• 자원리싸이클링
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• 제24권3호
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• pp.3-10
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• 2015

코발트와 구리가 함유된 유기산 침출용액으로부터 용매추출법을 이용하여 구리와 코발트의 분리 회수를 위한 기초 연구를 실시하였다. 구리와 코발트의 추출에 영향을 미칠 수 있는 평형 pH, 추출제의 농도, 상비 변화에 대하여 용매 추출 실험을 진행하였다. 구리 추출제로 LIX 84, 코발트 추출제로 Cyanex 272 및 Versatic acid 10을 사용하였는데 실험 결과 구리의 경우 평형 pH 2.0 이상에서 약 99%의 추출율을 보였고, 코발트의 경우는 추출제로 Cyanex 272를 사용 시 평형 pH 6.0에서 Versatic acid 10 사용 시에는 평형 pH 7.5에서 각각 90% 이상의 추출율을 나타내었다. 한편, 구리와 코발트를 탈거하기 위한 탈거제로 최적의 황산농도는 120 ~ 150 g/L 이었다. 그리고 구리 및 코발트가 함유된 미생물 침출용액에서 구리와 코발트를 회수할 수 있는 기초 최적 공정을 제시하였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2010년도 제39회 하계학술대회 초록집
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• pp.41-41
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• 2010

반도체 소자의 선폭이 감소함에 따른 금속배선의 저항이 증가하면서 반도체 배선물질을 copper로 대체하려는 연구가 진행되고 있다. 그러나 copper를 금속배선에 사용하게 되면 대기 상에서 노출 시 쉽게 산화가 일어나며 형성된 산화물의 미세조직이 치밀하지 못하여 계속적인 산화가 진행되고, 후속 열처리 공정 시 copper가 유전체로 확산되어 소자의 정상적인 작동을 방해하게 되는 문제점을 가지고 있다. 이러한 문제점을 해결하기 위해서 copper의 확산 및 산화를 방지하는 물질로 cobalt가 각광받고 있다. Cobalt는 낮은 저항과 열적 안정성이 우수하여 copper와의 연동에 문제가 없으며, 소자의 작동에도 영향을 미치지 않는다. Cobalt 박막의 적용을 위해 patterning 단계를 줄일 수 있는 선택적 증착공정의 개발도 요구되고 있다. 본 연구에서는 우수한 층덮힘(step coverage)과 양질의 박막을 증착할 수 있는 MOCVD 공정을 이용하였고, cobalt 전구체로서 $Co(hfac)_2$ (hfac: hexafluoroacethylacetonate) 전구체와 $Co_2$ (CO)8 (CO: carbonyl) 전구체를 사용하였다. 각각의 전구체에 따라 선택적 증착이 가능한 공정조건을 찾기 위한 연구를 진행하였다.

• 한국식품영양과학회지
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• 제19권5호
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• pp.418-428
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• 1990

This study measured each daily intake and excretion of iron copper and cobalt of eight 20-26 years old college men during four weeks by means of analyzing their food intake urine and feces keeping their normal living pattern and maintenance body weight. This study also compared the actual measurement value of iron intake by atomic absorption spectrophoto-meter with the conversion value of it by food table. The results were as follows. Each person's average intake daily was iron 9.19±0.32mg/day, copper 0.56±0.06mg/day and cobalt 1.86±0.18mg/day. Each person's average urinary excretion daily was iron 0.53±0.07mg/day, copper 0.07±0.03mg/day and cobalt 0.13±0.01mg/day. Each person's average fecal excretion daily was iron 1.73±0.14mg/day copper 0.16±0.01mg/day and cobalt 0.46±0.08mg/day. The actual measurement value was 9.19±0.32mg/day and its conversion value 14.07±0.29mg/day : the former was 35% lower than the latter.

• 한국식품영양과학회지
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• 제20권1호
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• pp.78-88
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• 1991

본 연구는 21~23세의 여자 대학생 8명을 대상으로 4주간 평상시와 같은 생활 양식과 적정 체중을 유지 시키면서 각 대상자들이 섭취한 모든 음식과 배설한 대변 및 소변을 수거하여 iron, copper 및 cobalt의 함량을 측정하여 1인 1일당 섭취량과 배설량을 측정하였다. Iron 섭취량은 원자 흡광광도계로 측정한 설측치와 식품 분석표에 의거하여 얻은 환산치와의 관계를 비교하였다. 그 성적을 요약하면 다음과 같다. 1일 1인당 각 대상자별 평균 섭취량은 iron $13.85{\pm}1.10mg/day,\;copper\;1.44{\pm}0.14mg/day\;그리고\;cobalt는\;3.25{\pm}0.18mg/day$이었다. 1일 1인당 각 대상별 소변으로의 평균 배설량은 iron $1.38{\pm}0.27mg/day\;copper\;0.06{\pm}0.01mg/day\;그리고\;cobalt\;0.59{\pm}0.07mg/day$이었다. 1일 1인당 각 대상자별 대변으로의 평균 배설량은 iron $7.66{\pm}0.79mg/day\;copper\;0.59{\pm}0.11mg/day\;그리고\;cobalt\;0.94{\pm}0.16mg/day$이었다. Iron의 실측치는 $13.85{\pm}1.10mg/day$이었고 환산치는 $15.26{\pm}1.17mg/day$로 실측치가 환산치에 비하여 9% 낮았다.

• 한국표면공학회지
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• 제54권3호
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• pp.124-132
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• 2021

Graphene which grown on the cobalt or nickel sputtered copper foil depending on the annealing time was studied. Graphene on the copper foil grown by chemical vapor deposition was compared to those on cobalt or nickel sputtered copper foil by using a RF (Radio Frequency) magnetron sputtering at room temperature. FLG(few-layer graphene) was identified independent of substrates by Raman and X-Ray Photoelectron Spectroscopy analyses. On copper foil, size and area fraction of the graphene growth increased until 30 minutes annealing and then didn't changed. Comparing to that, graphene on the cobalt refined till 50 minutes annealing, after then the effect disappeared which means a similar shape to that on copper foil. On nickel the graphene refined irrespective of annealing time that is possibly because of the complete solid solution of nickel with copper.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.377-377
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• 2012

Microprocessor technology now relies on copper for most of its electrical interconnections. Because of the high diffusivity of copper, Atomic layer deposition (ALD) $TaN_x$ is used as a diffusion barrier to prevent copper diffusion into the Si or $SiO_2$. Another problem with copper is that it has weak adhesion to most materials. Strong adhesion to copper is an essential characteristic for the new barrier layer because copper films prepared by electroplating peel off easily in the damascene process. Thus adhesion-enhancing layer of cobalt is placed between the $TaN_x$ and the copper. Because, cobalt has strong adhesion to the copper layer and possible seedless electro-plating of copper. Until now, metal film has generally been deposited by physical vapor deposition. However, one draw-back of this method is poor step coverage in applications of ultralarge-scale integration metallization technology. Metal organic chemical vapor deposition (MOCVD) is a good approach to address this problem. In addition, the MOCVD method has several advantages, such as conformal coverage, uniform deposition over large substrate areas and less substrate damage. For this reasons, cobalt films have been studied using MOCVD and various metal-organic precursors. In this study, we used $C_{12}H_{10}O_6(Co)_2$ (dicobalt hexacarbonyl tert-butylacetylene, CCTBA) as a cobalt precursor because of its high vapor pressure and volatility, a liquid state and its excellent thermal stability under normal conditions. Furthermore, the cobalt film was also deposited at various $H_2/NH_3$ gas ratio(1, 1:1,2,6,8) producing pure cobalt thin films with excellent conformality. Compared to MOCVD cobalt using $H_2$ gas as a reactant, the cobalt thin film deposited by MOCVD using $H_2$ with $NH_3$ showed a low roughness, a low resistivity, and a low carbon impurity. It was found that Co/$TaN_x$ film can achieve a low resistivity of $90{\mu}{\Omega}-cm$, a low root-mean-square roughness of 0.97 nm at a growth temperature of $150^{\circ}C$ and a low carbon impurity of 4~6% carbon concentration.

• Asian-Australasian Journal of Animal Sciences
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• 제20권9호
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• pp.1433-1437
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• 2007

Two field trials were carried out to evaluate the performance of a soluble glass copper, cobalt and selenium bolus for maintaining adequate levels of the three trace elements in yaks. Forty yaks were used in trial 1 and 60 yaks were used in trial 2. In each trial two commercial soluble glass boluses were administered to half of the yaks. Blood samples were taken from the jugular vein at day 0, 30, 60, 90 in trial 1 and at day 0, 45, 75 and 105 in trial 2. The samples were analysed for copper status (serum caeruloplasmin activity and copper concentration), cobalt status (serum vitamin $B_{12}$ concentration and cobalt concentration), selenium status (erythrocyte glutathione peroxidase activity and selenium concentration) and serum zinc concentration. The erythrocyte glutathione peroxidase activities, serum caeruloplasmin activities and serum vitamin $B_{12}$ concentrations for trial 1 and 2 were all significantly increased for the bolused yaks (p<0.001 or p<0.01) on all sampling days. The bolused yaks had a significantly higher selenium and copper status in serum than the control yaks on all sampling days in trial 1 and 2 (p<0.05 or p<0.01). There were no significant differences in zinc and cobalt concentrations between the bolused yaks and the controls.

• 자원리싸이클링
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• 제22권2호
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• pp.44-52
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• 2013

코발트 정광으로부터 코발트와 구리의 회수를 위하여 3종의 Aspergillus niger 균을 이용하여 각 금속의 침출거동을 조사하였다. 주요 실험 변수로는 균주 종류에 따른 유기산 생성량, pH 및 고액농도비 등 이었다. 실험결과 유기산(구연산 및 옥살산) 생성양의 경우 A. niger KCTC 6144가 Malt Extract Broth 배지에서 초기 pH 3.5에서 가장 좋았다. 한편 코발트 및 구리 침출실험결과로는 A. niger KCTC 6985를 사용한 경우가 효과적이었는데, 고액농도 10 g/L인 경우, pH 3.5, $24^{\circ}C$에서 약 15일 경과 후 코발트의 경우는 82%, 구리는 98%의 침출율을 나타내었다.

• 한국분말재료학회지
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• 제29권3호
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• pp.252-261
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• 2022

Cobalt is a vital metal in the modern society because of its applications in lithium-ion batteries, super alloys, hard metals, and catalysts. Further, cobalt is a representative rare metal and is the 30th most abundant element in the Earth's crust. This study reviews the current status of cobalt extraction and recycling processes, along with the trends in its production amount and use. Although cobalt occurs in a wide range of minerals, such as oxides and sulfides of copper and nickel ores, the amounts of cobalt in the minerals are too low to be extracted economically. The Democratic Republic of Congo (DRC) leads cobalt mining, and accounts for 68.9 % of the global cobalt reserves (142,000 tons in 2020). Cobalt is mainly extracted from copper-cobalt and nickel-cobalt concentrates and is occasionally extracted directly from the ore itself by hydro-, pyro-, and electro-metallurgical processes. These smelting methods are essential for developing new recycling processes to extract cobalt from secondary resources. Cobalt is mainly recycled from lithium-ion batteries, spent catalysts, and cobalt alloys. The recycling methods for cobalt also depend on the type of secondary cobalt resource. Major recycling methods from secondary resources are applied in pyro- and hydrometallurgical processes.

• Journal of Magnetics
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• 제11권3호
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• pp.119-122
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• 2006

We electroplated copper-cobalt thin films on a silicon substrate, which had 150 nm thick copper seed layer. The adhesion between the two metallic layers could be increased by utilizing a proper organic additive, pulse plating technique, and high temperature annealing. The thin films exhibited columnar growth of the deposits and enhanced adhesion. This is attributed to the grain growth mechanism introduced by the additive and annealing.