• Title, Summary, Keyword: Magnesium

Search Result 2,609, Processing Time 0.041 seconds

The Brightness Change of Fractured Surface in Accordance with Inclusion Contents of Magnesium Alloy (마그네슘합금내 개재물 함유량에 따른 파단면의 명도변화)

  • Kim, Hyun Sik;Ye, Dea Hee;Kang, Min Cheol;Kim, Jung Dae;Jeong, Hae Yong
    • Journal of Korea Foundry Society
    • /
    • v.34 no.6
    • /
    • pp.200-213
    • /
    • 2014
  • Pure magnesium and magnesium alloys have been applied to various kinds of industrial fields, especially automotive and electronic parts. These parts are manufactured mainly through a diecasting process. These days, magnesium ingots are used as raw material, and recycled ingots are often used for commercial purposes. But the quality of virgin magnesium and recycled ingots is not secure. Therefore, massive casting defects can occur, and some things manufactured can be damaged by these defects. This study evaluated the inclusions of virgin magnesium and recycled ingot. It also included composition analysis by spectrometer, measuring inclusion contents by SEM & EDS, and performing a brightness test on fractured surfaces. The brightness test is generally very easy and obtains results quickly, so its results have been compared with the results obtained from various test methods. From the test results, we obtained a satisfactory result in evaluating inclusion and oxide. The brightness values are lower as the inclusion contents are higher. When the brightness value is over 47 in AM50A and 44 in AZ91D, the mechanical properties are expected to be good.

Corrosion Behavior of AZ91 Magnesium Alloy (AZ91 마그네슘합금의 부식거동)

  • Yim, Chang Dong;Kim, Young Min;Park, Sung Hyuk;You, Bong Sun
    • Korean Journal of Metals and Materials
    • /
    • v.50 no.9
    • /
    • pp.619-627
    • /
    • 2012
  • One of the barriers limiting wide applications of magnesium alloys to various industries is their poor corrosion resistance. The corrosion properties of AZ91 magnesium alloy, which is the most popular magnesium casting alloy, are affected by microstructural and environmental factors. The corrosion properties of AZ91 magnesium alloy are affected by the corrosion properties of ${\alpha}-Mg$ and ${\beta}$ phases, the volume fraction and distribution of ${\beta}$ phase and area ratio of ${\alpha}-Mg/{\beta}$ phases. The corrosion properties of AZ91 magnesium alloy under various environments also change according to the passivity of films and types of corrosion products formed on its surface. The corrosion resistance of the magnesium alloys can be improved by microstructural control through the addition of alloying elements and optimization of the production process.

Osteoblast adhesion and differentiation on magnesium titanate surface (마그네슘 티타네이트 표면의 조골세포 부착도와 분화)

  • Choi, Seung-Min;Lee, Jae-Kwan;Ko, Sung-Hee;Um, Heung-Sik;Chang, Beom-Seok
    • Journal of Periodontal and Implant Science
    • /
    • v.35 no.4
    • /
    • pp.851-861
    • /
    • 2005
  • The nature of the implant surface can directly influence cellular response, ultimately affecting the rate and quality of new bone tissue formation. The aim of this in vitro study was to investigate if human osteoblast-like cells, Saos-2, would respond differently when plated on disks of magnesium titanate and machined titanium. Magnesium titanate disks were prepared using Micro Arc Oxidation(MAO) methods. Control samples were machined commercially pure titanium disks. The cell adhesion, proliferation and differentiation were evaluated by measuring cell number, and alkaline phosphatase(ALPase) activity at 1 day and 6 day after plating on the titanium disks. Measurement of cell number and ALPase activity in Saos-2 cells at 1 day did not demonstrate any difference between machined titanium and magnesium titanate. When compared to machined titanium disks, the number of cells was reduced on the magnesium titanate disks at 6 day, while ALPase activity was more pronounced on the magnesium titanate. Enhanced differentiation of cells grown on magnesium titanate samples was indicated by decreased cell proliferation and increased ALPase activity.

Corrosion Behavior of AZ31 Magnesium Alloy during Machining (AZ31 마그네슘 합금의 절삭가공과정에서의 부식거동)

  • Kim, Jae-Hak;Kwon, Sung-Eun;Lee, Seung-Jae
    • Journal of the Korea Institute of Military Science and Technology
    • /
    • v.15 no.3
    • /
    • pp.315-321
    • /
    • 2012
  • In the study, corrosion characteristics of AZ31 magnesium alloy under various environments exposed during machining(immersion in cutting oil, 5 % cutting oil aqueous solution and distilled water & contact with dissimilar metals, SPC4 and A5052-H32) were investigated. A corrosion test was performed AZ31 magnesium alloy was immersed in each electrolyte solution after contacting with each dissimilar metals, and the results were observed by an electron microscope. In immersion tests, corrosion of AZ31 magnesium alloy showed to be in the sequence of distilled water> 5 % cutting oil aqueous solution> cutting oil> air, and in the test of contact with dissimilar metals, corrosion showed to be in the sequence of SPC4> A5052-H32> AZ31. It can be concluded that to prevent corrosion during machining, AZ31 magnesium alloy must prevent contacting water and use magnesium alloy for raw material of Jig & Fixture.

Combustive Properties of Low Density Polyethylene and Ethylene Vinyl Acetate Composites Including Magnesium Hydroxide (저밀도 폴리에틸렌과 에틸렌 비닐 아세테이트에 수산화마그네슘을 첨가한 복합체의 연소성)

  • Chung, Yeong-Jin
    • Fire Science and Engineering
    • /
    • v.25 no.5
    • /
    • pp.69-75
    • /
    • 2011
  • It was performed to test the combustive properties of low density polyethylene and ethylene vinyl acetate (LDPE-EVA) composite by the addition of magnesium hydroxide. Flame retardant of natural magnesium hydroxide was added to the mixture of LDPE-EVA in 40 to 80 wt% concentration. The composite was compounded to prepare specimen for combustive analysis by cone calorimeter (ISO 5660-1). Comparing with virgin LDPE-EVA, the specimens including the magnesium hydroxide had lower flashover possibility. It is supposed that the combustive properties in the composites decreased due to the endothermic decomposition of magnesium hydroxide. The specimens with magnesium hydroxide showed both the lower total heat release rate (THR) and lower CO production rate than those of virgin polymer. As the magnesium hydroxide content increases, the total smoke release (THR) and smoke extinction area (SEA) decreased.

Effects of Additions of Magnesium and Aluminum on the Graphite Morphology and Mechanical Properties of 3.6wt.%C-2.5wt.%Si Cast Iron Poured into Shell Stack Mold (쉘 스택 주조 3.6wt.%C-2.5wt.%Si 주철의 흑연 형상과 기계적 성질에 미치는 마그네슘 및 알루미늄 첨가의 영향)

  • Lee, Hag-Ju;Kwon, Hae-Wook
    • Journal of Korea Foundry Society
    • /
    • v.29 no.5
    • /
    • pp.204-212
    • /
    • 2009
  • The effects of addition of magnesium only and the simultaneous addition of magnesium and aluminum on the graphite morphology of the cast iron with the composition of 3.6wt.% and 2.5wt.%Si poured into shell stack mold were investigated. The nodularity and mechanical properties of the specimen with smaller cross-section were higher than those with langer one, when copper was not added. When the magnesium only was added, the nodularity was decreased with decreased residual magnesium content and the C. V, graphite was obtained with the magnesium content in the range of 0.010~0.015wt.%. When the magnesium and aluminum were added together, the nodularity was decreased with decreased residual magnesium and increased aluminum contents. When copper was added, the volume fraction of pearlite in the matrix, strength and hardness were higher and elongation was lower for specimen with smaller cross-section. The volume fraction of pearlite, strength and hardness were increased and the elongation was decreased with increased copper content for the specimen with C, V, graphite.

Noise Characteristics and Frequency Response Function on Implementation of AZ31 Magnesium Alloy to Automobile Hood Panel (AZ31 마그네슘합금의 자동차 Hood Panel적용에 따른 주파수응답 및 소음 특성의 변화)

  • Lee, Choong-Do;Yeo, Dong-Hoon
    • Transactions of the Korean Society of Automotive Engineers
    • /
    • v.19 no.1
    • /
    • pp.139-146
    • /
    • 2011
  • In present study, it aims to compare the noise and vibration characteristics between magnesium alloy and steel hood panel. The AZ31 magnesium hood panel was fabricated through warm forming process, and the noise and vibration characteristics between both hood panels was compared through the measurement of engine radiation noise and transmission loss, as well as FRF on modal analysis. The sound insulation performance of magnesium alloy was wholly superior to that of steel hood panel, even though the transmission loss of magnesium alloy is lower than that of steel due to mass effect primarily. The FRF characteristics on modal analysis indicates that the resonance frequency of magnesium hood panel is remarkably increased to higher value than that of steel hood panel. The radiation and interior noise of magnesium panel even without acoustic hood insulation were remarkably lower than those of steel hood panel with acoustic insulation, in particular, at a range below 4,000 rpm.

Effects of Ca Intake Levels on Mg Utilization in Rats of Different Ages (칼슘의 섭취수준이 연령이 다른 흰쥐의 마그네슘 이용에 미치는 영향)

  • 최미경;전예숙
    • Journal of Nutrition and Health
    • /
    • v.31 no.9
    • /
    • pp.1404-1410
    • /
    • 1998
  • The purpose of this study was to investigate the effects of calcium intake levels on magnesium utilization in young and adult rats fed various levels of calcium(50, 100 or 200% of requirement) for 3 weeks. Feed intake, body weight gain, and feed efficiency ratios of the young group were significantly higher than those of the adult group. In calcium levels of tissues, serum calcium levels in young group were higher than in the adult group and kidney calcium levels in HCa(high-calcium group) were higher than in other groups. There was no significant difference in magnesium intake among age and diet groups. However, magnesium excretions through feces and urine in the adult group were higher than in the young group. Therefore, magnesium retention in the young group was higher than in the adult group. Especially in the young group, fecal magnesium excretion was increased with increasing levels of dietary calcium. Serum magnesium levels were lowest in YHCa(young 8t high-calcium) group, and there was no significant difference in liver and kidney levels among the calcium-diet groups. These results indicate that high calcium consumption promotes of fecal magnesium excretion and decreased magnesium retention rates in growing rats. Therefore, it is suggested that mineral interactions should be considered in the supplementation of dietary calcium intake for growth. (Korean J Nutrition 31(9) 1404-1410, 1998)

  • PDF

A Study on the Mechanical Properties and Formability of Mg AZ31B Sheet (Mg AZ31B 판재의 기계적 특성과 성형성 분석)

  • Lee, G.H.;Yoon, T.W.;Kang, C.Y.
    • Transactions of Materials Processing
    • /
    • v.23 no.8
    • /
    • pp.495-500
    • /
    • 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.

Process Development for Automotive Hybrid Hood using Magnesium Alloy AZ31B Sheet (마그네슘 합금 AZ31B 판재를 이용한 자동차 하이브리드 후드 개발 프로세스)

  • Jang, D.H.
    • Transactions of Materials Processing
    • /
    • v.20 no.2
    • /
    • pp.160-166
    • /
    • 2011
  • Weight reduction while maintaining functional requirements is one of the major goals in the automotive industry. The use of lightweight magnesium alloys offers great potential for reducing weight because of the low density of these alloys. However, the formability and the surface quality of the final magnesium alloy product for auto-body structures are not acceptable without a careful optimization of the design parameters. In order to overcome some of the main formability limitations in the stamping of magnesium alloys, a new approach, the so-called "hybrid technology", has been recently proposed for body-in-white structural components. Within this approach, necessary level of mechanical joining can be obtained through the use of lightweight material-steel adhesion promoters. This paper presents the development process of an automotive hybrid hood assembly using magnesium alloy sheets. In the first set of material pairs, the selected materials are magnesium alloy AZ31B alloy and steel(SGCEN) as inner and outer panels, respectively. In order to optimize the design of the inner panel, the stamping process was analyzed with the finite element method (FEM). Laser welding by CW Nd:YAG were used to join the magnesium alloy sheets. Based on the simulation results and mechanical test results of the joints, the determination of die design variables and their influence on formability were discussed. Furthermore, a prototype based on the proposed design was manufactured and the static stiffness test was carried out. The results demonstrate the feasibility of the proposed hybrid hood with a weight reduction of 25.7%.