micrometer or sub-micrometer sized powders dispersed in liquid media. In this study, microstructure developments and mechanical properties have been investigated as functions of particle size of source material and plasma processing parameters such as plasma power and stand-off distance. The microstructure of the coating was found to be highly related to the particle size and the plasma processing parameters, and it was directly reflected in the hardness and the adhesion strength. When fine powder (BET $16.4m^2/g$) was used as a raw material in the suspension, there was, with increasing stand-off distance, a change from a dense structure with a slightly bumpy surface to a porous structure with a cauliflower-like surface. On the other hand, when a coarse powder (BET $2.8m^2/g$) was used, the coating density was lower, with microscopic splats on the surface. Using fine $Y_2O_3$ powders, the coating layer with an optimum short stand-off distance showed a high hardness of approximately 90% of that of sintered $Y_2O_3$ and an adhesion strength several times higher than that of the coating by conventional APS.

• 한국표면공학회지
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• 제50권5호
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• pp.366-372
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• 2017

Plasma electrolytic oxidation(PEO) has attracted attention as a surface treatment which has high wear resistance and corrosion resistance. PEO is generally considered as cost-effective, environmentally friendly and superior in terms of coating performance. Most of studies about the PEO processes have been applied to light metals such as Al and Mg. Because the strength of Al and Mg is weaker than that of steel, there is a limit to the application. In this study, PEO process was used to form oxide coatings on Hot dipped aluminized(HDA) steel and the characteristics of the coating film according to the PEO current density were studied. The morphology was observed by SEM and component was analyzed by using EDS. The corrosion behaviors of PEO coating films were estimated by exposing salt spray test at 5 wt.% NaCl solution and measuring polarization curves in deaerated 3 wt.% NaCl solution. With the increase of PEO process current density, the pore size of the coating surface and the thickness of coating increased. It was confirmed that no Fe component was present on the coating surface. PEO coating films obviously showed good corrosion resistance compared with HDA. It is considered that the PEO coating acts as a barrier to protect the base material from external factors causing corrosion.

• 한국표면공학회지
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• 제38권1호
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• pp.1-6
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• 2005

Ni-15at.% W coatings with film thicknesses of 20-40 ㎛ were electroplated on a steel substrate, and their oxidation behavior was investigated at 700 and 800℃ in air. For comparison, a pure Ni coating and a bulk Ni were also oxidized. The Ni-15at.%W coating displayed the worst oxidation resistance, due to the formation of less-protective NiO, Fe₂O₃, NiFe₂O₄ and NiWO₄. The corrosion behavior Ni-15at.%W coatings electroplated on a steel substrate was similarly investigated at 700 and 800℃ in the Ar-l%SO₂ atmosphere. For comparison, the uncoated steel substrate was also corrosion-tested in the Ar-l %SO₂ atmosphere. Severe scale spallation and the internal corrosion of the steel that occurred in the uncoated substrate were not observed in the coated specimen. However, it seemed that the Ni-15at.%W coating cannot be a potential candidate as a sulfidation-resistant coating, due to the formation of less-protective NiO, NiS, WO₃ and NiWO₄.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.299-299
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• 2013

Indium Tin Oxide (ITO) has widely been used as a transparent conductive oxide (TCE) for photovoltaic devices. Lately, flexibility of ITO becomes an issue as demand of flexible device increases. Several scientists have tried to substitute ITO to different materials such as conductive polymer, graphene, CNT, and metal nanowire because of ITO brittleness. Among the substitute materials, PEDOT:PSS has mostly paid attention because PEDOT:PSS has excellent flexibility and good conductivity. The conductivity of PEDOT:PSS increases up to 1000 S/cm with additives such as DMSO, EG, sorbitol, and so on. In our research group, we introduce a conductive polymer PEDOT:PSS as a buffer layer to improve not only flexibility but also conductivity. As PEDOT:PSS layer forms beneath ITO thin film (20 nm), sheet resistance decreases from $230{\Omega}$/${\Box}$ to $85{\Omega}$/${\Box}$ and crack initiation decreases from 4.5 mm to 3.5 mm as well. We have fabricated organic photovoltaic device and power conversion efficiencies using conventional ITO electrode and ITO/PEDOT:PSS hybrid electrode. The photovoltaic property such as power conversion efficiency for ITO/PEDOT:PSS hybrid electrode is comparable to the value obtained using conventional ITO electrode on glass substrate.

• 한국해양공학회지
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• 제12권3호통권29호
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• pp.49-59
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• 1998

The damage mechanism of $Cr_2O_3$ plasma coated soda-lime glass and uncoated glass by steel ball particle impact was analyzed in this study. And the shape variation of the cracks was investigated by stereo-microscope according to the impact velocity and steel ball diameter. In order to improve the damage reduction effect by $Cr_2O_3$ coating layer, crack size was measured and surface erosion state was observed for both of two kinds of specimen after impact experiment. And the results were compared with each other. The 4-point bending test was performed according to ASTM D790 testing method to evaluate the effect of coating layer for bending strength variation. As a result, it was found that the crack size of $Cr_2O_3$ coated specimen was smaller than that of uncoated one, because of the impact absorption by interior pores in the coating layer and the load dispersion by the structural characteristic of the coating layer. For the specimens subjected to the steel ball impact, the bending strength of coated specimen was higher than that of uncoated specimen.

• 한국세라믹학회지
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• 제45권12호
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• pp.777-781
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• 2008

Experiments were conducted using SUS430 and Crofer 22 APU steels coated by LSM using plasma spray and slurry spray methods, respectively. High-temperature conductivity and oxidation resistance were investigated. For comparison, SUS430 and Crofer 22 APU without LSM coating were also investigated and coefficient of thermal expansion (CTE) was measured. The results show that the materials without LSM coating exhibit almost the same CTE as YSZ electrolyte in a range of temperatures of $550{\sim}850^{\circ}C$. When coated with LSM, the oxidation rate of the steels decreases by $30{\sim}40%$ using slurry spray and by $10{\sim}30%$ using plasma spray whereas the steels using plasma spray have a better high-temperature conductivity than the steels using slurry spray. It is thus concluded that the LSM coating has a limited effect on increasing high-temperature conductivity while it can effectively reduce the oxidation of the steels.