• Title/Summary/Keyword: Virgin magnesium

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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
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    • v.34 no.6
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    • pp.200-213
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    • 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.

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
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    • v.25 no.5
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    • pp.69-75
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    • 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.

Combustion-Retardation Properties of Low Density Polyethylene and Ethylene Vinyl Acetate Mixtures with Magnesium Hydroxide (수산화마그네슘이 첨가된 저밀도 폴리에틸렌과 에틸렌 비닐 아세테이트 혼합물의 난연성)

  • Chung, Yeong-Jin;Lim, Hyung Mi;Jin, Eui;Oh, JungKyoo
    • Applied Chemistry for Engineering
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    • v.22 no.4
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    • pp.439-443
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    • 2011
  • It was performed to test the combustive properties of low density polyethylene and ethylene vinyl acetate (LDPE-EVA) mixture 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 combustive properties. It is supposed that the combustion-retardation properties in the composites improved due to the endothermic decomposition of magnesium hydroxide. The specimens with magnesium hydroxide showed both the lower peak heat release rate (PHRR) and lower effective heat of combustion (EHC) than those of virgin polymer. As the magnesium hydroxide content increases, time to ignition increased and the peak heat release rate decreased.

Current Status of Titanium Recycling Technology (타이타늄의 리사이클링 기술 현황)

  • Sohn, Ho-Sang
    • Resources Recycling
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    • v.30 no.1
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    • pp.26-34
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    • 2021
  • Titanium is the fourth most abundant structural metal, after aluminum, iron, and magnesium. However, it is classified as a 'rare metals', because it is difficult to smelt. In particular, the primary titanium production process is highly energy-intensive. Recycling titanium scraps to produce ingots can reduce energy consumption and CO2 emissions by approximately 95 %. However, the amount of metal recycled from scrap remains limited of the difficulty in removing impurities such as iron and oxygen from the scrap. Generally, high-grade titanium and its alloy scraps are recycled by dilution with a virgin titanium sponge during the remelting process. Low-grade titanium scrap is recycled to ferrotitanium (cascade recycling). This paper provides an overview of titanium production and recycling processes.