• Journal of the Korean Chemical Society
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• v.57 no.3
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• pp.311-315
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• 2013

The geometry structures of hexa-coordinated [NiLX]X complexes ($X=Cl^-,\;Br^-,\;I^-$) {L = 8,9,18,19-tetrahydro-7H,17H-dibenzo[f,o] [1,5,9,13]dioxadiaza cyclohexadecine-8,18-diol} are optimized by density functional theory (DFT) using B3LYP/LANL2DZ. The calculated geometric parameters are in good agreement with the corresponding experimental values. Calculation results about these complexes show that dipole moment decreases, and the energy levels of HOMOs descend from iodo-complex to chloro-complex. The energy levels of HOMOs descend gently from iodo-complex to chloro-complex, while the energy levels of LUMOs in the present complexes are almost similar; therefore the energy gapes between HOMOs and LUMOs increased from iodo-complex to chloro-complex.

• Membrane Journal
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• v.16 no.1
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• pp.77-84
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• 2006

Transport mechanisms of nickel ion through a continuous electrodeionization (CEDI) were investigated in terms of electric properties of ion exchange textile (IET). The porous plug model and extended Nernst-Plank (N-P) equation were applied for the description of transport mechanism of nickel ion. The model revealed that the CEDI performance was mainly due to the induced current not accelerated mobility by IET. This study also suggested that optimal operating conditions are attained with minimized electroregeneration region.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.231-232
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• 2007

Nickel oxide thin films were deposited by the DC magnetron reactive sputtering process under the conditions such as various oxygen flow rates(0, 3, 6, 8, 10 sccm) with constant 33 sccm argon flow rate for the sputtering time of 40 second with the power of 0.3 kW. Sheet resistances were measured by the four point probes. In order to observe discharge voltage characteristics according to the oxygen flow rates, the sputtering processes were performed under the powers of 0.2kW and 0.3kW. The feasibility of the coating system for high quality ferromagnetic thin films was tested through the electromagnetic simulation and the thin film thickness measurement from the experiment. It was shown that a discharge voltage was decreased under the low power and low oxygen flow rate, since the oxygen was quickly saturated on nickel target surface. The sheet resistance was increased as oxygen flow rate increased. The film thickness deposited by the coating system for ferromagnetic target was improved approximately 10% in comparison with previous coating systems.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.05a
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• pp.279-282
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• 2005

Composites comprising various volume fractions of crystalline nickel and bulk amorphous (BA) were produced by means of electroless coating of nickel on BA powder of $Cu_{54}Ni_6Zr_{22}Ti_{18}$ and subsequent spark plasma sintering (SPS) of coated BA powder. The flow curves of composites at various temperatures in the supercooled liquid region were determined by the uniaxial compression test with various strain rates. During compression at $450^{\circ}C$ with $\dot{\varepsilon}=2\times10^{-3}$, the monolithic BA sample and crystalline-BA composites displayed the superplastic deformation with $\varepsilon>1.4$. At temperatures above $460^{\circ}C$, the stress-strain curve of the monolithic BA sample depicted a sharp peak stress and a fellowing stress drop due to cracking, while those of the crystalline-BA composites displayed work-hardening up to the imposed strain. FEM analysis indicated that a fairly homogeneous strain state prevailed throughout the composite, while a higher level of stress was obtained in a harder BA.

• Corrosion Science and Technology
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• v.20 no.5
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• pp.281-288
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• 2021

Due to advancement of the industry, operation of a device in a harsh environment is increasing. Especially, the marine environment contains Cl^- ions which causes localized corrosion such as pitting and crevice corrosion of stainless steel and various metals. In this study, electrochemical corrosion behaviors of austenitic stainless steel (STS 316L) and nickel alloy (Inconel 600) with different seawater concentrations (fresh water, seawater, mixed water) were investigated. The STS 316L and Inconel 600 were etched in 10% oxalic acid and composed of an austenitic phase. Results of Tafel analysis in seawater showed that STS 316L and Inconel 600 presented the highest corrosion current densities of 7.75 × 10^-4 mA/cm² and 1.11 × 10^-4 mA/cm² and the most negative pitting potentials of 0.94 V and 1.06 V, respectively. The maximum damage depths and surface damage ratio by pitting corrosion increased with chloride concentration. The STS 316L had higher PREN than Inconel 600. However, the surface damage and weight loss of Inconel 600 were superior to STS 316L. It was difficult to compare the pitting resistance of STS 316L based on Fe and Inconel 600 based on Ni with PREN simply.

• Nuclear Engineering and Technology
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• v.53 no.1
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• pp.304-313
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• 2021

Nickel base Alloy X-750, which is used as fastener parts in light-water reactor (LWR), has experienced many failures by environmentally assisted cracking (EAC). In order to improve the reliability of passive components for nuclear power plants (NPP's), it is necessary to study the failure mechanism and to predict crack growth behavior by developing a probabilistic failure model. In this study, The Bayesian inference was employed to reduce the uncertainties contained in EAC modeling parameters that have been established from experiments with Alloy X-750. Corrosion fatigue crack growth rate model (FCGR) was developed by fitting into Paris' Law of measured data from the several fatigue tests conducted either in constant load or constant ΔK mode. These parameters characterizing the corrosion fatigue crack growth behavior of X-750 were successfully updated to reduce the uncertainty in the model by using the Bayesian inference method. It is demonstrated that probabilistic failure models for passive components can be developed by updating a laboratory model with field-inspection data, when crack growth rates (CGRs) are low and multiple inspections can be made prior to the component failure.

• Applied Chemistry for Engineering
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• v.8 no.5
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• pp.742-748
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• 1997

Diamond films which have high hardness and thermal conductivity can be used to improve the performance of WC-Co as a cutting tool material. However, it is difficult to get such coatings of good uniformity and adhesiveness due to the surface characteristics of WC-Co. To get better coatings, some techniques, such as the surface treatment of substrate or the formation of interlayer between substrate and diamond film, have been tried. In the present work, the nickel interlayer is formed onto WC-Co by electroless Ni-P plating, which is introduced as a new method, and then diamond film is deposited on the interlayer. Formation and uniformity of three layers, i.e., substrate, electroless plate, and diamond film, and the adhesiveness of interlayers were studied. To investigate the effects of pretreatment on electroless plating, two different methods such as acid treatment and diamond powder treatment were used. The effects of heat treatment of the electroless plated surface on adhesiveness between the substrate and the interlayer were examined. It was found that as the temperature increases, the Ni crystals grow and then result in improved adhesiveness. Diamond film coatings of pure diamond phase were obtained at $800^{\circ}C$. It is concluded that the heat treated electroless Ni-P plating can be effectively used as a interlayer between WC-Co substrate and diamond film.

• Journal of Korean Society of Water and Wastewater
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• v.28 no.2
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• pp.207-215
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• 2014

Wastewater containing heavy metals such as copper (Cu) and nickel (Ni) is harmful to humans and the environment due to its high toxicity. Crystallization in a fluidized bed reactor (FBR) has recently received significant attention for heavy metal removal and recovery. It is necessary to find optimum reaction conditions to enhance crystallization efficacy. In this study, the effects of crystallization reagent and pH were investigated to maximize crystallization efficacy of Cu-S and Ni-S in a FBR. CaS and $Na_2S{\cdot}9H_2O$ were used as crystallization reagent, and pH were varied in the range of 1 to 7. Additionally, each optimum crystallization condition for Cu and Ni were sequentially employed in two FBRs for their selective removal from the mixture of Cu and Ni. As major results, the crystallization of Cu was most effective in the range of pH 1-2 for both CaS and $Na_2S{\cdot}9H_2O$ reagents. At pH 1, Cu was completely removed within five minutes. Ni showed a superior reactivity with S in $Na_2S{\cdot}9H_2O$ compared to that in CaS at pH 7. When applying each optimum crystallization condition sequentially, only Cu was firstly crystallized at pH 1 with CaS, and then, in the second FBR, the residual Ni was completely removed at pH 7 with $Na_2S{\cdot}9H_2O$. Each crystal recovered from two different FBRs was mainly composed of CuxSy and NiS, respectively. Our results revealed that Cu and Ni can be selectively recovered as reusable resources from the mixture by controlling pH and choosing crystallization reagent accordingly.

• Korean Chemical Engineering Research
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• v.48 no.6
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• pp.776-783
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• 2010

Co and Ni catalysts supported on $Al_2O_3$ for partial oxidation of methane producing hydrogen were synthesized using impregnation to incipient wetness. The activities of these catalysts for the partial oxidation of methane was investigated at 1 atm and $CH_4/O_2=2.0$ in the temperature range of $450{\sim}650^{\circ}C$. The reaction activity of $Ni/Al_2O_3$ and $Co/Al_2O_3$ catalysts with different loading was investigated. And the beneficial effects of Ni addition to $Co/Al_2O_3$ and the promotional effects of Ce and La addition to $Ni/Al_2O_3$ and $Co/Al_2O_3$ were investigated. These catalysts were characterized by XRD and SEM/EDX. Comparing catalyst loadings, 10 wt% Co and 10 wt% Ni were found to be optimal at the experimental conditions. The 10 wt% $Ni/Al_2O_3$ and 10 wt% $Co/Al_2O_3$ catalysts in partial oxidation of methane showed $CH_4$ conversions and CO selectivity close to the thermodynamic equilibrium levels, but showed lower $H_2$ selectivity than equilibrium level. The addition of Ni to $Co/Al_2O_3$ exhibited higher $H_2$ selectivity but beneficial effect was not observed in the $CH_4$ conversion. Addition of Ce to $Co/Al_2O_3$ and addition of La to $Ni/Al_2O_3$ a improved the $CH_4$ conversion level and $H_2$ selectivity.

• Journal of the Korean Ceramic Society
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• v.50 no.6
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• pp.510-517
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• 2013

In this study, the properties of blue inorganic nano-pigments with a spinel structure were systematically investigated. We report the preparation of a blue ceramic nano-pigment and the Co and Ni substitutional effects on the blue color. $MgAl_2O_4$ was selected as the crystalline host network for the synthesis of cobalt and nickel-based blue ceramic nano-pigments. Various compositions of $Co_xMg_{1-x}Al_2O_4$ and $Ni_xMg_{1-x}Al_2O_4$ ($0{\leq}x{\leq}1$) powders were prepared using apolymerized complex method. The obtained powder was preheated at $400^{\circ}C$ for 5 h and then calcined at $1000^{\circ}C$ for 5 h. XRD patterns of the (Co,Mg)$Al_2O_4$ and (Ni,Mg)$Al_2O_4$ samples showed a single phase of the spinel structure in all compositions. TEM results indicated nano-sized pigments for (Co,Mg)$Al_2O_4$ and (Ni,Mg)$Al_2O_4$ with a particle size ranging from 20 to 50 nm. The characteristics of the color tones of (Co,Mg)$Al_2O_4$ and (Ni,Mg)$Al_2O_4$ were analyzed by CIE $L^*a^*b^*$ measurements. In addition, the thermal stability and the binding characteristics of (Co,Mg)$Al_2O_4$, (Ni,Mg)$Al_2O_4$ are discussed in terms of the TG-DSC and FT-IR results, respectively.