• Title/Summary/Keyword: Ceramic composite

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A sintering Behavior of Glass/Ceramic Composite used as substrate in High Frequency Range (고주파대역에서 기판으로 쓰이는 Glass/Ceramics Composite의 소결거동)

  • 이찬주;김형준;최성철
    • Journal of the Korean Ceramic Society
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    • v.37 no.4
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    • pp.302-307
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    • 2000
  • The objective of this study was to investigate the sintering behavior, crystallization characteristic of glass-ceramic and optimal sintering condition on the glass/ceramic composite for fabricating substrate of LTCC. Glass/ceramic composite was made from alumina powder and glass frit, which was composed of SiO2-TiO2-RO-PbO/(R: Ba, Sr, Ca), and was sintered for 0, 30, 60minutes in the temperature range from 700$^{\circ}C$ to 1000$^{\circ}C$. Properties of frit and glass/ceramic compsoite were analyzed by DTA, XRD, SEM and Network Analyzer and so on. Main sintering mechanism was densification occurred above 730$^{\circ}C$ by viscous flow and crystallization starting about 780$^{\circ}C$ affected sintering also. So viscous flow was affected by sintering temperature, duration time, and creation of crystallization phase etc. From this study, it was possible to fabricate glass/ceramic composite by changing sintering temperature and duration time.

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Biomimetic Preparation of Boron Nitride /PMMA Composite (생체모방기술을 이용한 Boron Nitride /PMMA 복합체 제조)

  • Nam, Kyung Mok;Lee, Yoon Joo;Kim, Bo Yeon;Kwon, Woo Teck;Kim, Soo Ryong;Shin, Dong Geun;Kim, Young Hee
    • Journal of the Korean Ceramic Society
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    • v.51 no.2
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    • pp.103-106
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    • 2014
  • Nacre is an organic-inorganic composite material; it is composed of $CaCO_3$ platelet and protein. The microstructure of nacre is a matrix that is similar to bricks and mortar. Technology inspired by nature is called biomimetic technology. In this study, to make high thermal conducting ceramic composite materials using biomimetic technology, a porous green body was prepared with BN platelets. PMMA was infiltrated into the porous green body to make a composite. The microstructure of the composite was observed with FESEM, and the thermal properties were measured. The thermal conductivity of the prepared organic-inorganic composite was 4.19 $W/m{\cdot}K$.

Bio-Inspired Synthesis of a Silicate/PMMA Composite

  • Nam, Kyung Mok;Lee, Yoon Joo;Kwon, Woo Teck;Kim, Soo Ryong;Shin, Dong-Geun;Lim, Hyung Mi;Kim, Hyungsun;Kim, Younghee
    • Journal of the Korean Ceramic Society
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    • v.51 no.1
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    • pp.7-10
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    • 2014
  • Abalone shell is composed of 95 wt% $CaCO_3$ platelets and 5 wt% of a protein-rich organic matrix which acts as an adhesive layer, connecting aragonite tablets, thus maintaining the structural integrity of the composite. By mimicking abalone shell, we prepared a silicate plate/polymer nanocomposite by infiltrating PMMA between silicate layers and warm-pressing them at $200^{\circ}C$ for 1 h under 15 tons to make organic-inorganic composite materials. To examine the organic-inorganic composite materials after the warm-pressing procedure, the composite sample was analyzed with FE-SEM and TG. The bending strengths and densities of the composites prepared by a silicate plate and PMMA after the warm-pressing process were ~140 MPa and 1.5, respectively.

Catalytic Effects of Barium Carbonate on the Anodic Performance of Solid Oxide Fuel Cells

  • Yoon, Sung-Eun;Ahn, Jae-Yeong;Park, Jong-Sung
    • Journal of the Korean Ceramic Society
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    • v.52 no.5
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    • pp.350-355
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    • 2015
  • To develop ceramic composite anodes of solid oxide fuel cells without metal catalysts, a small amount of barium carbonate was added to an $(La_{0.8}Sr_{0.2})(Cr_{0.5}Mn_{0.5})O_3(LSCM)$ - YSZ ceramic composite anode and its catalytic effects on the electrode performance were investigated. A barium precursor solution with citric acid was used to synthesize the barium carbonate during ignition, while a barium precursor solution without citric acid was used to create hydrated barium hydroxide. The addition of barium carbonate to the ceramic composite anode caused stable fuel cell performance at 1073 K; this performance was higher than that of a fuel cell with $CeO_2$ catalyst; however, the addition of hydrated barium hydroxide to the ceramic composite anode caused poor stability of the fuel cell performance.

Dynamic behavior of cracked ceramic reinforced aluminum composite beam

  • Selmi, Abdellatif
    • Smart Structures and Systems
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    • v.29 no.3
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    • pp.387-393
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    • 2022
  • This paper presents the vibration analysis of cracked ceramic-reinforced aluminum composite beams by using a method based on changes in modal strain energy. The crack is considered to be straight. The effective properties of composite materials of the beams are estimated through Mori-Tanaka micromechanical model. Comparison study and numerical simulations with various parameters; ceramic volume fraction, reinforcement aspect ratio, ratio of the reinforcement Young's modulus to the matrix Young's modulus and ratio of the reinforcement density to the matrix density are taken into investigation. Results demonstrate the pronounced effects of these parameters on intact and cracked ceramic aluminum beams.

Dielectric and Piezoelectric of Ceramic-Polymer Composite with Ceramic Particle Size (세라믹 분말 크기가 압전 세라믹-폴리머 복합체의 유전 및 압전 특성에 미치는 영향)

  • 이형규;김호기
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1989.06a
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    • pp.63-65
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    • 1989
  • Piezoelectric BaTiO$_3$-polymer composite were investigated for dielectric and piezoelectric properties with the barium titanate active particle size. Under the condition of the same density and ceramic volume ratio of composite, the dielectric and piezoelectric constant of composite are increasing as the ceramic particle size in composite are increasing. The surface layer model was quoted to explain these phenomena in our system and experimentally confirmed. The connectivity parameter of modified cube model of composite was calculated from the dielectric constant variation as their particle size. The connectivity parameter X and Y were 77.8% and 98.9% respectively. It means that the barium titanate particle distribution in composite nearly approach to the parallel mode. It was experimentally confirmed that the surface layer has low dielectric and nonferroelectric properties. Dielectric constant and thickness of surface layer were calculated from the equivalent circuit of composite.

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Health Monitoring of a Composite Actuator with a PZT Ceramic during Electromechanical Fatigue Loading

  • Woo, Sung-Choong;Goo, Nam-Seo
    • Journal of the Korean Society for Nondestructive Testing
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    • v.27 no.6
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    • pp.541-549
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    • 2007
  • This work describes an investigation into the feasibility of using an acoustic emission (AE) technique to evaluate the integrity of a composite actuator with a PZT ceramic under electromechanical cyclic loading. AE characteristics have been analyzed in terms of the behavior of the AE count rate and signal waveform in association with the performance degradation of the composite actuator during the cyclic tests. The results showed that the fatigue cracking of the composite actuator with a PZT ceramic occurred only in the PZT ceramic layer, and that the performance degradation caused by the fatigue damage varied immensely depending on the existence of a protecting composite bottom layer. We confirmed the correlations between the fatigue damage mechanisms and AE signal types for the actuators that exhibited multiple modes of fatigue damage; transgranular micro damage, intergranular fatigue cracking, and breakdown by a short circuiting were related to a burst type signal showing a shortly rising and slowly decaying waveform with a comparably low voltage, a continuous type signal showing a gradual rising and slowly decaying waveform with a very high voltage and a burst and continuous type signal with a high voltage, respectively. Results from the present work showed that the evolution of fatigue damage in the composite actuator with a PZT ceramic can be nondestructively identified via in situ AE monitoring and microscopic observations.

고충전 polymer/ceramic composite에서 유전 특성의 mixing rule

  • Lee, Ji-Ae;Sin, Hyo-Sun;Hong, Yeon-U;Yeo, Dong-Hun;Kim, Jong-Hui;Yun, Ho-Gyu
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2008.06a
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    • pp.309-309
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    • 2008
  • 전자 산업의 발달로 인해 전자기기에 소형화, 경량화 및 다기능화가 요구되면서 고밀도화, 고집적화가 필요하게 되었다. 이와 같은 부품의 고집적화 기술로 최근 제시되고 있는 방법 중 하나는 ceramic powder로 구성된 유전층에 polymer를 infiltration시키고 cure 과정을 거쳐 소결공정 없이 유전층을 완성하는 것이다. 그리고 이 유전층을 layer 단위로 build up하는 방법을 이용하여 반복적으로 형성하는 기술이 연구되고 있다. 그러나 고충전된 polymer/ceramic composite에서 유전 특성은 기존에 알려진 저충전 구조에서의 mixing 이론을 따를 것인지에 대한 실증적인 연구는 이루어지지 않았다. 본 연구에서는 ceramic powder $Al_2O_3$를 이용하여 polymer의 함량을 최소화하여 paste 를 제조하고, 스크린 프린팅 방법으로 인쇄하여 ceramic layer를 제작하였다. 그리고 이 위에 polymer infiltration 과정을 동하여 고충전 ceramic/polymer composite layer를 제작하였다. 또한, $Al_2O_3$를 filter로 사용한 저충전 polymer/ceramic composite에서의 mixing rule과 비교하여 복합체의 유전 특성을 설명하였다.

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Preparation of Al2O3 Platelet/PMMA Composite and Its Mechanical/Therml Characterization (판상 Al2O3/PMMA 복합체 제조 및 기계적/열적 특성분석)

  • Nam, Kyung Mok;Lee, Yoon Joo;Kwon, Woo Teck;Kim, Soo Ryong;Lim, Hyung Mi;Kim, Hyungsun;Kim, Younghee
    • Journal of the Korean Ceramic Society
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    • v.49 no.5
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    • pp.438-441
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    • 2012
  • Abalone shell is a high strength and light weighted ceramic composite material, which is composed of $CaCO_3$ platelet and protein. Microstructure of abalone shell has a matrix structure that is similar to the bricks and mortar. The technology inspired from nature which consumes low energy at low temperature is called bioinspired technology. In this study, to make high strength and light weighted ceramic composite materials using bioinspired technology, porous green body was prepared with $Al_2O_3$ platelet. PMMA was infiltrated into the porous green body, then warm pressed to eliminate pores present in the composite. The microstructure of the composite was observed with FESEM, and the mechanical/thermal properties were measured.