• 한국표면공학회지
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• 제15권1호
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• pp.11-18
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• 1982

80% Ni-Permalloy is soft magnetic material with high initial permeability and low magnetic coercive force Hc, and is used to computer memory cores and minirelays of communication e-ngineering. In this paper 80 Permalloy thin film on copper cathode was alloy-deposited from Watts so-lution contatining FeSO4$.$7H2O. The amount of FeSO4$.$7H2O in the solution, pH, temperature of the solution and plating current density were varied as parameters and the resulting comp-osition changes of deposited film were analyzed electrochemically with respect to the parame-ters. From the above procedure electroplating conditions for deposition of 80 Permalloy were est-ablished as following: 17-21 g/$\ell$ of FeSO4$.$7H2O in Watts solution, current density 1.0-2.0 Amp/dm2, pH 2.5-3.0 and temperature range of 50-60$^{\circ}C$.

• 마이크로전자및패키징학회지
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• 제19권4호
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• pp.65-69
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• 2012

복합도금이란 금속 도금층을 매트릭스로 세라믹, 폴리머, 나노분말과 같은 입자를 공석시켜 경도의 향상, 내마모성, 내식성, 자기 윤활성 등의 특성을 갖는 복합 금속피막을 얻어내는 방법으로 본 연구에서는 나노입자로 $TiO_2$를 사용하여 니켈과 함께 복합도금층을 형성하였다. $TiO_2$를 첨가시킨 복합전기도금을 통해 표면저항성 향상, 광분해 효과를 기대할 수 있다. 용액조건 중 pH 변화에 따른 zeta전위를 측정하였다. 초음파처리를 통한 물리적인 방법으로 용액 중 나노분말의 응집을 최소화한 후 $TiO_2$-Ni 복합도금을 실시하였다. 최적의 도금 조건으로 $50^{\circ}C$에서 pH 3.5, 전류밀도 $40mA/cm^2$에서 가장 효과적이었으며 Ti의 함량은 $50^{\circ}C$에서 15-20 at.%로 확인되었다.

• Corrosion Science and Technology
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• 제11권6호
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• pp.275-279
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• 2012

Ni-W alloy deposits have lately attracted the interest as an alternative surface treatment method for hard chromium electrodeposits because of higher wear resistance, hardness at high temperature, and corrosion resistance. This study deals with influences of process variables, such as electodeposition current density, plating temperature and pH, on the internal stress of Ni-W nanocrystalline deposits. The internal stress was increased with increasing the applied current density. With increasing applied current density, the grain size of the deposit decreases and concentration of hydrogen in the deposit increases. The subsequent release of the hydrogen results in shrinkage of the deposit and the introduction of tensile stress in the deposit. Consequently, for layers deposited at high current density, cracking occurs readily owing to high tensile stress value. By increasing the temperature of the electrodeposition from $60^{\circ}C$ to $80^{\circ}C$, the internal stress was decreased. It seems that an increase in the number of active ions overcoming the activation energy at elevated temperature caused a decline in the concentration polarization and surface diffusion. It decreased the level of hydrogen absorption due to the lessened hydrogen evolution reaction. Therefore, the lower level of hydrogen absorption degenerated the hydride on the surface of the electrode, resulting in the reduction of the internal stress of the deposits. By increasing the pH of the electrodeposition from 5.6 to 6.8, the internal stress in the deposits were slightly decreased. It is considered that the decrease in internal stess of deposits was due to supply of W complex compound in cathode surface, and hydrogen ion resulted from decrease of activity.

• 자원리싸이클링
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• 제20권6호
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• pp.28-36
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• 2011

황산용액 중에 존재하는 니켈을 회수하기 위해 이온교환수지법을 이용한 기초연구를 수행하였다. 제조된 모의 니켈(Ni)용액에 독일 Lanxess사(社)의 Lewatit Monoplus TP 220를 이용하여 회분식 실험을 하였다. 흡착반응에 영향을 미치는 온도, 교반속도, 반응시간, pH, 이온교환수지 양, 니켈이온농도 등에 대해 고찰하였다. 초기 pH(2.0~5.0)와 교반속도는 니켈의 흡착에 거의 영향을 미치지 않았으며, 평형에 도달하기 위하여 72시간의 시간이 필요했다. 평형실험결과 Freundlich 흡착등온식에 적합하였고, 흡착반응속도는 유사 2차 반응 모델(pseudo-second order)로 잘 모사되었다. 한편 니켈을 함유한 실제 도금세정폐액의 흡착 실험을 행하여 모의용액의 흡착거동과 비교하였고, 흡착된 니켈은 황산 농도가 높아짐에 따라 수지로부터 효과적으로 용리되었다.

• Environmental Engineering Research
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• 제23권3호
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• pp.301-308
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• 2018

We investigated simultaneous removal of heavy metals such as Cr, Ni, and Zn by adsorption onto powdered activated carbon (PAC) and PAC modified with sodium diethyldithiocarbamate (PAC-SDDC). Modification of PAC was confirmed by Fourier transform infrared spectroscopy and Scanning electron microscopy and energy dispersive X-ray spectroscopy. Both PAC and PAC-SDDC reached adsorption equilibrium within 48 h, and the adsorption kinetics followed a pseudo-second order reaction kinetics. The removal of metals was enhanced with increasing both adsorbent dosage and followed the descending order of Cr > Ni > Zn for PAC and Cr > Zn > Ni for PAC-SDDC, respectively. Adsorption kinetics followed pseudo-second order kinetics. Adsorption kinetic results were well fitted by the Freundlich isotherm except for Cr adsorption onto PAC. The optimum pH for heavy metal adsorption onto PAC was 5, whereas that for PAC-SDDC ranged from 7 to 9, indicating that modification of PAC with SDDC significantly enhanced heavy metal adsorption, especially under neutral and alkaline pH conditions. Our results imply that SDDC modified PAC can be applied to effectively remove heavy metals especially Cr in plating wastewaters without adjusting pH from alkaline to neutral.

• Advances in nano research
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• 제12권5호
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• pp.457-465
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• 2022

The potentials of Ni_xZn_1-xFe₂O₄ (x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0) nanoadsorbents were investigated for removal of Cd and Cr from contaminated water from an electroplating industry in Himachal Pradesh, India. Optimal values were recorded under batch adsorption experiments performed to remove dissolved heavy metal ions from industrial wastewater. The specific surface area (SSA) of nanoadsorbents perceived to vary in a range 35.75-45.29 cm²/g and was calculated from the XRD data. The influence of two operating parameters, contact time and dopant (Ni) concentration was also investigated at pH ~7 with optimum dosage. Kinetic studies were conducted within a time range of 2-10 min with rapid adsorption of cadmium and chromium ions onto Ni_0.2Zn_0.8Fe₂O₄ nanoadsorbents. Pseudo-second-order kinetic model was observed to be well fitted with the adsorption data that confirmed the only existence of chemisorption throughout the adsorption process. The maximum adsorption efficiency values observed for Cd and Cr were 51.4 mg/g and 40.12 mg/g, respectively for different compositions of prepared series of nanoadsorbents. The removal percentage of Cd and Cr was found to vary in a range of 47.7%-95.25% and 21%-50% respectively. The prepared series of nanoferrite found to be suitable enough for adsorption of both heavy metal ions.

• 한국전기전자재료학회논문지
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• 제16권2호
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• pp.120-124
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• 2003

This paper describes a MEMS-based micro-fluxgate magnetic sensing element using Ni$\_$0.8/Fe$\_$0.2/ film formed by electroplating. The micro-fluxgate magnetic sensor composed of a thin film magnetic core and micro-structure solenoids for the pick-up and the excitation coils, is developed by using MEMS technologies in order to take advantage of low-cost, small size and lower power consumption in the fabrication. A copper with 20${\mu}$m width and 3${\mu}$m thickness is electroplated on Cr (300${\AA}$) / Au (1500${\AA}$) films for the pick-up (42turn) and the excitation (24turn) coils. In order to improve the sensitivity of the sensing element, we designed the magnetic core into a rectangular-ring shape to reduce the magnetic flux leakage. An electroplated permalloy film with the thickness of 3${\mu}$m is obtained under 2000 gauss to induce magnetic anisotropy. The magnetic core has the high DC effective permeability of ~1,100 and coercive field of ~0.1 Oe. The fabricated sensing element using rectangular-ring shaped magnetic film has the sensitivity of about 150 V/T at the excitation frequency of 2 MHz and the excitation voltage of 4.4 V$\_$p p/. The power consumption is estimated to be 50mW.

• 한국재료학회지
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• 제23권12호
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• pp.695-701
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• 2013

To understand how reactivity between reinforcing nanoparticles and aqueous solution affects electrodeposited Cu thin films, two types of commercialized cerium oxide (ceria, $CeO_2$) nanoparticles were used with copper sulfate electrolyte to form in-situ nanocomposite films. During this process, we observed variation in colors and pH of the electrolyte depending on the manufacturer. Ceria aqueous solution and nickel sulfate ($NiSO_4$) aqueous solutions were also used for comparison. We checked several parameters which could be key factors contributing to the changes, such as the oxidation number of Cu, chemical impurities of ceria nanoparticles, and so on. Oxidation number was checked by salt formation by chemical reaction between $CuSO_4$ solution and sodium hydroxide (NaOH) solution. We observed that the color changed when $H_2SO_4$ was added to the $CuSO_4$ solution. The same effect was obtained when $H_2SO_4$ was mixed with ceria solution; the color of ceria solution changed from white to yellow. However, the color of $NiSO_4$ solution did not show any significant changes. We did observe slight changes in the pH of the solutions in this study. We did not obtain firm evidence to explain the changes observed in this study, but changes in the color of the electrolyte might be caused by interaction of Cu ion and the by-product of ceria. The mechanical properties of the films were examined by nanoindentation, and reaction between ceria and electrolyte presumably affect the mechanical properties of electrodeposited copper films. We also examined their crystal structures and optical properties by X-ray diffraction (XRD) and UV-Vis spectroscopy.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집
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• pp.172-176
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• 2002

This paper describes a MEMS-based micro-fluxgate magnetic sensing element using Ni$\_$0.8/Fe$\_$0.2/ film formed by electroplating. The micro-fluxgate magnetic sensor composed of a thin film magnetic core and micro-structured solenoids for the pick-up and the excitation coils, is developed by using MEMS technologies in order to take advantage of low-cost, small size and lower power consumption in the fabrication. A copper with 20um width and 3um thickness is electroplated on Cr(300${\AA}$)/Au(1500${\AA}$) films for the pick-up(42turn) and the excitation(24turn) coils. In order to improve the sensitivity of the sensing element, we designed the magnetic core into a rectangular-ring shape to reduce the magnetic flux leakage. An electroplated permalloy film with the thickness of 3 $\mu\textrm{m}$ is obtained under 2000Gauss to induce magnetic anisotropy. The magnetic core has the high DC effective permeability of ∼1,100 and coercive field of -0.1Oe. The fabricated sensing element using rectangular-ring shaped magnetic film has the sensitivity of about 150V/T at the excitation frequency of 2MHz and the excitation voltage of 4.4Vp-p. The power consumption is estimated to be 50mW.

• 대한환경공학회지
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• 제29권12호
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• pp.1381-1389
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• 2007

중금속 폐수는 다양한 유독성 화합물과 함께 배출되므로 상수원, 토양, 지하수 등의 환경에 악영향을 야기 시킬 수 있다. 이러한 고농도의 복합중금속과 시안착염을 포함한 도금폐수 처리 시 일반적으로 잘 알려진 알카리염소법에 의한($1^{st}$ Oxidation: pH 10, reaction time 30 min, ORP 350 mV, $2^{nd}$ Oxidation: ORP 650 mV) 시안의 잔류농도에 대한 제거효율은 유입수의 시안농도 374 mg/L에 비해 처리 후 잔류시안농도는 3.74 mg/L로써 그 제거효율이 99%로써 상당히 높았으나 수질환경보전법상 수질배출허용기준(나 지역) 1 mg/L 이하에 만족하기 위해서는 2차, 3차 등의 고도처리가 요구됨을 알 수 있었고, 이에 아연백법 및 공침처리공정(reaction time: 30 min, pH: 8.0, rpm: 240)을 적용하여 용해되어 잔류하는 시안착염을 불용성염으로 침전시켜 처리한 결과 잔류시안농도가 1.0 mg/L 이하의 만족할 만한 결과를 있었다. 크롬의 처리는 6가 크롬을 3가 크롬으로 환원(pH: 2.0 max, ORP: 250 mV)시킨 후, 수산화물로 처리(pH: 9.5)시 무난히 99%의 최대 제거효율을 얻을 수 있었다. 폐수 중 나머지 동(Cu)과 니켈(Ni)처리는 황화물 응집침전법을 적용한 결과 최적 pH는 $9.0\sim10.0$에서 $Na_2S$의 최적주입량이 Cu의 경우 0.5 mol에서 99.1%, Ni의 경우 3.0 mol에서 99.0% 이상 제거할 수 있었다. 즉 중금속 복합폐수 중 시안착염은 알카리 염소산화처리법만으로는 수질환경보전법의 규제치 이하로 처리가 불가능 하였고 아연백법 및 공침공정을 같이 적용한 결과 규제치 이하로 처리가 가능하다는 것을 현장 확인할 수 있었다.