• Korean Journal of Materials Research
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• v.21 no.6
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• pp.309-313
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• 2011

The power capacitors used as vehicle inverters must have a small size, high capacitance, high voltage, fast response and wide operating temperature. Our thin film capacitor was fabricated by alumina layers as a dielectric material and a metal electrode instead of a liquid electrolyte in an aluminum electrolytic capacitor. We analyzed the micro structures and the electrical properties of the thin film capacitors fabricated by nano-channel alumina and metal electrodes. The metal electrode was filled into the alumina nano-channel by electroless nickel plating with polyethylene glycol and a palladium catalyst. The spherical metals were formed inside the alumina nano pores. The breakdown voltage and leakage current increased by the chemical reaction of the alumina layer and $PdCl_2$ solution. The thickness of the electroless plated nickel layer was 300 nm. We observed the nano pores in the interface between the alumina layer and the metal electrode. The alumina capacitors with nickel electrodes had a capacitance density of 100 $nF/cm^2$, dielectric loss of 0.01, breakdown voltage of 0.7MV/cm and leakage current of $10^4{\mu}A$.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.05a
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• pp.118-121
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• 2007

Bulk metallic glass (BMG)/crystalline composites comprising a copper based BMG alloy and crystalline nickel were produced by means of eloctroless plating of nickel on $Cu_{54}Zr_{22}Ti_{18}Ni_6$ BMG powder and subsequent consolidation using spark plasma sintering. The plastic deformation behavior of BMG/crystalline composites was examined by uniaxial compression test at various temperatures in the supercooled liquid region (SLR) of the BMG alloy. The evolution of strain states during uniaxial compression was tackled by microstructure observations. Deformation temperature played an important role in the deformation behavior of BMG/crystalline composites, which was attributed to a strong temperature dependence of the flow stress of the BMG alloy in the SLR. BMG/crystalline composites deformed homogenously in the temperature range where the flow stress of the BMG alloy was close to that of crystalline nickel. In contrast, inhomogeneous deformation was observed in the temperature range where the flow stress of the BMG alloy largely differs from that of crystalline nickel.

• Journal of the Korean Magnetics Society
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• v.22 no.2
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• pp.42-44
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• 2012

We have studied a means to control the composition of nickel-iron thin films. By changing current and voltage applied to a electroplating electrolyte we could manipulate the relative concentration of nickel and iron in the thin films, which caused variations of coercivity, squareness, and saturation magnetic field. As we increase the content of iron in the thin films by using potentiostatic and galvanostatic plating, the grain size was increased and the coercivity was reduced.

• Environmental Engineering Research
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• v.12 no.1
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• pp.16-20
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• 2007

Toxicity of metal plating wastewater was evaluated by using acute toxicity tests on Daphnia magna. To identify toxicants of metal plating wastewater, several manipulations such as solid phase extraction (SPE), ion exchange and graduated pH adjustment were used. The SPE test had no significant effect on baseline toxicity, suggesting absence of toxic non-polar organics in metal plating wastewater. However, anion exchange largely decreased the baseline toxicity by 88%, indicating the causative toxicants were inorganic anions. Considering high concentration of chromium in metal plating wastewater, it is thought the anion is Cr(VI) species. Graduated pH test showing independence of the toxicity on pH change strongly supports this assumption. However, as revealed by toxicity confirmation experiment, the initial toxicity of metal plating wastewater (24-h TU=435) was not explained only by Cr(VI) (24-h TU = 725 at $280\;mg\;L^{-1}$). Addition of nickel($29.5\;mg\;L^{-1}$) and copper ($26.5\;mg\;L^{-1}$) largely decreased the chromium toxicity up to 417 TU, indicating antagonistic interaction between heavy metals. This heavy metal interaction was successfully predicted by an equation of 24-h $TU\;=\;3.67\;{\times}\;\ln([Cu]\;+\;[Ni])\;+\;79.44$ at a fixed concentration of chromium.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.7
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• pp.273-279
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• 2016

This paper deals with a control system with a concentration sensor for Ni-W alloy plating solutions. The printed circuit board market has increased with the development of the electronics industry. Gold consumption has also increased dramatically. Various studies of composite plating solutions have been conducted because of the expense of gold. In comparison, the development of sensors capable of measuring a composite plating solution in real-time is still insufficient. Furthermore, there are few systems that can measure and control the concentration of the solution precisely. This study developed a sensor and system to control the concentration of composite plating solution accurately. The sensors were developed based on a spectrophotometric method and a feedback control method was applied in this system.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.5
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• pp.430-437
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• 2004

This paper is intended as an investigation of study on the thermal and electrical characteristics of the carbon heating element. In this experimentation, the electric material used is the crystalline graphite a kind of natural graphite. The bentonite is used to solidify the heating element and the vacuum furnace is used for sintering it. It is noted that the natural drying time should be at least 58 hours. The plating of the electric pole with the electroless nickel showed the lowest contact resistance among others. The resistance shows linear variation with regard to length. For the insulation and resolution, the glaze coating is best with 80% of water content. The temperature rising characteristic of the heating element is better than sheath heater saving 43% of rising time. The correlation equation for temperature was obtained with the electric power.

• Textile Coloration and Finishing
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• v.10 no.2
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• pp.8-17
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• 1998

In this study we have examined electroless chemical plating on the plasma grafted poly [ethylene terephathalate］(PET) fabric in order to improve the interfacial adhesion between metal and fiber. The vapour phase of acrylic acid introduced on the PET surface and the graft polymerization was carried out by using cold plasma, resulting in the grafting yield of 0.8-1.3 wt％. The carboxyl group of the plasma grafted was identified by FT-IR-ATR spectra. The Interfacial adhesion was related to the carboxyl group. After electroless chemical plating of nickel, it showed that the more the carboxyl, the better the interfacial adhesion. Comparing to the untreated, the plasma grafted fabric showed fairly good interfacial adhesion(5B grade, ASTM D3359) . The shielding effect of electromagnetic wave showed 95dB. The shielding effect depends on the fabric structure, the surface structure, and the cross sectional shape of fibers. The dense fabric structure, the etched surface like a microcrater, and the trigonal cross sectional shape were prefered.

• Journal of Surface Science and Engineering
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• v.32 no.2
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• pp.172-181
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• 1999

The effect of the DMAB concentration, temperature, deposition time, and stabilizer concentration on the precipitation reaction of the electroless nickel plating using dimethylamine borane (DMAB) as reducing agent was investigated to by the weight gain and electrochemical method. The deposition rate was dependent with DMAB concentration. The polarization resistance of the precipitation reaction was reduced with DMAB concentration. The precipitation reaction rate of Ni-B deposits was controlled by the oxidation rate of DMAB as the source of electron. The boron content of the deposit was constant at about 5.5wt%, even when DMAB concentration in the solution was increased. The effect of temperature and stabilizer ($Pb(NO_3)_2$) concentration on deposition rate was shown to have co-dependent behaviors.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2011.05a
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• pp.188-188
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• 2011

고급스러운 표면의 제품을 선호하는 사람들이 늘어나게 되면서 rough한 표면을 구현하여 광택을 줄인 사틴 니켈 도금 층에 대한 수요가 증가하고 있다. 현재 사틴 니켈 도금 용액에 사용되고 있는 사틴 효과를 구현하기 위한 첨가제 종류 중 에멀젼 타입의 첨가제는 시간이 경과함에 따라서 첨가제 입자들의 뭉침 현상이 발생하게 되고 이로 인하여 도금 용액의 수명이 9시간 정도로 짧게 나타난다. 이에 본 연구에서는 도금 용액 수명을 연장하기 위하여 사틴 첨가제의 재 첨가에 따른 표면 특성을 관찰하였다. 건욕 후 9시간마다 재 첨가할 경우 사틴 효과가 유지되어 용액 수명이 연장 된 것으로 판단된다.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.604-605
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• 2006

Recently the Marangoni convention is supposed to be an important phenomenon that significantly affects the solidification. For understanding the Marangoni convection mechanism, visualizing the convention phenomenon of molten tin with ultrasonic has been conducted. This paper reports developing a tracer material of micro metal balloon that is used in the molten system. We have succeeded in coating the surface of Shirasu-ballons with nickel by plating process. The obtained metal balloon is spherical and some characterizations were conducted.