• 비파괴검사학회지
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• 제37권2호
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• pp.75-83
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• 2017

In this paper, we investigate the capacity of the lock-in infrared thermography technique for the evaluation of non-uniform top layers of a silicon carbide coating with a nickel based superalloy sample. The method utilized a multilayer heat transfer model to analyze the surface temperature response. The modelling of the sample was done in ANSYS. The sample consists of three layers, namely, the metal substrate, bond coat and top coat. A sinusoidal heating at different excitation frequencies was imposed upon the top layer of the sample according to the experimental procedures. The thermal response of the excited surface was recorded, and the phase angle image was computed by Fourier transform using the image processing software, MATLAB and Thermofit Pro. The correlation between the coating thickness and phase angle was established for each excitation frequency. The most appropriate excitation frequency was found to be 0.05 Hz. The method demonstrated potential in the evaluation of coating thickness and it was successfully applied to measure the non-uniform top layers ranging from 0.05 mm to 1 mm with an accuracy of 0.000002 mm to 0.045 mm.

• 한국분말재료학회지
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• 제24권2호
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• pp.87-95
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• 2017

Lithium silicate, a lithium-ion conducting ceramic, is coated on a layer-structured lithium nickel manganese oxide ($LiNi_{0.7}Mn_{0.3}O_2$). Residual lithium compounds ($Li_2CO_3$ and LiOH) on the surface of the cathode material and $SiO_2$ derived from tetraethylorthosilicate are used as lithium and silicon sources, respectively. Powder X-ray diffraction and scanning electron microscopy with energy-dispersive spectroscopy analyses show that lithium silicate is coated uniformly on the cathode particles. Charge and discharge tests of the samples show that the coating can enhance the rate capability and cycle life performance. The improvements are attributed to the reduced interfacial resistance originating from suppression of solid-electrolyte interface (SEI) formation and dissolution of Ni and Mn due to the coating. An X-ray photoelectron spectroscopy study of the cycled electrodes shows that nickel oxide and manganese oxide particles are formed on the surface of the electrode and that greater decomposition of the electrolyte occurs for the bare sample, which confirms the assumption that SEI formation and Ni and Mn dissolution can be reduced using the coating process.

• 한국표면공학회지
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• 제40권2호
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• pp.63-69
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• 2007

Ni-SiC composite coating layers were formed using two kinds of SiC nano-particles by DC electrodeposition in a nickel sulfamate bath containing SiC particles. The effect of stirring rate and SiC particle type on the microstructure and properties of Ni-SiC composite coating layers were investigated. Results revealed that the trend of deposition rate is closely related to the codeposition of SiC and the deposition rate. or nickel, and the codeposition behavior of SiC can be explained by using hydrodynamic effect due to stirring. The average roughness and friction coefficient are closely related to the codeposition of SiC and SiC particle size. It was found that the Victors microhardness of the composite coating layers increased with increasing codeposition of SiC. The composite coating layers containing smaller SiC particle showed higher hardness. This can be explained by using the strengthening mechanism resulting from dispersion hardening. Anti-wear property of the composite coating layers formed using 130 nm-sized SiC nano-particles has been improved by 2,300% compared with pure electroplated-nickel layer.

• 한국태양에너지학회 논문집
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• 제33권3호
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• pp.27-35
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• 2013

One of the most important factors that have a large influence on performance of the solar water heater system is performance of the solar collector, more detailedly, coating technology on the surface of the solar collector, which can provide high solar absorptance and low emittance. The core of the coating technology is to coat solar selective surfaces. In this study, various performance experiments are carried out using $Cr_2(SO_4)_3{\cdot}15H_2O$ coating technology. Here, IGBT(Insulated Gate Bipolar Transistor) of 5000A-15V was used as the surface processing rectifier which can stably output power and also can control voltage and current. The plating solution mainly contains black chrome$^{+3}$ concentration, H-y Conductivity, N-u Complex, NF Additive and NC-2 Wetter. Before applying the black chrome coating on the copper plate, optimal conditions are provided by using various preprocessing methods such as removal of fat, activation, electrolytic polishing, nickel strike, copper sulfate plating and bright neckel plating, and then the automatic continuous coating experiment are performed according to plating time and cathode current density. In the experiment, after the removal of fat, chemical polishing, nickel strike and activation processes as the preprocessing methods, the black chrome coating was performed in a plate solution temperature of $28^{\circ}C$ and a cathode current density of $18A/cm^2$ for 90 seconds. The thickness of chrome and nickel on the coated plate is $0.389{\mu}m$, $159{\mu}m$ respectively. As a result of the coating experiment, it showed the most excellent performance having a high solar absorptance of 98% and a low emittance of $5{\pm}1%$ when the black chrome surface had a thickness of $0.398{\mu}m$.

• 한국인터넷방송통신학회논문지
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• 제18권6호
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• pp.107-112
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• 2018

콘포멀 스프레이 코팅으로 형성한 EMI 차단막으로 차폐효과(SE)를 얼마나 개선할 수 있는지 연구하였다. 차단막을 형성하는데 사용한 재료는 도체 분말을 아크릴계 바인더에 혼합한 금속-레진 복합재료이며, 금속분말로는 은(Ag)과 니켈(Ni)을 비교하였다. 재료의 점도는 400 cPs와 100 cPs에서 차폐성능을 비교하였다. 차단막의 두께는, 은의 경우 20 um에서 50 um, 니켈의 경우 60 um에서 120 um로 만들어 비교하였다. 차폐효과의 측정은 동축형 표준 측정기를 이용하여 ASTM D4935 방법으로 수행하였다. 니켈 시료보다 은 시료의 차폐효과가 우수했다. 차폐효과는 차단막 두께와 비례해 증가하지만 35 um 이상에서 더 이상 증가하지 않는다는 사실도 관찰하였다. 가장 차폐효과가 좋은 경우는 35 um 두께 은 시료 차단막으로, 63 dB의 차폐효과가 측정되었다.

• Journal of Electrochemical Science and Technology
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• 제12권2호
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• pp.272-278
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• 2021

In this study, high nickel layered LiNi_0.8Co_0.1Mn_0.1O₂ cathode materials for lithium-ion batteries were modified by yttrium doping and poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) coating. The effects of yttrium doping and PEDOT:PSS coating on the structural and electrochemical properties of the LiNi_0.8Co_0.1Mn_0.1O₂ cathode material were investigated and compared. The substitution of nickel with an electrochemically inert yttrium was confirmed to be successful in stabilizing the layered structure framework. Moreover, coating the surfaces of the LiNi_0.8Co_0.1Mn_0.1O₂ particles with a conductive polymer, PEDOT:PSS, improved the capacity retention, thermal stability, and impedance of the cathode material by increasing its ionic and electric conductivities.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2006년도 춘계학술발표논문집
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• pp.184-187
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• 2006

Nickel was plated electrolessly on 304L stainless steel powder. To obtain uniform coating and dispension of powder, the bath was continuously agitated with magnetic stirrer. The various pH and bath temperatures were studied. The conditions were in the range of $pH4{\sim}10$ and $45{\sim}65^{\circ}C$, respectively. The coating morphologies were examined by SEM/EDS tests. The optimum condition was pH9 at $55^{\circ}C$.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1999년도 추계학술대회 논문집 - 한국공작기계학회
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• pp.287-292
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• 1999

This study is object to thermal analysis of continuous casting nickel-coated mold. A two-dimensional transient finite element model was developed to compute the temperature distribution and stress behavior for continuous casting nickel-coated mold. For thermal analysis using analysis result from FEM code. In other to thermal analysis of continuous casting nickel-coated mold, many variables such as casting speed, cooling condition, film coefficient, convection and load condition are considered.

• 한국표면공학회지
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• 제32권3호
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• pp.214-218
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• 1999

The effect of additives in nickel and copper electroplating were investigated for MEMS applications. Saccharin and gelatin were used as additives in nickel and copper electroplating bath respectively. The morphology and surface hardness of electroplated coating were investigated with additive concentration. Microstructures were fabricated with optimum conditions.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.365.2-365.2
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• 2014

Nickel sulfide (NiS) has been utilized in optoelectronic applications, such as transformation-toughening agent for materials used in semiconductor applications, catalysts, and cathodic materials in rechargeable lithium batteries. Recently, high quality nickel sulfide thin films have been explored using ALD/CVD technique. Suitable precursors are needed to deposit thin films of inorganic materials. However, nickel sulfide precursors available for ALD/CVD process are very limited to nickel complexes with dithiocarbamate and alkanethiolate ligands. Therefore, it is essential to prepare novel nickel sulfide suitable for ALD/CVD precesses. Herein we report on the synthesis and characterization of new nickel sulfide complex with designed aminothiolate ligand. Furthermore thin films of NiS have been prepared on silicon oxide substrates by spin coating nickel precursor 10 wt% in THF. The novel complex has been characterized by means of 1H-NMR, elemental analysis, thermogravimetric analysis (TGA), X-ray Diffraction (XRD) and scanning electron microscope (SEM).