• 제목/요약/키워드: ultrasonic synthesis

검색결과 132건 처리시간 0.044초

초음파 밀링 공정을 이용한 텅스텐 중합금 나노복합분말의 제조 (Synthesis of Tungsten Heavy alloy Nanocomposite Powder by Ultrasonic-milling Process)

  • 이승철;이창우;정성수;차범하;이재성
    • 한국분말재료학회지
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    • 제14권2호
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    • pp.101-107
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    • 2007
  • Ultrasonic-milling of metal oxide nanopowders for the preparation of tungsten heavy alloys was investigated. Milling time was selected as a major process variable. XRD results of metal oxide nanopowders ultrasonic-milled for 50 h and 100 h showed that agglomerate size reduced with increasing milling time and there was no evidence of contamination or change of composition by impurities. It was found that nanocomposite powders reduced at $800^{\circ}C$ in a hydrogen atmosphere showed a chemical composition of 93.1W-4.9Ni-2.0Fe from EDS analysis. Hardness of sintered part using 50 h and 100 h powder samples was 399 Hv and 463 Hv, respectively, which is higher than the that of commercial products (330-340 Hv).

초음파 분무 열분해법에 의한 산화물 환원 공정의 구형 Bi2Te3 분말 합성 (Spherical Bi2Te3 Powder Synthesized by Oxide-Reduction Process via Ultrasonic Spray Pyrolysis)

  • 송철한;장대환;진연호;공만식
    • 한국표면공학회지
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    • 제50권2호
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    • pp.114-118
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    • 2017
  • Bismuth telluride ($Bi_2Te_3$) and its alloys are well-known thermoelectric materials for ambient temperature applications. In this study, the dissolved Bi-Te precursor solution was used to synthesis metallic $Bi_2Te_3$ powder via ultrasonic spray pyrolysis and reduction process. The droplets of the Bi-Te precursor solution were decomposed to Bi-Te oxide powders by ultrasonic spray pyrolysis. The spherical $Bi_2Te_3$ powders were synthesized by reduction reaction in atmosphere of hydrogen gas at the temperature above $375^{\circ}C$ for 6h. The reduced $Bi_2Te_3$ powders have a mean particle size of $1.5{\mu}m$. The crystal structure of the powder was evaluated by X-Ray diffraction(XRD), and the microstructure with size and shape powders was observed by fieldemission scanning electron microscope(FE-SEM) and transmission electron microscope(TEM).

초음파 분무에 의한 (Y,Gd)$BO_3:Eu^{3+}$ 형광체의 제조와 이의 발광 특성 (The Synthesis of (Y,Gd)$BO_3:Eu^{3+}$Phosphor by Ultrasonic Spray and Their Photoluminance Properties)

  • 김대수;김성우;이임렬
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 1999년도 추계학술대회 논문집
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    • pp.107-110
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    • 1999
  • The ultrasonic spray method was employed to make (Y,Gd)BO$_3$:Eu Phosphor, and its optical properties under 147nm VUV and 254 nm UV excitations were characterized and then compared with that produced by the solid-state reaction. The mixed solution of acetate hydrates of Y, Gd, Eu and boric acid diluted in water or methanol was used as the precursor fur the spray. It was found that (Y,Gd)BO$_3$:Eu phosphor made by this ultrasonic spray had a spherical shape and fine particle size of 1${\mu}{\textrm}{m}$. The crystalline structure for the as-sprayed phosphor was amorphous, but it converted into the same polycrystalline phase of solid state reaction after post heat treatment at 110$0^{\circ}C$ for 2hr. The emitting intensity under VUV and UV excitations for the spray-formed (Y,Gd)BO$_3$:Eu phosphor, however, was inferior to the later one. The excitation spectra were also studied and compared under VUV and UV excitations to explain the change of emitting intensity with Gd substitution in (Y$_{1-x}$ Gd$_{x}$)BO$_3$:Eu Phosphors made by spray and solid state reaction.on.

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Synthesis of Zinc Oxide Nanoparticle-(C60) Fullerene Nanowhisker Composite for Catalytic Degradation of Methyl Orange under Ultraviolet and Ultrasonic Irradiation

  • Ko, Jeong Won;Son, Yeon-A;Ko, Weon Bae
    • Elastomers and Composites
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    • 제55권4호
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    • pp.321-328
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    • 2020
  • Zinc nitrate hexahydrate (Zn(NO3)2·6H2O) and sodium hydroxide (NaOH) were dissolved in distilled water and stirred for 30 min. The resulting solution was sonicated by an ultrasonic wave for 45 min. This solution was washed with distilled water and ethanol after centrifugation; next, it was placed in an electric furnace at 200℃ for 1 h under the flow of Ar gas to obtain zinc oxide nanoparticle. A zinc oxide nanoparticle-(C60) fullerene nanowhisker composite was synthesized using the zinc oxide nanoparticle solution, C60-saturated toluene, and isopropyl alcohol via the liquid-liquid interfacial precipitation method. The zinc oxide nanoparticle and zinc oxide nanoparticle-(C60) fullerene nanowhisker composite were characterized using X-ray diffraction, scanning electron microscopy, and Raman spectroscopy, and they were used for the catalytic degradation of methyl orange (MO) under ultraviolet (at 254 and 365 nm) and ultrasonic irradiation. In addition, the catalytic degradation of MO over the zinc oxide nanoparticle and zinc oxide nanoparticle-(C60) fullerene nanowhisker composite was evaluated using ultraviolet-visible spectroscopy.

초음파 트랜스듀서용 PZT-고분자 3-3형 복합압전체의 유전 및 압전특성 (Dielectric and piezoelectric properties of PZT-polymer 3-3 type composite for ultrasonic transducer applications)

  • 박정학;이수호;최헌일;사공건;배진호
    • E2M - 전기 전자와 첨단 소재
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    • 제9권2호
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    • pp.146-151
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    • 1996
  • PZT powders were prepared by the molten salt synthesis method. The porous PZT ceramics were made from a mixture of PZT and polyvinylalcohol(PVA) by BURPS(Bumout Plastic Sphere) technique. The 3-3 type composites were fabricated by impregnating an sintered porous PZT ceramics with various polymer matrices. The relative permittivity of 3-3 type composite specimens was shown 860-1,100 smaller than that of solid PZT ceramics(2,100), and the dissipation factors of composite specimens were about 0.02 to 0.03. The piezoelectric coefficient d$_{33}$ of composite specimens(285-328*10$^{12}$ C/N) was comparable with that of single phase PZT specimens(364*10$^{-12}$ C/N). The thickness mode coupling factor k$_{t}$(O.5-0.6) of composite specimens was comparable with that of single phase PZT specimens(k$_{t}$-0.7), and the mechanical quality factor of composite specimens was smaller than 10, and thus these 3-3 type composite specimens would be believed as a good candidates for broad band transducer applications.ons.

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