• Electrical & Electronic Materials
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• 제9권6호
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• pp.542-550
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• 1996

ZnO-based ceramic varistors containing NiO range 0.5 mol% to 4.0 mol% were fabricated by standard ceramic techniques. The influence of NiO on the microstructure and electrical behavior of ZnO varistor was investigated. As the content of NiO additive increases, average grain size decreased from 16.5.mu.m to 13.2.mu.m, and the amount of NiO existing in the grain interior and grain boundary region was approximately equal. NiO acted as an acceptor which decreases donor concentration due to the increase of Zn vacancy in the grain, and as a driver which migrates Zn interstitial in the depletion region toward the interface of grain boundary, which resulted in the decrease of interface state density. As a result, increasing the content of NiO additive, barrier height, nonlinear exponent, and varistor voltage decreased, and leakage current increased. Wholly, the physical and electrical properties of the ZnO varistor can be said to be affected by the NiO additive.

• Journal of Surface Science and Engineering
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• 제52권4호
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• pp.187-193
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• 2019

Electroless Ni-P coatings are widely used in the chemical, mechanical, and electronic industries because of their excellent wear and abrasion resistance. In this study, the effect of $TiO_2$ particles of composite coating was investigated. To improve the corrosion resistance, electroless $Ni-P-TiO_2$composite coating was studied by varying the $TiO_2$ content. The morphology and phase structure of $Ni-P-TiO_2$ composite coatings were analyzed by scanning electron microscopy(SEM), X-ray diffractometry(XRD) and X-ray photoelectron spectroscopy(XPS). The result showed that $Ni-P-TiO_2$composite coating is composed of Ni, P, Ti and O. It exhibits an amorphous structure, high hardness and good corrosion resistance to the substrate. $Ni-P-TiO_2$ composite coatings have higher open circuit potential than that of the substrate, which obtained at $TiO_2$ content of 5.0 g/L optimal integrated properties.

• Journal of Hydrogen and New Energy
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• 제35권2호
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• pp.185-194
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• 2024

Fe-Ni nanocatalysts loaded on carbon black were prepared via spontaneous reduction reaction of iron (II) acetylacetonate and nickel (II) acetylacetonate in dry process. Their morphology and elemental analysis were characterized by scanning electron microscopy, transmission electron microscopy (TEM), and energy dispersive X-ray analyzer. The loading weight of the nanocatalysts was measured by thermogravimetric analyze and the surface area was measured by BET analysis. TEM observation showed that Fe and Ni nanoparticles was well dispersed on the carbon black and their average particle size was 4.82 nm. The loading weight of Fe-Ni nanocatalysts on the carbon black was 6.83-7.32 wt%, and the value increased with increasing iron (II) acetylacetonate content. As the Fe-Ni loading weight increased, the specific surface area decreased significantly by more than 50%, because Fe-Ni nanoparticles block the micropores of carbon black. I-V characteristics showed that water electrolysis performance increased with increasing Ni nanocatalyst content.

• Journal of Hydrogen and New Energy
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• 제25권5호
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• pp.459-467
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• 2014

The catalytic steam reforming of toluene, a major component of biomass tar, was studied using several catalysts at various temperatures $400-800^{\circ}C$, kind of metal, and metal loading content. Ru and K promoted Ni-base catalyst were prepared, and used for steam reforming of toluene with steam/toluene molar ratio of 25. Concentration of toluene in reactant flow is $30g/Nm^3$ that is usual content of tar from biomass gasifier. The result from experiments showed that $H_2$ content in product gas and toluene conversion increased with temperature. Where in high temperature range, CO and $CO_2$ content in product gas were affected mainly by Boudouard reaction. Ni/Ru-K(3wt%)/$Al_2O_3$ catalyst showed best performance on steam reforming of toluene than used catalysts in this study at whole temperature. Catalysts have been characterized by XRD, TG. XRD analysis displayed that Ni particle size on Ni/Ru-K (3wt%)/$Al_2O_3$ catalyst was 29.4nm. Activation energy of Ni/Ru-K (3wt%)/$Al_2O_3$ catalyst was calculated 36.8kJ/mol by Arrhenius plot.

• Transactions on Electrical and Electronic Materials
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• 제12권1호
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• pp.24-27
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• 2011

Effect of substitution of Mn for Ni on transformation behavior, shape memory characteristics and superelasticity of Ti45Ni-5Cu alloy has been investigated by means of electrical resistivity measurements, X-ray diffraction, thermal cycling tests under constant load and tensile tests. The one-stage B2-B19' transformation occurred when Mn content was 0.5 at%, above which the two-stage B2-B19-B19' transformation occurred. A temperature range where the B19 martensite exists was expanded with increasing Mn content because decreasing rate of Ms (60 K / % Mn) was larger than that of Ms' (40 K / % Mn). Ti-(45-x)Ni-5Cu-xMn alloys were deformed in plastic manner with a fracture strain of 60 % ~ 32 % depending on Mn content. Clear superelasticity was found in fully annealed Ti-(45-x)Ni-5Cu-xMn alloys with Mn content more than 1.0 at%, which was ascribe to a solid solution hardening by substitution of Mn for Ni.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.441-443
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• 2005

According as CCFL(Cold Cathode Fluorescent lamp) of light source in Backlight unit for Note PC (Personal computer) is presently needed to low power consumption and long life time, the development focus of CCFL is going on the discharge gas, phosphor and electrode material. First of all, discharge voltage characteristic of CCFL is closely connected with electrode material For low discharge voltage, the characteristic of electrode material is needed to low work function, low sputtering ratio and superior manufacturing property. We developed new CCFL with Nb/Ni Clad electrode superior to conventional CCFL. Because Nb/Ni Clad electrode with Ni material and Nb material, the electrical characteristic is superior to other electrode materials. The electrode of Nb/Ni Clad is composed that Ni of outside material has superior manufacturing property and Nb of inside material has low work function. Nb/Ni Clad of new electrode material is made by process of Rolling mill at high pressure and heat treatment. We compared electrical characteristic of Nb/Ni clad electrode with conventional Mo electrode by measurement. Mo electrode and Nb/Ni Clad electrode of cup type with diameter 1.1 mm and length 3.0mm are used to this experiment. Material content of Mo electrode is Mo 100%. But, Nb/Ni Clad electrode is composed by content of Nb 40% and Ni 60%. The result of comparison measurement between new CCFL with Nb/Ni Clad electrode and conventional CCFL was appeared that CCFL with Nb/Ni Clad electrode had superior characteristic than conventional CCFL. As a result of experiment, we completed Note PC with low power consumption and long life time by application of new CCFL with Nb/Ni Clad electrode.

• Journal of the Korean Magnetics Society
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• 제6권6호
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• pp.382-387
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• 1996

The characteristics of the complex permeability of ${(Ni_{x}Cu_{0.2}Zn_{0.8-x}O)}_{1-w}{(Fe_{2}O_{3})}_{1+w}$ with various Ni and $Co_{3}O_{4}$ contents were investigated in this work. It is found that the NiCuZn ferrites with $x{\geq}0.6$ have a relatively small peak width of the imaginary part of permeability $\mu$". The resonance frequency is increased as Ni content becomes higher, where the loss is low. The $\mu$" value decreases with increasing FezO, deficiency, but the resonance frequency($f_{\mu"max}$) is only slightly affected by $Fe_{2}O_{3}$ deficiency. In case of $Co_{3}O_{4}$ addition to the NiCuZn ferrites, the $f_{\mu"max}$ increases since the initial permeability decreases with the amount of $Co_{3}O_{4}$. It is concluded that the Ni content in the NiCuZn ferrite is a dominant factor for the total loss of these spinel ferrites.

• The Korean Journal of Ceramics
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• 제2권3호
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• pp.162-166
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• 1996

The effects of NiO addition on the microstructure and microwave dielectric properties of ($Zr_{08}Sn_{02}$)$TiO_4$ (ZST) were investigated. With the NiO addition, a higher density of ZST ceramics than 95% of the theoretical values has been obtained in the sintering temperature range of 1400 to 150$0^{\circ}C$. Energy dispersive X-ray spectrometry (EDS) analysis of sintered specimen shows the presence of second phase at grain boundaries, which is considered to be $NiTiO_3$. Dielectric constant of the specimen is found to increase linearly with density. Q-values and TC$_r$ decrease with increasing NiO content. The variation of dielectric properties with NiO content is discussed in terms of the second phase. The ZST ceramics with 0.25 wt% NiO showed ${\varepsilon}_{\gamma}$=38, Q=7000 at GHz and TC$\gamma$=-0.5 ppm/$^{\circ}C$, comparable with the values obtained by the previous investigations.

• Journal of the Korean Society for Heat Treatment
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• 제22권2호
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• pp.101-107
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• 2009

Effect of isochronic aging on transformation behavior of Ti-50.85at%Ni alloy were investigated by differential scanning calorimeter (DSC). The martensitic transformation temperature increases with increasing annealing temperature until reaching a maximum, and then decreases with further increasing annealing temperature. This can be rationalized by interaction between the distribution of $Ti_3Ni_4$ precipitates and Ni content in the matrix. The R-phase transformation temperature increases with increasing annealing temperature until reaching a maximum, and then decreases with a further increase of annealing temperature. This is attributed to the change of Ni content in the matrix caused by precipitation of $Ti_3Ni_4$. The occurrence of the multiple-stage martensitic and R-phase transformation is attributed to precipitation-induced inhomogeneity of the matrix, both in terms of composition and of internal stress fields.

• Journal of Ceramic Processing Research
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• 제21권2호
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• pp.148-156
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• 2020

We investigated NiFe2O4/Ce0.9Gd0.1O1.95 (GDC) composites as oxygen carrier materials for chemical looping hydrogen production (CLHP). CLHP is a promising technology to simultaneously capture carbon dioxide and produce hydrogen from fossil fuels. We found that increasing GDC content increased the amount of the hydrogen production of NiFe2O4/GDC composites. Moreover, the oxygen transfer rate for the re-dox reaction increased significantly with increasing GDC content. GDC may affect the reaction kinetics of NiFe2O4/GDC composites. The finely dispersed GDC particles on the surface of NiFe2O4 can increase the surface adsorption of reaction gases due to the oxygen vacancies on the surface of GDC, and enlarge the active sites by suppressing the grain growth of NiFe2O4. The NiFe2O4/15wt% GDC composite showed no significant degradation in the oxygen transfer capacity and reaction rate during several re-dox cycles. The calculated amount of hydrogen production for the NiFe2O4/15wt% GDC composite would be 2,702 L/day per unit mass (kg).