• Advances in materials Research
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• v.1 no.2
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• pp.147-160
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• 2012

In the present study, diffusion bonding was carried out between AZ31B magnesium and AA2024 aluminium in the temperature range of $405^{\circ}C$ to $475^{\circ}C$ for 15 min to 85 min and 5MPa to 20 MPa uniaxial loads was applied. Interface quality of the joints was assessed by microhardness and shear testing. Also, the bonding interfaces were analyzed by means of optical microscopy, scanning electron microscopy, energy dispersive spectrometer and XRD. The maximum bonding and shear strength was obtained at $440^{\circ}C$, 12 MPa and 70 min. The maximum hardness values were obtained from the area next to the interface in magnesium side of the joint. The hardness values were found to decrease with increasing distance from the interface in magnesium side while it remained constant in aluminium side. It was seen that the diffusion transition zone near the interface consists of various phases of $MgAl_2O_4$, $Mg_2SiO_4$ and $Al_2SiO_5$.

• Journal of the Korean Ceramic Society
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• v.23 no.6
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• pp.71-75
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• 1986

The forming reaction processes of magnesium aluminate spinel by a thermal decomposition of sulfate hydrate were studied with DTA, TG. SEM and X-ray powder diffraction methods. The hydrous salt composed of the mixture of the two compounds of $MgSO_4$ $6H_2O$ and ${AL_2}({SO_4})_17H_2O_3$ in which both sulfates were crystalline. On heating the hydrous slat the crystalline magnesium and aluminum sulfate anhydride to amorphous alumina magnesium sulfate anhydride decomposed to amorphous magnesia and these amorphous oxides reacted completely each other to form a spinel at $1000^{\circ}C$ The apparent activation energy of forming reaction of spinel was 36.5 kcal/mole($900^{\circ}C$~$1000^{\circ}C$) The crystallite size of spinel obtained at $1000^{\circ}C$ after 1 h was 380$\AA$.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.3 no.1
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• pp.52-58
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• 2004

The material used is a commercial magnesium based alloy AZ31(Mg-3Al-1Zn)sheet with a thickness of 1.0mm. Uniaxial tension tests at warm temperature were carried out to investigate the material characteristics of K, m, and n. A warm drawing process with a local heating and cooling technique was developed to improve formability in this study with results of uniaxial tension tests because it is very difficult for Mg alloy to deform at room temperature by the conventional method. The die and blank holder were heated up, while the punch was water-cooled during deformation. FE simulations considering heat transfer were executed with Mg alloy to investigate the Improvement of deep drawability. For the assessment of improvement those were compare with the results of no considering heat transfer and room temperature.

• Journal of the East Asian Society of Dietary Life
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• v.10 no.6
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• pp.495-506
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• 2000

The purpose of this study was to assess the nutritional status of iron and magnesium and the effect of von supplementation during 8 weeks(from 20 to 28 weeks of gestation) on serum iron and magnesium status of 31 pregnant women in Kyunsin area. The age, weight, and height of the subjects before pregnancy were investigated by questionnaires. At 20 and 28 weeks of gestation, data for food and nutrient intake were obtained by questionnaires and serum sample was obtained. According to the frequency of iron supplementation, subjects were divided into two groups(4$\geq$/wk) The mean iron supplementation of 5 $\geq$/wk group(63.mg/day) was significantly higher than 4$_2$ intakes were much less than the Korean RDA. Especially, calcium, iron and magnesium intakes showed half the levels compared with Korean RDA. At 28 weeks of gestation the serum total protein(p<0.001), albumin(p<0.01) and globulin(p<0.001) were significantly decreased. Total iron binding capacity(TIBC) was significantly increased(P<0.001), but serum ferritin(p<0.01) and magnesium(p<0.01) concentrations were significantly decreased. However, even 28 weeks of gestation 5$\geq$/wk group showed higher serum iron and ferritin concentration and lower TIBC than 4$\geq$/wk group. Therefore, iron supplementation should be conducted with concerning the mineral balance like magnesium.

• Korean Chemical Engineering Research
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• v.50 no.6
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• pp.939-944
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• 2012

The electrochemical behavior of magnesium ions was examined by cyclic voltammetry in a molten $MgCl_2-CaCl_2$-NaCl salt. The reduction potential of magnesium ions was measured and those values were estimated with the variation of the concentration of $MgCl_2$ and the temperature of molten salts. The diffusion coefficient of the $Mg^{2+}$ ions has been determined at 660, 680, 700, 720 and $740^{\circ}C$. The values were $8.79{\times}10^{-6}$, $9.56{\times}10^{-6}$, $1.17{\times}10^{-5}$, $1.4{\times}10^{-5}$ and $1.77{\times}10^{-5}\;cm^2\;s^{-1}$. The activation energy for the diffusion processes of $Mg^{2+}$ ions was found to be $70.28\;kJ\;mol^{-1}$ by using the Arrhenius equation.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.10
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• pp.77-83
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• 2002

Magnesium alloys casting are gaining increased acceptance in the automotive and electronic industeries and die casting is the most efficient method of manufacturing such mass produced parts. This study has been investigated the microstructures and mechanical properties of Mg-9Al-lZn alloy fabricated by die casting process for development of air bag case. The microstructure of die casted specimen were composed of pro-eutectic magnesium solid solution and $\beta$(Mg17Al12) precipitates. The tensile strength of as-fabricated Mg-9Al-lZn alloy revealed 231.4MPa. It was found that Mg-9Al-lZn alloy have good corrosion resistance in electrochemical polarization test.

• Journal of Korea Foundry Society
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• v.30 no.6
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• pp.217-223
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• 2010

Foamed metal has become an attractive material, which has unique physical, thermal, acoustic, damping and mechanical properties, because large amount of pores are distributed in the metal matrix. Therefore, metal foam can be used for the light weight application in automotive, locomotive, aerospace fields. Aluminum foams have been developed successfully and will be employed in the next generation of energy absorption boxes. Magnesium alloys are most eligible candidate to substitute aluminum alloy, especially for lower density and higher damping properties in wide industrial fields. Magnesium alloy foams are expected to be particularly advantageous due to two thirds the density of aluminum. However, foaming magnesium have been weakness of high activity, difficult processing and very dangerous. In order to upgrade this problem, AM50 magnesium alloy which has better characteristic is safe to use through foaming time and alloying element in this study.

• Journal of the Korean institute of surface engineering
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• v.49 no.2
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• pp.202-210
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• 2016

This study was intended to investigate the effect of the amount of magnesium addition and heat treatment in the Al-Mg coating film in order to improve corrosion resistance of aluminum coating. Al-Mg alloy films were deposited on cold rolled steel by physical vapor deposition sputtering method. Heat treatment was fulfilled in an nitrogen atmosphere at the temperature of $400^{\circ}C$ for 10 min. The morphology was observed by SEM, component and phase of the deposited films were investigated by using GDLS and XRD, respectively. The corrosion behaviors of Al-Mg films were estimated by exposing salt spray test at 5 wt.% NaCl solution and measuring polarization curves in deaerated 3 wt.% NaCl solution. With the increase of magnesium content, the morphology of the deposited Al-Mg films changed from columnar to featureless structure and particle size was became fine. The x-ray diffraction data for deposited Al-Mg films showed only pure Al peaks. However, Al-Mg alloy peaks such as $Al_3Mg_2$ and $Al_{12}Mg_{17}$ were formed after heat treatment. All the sputtered Al-Mg films obviously showed good corrosion resistance compared with aluminum and zinc films. And corrosion resistance of Al-Mg film was increased after heat treatment.

• Korean Journal of Veterinary Research
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• v.25 no.1
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• pp.41-48
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• 1985

In the present studies, the effects of dietary high-potassium and high-urea on the metabolism of magnesium, calcium and potassium were checked as an aid to clarify the pathogenesis of hypomagnesaemia(so-called grass tetany) in ruminant. A total of 5 Korean native female goats kept in metabolic cage were received high-potassium(Mg: 0.25%, Ca: 0.94%, K: 5.41%), high-urea(Mg: 0.25%, Ca: 0.94%, K: 0.72%) or control(Mg: 0.25%, Ca: 0.94, K: 0.72%) ration for 15 or 21 days. Daily intakes, fecal and urinary excretions and serum concentrations of magnesium, calcium and potassium were measured with an atomic absorption spectrophotometer. The results obtained were summarized as follows: In high-potassium group, absorption, urinary excretion and serum concentration of magnesium were significantly (p<0.01, p<0.01 and p<0.05 respectively) decreased compared with the control group. On the other hand, the body retention was significantly (p<0.01) increased. However, no clinical symptom of hypomagnesaemic tetany was observable throughout the experimental period. No significant effects on the metabolism and seurm content of calcium were detected in the high-potassium group. In the high-potassium group, significant increase in absorption (p<0.01), urinary excretion (p<0.05) and body retention (p<0.01) of potassium were recognized. However, no significant difference in the concentration of serum was observable between the two groups. In high-urea group, no significant difference in the metabolism of magnesium and potassium or in the serum content were recognized compared with the control group. In high-urea group, tthe absorption, urinary excretion, body retention and serum content of calcium were decreased compared with the control group.

• Corrosion Science and Technology
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• v.18 no.6
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• pp.243-252
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• 2019

The pitting corrosion and inhibition studies of AZ31B magnesium alloy were investigated in the alkaline solution (pH12) with chloride and inhibitors. The corrosion behavior of passive film with/without Cl^- in the alkaline electrolyte were conducted by polarization curve and immersion tests in the presence of various additives (inhibitors) to clarify the inhibition efficiency of pitting corrosion at higher potential region. Critical concentration of pitting corrosion for Mg alloy was evaluated with 0.005 M NaCl in 0.01 M NaOH on the anodic polarization behavior. Critical pitting of AZ31B Mg alloy in 0.01 M NaOH is a function of chlorides; E_pit = - 1.36 - 0.2 log [Cl^-]. When the Sodium Benzoate (SB) was only used as an inhibitor, a few metastable pits developed on the Mg surface by an immersion test despite no pitting corrosion on the polarization curve meaning that adsorption of SB on the surface is insufficient protection from pitting corrosion in the presence of chloride. The role of SB and Sodium Dodecylbenzenesulfonate (SDBS) inhibitors for the Mg alloy surface in the presence of chloride was suppressed from pitting corrosion to co-adsorb on the Mg alloy surface with strong formation of passive film preventing pitting corrosion.