• Metals and materials international
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• v.28
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• pp.1778-1782
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• 2021

This study examines the insulation coating technology of Fe-Si-Cr powder via selective oxidation annealing, which oxidizes elements selectively by controlling the oxidation potential. The study calculated the oxidation driving force of Fe, Si, and Cr, and conducted a thermodynamic analysis of oxidation and reduction conditions according to temperature and oxidation potential. Based on the results, a selective oxidation annealing was performed in an atmosphere in which Fe is reduced and only Si and Cr are selectively oxidized. The oxidation potential was controlled through the partial pressure ratio of hydrogen and water vapor. The XPS analysis results confirmed that a Si and Cr complex oxide layer formed on the powder surface after the selective oxidation annealing. Afterward, withstanding voltages were analyzed to evaluate the insulation property. Then, the withstanding voltage of the powder applying the selective oxidation annealing increased significantly compared to that of the initial powder. Further analysis showed that the powder annealed in an air atmosphere had a significantly lower saturation magnetic flux density than the initial powder, while the powder applying the selective oxidation annealing had only a slightly reduced saturation magnetic flux density.

• Journal of Hydrogen and New Energy
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• v.18 no.1
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• pp.32-39
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• 2007

CO oxidation and selective CO oxidation of $La_xCe_{1-x}Co_yCu_{1-y}O_{3-{\alpha}}$ perovskite(x=1, 0.9, 0.7. 0.5; y=1, 0.9, 0.7, 0.5) were investigated. For CO oxidation, catalytic activities were studied according to different preparation conditions such as pH and calcination temperature. The influence of the change of the $O_2$ concentration for selective CO oxidation was studied, too. The substitution of Ce for La improved the catalytic activity for CO oxidation and selective CO oxidation and best activity was observed for $La_{0.7}Ce_{0.3}CoO_3$ prepared at pH 11 and calcined at $600^{\circ}C$. The temperature of 90% CO conversion for CO oxidation using $La_{0.7}Ce_{0.3}CoO_3$ was $230^{\circ}C$. In contrast to the enhancement effect by Ce substitution, the partial substitution of Cu for Co in $LaCo_yCu_{1-y}O_{3-{\alpha}}$ decreased catalytic activities for CO oxidation reaction compared to that using $LaCoO_3$. For selective CO oxidation, the best CO conversion was 66% at $230^{\circ}C$ for $La_{0.7}Ce_{0.3}CoO_3$. The CO conversion of $La_{0.7}Ce_{0.3}CoO_3$ was greatly increased from 66% to 91% as increasing $O_2$ concentration from 1% to 2%.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2001.10a
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• pp.269-274
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• 2001

This paper describes the experimental results on direct selective laser sintering of WC-Co mixture. The experiments were carried out within an air, argon and nitrogen atmosphere. The main problem occurred during sintering within an air atmosphere was oxidation of WC-Co mixture. As the power of laser is increased and scanning speed is decreased, more severe oxidation takes place. Within an argon and nitrogen atmosphere the oxidation is reduced significantly. As the energy density is increased the thickness of the sintered layer is increased.

• Journal of the Korean Chemical Society
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• v.56 no.5
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• pp.539-541
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• 2012

• Bulletin of the Korean Chemical Society
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• v.22 no.1
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• pp.120-122
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• 2001

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.6
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• pp.151-157
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• 1996

We propose a mechanism for the formation of pinholes in the Si-buffer layer, through the observations with varying the process- and structure variables in the SEPOX (selective poly-oxidation) process, an isolation method for sub-u DRAMs. Pinholes are formed through the accumulation of Si vacancies generated by the oxidation of Si, in which Si atoms leave the sites (vacancies) at the Si/SiO$_{2}$ interfaces and diffuse into the oxide to be oxidized near interface. In the course of the accumulation of Si-vacancies, the stress induced in the Si-buffer layer affects the migration of vacancies to result in the final size and distribution of pinholes. This paper may be, to our knowledge, the first report about the oxidation-induced pinhole in the Si/SiO$_{2}$ system.

• Journal of Microbiology and Biotechnology
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• v.23 no.5
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• pp.719-723
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• 2013

Nitrification in wastewater treatment emits a significant amount of nitrous oxide ($N_2O$), which is one of the major greenhouse gases. However, the actual mechanism or metabolic pathway is still largely unknown. Selective nitrification inhibitors were used to determine the nitrification steps responsible for $N_2O$ emission with activated sludge and enriched nitrifiers. Allylthiourea (86 ${\mu}M$) completely inhibited ammonia oxidation and $N_2O$ emission both in activated sludge and enriched nitrifiers. Sodium azide (24 ${\mu}M$) selectively inhibited nitrite oxidation and it led to more $N_2O$ emission than the control experiment both in activated sludge and enriched nitrifiers. The inhibition tests showed that $N_2O$ emission was mainly related to the activity of ammonia oxidizers in aerobic condition, and the inhibition of ammonia monooxygenase completely blocked $N_2O$ emission. On the other hand, $N_2O$ emission increased significantly as the nitrogen flux from nitrite to nitrate was blocked by the selective inhibition of nitrite oxidation.

• Electronic Materials Letters
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• v.18
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• pp.198-204
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• 2022

The design of the material synthesis process is important because this process can be applied to a variety of materials and used in different applications. Herein, we selectively oxidized two types of metals in a carbon nanofiber (CNF) support and then left only one type of metal on a porous support using selective etching. Ni and MgO were formed in the CNFs through annealing, and then MgO was etched with an HCl etchant. In the selective oxidation process, two types of metal were selected by considering the oxidation tendency between the metal and C. Ni was selected as an oxidant of C, and Mg was selected as a reductant of C. The two metals with significantly different oxidation tendencies were predicted to have different reactivity with the etchant, making them suitable for selective etching. The effectiveness of selective etching was verified by energy-dispersive X-ray spectroscopy (EDS) and transmission electron microscopy (TEM). In EDS, the atomic concentration of Mg was selectively reduced. In TEM, the formation of a porous structure was confirmed.

• Corrosion Science and Technology
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• v.10 no.1
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• pp.6-12
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• 2011

The selective surface oxidation of a transformation-induced-plasticity (TRIP) steel containing 1.6 wt.% Mn and 1.5 wt.% Si during annealing at $800^{\circ}C$ was investigated for its influence on the formation of an inhibition layer during hot-dip galvanizing. The selective oxidation of the alloying elements and the oxide morphology were significantly influenced by the annealing atmosphere. The pure $N_{2}$ atmosphere with a dew point $-40^{\circ}C$ promoted the selective oxidation of Mn as a crystalline $Mn_{2}SiO_{4}$ phase, whereas the $N_{2}$ + 10% $H_{2}$ atmosphere with the same dew point $-40^{\circ}C$ promoted the selective oxidation of Si as an amorphous Si-rich oxide phase. During hot-dip galvanizing, the $Mn_{2}SiO_{4}$ phase was reduced more readily by Al in the Zn bath than the Si-rich oxide phase. Consequently, the pure $N_{2}$ atmosphere resulted in a higher formation rate of $Fe_{2}Al_{5}$ particles at the Zn/steel interface and better galvanizability than the $N_{2}$ + 10% $H_{2}$ atmosphere.

• Journal of Convergence for Information Technology
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• v.11 no.7
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• pp.104-110
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• 2021

A novel selective oxidation process has been developed for low source/drain (S/D) series resistance of the fin channel metal oxide semiconductor field effect transistor (MOSFET). Using this technique, the selective oxidation fin-channel MOSFET (SoxFET) has the gate-all-around structure and gradually enhanced S/D extension regions. The SoxFET demonstrated over 70% reduction in S/D series resistance compared to the control device. Moreover, it was found that the SoxFET behaved better in performance, not only a higher drive current but also higher transconductances with suppressing subthreshold swing and drain induced barrier lowering (DIBL) characteristics, than the control device. The saturation current, threshold voltage, peak linear transconductance, peak saturation transconductance, subthreshold swing, and DIBL for the fabricated SoxFET are 305 ㎂/㎛, 0.33 V, 13.5 𝜇S, 76.4 𝜇S, 78 mV/dec, and 62 mV/V, respectively.