• Title, Summary, Keyword: Magnesium

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A Study of forming limit on rotational incremental forming of magnesium alloy sheet (회전 인크리멘탈 성형을 이용한 마그네슘 합금 판재의 성형한계 연구)

  • Park, J.K.;Bae, M.K.;You, B.S.;Kim, Y.S.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.456-461
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    • 2008
  • Being a lightweight material, magnesium is increasingly employed in automotive parts. However, because of its hexagonal closed-packed (HCP) crystal structure, in which only the basal plane can move, the magnesium alloy sheets show low ductility and formability at room temperature. Thus the press forming of magnesium alloy sheets has been performed at elevated temperature within range of $200^{\circ}C{\sim}250^{\circ}C$. However, we confirmed that using rotational incremental forming magnesium alloy sheets were formed without any heating at previous study. In this study, at the forming of square cup using rotational incremental sheet forming, the strain distributions were obtained and it was compared with forming limit curve at neck (FLCN). Also, forming limit curves at fracture (FLCF) of magnesium alloy sheets were obtained at elevated temperature and it was compared with the strain distribution of square cup of magnesium alloy sheet. In this study, we confirmed that conventional forming limit curves can not predict rotational incremental forming.

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Evaluation of Mechanical Properties for AZ31 Magnesium Alloy(1) (AZ31 마그네슘 합금 판재의 기계적 특성 평가(1))

  • Won S.Y.;Oh S.K.;Osakada Kozo;Park J.K.;Kim Y.S.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.53-56
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    • 2004
  • The mechanical properties and optical micrographs are studied for rolled magnesium alloy sheet with hexagonal close packed structure(HCP) at room and elevated temperatures. Tensile properties such as tensile strength, elongation, R-value and n-value are also measured for AZ31 magnesium alloy. Magnesium with strong texture of basal plane parallel to the rolling direction usually has high R-value and plastic anisotropy at room temperature. As temperature increases, the R-value for AZ31 magnesium sheet decreases. In addition, the AZ31 sheet becomes isotropy and recrystallization above $200^{\circ}C$. Formability of magnesium alloy sheets remarkably poor at room temperature is improved by increasing temperature. Sheet forming of magnesium alloy is practically possible only at high temperature range where plastic anisotropy disappears.

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Shrinkage Strain Property of the Magnesium Oxide Matrix According to Magnesium Chloride Addition Ratio (염화마그네슘 첨가율에 따른 산화마그네슘 경화체의 길이변화 특성)

  • Jung, Byeong-Yeol;Lee, Sang-Soo;Song, Ha-Young
    • Proceedings of the Korean Institute of Building Construction Conference
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    • pp.150-151
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    • 2013
  • Recently, the internal space organization of the building changes to the frame construction and flat slab construction in the wall type structure. And the use of light weight panel changing the internal joint use easily is increased. Therefore, in this research, the length change characteristic that the magnesium chloride addition rate reaches to the magnesium curing body tries to be studied. It could confirm according to the length change specific result that the magnesium chloride amount of addition reaches to the magnesium oxide curing body to expand. And the thing described below was the large-scale expansion the magnesium oxide addition rate 60%. And it showed up as 50, 40, 30, 20, and order of 10s (%). It could look at to form the hydrate of the SEM picture result needle-shaped of the Hardened.

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Biodegradation of Secondary Phase Particles in Magnesium Alloys: A Critical Review

  • Kannan, M. Bobby
    • Corrosion Science and Technology
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    • v.15 no.2
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    • pp.54-57
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    • 2016
  • Magnesium alloys have been extensively studied in recent years for potential biodegradable implant applications. A great deal of work has been done on the evaluation of the corrosion behaviour of magnesium alloys under in vitro and in vivo conditions. However, magnesium alloys, in general, contain secondary phase particles distributed in the matrix and/or along the grain boundaries. Owing to their difference in chemistry in comparison with magnesium matrix, these particles may exhibit different corrosion behaviour. It is essential to understand the corrosion behaviour of secondary phase particles in magnesium alloys in physiological conditions for implant applications. This paper critically reviews the biodegradation behaviour of secondary phase particles in magnesium alloys.

The Role of Magnesium and Calcium in Eggshell Formation in Tsaiya Ducks and Leghorn Hens

  • Shen, T.F.;Chen, W.L.
    • Asian-Australasian Journal of Animal Sciences
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    • v.16 no.2
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    • pp.290-296
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    • 2003
  • Tsaiya ducks and Leghorn hens are the two major laying birds raised in Taiwan. They are all excellent egg layers. Tsaiya ducks are small in body size (1.3 kg) with bigger egg weight (65 g) and stronger eggshell breaking strength than eggs from hens. The eggshell consists mainly of calcium carbonate, hence calcium plays an important role in the eggshell formation. Magnesium is also present in eggshell in small amounts, which may have effect on maintaining eggshell quality. In comparison studies, it was shown that the duck eggshells contained higher calcium and lower magnesium content than chicken eggshells. The eggshell magnesium content was not affected by the dietary magnesium levels (690-2380 ppm) in ducks, but in hens, it increased linearly with dietary magnesium levels. The palisade layer ($5000{\times}$) of the eggshell was found to have a compact form for ducks while there are many hallow vesicles in chicken eggshells. The eggshell magnesium deposition model is different for ducks and hens with ducks having a one-peak and hens having a two-peak model. The calcium deposition model is similar for both birds. Both the carbonic anhydrase specific activity and total activity in the shell gland mucosa of ducks are higher than those in hens. Ducks retain higher magnesium and lower calcium in the shell gland mucosa and secret less magnesium and more calcium into the shell gland lumen for eggshell deposition. The ATPase specific activity is maintained fairly constant during the eggshell forming stage, indicating continuous calcium transport into the shell gland lumen for eggshell formation. The magnesium content in duck eggshells is much lower than that in hens indicating that the magnesium content in the eggshell may have an effect on eggshell quality.

Precipitation of Magnesium Sulfate from Concentrated Magnesium Solution for Recovery of Magnesium in Seawater (해수 중 마그네슘 회수를 위한 마그네슘 농축액으로부터 황산마그네슘의 석출)

  • Cho, Taeyeon;Kim, Myoung-Jin
    • Resources Recycling
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    • v.25 no.4
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    • pp.32-41
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    • 2016
  • The precipitation test, which is the last step of magnesium recovery process consisting of three processes (pre-precipitation, selective dissolution of magnesium, precipitation) is performed to obtain magnesium sulfate powder from seawater. In the study, we succeed in precipitating the magnesium sulfate by adding acetone into the solution of magnesium over 4 times concentrated from seawater. The yield efficiency of magnesium sulfate increases with increasing pH and the ratio of added acetone. More than 99% of magnesium is obtained as magnesium sulfate hydrate ($MgSO_4{\cdot}6H_2O$) under the following conditions; pH 1.0 ~ 1.5, and the ratio of solution and acetone 1 : 1.5 (v:v). The acetone used in the precipitation process is recovered by the fractional distillation.

Effect of Serum magnesium Concentration on Postoperative Arrhythmias after Open Heart Surgery (혈중 마그네슘 농도가 개심술후 부정맥의 발생에 미치는 영향)

  • Kang, Chang-Hyun;Huh, Jae-Hak;Kim, Ki-Bong;Kim, Won-Gon;Ahn, Hyuk;Kim, Joo-Hyun;Kim, Chong-Whan
    • Journal of Chest Surgery
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    • v.33 no.1
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    • pp.51-59
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    • 2000
  • Background: Magnesium is one of the important intracellular cations. Hypomagnesemia is common after an open heart surgeryand may affect the development of posoperative arrhythmias. The aims of this study were to identify 1) the severity of the hypomagnesemia 2) the adequate dose of the magnesium replacement and 3) the effect of magnesium replacement on the postoperative arrhythmias. Material and Method: The serum magnesium level was measured in 20 patients in whom magnesium was replaced postopertively(6gm at the operative day 4gm at the 1st postoperative day and 2gm at the 2nd postoperative day) and compared with that of the 13 patients in whom magnesium was not replaced postopertively The serum magnesium level was normalized after magnesium replacement. We analyzed the development of arrhythmias in the patients groups who did not receive magnesium and were operated on between Oct. 1994 and Oct. 1995(Group I; n=206) and who received the magnesium postoperatively and were operated on between Nov. 1995 and Aug. 1996(Group II; n=133) Result: There were no differences in the preoperative risk factors and the rate of postoperative supraventricular or ventricular tachyarrhythmia occur-rences irrespectivel of the magnesium replacement. Magnesium replacement could prevent the aggrevation of the occurrence of postoperative arrhythmias in high risk groups of ventricular tachyarrhytnmia in old age but magnesium could not prevent postoperative arrhythmia in other high risk groups. Conclusion: The magnesium replacement after open heart surgery could prevent the development of ventricular tachyarrhythmias especially in old age groups but could not prevent atrial tachyarrhthmias.

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A Study on Static-Implicit Forming Analysis of the Magnesium Alloy Sheet (마그네슘 합금 판재의 정적-내연적 성형해석에 관한 연구)

  • Son, Young-Ki;Jung, Dong-Won
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.7 no.4
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    • pp.44-49
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    • 2008
  • The characteristic of magnesium alloy is the most light in utility metal, the effect of electromagnetic wave interception, excellent specific strength and absorptiveness of vibration. Although magnesium alloy with above characteristic is a subject matter which is suitable in world-wide tendency of electrical component frame, sheet magnesium alloy is difficult to process. Therefore, forming analysis of sheet magnesium alloy and applying warm-working to process are indispensable. Among Finite element method, the static implicit finite element method is applied effectively to analyze sheet magnesium alloy stamping process, which include the forming stage. In this study, it was focused on the crack, wrinkling and spring back on sheet magnesium alloy stamping by the static implicit analysis. According to this study, the result of simulation will give engineers good information to access the forming technique on sheet magnesium alloy. And its application is being increased especially in the production of electrical component frame for the cost reduction, saving of defective ratio, and improvement of Productivity.

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Effect of Magnesium Sulfate on Sisomicin Fermentation (Sisomicin 발효에 대한 Magnesium Sulfate의 영향)

  • 한상헌;신철수
    • Microbiology and Biotechnology Letters
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    • v.20 no.2
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    • pp.213-218
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    • 1992
  • Fermentation patterns were changed by adding magnesium sulfate to the fermentation broth and its effect on enhancement of sisomicin production was investigated. When cell growth was expressed by DNA content, trophophase and idiophase were separated, but not by dry cell weight. On the other hand, addition of magnesium sulfate had the antibiotic accumulated inside the cells be liberated into the outside, and this effect resulted in improving the final antibiotic yield. The maximum antibrotic yield was obtained when 100 mM magnesium sulfate was added after one day of cultivation, and enhanced more than three times compared to that of the control to which it was not added.

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THE EFFECT OF DIETARY MAGNESIUM LEVEL ON THE MAGNESIUM METABOLIZABILITY IN LAYING TSAIYA DUCK AND LEG HORN HEN

  • Ding, S.T.;Shen, T.F.
    • Asian-Australasian Journal of Animal Sciences
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    • v.5 no.2
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    • pp.225-228
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    • 1992
  • The study was undertaken to determine the effect of various levels of dietary magnesium on the metabolizability of magnesium in laying Tsaiya ducks and Leghorn hens. Twenty-five Tsaiya ducks and 25 Leghorn hens were raised in individual cages. The basal diet was mainly consisted of corn starch and isolated soybean protein. At the beginning of the experiments, birds were fed the basal diet added with 500 mg/kg Mg (1070 mg/kg in total by analysis) for 10 days in order to make the birds adapt to the new diet. Then, they were randomly divided into five treatments with five birds for each treatment and fed the experimental diets containing 690, 1070, 1690, 2150 or 2380 mg/kg Mg for 21 days and during the last five days excreta were collected. The experiment was repeated three times each at the age of 25, 31 and 36 weeks. The metabolizability of magnesium in the diet was determined by the indicator method. The metabolizabilities of magnesium for Tsaiya duck and Leghorn hen were 59.9% and 62.5%, respectively as the diet contained 690 mg/kg magnesium, and were significantly decreased (p<0.05) to 39.7 and 30.7%, respectively when the dietary magnesium content was increased to 2380 mg/kg.