• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1427-1429
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• 2003

The $ZnNb_2O_6$ ceramics with 3wt% CuO were prepared by the conventional mixed oxide method. The ceramics were sintered at the temperature of $1000^{\circ}C{\sim}1075^{\circ}C$ for 3hr. in air. The structural properties were investigated with sintering temperature by XRD and SEM. Also, the microwave dielectric properties were investigated with sintering temperature. Increasing the sintering temperature, the peak of second phase($Cu_3Nb_2O_8$) was increased. In the case of $ZnNb_2O_6$+CuO(3wt%) ceramics sintered at $1025^{\circ}C$ for 3hr, the dielectric constant, quality factor were 21.73, 19.276, respectively.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.568-569
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• 2006

The use of the nickel free, high nitrogen stainless steel powder and nitriding during sintering of iron based materials have been shown as an alternative way to the conventional PM stainless steels containing nickel. Nitrogen as an alloying element for iron improves in an effective way the properties of sintered alloyed steels. The powder metallurgy route is a suitable way to introduce nitrogen into these alloys and, in particular, to produce high nitrogen (close to the solubility limit) stainless steels. The paper presents and discusses the nitriding behavior of nickel-free stainless steels produced by powder metallurgy method. Alloyed melt was atomized by nitrogen and in this way nitrogen was introduced into the powder. Further nitriding occurred during sintering in a nitrogen atmosphere. For comparison, compacts having the same composition as an alloyed powder were produced from elemental powders mixture. Sintering-nitriding behaviour of investigated materials has been controlled by dilatometry, chemical and X-Ray phase analysis and metallography. Mechanical properties of sintered compacts were also measured.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.395-396
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• 2006

To manufacture a flange for a compressor with a relief groove by using powder metallurgy in order to prevent deformation to the compressor in operation, powder material for the flange is charged into a mold; an ablative member having a melting point lower than that of the powder material is positioned at a place where a relief groove is to be formed; the flange is formed by compressing the powder material and the ablative member; and the formed flange is sintered at a temperature between the melting point of the powder material and the ablative member so as to melt and remove the ablative member. It made according to the new method has more excellent strength and airtight property than the conventional one. It is analyzed that the ablative member is melted and penetrated into the flange structure during the sintering process, which results in improvement of the airtight property and increase of the strength.

• Nuclear Engineering and Technology
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• v.53 no.2
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• pp.583-591
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• 2021

Various compositions of CeO₂-Ce₃Si₂ (0, 10, 30, 50, and 100 wt%Ce₃Si₂) composites were fabricated using conventional sintering and spark plasma sintering. Lower relative density, enhanced interdiffusion of oxygen and silicon, and silicide agglomerations from the congruent melting of Ce₃Si₂ at 1390 ℃ were only observed from conventionally-sintered pellets. Thermal conductivity of spark plasma sintered CeO₂-Ce₃Si₂ composites was calculated from the measured thermal diffusivity, specific heat, and density, which exhibited dense (>90 %TD) and homogeneous microstructure. The composite with 50 wt%Ce₃Si₂ exhibited 55% higher thermal conductivity than CeO₂ at 500 ℃, and 81% higher at 1000 ℃.

• Journal of Magnetics
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• v.9 no.1
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• pp.9-12
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• 2004

We have investigated sintering effects on Fe/Mo ordering and magnetoresistance (MR) in double perovskite-reflection lines due to $Sr_2FeMoO_6$ (SFMO). Polycrystalline samples have been prepared by the conventional solid-state reaction by sintering in a stream of 5% $H_2/Ar$ gas. All samples are single phase and exhibit a series of superstructurecation ordering at Fe and Mo sites. As sintering temperature increases from 900 to $1300^{\circ}C$, the degree of Fe/Mo ordering increases from 82 to 92%, magnetization (15 K, 7 kOe) increases from 1.6 to 2.7 ${\mu}_B/f.u.,$ and Curie temperature increases at a rate of 4.3 K/% with the increase of Fe/Mo ordering ratio. The magnitude of MR measured at 5 K is 19% for sample prepared at $1000^{\circ}C$ with magnetic fields of 7 kOe. The observed MR is proportional to the square of magnetization indicating that the MR feature in SFMO is explained by the spin-polarized tunneling at grain boundaries.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.04b
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• pp.60-63
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• 2000

The $0.94MgTiO_3-0.06SrTiO_3$ ceramics were prepared by the conventional mixed oxide method. The structural properties were investigated with sintering temperature and composition ratio by XRD, SEM and DT-TGA. According to the X-ray diffraction patterns of the $0.94MgTiO_3-0.06SrTiO_3$ ceramics, the cubic $SrTiO_3$ and hexagonal $MgTiO_3$ structures were coexisted. Increasing the sintering temperature from $1325^{\circ}C$ to $1400^{\circ}C$, average grain size was increased from $5.026{\mu}m$ to $8.377{\mu}m$. In the case of the $0.94MgTiO_3-0.06SrTiO_3$ ceramics sintered at $1325^{\circ}C$, dielectric constant, quality factor and temperature coefficient of resonant frequency were 21.66, 2,522(at 7.34GHz), $+71ppm/^{\circ}C$, respectively.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.5
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• pp.533-538
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• 2011

A plastic-compatible low-temperature metal deposition and patterning process is essential for the fabrication of flexible electronics because they are usually built on a heat-sensitive flexible substrate, for example plastic, fabric, paper, or metal foil. There is considerable interest in solution-processible metal nanoparticle ink deposition and patterning by selective laser sintering. It provides flexible electronics fabrication without the use of conventional photolithography or vacuum deposition techniques. We summarize our recent progress on the selective laser sintering of metals and metal oxide nanoparticles on a polymer substrate to realize flexible electronics such as flexible displays and flexible solar cells. Future research directions are also discussed.

• Journal of Powder Materials
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• v.21 no.2
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• pp.102-107
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• 2014

A high temperature dilatometer attached to a graphite furnace is built and used to study the sintering behavior of $B_4C$. Pristine and carbon doped $B_4C$ compacts are sintered at various soaking temperatures and their shrinkage profiles are detected simultaneously using the dilatometer. Carbon additions enhance the sinterability of $B_4C$ with sintering to more than 97% of the theoretical density, while pristine $B_4C$ compacts could not be sintered above 91% due to particle coarsening. The shrinkage profiles of $B_4C$ reveal that the effect of carbon on the sinterability of $B_4C$ can be seen mostly below $1950^{\circ}C$. The high temperature dilatometer delivers very useful information which is impossible to obtain with conventional furnaces.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.10
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• pp.608-612
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• 2016

In this study, in order to develop relaxor ferroelectric ceramics for refrigeration device application with large electrocaloric effect and low sintering temperature, PLZT(8/65/35) ceramics was fabricated using conventional solid-state method with the variation of sintering temperature ($1,050^{\circ}C$, $1,100^{\circ}C$, $1,200^{\circ}C$). The XRD pattern of all specimens indicated general perovskite structure with secondary phase. From the results of temperature dependence of dielectric constant, the $T_C$ (ferroelectric-paraelectric phase transition temperature) was shifted toward high temperature with increasing sintering temperature. When the specimen was sintered at $1,100^{\circ}C$, the optimal value of ${\Delta}T{\sim}0.349^{\circ}C$ in ambient temperature of $215^{\circ}C$ was appeared. It is considered that PLZT(8/65/35) ceramics possess the possibility of refrigeration device application.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05c
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• pp.88-92
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• 2002

$Ba(Zn_{0.8}Co_{0.2})_{1/3}Ta_{2/3}O_3$ [BZCT(80/20)] ceramics were prepared by the conventional mixed oxide method. The ceramics were sintered at the temperature of $1450{\sim}1550^{\circ}C$ for 5hr. in air. The structural properties of BZCT(80/20) ceramics were investigated as a function of sintering temperature. The BZCT(80/20) ceramics sintered at $1550^{\circ}C$ showed a polycrystalline complex perovskite structure without second phases and any unreacted materials. Increasing the sintering temperature, the bulk density and ordering were increased. The bulk density of the BZCT(80/20) ceramics sintered at $1550^{\circ}C$ was 7.50[$g/cm^2$]. Increasing the sintering temperature, the average grain size were increased and pore were decreased.