• Korean Journal of Materials Research
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• v.25 no.2
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• pp.95-99
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• 2015

$NiAl_2O_4$ nanoparticle was synthesized by a reverse micelle processing for inorganic pigment. $Ni(NO_3)_2{\cdot}6H_2O$ and $Al(NO_3)_3{\cdot}9H_2O$ were used for the precursor in order to synthesize $NiAl_2O_4$ nanoparticles. The aqueous solution, which consisted of a mixing molar ratio of Ni/Al, was 1:2 and heat treated at $800{\sim}1100^{\circ}C$ for 2h. The average size and distribution of synthesized $NiAl_2O_4$ powders are in the range of 10-20 nm and narrow, respectively. The average size of the synthesized $NiAl_2O_4$ powders increased with an increasing water-to-surfactant molar ratio and heating temperature. The crystallinity of synthesized $NiAl_2O_4$ powder increased with an increasing heating temperature. The synthesized $NiAl_2O_4$ powders were characterized by X-ray diffraction analysis(XRD), a field emission scanning electron microscopy(FE-SEM), and a color spectrophotometer. The properties of synthesized powders were affected as a function such as a molar ratio and heating temperature. Results indicate that synthesis using a reverse miclle processing is a favorable process to obtain $NiAl_2O_4$ spinels at low temperatures. The procedure performed suggests that this new synthesis route for producing these oxides has the advantage of being fast and simple. Colorimetric coordinates indicate that the pigments obtained exhibit blue colors.

• Proceedings of the KWS Conference
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• 2002.10a
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• pp.726-731
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• 2002

Reaction synthesis is a process to form ceramics, intermetallics and their composites from elemental powder mixture. Application of this process to a surface modification techniques has a possibilities to enable the process at a lower temperature or for a shorter time, although synthesized materials are likely to include voids and unreacted elements. This paper intend to examine the effect of Si addition to the mixture of Al and Ni on the densification of synthesized Ni-Al intermetallic compounds and to evaluate the surface properties of obtained coatings. By the Si addition, exothermic reaction temperature to form Ni-Al intermetallic was lowered to be below the melting point of Al. Si soluted $Al_3$Ni$_2$, $Al_3$Ni and $Al_{6}$Ni$_3$Si were mainly formed in the coating layer when powder mixture was heated to 973K for 300s. Besides, densification was enhanced by increasing hot press pressure, Si additions and heating rate. When the composition of eutectic Al-Si reaches 78%, void ratio of sintered compact reduced to 0.4%. It is caused by higher flowability of Al-Si liquid phase generated and its infiltration into the void. Since the hardness of NiAl(Si) compound (about 600HV) formed in the coating layer is higher than that of Ni-Al compound (about 400HV), coating layer with high density and superior wear property is obtained by hot press using reaction synthesis from Al-Ni-Si powder mixture.

• Journal of the Korean institute of surface engineering
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• v.35 no.2
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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.

• Journal of the Korean Magnetics Society
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• v.9 no.6
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• pp.296-300
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• 1999

Cross-shape structures of spin tunneling junctions were fabricated using DC magnetron sputtering and metal masks. The film structures were $substrate/Ta/NiFe/FeMn/NiFe/CoFe/Al_2O_3/CoFe/NiFe$ and $substrate/Ta/NiFe/CoFe/ Al_2O_3/CoFe/NiFe/FeMn/NiFe$. Fabrication conditions of insulating layer ($Al_2O_3$) and thickness and sputtering power of each film layer were varied, and maximum magnetoresistance ratio of 24.3 % was obtained. Magnetic characteristic variations in the above mentioned two structures and two types of substrates (Corning glass 7059 and Si(111)) were compared. Annealing of the junctions was performed to find out magnetic characteristic variations expected from the device fabrication. Magneoresistance Ratio were observed to maintain as-deposited value up to 150 $^{\circ}C$ annealing and then to drop rapidly after 180 $^{\circ}C$ annealing.

• Korean Journal of Metals and Materials
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• v.48 no.12
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• pp.1116-1122
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• 2010

Metal interconnections of multilayer Al/Ni and TiW/seed-Ni/Ni were formed on glass, and the adhesion strength and nanoindentation response of the composite layers were evaluated. The Al/Ni multilayer was formed by an anodic bonding of glass to Al and subsequent electroless plating of Ni, while the TiW/Ni multilayer was fabricated by sputter deposition of TiW and seed-Ni onto glass and electroless plating of Ni. Because of the diffusion of aluminum into glass during the anodic bonding, anodically bonded glass/Al joint exhibited greater interfacial strength than the sputtered glass/TiW one. The Al/Ni on glass also showed excellent resistance against delamination by bending deformation compared to the TiW/seed-Ni/Ni on glass. From the nanoindentation experiment of each metal layer on glass, it was found that the aluminum layer had extremely low hardness and elastic modulus similar to the glass substrate and played a beneficial role in the delamination resistance by lessening stress intensification at the joint. The indentation data of the multilayers also supported superior joint reliability of the Al/Ni to glass compared to that of the TiW/seed-Ni/Ni to glass.

• Journal of the Korean institute of surface engineering
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• v.39 no.3
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• pp.129-136
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• 2006

The high velocity oxy-fuel sprayed coatings of 38Ni-23Co-20Cr-11Al-3Y-5Ta, 25Ni-34Co-20Cr-11Al-3Y-2Re and 32Ni-34.5Co-22Cr-11Al-0.5Ir (in wt%) were oxidized at 1000 and $1100^{\circ}C$ in air in order to find the alloying effect of Ta, Re and Ir on the oxidation properties of the NiCoCrAlY-base coatings. The primary phase of the coatings was $Ni_3Al$. The oxides formed on the coatings consisted primarily of ${\alpha}-Al_2O_3$, together with some $CoCr_2O_4,\;CoAl_2O_4$, and $Al_5Y_3O_{12}$. Tantalum oxidized to $Ta_2O_5$ and $Ta_2O_{22}$. However, no oxides of Re and Ir were detected by XRD owing to their thermodynamic inertness and/or their small amount.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.05a
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• pp.155-158
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• 2002

Fabrication process of metal/intermetallic laminated composites by using self-propagating high temperature synthesis(SHS) reactions between Ni and Al elemental metal foils have been investigated. Al foils were sandwiched between Ni foils and heated in a vacuum hot press to the melting point of aluminium. SHS reaction kinetics was thermodynamically analyzed through the final volume fraction of the unreacted Al related with the initial thickness ratio of Ni:Al and diffusion bonding stage before SHS reaction. Thermal aging of laminated composites resulted in the formation of functionally gradient series of intermetallic phases. Microstructure showed that the main phases of intermetallics were NiAl and $Ni_3Al$ having higher strength at room and high temperatures. The volume fractions of intermetallic phases were measured as 82.4, 58.6, 38.4% in 1:1, 2:1, 4:1 initial thickness ratio of Ni:Al.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1998.03a
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• pp.72-75
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• 1998

High temperature deformation behavior of Al85Ni10Y5 alloy extrudates fabricated with amorphous ribbons was investigated at temperature range form 300 to 550$^{\circ}C$ by torsion tests. Thermal properties of amorphous ribbons as a function of aging temperature was studied by Differential Scanning Calorimetry(DSC). The Al phase crystallite firstly formed in the amorphous ribbons and its crystallization temperature(Tx) was ∼210$^{\circ}C$. During the processings of consolidation and extrusion, nano-grained structure was formed in the Al85Ni10Y5 alloy extrudates. The as-extrudated Al85Ni10Y5 alloy and the Al85Ni10Y5 alloy annealed at 250$^{\circ}C$ for 1 hour showed the flow curve of DRV(dynamic recovery) during hot deformation at 400-550$^{\circ}C$. On the other hand, the Al85Ni10Y5 alloy annealed at 400$^{\circ}C$ for 1 hour showed the flow curve of DRX(dynamic recrystallization) during hot deformation at 450-500$^{\circ}C$.

• Korean Journal of Metals and Materials
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• v.47 no.5
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• pp.267-273
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• 2009

Three types of structural intermetallic compounds, $Ni_3Al$, NiAl and TiAl, having each single phase structure without pores were produced by arc-melting process. Their sliding wear properties were investigated against a hardened tool steel. It was shown that the wear of the intermetallic compounds was hardly occurred against the hardened tool steel. TiAl compound showed the best wear resistance among them. In this case, wear was preferentially occurred on the surface of the hardened tool steel of the mating material which has higher hardness. It could be found that the wear mode on intermetallics without pores by arc-melting process was different from that on its porous layer coated on steel by combustion synthesis.

• Journal of Energy Engineering
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• v.2 no.3
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• pp.293-299
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• 1993

In order to investigate the effect of Al addition on the electrochemical performance and structural stability of porous Ni anode for molten carbonate fuel cell, porous Ni anodes containing Al up to 10 wt% were fabricated by the tape casting technique. In this study half-cell performance of the anodes was evaluated by anodic polarization in the simulated MCFC anode condition(650$^{\circ}C$ , 80% H$_2$＋20% CO$_2$). At the anodic current of 150 ㎃/$\textrm{cm}^2$, the polarizations for H$_2$oxidation of the anode was about 100 ㎷. The sintering and creep resistance of Ni-Al anodes was higher than those of the pure Ni anode. It was considered that the increase of sintering and creep resistance was due to the formation of Al$_2$O$_3$ on the surface of Ni particles.