• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.214-215
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• 2005

In this paper, in order to develop low temperature sintering piezoelectric ceramics for piezoelectric transformer, PMW-PMN-PZT ceramics using 0.25wt%$CaCO_3$ and 0.2wt%$Li_2CO_3$ as sintering aids were fabricated according to the variation of amount of PMW and Zr/Ti ratio. Specimens could be sintered at 900$^{\circ}C$ by adding sintering aids. As Zr/Ti ratio was increased, kp was increased and Qm was decreased by approaching MPB region, and kp showed the largest value of 0.58 at Zr/Ti:50/50. The variation of amount of PMN substitution affected the liquid phase sintering of the ceramics using sintering aids, and decreased piezoelectric properties.

• Journal of Powder Materials
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• v.17 no.3
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• pp.235-241
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• 2010

Mo nanopowder was synthesized by ball-milling and subsequent hydrogen-reduction of $MoO_3$ powder. To fabricate ultra fine grained molybdenum, two-step sintering and spark plasma sintering process were employed. The grain size of specimen by two-step sintering and spark plasma sintering was around $0.6\;{\mu}m$ and $0.4\;{\mu}m$, respectively. Mechanical properties of ultra fine grained Mo with relative density of above 90% were significantly improved at room and high temperatures comparing to commercial bulk Mo of 99% relative density. This result was mainly explained by the grain size refinement due to diffusion-controlled sintering.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.11
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• pp.875-879
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• 2010

In this study, we have characterized the roles of $Cr_2O_3$ on the sintering and electrical properties of ZnO. The densification and grain growth of Cr-doped ZnO (ZCr) system was mainly influenced by Cr contents. In the beginning of sintering, the densification of ZnO was retarded as reducing the Zni concentration in ZnO lattice with Cr doping. And the densification and grain growth of ZnO was more retarded due to a formation of spinel phase with increasing the Cr contents. ZCr system revealed varistor behavior with nonlinear coefficient $\alpha$ of 3~23 depending on the sintering temperature, implying double Schottky barrier formation on the grain boundary of ZnO. Especially the best varistor characteristics should be developed with 0.1~0.5 at% Cr contents and under $1100^{\circ}C$ in ZCr systems.

• Journal of Powder Materials
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• v.21 no.2
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• pp.137-141
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• 2014

In this study, we report the sintering behavior and properties of a $Ge_2Sb_2Te_5$ alloy powders for use as a sputtering target by spark plasma sintering. The effect of various sintering parameters, such as pressure, temperature and time, on the density and hardness of the target has been investigated in detail. Structural characterization was performed by scanning electron microscopy and X-ray diffraction. Hardness and thermal properties were measured by differential scanning calorimetry and micro-vickers hardness tester. The density and hardness of the sintered $Ge_2Sb_2Te_5$ materials were 5.8976~6.3687 $g/cm^3$ and 32~75 Hv, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.693-696
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• 2001

The (Ba$_{0.3}$Bi$_{0.3}$Sr$_{0.4}$)TiO$_3$[BBST] ceramics were prepared by conventional mixed oxide method. The structural properties of the BBST ceramics with sintering temperature were investigated by XRD, SEM, EDS. In the case of BBST ceramics sintered at 1150~135$0^{\circ}C$, the $Ba_{0.5}$Sr$_{0.5}$TiO$_3$and SrBi$_4$Ti$_4$O$_{15}$ phase were coexisted. The 2$\theta$ value of the BST (110) peaks were shifted to the lower degree at the sintering temperature of 130$0^{\circ}C$ and 135$0^{\circ}C$. The grains of the BBST ceramics sintered at 130$0^{\circ}C$ and 135$0^{\circ}C$ were not appeared. Increasing the sintering temperature, the densities of the BBST ceramics were increased. In the BBST ceramics sintered at 130$0^{\circ}C$ and 135$0^{\circ}C$, the mole ratio of Bi was decreased.d.ed.d.d.d.

• Journal of Sensor Science and Technology
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• v.27 no.4
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• pp.249-253
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• 2018

Infrared transparent ZnS ceramics were synthesized through hydrothermal synthesis ($180^{\circ}C$, 70 h) and sintered using a hot press process at $750^{\circ}C-1000^{\circ}C$. We carried out x-ray diffraction, scanning electron microscopy, and Fourier transform-infrared spectroscopy to confirm the optical properties of the ZnS ceramics after sintering at various temperatures. The phase of ZnS nanopowders was a single phase (cubic) without the hexagonal phase. However, as sintering temperature increased, the formation and increment of hexagonal structures was confirmed. The ZnS ceramic sintered at a temperature of $750^{\circ}C$ showed poor transmittance because it was not completely sintered and because of the pore effect. The ZnS ceramic with the highest transmittance (approximately 69%) was sintered at $800^{\circ}C$. As sintering temperature increased, transmittance gradually decreased owing to the increase in the formation of the hexagonal phase.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.196-197
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• 2005

The $ZnNb_2O_6$ ceramics with 3wt% CuO and $B_2O_2$(1,3,5wt%) were prepared by the conventional mixed oxide method. The ceramics were sintered at the temperature of $1000^{\circ}C\sim1050^{\circ}C$ 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. But no significant difference was observed as sintering temperature. In the $ZnNb_2O_6$ ceramics with 3wt% CuO and 5wt% $B_2O_3$ sintered at $1025^{\circ}C$ for 3hr, the dielectric constant, quality factor, temperature coefficient of the resonant frequency were 22.92, 20,271GHz, -14.27ppm/$^{\circ}C$, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1994.11a
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• pp.8-12
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• 1994

Solid solutions $Sr_2$($Ta_{1-x}$$Nb_{x}$)$_2$$O_{7}$ (x = 0.0 - 1.0) composed of strontium-tantalate (low Curie temperature) and strontium-niobate (high Curie temperature) were prepared by the conventional mixed oxide method and the molten salt synthesis method (flux method). Phase relation, sintering temperature, grain-orientation and dielectric properties were investigated for sintered ceramic samples with different compositions. Both Curie temperature and dielectric constant at Curie temperature were increased, and sintering behavior and the degree of grain-orientation were improved with the increase of Nb content. Single phase $Sr_2$$Nb_2$$O_{7}$ powder was synthesized by using flux method at lower temperatures, and sintering temperature was also reduced by using flux method derived powder than using mixed-oxide derived powder. Sintering characteristics and dielectric properties of specimens prepared by flux method were better than those derived through the conventional method.

• Transactions of Materials Processing
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• v.29 no.5
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• pp.251-256
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• 2020

The purpose of this study is to investigate the effect of sintering condition on the microstructure evolution and tensile properties of the Ti-6Al-4V alloy sample processed by metal injection molding (MIM) in terms of the sizes of the alpha morphology and pore found in the matrix. For this purpose, a series of MIM were conducted on this sample at various sintering temperatures ranging from 1173 to 1373 K for three hours followed by furnace cooling, observed by the scanning electron microscopy. The microstructures sintered in this study showed that, with increasing sintering temperature over beta transus temperature, the transformation of the equiaxed alpha into transformed beta was attained while the size of pores would tend to decrease. Thus, the strength remained unchanged significantly in the tension while ductility increased to some extent as sintering temperature increased. Such mechanical behavior would be explained in relation to the microstructure evolution of the Ti-6Al-4V sample via the MIM.

• Korean Journal of Materials Research
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• v.19 no.12
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• pp.686-691
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• 2009

The effects of thermal properties on the crystallization behavior of $CaMgSi_2O_6$ glass-ceramics were investigated as a function of sintering temperature from 800$^{\circ}C$ to 900$^{\circ}C$. The crystallization behavior of the specimens depended on the sintering temperature, which could be evaluated from the differential thermal analysis, X-ray diffraction and Fourier transform infrared spectroscopy. With increasing sintering temperature, the thermal conductivity of the sintered specimens increased, while the coefficient of thermal expansion (CTE) of the sintered specimens decreased. These results could be attributed to the increase of crystallization, confirmed from the estimation by density measurements. Also, the thermal diffusivity and specific heat capacity of the sintered specimens were discussed with relation to the sintering temperature. Typically, a thermal conductivity of 3.084 $W/m^{\circ}C$, CTE of 8.049 $ppm/^{\circ}C$, thermal diffusivity of 1.389 $mm^2/s$ and specific heat capacity of 0.752 $J/g^{\circ}C$ were obtained for $CaMgSi_2O_6$ specimens sintered at 900$^{\circ}C$ for 5 h.