• 제목/요약/키워드: Whiskers

검색결과 159건 처리시간 0.025초

에치슨법에 의한 탄화규소 휘스카의 성장과 특성분석 (Formation and Characterization of Silicon Carbide Whiskers by Acheson Method)

  • 주한용;김형준
    • 한국세라믹학회지
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    • 제27권1호
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    • pp.136-146
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    • 1990
  • Whiskers of SiC were grown from the mixture of silica and graphite powders by Acheson method(direct heating method). The structrua, morphological and chemical characterizations have been performed by X-ray diffractometer(XRD), transmission electron microscopy(TEM), optical microscopy(OM), scanning electron microscopy(SEM), X-ray photoelectron spectroscopy(XPS) and energy dispersive spectrometer(EDS). The growth mechanism of SiC whiskers is also discussed.

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Fabrication and Characterization of Alumina Matrix Composites Reinforced with SiC whiskers

  • Han, Byung-Dong;Park, Dong-Soo
    • The Korean Journal of Ceramics
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    • 제5권1호
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    • pp.12-18
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    • 1999
  • Alumina matrix composites reinforced with up to 20vol% of aligned SiC whiskers were fabricated by tape casting and hot pressing. Alumina composited with randomly distribution SiC whiskers were also fabricated in order to investigate the effect of whisker alignment on properties of the composites. XRD and optical microscopy were used to examine the whisker orientation. The fracture toughness increased with increasing whisker content, and it was higher in the direction normal to the tape casting direction.

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수염 촉각 센서를 이용한 물체 위치 판별 그리고 이에 따른 로봇의 상대적 위치 제어 방법 (Tactile localization Using Whisker Tactile Sensors)

  • 김대은;랄프몰러
    • 대한전자공학회:학술대회논문집
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    • 대한전자공학회 2008년도 하계종합학술대회
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    • pp.1061-1062
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    • 2008
  • Rodents demonstrate an outstanding capability for tactile perceptions using their whiskers. The mechanoreceptors in the whisker follicles are responsive to the deflections or vibrations of the whisker beams. It is believed that the sensor processing can determine the location of an object in touch, that is, the angular position and direction of the object. We designed artificial whiskers modelling the real whiskers and tested tactile localization. The robotic system needs to adjust its position against an object to help the shape recognition. We show a robotic adjustment of position based on tactile localization. The behaviour uses deflection curves of the whisker sensors for every sweep of whiskers and estimates the location of a target object.

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SiC 휘스커 보강 $Al_2$O$_3$-SiC 복합체의 열간특성 (Thermal Characteristics of SiC Whisker Reinforced $Al_2$O$_3$-SiC Composite)

  • 김윤주;나용한
    • 한국세라믹학회지
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    • 제35권1호
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    • pp.1-4
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    • 1998
  • SiC whisker reinforced Al2O3-SiC composite was fabricated by reaction synthesis method whish is cost ef-fective and allows good dispersion of whiskers. Fracture strength at room temperature showed the highest value with 150$0^{\circ}C$ reaction temperature because a lot of SiC whiskers was formed. Fracture strength at 135$0^{\circ}C$ did not show big differences with reaction temperature due to agglomeration of whiskers and formation of sil-icon oxynitride during hot MO(modulus of rupture) test probably promoting grain boundary sliding.

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Effect of Silicon Nitride Whisker Content on the Flexural Strength of Silicon Nitride-Boron Nitride-Silicon Carbide Multi-Layer Composites

  • Park, Dong-Soo;Cho, Byung-Wook
    • 한국세라믹학회지
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    • 제40권9호
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    • pp.832-836
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    • 2003
  • Multi-layer ceramic composites were prepared by tape casting followed by hot pressing using silicon nitride layer with silicon nitride whiskers, silicon nitride layer with silicon carbide particles and boron nitride-alumina layer. The whiskers were aligned during the casting. As the whisker content of the silicon nitride layer was increased up to 10 wt%, the flexural strength of the multi-layer composite was increased. However, further increase of the whisker content in the layer resulted in a rapid decrease of the strength of the composite. The results suggest that the strength of multi-layer ceramic composite showing non-catastrophic failure behavior can be significantly improved by incorporating the aligned whiskers in the layers.

SiC 휘스커 및 TiC 입자 강화 알루미나 복합재료의 기계적 성질과 미세조직 (Mechanical Properties and Microstructures of Alumina Composites Reinforced with SiC Whiskers and TiC Particles)

  • 이영규;김준규;조원승;최상욱
    • 한국세라믹학회지
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    • 제37권8호
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    • pp.792-798
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    • 2000
  • Alumina composites reinforced with SiC whiskers only or combinded with TiC particles were prepared by hot-pressing at 1850$^{\circ}C$ for 1h. The mechanical properties and microstructures of composites were investigated in this study. By of addition either 20 vol% SiC whiskers or 20 vol% TiC particles, the flexural strength fo alumina was increased from 360 MPa to 650 MPa or 730 MPa, respectively, and the KIC was also increased from 3.5 MPa$.$m1/2 to 5.5MPa$.$m1/2 or 4.4MPa$.$m1/2, respectively. In the case of composites with 20 vol% SiC whiskers and 2 vol% TiC particles. The flexural strength and KIC showed relatively high value of 800 MPa and 5.3MPa$.$m1/2, respectively. The improvement of mechanical properties was considered to be due to both the smaller average grain size and the crack deflection.

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석탄재를 이용한 뮬라이트 휘스커 고다공성 세라믹 제작 (Fabrication of High Porous Ceramic with Mullite Whisker from Fly Ash)

  • 신철;황광택;김응수;한규성;최정훈;김진호
    • 한국재료학회지
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    • 제32권5호
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    • pp.258-263
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    • 2022
  • Porous ceramics have the advantages of low density, low thermal conductivity, and excellent mechanical properties. Among porous ceramic manufacturing methods, the replica template method allows the easy manufacturing of porous filters with the highest porosity and pores of the desired size, but it also has the disadvantage that the resulting filters have low mechanical strength. To overcome this shortcoming, mullite (3Al2O3·2SiO2) whiskers, which have excellent thermal stability and high mechanical strength, were introduced in porous ceramic structure. The mullite whiskers were synthesized using a composition of Al2O3, flyash and MoO3. The morphologies and crystal structures of the mullite whiskers with MoO3 contents were investigated in detail. When the porous ceramic with mullite whiskers was fabricated using 20 wt% MoO3 catalyst the most uniform microstructure was obtained, and the mullite whiskers showed the highest aspect ratio of 47.03. The porosity and compressive strength of the fabricated porous ceramic were 82.12 % and 0.83 MPa, respectively.

제어된 기공을 이용한 질화규소 휘스커의 성장 (Growth of silicon nitride whiskers using tailored pores)

  • 김창삼;한경섭;김신우
    • 한국결정성장학회지
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    • 제15권2호
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    • pp.61-67
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    • 2005
  • 본 연구에서는 질화규소의 소결 과정에서 인위적으로 형성시킨 기공내부에 질화규소의 휘스커를 성장시키는 새로운 방법을 시도하였다. 실험변수로는 기공의 크기, 기공률 및 질소압력을 사용하였다. 기공률이 14vol%와 27vol%로 낮은 경우에는 질화규소 휘스커가 기공내부에 잘 성장되었으나 39vol%와 50vol%로 기공률이 증가된 경우에는 휘스커가 거의 성장하지 않았다. 한편 기공의 크기와 질소압력은 기공내부에 질화규소 휘스커의 성장에 거의 영향을 주지 않았고, 소결과정에 기공 내에 휘스커를 성장시키는 중요한 조건은 고립된 형태의 닫힌 기공을 유지하는 것임을 알았다.

Vacuum Hot Pressing 조건이 $SiC_w$/2124AI 금속복합재료의 기계적 성질 및 미세구조에 미치는 영향 (Effects of Vacuum Hot Pressing Conditions on Mechanical Properties and Microstructures of $SiC_w$/2124Al Metal Matrix Composites)

  • 홍순형
    • 한국분말재료학회지
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    • 제1권2호
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    • pp.159-166
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    • 1994
  • The variation of the microstructures and the mechanical properties with varying vacuum hot pressing temperature and pressure was investigated in PyM processed 20 vol%) SiCw/ 2124Al composites. As increasing the vacuum hot pressing temperature, the aspect ratio of whiskers and density of composites increased due to the softening of 2124Al matrix with the increased amount of liquid phase. The tensile strength of composite increased with increasing vacuum hot pressing temperature up to $570^{\circ}C$ and became saturated above $570^{\circ}C$, To attain the high densification of composites above 99%, the vacuum hot pressing pressure was needed to be above 70 MPa. However, the higher vacuum hot pressing pressure above 70 MPa was not effective to increase the tensile strength due to the reduced aspect ratio of SiC whiskers from damage of whiskers during vacuum hot pressing. A phenomenological equation to predict the tensile strength of $SiC_w$/2124AI composite was proposed as a function including two microstructural parameters, i.e. density of composites and aspect ratio of whiskers. The tensile strength of $SiC_w$/2124AI were found more sensitive to the porosity than other P/M materials due to the higher stress concentration and reduced load transfer efficiency by the pores locating at whisker/matrix interfaces.

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Whisker Growing Assisted 화학침착 공정으로 제조된 SiCf/SiC 복합체의 파괴거동과 기계강도 평가 (Fracture Behaviors and Mechanical Properties of SiCf/SiC Composites Prepared by the Whisker Growing Assisted CVI Process)

  • 강석민;김원주;윤순길;박지연
    • 한국세라믹학회지
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    • 제46권5호
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    • pp.484-487
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    • 2009
  • $SiC_f$/SiC composites with whiskers and pyrolytic carbon (PyC) coated whiskers in the matrix were fabricated for enhancement of the fracture behaviors by the whisker growing assisted chemical vapor infiltration (WA-CVI) process, respectively. $SiC_f$/SiC composites were also prepared by the conventional CVI process as reference material. The mechanical properties and fracture behaviors were analyzed by comparison of the two types of composites prepared by WA-CVI and conventional CVI. The densities of $SiC_f$/SiC composites were in the range of $2.6{\sim}2.65g/cm^3$. The flexural strengths of composite with whiskers and with those coated by PyC were 650 MPa and 600 MPa, respectively. The tensile strength of composites with whiskers was ${\sim}285$ MPa.