• 공업화학
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• 제30권6호
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• pp.757-761
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• 2019

고정층 상압 유통식 반응기를 사용하여 M(1)-Ni(5)/AlCeO₃ (M = La, Ce, Y) 촉매상에서 메탄의 부분 산화 반응을 수행하여 수소의 수율을 조사하였다. XRD 분석으로 반응 전과 반응 후의 환원된 La(1)-Ni(5)/AlCeO₃ 촉매의 결정상 특성피크를 조사하였고 FESEM과 EDS 분석으로 La, Ni, Ce 금속 입자가 촉매 표면상에 균일하게 분포하고 있음을 조사하였다. XPS 분석으로 촉매 표면상에 O^2-, O₂^2-의 산소와 Ce³⁺, Ce⁴+, La³⁺, Ni²⁺ 등의 이온이 존재함을 알 수 있었고, Ni(5)/AlCeO₃ 촉매에 1 wt%의 La를 첨가하면 Ni2p_3/2과 Ce3d_5/2의 원자가 각각 52.7과 6.3%로 증가하였다. La(1)-Ni(5)/AlCeO₃ 촉매상에서 수소의 수율은 89.1%이었으며, M(1)-Ni(5)/AlCeO₃ (M = Ce, Y)보다 매우 우수하였다. AlCeO₃이 산소와 반응하여 만들어진 CeO₂의 Ce⁴⁺ 이온이 La³⁺로 치환됨으로서 격자에 산소 빈자리를 만들고 strong metal-support interaction (SMSI) 효과로 Ni 원자의 분산을 증가시켜 수소 수율를 향상시켰다.

• 열처리공학회지
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• 제15권2호
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• pp.65-69
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• 2002

$Llo{\rightarrow}Ni_5Al_3$ reordering and related properties in Ni-Al alloys consisting of 64-65at%Ni are characterized by X-ray diffraction, shape memory effect and damping capacity. Formation of $Ni_5Al_3$ takes place by simple ordering of atoms with a continuous increase in c/a ratio. As a result, degradation of shape memory effect and damping capacity is observed after short time annealing at $200-300^{\circ}C$.

• 열처리공학회지
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• 제33권1호
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• pp.1-12
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• 2020

In this study, thin foil fabrication using Ni/Ni₃Al single crystal was performed by cold-rolling. It was found that the cold-rolling behavior was strongly dependent on the initial crystallographic orientation rather than morphology of Ni₃Al precipitates. The deformation banding was formed in the case of (100)[001]- and (210)[001]-oriented specimens at 83% reduction in thickness. However, the effects of Ni₃Al precipitates morphology on the microstructure evolution of Ni/Ni₃Al single crystals during cold-rolling were not so serious comparing with the effects of initial crystallographic orientation. Therefore, it could be concluded that the deformation behavior of Ni/Ni₃Al single crystals at serious strain level was strongly dependent on the initial crystallographic orientation rather than the morphology of Ni₃Al precipitates, whereas the initial deformation behavior was related to both crystallographic orientation and the morphology of Ni₃Al precipitates.

• Tribology and Lubricants
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• 제28권2호
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• pp.56-61
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• 2012

In order to investigate the possibility of Ni-Al based intermetallics coating onto aluminum substrate, the coating process for induction heating has been evaluated by microscopically analyzing the intermetallic layers coated at temperatures lower than the melting temperature of aluminum. The coating layers were divided into two parts with different microstructure along the depth. Hard $NiAl_3$ layer was found at lower parts of the coatings near the interface with aluminum substrate. This layer was formed by the diffusion of aluminum atoms from the substrate into the coating layer across the interface during the induction heating. Meanwhile, at the upper parts of the coating near the surface, a large amount of un-reacted Ni was still remained and surrounded by several Ni-Al based intermetallic compounds, such as $Ni_3Al$, NiAl and $Ni_2Al_3$ formed by the lattice diffusion.

• 한국분말재료학회지
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• 제7권3호
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• pp.161-167
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• 2000

Mechanically-alloyed NiAl powder and ball-milled (Ni+Al) powder mixture were sintered by spark-plasma sintering(SPS) process. Mechanical alloying was performed in a horizontal attritor for 20 h with rotation speed of 600 rpm. (Ni+Al) powder mixtures were prepared by ball milling for 1 and 10 h with 120 rpm. Both powders were sintered at $1150^{\circ}C$ for 5 min under $10^{-3}$ torr vacuum with 50 MPa die pressure in a SPS facility. Sintered densities of 97% and 99% were obtained from mechanically-alloyed NiAl powder and (Ni+Al) powder mixture, respectively. The sintered compact of (Ni+Al) powder mixture showed large grain size by a very rapid grain growth, while the grain size of mechanically-alloyed NiAl powder compact after sintering was extremely fine(80 nm). The difference in densification behavior of both powders were discussed.

• 한국분말재료학회지
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• 제7권3호
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• pp.143-148
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• 2000

NiAl alloy powders were prepared by mechanical alloying method and bulk specimens were produced using hot isostatic pressing techniques. This study focused on the transformation behavior and properties of Ni-Al mechanically alloyed powders and bulk alloys. Transformation behavior was investigated by differential scanning calorimeter (DSC), XRD and TEM. Particle size distribution and microstructures of mechanically alloyed powders were studied by particle size analyzer and scanning electron microscope (SEM). After 10 hours milling, XRB peak broadening appeared at the alloyed powders with compositions of Ni-36at%Al to 40at%Al. The NiAl and $Ni_3Al$ intermetallic compounds were formed after water quenching of solution treated powders and bulk samples at $1200^{\circ}C$, but the martensite phase was observed after liquid nitrogen quenching of solution treated powders. However, the formation of $Ni_3Al$ intermetallic compounds were not restricted by fast quenching into liquid nitrogen. It is considered to be caused by fast diffusion of atoms for the formation of stable $\beta$(NiAl) phase and $Ni_3Al$ due to nano sized grains during quenching. Amounts of martensite phase increased as the composition of aluminium component decreased in the Ni-Al alloy, which resulted in the increasing damping properties.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.374-375
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• 2013

Al/Ni 나노 멀티 포일은 상온에서 외부 방전 및 촉발에 따라 급속한 자기 발열 반응이 일어나는 특성을 보여, 외부 촉발을 통해 상온에서 온도를 높일 수 없는 접합이나 마이크로 수준의 미세 접합이 가능한 접합재료로서 활용이 상당히 기대되는 재료이다. 본 연구에서는 스퍼터링법을 이용하여 한 층이 20 nm 이하에서 Al과 Ni의 혼합 기준을 달리한 Al/Ni 나노 멀티 900층을 제조와 제조된 반응성 포일이 자기 발열 반응에 따른 미세구조에 대해 조사하였다. 박막의 증착은 3~10 mTorr의 공정압력 으로 Al 타겟 전류 1.7 A, Ni 타겟 전류 1.4 A로 하여 증착시간을 조절하여 제조하였다. SEM과 EDX를 통하여 Al/Ni 나노 멀티 포일의 성장구조와 각 원소의 함량을 조사하였다. XRD 미세결정구조 분석은 제조된 반응성 포일과 외부 촉발시킨 후 자기 발열 반응에 의해 형성되는 혼합 상에 대한 조사를 실시하였다. 혼합기준이 1:1의 Al/Ni 나노 멀티 포일에서 약 $980^{\circ}C$의 발열이 발생하는 것을 Pyrometer를 통해 측정하였으며, 자기 발열 반응 후의 혼합 상은 AlNi이 형성되었다. Ni rich 포일에서는 약 $730^{\circ}C$의 발열이 발생하였고, 혼합상으로 주로 AlNi이 형성되었고 Al3Ni2도 나타났으며, 반응에 참여하지 못한 Ni이 남아있는 것을 관찰하였다. Al rich 포일에서는 약 $720^{\circ}C$의 발열과 함께 AlNi, $AlNi_3$이 형성되었고 반응에 참여하지 못한 Al이 미세하게 나타났다.

• 한국세라믹학회지
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• 제28권8호
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• pp.593-602
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• 1991

Al2O3 and NiO-doped Al2O3 powders were prepared from the ethanol solution of Al (NO3)3$.$9H2O and Ni(NO3)2$.$6H2O by spray pylolysis method using two-fluid nozzle. As a result of spraying test with 0.3 mol/{{{{ iota }} concentration starting solution, mean droplet sizes varied with 8.99∼9.69$\mu\textrm{m}$ and those standard deviation were 4.57∼5.12. As-prepared powders which were synthesized at 1000$^{\circ}C$ have spherical shape, sizes of 0.1∼3.0$\mu\textrm{m}$ and specific surface area of 22.34∼24.20㎡/g. Most powders consisted of {{{{ gamma }}-Al2O3 phase and transforned into ${\alpha}$-A;2O3 phase by calcination at 1100$^{\circ}C$ for 1 hr. NiO-doped Al2O3 sintered bodies had better sinterability than those of pure Al2O3 and 0.3 wt% NiO-doped Al2O3 had near theoretical density and dense microstructure.

• 한국재료학회지
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• 제14권2호
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• pp.110-114
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• 2004

High velocity oxy-fuel sprayed NiCoCrAlY coatings were oxidized between 1000 and $1200^{\circ}C$ in air, and the oxide scales were examined by XRD, SEM/EDS, and EPMA. The unoxidized coatings consisted mainly of ${\gamma}$'$-Ni_3$Al, with some ${\gamma}$-Ni. The major oxide formed on the coatings was $\alpha$ $-Al_2$$O_3$. Additionally, (CoCr$_2$$O_4$, $CoAl_2$$O_4$) spinels and $Al_{5}$ $Y_3$$O_{12}$ coexisted. NiO was not found, despite of high amount of Ni in the coating. Below the oxide layer, internally formed $Al_2$$O_3$ existed.

• 한국표면공학회지
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• 제35권2호
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• pp.101-106
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• 2002

The microstructural changes of $NiCrAlY/ZrO_2$-$Y_2$$O_3$ composite coatings that were manufactured by air-plasma-spraying were investigated using XRD and SEM/EDS. The as-sprayed microstructure consisted of (Ni,Cr)-rich regions, ($ZrO_2$-$Y_2$$O_3$)-rich regions, and $Al_2$$O_3$-rich layers that were formed during spraying owing to the oxidation of Al in NiCrAlY. During oxidation between 900 and $1100^{\circ}C$ in air, Cr in the (Ni,Cr)-rich regions diffused toward the $Al_2$$O_3$-rich layers, and oxidized to be dissolved in $A1_2$$O_3$-rich layers. The oxidation of Ni in the (Ni,Cr)-rich regions was less distinct, except at the outer surface of the coating.