• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2000.04a
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• pp.42-42
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• 2000

• Applied Microscopy
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• v.43 no.3
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• pp.127-131
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• 2013

The crystallization behavior in the $Al_{87}Ni_3Y_{10}$ and $Al_{88}Ni_3Y_9$amorphous alloys has been investigated. As-quenched $Al_{87}Ni_3Y_{10}$ amorphous phase decomposes by simultaneous formation of Al and intermetallic phase at the first crystallization step, while as-quenched $Al_{88}Ni_3Y_9$ amorphous phase decomposes by forming Al nanocrystals in the amorphous matrix. The density of Al nanocrystals is extremely high and the size distribution is homogeneous. Such a microstructure can result from rapid explosion of the nucleation event in the amorphous matrix or growth of the preexisting nuclei embedded in the as-quenched amorphous matrix. The final equilibrium crystalline phases and their distribution at 873 K are exactly same in both $Al_{87}Ni_3Y_{10}$ and $Al_{88}Ni_3Y_9$ alloys.

• Journal of the Korean institute of surface engineering
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• v.32 no.1
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• pp.67-77
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• 1999

The Ni base superalloy Mar-M247 substrate was aluminized or aluminized after boronizing by the pack cementation under Ar atmosphere. The hot corrosion resistance and after-heat-treatment effect of aluminized specimens were studied by the cyclic hot corrosion test in $Na_2SO_4$-NaCl molten salt. XRD analysis showed that the $Ni_2Al_3$ phase was formed between the coated layer and substrate below 1273K but the NiAl phase above 1273K. The peak of the NiAl phase was developed after heat treatment. Corrosion test showed that corrosion resistance of the specimen with the NiAl phase was better than that with the $Ni_2Al_3$ phase. Corrosion resistance could be improved by heat treatment to form ductile NiAl phase, where cracks were not formed by thermal shock on coating layer. Moreover, it appeared that heat treatment played a role to improve corrosion resistance of Al diffusion coating above 1273K. The existence of boron in the Al diffusion coating layer obstructed outwared diffusion of Cr from the substrate, and it influenced on corrosion resistance of the coating layer by weakening adherence of the oxide scale.

• Korean Chemical Engineering Research
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• v.61 no.3
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• pp.479-486
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• 2023

In this study, we investigated the effect of the Ce_xZr_1-xO₂ (CZ) addition onto Ni/Al₂O₃ catalysts on the catalytic performance in methane steam reforming. In the reaction results, the CZ-added Ni/Al₂O₃ catalyst showed higher CH₄ conversion and H₂ yield under the same reaction conditions than Ni/Al₂O₃. From the characterization data, the two catalysts had similar support porosity and Ni dispersion, confirming that the two properties could not determine the catalytic performance. However, the oxygen vacancy over the CZ-added Ni/Al₂O₃ catalyst induced an efficient steam activation at low reaction temperatures, resulting in an increase in the catalytic activity and H₂ yield.

• Korean Journal of Materials Research
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• v.12 no.12
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• pp.955-961
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• 2002

2.7vol%TiNi/6061 Al composites with TiNi shape memory alloy as reinforcement were fabricated by vacuum hot press. It was investigated by OM, SEM, EPMA and XRD analysis for the behavior of diffusion layer formation on various heat treatment condition. Thickness of diffusion layer was increased proportionally according to heat treatment time. The layer was formed by the mutual diffusion of TiNi and Al. The diffusion rate from TiNi fiber to Al matrix was faster than that of reverse diffusion path. The more diffused layer was formed in Al matrix. The diffusion at interface layer was consisted of $A1_3$Ti, $Al_3$Ni analyzed by EPMA, XRD results.

• Transactions of Materials Processing
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• v.26 no.4
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• pp.216-221
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• 2017

Recently, interest in multifunctional energetic structural materials (MESMs) has grown due to their multifunctional potential, especially in military applications. However, there are few studies about extrinsic factors that govern the reactivity of MESMs. In this paper, a shock compaction process was performed on the nano Ni/Al-mixed powder to investigate the effect of particle size on the shock reaction condition. Additionally, heating the statically compacted specimen was also performed to compare the mechanical properties and microstructure between reacted and unreacted material. The results show that the agglomerated structure of nanopowders interrupts the reaction by reducing the elemental boundary. X-ray diffraction analysis shows that the NiAl and $Ni_3Al$ intermetallics are formed on the reacted specimen. The microhardness results show that the $Ni_3Al$ phase has a higher hardness than NiAl, but the portion of $Ni_3Al$ in the reacted specimen is minor. In conclusion, using Ni/Al composites as a reactive material should focus on energetic use.

• The Journal of Natural Sciences
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• v.7
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• pp.19-25
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• 1995

In this study, the Mossbauer effect of the $NiAl_0.8Fe_1.2O_4$ was investigated in the temperature range of 77K-1000K. The spectra were composed of two component, one is sixtet and the other doublet, at low temperature. From the temperature dependence of Mossbauer spectum, it is appeared that the magnetic properties of $NiAl_0.8Fe_1.2O_4$ varies from ferrimagnetism to paramagnetism as the increasing tempereture. And the magnetic relaxation patterns of the $NiAl_0.8Fe_1.2O_4$ were shown superparamagnetic effect.

• Journal of Advanced Marine Engineering and Technology
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• v.25 no.2
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• pp.344-350
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• 2001

This paper was studied on the characteristics of galvanic corrosion and its protection on heat exchanger tube plate in the sea water. In this paper, behavior of pitting corrosion of Ni-al bronze connected with Ti tube was measured af flow velocity of 0 m/s and 2.4 m/s. To protect galvanic corrosion, the protection characteristics of Ni-Al bronze connected with Ti tube by Zn-base alloys galvanic anode and hexagonal nylon insert was investigated. Main results obtained asre al follows: 1) The galvanic corrosion of Ni-Al bronze connected with Ti-tube is more active than single Ni-al bronze. 2) As the circuit resistance increase under the cathodic protection employing Zn-base alloys galvanic anode, Ni-al bronze connected with Ti tube is cathodically unpolarized. 3) The corrosion of Ni-Al bronze connected with Ti tube by nylon insert controls approximately 73% than not nylon insert.

• Journal of Advanced Marine Engineering and Technology
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• v.25 no.2
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• pp.345-345
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• 2001

This paper was studied on the characteristics of galvanic corrosion and its protection on heat exchanger tube plate in the sea water. In this paper, behavior of pitting corrosion of Ni-al bronze connected with Ti tube was measured af flow velocity of 0 m/s and 2.4 m/s. To protect galvanic corrosion, the protection characteristics of Ni-Al bronze connected with Ti tube by Zn-base alloys galvanic anode and hexagonal nylon insert was investigated. Main results obtained asre al follows: 1) The galvanic corrosion of Ni-Al bronze connected with Ti-tube is more active than single Ni-al bronze. 2) As the circuit resistance increase under the cathodic protection employing Zn-base alloys galvanic anode, Ni-al bronze connected with Ti tube is cathodically unpolarized. 3) The corrosion of Ni-Al bronze connected with Ti tube by nylon insert controls approximately 73% than not nylon insert.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2008.11a
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• pp.94-97
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• 2008

현재 전주 국내에서는 전주에 대한 관심이 조금씩 증가하는 추세지만 그 활용 영역은 많지 않다. 최근들어 휴대폰 관련 부품과 LCD디스플레이의 핵심부품인 도광판 사출금형에 집중되어 있다. 본 연구에서는 반도체 웨이퍼 절단용 블레이드 제작을 목표로 Ni 전주도금층에 조밀하게 $Al_2O_3$를 분산시키는데 목표를 삼았다. 전주(electroforming)를 이용한 Ni-$Al_2O_3$를 첨가한 설파민산 니켈욕에 Surfactant의 양을 조절하며 Sodium Lauryl Sulfate의 첨가량이 많아질수록 Nickel 전주도금층 표면에 $Al_2O_3$는 접착되어지지 않고, 도금층의 두께는 두꺼워졌다. Surfactant의 첨가로인하여 Ni 전주도금층의 표면 장력이 감소하여 $Al_2O_3$를 감싸고 Ni 전주도금층이 성장하여야하는데 교반하는 과정에서 $Al_2O_3$ 입자들이 용액의 흐름에 따라 떨어져 나갔다.