• Korean Journal of Metals and Materials
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• v.48 no.9
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• pp.819-824
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• 2010

NiTi powders were synthesized during high energy ball milling for 10 h. Highly dense nanostructured NiTi with a relative density of up to 99% was obtained within 1 minute by high frequency induction heated sintering under a pressure of 80 MPa. The grain size, microstructure, and mechanical properties of NiTi were investigated. The grain size and hardness of TiNi are about 122 nm and $590kg/mm^2$, respectively.

• Journal of the Korean Ceramic Society
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• v.55 no.5
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• pp.407-418
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• 2018

Increasing demand for portable and wireless electronic devices with high power and energy densities has inspired global research to investigate, in lieu of scarce rare-earth and expensive ruthenium oxide-like materials, abundant, cheap, easily producible, and chemically stable electrode materials. Several potential electrode materials, including carbon-based materials, metal oxides, metal chalcogenides, layered metal double hydroxides, metal nitrides, metal phosphides, and metal chlorides with above requirements, have been effectively and efficiently applied in electrochemical supercapacitor energy storage devices. The synthesis of self-grown, or in-situ, nanostructured electrode materials using chemical processes is well-known, wherein the base material itself produces the required phase of the product with a unique morphology, high surface area, and moderate electrical conductivity. This comprehensive review provides in-depth information on the use of self-grown electrode materials of different morphologies in electrochemical supercapacitor applications. The present limitations and future prospects, from an industrial application perspectives, of self-grown electrode materials in enhancing energy storage capacity are briefly elaborated.

• Korean Journal of Materials Research
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• v.28 no.11
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• pp.653-658
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• 2018

$ZrO_2$ is a candidate material for hip and knee joint replacements because of its excellent combination of biocompatibility, corrosion resistance and low density. However, the drawback of pure $ZrO_2$ is a low fracture toughness at room temperature. One of the most obvious tactics to cope with this problem is to fabricate a nanostructured composite material. Nanomaterials can be produced with improved mechanical properties(hardness and fracture toughness). The high-frequency induction heated sintering method takes advantage of simultaneously applying induced current and mechanical pressure during sintering. As a result, nanostructured materials can be achieved within very short time. In this study, W and $ZrO_2$ nanopowders are mechanochemically synthesized from $WO_3$ and Zr powders according to the reaction($WO_3+3/2Zr{\rightarrow}W+3/2ZrO_2$). The milled powders are then sintered using high-frequency induction heating within two minutes under the uniaxial pressure of 80MPa. The average fracture toughness and hardness of the nanostructured W-3/2 $ZrO_2$ composite sintered at $1300^{\circ}C$ are $540kg/mm^2$ and $5MPa{\cdot}m^{1/2}$, respectively. The fracture toughness of the composite is higher than that of monolithic $ZrO_2$. The phase and microstructure of the composite is also investigated by XRD and FE-SEM.

• Korean Journal of Materials Research
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• v.23 no.11
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• pp.620-624
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• 2013

Nanocrystalline materials have recently received significant attention in the area of advanced materials engineering due to their improved physical and mechanical properties. A solid-solution nanocrystalline powder, (Ti,Mo)C, was prepared via high-energy milling of Ti-Mo alloys with graphite. Using XRD data, the synthesis process was investigated in terms of the phase evolution. Rapid sintering of nanostuctured (Ti,Mo)C hard materials was performed using a pulsed current activated sintering process (PCAS). This process allows quick densification to near theoretical density and inhibits grain growth. A dense, nanostructured (Ti,Mo)C hard material with a relative density of up to 96 % was produced by simultaneous application of 80 MPa and a pulsed current for 2 min. The average grain size of the (Ti,Mo)C was lower than 150 nm. The hardness and fracture toughness of the dense (Ti,Mo)C produced by PCAS were also evaluated. The fracture toughness of the (Ti,Mo)C was higher than that of TiC.

• Proceedings of the Korean Ceranic Society Conference
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• 2004.10a
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• pp.85.1-85.1
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• 2004

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.128-129
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• 2006

• Proceedings of the Korean Magnestics Society Conference
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• 2008.06a
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• pp.87-87
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• 2008

• Proceedings of the Korean Vacuum Society Conference
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• 2005.02a
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• pp.127-127
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• 2005

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.527-528
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• 2006

Nanostructured Alumina - 20 vol% 3YSZ composites powder were synthesized by wet-milling technique. The starting materials were a mixture of Alumina micro-powder and 3YSZ nano-powders. Nano-crystalline grains were obtained after 24 h milling time. The nano-structured powder compacts were then processed to full density at different temperatures by high-frequency induction heat sintering (HFIHS). Effects of temperature on the mechanical and microstructure properties have been studied. $Al_2O_3-3YSZ$ composites with higher mechanical properties and small grain size were successfully developed at relatively low temperatures through this technique.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2012.05a
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• pp.331-331
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• 2012

In this study, we investigated morphology observation of nanostructured Ti-25Ta-xZr alloys. Ti-25Ta-(3wt%~15 wt%) Zr alloys were prepared by a vacuum arc-melting furnace. Formation of nanotubular structure was achieved by an electrochemical method in 1M $H_3PO_4$ electrolytes containing 0.8%wt.% NaF. Nanotube morphology depended on alloying elements.