• Title/Summary/Keyword: sintering at low temperature sintered properties

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Phase stability and Sintered Properties of 1.5mol% Yttria-stabilized Zirconia Ceramics Fabricated by Low Temperature Sintering (저온 열처리로 제작된 1.5 mol% 이트리아 안정화 지르코니아 세라믹스의 상 안정성 및 소결물성)

  • Kyung Tae Kim;Han Cheol Choe;Jeong Sik Park;Jong Kook Lee
    • Journal of the Korean Society for Heat Treatment
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    • v.37 no.1
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    • pp.1-8
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    • 2024
  • Phase stability of tetragonal crystals in yttria-stabilized zirconia ceramics is dependent on the content of yttria and the heat-treatment condition, related with mechanical properties. In this study, we fabricated the 1.5 mol% yttria-stabilized zirconia (1.5Y-YSZ) ceramics by cold isostatic pressing (CIP) and post-sintering at temperature range of 1200 to 1350℃ for 2 hours and investigated the sintered properties and microstructural evolution. Sintered and microstructural parameters, i.e, apparent density, grain size and phase composition of 1.5Y-YSZ ceramics were mainly dependent on the sintering temperature. Maximum sintered density of 99.4 % and average grain size of 200-300 nm could be obtained from the heat-treatment condition above sintering temperature at 1300℃ for 2 hours, possessing the superior mechanical hardness with 1200 Hv. However, phase stability of tetragonal grains in 1.5 YSZ ceramics is very low, inducing the phase transformation to monoclinic crystals on specimen surface during cooling after heat-treatment.

Microstructure and Electrical Properties of $RuO_2$ System Thick Film Resistors ($RuO_2$계 후막저항체의 미세구조와 전기적성질)

  • 구본급;김호기
    • Journal of the Korean Ceramic Society
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    • v.27 no.3
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    • pp.337-344
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    • 1990
  • As a function of sintering temperature and time, the electrical properties of ruthenium based thick film resistors were investigated with microstructure. The variatio of resistivity and TCR(temperature coefficient of resistance)trends of sintered speciman at various sintering temperature were different low resistivity paste(Du Pont 1721) from high one(Du Pont 1741). These phenomena are deeply relative to microstructure of sintered film. With increasing the sintering temperature for 1721 system, the electrical sheet resistivity decreased, but again gradually increased above 80$0^{\circ}C$. And TCR trends in 1721 system are all positive. On the other hand the electrical sheet resistivity of 1741 resistor system decreased with sintering temperature. And TCR trends variable according to sintering temperature. TCR of speciman sintered at $700^{\circ}C$ was negative value, and TCR of 80$0^{\circ}C$ sintered speciman coexisted negative and positive value. But in case of speciman sintered at 90$0^{\circ}C$, TCR was positive value. As results of this fact, it was well known that the charge carrier contributied to electrical conduction in 1741 resistor system varied with sintering temperature.

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PZTN Sintered at the Low Temperature by the Glass Phase Transient Processing (글래스 천이 공정에 의해 저온소결된 PZTN)

  • Kim Chan Young
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.54 no.3
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    • pp.97-102
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    • 2005
  • This research was a fundamental study for the low temperature sintering of PZTN by glass phase transient processing. To lower the sintering temperature, the glass phase Processing was used. Also to improve the electrical properties, the transient processing was utilized. After characterization, the various analytic techniques, such as Archimedes method for the measuring densification, x-ray diffraction patterns for the quantitative analysis of crystalline phases were utilized. Also the dielectric constant, dissipation factor, and piezoelectric coefficients were measured to evaluate the PZTN sintered at the $950^{\circ}C$ and $1050^{\circ}C$. This was confirmed that the sintering temperature of PZTN was reduced by $950^{\circ}C$ and the electrical properties were improved by the transition processing. Therefore, the glass phase transient processing can be applicable to low the sintering temperature with the dielectric and piezoelectric properties.

Low-Temperature Sintering of PZT+0.5wt%$MnO_2$+1wt%$B_2O_3$ ceramics (PZT + 0.5wt%$MnO_2$ + 1wt%$B_2O_3$ 세라믹스의 저온소결에 관한 연구)

  • Shin, Hyea-Kyoung;Kim, Dea-Il;Bae, Seon-Gi
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2005.07a
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    • pp.346-347
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    • 2005
  • In this study, in order to develop the low temperature sintering ceramics, PZT ceramics adding $MnO_2$, $B_2O_3$ were manufactured, and their piezoelectric and dielectric properties is investigated. The results of this study were gotten such as follows. The electromechanical coupling coefficient(kp) showed good properties on the whole, showed its maximum value 28.266 in specimens sintered at 1200[$^{\circ}C$]. The mechanical quality coefficient(Qm) showed its maximum value 162.61 in specimens sintered at 1200[$^{\circ}C$] and was increased by increasing sintering temperature. The dielectric constant showed the optimum values of 538.903 at specimen sintered at $1000^{\circ}C$.

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Effect of Low-Temperature Sintering on Electrical Properties and Aging Behavior of ZVMNBCD Varistor Ceramics

  • Nahm, Choon-Woo
    • Korean Journal of Materials Research
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    • v.30 no.10
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    • pp.502-508
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    • 2020
  • This paper focuses on the electrical properties and stability against DC accelerated aging stress of ZnO-V2O5-MnO2-Nb2O5-Bi2O3-Co3O4-Dy2O3 (ZVMNBCD) varistor ceramics sintered at 850 - 925 ℃. With the increase of sintering temperature, the average grain size increases from 4.4 to 11.8 mm, and the density of the sintered pellets decreases from 5.53 to 5.40 g/㎤ due to the volatility of V2O5, which has a low melting point. The breakdown field abruptly decreases from 8016 to 1,715 V/cm with the increase of the sintering temperature. The maximum non-ohmic coefficient (59) is obtained when the sample is sintered at 875 ℃. The samples sintered at below 900 ℃ exhibit a relatively low leakage current, less than 60 mA/㎠. The apparent dielectric constant increases due to the increase of the average grain size with the increase of the sintering temperature. The change tendency of dissipation factor at 1 kHz according to the sintering temperature coincides with the tendency of the leakage current. In terms of stability, the samples sintered at 900 ℃ exhibit both high non-ohmic coefficient (45) and excellent stability, 0.8% in 𝚫EB/EB and -0.7 % in 𝚫α/α after application of DC accelerated aging stress (0.85 EB/85 ℃/24 h).

Effects of Low-Temperature Sintering on Varistor Properties and Stability of VMCDNB-Doped Zinc Oxide Ceramics

  • Nahm, Choon-W.
    • Journal of the Korean Ceramic Society
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    • v.56 no.1
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    • pp.84-90
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    • 2019
  • The varistor properties and stability against dc-accelerated stress of $V_2O_5-Mn_3O_4-Co_3O_4-Dy_2O_3-Nb_2O_5-Bi_2O_3$ (VMCDNB)-doped zinc oxide ceramics sintered at $850-925^{\circ}C$ were investigated. Increasing the sintering temperature increased the average grain size from 4.6 to 8.7 mm and decreased the density of the sintered pellet density from 5.54 to $5.42g/cm^3$. The breakdown field decreased from 5919 to 1465 V/cm because of the increase in the average grain size. Zinc oxide ceramics sintered at $875^{\circ}C$ showed the highest nonlinear coefficient (43.6) and the highest potential barrier height (0.96 eV). Zinc oxide ceramics sintered at $850^{\circ}C$ showed the highest stability: the variation rate of the breakdown field was -2.0% and the variation rate of the nonlinear coefficient was -23.3%, after application of the specified stress (applied voltage/temperature/time).

Low Temperature Sintering of PNN-PZT Ceramics and Its Electrical Properties (PNN-PZT 세라믹스의 저온 소결 및 전기적 특성 평가)

  • Lee, Myung-Woo;Kim, Sung-Jin;Yoon, Man-Soon;Ryu, Sung-Lim;Kweon, Soon-Yong
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.21 no.12
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    • pp.1077-1082
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    • 2008
  • To fabricate a multi-layered piezoelectrics/electrodes structure, the piezoelectrics should be sintered at the temperature lower than $950^{\circ}C$ to use the silver electrode, which is cheaper than the electrodes containing noble metals such as Pd and Pt. Therefore, in this study, we modified the composition of $Pb(Zr,Ti)O_3$-based material as $(Pb_{0.98}Cd_{0.02})(Ni_{1/3}Nb_{2/3})_{0.25}Zr_{0.35}Ti_{0.4}O_3$ to lower the sintering temperature and to improve the piezoelectric properties. Small amount of $MnCO_3$, $SiO_2$, and $Pb_3O_4$ were also added to lower the sintering temperature of the ceramic. The prepared raw powders were mixed by using a ball mill for 24 hours. And then the mixed powders were calcinated for 2 hours at $800^{\circ}C$. The calcinated powders were again crushed with the ball mill for 72 hours. The final powders were pressed for making the shape of ${\emptyset}15\;mm$ disk. The disk-type samples were sintered at temperature range of $850{\sim}950^{\circ}C$. The crystal phases of the sintered specimens were perovskite structure without secondary phases. All of the measured electrical properties such as electromechanical coupling coefficients ($k_p$), mechanical quality factors ($Q_m$), and piezoelectric charge constants ($d_{33}$) were decreased with decreasing the sintering temperatures. The electrical properties measured at the sample sintered at $950^{\circ}C$ were 54% of $k_p$, 503 of $Q_m$, and 390 pC/N of $d_{33}$, respectively. These properties were considered to be fairly good for the application of multi-layered piezoelectric generators or actuators.

Characterization for Electrical Properties of Sintered 20mol% Gd-doped CeO$_2$ Electrolyte (20mol% Gd-doped 소결체 CeO$_2$ 전해질의 전기적 특성분석)

  • 김선재;국일현
    • Journal of the Korean Ceramic Society
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    • v.35 no.1
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    • pp.97-105
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    • 1998
  • 20mol% Gd-doped CeO2 ultrafine powders as a promising electrolyte for the low temperature solid ox-ide fuel cells were synthesized with particle sizes of 15-20 nm using glycine nitrate process(GNP) fol-lowed by sintering their pellets at 150$0^{\circ}C$ for various times in air and then the electrical properties of the sintered pellets were investigated. The sintering behaviors and electrical properties for the sintered 20 sintered mol% Gd-doped CeO2 pellets were analyzed using dilatometer and SEM and AC two-terminal impedance technique respectively. As the heating temperature increased the synthesized powder had the sintering behaviors to show the start of the significant shrink at temperature of about $700^{\circ}C$ and to show the end of the shrink at the temperature of about 147$0^{\circ}C$. When the pellets were sintered with the vaious times at 150$0^{\circ}C$ the temperatuer which the shrink had been already completed the grain sizes in the sintered 20 mol% Gd-doped GeO2 pellets increased with the increase of the sintering time but their electrical resis-tivities showed the minimum value at the sintering time of 10h. It is due that the pellet sintered for 10h had the minimum activation energy fior the electtrical conduction. Thus it is thought that the decrease of the activation energy with the increase of the sintering time to 10h is induced by the enhanced mi-crostructure like the decrease of pore amount and the grain growth and its increase with the sintering times more than 10h is induced by the increase of the amounts of the impurities such as Mg. Al and Si from the sintering atmosphere.

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Microstructural and Piezoelectric Properties of Low Temperature Sintering PMN-PZT Ceramics with the Variations of Sintering Times (저온소결 PMN-PZT 압전세라믹의 소성시간에 따른 미세구조 및 압전특성)

  • Yoo, Ju-Hyun;Lee, Chang-Bae;Lee, Sang-Ho;Paik, Dong-Soo;Jeong, Yeong-Ho;Im, In-Ho
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.18 no.3
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    • pp.237-242
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    • 2005
  • In this paper, in order to develop the low temperature sintering ceramics for multilayer piezoelectric transformer, PMN-PZT ceramics were manufactured with the variations of sintering times, and their microstructural, piezoelectric and dielectric properties were investigated. Li$_2$CO$_3$ and Bi$_2$O$_3$ were used as sintering aids and the specimens were sintered during 30, 60, 90, 120, 150, and 180 minutes, respectively. At the specimen sintered during 90 minute, mechanical quality factor(Qm), electro-mechanical coupling factor(kp) and dielectric constant were showed the optimum values of 2,356, 0.504 and 1,266, respectively.

Microwave Dielectric Properties of Low-temperature Sintered $Mg_4Nb_2O_9$ Ceramics (저온소결 $Mg_4Nb_2O_9$ 세라믹스의 마이크로파 유전특성)

  • Lee, Ji-Hun;Bang, Jae-Cheol
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2004.11a
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    • pp.439-442
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    • 2004
  • The effects of sintering additives on the low-temperature sintering and microwave dielectric properties of $Mg_4Nb_2O_9$ dielectric ceramics were studied. When $3{\sim}20wt%$ of $0.242Bi_2O_3-0.758V_2O_5$ was added, the sintering temperature decreased from $1100{\sim}1300^{\circ}C$ to $950^{\circ}C$ and high density was obtained. When $Mg_4Nb_2O_9$ was sintered at $950^{\circ}C$ with 10wt% of sintering additive, the microwave dielectric properties of $Q{\times}f_0\;=\;80.035GHz,\;\epsilon_r\;=\;13.3\;and\;\tau_f\;=\;-12.9\;ppm/^{\circ}C$ were obtained.

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