• 제목/요약/키워드: whisker

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The effect of impact directions and angels on erosion behavior of undirectionally oriented sillicon nitride (충돌 방향과 각도가 일방적으로 배향된 질화규소의 Erosion 거동에 미치는 영향)

  • Cho, Chang-Hee;Choi, Hyun-Joo;Lim, Dae-Soon;Jung, Jung-Sik;Park, Dong-Soo
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 2001.11a
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    • pp.88-95
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    • 2001
  • Silicon nitride based ceramics reinforced with 3wt% Si$_{3}$N$_{4}$ whisker was prepared by tape casting to investigate the effect of microstructure on erosion behaviors. Hardness and fracture toughness were measured with prepared specimens. A gas blast type erosion tester was used to examine the erosion behavior of the specimens with different impact directions and angles. The erosion rate increases with increasing impact angle. Erosion rate of the silicon nitride ceramics also depends on the grain orientations, The erosion rate was lowered when impaction direction was parallel to the grain orientation This result was explained by the crack deflection and bridging due to the grain orientation.

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Fabrication of a Complex-Shaped Silicon Nitride Part with Aligned Whisker Seeds Using LOM Technique

  • Park, Dong-Soo;Cho, Byung-Wook
    • Journal of the Korean Ceramic Society
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    • v.40 no.10
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    • pp.931-935
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    • 2003
  • A complex-shaped part was successfully fabricated by Laminate Object Manufacturing (LOM) technique using silicon nitride tape with aligned silicon nitride whisker seeds. The ceramic tape was cut using a commercial cutting plotter according to the cross section drafts generated by slicing a 3-D model, and then the tapes were stacked sequentially. In order to improve adhesion between the tapes, stacking was performed under vacuum. After binder burnout, the part was encapsulated using latex emulsion and was cold isostaically pressed under 250 ㎫. It was sintered to 98.5% TD at 2148 K for 4 h under 2 ㎫ nitrogen pressure.

Characterization of Mullite Whiskers Synthesized with Compostion of Al(OH)3-SiO2-AlF3 (Al(OH)3-SiO2-AlF3 조성으로 합성된 뮬라이트 휘스커의 특성평가)

  • Lee, Hong-Lim;Kang, Jong-Bong
    • Journal of the Korean Ceramic Society
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    • v.43 no.5 s.288
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    • pp.320-326
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    • 2006
  • Mullite whiskers were synthesized by a vapor-solid reaction with $Al(OH)_3-SiO_2-AlF_3$. The heat treatment temperature did not affect the shape of mullite whisker but the composition change resulted in different sizes. The first one was $30-50{\mu}m$ in size with the aspect ratio of 60 and above, and the second one was $600{\mu}m$ and below in size with the aspect ratio of 15 and below. The $Al_2O_3$ content in formed mullite whisker was 73.57-80.29 wt%, which is high $Al_2O_3$ content composition. The Young's modulus and the hardness measured by nano-indentation method were 136.7 GPa and 19.81 GPa, respectively.

Synthesis of Al2O3/SiC Whisker (Al2O3/SiC Whisker원료 합성)

  • Chung, K.C.;Joo, K.;Chun, Y.S.;Orr, K.K.;Kim, E.H.;Lee, S.K.
    • Journal of the Korean Ceramic Society
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    • v.26 no.2
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    • pp.167-170
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    • 1989
  • Al2O3/SiC composite-material was synthesized by the birth-spread mechanism through the carbothermal reduction reaction of SiO2 in Ha-Dong Kaolin with carbon powder under H2 gas atmosphere at 1300~140$0^{\circ}C$. Average diameter of synthesized SiC whiskers were 1${\mu}{\textrm}{m}$ and aspect ratio (c/a) was 10~100. Al2O3 particles and SiC whiskers were mixed homogeneously in the reacted pellet.

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Studies on the Synthesis of Potassium Hexatitanate and Manufacturing Thin Film Type Matrix (Potassium hexatitanate의 합성과 박막형 Matrix 제작에 관한 연구)

  • 심중표;이홍기;이주성
    • Journal of the Korean institute of surface engineering
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    • v.26 no.6
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    • pp.299-306
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    • 1993
  • The characteristic of synthesized potassium hexatitanate and manufacturing of thin film type matrix for battery was studied. After ball milled the mixture with 1:4 of $K_2CO_3$ and TiO2, mixsture was sintered at 85$0^{\circ}C$ and its product was confirmed with XRD. Adding the PTFE to the obtained potassium hexatitanate according to there various ball-mill time to control its particle size, thin film type matrix was manufactured. The high-est wettability of 50% was found with 12 hour ball milled powder containing 10w/o of PTFE and also it shown good mechanical properties. The matrix with $K_2O$$\cdot$$6TiO_2$ whisker shown 170% of wettability. Thed char-acteristics of matrix made by whisker and powder mixture were compared with the investigation of bubbled pressure and pore size distribution to improve its mechanical properties.

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