• Journal of Technologic Dentistry
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• v.29 no.2
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• pp.213-223
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• 2007

The success of a porcelain fused to metal (PFM) restoration depends upon the quality of the porcelain-metal bond. The adhesion between metal substructure and dental porcelain is related to the diffusion of oxygen to the reaction layer formed on cast-metal surface during firing. The purposed of this investigation was to study the effects of gold based bonding agent on Ni-Cr alloy-ceramic adhesion between porcelain matrix, gold based bonding agent and metal substructure interface. gold based bonding agent have been applied as an intermediate layer between a metal substructure and a ceramic coating. gold based bonding agent(Aurofilm NP, Metalor, Swiss) was applied on Ni-Cr alloy surface by four method. Surfaces only air abraded with 110${\beta}\neq$ Al2O3 particles were used as control. metal ceramic adhesion was evaluated by a biaxial flexure test(N=5) and volume fraction of adherent porcelain was determined by SEM/EDS analysis. Result of this study suggest that the layering sequence of gold based bonding agent is very important and can improve porcelain adherence to PFM.

• Transactions of the Korean hydrogen and new energy society
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• v.21 no.2
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• pp.117-122
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• 2010

BCY($Ba(Ce_{0.9}Y_{0.1})O_{3-\delta}$) oxide, shows high protonic conductivity at high temperatures, and are referred to as hydrogen separation membrane. For high efficiency of hydrogen separation ($H_2$ flux and selectivity) and low fabrication cost, ultimate thin and dense BCY-Ni layer have to be coated on a porous substrate such as $ZrO_2$. Aerosol depostion (AD) process is a novel technique to grow ceramic film with high density and nano-crystal structure at room-temperature, and would be applied to the fabrication process of AD integration ceramic layer effectively. XRD and SEM measurements were conducted in order to analyze the characteristics of BCY-Ni membrane fabricated by AD process.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.8
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• pp.508-513
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• 2017

Ultraviolet (UV) photodetectors are used in various industries and fields of research, including optical communication, flame sensing, missile plume detection, astronomical studies, biological sensors, and environmental research. However, general UV detectors that employ Schottky junction diodes and p-n junctions have high fabrication cost and low quantum efficiency. In this study, we investigated the characteristics of materials used to manufacture UV photodetectors in a low-cost solution process that requires easy fabrication of flexible substrates. We fabricated p-type NiO and n-type ZnO substrates with wide band gap by the sol-gel method and compared the characteristics of substrates prepared under different spin-coating and heat-treatment conditions.

• Journal of the Korean institute of surface engineering
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• v.26 no.6
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• pp.291-298
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• 1993

In order to substitute for porous nickel anode in Molten Carbonate Fuel Cell(MCFC), porous cermet elec-trode was fabricated with Ni and Ni-P coated ceramic powder. Ni and Ni-P were coated by electroless plat-ing method in the nickel solution containing of hydrazine and sodium hypophosphate as a reducing agent. The plating solution was stirred by air and mechanical agitator. Ultrasonic irradiation was applied to the plating bath to improved the effect of agitation and coating speed. Electorde was formed by pressing method and doc-tor blade method followed by sinterd at$ 800^{\circ}C$ for 6 hours in H2 environment. Anode performance test carried out by potentiodynamic polarization technique in the MCFC operating condition and 154-161mA/$\textrm{cm}^2$ as ob-tained as a anode current density at the+100mV overpotential.

• Journal of the Korean institute of surface engineering
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• v.47 no.6
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• pp.323-329
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• 2014

Effects of sealant and sealing procedure on corrosion resistance of high velocity oxy-fuel (HVOF) sprayed coatings were studied. HVOF-sprayed CrC-20NiCr coatings were sealed using three commercial sealants based on phenolics and epoxy. Penetration depth of sealants, measured by fluorescent microscope technique, was between $19{\mu}m$ and $340{\mu}m$ depending on sealant, sealing condition or sealing procedure. It was found that sealing on rotation status was more effective than that on stationary specimen due to the Coriolis effect of fluid in pores of the coating. From the CASS results, corrosion resistance of properly sealed CrC-20NiCr coatings was equal to that of hexa-valent chromium plating.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.6_2
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• pp.1037-1045
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• 2022

In this study, nanoscale Al₂O3 ceramic particles were used due its exceptionally high hardness characteristics, chemical stability, and wear resistance properties. These nanoparticles will be used to investigate the optimal process conditions for the electro co-deposition of the Ni-Al₂O₃ composite coatings. A Watts bath electrolytic solution of a controlled composition along with a fixed agitation speed was used for this study. Whereas the current density, the pH value, temperature and concentration of the nano Al₂O₃ particles of the electrolyte were designated as the manipulative variables. The experimental design method was based on the orthogonal array to find the optimum processing parameters for the electro co-deposition of Ni-Al₂O₃ composite coatings. The result of confirmation experimental based on the optimal processing condition through the analysis of variance ; EDX analysis found that the ratio of alumina increased to 8.65 wt.% and subsequently the overall hardness increased to 983 Hv. Specially, alumina were evenly distributed on Nickel matrix and particles were embedded more firmly and finely in Nickel matrix.

• Transactions of the Korean hydrogen and new energy society
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• v.21 no.6
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• pp.533-539
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• 2010

Ni-YSZ supported button cells were prepared by spray-coating YSZ and screen-printing YSZ-LSM powder as an electrolyte and oxygen electrode on Ni-YSZ cermet disks. In order to identify the polarization loss mechanism in high temperature electrolysis current-voltage characteristics coupled with electrochemical impedance spectroscopy were investigated as a function of temperature, current load, and the humidity. The effects of the different current collectors of platinum and silver for oxygen electrodes were compared. With Ag current collector two polarization losses were distinguished. The high frequency component was attributed to the Ni-YSZ cermet which was less susceptible to temperature variation but increasing in loss with humidity. The lower frequency component was attributed to the LSM electrode. Platinum current collector led to a much lower polarization loss.

• Journal of the Korean Ceramic Society
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• v.41 no.3
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• pp.229-234
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• 2004

In this study, we proposed new forming process for a porous ceramic body with unique pore structure. h tubular-type porous NiO-YSZ body with radially aligned pore channels was prepared by freeze-drying of aqueous slurry. A NiO-YSZ slurry was poured into the mold, which was designed to control the crystallization direction of the ice, followed by freezing. Thereafter the ice was sublimated at a reduced pressure. SEM observations revealed that the NiO-YSZ porous body showed aligned large pore channels parallel to the ice growth direction, and fine pores are formed around the outer surface of the tube. It was considered that the difference in the ice growth rate during the freezing process resulted in such a characteristic microstructure. Bilayer consisting of dense thin electrolyte film of YSZ onto the tubular type porous body has been successfully fabricated using a slurry-coating process followed by co-firing. It was regarded that the obtained bilayer structure is suitable for constructing electrode-support type electrochemical devices such as solid oxide fuel cells.

• Journal of Powder Materials
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• v.28 no.3
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• pp.201-207
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• 2021

Ni-Cr-Al metal-foam-supported catalysts for steam methane reforming (SMR) are manufactured by applying a catalytic Ni/Al₂O₃ sol-gel coating to powder alloyed metallic foam. The structure, microstructure, mechanical stability, and hydrogen yield efficiency of the obtained catalysts are evaluated. The structural and microstructural characteristics show that the catalyst is well coated on the open-pore Ni-Cr-Al foam without cracks or spallation. The measured compressive yield strengths are 2-3 MPa at room temperature and 1.5-2.2 MPa at 750℃ regardless of sample size. The specimens exhibit a weight loss of up to 9-10% at elevated temperature owing to the spallation of the Ni/Al₂O₃ catalyst. However, the metal-foam-supported catalyst appears to have higher mechanical stability than ceramic pellet catalysts. In SMR simulations tests, a methane conversion ratio of up to 96% is obtained with a high hydrogen yield efficiency of 82%.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.4
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• pp.475-480
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• 2010

The thermal barrier coating of a gas turbine blade was degraded by isothermal heating in a furnace and by varying the exposure time and temperature. Then, a micro-Vickers hardness test was conducted on the cross section of the bond coat and Ni-based superalloy substrate. Further, the thickness of TGO(Thermally Grown Oxide) was measured by using an image analyzer, and the changes in the microstructure and element contents in the coating were analyzed by using an optical microscope and by performing SEM-EDX analysis. No significant change was observed in the Vickers hardness of the bond coat when the coated specimen was degraded at a high temperature; delamination was observed between the top coat and the bond coat when the coating was degraded for 50 h at a temperature $1,151^{\circ}C$.