• 제목/요약/키워드: advanced materials

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이중 주파수를 이용한 펄스 유도 결합 플라즈마 특성 연구

  • 김기현;김태형;이승민;이철희;김경남;배정운;염근영
    • 한국표면공학회:학술대회논문집
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    • 한국표면공학회 2015년도 춘계학술대회 논문집
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    • pp.84-84
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    • 2015
  • 플라즈마를 이용한 반도체 미세 공정에서 플라즈마 밀도, 균일성 등과 같은 플라즈마 특성을 조절하는 것은 차세대 공정 장비 개발에 있어 매우 중요한 요소이다. 본 연구에서는 이러한 플라즈마 특성을 효율적으로 제어하기 위해 서로 다른 주파수를 사용하는 2개의 안테나에 pulse 신호를 적용하여 각 안테나에 인가되는 펄스 신호에 따른 플라즈마의 특성을 알아보았다.

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Improvement of Field Emission Characteristics of Carbon Nanotubes by Oxidative Electrical Trimming

  • Jeon, Ji-Hyeon;Lee, Han-Sung;Kim, Jin-Hee;Kim, Young-Rea;Jeon, Hong-Jun;Goak, Jung-Chun;Lee, Nae-Sung
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2007년도 추계학술대회 논문집
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    • pp.384-385
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    • 2007
  • 탄소나노튜브의 전계방출 특성은 그 길이에 많은 영향을 받으며 길이가 균질 할수록 전계방출에 참여하는 탄소나노튜브의 수가 증가하여 전자방출의 균일도가 향상되고 수명도 증가할 것으로 기대되고 있다. 이 논문에서는 탄소나노튜브의 길이를 인위적으로 제어하여 균질하게 하기 위해 오존을 이용하여 길이가 긴 탄소나노튜브만 선택적으로 제거하는 방법을 사용하였다. 오존에 의해 처리한 시편은 전에 비해 높은 균일도를 나타내고 수명도 약 4배가량 크게 향상되었다.

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GaMnAs의 Be 병행 도핑에 의한 자기 수송 특성 연구 (Magnetotransport of Be-doped GaMnAs)

  • 임완순;윤대식;우부성;고존서;김도진;임영언;김효진;김창수;김종오
    • 한국재료학회지
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    • 제15권1호
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    • pp.73-77
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    • 2005
  • Motivated by the enhanced magnetic properties of Mg-codoped GaMnN ferromagnetic semiconductors, Be-codoped GaMnAs films were grown via molecular beam epitaxy with varying Mn flux at a fixed Be flux. The structural, electrical, and magnetic properties were investigated. GaAs:(Mn,Be) films showed metallic behavior while GaAs:Mn films showed semiconducting behavior as determined by the temperature dependent resistivity measurements. The Hall-effect measurements with varying magnetic field showed clear anomalous Hall effect up to room temperature proving ferromagnetism and magnetotransport in the GaAs:(Mn,Be) films. Planar Hall resistance measurement also confirmed the properties. The dramatic enhancement of the Curie temperature in GaMnAs system was attributed to Be codoping in the GaMnAs films as well as MnAs precipitation.

스파크플라즈마 소결에 의한 Ti-Nb-Zr-Mo-CPP 생체복합재의 기계적 성질 및 생체적합성 (Mechanical Properties and Biocompatibility of Ti-Nb-Zr-Mo-CPP Biomaterial Fabricated by Spark Plasma Sintering)

  • 우기도;김상미;김동건;김대영;강동수
    • 한국재료학회지
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    • 제23권2호
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    • pp.135-142
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    • 2013
  • The Ti-6Al-4V extra low interstitial (ELI) alloy has been widely used as an orthopedic implant material because of its excellent mechanical properties and biocompatibility. However, it still has many problems, including a high elastic modulus and toxicity of the Al and V elements. Therefore, non-toxic biomaterials with a low elastic modulus need to be developed. A high energy mechanical milling (HEMM) process is introduced to improve the effect of sintering. Rapid sintering of spark plasma sintering (SPS) under pressure was used to make an ultra fine grain of Ti-25 wt.%Nb-7 wt.%Zr-10 wt.%Mo-(10 wt.%CPP) composites with bio-attractive elements for increasing strength. These composites were fabricated by SPS at $1000^{\circ}C$ at 60 MPa using HEMM powders. During the sintering process, $CaTiO_3$, TixOy, and CaO were formed because of the reaction between Ti and CPP. The effects of CPP content on the physical and mechanical properties of the sintered Ti-Nb-Zr-Mo-CPP composites were investigated. The biocompatibility and corrosion resistance of the Ti-Nb-Zr-Mo alloys were improved by the addition of CPP.

Investigation on Microstructure and Flowability of Gas Atomized Heat-resistant KHR45A Alloy Powders for Additive Manufacturing

  • Geonwoo Baek;Mohsen Saboktakin Rizi;Yeeun Lee;SungJae Jo;Joo-Hyun Choi;Soon-Jik Hong
    • 한국분말재료학회지
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    • 제30권1호
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    • pp.13-21
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    • 2023
  • In additive manufacturing, the flowability of feedstock particles determines the quality of the parts that are affected by different parameters, including the chemistry and morphology of the powders and particle size distribution. In this study, the microstructures and flowabilities of gas-atomized heat-resistant alloys for additive manufacturing applications are investigated. A KHR45A alloy powder with a composition of Fe-30Cr-40Mn-1.8Nb (wt.%) is fabricated using gas atomization process. The microstructure and effect of powder chemistry and morphology on the flow behavior are investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and revolution powder analysis. The results reveal the formation of spherical particles composed of single-phase FCC dendritic structures after gas atomization. SEM observations show variations in the microstructures of the powder particles with different size distributions. Elemental distribution maps, line scans, and high-resolution XPS results indicate the presence of a Si-rich oxide accompanied by Fe, Cr, and Nb metal oxides in the outer layer of the powders. The flowability behavior is found to be induced by the particle size distribution, which can be attributed to the interparticle interactions and friction of particles with different sizes.