• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.7
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• pp.404-407
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• 2016

In this study, to develop low temperature sintering capacitor composition ceramics with the good dielectric properties, $(Ba_{0.86}Ca_{0.14})(Ti_{0.85}Zr_{0.12}Sn_{0.03})O_3$ (BCTZ) ceramics were prepared by the conventional solid-state reaction method. The effects of $B_2O_3$ addition on the dielectric properties and microstructure was investigated. The XRD patterns demonstrated that all the specimens showed Perovskite phase, and secondary phases are indicated in the measurement range of XRD. And also, temperature coefficient of capacitance(TCC) of all the specimen sintered at $1,180^{\circ}C$ showed +3~-56% except for x=0.006. For all the specimens, observed one peak was tetragonal cubic difuse phase transition temperature(Tc), which is located in the vicinity of room temperature.

• Journal of Powder Materials
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• v.24 no.2
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• pp.115-121
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• 2017

In this work, p-type Bi-Sb-Te alloys powders are prepared using gas atomization, a mass production powder preparation method involving rapid solidification. To study the effect of the sintering temperature on the microstructure and thermoelectric properties, gas-atomized powders are consolidated at different temperatures (623, 703, and 743 K) using spark plasma sintering. The crystal structures of the gas-atomized powders and sintered bulks are identified using an X-ray diffraction technique. Texture analysis by electron backscatter diffraction reveals that the grains are randomly oriented in the entire matrix, and no preferred orientation in any unique direction is observed. The hardness values decrease with increasing sintering temperature owing to a decrease in grain size. The conductivity increases gradually with increasing sintering temperature, whereas the Seebeck coefficient decreases owing to increases in the carrier mobility with grain size. The lowest thermal conductivity is obtained for the bulk sintered at a low temperature (603 K), mainly because of its fine-grained microstructure. A peak ZT of 1.06 is achieved for the sample sintered at 703 K owing to its moderate electrical conductivity and sustainable thermal conductivity.

• Journal of the Korean Ceramic Society
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• v.48 no.6
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• pp.641-647
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• 2011

The present study aims to identify the effect of sintering atmosphere [$O_2$, 75$N_2$-25 $H_2$ (mol%) and $H_2$] on microstructural evolution at the relatively low sintering temperature of 1040$^{\circ}C$. Samples sintered in $O_2$ showed a bimodal microstructure consisting of fine matrix grains and large abnormal grains. Sintering in 75 $N_2$ - 25 $H_2$ (mol %) and $H_2$ caused the extent of abnormal grain growth to increase. These changes in grain growth behaviour are explained by the effect of the change in step free energy with sintering atmosphere on the critical driving force necessary for rapid grain growth. The results show the possibility of fabricating $(K_{0.5}Na_{0.5})NbO_3$ at low temperature with various microstructures via proper control of sintering atmosphere.

• Electrical & Electronic Materials
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• v.1 no.1
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• pp.26-34
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• 1988

Sintered CdS/CdTe solar cells have been farbricated by coating a (Cd+Te) slurry on sintered CdS films followed by the sintering at 625.deg.C for one hour with various heating rates. When cadmium and tellurinm powders are used instead of CdTe powder to form CdS/CdTe junction, CdTe is formed in the temperature range of 290.deg.C-400.deg.C. The microstructure of the CdTe films depends strongly on the heating rate of the sintering due to the low melting temperature and the high vapor pressure of the elemental Cd and Te. An optimum heating rate obtain CdTe films with uniform and dense microstructure which, in turn, improves the efficiency of the sintered CdS/CdTe solar cells. All-polycrystalline CdS/CdTe solar cells with an efficiency of 9.57% under 50mW/cm$^{2}$ tungsten light have been farbricated by using a heating rate of 14.deg.C/min.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.657-661
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• 2002

PZT powder was prepared by partial oxalate method using $(Zr_{0.53}Ti_{0.47})O_2$, $Pb(NO_3)_2$ and $(COOH)_2{\cdot}2H_2O$ as a precipitant. $Nb_2O_5$ additive effect on microstructure and piezoelectric properties of PZT ceramics were investigated. The coexistence of rhombohedral and tetragonal phases of PZT ceramics at the sintering temperature of $1100^{\circ}C$ was revealed from the X-ray diffraction patterns. The grain size PZT ceramics was decreased with the increase $Nb^{5+}$. and the sinterbility of PZT ceramics was decreased with the increase $Nb^{5+}$ addition. The electromechanical coupling factors $K_p$ show above 0.60 at $1100^{\circ}C$ sintering temperature by $Nb_2O_5$ addition above 0.6mol%.

• Journal of Powder Materials
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• v.10 no.4
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• pp.270-274
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• 2003

Recently, the fabrication process of W-Cu nanocomposite powders has been researched to improve the sinterability by mechanochemical process (MCP), which consists of ball milling and hydrogen-reduction with W- and Cu-oxide mixture. However, there are many control variables in this process because the W oxides are hydrogen-reduced via several reduction stages at high temperature over 80$0^{\circ}C$ with susceptive reduction conditions. In this experiment, the W-15 wt%Cu nanocomposite powder was fabricated with the ball-milling and hydrogen-reduction process using W and CuO powder. The microstructure of the fabricated W-Cu nanocomposite powder was homogeneously composed of the fine W particles embedded in the Cu matrix. In the sintering process, the solid state sintering was certainly observed around 85$0^{\circ}C$ at the heating rate of 1$0^{\circ}C$/min. It is considered that the solid state sintering at low temperature range should occur as a result of the sintering of Cu phase between aggregates. The specimen was fully densified over 98% for theoretical density at 120$0^{\circ}C$ for 1 h with the heating rate of 1$0^{\circ}C$/min.

• Journal of the Korean Recycled Construction Resources Institute
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• v.10 no.3
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• pp.211-218
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• 2022

Coal ash is being considered as a source of silica and alumina for cement clinker. The purpose of this study was to investigate the effect on cement clinker sintering by confirming the high-temperature microstructural change according to the firing temperature in the cement clinker sintering process of coal ash. In the coal ash used as a raw material for cement clinker, the shape change of the particle surface was confirmed from the sintering tem perature of 950 ℃. The shape of the coal ash disappeared from the sintering temperature higher than 1250 ℃. It was confirmed that the Al and Fe components of the coal ash were converted to the cement interstitial phase at a temperature higher than 1350 ℃. In addition, the clinker using a large amount of coal ash as a raw material showed a low content of Lime and a high content of Belite in the sintering tem perature range of 1150~1200 ℃. From this, it was confirmed that the formation of calcium silicate mineral proceeds more easily at the initial sintering temperature by the application of coal ash.

• Journal of the Korean Ceramic Society
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• v.36 no.5
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• pp.490-496
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• 1999

The sintering behavior of LTCC (low temperature cofired ceramics) chip couplers was investigated in relation with Ag diffusion at the interface of glass ceramic substrate-Ag electrode. Sintering temperature was in the range of 825$^{\circ}C$-975$^{\circ}C$. The commercial green sheet and silver electrode were used. Below 875$^{\circ}C$ the diffusion of the Ag ion into the substrate and the penetration of glassy phases into the electrode occurred due to an increase of fluidity. Thus the lectrode line was severely deformed and damaged. At 975$^{\circ}C$ the transformation of crystalline phases into glassy phases and the melting of the Ag electrode resulted in the diffusion of the considerable amount of Ag ions.

• Journal of Powder Materials
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• v.29 no.5
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• pp.357-362
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• 2022

The low-temperature sinterability of TiO₂-CuO systems was investigated using a solid solution of SnO₂. Sample powders were prepared through conventional ball milling of mixed raw powders. With the SnO₂ content, the compositions of the samples were Ti_1-xSn_xO₂-CuO(2 wt.%) in the range of x ≤ 0.08. Compared with the samples without SnO₂ addition, the densification was enhanced when the samples were sintered at 900℃. The dominant mass transport mechanism seemed to be grain-boundary diffusion during heat treatment at 900℃, where active grain-boundary diffusion was responsible for the improved densification. The rapid grain growth featured by activated sintering was also obstructed with the addition of SnO₂. This suggested that both CuO as an activator and SnO₂ dopant synergistically reduced the sintering temperature of TiO₂.

• Journal of Powder Materials
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• v.28 no.5
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• pp.403-409
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• 2021

In this study, Ti-Mo-EB composites are prepared by ball milling and spark plasma sintering (SPS) to obtain a low elastic modulus and high strength and to evaluate the microstructure and mechanical properties as a function of the process conditions. As the milling time and sintering temperature increased, Mo, as a β-Ti stabilizing element, diffused, and the microstructure of β-Ti increased. In addition, the size of the observed phase was small, so the modulus and hardness of α-Ti and β-Ti were measured using nanoindentation equipment. In both phases, as the milling time and sintering temperature increased, the modulus of elasticity decreased, and the hardness increased. After 12 h of milling, the specimen sintered at 1000℃ showed the lowest values of modulus of elasticity of 117.52 and 101.46 GPa for α-Ti and β-Ti, respectively, confirming that the values are lower compared to the that in previously reported studies.