• Korean Journal of Materials Research
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• v.16 no.11
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• pp.681-686
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• 2006

Plasma nitrocarburising and plasma post oxidation were performed to improve the wear and corrosion resistance of S45C and SCM440 steel by a plasma ion nitriding system. Plasma nitrocarburizing was conducted for 3h at $570^{\circ}C$ in the nitrogen, hydrogen and methane atmosphere to produce the ${\varepsilon}-Fe_{2-3}$(N, C) phase. Plasma post oxidation was performed on the nitrocarburized samples with various oxygen/hydrogen ratio at constant temperature of $500^{\circ}C$ for 1 hour. The very thin magnetite ($Fe_3O_4$) layer $1-2{\mu}m$ in thickness on top of the $15{\sim}25{\mu}m$ ${\varepsilon}-Fe_{2-3}$(N, C) compound layer was obtained by plasma post oxidation. A salt spray test and electrochemical testing revealed that in the tested 5% NaCl solution, the corrosion characteristics of the nitrocarburized compound layer could be further improved by the application of the superficial magnetite layer. Throttle valve shafts were treated under optimum plasma processing conditions. Accelerated life time test results, using throttle body assembled with shaft treated by plasma nitrocarburising and post oxidation, showed that plasma nitrocarburizing and plasma post oxidation processes could be a viable technology in the very near future which can replace $Cr^{6+}$ plating.

• Metals and materials international
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• v.24 no.6
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• pp.1309-1314
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• 2018

In this study, we investigated the state of $Y_2O_3$, as a major additive element in Fe-based ODS alloys, during mechanical alloying (MA) processes by thermodynamic approaches and experimental verification. For this purpose, we introduced $Ti_2O_3$ that formed different reaction products depending on the state of $Y_2O_3$ into the Fe-based ODS alloys. In addition, the reaction products of $Ti_2O_3$, Y, and $Y_2O_3$ powders were predicted approximately based on their formation enthalpy. The experimental results relating to the formation of Y-based complex oxides revealed that $YTiO_3$ and $Y_2Ti_2O_7$ were formed when $Ti_2O_3$ reacted with Y; in contrast, only $Y_2Ti_2O_7$ was detected during the reaction between $Ti_2O_3$ and $Y_2O_3$. In the alloy of $Fe-Cr-Y_2O_3$ with $Ti_2O_3$, $YTiO_3$ (formed by the reaction of $Ti_2O_3$ with Y) was detected after the MA and heat treatment processes were complete, even though $Y_2O_3$ was present in the system. Using these results, it was proved that $Y_2O_3$ decomposed into monoatomic Y and O during the MA process.

• Journal of Powder Materials
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• v.28 no.5
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• pp.396-402
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• 2021

Stainless steel, a type of steel used for high-temperature parts, may cause damage when exposed to high temperatures, requiring additional coatings. In particular, the Cr₂O₃ product layer is unstable at 1000℃ and higher temperatures; therefore, it is necessary to improve the oxidation resistance. In this study, an aluminide (Fe₂Al₅ and FeAl₃) coating layer was formed on the surface of STS 630 specimens through Al diffusion coatings from 500℃ to 700℃ for up to 25 h. Because the coating layers of Fe₂Al₅ and FeAl₃ could not withstand temperatures above 1200℃, an Al₂O₃ coating layer is deposited on the surface through static oxidation treatment at 500℃ for 10 h. To confirm the ablation resistance of the resulting coating layer, dynamic flame exposure tests were conducted at 1350℃ for 5-15 min. Excellent oxidation resistance is observed in the coated base material beneath the aluminide layer. The conditions of the flame tests and coating are discussed in terms of microstructural variations.

• Journal of The Korean Society of Agricultural Engineers
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• v.58 no.3
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• pp.39-46
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• 2016

This study investigated the potential use and the effectiveness of biomass ashes for the stabilization of heavy metals in soil through a series of experiments. The ashes used for the experiments were obtained from the gasification of biomass including miscanthus and woodchips. The amounts of nickel and chromium released from the soil and ash mixture were analyzed. Chemical analysis showed that the ash contained unburned carbon as well as silica and alkali metals. Miscanthus ashes have C (83.400 %) > Si (9.040 %) > K (3.180 %) > Ca (1.800 %), and woodchip ashes have C (93.800 %) > Ca (2.220 %) > Fe (1.370 %) > K (1.200 %). KSLT and TCLP test results implied that the heavy metal concentrations were below the environmental standards and would not impose the risks. The results also showed that Ni releases were more limited as more ashes were mixed with the soil due to the increases in exchangeable, carbonate, and oxide nikels. Both miscanthus and woodchip ahses were effective in stabilizing nickel and chromium through mixing with the soil. It could be seen that ashes produced from biomass gasification can be used to stabilize the heavy metals in soils.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2008.11a
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• pp.297-299
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• 2008

시화호 주변 해역에 서식하는 진주담치 내의 위생세균 및 비소(As), 카드뮴(Cd), 크롬(Cr), 철(Fe), 수은(Hg), 망간(Mn), 니켈(Ni), 납(Pb), 셀렌니움(Se) 및 아연(Zn)등의 미량원소들을 분석한 결과를 요약하면 다음과 같다. 본 연구해역의 전 조사정점에서 위생세균이 다소 높은 농도를 보이는 것은 아마도 조사시기가 하계로써 담수유입에 따른 영향으로 보여진다. 미량금속의 농도는 우리나라 식품위생기준 이내의 양호한 농도분포를 보였으며, 비소(As), 크롬(Cr), 니켈(Ni) 및 납의 경우 시화호 및 시화호 외측해역에서 유의한 농도차이(p<0.05)를 나타내지 않았으나 카드뮴 및 망간의 농도의 경우 시화호내에서 다소 높은 농도를 보였다(p<0.05). 반면에 구리, 수은, 셀렌니움 및 아연 등의 농도는 시화호에서 보다 시화호 외측해역에서 다소 높은 농도를 보였다(p<0.05). 또한 각성분간에 상관관계를 살펴보면 비필수원소중 수은과 카드물의 경우 셀레니움과 좋은 정의 상관성를 보이는 것으로 보아 이들 비필수원소의 셀레니움이 진주담치의 황산화성물질로 작용하는 것으로 보여 진다.

• Journal of the Korean Society of Costume
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• v.55 no.8 s.99
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• pp.154-160
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• 2005

For the purpose of standardization and practicability of natural dyeing, the mordanting and dyeing properties of Puerariae Radix was studied. Appropriate extraction, dyeing and mordanting condition of Puerariae Radix were determined, and the effect of mordanting method on dye uptake and color fastness of dyed fabric was investigated. The maximum absorbance of Puerariae Radix solution was at 290nm and 301nm. The pH effect was stable in the color difference changes. The optimum temperature to extract Puerariae Radix was during 1 hour in loot. The effective dyeing temperature and time of silk were 80$\~$ 100$^{circ}C$, 1hour. The silk fabrics dyed with Puerariae Radix appeared yellow-brown. US value of dyeing fabrics was increased by Fe, and Cu mordant treatment. Mordanting treatment method affected color change of the dyed silk. In the case of Puerariae Radix light fastness of appeared more than 2-5 grades by mordant treatment. Perspiration fastness of appered more than 4 grades by Al, Sn, Cr mordant treatment. Fastness of abrasion and dry-cleaning appered more than 4-5 grades. These fastness improvement were generally effective for mordant treatment, specially Al, Sn, Cr.

• Textile Coloration and Finishing
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• v.11 no.5
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• pp.30-37
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• 1999

The extracts drawn out from Artemisia princeps by water was concentrated. Using this concentrate the silk and the cotton fabrics were dyed, and they were measured with the K/S value, surface color and mordant quantity in order to evaluate the dyeability and the antimicrobial activity. The results are as follows; 1. The K/S value of the silk fabric was much higher than that of the cotton fabric. And the color yield of the dyed silk fabric was most efficient for the premordanting method. 2. The surface colors on the dyed fabric depended heavily upon mordants used or mordanting methods. For all cases, the value of the dyed fabric was generally dark. For the Cr-mordant among various mordants, the chroma produced clear and the color difference was distinct when using the Fe-mordant. 3. On the other hand the amount of absorbed mordant in the silk fabric was larger than that of the cotton fabric. And the Cu-mordant was most efficient. 4. The color fastness was significantly improved when mordants were added. Cr-mordant improved best in all of the dry cleaning, wet cleaning and perspiration fastness. Iron and abrasion fastness showed over 4-5 grade regardless of any mordant. And light fastness was best in Cu-mordant. 5. The Cu-mordant showed the greatest antimicrobial activity in both of mordant treat silk and cotton fabrics.

• Journal of Environmental Impact Assessment
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• v.10 no.2
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• pp.85-98
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• 2001

This study was conducted to investigate the geochemical factors governing the distribution of heavy metals(Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) in the marine surface sediment samples collected from the Samcheonpo coal-fired power plant. Variations of absolute metal concentrations were related to those in textural and/or carbonate and organic matter content. Most elements, except for Pb, showed generally lower contents compared with the average shale concentration, and the effect of anthropogenic input appeared to be minimal in the sediments. Computations of LF%(labile fraction) and EF(enrichment factor) based on all trace metal data indicated the presence of mineralogical control for Co, Cr, Cu, Ni, and Zn, and anthropogenic contamination for Pb, which needs to be considered in the design of long term monitoring programmes.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.646-648
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• 2008

The multi-films of a metallic film and a transparent conducting oxide (TCO, indium-tin oxide, ITO) film were formed on the stainless steel 316 and 304 plates by a sputtering method and an E-beam method and then the external metallic region of the stainless steel bipolar plates was converted into the metal nitride films through an annealing process. The multi-film formed on the stainless steel bipolar plates showed the XRD patterns of the typical indium-tin oxide, the metallic phase and the metal substrate and the external nitride film. The XRD pattern of the thin film on the bipolar plates modified showed two metal nitride phases of CrN and $Cr_2N$ compound. Surface microstructural morphology of the multi-film deposited bipolar plates was observed by AFM and FE-SEM. The electrical resistivity of the stainless steel bipolar plates modified was evaluated.

• Korean Journal of Materials Research
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• v.17 no.6
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• pp.308-312
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• 2007

Chromium oxide thin films have been deposited on silicon substrates using a tabletop 9kJ mathertyped plasma focus (PF) device. Before deposition, pinch behavior with gas pressure was observed. Strength of pinches was increased with increasing working pressure. Deposition was performed at room temperature as a function of working pressure between 50 and 1000 mTorr. Composition and surface morphology of the films were analyzed by Auger Electron Spectroscopy and Scanning Electron Microscope, respectively. Growth rates of the films were decreased with pressure. The oxide films were polycrystalline containing some impurities, Cu, Fe, C and revealed finer grain structure at lower pressure.