• 한국표면공학회지
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• 제27권4호
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• pp.223-233
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• 1994

It is well known that compositionally modulated Cu-Ni alloy can be produced by an electrochemical method in Ni sulfate solution containing trace amount of Cu. a mathematical model is presented to describe the current distribution and weight percent of Cu in Ni layer on the rotating disk electrode. The model includes convective-diffusion equation, the Laplace's equation and various overpotentials, and is solved numerically. The thickness of Cu layer is almost uniform whereas the thickness of Ni layer as well as the Ni/Cu weight ratio are increased approaching to the edge of the disk. These results agree well with the experimental values. The ohmic potential drop is suggested as a major cause of a nonuniformity in Ni layer. The optimum plating condition for the fabrication of susperlattice is proposed based on the results of this study.

• 공업화학
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• 제8권4호
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• pp.568-574
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• 1997

Ni/MH전지에서 Cu 도금이 MH(metal hydride)음극의 전극 특성에 미치는 영향을 실험적으로 조사하였다. $LaNi_5$와 Cu도금된 $LaNi_5$를 활물질로 사용하여 냉간압착법과 페이스트법의 혼용법으로 전극을 제조하였다. 그 결과 소량의 CMC(carboxymethylcellulose sodium salt)를 첨가하고 열처리를 행하지 않은 전극이 높은 방전용량을 보였다. $LaNi_5$보다는 Cu 도금된 $LaNi_5$를 활물질로 사용하여 제조한 전극의 방전용량이 증가하였으며, 이는 $LaNi_5$표면에 도금된 구리에 의해 전극의 전자 전도도가 증가되었기 때문이며 도금된 구리의 양이 증가할 수록 그 효과는 현저하였다. 또한 전극의 방전용량은 산성 무전해도금의 경우가 알칼리성 무전해도금을 행한 전극보다 우수한 용량을 나타내었다. Al이 첨가된 $LaNi_{4.5}Al_{0.5}$ 전극이 $LaNi_5$전극보다 우수한 방전용량을 보였다. 구리 도금이 $LaNi_5$의 피독특성에 미치는 영향을 CO기체의 피독실험으로 조사하였다.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 2000년도 High Temperature Superconductivity Vol.X
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• pp.56-60
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• 2000

Cube texture를 갖는 Ni기판위에 MOCVD(Metal Chemical Vapor Deposition)를 이용하여 NiO, CeO$_2$, YBCO 박막을 제조하였다. NiO(200)와 CeO$_2$(200) buffer layer는 450${\sim}$470$^{\circ}$C에서 10분간 MOCVD방법으로 (100)<001>Ni 기판위에 직접 증착하였다. 제조된 NiO, CeO$_2$ buffer layer는 조직이 치밀하며 표면의 상태가 매우 좋으며 Ni기판 위에 epitaxial하게 성장하였다. NiO는 Ni기판과 NiO<100>//Ni<100>의 방위관계를 가지고 성장하였으며, CeO$_2$는 증착조건에 따라 CeO$_2$ <100>//Ni<100> 및 CeO$_2$ <110>//Ni<100> 의 방위관계를 가지고 성장하였다. 증착된 NiO막과 CeO$_2$막에서 균열은 발생하지 않았다. MOCVD법으로 표면에 biaxial texture를 갖는 ceramic buffer를 증착시킨 NiO/Ni및 CeO$_2$/Ni 기판위에 YBCO박막을 MOCVD법으로 제조하였다. YBCO막은 기판온도 800$^{\circ}$C,증착압력 10torr, 산소분압을 0.7torr로 하여 10분간 행하였다. 공급원료의 조성에 따라 YBCO의 막의 texture와 형성되는 상이 변화되었다. NiO/Ni및 CeO$_2$/Ni 기판 위에 증착된 YBCO막은 c축 배향성을 가지고 성장하였으며, -scan 및 ${\varphi}$ -scan으로 측정한 (500)면의 in-plane과 (110)면의 out-of-plane의 FWHM(Full Width Half Maximum)값은 각각 10$^{\circ}$ 미만으로 우수하였다.

• 한국자기학회지
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• 제15권1호
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• pp.7-11
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• 2005

비자성 전이금속인 Rh 여러 층 사이에 자성 전이금속인 Ni 한층을 넣은 4Rh/Ni/4Rh(001) 계에서 Rh과 Ni의 자기 모멘트 진동현상을 FLAPW(full-potential linearized augmented plane wave) 방법을 이용하여 연구하였다. 가운데 층에 있는 Ni의 자기 모멘트를 계산한 결과는 0.34${\mu}_B$으로 덩치 Ni의 값보다 약 40% 감소한 값이다. Ni과의 강한 띠 혼성으로 Rh의 각 원자 층에 자기모멘트의 변화가 나타났는데 이 변화는 중심에서 표면으로 갈수록 작아지는 감쇠 진동을 하였다. Rh의 영향을 받아 가운데 Ni층의 폐르미 준위가 Ni의 에너지 띠 안쪽으로 이동하여 Ni의 전자수가 줄어들고 있음을 계산된 상태밀도 모양에서 알 수 있었다.

• 한국분말재료학회지
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• 제10권6호
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• pp.406-414
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• 2003

In order to produce good wear resistance powder metallurgy Al-Si alloys with high strength, addition of glass forming elements of Ni and Ce in $Al_{81}$Si$_{19}$ alloy was examined using SEM, TEM, tensile strength and wear testing. The solubility of Si in aluminum increased with increasing Ni and Ce contents for rapidly solidified powders. These bulk alloys consist of a mixed structure in which fine Si particles with a particle size below 500 nm and very fine A1$_3$Ni, A1$_3$Ce compounds with a particle size below 200 nm are homogeneously dispersed in aluminum matrix with a grain size below 600 nm. The tensile strength at room temperature for $Al_{81}$Si$_{19}$, $Al_{78}$Si$_{19}$Ni$_2$Ce$_{0.5}$, and $Al_{76}$Si$_{19}$Ni$_4$Ce$_1$ bulk alloys extruded at 674 K and ratio of 10 : 1 is 281,521, and 668 ㎫ respectively. Especially, $Al_{73}$Si$_{19}$Ni$_{7}$Ce$_1$ bulk alloy had a high tensile strength of 730 ㎫. These bulk alloys are good wear-resistance bel ter than commercial I/M 390-T6. Specially, attactability for counterpart is very little, about 15 times less than that of the I/M 390-T6. The structural refinement by adding glass forming elements such as Ni and Ce to hyper eutectic $Al_{81}$Si$_{19}$ alloy is concluded to be effective as a structural modification method.d.tion method.

• 대한치과기공학회지
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• 제40권3호
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• pp.125-131
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• 2018

Purpose: Automatic dental prosthesis manufacturing process was accelerated by the spread of dental CAD / CAM system. The CAD / CAM system with milling alloys were needed supplement. So, sintered alloy blocks were introduced. In this study, we want to study sintered alloy block. And to evaluate the alloy block manufacture and alloy properties. Methods: The alloy powders were prepared by high pressure water dispersion method. The sintered alloy blocks were prepared by low temperature pressing method. Their components observation were EDX, and the alloy structure was observed by XRD. Results: Co-Cr alloy powders were observed to have a circle shape with an average diameter of about $100{\mu}m$ and a Ni-Cr alloy powder had a circle shape with an average diameter of about $50{\mu}m$. The Co-Cr alloy block is composed of Co (34.62 wt%), Cr (17.33 wt%), Mo (2.98 wt%), Si (0.36 wt%) and C (44.17 wt%). The Ni-Cr alloy powder was composed of Ni (40.29 wt%), Cr (19.37 wt%), Mo (3.53 wt%), Si (0.52 wt%) and C (33.18 wt%). The peak of the Co and CoCr peaks were observed in the CoCr alloy body by the means of XRD study. Cr2Ni3 of the peak was observed in the Ni-Cr alloy material. Conclusion : As a result, the following conclusions were obtained. 1. Prepared by high-pressure water-law Co-Cr alloy powder has an average diameter $100{\mu}m$, Ni-Cr alloy powder was found to have the form of sphere having an average diameter $50{\mu}m$. 2. Co-Cr alloy and Ni-Cr alloy block produced by low-temperature processing showed a certain ratio. 3. In the XRD study, Co phase appeared in Co-Cr alloy block after sintering. and Cr2Ni3 phase appeared in Ni-Cr alloy block after sintering.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집 Vol.14 No.1
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• pp.197-200
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• 2001

In this letter, we report on the investigation of Ni/Si/Ni Ohmic contacts to n-type 4H-SiC. Ohmic contacts have been formed by a vacuum annealing and $N_2$ gas ambient annealing method at $950^{\circ}C$ for 10 min. The specific contact resistivity ( $\rho_{c}$ ), sheet resistance($R_s$), contact resistance($R_c$), transfer length($L_T$) were calculated from resistance($R_T$) versus contact spacing(d) measurements obtained from 10 TLM(transmission line method) structures. The resulting average values of vacuum annealing sample were $\rho_{c}=3.8{\times}10^{-5}\Omega cm^{3}$, $R_{c}=4.9{\Omega}$, $R_{T}=9.8{\Omega}$ and $L_{T}=15.5{\mu}m$, resulting average values of another sample were $\rho_{c}=2.29{\times}10^{-4}\Omega cm^{3}$, $R_{c}=12.9{\Omega}$ and $R_{T}=25.8{\Omega}$. The physical properties of contacts were examined using X-Ray Diffraction and Auger analysis, there was a uniform intermixing of the Si and Ni, migration of Ni into the SiC.

• Progress in Superconductivity
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• 제7권2호
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• pp.130-134
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• 2006

Buffer layers such as $CeO_2\;and\;Yb_2O_3$ films for YBCO coated conductors were deposited on (100) $SrTiO_3$ single crystals and (100) textured Ni substrates by a metal organic chemical vapor deposition (MOCVD) system of the hot-wall type. The substrates were moved with the velocity of 40 cm/hr. Source flow rate, $Ar/O_2$ flow rate and deposition temperature were main processing variables. The degree of film epitaxy and surface morphology were investigated using XRD and SEM, respectively. On a STO substrate, the $CeO_2$ film was well grown epitaxially above the deposition temperature of $450^{\circ}C$. However, on a Ni substrate, the XRD showed NiO (111) and (200) peaks due to Ni oxidation as well as (111) and (200) film growth. For the films deposited with $O_2$ gas as oxygen source, it was found that the NiO film was formed at the interface between the buffer layer and the Ni substrate. The NiO layer interrupts the epitaxial growth of the buffer layer. It seems that the epitaxial growth of the buffer layer on Ni metal substrates using $O_2$ gas is difficult. We are considering a new method avoiding Ni oxidation with $H_2O$ vapor instead of $O_2$ gas.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집
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• pp.197-200
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• 2001

In this letter, we report on the investigation of Ni/Si/Ni Ohmic contacts to n-type 4H-SiC. Ohmic contacts have been formed by a vacuum annealing and N$_2$ gas ambient annealing method at 950$^{\circ}C$ for 10 min. The specific contact resistivity($\rho$$\sub$c/), sheet resistance(R$\sub$S/), contact resistance(R$\sub$S/), transfer length(LT) were calculated from resistance(R$\sub$T/) versus contact spacing(d) measurements obtained from 10 TLM(transmission line method) structures. The resulting average values of vacuum annealing sample were $\rho$$\sub$c/=3.8x10$\^$-5/ Ω$\textrm{cm}^2$ , R$\sub$c/=4.9Ω, R$\sub$T/=9.8Ω and L$\sub$T/=15.5$\mu\textrm{m}$, resulting average values of another sample were $\rho$$\sub$c/=2.29x10$\^$-4/ Ω$\textrm{cm}^2$ , R$\sub$c/=12.9Ω, R$\sub$T/=25.8Ω. The Physical properties of contacts were examined using X-Ray Diffraction and Auger analysis, there was a uniform intermixing of the Si and Ni, migration of Ni into the SiC.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1991년도 하계학술대회 논문집
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• pp.217-220
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• 1991

Ni-Zn ferrite powders in the few hundred angstrum size range and up have been synthesized by a wet direct method. The coprecipitate were prepared by adding alkaline solution into the constituent metal ions solution. and subsequent calcined at various temperature. At 95, the particles were ultrafine spherical shaped particles of about 500(A) in diameter.