• Title, Summary, Keyword: Polycarbosilane

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Synthesis of aluminum contained polycarbosilane and preparation of Si-Al-C-O nanocomposite fiber (Aluminum이 첨가된 polycarbosilane 합성 및 Si-Al-C-O 나노복합섬유 제조)

  • 신동근;류도형;김영희;김형래;정영근
    • Proceedings of the Materials Research Society of Korea Conference
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    • pp.240-240
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    • 2003
  • SiC 섬유의 고온강도를 향상시키기 위한 소결조제로 boron, aluminum 등을 사용할 수 있다. 본 연구에서는 폴리카보실란에 aluminum precursor를 첨가한 후 중합반응을 거쳐 Al-contained polycarbosilane을 합성하였다. 합성된 Al-contained polycarbosilane을 용융방사하여 섬유화 하고 열분해 공정을 통해 Si-Al-C-O 나노복합 섬유를 제조하였다. 먼저 aluminum butoxide와 polycarbosilane(commercial)을 200m1 xylene에 용해시켜 14$0^{\circ}C$에서 1시간 동안 reflux하였다. evaporator를 이용하여 xylene를 제거한 후 autoclave에서 25$0^{\circ}C$/30$0^{\circ}C$ 중합과정을 통해 가교결합 시켰다 이와 같이 합성된 시료는 ICP분석을 통해 aluminum 함량을 확인하였고 FT-IR(Fig.1) 및 GPC분석(Fig.2)으로부터 화학구조 및 분자량변화를 확인하였다. aluminum 첨가량이 증가함에 따라 Si-H/Si-$CH_3$의 결합크기의 비가 감소하였으며 이로부터 aluminum butoxide와 polycarbosilane의 가교결합이 이루어진 것으로 보이며 중합 후 분자량의 증가 또한 가교결합에 의한 결과로 사료된다 열무게감량(TGA) 측정 결과는 40$0^{\circ}C$부터 유기리간드의 분해가 일어나며 80$0^{\circ}C$이상에서 세라믹화 과정이 완료되었음을 알 수 있었다 또한 aluminum 첨가량이 증가함에 따라 세라믹 수율도 증가하였음을 확인하였다. 합성된 aluminum-contained polycarbosilane은 20$0^{\circ}C$에서 1시간 동안 불융화과정을 거쳐 환원 및 진공 분위기에서 고온 열처리하였으며 이로부터 얻어진 시료에 대해 XRD분석을 수행하였다. SEM과 TEM을 이용하여 미세구조를 관찰하였다.

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Synthesis of Polycarbosilane for SiC Precursor (II) (SiC의 Precursor Polycarbosilane의 합성 (II))

  • Han, Chul;Lee, Hyung-Bock;Chung, Yun-Joong
    • Journal of the Korean Ceramic Society
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    • v.25 no.5
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    • pp.518-522
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    • 1988
  • Polycarbosilane was synthesized from polydimethylsilane at 42$0^{\circ}C$, pyrolysis temperature with various times And IR, NMR, UV, and GPC were detected. Average molecular weight Mn was increased proportionally with the reaction time. Average molecular weight of polycarbosilane was about 700(n=20), which has chain structure and the product yield was 72%.

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Preparation and Reaction of Silyltriflate (Silyltriflate의 제조와 반응)

  • Kim, Chungkyun;Park, Eunmi;Jung, Inkyung;Joo, Kwangsuk
    • Journal of the Korean Chemical Society
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    • v.39 no.10
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    • pp.783-788
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    • 1995
  • Silyltriflates are obtained by reaction of the corresponding phenyl derivatives with CF3SO3H. The reaction of silyltriflate with allylmagnesium bromide produced the allylated silane derivatives R2SiHCH2CH=CH2 (R=Me, Ph). They are formed under mild condition with Pt catalysis to polycarbosilane. The cleavage of silicon-phenyl bonds of polysilane by CF3SO3H leads to triflate derivatives of polycarbosilane.

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Characterization of SiC Fiber Derived from Polycarbosilanes with Controlled Molecular Weight (분자량이 조절된 폴리카보실란으로부터 제조한 SiC Fiber의 특성분석)

  • Shin, Dong-Geun;Riu, Doh-Hyung;Kim, Younghee;Kim, Hyung-Rae;Park, Hong-Sik;Kim, Hyoun-Ee
    • Journal of the Korean Ceramic Society
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    • v.42 no.8
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    • pp.593-598
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    • 2005
  • Polycarbosilane was synthesized by the Kumada rearrangement of polydimethylsilane in the presence of zeolite (ZSM-5) as a catalyst at $350^{\circ}C$. The prepared polycarbosilane had very low molecular weight ($M_w=500$), so that it was not suitable to fabricate SiC fiber by melt spinning. Further polymerization of PCS was conducted around $400^{\circ}C$ to obtain spinnable polycarbosilane. After polymerization, the polycarbosilanes were isolated by distillation according to the molecular weight distributions. The PCS with a controlled molecular weight distribution was spun into continuous polycarbosilane green fibers. The PCS green fiber was successfully transformed into silicon oxycarbide fiber. The room temperature strength of the SiC fiber was around 1.5 - 1.8 GPa. The oxidation behavior and the tensile strength after oxidation were also evaluated.

Sintering of TiB2 with Polycarbosilane (Polycarbosilane 첨가에 의한 TiB2의 소결)

  • Lee, Kwang-Jung;Kang, Shin-Hyuk;Kim, Deug-Joong
    • Journal of the Korean Ceramic Society
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    • v.42 no.8
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    • pp.588-592
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    • 2005
  • The effect of SiC additive on the densification behavior and microstructural change of $TiB_2$ ceramics was investigated. The infiltration and direct mixing with polycarbosilane (PCS), which was converted to SiC by pyrolysis during sintering, were used for the addition of SiC. The addition of Fe enhanced the densification of $TiB_2$, but which resulted in exaggerated grain growth. However, the addition of PCS enhanced the densification and suppressed the exaggerated grain growth of $TiB_2$. Moreover, the addition of PCS using direct mixing was more effective for suppress of grain growth as compare to the addition of PCS using infiltration.

Formation of TiB2-SiC Ceramics from TiB2-Polycarbosilane Mixtures (Polycarbosilane을 이용한 TiB2-SiC 세라믹의 형성)

  • Kang, Shin-Hyuk;Lee, Dong-Hwa;Kim, Deug-Joong
    • Journal of the Korean Ceramic Society
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    • v.45 no.9
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    • pp.544-548
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    • 2008
  • The formation of $TiB_2-SiC$ ceramics from $TiB_2$-Polycarbosilane (PCS) mixtures was investigated. The powder mixture of $TiB_2$ with PCS was pressed at $300^{\circ}C$ with 200 MPa and sintered at $1700{\sim}2000^{\circ}C$ for 1 h in a flowing Ar atmosphere. The sintered density of $TiB_2$ with PCS is 93.7% after sintering at $2000^{\circ}C$ for 1 h, which is slightly smaller than that of the specimen without PCS. The microstructure of $TiB_2$ with PCS consists of small and uniform $TiB_2$ particles with well dispersed SiC particles derived from PCS. It is believed that the addition of PCS was effective to suppress the grain growth of $TiB_2$.