• 제목, 요약, 키워드: Microwave microscopy

검색결과 110건 처리시간 0.044초

Microwave Dielectric Properties of Bi2O3-TiO2 Composite Ceramics

  • Axelsson, Anna-karin;Sebastian, Maladil;McN Alford, Neil
    • 한국세라믹학회지
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    • v.40 no.4
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    • pp.340-345
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    • 2003
  • B $i_2$ $O_3$-Ti $O_2$ composite dielectric ceramics have been prepared by a conventional solid state ceramic route. The composite ceramics were prepared with starting materials of different origin and the microwave dielectric properties were investigated. The sintered ceramics were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray microanalysis, Raman and microwave methods. Structural and microstructural analyses identified two separate phases: Ti $O_2$(rutile) and B $i_2$ $Ti_4$0$_{11}$. The separate grains of titania and bismuth titanate were distributed uniformly in the ceramic matrix. The composition 0.88Ti $O_2$-0.12B $i_2$ $Ti_4$ $O_{11}$ was found to have a Q$\times$f of 9300 GHz (measured at a frequency of 3.9 GHz), a temperature coefficient of frequency, $\tau$$_{cf}$ near zero and a high relative permittivity, $\varepsilon$r of 83. The microwave dielectric properties were measured down to 20$^{\circ}$K K. The quality factor increased on cooling the ceramic samples.les.

Heating Behavior of Silicon Carbide Fiber Mat under Microwave

  • Khishigbayar, Khos-Erdene;Seo, Jung-Min;Cho, Kwang-Youn
    • 한국세라믹학회지
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    • v.53 no.6
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    • pp.707-711
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    • 2016
  • A small diameter of SiC fiber mat can produce much higher heat under microwave irradiation than the other types of SiC materials. Fabrication of high strength SiC fiber consists of iodine vapor curing on polycarbosilane precursor and heat treatment process. The curing stage of polycarbosilane fiber was maintained at $150-200^{\circ}C$ in a vacuum condition under the iodine vapor to fabricate a high thermal radiation SiC fiber. The structure and morphology of the fibers were characterized by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TG) and scanning electron microscopy (SEM). In this study, the thermal properties of SiC fiber mats under microwave have been analyzed with an IR thermal camera and its image analyzer. The prepared SiC fiber mats radiated high temperature with extremely high heating rate up to $1100^{\circ}C$ in 30 seconds. The fabricated SiC fiber mats were not oxidized after the heat radiation process under the microwave irradiation.

마이크로파 공정을 이용한 나노복합체의 제조 (Preparation of Nanocomposite by Microwave Processing)

  • 김태훈;손세모;박지환;서금석;박성수
    • 한국인쇄학회지
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    • v.22 no.2
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    • pp.111-122
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    • 2004
  • The purpose of this study was to investigate the possibility of application of microwave energy for the fabrication of polymer/clay nanocomposite. APES/Clay nanocomposites were prepared at $130^{\circ}C$ for 30min with various amount of MMT or OMMT used the melt-intercalation method applied the classical and microwave heating source. APES/Clay samples were characterized by the means of X-ray diffractometry (XRD), transmitted electron microscopy (TEM) differential scanning calorimetry (DSC), and rheometric dynamic analysis (RDA). It was found that intercalated or exfoliated state of the samples could be controlled by the clay type, clay content, and heating type.

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$CaZr(BO_3)_2$ 세라믹스의 저온 소결 및 마이크로웨이브 유전 특성 (Low Temperature Sintered $CaZr(BO_3)_2$ Microwave Dielectric Ceramics for LTCC Application)

  • 남명화;김효태;김종희;남산
    • 한국전기전자재료학회:학술대회논문집
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    • pp.259-259
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    • 2007
  • The low temperature sintering of dolomite type borates, $CaZr(BO_3)_2$[CZB] ceramics and their microwave dielectric properties were investigated The sintering temperature of CZB ceramics could be reduced from $1150^{\circ}C$ to $925^{\circ}C$ by the addition of sintering additive. $CaZrO_3$, $ZrO_2$ and $CaB_2O_4$ second phases were found in the CZB ceramics. The syntheses, sintering properties, microstructures, and dielectricnproperties of dolomite-type borates were examined by XRD, thermal analysis, electron microscopy, network analyzer, and the results are discussed intensively. The compatibility with silver electrode was also explored.

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Theoretical and Experimental Investigation on the Probe Design of a Ridge-loaded Slot Type for Near-Field Scanning Microwave Microscope

  • Son, Hyeok-Woo;Kim, Byung-Mun;Hong, Jae-Pyo;Cho, Young-Ki
    • Journal of Electrical Engineering and Technology
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    • v.10 no.5
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    • pp.2120-2125
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    • 2015
  • In this paper, a rectangular waveguide probe with a ridge-loaded straight slot (RLSS) is presented for a near-field scanning microwave microscope (NSMM). The RLSS is located laterally at the end wall of the cavity and is loaded on double ridges in a narrow straight slot to improve the spatial resolution compared with a straight slot. The probe consists of a rectangular cavity with an RLSS and a feed section of a WR-90 rectangular waveguide. When the proposed NSMM is located at distance of 0.1mm in front of a substrate without patches or strips, the simulated full width at half maximum (FWHM) of the probe improve by approximately 31.5 % compared with that of a straight slot without ridges. One dimensional scanning of the E-plane on a sample under test was conducted, and the reflection coefficient of the near-field scanning probe is presented.

Synthesis of Carbon Nanowalls by Microwave PECVD for Battery Electrode

  • Kim, Sung Yun;Shin, Seung Kwon;Kim, Hyungchul;Jung, Yeun-Ho;Kang, Hyunil;Choi, Won Seok;Kweon, Gi Back
    • Transactions on Electrical and Electronic Materials
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    • v.16 no.4
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    • pp.198-200
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    • 2015
  • The microwave plasma enhanced chemical vapor deposition (PECVD) system was used to grow a carbon nanowall (CNW) on a silicon (Si) substrate with hydrogen (H2) and methane (CH4) gases. To find the growth mechanism of CNW, we increased the growth time of CNW from 5 to 30 min. The vertical and surficial conditions of the grown CNWs according to growth time were characterized by field emission scanning electron microscopy (FE-SEM). Energy dispersive spectroscopy (EDS) measurements showed that the CNWs consisted solely of carbon.

Easy Preparation of Nanosilver-Decorated Graphene Using Silver Carbamate by Microwave Irradiation and Their Properties

  • Yun, Sang-Woo;Cha, Jae-Ryung;Gong, Myoung-Seon
    • Bulletin of the Korean Chemical Society
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    • v.35 no.8
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    • pp.2251-2256
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    • 2014
  • We have successfully decorated reduced graphene oxide (RGO) with silver nanoparticles (AgNPs) by microwaving silver alkylcarbamate for 13 seconds using 1-amino-4-methylpiperazine. Uniform AgNPs (20-40 nm) were effectively prepared, and 1-amino-4-methylpiperazine acted as a reaction medium, reducing agent, and stabilizer. Particle size and morphology were correlated with the silver alkylcarbamate concentration and microwave time. The graphene/AgNPs composites were characterized by Raman, X-ray diffraction, and scanning electron microscopy to confirm that the AgNPs were uniformly decorated onto the graphene. Measurements of the transparent conductive property at room temperature indicated that these graphene/AgNPs nanosheets with 55.45% transmittance were electrically continuous with a sheet resistance of approximately $43{\Omega}/{\Box}$.

SHS 마이크로파에 의한 (Ti.Si)C 복합체의 합성 및 소결특성에 관한 연구 (Study on Synthesis and Characterization of (Ti.Si)C Composite by SHS Microwave)

  • 이형복;권상호;이재원;안주삼
    • 한국세라믹학회지
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    • v.32 no.9
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    • pp.1009-1018
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    • 1995
  • (Ti.Si)C composite powders were synthesized by SHS method using microwave energy. Compositional and structural characterization of the powder were carried out by using scanning electron microscopy and X-ray diffraction. The average particle size of the synthesized (Ti.Si)C composite powders was smaller than that of the starting materials. From the results of the temperature profile, combustion temperature and velocity were decreased with increasing Si molar ratio. With increasing C molar ratio combustion temperature and velocity did not change. (Ti.Si)C composite was sintered at 185$0^{\circ}C$ for 60 min by using hot-pressing with 30 MPa. The best properties were obtained from the sintered specimen whose composition was 1 : 1 : 1.9 molar ratio of Ti : Si : C. The sintering density, flexural strength and vickers hardness of the sintered body were 4.71 g/㎤, 423 MPa and 21 GPa, respectively.

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Microwave-Assisted Heating of Electrospun SiC Fiber Mats

  • Khishigbayar, Khos-Erdene;Joo, Young Jun;Cho, Kwang Youn
    • 한국세라믹학회지
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    • v.54 no.6
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    • pp.499-505
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    • 2017
  • Flexible silicon carbide fibrous mats were fabricated by a combination of electrospinning and a polymer-derived ceramics route. Polycarbosilane was used as a solute with various solvent mixtures, such as toluene and dimethylformamide. The electrospun PCS fibrous mats were cured under a halogen vapor atmosphere and heat treated at $1300^{\circ}C$. The structure, fiber morphology, thermal behavior, and crystallization of the fabricated SiC fibrous mats were analyzed via scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermal imaging. The prepared SiC fibrous mats were composed of randomly distributed fibers approximately $3{\mu}m$ in diameter. The heat radiation of the SiC fiber mats reached $1600^{\circ}C$ under microwave radiation at a frequency of 2.45 GHz.

절연물질이 코팅된 활성탄의 벤젠 흡착특성 및 마이크로파에 의한 탈착에 관한 연구 (A Study on Adsorption Characteristics of Benzene over Activated Carbons Coated with Insulating Materials and Desorption by Microwave Irradiation)

  • 김기중;안호근
    • 공업화학
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    • v.19 no.4
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    • pp.445-451
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    • 2008
  • 마이크로파를 이용하여 휘발성유기화합물(VOCs; Volatile Organic Compounds)로 오염된 활성탄을 재생하기 위하여, 절연물질로서 활석(Talc)과 Ni-Zn ferrite를 각각 활성탄에 코팅하여 벤젠의 흡착 및 탈착 특성을 조사하였다. 절연물질이 코팅된 활성탄의 물리적 특성 및 표면상태는 질소가스 흡착장치와 주사전자현미경(SEM)을 이용하여 각각 확인하였다. 비표면적과 벤젠에 대한 흡착량은 비례관계를 보였고, 활성탄에 활석이나 Ni-Zn ferrite를 코팅하면 마이크로파에 의한 불꽃방전을 억제할 수 있었다. 활성탄에 절연물질을 코팅하기 위해 사용한 바인더는 PS (potassium silicate)가 벤젠에 대한 흡착성능이 가장 우수한 것으로 나타났다. 마이크로파 출력에 따른 탈착량은 출력에 비례하는 경향을 보였고, 연속되는 흡착과 탈착과정이 5회 반복되더라도 재현성이 충분히 나타났다. 결과적으로 VOCs로 오염된 폐활성탄의 재생방법으로서, PS를 바인더로 사용하여 활석이나 Ni-Zn ferrite를 활성탄에 코팅하여 마이크로파로 탈착시키면 효과적임을 알 수 있었다.