• 제목/요약/키워드: Ni-coated Al powder

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무전해코팅법으로 제조한 Al2O3/Ni 나노 Composite의 TEM 미세조직 (TEM Microstructure of Al2O3/Ni Nanocomposites by Electroless Deposition)

  • 한재길;이재영;김택수;이병택
    • 한국분말재료학회지
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    • 제10권3호
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    • pp.195-200
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    • 2003
  • Ni coated $Al_2O_3$ composite was successfully Prepared by the electroless deposition Process. The average size of Ni particles coated on the $Al_2O_3$ matrix powder was about 20 nm. It was hard to find any reaction compound as an impurity at interface between $Al_2O_3$ and Ni particles after sintering. The characterization of microstructure crystal structure and fracture behavior of the sintered body were investigated using XRD, TEM and Victors hardness tester, and compared with those of the sintered $Al_2O_3$ monolithic body. Many dislocations were observed in the Ni phase due to the difference of thermal expansion coefficient between $Al_2O_3$ and Ni phase, and no observed microcracks at their $Al_2O_3$ and Ni interface. In the $Al_2O_3$/Ni composite, the main fracture mode showed a mixed fracture with intergranular and transgranuluar type having some ,surface roughness. The fracture toughness was slightly increased due to the plastic deformation mechanism of Ni phase in the $Al_2O_3$/Ni composite.

니켈 나노입자가 흡착된 에너제틱용 고반응성 알루미늄 분말 합성 (Synthesis of Nickel Nanoparticle-adsorbed Aluminum Powders for Energetic Applications)

  • 김동원;권구현;김경태
    • 한국분말재료학회지
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    • 제24권3호
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    • pp.242-247
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    • 2017
  • In this study, the electroless nickel plating method has been investigated for the coating of Ni nanoparticles onto fine Al powder as promising energetic materials. The adsorption of nickel nanoparticles onto the surface of Al powders has been studied by varying various process parameters, namely, the amounts of reducing agent, complexing agent, and pH-controller. The size of nickel nanoparticles synthesized in the process has been optimized to approximately 200 nm and they have been adsorbed on the Al powder. TGA results clearly show that the temperature at which oxidation of Al mainly occurs is lowered as the amount of Ni nanoparticles on the Al surface increases. Furthermore, the Ni-plated Al powders prepared for all conditions show improved exothermic reaction due to the self-propagating high-temperature synthesis (SHS) between Ni and Al. Therefore, Al powders fully coated by Ni nanoparticles show the highest exothermic reactivity: this demonstrates the efficiency of Ni coating in improving the energetic properties of Al powders.

에너제틱 응용을 위한 Ni코팅된 Al분말소재 제조 및 산화거동 (Fabrication and Oxidation Behaviors of Nickel-coated Aluminum Powders for Energetic Applications)

  • 김경태;우재열;유지훈;이혜문;임태수;최윤정;김창기
    • 한국입자에어로졸학회지
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    • 제10권4호
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    • pp.177-182
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    • 2014
  • In this study, nickel-coated aluminum (Ni/Al) powders were synthesized for the utilization of energetic applications. Oxide materials present at the surface of Al powders of $45{\mu}m$ in averaged size were removed by using sodium hydroxide(NaOH) solution which is used for controlling pH. Nickel material is coated into the surface of oxide-removed Al powders by electroless-plating process. The microstructure of fabricated Ni/Al powders shows that nickel layers with a few hundreds nm were very homogeneously formed onto the surface of Al powders. The oxidation behavior of Ni/Al exihibit somewhat faster oxidation rate than that of pure Al with surface oxidation. Also, the higher exothermic reaction was observed from the Ni/Al powders. From the result of this, nickel coating is very promising method to obtain highly reactive and safe Al powders for energetic applications.

연소합성 코팅된 NiAl 금속간화합물의 화학양론이 미끄럼 마모특성에 미치는 영향 (Effects of Stoichiometry on Properties of NiAl Intermetallics coated on Carbon Steel through Combustion Synthesis)

  • 이한영;이재성
    • Tribology and Lubricants
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    • 제36권3호
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    • pp.124-132
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    • 2020
  • The effect of the stoichiometry on the sliding wear properties of NiAl coatings has been investigated. Three different powder mixtures with the compositions of Ni-50at%Al, Ni-54at%Al and Ni-42at%Al were diepressed respectively, and which were subsequently coated on mild steel through combustion synthesis in an induction heating system. Sliding wear behavior of the coatings was examined against an alloyed tool steel using a pin-on-disc type sliding wear test machine. As results, it could be seen that powder mixture(Ni-54at%Al) with displaying Al-rich deviations from the stoichiometry of NiAl(Ni-50at%Al) was promoted the most the synthetic reactivity. The microstructure of the coating layer with the compositions of Ni-54at%Al exhibits the porous NiAl single phase structure. However, the microstructure of the coating layer of the compositions of Ni-42at%Al exhibits the denser multi-phase structure containing several intermediate phases in addition to NiAl. Densification of the coating layer was enhanced by increasing the reacting temperature. On the other hand, the wear properties of the coating layers showed that the wear mode at speeds of around 1 m/s was severe wear, regardless of the stoichiometry and reacting temperature. However, wear properties of coating layer with the compositions of Ni-42at%Al were superior to those of coating layer with the compositions of Ni-54at%Al. This would be attributed by the fact that coating layer with the compositions of Ni-42at%Al develops little void and much intermediate phases with high strength.

회전원반분사법에 의한 CuA1Ni계 합금 분말제조 (Powder Production of CuAINi Base Alloy via Rotating Disk Atomization)

  • 류봉선
    • 한국분말재료학회지
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    • 제1권2호
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    • pp.145-152
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    • 1994
  • Atomizing mode and powder characteristics of CuA1Ni base shape memory alloy in rotating disk atomization were investigated in accordance with disk materials and additional elements. Produced powders were classified into two types of spherical and flake shape. In the case of CuAlNiBTi and CuAlNiZr alloy, high yield rate and fine powder were obtained. This tendency was same when we used oxide coated disks. We concluded that this results were steno from the wetting characteristics change between molten metal and disk surface. Especially, due to the reactive properties of Ti and Zr with ceramic disk, the change of atomizing appearance and powder characteristics were noticeable.

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주철의 용탕열을 이용한 Ni-Al계 금속간화합물의 연소합성 코팅에 미치는 Ball Milling의 영향 (The Effect of Ball-Milling of Elemental Powders on Ni-Al Based Intermetallic Coatings using the Heat of Molten Cast Iron)

  • 이한영;조용재;김태준;방희장
    • 대한금속재료학회지
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    • 제50권1호
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    • pp.28-33
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    • 2012
  • Ball-milled Ni-Al powder compacts have been synthesized by the heat of molten cast iron and have been coated on cast iron. The effects of the ball-milling time on the microstructure of the intermetallic coatings have been investigated. The experimental results showed that the ball-milled Ni-Al powder compacts were completely reacted and were successfully coated on the cast iron without re-melting the substrate. Densification of the coating layers was enhanced by increasing the ball-milling time. This might be attributed to the fact that the heat released during the intermetallic reaction was dispersed over a prolonged reaction time by the ball-milling of the elemental powders.

반응소결법으로 제조한 Iron Aluminide-Cu 및 Ni-P 피복 $SiC_p$ 예비성형체의 특성평가 (Characteristic Evaluation of Iron Aluminide-Cu and Ni-P Coated $SiC_p$ Preform Fabricated by Reactive Sintering Process)

  • 차재상;김성준;최답천
    • 한국주조공학회지
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    • 제22권1호
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    • pp.42-48
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    • 2002
  • Effects of coating treatment of metallic Cu, Ni-P film on $SiC_p$, for $SiC_p$/iron aluminide composites were studied. Porous hybrid preforms were fabricated by reactive sintering after mixing the coated $SiC_p$, Fe and Al powders. Then the final composites were manufactured by squeeze casting after pouring AC4C Al alloy melts in preforms. The change of reactive temperature, density, microstructure of the preforms and microstructure of the composites were investigated. The exprimental results were summarized as follows. The thickness of Cu and Ni-P metallic layer formed on $SiC_p$ by electroless plating method were about $0.5{\mu}m$ and coated uniformly. There was no remakable change in the ignition temperature with variation of the mixing ratio of Fe and Al powder while in the case of coated $SiC_p$ it was lower about $20^{\circ}C$ than in the non-coated $SiC_p$. The maximum reaction temperature increased with increasing Al contents, but decreased with increasing $SiC_p$ contents. Expansion ratio of preform after reactive sintering increased with amount of Cu coated $SiC_p$. In the case of Fe-70at.%Al, the expansion ratio was about 7% up to 8wt.% of $SiC_p$, addition but further addition of $SiC_p$, increased the ratio significantly. And in the case of Fe-50 and 60at.%Al, it was about 20% up to 16wt.% of $SiC_p$ addition and about 28% in 24wt.% of $SiC_p$, addition. The microstructures of compounds showed that the grains became finer as amount of $SiC_p$, and mixing ratio of iron powder increased and the shape of compounds was changed gradually from irregular to spheroidal.

Cu-Al-Ni계 금속간화합물의 연소합성 Coating에 미치는 Ball Mill처리의 영향 (The Effect of Ball-milling Energy on Combustion Synthesis Coating of Cu-Al-Ni Based Intermetallics)

  • 이한영
    • Tribology and Lubricants
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    • 제27권1호
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    • pp.1-6
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    • 2011
  • The possibility of Cu-Al-Ni intermetallic coating on the mild steel through the combustion synthesis has been investigated. In particular, the effect of the ball milling energy on the microstructure of the coating layer was examined to obtain the best coating condition. Experimental results show that Cu-Al-Ni powder compact was explosively synthesized and successfully coated with the steel matrix. It was revealed that the formation of $Cu_9Al_4$ intermetallic decreased with increase in the ball milling energy. This result supports that the high energy ball milling would be effective for obtaining the most suitable microstructure for Cu-Al-Ni coating layer. However, the excessive ball milling energy seems to decrease the bonding strength between the coating layer and the matrix.

저온 연소합성 후 확산 열처리한 $Ni_{3}Al$ 금속간화합물 코팅층의 미끄럼 마모거동 (Analysis of Wear Properties for $Ni_{3}Al$ Layer coated on Ferrous Materials by Diffusion Treatment after Combustion Synthesis at low Temperature)

  • 이한영
    • Tribology and Lubricants
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    • 제25권1호
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    • pp.7-12
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    • 2009
  • Coating brittle intermetallic compounds on metal can enlarge the range of their use. It is found that intermetallic compound coating layers made by only combustion synthesis in an electric furnace have porous multi-phase structures containing several intermediate phases, even though the coating layers show good wear resistance. In this study, dense $Ni_{3}Al$ single phase layer corresponding to the initial composition of the mixed powder is coated on two different ferrous materials by the diffusing treatment after combustion synthesis. After- ward, sliding wear behaviors of the coating layer are evaluated in comparison with that of the coating layer with porous multi-phase structure made by only combustion synthesis. As a result, the wear properties of the coating layer composed of dense $Ni_{3}Al$ single phase are considerably improved at the range of low sliding speed com- pared with that of the coating layer with porous multi-phase structure, particularly in the running-in wear region. This is attributed to the fact that wear of the coating layer is progressed by shearing as a sequence of adhesion, not by occurring of pitting on the worn surface due to having dense structure without pores.

수증기 메탄 개질 반응을 이용한 수소 생산용 Ni-Cr-Al 다공체 지지 촉매의 제조, 기계적 안정성 및 수소 환원 효율 (Fabrication of Ni-Cr-Al Metal Foam-Supported Catalysts for the Steam Methane Reforming (SMR), and its Mechanical Stability and Hydrogen Yield Efficiency)

  • 김규식;강태훈;공만식;박만호;윤중열;안지혜;이기안
    • 한국분말재료학회지
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    • 제28권3호
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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%.