• 대한금속재료학회지
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• 제48권10호
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• pp.907-913
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• 2010

Hot-rolled steel plates of SPHC and SS400 were oxidized at 600, 750 and $900^{\circ}C$ for 2 hr in air. With an increase in the oxidation temperature, their oxidation rates increased, and this was accompanied by the formation of pores and cracks in the thickened oxide scales, which were non-adherent. SPHC steels manufactured by either an arc furnace or a blast furnace displayed similar oxidation rates, indicating that their oxidation rates were insensitive to the manufacturing process. Medium-carbon SS400 steel displayed somewhat faster oxidation rates than low-carbon SS400 steel, indicating that the carbon content did not significantly influence the oxidation rates.

• 열처리공학회지
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• 제20권5호
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• pp.231-236
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• 2007

High velocity oxy-fuel (HVOF) spraying was used to coat Ti(Al,O)/$Al_2O_3$ powder onto the SS41 steel plate. Macrostructure of the coated specimen has been investigated by scanning electron micrograph (SEM). High temperature oxidation behavior of the coated specimen and SS41 steel have been studied. From the results of SEM observation, Ti(Al,O)/$Al_2O_3$ powder was coated well onto the substrate SS41 steel. Porosity onto the coated layer was only 0.38%. The oxidation results showed that Ti(Al,O)/$Al_2O_3$ powder coated SS41 steel have improved little oxidation resistance at $900^{\circ}C$ in air, but improved remarkably oxidation resistance at $800^{\circ}C $ in air compare to the substrate SS41 steel.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 추계학술대회 논문집 학회본부 C
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• pp.947-949
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• 1998

In this paper, the NO was oxidized $NO_2$ by using the non-thermal plasma and NOx removal characteristics were measured by showering NaOH water-solution to $NO_2$. The NO oxidation increased in the order of DC, AC, and Pulse. NOx oxidation for two stage with applied voltage was better than that for one stage with applied voltage. NO oxidation didn't depend on applied voltage. While NO oxidation was going on, NOx removal efficiency was 20-25%, however, significantly depended on the injection method of air and $H_2O$ + air. When NaOH water-solution density of 20% was showered to flue gases, NOx removal efficiency increased to 64%.

• Carbon letters
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• 제6권1호
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• pp.31-40
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• 2005

The carbon nanofibers (CNFs) were synthesized through the catalytic decomposition of hydrocarbons in a quartz tube reactor. The CNFs prepared from $C_3H_8$ at $550^{\circ}C$ was selected as the purification sample due to the higher content of impurity than that prepared from other conditions. In this study, we carried out the purification of CNFs by oxidation in air or carbon dioxide after acid treatment, and investigated the influence of purification parameters such as kind of acid, concentration, oxidation time, and oxidation temperature on the structure of CNFs. The metal catalysts could be easily eliminated from the prepared CNFs by liquid phase purification with various acids and it was verified by ICP analysis, in which, for example, Ni content decreased from 2.51% to 0.18% with 8% nitric acid. However, the particulate carbon and heterogeneous fibers were not removed from the prepared CNFs by thermal oxidation in air and carbon dioxide. This result can be explained by that the direction of graphene sheet in CNFs is vertical to the fiber axis and the CNFs are oxidized at about the similar rate with the impurity carbon.

• 한국표면공학회지
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• 제46권2호
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• pp.80-86
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• 2013

Magnesium alloys of AZ31 containing (0.5, 1, 1.5) wt.% of initially added CaO particles were cast in air, and their oxidation behavior was studied at $450-650^{\circ}C$ in air. The initially added CaO particles either decomposed to dissolve in the ${\alpha}$-Mg matrix or precipitated as $Al_2Ca$ along the grain boundaries of the matrix during casting. The ignition temperatures were $565.4^{\circ}C$ for AZ31, $608.6^{\circ}C$ for AZ31+0.5 wt.%CaO, and $689.7^{\circ}C$ for AZ31+1 wt.%CaO. No ignition occurred for AZ31+1.5 wt.%CaO up to $700^{\circ}C$, displaying good oxidation resistance. The CaO-rich oxide scales that formed on the surface of the AZ31+(0.5, 1, 1.5) wt.%CaO alloys improved the oxidation resistance of AZ31 alloys.

• 센서학회지
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• 제27권1호
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• pp.13-20
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• 2018

Gas sensors based on metal oxide semiconductors are used in numerous applications including monitoring indoor air quality and detecting harmful substances like volatile organic compounds. Nanostructures, for example, nanoparticles, nanotubes, nanodomes, and nanofibers have been widely utilized to improve gas sensing properties of metal oxide semiconductors, and this increases the effective surface area, resulting in participation of more target gas molecules in the surface reaction. In the recent times, 1-dimensional (1D) metal oxide nanostructures fabricated using anodic oxidation have attracted great attention due to their high surface-to-volume ratio with large-area uniformity, reproducibility, and capability of synthesis under ambient air and pressure, leading to cost-effectiveness. Here, we provide a brief overview of 1D metal oxide nanostructures fabricated by anodic oxidation and their gas sensing properties. In addition, recent progress on thin film-based anodic oxidation for application in gas sensors is introduced.

• 한국수산과학회지
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• 제16권4호
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• pp.349-354
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• 1983

송풍식건조에 의한 어육건조중의 변색에 미치는 공기의 상대습도의 영향을 검토한 결과를 요약하면 다음과 같다. $40^{\circ}C,\;55^{\circ}C$ 및 $70^{\circ}C$에서의 어육건조중 어육변색의 주된 원인은 지방산화였다. 지방함량이 높은 어육일수록 지방산화에 의한 변색이 심하였다. $40^{\circ}C$와 $55^{\circ}C$에서의 건조중에는 공기의 상대습도가 $30\%$ 정도일 때 지방산화가 가장 늦었으며, 상대습도가 $30\%$ 보다 낮아지거나 높아질수록 지방산화가 촉진되었다. $70^{\circ}C$에서의 건조중에는 상대습도의 지방산화에 대한 뚜렷한 영향이 확인되지 않았으며, 고온에서는 지방산화가 조조온도에 민감한 듯 하였다. Maillard반응에 의한 갈변은 건조중의 변색에는 큰 영향을 미치지 않았고, 상대습도 $10\%{\sim}50\%$의 범위에서는 상대습도가 높을수록 반응속도가 빨랐다.

• 한국수산과학회지
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• 제33권3호
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• pp.192-197
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• 2000

본 연구는 대멸치로 소건품을 제조하기 위하여 건조조건에 따른 수분함량의 변화와 지질의 산화를 조사하였다. 수분은 $60{\circ}C$ 열풍건조 (풍속 1.4 m/sec), $40{\circ}C$ 열풍건조 (풍속 1.4 m/sec), 천일건조 ($30{\pm}5{\circ}C$) 및 $20{\circ}C$ 냉풍건조 (풍속 3.1 m/sec)하였을 때 건조 7시간에 각각 $9.0{\%}, 34.0{\%}, 34.0{\%}, 38.8{\%}$의 함량을 나타내었다. 건조중 산가, 과산화물가, 카보닐가 및 지용성 갈변도는 건조온도가 높을수록 빠르게 증가하였으며, $20{\circ}C$ 냉풍건조하였을 때 지질의 산화가 가장 현저하게 억제되었다. 건조방법에 따른 지방산의 조성변화는 천일건조가 가장 라르고, 그 다음으로 $60{\circ}C$ 열중건조, $40{\circ}C$ 열풍건조, $20{\circ}C$ 냉풍건조의 순이었다. 건조 중 대멸치의 지방산 조성은 폴리엔산 (20 : 5, 22 : 6)은 감소하고 포화산 (14 : 0, 16 : 0)과 모노엔산 (16 : 1, 18 : 1)은 증가하였다. 대멸치의 적정 건조 조건은 온도 $20{\circ}C$, 상대습도 $30{\%}$ 정도에서 냉풍건조하는 것이 지질의 산화억제에 효과적이었다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2004년도 제5회 압연심포지엄 신 시장 개척을 위한 압연기술
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• pp.285-293
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• 2004

Oxidation behavior of 304 and 430 stainless steel were studied using thin film X-ray analysis and glow discharge spectrum analysis (here-after GDS). The oxidation layer of 304 stainless steel was composed of $Cr_2O_3\;and\;FeCrO_4$ and its thickness was about $1.5{\mu}m$ after $1\~5$ minutes of annealing at $1120^{\circ}C$ open air. However, the oxidation layer of 430 stainless steels was mainly composed of $Cr_2O_3$ and its typical thickness was 0.5um after $1\~5$ minutes of annealing at $1000^{\circ}C$ open air. Electro-chemical analysis revealed that the descaling of oxidation layer could be activated by Fe, Cr dissolution from the matrix behind the oxidation layer at the current density of $5\~10ASD$ and by Fe, Cr-oxide dissolution from the oxidation layer at the current density over than 10ASD. Electrolytic stripping of 430 and 304 revealed the intial incubation period of descaling by oxygen evolving at low current density range such as $5\~10ASD$. However the dissolution of oxide layer was occurred when applying the anodic current of $10\~20ASD$ on 430 and 304 stainless steels. It was suggested that the electrolytic pickling of high Cr bearing stainless steel such as 430 and 304 seemed to be the more effective in the high current density range such as $10\~20ASD$ than the low current density range such as $5\~10ASD$.

• Carbon letters
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• 제18권
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• pp.18-23
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• 2016

Polyacrylonitrile (PAN)-based carbon fibers have high specific strength, elastic modulus, thermal resistance, and thermal conductivity. Due to these properties, they have been increasingly widely used in various spheres including leisure, aviation, aerospace, military, and energy applications. However, if exposed to air at high temperatures, they are oxidized, thus weakening the properties of carbon fibers and carbon composite materials. As such, it is important to understand the oxidation reactions of carbon fibers, which are often used as a reinforcement for composite materials. PAN-based carbon fibers T300 and T700 were isothermally oxidized in air, and microstructural changes caused by oxidation reactions were examined. The results showed a decrease in the rate of oxidation with increasing burn-off for both T300 and T700 fibers. The rate of oxidation of T300 fibers was two times faster than that of T700 fibers. The diameter of T700 fibers decreased linearly with increasing burn-off. The diameter of T300 also decreased with increasing burn-off but at slower rates over time. Cross-sectional observations after oxidation reactions revealed hollow cores in the longitudinal direction for both T300 and T700 fibers. The formation of hollow cores after oxidation can be traced to differences in the fabrication process such as the starting material and final heat treatment temperature.