• Corrosion Science and Technology
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• 제21권1호
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• pp.53-61
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• 2022

Alloys of Fe-(5.3-29.8)%Mn-(1.1-1.9)%Al-(0.4-0.5)%C were oxidized at 550 ℃ to 650 ℃ for 20 h to understand effects of alloying elements on oxidation. Their oxidation resistance increased with increasing Mn level to a small extent. Their oxidation kinetics changed from parabolic to linear when Mn content was decreased and temperature was increasing. Oxide scales primarily consisted of Fe₂O₃, Mn₂O₃, and MnFe₂O₄ without any protective Al-bearing oxides. During oxidation, Fe, Mn, and a lesser amount of Al diffused outward, while oxygen diffused inward to form internal oxides. Both oxide scales and internal oxides consisted of Fe, Mn, and a small amount of Al. The oxidation of Mn and carbon transformed γ-matrix to α-matrix in the subscale. The oxidation led to the formation of relatively thick oxide scales due to inherently inferior oxidation resistance of alloys and the formation of voids and cracks due to evaporation of manganese, decarburization, and outward diffusion of cations across oxides.

• Environmental Engineering Research
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• 제14권2호
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• pp.134-139
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• 2009

In this study, oxidation of As (III) as well as removal of total arsenic by adsorbents coated with single oxides or multi-oxides (Fe (III), Mn (IV), Al (III)) was investigated. In addition, multi-functional properties of adsorbents coated with multi-oxides were evaluated. Finally, application of activated carbon impregnated with Fe or Mn-oxides on the treatment of As (III) or As (V) was studied. As (V) adsorption results with adsorbents containing Fe and Al shows that adsorbents containing Fe show a greater removal of As (V) at pH 4 than at pH 7. In contrast adsorbents containing Al shows a favorable removal of As (V) at pH 7 than at pH 4. In case of iron sand, it has a negligible adsorption capacity for As (V) although it contains 217.9 g-Fe/kg-adsorbent, Oxidation result shows that manganese coated sand (MCS) has the greatest As (III) oxidation capacity among all metal oxides at pH 4. Oxidation efficiency of As (III) by IMCS (iron and manganese coated sand) was less than that by MCS. However the total removed amount of arsenic by IMCS was greater than that by MCS.

• 한국수소및신에너지학회논문집
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• 제14권3호
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• pp.268-275
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• 2003

The water-splitting process by the metal oxides using solar heat is one of the hydrogen production method. The hydrogen production process using the metal oxides (NiFe2O4/NiAl2O4,CoFe2O4/CoAl2O4, CoMnNiFerrite, CoMnSnFerrite, CoMnZnFerrite, CoSnZnFerrite) was carried out by two steps. The first step was carried out by the CH4-reduction to increase activation of metal oxides at operation temperature. And then, it was carried out the water-splitting reaction using the water at operation temperature for the second step. Hydrogen was produced in this step. The production rates of H2 were 110, 160, 72, 29, 17, $21m{\ell}/hr{\cdot}g-_{Metal\;Oxide}$ for NiFe2O4/NiAl2O4, CoFe2O4/CoAl2O4, CoMnNiFerrite, CoMnSnFerrite, CoMnZnFerrite, CoSnZnFerrite respectively in the second step. CoFe2O4/CoAl2O4 had higher H2 production rate than the other metal oxides.

• 한국토양비료학회지
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• 제37권6호
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• pp.371-377
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• 2004

산림토양에서의 황산이온 흡착은 식물의 흡수, 양이온 이동 및 산중화능 등 산림생태계의 황 동태에 중요한 영향을 미친다. 따라서 본 연구는 산림토양 중의황산이온 분포와 그와 관련된 황산이온 흡착이 어떠한 토양특성에 의해 영향을 받는지를 밝히기 위해 수행되었다. 이를 위해 소나무와 신갈나무 임분으로 조성된 4개 산림지역을 대상으로 표토층과 심토층으로 구분하여 황산이온 흡착지표로서의 추출성 황산이온함량 및 황산이온 흡착능을 정량 한 후 관련 토양 물리화학적 특성인 pH. 양이온치환용량, 점토함량 및 Ai과 Fe 산화물의 종류별 함량과의 상관성을 분석하였다. 토양 중 추출성 황산이온 함량 및 황산이온 흡착능은 각 조사지별로 큰 차이를 보였으며 전체적으로 유기물 함량이 적고 Al 또는 Fe 산화물 함량은 많은 심토층이 표토층에 비하여 황산이온 흡착량이 많았다. 황산이온 흡착량이 많았던 심토층의$Al_d$와 $Fe_d$ 산화물 평균 함량은 각각 8.49와 $12.45g\;kg^{-1}$로 대체로 낮은 수준이었다. 황산이온 흡착지표들은 토양 pH, 양이온치환용량 및 점토함량과 대체로 유의적인 정의 상관관계를 보였다. 반면에 유기탄소 함량과는 부의 상관성을 보여 산림토양 중에서 유기물이 황산이온 흡착에 대해 경합물질로 작용함을 알 수 있었다. Ai과 Fe 산화물 중에서는 $Al_d,\;Al_o,\;Al_p,\;Al_a$ 및 $Fe_a$가 황산이온 흡착지표들과 유의성 있는 상관성을 보였으나, $Al_c$와 $Fe_c$는 황산이온 흡착지표들과 상관성이 없었다. 황산이온 흡착지표인자들과 토양 pH, 양이온치환용량 및 비결정형 Ai 함량간의 정의 상관관계 결과는 토양산성화로 인해 산림생태계에서 황 동태에 기여하는 산림토양의 황산이온 흡착 능력이 저하될 수 있음을 반영한다.

• 한국재료학회지
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• 제14권8호
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• pp.547-551
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• 2004

The sulfidation behaviour of Fe-XAl-0.3Y(X=5, 10, 14, 25 $wt.\%$) alloys was investigated at 1123 K in $H_2/H_{2}S$ gas atmosphere for $1\sim24$ hrs using SEM/EDX, XRD and EPMA. The weight changes of Fe-XAl-0.3Y alloys followed the parabolic rate law, Sulfidation rates of iron aluminide alloys with high Al content were one-twentieth lower than that of 5Al alloys. This is due to the formation of protective $Al_{2}O_3$ oxides on the surface of 10Al, 14Al and 25Al alloys. By calculating partial pressure of impurity oxygen contained $H_2/H_{2}S$ gas, the $Al_{2}O_3$ oxides formation could be explained using Fe-Al-S-O thermodynamic stability diagram. The sulfidation product scales of the 5Al alloy showed that thick iron sulfide scale(FeS) containing porosities formed during early stages of sulfidation. With continued sulfidation, aluminum sulfide was formed at the alloy/scale interface.

• 열처리공학회지
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• 제13권3호
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• pp.158-162
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• 2000

The high temperature oxidation behavior and the surface defect in Fe-25Mn-1.5A1-0.5C steel was investigated by XRD (X-ray Diffractin) and electron microscopy. The intra- and inter-granular oxides were formed by the selective oxidation of manganese and aluminum, which were identified to MnAl2O4 phase. Aluminum nitride (AlN) was formed in front of these oxides. The ${\gamma}$-matrix was transformed to ${\alpha}$- and ${\varepsilon}$- phases by the selective oxidation of manganese. The surface defect, micro-scab was induced by the difference of the high temperature ductility between the matrix and the inter-granular oxide.

• 한국재료학회지
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• 제13권12호
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• pp.791-795
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• 2003

The oxidation behaviour of Fe-XAl-0.1Y(X= 5, 10, 14 wt.%) alloys were investigated at 1073, 1173 and 1273 K in oxygen/ nitrogen gas atmosphere for 1∼24 hrs using SEM/EDX, XRD and EPMA. The weight changes of Fe-XAl-0.1Y alloys followed the parabolic rate law. Oxidation rates of 10Al and 14Al alloys were ten times lower than that of 5Al alloys. This is attributed to the formations of protective $A1_2$$O_3$oxides on the surface of 10Al and 14Al alloys. The oxidation product scales of the 5Al alloy showed that thick iron oxide scales($Fe_2$$O_3$, $Fe_3$$O_4$) containing porosities formed during early stages of oxidation. With continued oxidation, aluminum oxide was formed at the alloy/scale interface.

• Corrosion Science and Technology
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• 제7권2호
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• pp.112-118
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• 2008

We observed initial rusting process of steel containing Al under wet/dry cyclic condition with NaCl solution film using in situ X-ray diffraction spectroscopy at SPring-8 synchrotron radiation facility. It was found that mass fraction of iron oxides such as ${\alpha}-FeOOH$, ${\beta}-FeOOH$ and ${\gamma}-FeOOH$ varied with Al content. Some kinds of Al oxides were also found at the initial stage of corrosion. Those corrosion products might affect the corrosion process and corrosion rate of the steel.

• 공업화학
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• 제20권5호
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• pp.522-526
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• 2009

다양한 금속(Ru, Mn, Co, Fe)을 $Al_2O_3$와 $CeO_2$에 담지한 촉매를 이용하여 1,2-Dichlorobenzen (1,2-DCB) 제거를 위한 촉매산화 실험을 실시하였다. 이와 더불어 동시에 NOx 제거가 이루어져 단일 촉매층에서 산화/환원 이원 기능이 가능한 촉매를 연구하고자 하였다. 실험결과 1,2-DCB 산화제거효율은 Ru/Co/$Al_2O_3$, Mn-Fe/$CeO_{2}$, 상용촉매인 Cr/$Al_2O_3$ 순으로 나타났다. 또한 1,2-DCB 산화제거효율이 가장 우수하였던 Ru/Co/$Al_2O_3$는 Chlorobenzene (CB)의 분해실험에서도 VOC 제거에 있어서 잘 알려진 Pt-Pd/$Al_2O_3$ 보다 우수한 활성을 나타내었다. 또한 $Cl_2$와 같은 생성물에 의하여 활성의 저하 및 황에 대한 내피독성과 내구성에서 우수한 결과를 얻을 수 있었다. NOx 제거에 있어서도 $260^{\circ}C$에서 NOx 전환율이 70% 정도로 나타났다.

• Corrosion Science and Technology
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• 제11권1호
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• pp.9-14
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• 2012

The formation of the Fe-Al inhibition layer in hot-dip galvanizing is a confusing issue for a long time. This study presents a characterization result on the inhibition layer formed on C-Mn-Cr and C-Mn-Si dual-phase steels after a short time galvanizing. The samples were annealed at $800^{\circ}C$ for 60 s in $N_{2}$-10% $H_{2}$ atmosphere with a dew point of $-30^{\circ}C$, and were then galvanized in a bath containing 0.2 %Al. X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) was employed for characterization. The TEM electron diffraction shows that only $Fe_{2}Al_{5}$ intermetallic phase was formed. No orientation relationship between the $Fe_{2}Al_{5}$ phase and the steel substrate could be identified. Two peaks of Al 2p photoelectrons, one from metallic aluminum and the other from $Al^{3+}$ ions, were detected in the inhibition layer, indicating that the layer is in fact a mixture of $Fe_{2}Al_{5}$ and $Al_{2}O_{3}$. TEM/EDS analysis verifies the existence of $Al_{2}O_{3}$ in the boundaries of $Fe_{2}Al_{5}$ grains. The nucleation of $Fe_{2}Al_{5}$ and the reduction of the surface oxide probably proceeded concurrently on galvanizing, and the residual oxides prohibited the heteroepitaxial growth of $Fe_{2}Al_{5}$.