• Journal of the Korean Magnetics Society
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• v.5 no.2
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• pp.134-139
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• 1995

We produced $(Co_{93}Cr_{7})-P-Ni$ thin films for longitudinal magnetic recording media using OC magnetron sputtering system The variation of magnetic properties of $(Co_{93}Cr_{7})-P-Ni$ pseudo-ternary system with the composition was examined. We obtained the coercivity up to 1500 Oe. The coercivity iocrease could be ascribed to in-plane anisotropy enhaocement, grain size decrease, magnetic decoupling between particles. TEM micrographs showed that the grains were well-decoupled by the addition of phosphorous.

• Journal of the Korean institute of surface engineering
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• v.48 no.6
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• pp.260-268
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• 2015

The thermal barrier coating (TBC) for inner wall of liquid-fuel rocket combustor consists of NiCrAlY as bonding layer and $ZrO_2$ as a top layer. In most case, the plasma spray coating is used for TBC process and this process has inherent possibility of cracking due to large difference in thermal expansion coefficients among bonding layer, top layer and metal substrate. In this paper, we suggest crack-free TBC process by using a precise electrodeposition technique. Electrodeposited Ni-P/Cr double layer has similar thermal expansion coefficient to the Cu alloy substrate resulting in superior thermal barrier performance and high temperature oxidation resistance. We studied the effects of phosphorous concentrations (2.12 wt%, 6.97 wt%, and 10.53 wt%) on the annealing behavior ($750^{\circ}C$) of Ni-P samples and Cr double layered electrodeposits. Annealing temperature was simulated by combustion test condition. Also, we conducted SEM/EDS and XRD analysis for Ni-P/Cr samples. The results showed that the band layers between Ni-P and Cr are Ni and Cr, and has no formed with heat treatment. These band layers were solid solution of Cr and Ni which is formed by interdiffusion of both alloy elements. In addition, the P was not found in it. The thickness of band layer was increased with increasing annealing time. We expected that the band layer can improve the adhesion between Cr and Ni-P.

• Journal of the Microelectronics and Packaging Society
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• v.26 no.4
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• pp.133-140
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• 2019

The effects of thermal cycle conditions on the bonding strength and crack propagation behaviors in electroplated Cr/electroplated Ni-P coatings were systematically evaluated. 1^st heat treatment was performed at 500℃ for 3 hours after electroplating Ni-P, and then, 2^nd heat treatment was performed at 750℃ for 6 hours after electroplating Cr. The measured bonding strength by ASTM C633 were around 25.6 MPa before thermal cycling, while it increased to 47.6 MPa, after 1,000 cycles. Increasing thermal cycles led to dominant fail mode with cohesive failure inside adhesive, which seemed to be closely related to the increasing bonding strength possibly not only due to higher Cr surface roughness, but also to penetrated channeling crack density. Also, increasing density of penetrated channeling cracks in electroplating Cr layer led to slightly stronger bonding strength due to mechanical interlocking effects of adhesive inside channeling cracks.

• Journal of the Korean Electrochemical Society
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• v.12 no.3
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• pp.258-262
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• 2009

The composition and semiconducting properties of the passive films formed on Ni- (15, 30)Cr-5Mo alloys in pH 8.5 buffer solution were examined. The depth concentration profile of passive films formed on Ni-(15, 30)Cr-5Mo in pH 8.5 buffer solution showed that Mo enhances the enrichment of Cr. The Mott-Schottky plot for the passive film on Ni-(15, 30)Cr- 5Mo closely resembled that for the film on Cr, whereas those for the less Cr-enriched film on Mo-free alloys showed similar behavior to that for the film on Ni. The acceptor density was reduced by increasing Cr content in Ni-(15, 30)Cr-(0, 5)Mo alloys, but addition of Mo considerably increased the acceptor density.

• Korean Journal of Materials Research
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• v.26 no.7
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• pp.393-399
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• 2016

Flower-like nickel oxide (NiO) catalysts were coated on NiCrAl alloy foam using a hydrothermal method. The structural, morphological, and chemical bonding properties of the NiO catalysts coated on the NiCrAl alloy foam were investigated by field-emission scanning electron microscopy, scanning electron microscopy-energy dispersive spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy, respectively. To obtain flower-like morphology of NiO catalysts on the NiCrAl alloy foam, we prepared three different levels of pH of the hydrothermal solution: pH-7.0, pH-10.0, and pH-11.5. The NiO morphology of the pH-7.0 and pH-10.0 samples exhibited a large size plate owing to the slow reaction of the hydroxide ($OH^-$) and nickel ions ($Ni^+$) in lower pH than pH-11.5. Flower-like NiO catalysts (${\sim}4.7{\mu}m-6.6{\mu}m$) were formed owing to the fast reaction of $OH^-$ and $Ni^{2+}$ by increased $OH^-$ concentration at high pH. Thus, the flower-like morphology of NiO catalysts on NiCrAl alloy foam depends strongly on the pH of the hydrothermal solution.

• Proceedings of the Korean Magnestics Society Conference
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• 1994.03a
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• pp.84-85
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• 1994

• 한국전기화학회:학술대회논문집
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• 2004.04a
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• pp.32-32
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• 2004

• Journal of Technologic Dentistry
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• v.34 no.4
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• pp.337-344
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• 2012

Purpose: This study examined the corrosion level by alloy type and pH, and used the corrosion levels as the dental health data. The study utilized one Ni-Cr alloy for the full and removable partial denture metal frameworks and two Ni-Cr alloys for porcelain-fused-to-metal crown, among the non-beryllium dental casting non-precious Ni-Cr alloys. Methods: The alloy specimens were manufactured in $10cm^2$ and stored in the corrosive solution(pH 2.2-4.4) in the electrical water bath($37^{\circ}C$) for seven days. Afterwards, the metal ions were quantitatively analyzed using the ICP. Results: Of the three metal alloys, Bellabond-Plus$^{(R)}$alloy and SOLIBOND N$^{(R)}$alloy, with 22% or higher chrome chemical contents, had higher corrosion resistance than Jdium-100$^{(R)}$alloy with 20% chrome chemical content. In all three alloys, the corrosion of Ni was highest, and metal ion corrosion was higher in the pH 2.2 corrosive solution. Conclusion: Although Ni-Cr alloy was not very corrosive, a Ni-allergic patient should not have Ni-Cr alloy prosthesis. The Ni-Cr alloy for porcelain-fused-to-metal crown should be designed for the dental porcelain to cover the whole crown.

• Bulletin of the Korean Chemical Society
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• v.24 no.8
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• pp.1215-1218
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• 2003

An analysis of the bonding situation in CaM₂P₂ (M=Fe, Ni) with ThCr₂Si₂ structure is made in terms of DOS and COOP plots. The main contributions to covalent bonding are due to M-P and P-P interactions in both compounds. Particularly, the interlayer P-P bonding by variation in the transition metal is examined in more detail. It turns out that the shorter P-P bonds in CaNi₂P₂ form as a result of the decreasing electron delocalization into ${{\sigma}_p}^*$ of P₂ due to the weaker bonding interaction between the metal d and ${{\sigma}_p}^*$ as the metal d band is falling from Fe to Ni.

• Journal of Technologic Dentistry
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• v.35 no.1
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• pp.1-17
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• 2013

Purpose: This study was to assess the extents of the release of metals from the non-precious alloys used for dental casting by measuring the differences in the extents of the release of metals by types of alloys, pH level and elapsed time. Methods: Uniform-sized specimens(10 each) were prepared according to the Medical Device Standard of the Korea Food and Drug Administration(2010) and International Standard Organization(ISO22674, 2006), using four types of alloys(one type of Ni-Cr and one type of Co-Cr used for fixed prosthesis, and one type of Ni-Cr and one type of Co-Cr used for removable prosthesis). A total of 12 metal-release tests were performed at one-day, three-day, and two-week intervals, for up to 20 weeks. The metal ions were quantified using an Inductively Coupled Plasma-Atomic Emission Spectrometer. Results: The results showed that the extent of corrosion was higher in the ascending order of Jdium-$100^{(R)}$, Bellabond-$Plus^{(R)}$, Starloy-$C^{(R)}$, and Biosil-$F^{(R)}$. The lower the pH and the longer the elapsed time were, the greater the increase in metal corrosion. At pH 2.4, the release of Ni from Jdium-$100^{(R)}$, a Ni-Cr alloy, was up to 15 times greater than the release of Co from the Co-Cr alloy from two weeks over time, indicating that the Ni-Cr alloy is more susceptible to corrosion than the Co-Cr alloy. Conclusion: It is recommended that Co-Cr alloy, which is highly resistant to corrosion, be used for making dental prosthesis with a non-precious alloy for dental casting, and that non-precious alloy prosthesis be designed in such a way as to minimize the area of its oral exposure. For patients with non-precious alloy prostheses, a test of the presence or absence of periodontal tissue inflammation or allergic reaction around the prosthesis should be performed via regular examination, and education on the good management of the prosthesis is needed.