• 한국주조공학회지
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• 제34권3호
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• pp.94-99
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• 2014

A commercially used Zr-based amorphous alloy was recycled and the effects of introducing carbon during recycling on the glass forming ability and mechanical properties of the alloy were investigated. The initial carbon content used in this study was 229ppm. The carbon content was gradually increased as the number of recycling iterations was increased and after the $4^{th}$ recycling it rapidly increased. As return scrap was recycled, polygonal particles precipitated, and they were identified as ZrC. The amount of the precipitates also increased with recycling. Tg, Tx and ${\Delta}T$ of the base alloy were 615 K, 696 K and 81 Kr respectively and they changed to 634 K, 706 K and 72 K after the $10^{th}$ recycling. The decrease of the ${\Delta}T$ value indicates deterioration of the glass forming ability. Hardness was not changed during three iterations of recycling but after the $4^{th}$ recycling it significantly increased. This is ascribed to an increase of amount of the hard particles, namely ZrC.

• 한국주조공학회지
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• 제40권3호
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• pp.85-96
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• 2020

The effect of an aluminum scrap addition ratio on the tensile and solidification cracking properties of the AC4A aluminum alloy in the as-cast state and heat-treated state were investigated in this study. Generally, the expected problem of using scrap in aluminum casting is an increase of hydrogen and Fe element inside the aluminum melt. Another issue is an oxide film which has a weak interface with the molten aluminum and acts as potent nucleation sites for internal porosity and crack initiation. Solidification cracking is one of the critical defects that must be resolved to produce high quality castings. A conventional evaluation method for solidification cracking is a relative and qualitative analysis method which does not provide quantitative data on the thermal stress in the solidification process. Therefore, a newly designed solidification cracking test apparatus was used in this study, and the device can provide quantitative data. As a result, after conducting experiments with different scrap addition ratios (0%, 20%, 35%, 50%), the tensile strengths and elongations in the as-cast state were 214, 187.7, 182.1 and 170.4MPa and 4.6%, 3.4%, 3.1% and 2.3%, respectively. In the case of the T6 heat-treated state, the tensile strengths and elongations were 314.9, 294.6, 293.1 and 271.1MPa and 5.4%, 4.6%, 3.8% and 3.1%, respectively. The strength of the solidification cracking was 3.1, 2.4, 2.2and 1.6MPa as the scrap addition ratio increases.

• 마이크로전자및패키징학회지
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• 제24권1호
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• pp.1-8
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• 2017

Fe-9.8Si-6.0Al mother alloy was manufactured using by Fe-3.5Si recycled scrap and Si powder. And then, soft magnetic alloy powder of $D_{50}$ size and sphere type were prepared by gas atomization process. To obtain the soft magnetic powder of a high aspect ratio, in the first, we conducted the ball milling process for 8 hours. And heat treatment was performed under $650^{\circ}C$, 2 hours and $N_2$ atmosphere condition for reducing the residual stress of the powder. Based on these process, we made around $50{\mu}m$ diameter Fe-9.8Si-6.0Al powder, which morphology and shape was a similar to the commercial Fe-Si-Al powder. Finally, the soft magnetic sheets were prepared by tape casting process using by those powders. The permeability of the tape casting sheet was measured, and we confirmed the possibility of reusing to the soft magnetic materials of Fe-Si electric sheet scrap.

• 접착 및 계면
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• 제9권2호
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• pp.16-23
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• 2008

본 연구에서는 산업현장에서 직물 제직 시 스크랩으로 버려지는 폐양모와 범용 열가소성수지인 폴리프로필렌(PP)으로 구성된 새로운 폐양모/PP NFRPs (Natural Fiber Reinforced Polymer Composites: 천연섬유강화 고분자복합재료)를 압축성형 방법으로 제조한 후 그들의 기계적, 열적 특성을 분석하였다. PP수지의 기계적 특성은 폐양모의 도입으로 두드러지게 향상되었다. 특히 폐양모의 함량을 50 vol%로 하여 NFRP를 제조하였을 때, PP 대비 NFRP의 굴곡강도는 약 20%, 굴곡탄성률은 약 143%까지 향상되었으며, 인장강도는 약 76%, 인장탄성률은 약 90% 크게 향상되었다. 그리고 열변형온도(HDT)는 최고 $138^{\circ}C$로 PP 대비 약 $21^{\circ}C$가 증가되는 결과를 보여주었다. 연구결과는 열가소성 매트릭스 수지의 보강소재로서 폐양모의 적용 가능성을 제시하였다.

• 자원리싸이클링
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• 제11권4호
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• pp.11-16
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• 2002

폐자동차 파쇄를 통한 주요구성물질의 분리 및 분석평가를 위한 현장실험을 수행하였다. 모재인 폐자동차 차피로는 국내 자동차 업체에서 제작한 Sonata II, Sephia 및 Prince의 3종을 선택하여 엔진부분과 타이어 및 문짝 등을 미리 제거하고 압축된 상태로 제공받았다. 현장설비의 주요 공정은 pre- 및 main-shredder, 분급기, 자선기, 와류선별기 및 수작업 분리로 구성되어 있었다. shredder 산물의 현장 분리실험결과 철 스크랩이 전체의 60.1%를 차지하여 가장 비중이 높았으며, 알루미늄, 구리 및 아연 등의 비철금속류는 약 2％ 정도인 것으로 나타났다. Light fluff는 fluff 전체 중량의 90% 정도를 차지하는 것으로 관찰되었으며, 5cm undersize 가 70.5%로써 대부분이었고 나머지는 플라스틱, 섬유 및 스폰지 등으로 구성되어 있었다 heavy fluff의 경우에는 고무와 플라스틱이 주구성물질인 것으로 나타났으며, 발열량의 경우 플라스틱이 10,000 cal/gr을 상회하여 가장 높았고 가죽과 고무류가 각각 10.3 및 2.55 wt％의 비교적 높은 CI함량을 보였다.

• 자원리싸이클링
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• 제21권3호
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• pp.56-64
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• 2012

일반적으로 인쇄회로기판(Printed Circuit Board, PCB)은 다양한 종류의 플라스틱에 세라믹과 금속 성분이 복합적으로 함유되어 있는 것으로 알려져 있다. 따라서 환경적인 보호뿐만 아니라 자원의 재활용의 관점에서 PCB 스크랩으로부터 금속 성분을 분리해내는 것은 중요하다. 본 연구에서는 PCB의 재활용 기술에 대한 특허와 논문을 분석하였다. 분석 범위는 1980년~2011년까지의 미국, 유럽연합, 일본, 한국 등 다양한 나라의 등록/공개된 특허와 SCI 논문으로 제한하였다. 특허와 논문은 키워드를 사용하여 수집하였고, 기술의 정의에 의해 필터링 하였다. 특허와 논문의 동향은 연도, 국가, 기업, 기술에 따라 분석하여 나타내었다.

• 한국주조공학회지
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• 제36권2호
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• pp.67-74
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• 2016

The effects of scrap content on the hot tearing property and tensile property were investigated in AC2BS alloy. The hot tearing strengths were $16.4kgf/cm^2$, $15.2kgf/cm^2$, $14.9kgf/cm^2$ and $13.3kgf/cm^2$, respectively, under the constant solid fraction of 29.3% when the scrap contents of the specimens were 0%, 20%, 35% and 50%. In the same way, tensile strengths of the as-cast condition were $24.5kgf/mm^2$, $23.7kgf/mm^2$, $17.3kgf/mm^2$ and $16.0kgf/mm^2$, respectively, and the corresponding tensile strengths of the T6 heat treatment condition were $27.2kgf/mm^2$, $26.7kgf/mm^2$, $24.2kgf/mm^2$ and $23.9kgf/mm^2$. Hot tearing strength and tensile strength decreased as scrap content of the specimen increased. According to the evaluation of the quantitative hot tearing and tensile test results, the decrease of these strengths is due to the presence of oxide films which act as crack initiation site of the specimens. Therefore, elimination of oxide films of aluminum melt to maintain melt cleanliness is required.

• 한국재료학회지
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• 제13권4호
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• pp.239-245
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• 2003

In order to explore the possibility to extract precious metals from PCB(Printed Circuit Board) scrap by gravity separation, a high temperature melting process was adopted, from the recycling view point, to investigate the influence of viscosity on A1$_2$$O_3$-CaO$-SiO_2$ slag system composed of PCB scrap. For optimizing the pre-treatment process of PCB scrap, an experimental condition for the complete calcination and oxidation of organic materials in PCB scrap was established and a quantitative analysis of oxidized PCB scrap was also carrie out. It was found that 6 hours were enough for the complete oxidation of PCB scrap at 1273 K in an atmosphere condition. A slag, l5wt%$A1_2$$O_3$-45wt%CaO-40wt%SiO$_2$, was chosen as a basic slag composition which is determined based on the quantitative analysis of PCB scrap. Viscosities were measured in slag systems both made from pure fluxes and from PCB scrap with additional fluxes. Slag viscosities composed of pure fluxes were measured to be 5.29 poise and 30.52 poise at temperatures of 1773 and 1573 K, whereas that of PCB scrap with additional fluxes were 3.37 poise and 69.89 poise, respectively.

• 한국응용과학기술학회지
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• 제25권1호
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• pp.58-64
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• 2008

Pretreatment of eliminating FFA is needed to make biodiesel from animal fat recovered from leather wastes because its acid value is high. This study was carried out to investigate the influence of 4 different pretreatment methods, which are heterogeneous catalyst method, ion exchange resin method, low pressure.high temperature method, and alkali method on the eliminating FFA and fatty acid composition. The results showed that the rate of eliminating FFA increased in the order of alkali method > catalyst method > low pressure high temperature method > ion exchange method. In the case of pretreatment of alkali method using NaOH, the rate of eliminating FFA appeared more than 86% regardless of acid value. Therefore, it was considered that alkali method using NaOH was the most effective in the view of economical and productive aspects, taking it into account that the acid value of animal fat recovered from fleshing scrap generated during leather making processes was 7 to 8.

• 콘크리트학회논문집
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• 제24권3호
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• pp.267-273
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• 2012

이 연구에서는 전기로 산화슬래그 골재를 사용한 철근콘크리트 기둥의 휨 성능을 평가하고자 한다. 전기로 산화슬래그는 철 스크랩을 제련하는 과정에서 얻어지는 부산물이다. 전기로 산화슬래그는 천연 광물과 유사한 석회(CaO)와 실리카($SiO_2$)가 주성분이기 때문에 콘크리트용 골재로 이용 가능하다. 이 연구에서는 골재종류를 실험변수로 총 3체의 직사각형 기둥 실험체를 제작하고 휨 실험을 수행하였다. 모든 실험체는 실험구간에서 $250{\times}250$ (mm)의 단면과 1,500 mm의 높이를 가지며, 반복 역대칭 모멘트와 일정한 축력을 받도록 계획하였다. 실험 결과 전기로 산화슬래그 골재를 사용한 실험체가 천연골재를 사용한 실험체보다 동등 이상의 휨 성능을 가짐을 알 수 있었다.