• Title/Summary/Keyword: Microwave sintering

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Structural and Microwave Dielectric Properties of the $0.94MgTiO_3-0.06SrTiO_3$ Ceramics with Sintering Temperature (소결온도에 따른 $0.94MgTiO_3-0.06SrTiO_3$ 세라믹스의 구조 몇 마이크로파 유전특성)

  • Choi, Eui-Sun;Lee, Moon-Kee;Park, In-Gil;Ryu, Ki-Won;Lee, Young-Hie
    • 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.

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Microwave Sintering of FLY Ash Substituted Body and Numerical Analysis

  • Kim, S. B.;J. W. Han;Kim, Y.
    • Proceedings of the Korea Association of Crystal Growth Conference
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    • 1998.06a
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    • pp.75-76
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    • 1998
  • Fly ash 70wt% contained green bodies were sintered by using a 2.45 Ghz microwave oven and their properties were investigated. Samples were sintered at 1,150$^{\circ}C$ and kept at that temperature up 50 minutes by 10 minutes intervals. Numerical analysis on the microwave heated system was carried out in order to figure out the heat transfer phenomena in the cavity.

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Tailored Powder Composites by Freeze Drying, Electrophoretic Deposition and Sintering

  • Olevsky, Eugene A.;Wang, Xuan
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • 2006.09a
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    • pp.287-288
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    • 2006
  • Two approaches for the fabrication of tailored powder composites with specially distributed pore-grain structure and chemical composition are investigated. Electrophoretic Deposition (EPD) followed by microwave sintering is employed to obtain functionally graded materials (FGM) by in-situ controlling the deposition bath suspension composition. $Al_2O_3/ZrO_2$ and zeolite FGM are successfully synthesized using this technique. In order to fabricate an aligned porous structure, unidirectional freezing followed by freeze drying and sintering is employed. By controlling the temperature gradient during freezing of powder slurry, a unidirectional ice-ceramic structure is obtained. The frozen specimen is then subjected to freeze drying to sublimate the ice. The obtained capillary-porous ceramic specimen is consolidated by sintering. The sintering of the graded structure is modeled by the continuum theory of sintering.

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A Study on Frequency and the Physical Properties of Ni-Cu-Zn Ferrites with the Variation of Ni Addition and Temperature Prepared by Co-Precipitation Method (공침법으로 제조한 Ni-Cu-Zn Ferrite의 Ni 첨가량과 온도에 따른 주파수 및 물리적 특성 연구)

  • Kim, Moon-Suk;Koh, Jae-Gui
    • Journal of the Korean Magnetics Society
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    • v.15 no.5
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    • pp.282-286
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    • 2005
  • Ni-Cu-Zn ferrites were prepared by the co-precipitation and ferrite microwave absorbers on low temperature sintering were investigated in this work. The properties of its microwave absorbing and physical were analyzed into variations of Ni addition, calcination temperature, sintering temperature. From the analysis of X-ray diffraction patterns, we can see that all the particles have only a single phase spinel structure. In addition, the powders particle size distribution obtained the nano size. By increasing the Ni additive, the permeability of the powders was decreased and the loss factor increased at sintering temperature $1100^{\circ}C$. Also, we considered that it can used high frequency rage. We found that the $(Ni_{0.7}Cu_{0.2}Zn_{0.1}O)_{1.02}(Fe_{2}O_3)_{0.98}$ appeared microwave absorbing properties better than other composition.

Structural and Microwave Dielectric Properties of the $0.9MgTiO_3-0.1SrTiO_3$ Ceramics with Sintering Temperature (소결온도에 따른 $0.9MgTiO_3-0.1SrTiO_3$ 세라믹스의 구조 및 마이크로파 유전특성)

  • Choe, Ui-Seon;Lee, Mun-Gi;Ryu, Gi-Won;Bae, Seon-Gi;Lee, Yeong-Hui
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.49 no.5
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    • pp.294-298
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    • 2000
  • The $MgTiO_3\; and \;$0.9MgTiO_3-0.1SrTiO_3$ ceramics were fabricated by the conventional mixed-oxide method. The sintering temperature and time were $1300^{\circ}C~1600^{\circ}C$, 2hr., respectively. The structural and microwave dielectric properties were investigated with sintering temperature and the application for the satellite communication microwave dielectric resonator was investigated. The coexistence of cubic $SrTiO_3$ and hexagonal TEX>$MgTiO_3$ structures in $0.9MgTiO_3-0.1SrTiO_3$ ceramics were found from X-ray diffraction patterns. In the case of $MgTiO_3$ ceramics, sphere phase and needle-like phase were coexisted. The $0.9MgTiO_3-0.1SrTiO_3$ ceramics observed sphere phase. The dielectric constants and temperature coefficient of resonant $frequency(\tauf)$ were increased with addition of $SrTiO_3$ but the quality factor was decreased. The dielectric constant, quality factor and $\tau$f of the;$0.9MgTiO_3-0.1SrTiO_3$ ceramics were 22.61, 10.928(at 1GHz) and $+50.26ppm/^{\circ}C$, respectively.

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Microwave Dielectric Properties of Ca[($Li_{1/3}Nb_{2/3}$)$_{1-x}$$Ti_{x}$]$O_{3-{\delta}}$ with $Bi_2O_3$ Additives ($Bi_2O_3$ 첨가에 의한 Ca[($Li_{1/3}Nb_{2/3}$)$_{1-x}$$Ti_{x}$$O_{3-{\delta}}$ 세라믹스의 마이크로파 유전 특성)

  • 하종윤;최지원;이동윤;윤석진;최두진;김현재
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2002.07a
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    • pp.131-134
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    • 2002
  • The effect of the addition on the densification, low temperature sintering, and microwave dielectric properties of the Ca[($Li_{1/3}Nb_{2/3}$)$_{1-x}$$Ti_{x}$]$O_{3-{\delta}}$/(CLNT) was investigated. $Bi_2O_3$ additives improved the dencification and reduced the sintering temperature from $1150^{\circ}C$ to $900^{\circ}C$ of CLNT microwave dielectric ceramics. As increasing $Bi_2O_3$ contents, the dielectric constants and bulk density were increased. The quality factor, however, was decreased slighty. The temperature coefficients of the resonant frequency shifted positive value as increasing $Bi_2O_3$ contents. The dielectric properties of Ca[($Li_{1/3}Nb_{2/3}$)$_{1-x}$$Ti_{x}$]$O_{3-{\delta}}$ and Ca[($Li_{1/3}Nb_{2/3}$)$_{0.8}Ti_{0.2}$]$O_{3-{\delta}}$ with 5wt% $Bi_2O_3$ sintered at $900^{\circ}C$ for 3h were $\varepsilon_{r}$=20, 35 Q.$f_{0}$=6500, 11,000 GHz, $\tau_{f}$=4, 13 ppm/$^{\circ}C$, respectively.

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The Microwave Dielectric Properties of Bi0.97Tm0.03NbO4 Doped with V2O5 (마이크로파 유전체 Bi0.97Tm0.03NbO4의 V2O5 첨가에 따른 유전특성)

  • 황창규;장건익;윤대호
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.16 no.11
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    • pp.975-978
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    • 2003
  • The microwave dielectric properties and the microstructures on B $i_{0.97}$T $m_{0.03}$Nb $O_4$ doped with $V_2$ $O_{5}$ were systematically investigated. B $i_{0.97}$T $m_{0.03}$Nb $O_4$ ceramics sintered at 920-96$0^{\circ}C$ were mainly consisted of orthorhombic and triclinic phases after addition of $V_2$ $O_{5}$. The apparent density increased slightly with increasing the $V_2$ $O_{5}$ addition. The dielectric constants($\varepsilon$$_{r}$) also increased with $V_2$ $O_{5}$ addition(30-45). The Q${\times}$ $f_{0}$ values measured on B $i_{0.97}$T $m_{0.03}$Nb $O_4$ ceramics doped with $V_2$ $O_{5}$ were between 2,000 and 12,000[GHz] when the sintering temperatures were in the range of 920-960[$^{\circ}C$]. It was confirmed that the temperature coefficient of the resonant frequency($\tau$$_{f}$) can be adjusted from a positive value of +10ppm/$^{\circ}C$ to a negative value of -15ppm/$^{\circ}C$ by increasing the amount of $V_2$ $O_{5}$ Based on our experimental results, the B $i_{0.97}$T $m_{0.03}$Nb $O_4$(added $V_2$ $O_{5}$) ceramics can be applied to multilayer microwave devices at low sintering temperatures.ng temperatures.emperatures.ratures.

The microwave dielectric properties of $Bi_{0.97}Tm_{0.03}NbO_{4}$ doped with $V_{2}O_{5}$ (마이크로파 유전체 $Bi_{0.97}Tm_{0.03}NbO_{4}$$V_{2}O_{5}$ 첨가에 따른 유전특성)

  • Hwang, Chang-Gyu;Jang, Gun-Eik
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2002.11a
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    • pp.350-353
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    • 2002
  • The microwave dielectric properties and the microstructures on $Bi_{0.97}Nb_{0.03}O_{4}$doped with $V_{2}O_{5}$ were systematically investigated. $Bi_{0.97}Tm_{0.03}Nb_{0.03}O_{4}$ ceramics sintered at $920-960^{\circ}C$were mainly consisted of orthorhombic and triclinic phases after addition of $V_{2}O_{5}$. The apparent density increased slightly with increasing the $V_{2}O_{5}$ addition. The dielectric $constants(\varepsilon_r)$ also increased with $V_{2}O_{5}$ addition(30-45). The $Q{\times}f_0$ values measured on $Bi_{0.97}Tm_{0.03}NbO_4$ ceramics doped with $V_{2}O_{5}$ were between 2,000 and 12,000[GHz] when the sintering temperatures are in the range of $920-960[^{\circ}C]$. It was confirmed the temperature coefficient of the resonant $frequency(\tau_f)$ can be adjusted from a positive value of $+10[ppm/^{\circ}C]$ to a negative value of $-15ppm/^{\circ}C$ by increasing the amount of $V_{2}O_{5}$. Based on our experimental results, the Bi0.97Tm0.03NbO4(added V2O5) ceramics can be applied to multilayer microwave devices at low sintering temperatures.

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Microstructure and Microwave Dielectric Properties of (1-x) Ba (Co1/3Nb2/3)O3-zBa(Zn1/3Nb2/3)O3 Ceramics

  • Ahn, Byung-Guk;Ahn, Cheol-Woo;Nahm, Sahn;Lee, Hwack-Joo
    • Journal of the Korean Ceramic Society
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    • v.40 no.4
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    • pp.333-339
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    • 2003
  • Ba (Co$_{1}$ 3/Nb$_{2}$ 3/)O$_3$(BCN) has a 1:2 ordered hexagonal structure. Q-value of BCN increased with increasing sintering temperature however, it significantly decreased when the sintering temperature exceeded 140$0^{\circ}C$ Ba (Co$_{1}$ 3/Nb$_{2}$ 3/)O$_3$(BZN) has the 1:2 ordered hexagonal structure and the degree of the 1 : 2 ordering decreased with the increase of the sintering temperature. The Q value of the BZN increased with increasing the sintering temperature and BZN sintered at 140$0^{\circ}C$ for 6h has a maximum Q-value. For (1-x) Ba (Co$_{1}$ 3/Nb$_{2}$ 3/)O$_3$-zBa(Zn$_{1}$ 3/Nb$_{2}$ 3/)O$_3$[(1-x)BCN-xBZN] ceramics the 1:2 ordered hexagonal structure was observed in the specimens with x$\leq$0.3 and the BaNb$_{6}$ O$^{16}$ second phase was found in the specimens with x$\geq$0.6. Grain Growth, which is rotated to the BaNb$_{6}$ O$^{16}$ second phase occurred in the specimens with x$\geq$ 0.5. In this work, the excellent microwave dielectric properties of $\tau$r=0.0 ppm/$^{\circ}C$$\varepsilon$r=34.5 and Q,$\times$f=97000GHz sere obtained for the 0.7BCV-0.3BZN ceramics sintered at 1400$0^{\circ}C$ for 20h.

Microwave Dielectric Properties of CaTi0.5Fe0.25Nb0.25O3 Ceramics with CuO Addition

  • Kang, Kui-Won;Kim, Hyo-Tae;Hwang, Joon-Cheol;Nam, Joong-Hee;Yeo, Dong-Hun
    • Journal of the Korean Ceramic Society
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    • v.41 no.8
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    • pp.633-636
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    • 2004
  • The sintering behavior, microstructure and microwave dielectric properties of Ca $Ti_{0.5}$F $e_{0.25}$N $b_{0.25}$ $O_3$ with CuO have been investigated. Among the range of additions, 3 wt% CuO was observed to perform most satisfactory for acting as a sintering aid. The dielectric properties were found to strongly depend on the sintered densities. The dielectric constant increased with sintering temperatures, while the Q${\times}$ $f_{0}$ value affected by second phase. For Ca $Ti_{0.5}$F $e_{0.25}$N $b_{0.25}$ $O_3$ with 3 wt% CuO sintered at 100$0^{\circ}C$ for 2 h, the dielectric properties with an $\varepsilon$$_{r}$ value of 56, a Q${\times}$ $f_{0}$ value of 3,500 GHz and a $\tau$$_{f}$ value of 10 ppm/$^{\circ}C$ were obtained and suggested for practical applications.cations.ons.ons.ons.