• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2015년도 춘계학술대회 논문집
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• pp.122-122
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• 2015

Al-rich coatings were prepared on hot rolled low carbon steel by hot dipping method in molten Al-bath to investigate the corrosion resistance with the possible outcomes and defects of aluminized coatings in air and $Ar-0.2%SO_2$ mixed gases. Coating microstructure was composed of an inner Al-Fe intermetallic layer and outer Al-rich layer. Aluminum oxidized preferentially to the thin, outer, protective ${\alpha}-Al_2O_3$ layer, without forming the nonprotective iron/sulfur-oxide layer after heating at $800^{\circ}C$ for 20h, in both the gases and provided the resistance against corrosion.

• Journal of Industrial and Engineering Chemistry
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• 제68권
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• pp.140-145
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• 2018

Bulky carbon layer uniformly distributed with nanoscale $Fe_2O_3$ was prepared via a direct carbonation of $Fe^{3+}$-polyacrylonitrile complexes at $700^{\circ}C$ under $N_2$ flow. The iron oxide carbon composites exhibited an excellent cycling performance for lithium storage with a reversible capacity of ${\sim}810mAh\;g^{-1}$ after 250 cycles at a current rate of $100mA\;g^{-1}$. The enhancement was mainly attributed to dual functions of bulky carbon layer which facilitated the lithium-ion diffusion and accommodated the volume changes of active $Fe_2O_3$ during charge/discharge process. Our novel chemical strategy is quite effective for scalable fabrication of high capacity lithium-storage materials.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 학술대회 논문집 전문대학교육위원
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• pp.22-25
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• 2000

Time dependent ozone generation characteristics of some oxide layers grown by ozone on the surface of corona discharge wires have been investigated experimentally in air ambience. Four wires of stainless steel, iron, silver and copper were used for the corona discharge wire of an ozone generator. And the effect of the metal oxide layers on ozone generation was studied and the contamination morphology of each layers was characterized. With the SEM images and the EDS spectra, it was found that all the surface of the corona wire were oxidized by the generated ozone and contaminated by airborne particles through the gradient force. As a result, the morphology and the electrical property of metal oxide layer grown on corona wire surface influenced on ozone generation characteristics i.e. discharge mechanisms.

• Corrosion Science and Technology
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• 제15권5호
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• pp.209-216
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• 2016

In the present study, chitosan based self-healing anticorrosion coatings were prepared by layer by layer (lbl) addition of chitosan (Ch) and polyvinyl butyral (PVB) on mild carbon steel substrate. Chitosan coatings exhibited enhanced coating stability and corrosion resistance in aggressive environments by the application of a PVB top layer. Chitosan layer in the lbl coatings have been modified by using glutaraldehyde (Glu) and silica ($SiO_2$). Performance of different coatings was tested using electrochemical impedance spectroscopy and immersion test. The best anticorrosion performance was observed in case of 10 % Ch_$SiO_2$_PVB coatings, which withstand immersion test over 25 days in 0.5 M salt solution without visible corrosion. 10 % Ch_$SiO_2$ coatings without the PVB top layer didn't last more than 3days. Application of PVB top layer sealed the defects in the chitosan pre-layer and improved its hydrophobic nature as well. Raman spectra and SEM of steel surfaces after corrosion study and removal of PVB_Ch/Glu_PVB coatings showed a passive layer of iron oxide, attributing to the self-healing nature of these coatings. Conducting particle like graphene reinforcement of chitosan in the lbl coatings enhanced corrosion resistance of chitosan coatings.

• 자원환경지질
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• 제43권6호
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• pp.543-553
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• 2010

이 연구는 부여 정동리 꿩바윗골 유적에서 출토된 백제시대 경작토양의 광물학적 및 지구화학적 특정을 조사하고, 이를 사용하여 제작한 것으로 추정되는 무령왕릉 및 송산리 전(벽돌)과 토양을 비교하여 태토로서의 가능성을 검토하였다. 연구대상 토양시료들은 모두 미사질 양토로 가장 하부층을 제외하고는 모두 유사한 토양입도를 가지고 있다. 토양은 산성으로 일부 시료에서 유기물, P, S 등의 집적현상이 나타났다. 또한 지구화학적 원소 분포경향이 유사하며 석영, 사장석, 정장석, 질석, 운모, 고령석 등으로 구성되어 동일한 광물조성을 보인다. 부분적으로 붉은 철산화물의 농집이 관찰되는데, 강의 범람과 배수에 따른 산화와 환원환경이 반복되었던 환경이 토양 내 철산화물의 농집을 일으킨것으로 보인다. 이는 자연현상과 인간의 경작활동에 의한 풍화양상으로 볼 수 있다. 특히 무령왕릉과 송산리고분군 출토 전에서 발견되는 철산화물의 농집현상은 연구지역 토양이 전의 태도로 추정될 수 있는 추가적인 증거로 판단된다.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2007년도 The 1st International Symposium on Advanced Magnetic Materials
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• pp.133.1-133.1
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• 2007

• 열처리공학회지
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• 제12권1호
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• pp.31-39
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• 1999

In the present study, oxidation behavior of 304 and 316 stainless steels was investigated. After solution treatment, specimens were polished up to $1{\mu}m$ $Al_2O_3$ grade and then subjected to oxidation treatment in dry air. The range of temperature was used for oxidation treatment at $300^{\circ}C{\sim}500^{\circ}C$ and TEM was used for analyzing the components and structure of oxide film. Also, these results were compared with the results of ESCA and TG. According to the results of TEM analysis, it was found that Cr oxide film was formed on top of the surface after room temperature oxidation but amorphous Fe oxide was formed on top of the surface and polycrystalline $(Cr,Fe)_2O_3$ was formed below the amorphous Fe oxide layer after $500^{\circ}C$ oxidation treatment. The oxidized specimens at $500^{\circ}C$ showed that 316 stainless steel resists more strongly to grain and grain boundary oxidation than 304 stainless steel. These results suggested that Mo component resolved in 316 stainless steel matrix suppressed the formation of Cr carbide which may results in local Cr deplete area.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.1124-1125
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• 2006

Dry sliding wear behavior of electro-pressure sintered Co-Fe, Co-Ni and Co-Fe-Ni compacts was investigated. Pin-on-disk wear tests were performed on the sintered compacts disk specimens against alumina $(Al_2O_3)$ and silica $(SiO_2)$ ball counterparts at various loads ranging from 3N to 12N. Two sliding speeds of 0.1m/sec and 0.2m/sec and a fixed sliding distance of 1,000m were employed. Worn surfaces and cross sections of them were examined by a scanning electron microscopy, and wear mechanism of the compacts was investigated. Effects of the oxide layer that was formed on wearing surface of the compacts on the wear were also studied.

• 한국세라믹학회지
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• 제20권3호
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• pp.211-216
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• 1983

This work aims at characterizing silicon grains and its compacts. In order to remove iron silicon grains were washed with 5N hydrochloride at 60-7$0^{\circ}C$ for 170 hrs, and then followed the chemical analysis by atomic absorption spectrophotometer X-ray diffraction analysis SEM observation and specific surface area determination by B. E. T. Mixtures of graded silicon particles with two or three different sizes were made into packings by mechanical vibration. The mixtures were used to make compacts with 10 mm in diameter and 70mm in length by isostatically pressing at 1, 208 kg/$cm^2$ (20 kpsi) and 4, 255kg/$cm^2$ (60 kpsi) respectively. Bulk densities of packings and compacts were measured. A slip made of magnesium nitrate solution and fine silicon particles was spray-dried and then decomposed at 30$0^{\circ}C$ for the purpose of coating the uniform layer of magnesium oxide on the surface of particles. The results obtained are as follows: (1) About two thirds of iron content could be removed from silicon by washing silicon powders with hydrochloride. (2) Uniform layer of magnesium oxide on the surface of silicon could be prepared by spray-drying suspension and by decomposing it. (3) B. E. T. specific surface area of fine silicon particles was 2, 826.753$m^3$/kg. (4) In the binary system with two sizes of 40-53$\mu\textrm{m}$ particles and <10$\mu\textrm{m}$ particles the maximum bulk density of packing was 55% of theoretical value and that of compacts made at the pressure of 4, 255 kg./$cm^2$ (60 kpsi) was 73% of theoretical value. (5) In the ternary system with three sizes the maximum bulk density of packing was 1.43 g/$cm^3$and that of compacts was 1.80g/$cm^3$which is equivalent to 77.6% of theoretical value. The composition of the closest compact was consisted of 50% of 40-53$\mu\textrm{m}$ particles 20% of 10-30$\mu\textrm{m}$ particles and 30% of <10$\mu\textrm{m}$ parti-cles.

• 한국자기학회지
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• 제2권1호
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• pp.15-21
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• 1992

침상형의 ${\gamma}-Fe_{2}O_{3}$ 입자를 $Co^{+2}/Fe^{+2}$의 몰비가 0.5인 2가 금속혼합용액을 함유하는 알카리성 용액에서 $90^{\circ}C$로 가열하였다. 코발트 함량이 증가함에 따라 생성물의 보자력은 거의 직선적으로 증가하였으며 비표면적은 감소하였다. 코발트 훼라이트는 ${\gamma}-Fe_{2}O_{3}$ 결정 표면상에 에피탁시얼하게 성장되며, 보자력의 증가는 피착층인 코발트 훼라이 트의 결정 자기이방성에 기인하는 것으로 사료된다. 당량비 2이상에서 우수한 자기적 특성을 기대할 수 있 었으며 반응공정도 코발트 훼라이트 에피탁시얼 산화철의 보자력 특성에 영향을 미친다. $Co-{\gamma}-Fe_{2}O_{3}$의 온도 및 경시변화에 대한 안정성은 피착층 조성에 의해 크게 지배된다.