• Title/Summary/Keyword: 소결분말

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Preparation of PZT Powders by Hydrothermal Synthesis : Effects of Starting Materials and the Agitation of Substrate on Powder Characteristics (수열합성법에 의한 PZT 분말제조 : 출발물질과 기질의 교반이 분말특성에 미치는 영향)

  • Jung, S.T.;Lee, K.J.;Seo, K.W.
    • Applied Chemistry for Engineering
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    • v.8 no.2
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    • pp.292-300
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    • 1997

  • In this study PZT powders were prepared with shapes of cubic by hydrothermal synthesis with various starting materials, and the sintering characteristics of the powders were investigated. The particle shapes were cubic regardless of starting materials, but the mean size of particles formed using $Pb(NO_3)_2$, $Ti(OC_4H_9)_4$ and $Zr(OC_4H_9)_4$ was relatively smaller than that of particles prepared from other starting materials. Agitation of the feedstock during hydrothermal reaction results in decreasing the required reaction temperature for the formation of nuclei, and in increasing the size of product particles. XRD results showed that the major phase of PZT crystal powders was a tetragonal phase at the Zr to Ti ratio of 40 to 60, or a rhombohedral phase at its ratio of 60 to 40. The density of a sintered body made from the hydrothermal powders in PbO surrounding varied with sintering temperatures and with periods of sintering time. The experimental results also showed that the optimum sintering condition was at $1150^{\circ}C$ for a 2hr sintering, and that the density of a sintered body was $7.6g/cm^3$.

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Microstructural evolution in liquid-phase sintered $\alpha$-silicon carbide (액상소결 $\alpha$형 탄화규소의 미세구조 변화)

  • 이종국;강현희;박종곤;이은구
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.8 no.2
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    • pp.324-331
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    • 1998

  • After the addition of yttrium aluminum garnet of 2, 5, 10 mol% as a sintering aid, $\alpha$-silicon carbides were prepared by a liquid-phase sintering at $1850^{\circ}C$, and the microstructural evolution was investigated during sintering as functions of liquid-phase amount and sintering time. The highest apparent density in each compositions was obtained in specimens sintered for 2 h, and the percentage of weight loss increased with sintering time. By increasing the amount of sintering aid (yttrium aluminum garnet), the rate of grain growth during sintering decreased, but the apparent density of sintered body increased. The phase transformation from 6H-SiC to 4H-SiC was partially observed in specimens sintered for a long time, and so, a few rod-like grains were observed.

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