• Bulletin of the Korean Chemical Society
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• v.21 no.12
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• pp.1233-1238
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• 2000

$Mo/{\gamma}-Al_2O_3catalysts$ modified with Fe, Co, and Ni were prepared by impregnation method and catalytic activity for water gas shift reaction was examined. The optimum amount of Mo loaded for the reaction was 10 wt% $MoO_3$ to ${\gamma}-Al_2O_3.$ The catalytic activity of $MoO_3/{\gamma}-Al_2O_3was$ increased by modifying with Fe, Co, and Ni in the order of Co${\thickapprox}$ Ni > Fe. The optimum amounts of Co and Ni added were 3 wt% based on CoO and NiO to 10 wt% $MoO_3/{\gamma}-Al_2O_3$, restectively. The TPR (temperature-programmed reduction) analysis revealed that the addition of Co and Ni enganced the reducibility of the catalysts. The results of both catalytic activity and TPR experiments strongly suggest that the redox property of the catalyst is an important factor in water gas shift reaction on the sulfided Mo catalysts, which could be an evidence of oxy-sulfide redox mechanism.

• Korean Journal of Materials Research
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• v.11 no.11
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• pp.986-990
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• 2001

An optimum route to fabricate the $A1_2O_3/Fe-Ni$ alloy nanocomposites with sound microstructure and enhanced mechanical properties as well as magnetism was investigated. To prepare homogeneous nanocomposite powders of Fe-Ni alloy and $Al_2O_3$, the solution-chemistry routes using $Al_2O_3 \; Ni(NO_3)_2{\cdot}6H_2O$ and $Fe(NO_3)_3{\cdot}9H_2O$ powders were applied. Microstructural observation of the powder mixture revealed that the Fe-Ni alloy particles of about 20 nm in size were homogeneously surrounded $A1_2O_3$, forming nanocomposite powder. The hot-pressed composite showed improved fracture toughness and magnetic response. These results suggest that the synergy materials with an improved mechanical properties and excellent functionality can be fabricated by controlled powder preparation and consolidation processing.

• Journal of Powder Materials
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• v.16 no.2
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• pp.91-97
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• 2009

Nanopowders of $Co_3O_4$ and FeAl were fabricated by high energy ball milling. Dense 4.25 $Co_{0.53}Fe_{0.47}-Al_2O_3$ composite was simultaneously synthesized and consolidated by high frequency induction heated combustion method within 2 min from mechanically activated powders. Consolidation was accomplished under the combined effects of a induced current and mechanical pressure of 80 MPa.

• Korean Journal of Metals and Materials
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• v.47 no.6
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• pp.344-348
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• 2009

Dense $4.25Co_{0.53}Fe_{0.47}-Al_{2}O_{3}$ composite was simultaneously synthesized and consolidated by pulsed current activated combustion method within 2 min from mechanically activated powders. Consolidation was accomplished under the combined effects of a pulsed current and mechanical pressure. Dense $4.25Co_{0.53}Fe_{0.47}-Al_{2}O_{3}$ with relative density of up to 96% was produced under simultaneous application of 80 MPa pressure and the pulsed current. Fracture toughness and hardness of the composite are $6MPa{\cdot}m^{1/2}$ and $570kg/mm^{2}$ respectively.

• Korean Journal of Metals and Materials
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• v.47 no.11
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• pp.754-758
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• 2009

Dense $5Cu_{0.6}Fe_{0.4}-Al_{2}O_{3}$ composite was consolidated from mechanically synthesized powders by high frequency induction heating method within 2 min. Consolidation was accomplished under the combined effects of a induced current and mechanical pressure. Dense $5Cu_{0.6}Fe_{0.4}-Al_{2}O_{3}$ with relative density of up to 95% was produced under simultaneous application of a 80 MPa pressure and the pulsed current. Fracture toughness and hardness of the composite are $7.6MPa{\cdot}m^{1/2}$ and $844kg/mm^{2}$ respectively.

• Korean Journal of Materials Research
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• v.1 no.4
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• pp.198-205
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• 1991

Sintered thermistor body was fabricated by solid reaction method using $Fe_2O_3, \;Al_2O_3, \;TiO_2$ and Si powder. Surface matrix of sintered body was investigated by SEM and $\beta$-constant was obtained from measurement of resistance variation in liquid bath. The values of thermistor constant $\beta$ of samples in the temperature range $-50~+50^{\circ}C$ were distributed from 927 to 4005k. This thermistor body can be used as temperature sensor for radiosonde.

• Journal of the Korean Ceramic Society
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• v.31 no.3
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• pp.235-240
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• 1994

The electric and magnetic properties of Mg1.9-2xMn0.05Fe4xO4+${\gamma}$+2wt% Al2O3, and its microstructure have been investigated as a function of ferrite composition (x=0.45, 0.5, 0.55). The microstructure turned out to be independent on the ferrite composition. The resistivity was decreased with increasing Fe contents, whereas the Curie temperature decreased. Saturation magnetization was varied from 1741 to 2022 G with composition, and squareness ratio (SR), coercive force (BHc) were decreased and increased with increasing Fe contents respectively, so the sample which SR and BHc were 0.97 Oe and 1.49 Oe can be attainable at x=0.45.

• Korean Journal of Metals and Materials
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• v.49 no.3
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• pp.231-236
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• 2011

Nanopowder of $Fe_2O_3$, Al, Cr and Si was fabricated by high energy ball milling. A dense nanostuctured $A_2O_3$ and $6.06Fe_{0.33}Cr_{0.16}Al_{0.23}Si_{0.29}$ composite was simultaneously synthesized and consolidated using high frequency induction heated sintering method within 1 minute from mechanically activated powders of $Fe_2O_3$, Al, Cr and Si. The grain sizes of $Al_2O_3$ and $Fe_{0.33}Cr_{0.16}Al_{0.23}Si_{0.29}$ in composite are 80 and 18 nm, respectively.

• Journal of Sensor Science and Technology
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• v.11 no.1
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• pp.18-27
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• 2002

$LaFeO_3$-based thick films with 2wt.%, 5wt.% and 10wt.% $Al_2O_3$ additives were fabricated by screen printing method on $Al_2O_3$ substrates. Structural, electrical and ammonia gas sensing characteristics of the thick films with different heat treatment temperatures were examined. From XRD results, the compound of $LaFeO_3$ and $Al_2O_3$ was not found until the heat treatment at $1200^{\circ}C$. SEM microphotograph showed similar grain growth despite the amount of $Al_2O_3$ additives with the heat treatment. Thick films with high activation energy and low resistance in the electrical properties showed high sensitivity for gases. Thick films with 2wt % $Al_2O_3$ additives heat-treated at $1200^{\circ}C$ showed the sensitivities of 210% for 100 ppm $NH_3$ gas at the working temperature of $350^{\circ}C$. The thick films showed food selectivity to $NH_3$ gas.

• Applied Chemistry for Engineering
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• v.20 no.5
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• pp.522-526
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• 2009

The catalytic oxidation of 1,2-dichloribenzene (1,2-DCB) and simultaneous catalytic reduction of nitrogen oxides over the single catalyst has been investigated over various metals (Ru, Mn, Co and Fe) supported on $Al_2O_3$ and $CeO_{2}$. The activity of the different catalysts for catalytic oxidation of 1,2-dichloribenzene depended on the used metal, Ru/Co/$Al_2O_3$, Mn-Fe/CeO2 and Cr/$Al_2O_3$ (commercial catalysts) being the most actives ones. In the catalytic oxidation of chlorobenzene (CB), Ru/Co/$Al_2O_3$ is better than Pt-Pd/$Al_2O_3$, which is the well-known catalyst good for VOC oxidation. Furthermore, it has a good durability on the deactivation by $Cl_2$ and sulfur. For nitrogen oxides (NOx) removal, NOx conversion was 70% at $260^{\circ}C$.