• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2005년도 제24회 춘계학술대회논문집
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• pp.106-111
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• 2005

Failure mechanisms were investigated for the two layer thermal barrier coatings consisting of NiCrAlY bond coat and $ZrO_2-8wt.\% Y_{2}O_3$ ceramic coating during cyclic oxidation. $Al_{2}O_3$ developed at the ceramic coating/bond coat interface first, followed by the Cr/Ni rich oxides such as $NiCr_{2}O_4 and Ni(Al,Cr)_{2}O_4$ during cyclic oxidation It was observed that the spalling of ceramic coatings took place primarily within the NiCrAlY bond coat oxidation products or at the interface between the bond coat oxidation products and zirconia based ceramic coating or the bond coat. It was also observed that the fracture within these oxidation products occurred with the formation of $Ni(Cr,Al)_{2}O_4$ spinel or Cr/Ni rich oxides. It was therefore concluded that the formation of these oxides was a life-limiting event for the thermal barrier coatings.

• The Korean Journal of Ceramics
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• 제4권4호
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• pp.340-344
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• 1998

Failure mechanisms were investigated for the two layer thermal barrier coatings consisting of NiCrAlY bond coat and $ZrO_2$-8wt.% $Y_2O_3$ ceramic coating during cyclic oxidation. $Al_2O_3$ developed at the ceramic coating/bond coat interface first, followed by the Cr/Ni rich oxides such as $NiCr_2O_4$ and $Ni(Al, Cr)_2O_4$ during cyclic oxidation. It was observed that the spalling of ceramic coatings took place primarily within the NiCrAlY bond coat oxidation products or at the interface between the bond coat oxidation products and zirconia based ceramic coating or the bond coat. It was also observed that the fracture within these oxidation products occurred with the formation of $Ni(Cr, Al)_2O_4$ spinel or Cr/Ni rich oxides. It was therefore concluded that the formation of these oxides was a life-limiting event for the thermal barrier coatings.

• Bulletin of the Korean Chemical Society
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• 제34권7호
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• pp.2073-2080
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• 2013

In this study the effects of adding alkaline-earth (IIA) metal oxides to NiZr-loaded Zeolite Y catalysts were investigated on hydrogen rich production by ethanol steam reforming (ESR). Four kinds of alkaline-earth metal (Mg, Ca, Sr, or Ba) oxides of 3.0% by weight were loaded between the $Ni_6Zr_4O_{14}$ main catalytic species and the microporous Zeolite Y support. The characterizations of these catalysts were examined by XRD, TEM, $H_2$-TPR, $NH_3$-TPD, and XPS. Catalytic performances during ESR were found to depend on the basicity of the added alkaline-earth metal oxides and $H_2$ production and ethanol conversion were maximized to 82% and 98% respectively in 27($Ni_6Zr_4O_{14}$)3MgO/70Zeolite Y catalyst at $600^{\circ}C$. Many carbon deposits and carbon nano fibers were seen on the surface of $30Ni_6Zr_4O_{14}$/70Zeolite Y catalyst but lesser amounts were observed on alkaline-earth metal oxide-loaded 27($Ni_6Zr_4O_{14}$)3MO/70Zeolite Y catalysts in TEM photos after ESR. This study demonstrates that hydrogen yields from ESR are closely related to the acidities of catalysts and that alkaline-earth metal oxides reduce the acidities of 27($Ni_6Zr_4O_{14}$)3MO/70Zeolite Y catalysts and promote hydrogen evolution by preventing progression to hydrocarbons.

• 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.

• Corrosion Science and Technology
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• 제21권6호
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• pp.466-475
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• 2022

Surface oxides and intergranular (IG) oxidation phenomena in Alloy 600 depending on hydrogen concentration were characterized to obtain clear insight into the primary water stress corrosion cracking (PWSCC) behavior upon exposure to pressurized water reactor primary water. When hydrogen concentration was between 5 and 30 cm³ H₂/kg H₂O, NiFe₂O₄ and NiO type oxides were found on the surface. NiO type oxides were found inside the oxidized grain boundary when hydrogen concentration was 5 cm³ H₂/kg H₂O. However, only NiFe₂O₄ spinel on the surface and Ni enrichment were observed when hydrogen concentration was 30 cm³ H₂/kg H₂O. These results indicate that the oxidation/reduction reaction of Ni in Alloy 600 depending on hydrogen concentration can considerably affect surface oxidation behavior. It appears that the formation of NiO type oxides in a Ni oxidation state and Ni enrichment in a Ni reduction (or metallic) state are common in primary water. It is believed that the above different oxidation/reduction reactions of Ni in Alloy 600 depending on hydrogen concentration can also significantly affect the resistance to PWSCC of Alloy 600.

• Korean Chemical Engineering Research
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• 제55권3호
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• pp.379-384
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• 2017

LiCl 용융염에서 희토류 산화물의환원율을 높이기 위해 NiO와 혼합하여 전해환원을실시하였다. Cyclic voltammetry (CV) 실험을 통해 LiCl 용융염 내에서 혼합산화물의 전기화학적 환원거동을 조사하였다. 혼합산화물로 제작된 환원전극과 그라파이트 산화전극 사이에 일정한 작동전압을 인가하여 이론전하량 대비 다양한 전하량을 공급한 후 중간생성물의 결정구조를 XRD를 이용하여 분석하였다. NiO 산화물을 첨가함으로써 전기전도성이 좋은 Ni 금속 주위로 희토류 산화물이 환원되어 RE-Ni 합금형태의 금속으로 완전히 전환되었으며, 합금을 형성하는 반응 메커니즘을 제시하였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.663-663
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• 2013

We prepared Cu oxides, and Ni and Pd-TiO2@SiO2 core-shellnanostructures, and tested their CO oxidation performances by temperature-programmed mass spectrometry. We found the starting temperatures of CO oxidation are around $200^{\circ}C$ and $300^{\circ}C$ for Ni and Pd-TiO2@SiO2 nanostructures, respectively. Cu oxides are cubes with 50~200 nm with, prepared with different concentrations of NaOH and ascorbic acid. For the core-shell structures, we prepared 100 nm SiO2 spheres, first coated the surface with TiO2 precursor, and then coated with Ni and Pd. Their characteristics are further examined by scanning electron microscopy, optical microscope, FT-IR, and UV-Vis absorption spectroscopy.

• Korean Chemical Engineering Research
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• 제56권2호
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• pp.269-274
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• 2018

All the $Ni-Co-Ce-ZrO_2$ mixed oxides are prepared by co-precipitations methods. Methanation of CO and $H_2$ reaction is screened tested over different fractions of cerium (2, 4, 7 and 12 wt.%) over $Ni-Co/ZrO_2$ bimetallic catalysts are investigated. The mixed oxides are characterized by XRD, CO-Chemisorption, TGA and screened methanation of CO and $H_2$ at $360^{\circ}C$ for 3000 min on stream at typical ratio $CO:H_2=1:1$. In $Ni-Co/CeZrO_2$ series 2 wt.% Ce loading catalyst shows most promising catalyst for $CH_4$ selectivity than $CO_2$, which directs more stability with less coke formation. The high activity is attributed to the better bimetallic synergy and the well-developed crystalline phases of NiO, $ZrO_2$ and $Ce-ZrO_2$. Other bimetallic mixed oxides NCoZ, $NCoC^{4-12}Z$ has faster deactivation with low methanation activity. Finally, 2 wt.% Ce loading catalyst was found to be optimal coke resistant catalyst.

• 한국재료학회지
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• 제12권3호
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• pp.220-224
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• 2002

The oxide scales formed on $Ni_3Al$-7.8%Cr-1.3%Zr-0.8%Mo-0.025%B after oxidation at 900, 1000 and 110$0^{\circ}C$ in air were studied using XRD, SEM, EPMA and TEM. The oxide scales consisted primarily of $NiO,\; NiAl_2O_4,\;{\alpha}-Al_2O_3,\; monoclinic-ZrO_2,\; and \;tetragonal-ZrO_2$. The outer layer of the oxide scale was rich in Ni-oxides, whereas the internal oxide stringers were rich in Al-oxides and $ZrO_2$. Within the above oxide scales, Cr and Mo tended to exist as dissolved ions.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2003년도 international symposium on advanced powder metallurgy
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• pp.65-66
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• 2003

1. The oxidation resistance of $Y_{2}O_{3}$ containing Ni-base alloy is superior to that of the alloy without $Y_{2}O_{3}$. 2. The appearance of oxides of Ni-20Cr-20Fe-5Nb-$1Y_{2}O_{3}$ alloy is similar to that of oxides in commercial PM1000 and MA754 alloy. 3. The oxides in ODS alloy are grown mainly at particle boundaries.