• Title/Summary/Keyword: 질화규소

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Microstructural Development of $Si_3N_4$ Ceramics Containing Aligned ${\beta}-Si_3N_4$ Whisker Seeds (배향된 질화규소 휘스커 종자를 함유한 질화규소 세라믹스의 미세구조에 관한 연구)

  • Bae, Byoung-Chan;Park, Dong-Soo;Seo, Won-Chan;Bang, Kook-Soo;Park, Chan
    • Journal of Ocean Engineering and Technology
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    • v.23 no.5
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    • pp.32-38
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    • 2009

  • Silicon nitride samples with aligned whisker seeds were prepared with different amounts of yttria and alumina as the sintering additives. Their sintering behaviors and the microstructural developments between $1850^{\circ}C$ and $2050^{\circ}C$ were examined. The sample with larger amount of the sintering additives showed faster densification and grain growth. Even though addition of the aligned whisker seeds slightly retarded densification of silicon nitride, it improved the flexural strength and the fracture toughness. Both the flexural strength and the fracture toughness of silicon nitride with the aligned whisker seeds were increased as the amount of the sintering additives was increased.

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Quasi-Plasticity of $Si_3N_4$-BN Composites (질화규소-질화붕소 복합재료의 준소성 특성)

  • Lee, Gi-Seong;Lee, Seung-Geon;Kim-kim, Do-Gyeong
    • Korean Journal of Materials Research
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    • v.8 no.3
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    • pp.200-205
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    • 1998

  • The nature, degree, and evolution of contact damage from Hertzian contacts in silicon nitride-boron nitride composites($Si_3N_4-BN$) are investigated as a function of boron nitride content. The strong deviations of indentation stress-strain from elastic response indicate exceptional plasticity in $Si_3N_4-BN$. The absence of ring cracks or cone cracks on the surfaces is observed, indicating a high damage tolerance. Subsurface quasi- plastic deformation by shear stress is considerable and microdamage is widely distributed within the region below the contact. Shear faults associated with local microfailures play a precursor role in plasticity of this material. When boron nitride content increases, $Si_3N_4-BN$ becomes softer and more quasi-plastic.

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