• 소성∙가공
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• 제22권8호
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• pp.486-491
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• 2013

A numerical investigation of the butting process for an AZ31B magnesium alloy tube at elevated temperatures was conducted to develop a double-butted magnesium alloy tube. As a result of the current study, it was found that the amount of doming of the tube end, prior ironing-extrusion to obtain high wall thickness reduction are important factors for the butting process of magnesium alloy tubes. There is also a limitation of the thickness profile of butted tube due to buckling of tube wall during the stripping stage.

• 한국분말재료학회지
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• 제17권2호
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• pp.142-147
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• 2010

The ultrafine titanium carbonitride ($TiC_xN_y$) particles below 100 nm in mean size, including various carbon and nitrogen contents (x=0.55~0.9, y=0.1~0.5), were successfully synthesized by new Mg-thermal reduction process. Nanostructured sub-stoichiometric titanium carbide ($TiC_x$) particles were initially produced by the magnesium reduction of gaseous $TiCl_4+x/2C_2Cl_4$ at $890^{\circ}C$ and post heat treatments in vacuum were performed for 2 hrs to remove residual magnesium and magnesium chloride mixed with $TiC_x$. Finally, well C/N-controled $TiC_xN_y$ phases were successfully produced by nitrification heat treatment under normal $N_2$ gas atmosphere at $1150^{\circ}C$ for 2 hrs. The values of purity, mean particle size and oxygen content of produced particles were about 99.3%, 100 nm and 0.2 wt.%, respectively.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
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• pp.221.2-221.2
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• 2011

In this study, we prepared the magnesium oxide decorated ordered mesoporous carbons processed by the reduction of magnesium oxide precursor on the CMK-3 surfaces in order to investigate the characterization and the effect on their carbon dioxide adsorption behaviors. The magnesium contents of the prepared samples were characterized using XPS. The textural properties of the prepared samples were investigated by $N_2$/77 K adsorption isotherms by BET equation. The carbon dioxide adsorption capacities of the prepared samples were investigated by the amounts of carbon dioxide adsorptions at 298 K and 1.0 atm. The results showed that the magnesium oxide on the CMK-3 surface enhanced interaction between carbon dioxide and adsorbents. Consequently, it was found that the magnesium oxide led to an increase in the carbon dioxide adsorption capacity of the CMK-3.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.546-547
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• 2007

Magnesium is widely used as a lightweight alloy for car engine components and case of cellular phone. Extraction technologies of magnesium are divided to fused salt electrolysis process and thermal reduction process. In this study, electrolysis magnesium is prepared by fused salt electrolysis process with magnesium chloride. We compared two kinds of mixed salt at 7V. As a result, 47% of current efficiency was obtained by electrolyzing KCl/NaCl/$MgCl_2$ mixed salt bath at $760^{\circ}C$, and purity of the prepared magnesium was over 98%. With this study, we can scale up fused salt electrolysis device and accumulate basic data which will be needed for designing an electrolysis cell.

• Asian-Australasian Journal of Animal Sciences
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• 제5권2호
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• pp.303-308
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• 1992

Three female sheep were daily administered a pyrophosphate analogue, disodium 1-hydroxyethylidene-1, 1-bisphosphonate (HEBP) at the level of 4 mg/kg body weight. HEBP largely suppressed bone resorption, which was indicated by the reduction in plasma free hydroxyproline concentration and in calcium mobilization rate during the intravenous infusion of disodium ethylenediaminetetraacetate (EDTA). Contrary to the suppression of bone resorption, plasma total-calcium, magnesium and phosphorus concentrations were not changed by HEBP administration. These results suggest that bone mineral crystals play a meaningless role on calcium, magnesium and phosphorus homeostasis in ruminants if they are fed adequate amounts of these minerals. Plasma magnesium and phosphorus concentrations were not significantly changed after feeding. However, plasma total-calcium was decreased after feeding in both periods and the reduction seemed to be remarkable in the HEBP-treated period. Infusion of EDTA more remarkably reduced plasma ionized calcium concentration in the HEBP-treated that in the untreated period and the recovery of ionized calcium was retarded by HEBP administration. These results suggest that calcium release from bone is necessary for maintenance of plasma calcium when animals rapidly lose calcium.

• 대한금속재료학회지
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• 제50권10호
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• pp.745-751
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• 2012

The Kroll process for magnesium reduction of titanium tetrachloride is used for mass production of titanium sponge. The present study was conducted in a lab scale reactor to develop a better understanding of the mechanism of titanium sponge formation in the Kroll reactor with respect to reaction degrees and the feeding rate of $TiCl_4$. The $MgCl_2$ produced during the initial stage of the reaction was not sunk into the molten magnesium, but covered the surface of the molten magnesium. As a result, subsequently fed $TiCl_4$ reacted with Mg exposed on the edge of molten $MgCl_2$ in the crucible. Therefore, titanium sponge grew toward the center of the crucible from the edge. The temperature of the molten magnesium increased remarkably with the increasing feeding rate of $TiCl_4$. Consequently, fed $TiCl_4$ reacted at the upper side of the crucible with evaporated Mg, and produced titanium on the upper surface of the crucible wall, which increased considerably with the feeding rate of $TiCl_4$.

• 대한금속재료학회지
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• 제49권6호
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• pp.454-461
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• 2011

In this study, the relationship between corrosion resistance and microstructural characteristics such as grain size reduction, preferred orientation, and homogenous distribution of elements and impurity by mechanical milling of magnesium powder was investigated. Mechanical milling of pure magnesium powder exhibited a complex path to grain refinement and growth together with preferred orientation reversal with milling time. It was also found that anisotropic formation of dislocation on the basal plane of magnesium was initially the dominant mechanism for grain size reduction. After 60 hrs of milling, grain coarsening was observed and interpreted as a result of the strain relaxation process through recrystallization. In spite of the finer grain size and strong (002) texture developed in the sample prepared by spark plasma sintering at $500^{\circ}C$ for 5 min after mechanical milling for 2hrs, the sample showed a higher corrosion rate. The results from this study will be helpful for better understanding of the controlling factor for corrosion resistance and behaviors of mechanical milled magnesium powders.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 추계학술대회 논문집
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• pp.220-226
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• 2005

To achieve the weight reduction of a vehicle, Magnesium alloys are widely used in automobile parts because of its lightweight characteristics. Magnesium alloys also have advantages in recycling, stiffness, NVH , heat protection. But Magnesium alloy parts are mainly manufactured by diecasting processes, their productivity was not so high compared to by sheet metal working. We are developing vehicle hood using magnesium sheets. In this study we designed magnesium alloy hood which have equivalent mechanical characteristics to steel hood. Using finite element method we decided thickness of magnesium sheets under some design requirements and we changed the shape of hood inner panel and hinge reinforcements. Outer and inner panel thickness was 1.3mm, 1.5mm respectively. Panel dentibility analysis was performed to conform the new magnesium design by nonlinear FEM package. Formability and hemming of Magnesium sheets are the subjects for further study because they have poor stretchability compared to steel sheets.

• Advances in concrete construction
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• 제8권1호
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• pp.39-45
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• 2019

Durability of strengthened reinforced concrete (RC) beams with CFRP sheets under wetting and drying cycles of magnesium sulfate attack is investigated in this research. Accordingly, 18 RC beams were designed and made where 10 of them were strengthened by CFRP sheets at their tension side. Magnesium sulfate attack and wetting and drying cycles with water and magnesium sulfate solution were considered as exposure conditions. Finally, flexural performance of the beams was measured before and after 5 months of exposure. Results indicated that the bending capacity of the strengthened RC beams was reduced about 10% after 5 months of immersion in the magnesium sulfate solution. Wetting and drying cycles of magnesium sulfate solution reduced the bending capacity of the strengthened RC beams about 7%. Also, flexural capacity reduction of the strengthened RC beams in water and under wetting and drying cycles of water was negligible.

• 소성∙가공
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• 제23권8호
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• pp.495-500
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• 2014

Magnesium alloys are currently expected to be widely used for weight reduction of cars and as high efficient materials in the automotive and electronics industries. Although the specific strength of magnesium is excellent, it cannot be easily formed at room temperature due to its HCP structure. However in order to improve the formability of magnesium, it is necessary to investigate its formability in the warm temperature range. In the current study, the aim was to add to the magnesium property database so that the mass production of a magnesium car body can be accomplished. Warm tensile tests were conducted and the forming limit diagram was determined to confirm formability characteristics of magnesium AZ31B alloy sheet. In addition the bending formability and the magnesium damping capacity were evaluated for AZ31B and compared to SPRC440E which is a sheet steel used for car bodies.