• Title/Summary/Keyword: Preceramic

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Preceramic Polymer Technology for High Temperature Ceramic Composite and its Application (초고온복합소재용 프리세라믹폴리머 합성 및 응용기술)

  • Lee, Yoonjoo;Kim, Younghee;Bae, Seong Gun;Lee, Hyeon Myoung;Cho, Kwang Youn;Kwon, Woo Teck;Kim, Soo Ryong;Riu, Doh Hyung;Shin, Dong Geun
    • Composites Research
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    • v.30 no.2
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    • pp.102-107
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    • 2017
  • The preceramic polymer can realize a variety of complex ceramic structures that can not be obtained by conventional ceramic processes. Polycarbosilane, which is a typical preceramic polymer, can control the molecular structure, molecular weight and molecular weight distribution for preparing complex morphology and microstructure of SiC ceramics, including SiC fiber. In this paper, synthesis and molecular structure control technique of polycarbosilane is explained. The silicon carbide fiber prepared by melt spinning, stabilization and heat treatment, and ceramic fiber composites technology made by PIP process are also discussed. In addition, we introduce an example of the development of a complex silicon carbide material such as a silicon carbide hollow fiber having a nanoporous structure.

Advancements in Polymer-Filler Derived Ceramics

  • Greil, Peter
    • Journal of the Korean Ceramic Society
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    • v.49 no.4
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    • pp.279-286
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    • 2012
  • Microstructure tailoring of filler loaded preceramic polymer systems offers a high potential for property improvement of Si-based ceramics and composites. Advancements in manufacturing of bulk materials by controlling microstructure evolution during thermal induced polymer-ceramic transforma-tion and polymer-filler reactions will be presented. Rate controlled pyrolysis, multilayer gradient laminate design and surface modification by gas solid reaction are demonstrated to yield ceramic components of high fractional density and superior mechanical properties. Emerging fields of applications are presented.

Synthesis and Characteristics of Zirconium Hybridized Polycarbosilane (지르코늄 혼성 폴리카르보실란의 합성 및 특성)

  • Kang, Phil-Hyun;Yang, Hyun-Soo
    • Applied Chemistry for Engineering
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    • v.9 no.6
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    • pp.791-797
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    • 1998
  • As organosilicon based preceramic polymer, new zirconium hybridized polycarbosilane having a good thermal stability and forming stage was synthesized. Oxidative stability(infusibility) and mechanical property of this polymer during the thermal curing process and heat treatment were examined. Prepared zirconium hybridized polycarbisilane (PZC) was spun into fiber at $250{\sim}270^{\circ}C$. Spinnability of PZC polymer having a molecular weight of 1000 to 1400 and having a dispersity<2 was good. The thermal curing process of the PZC fiber was done at 140 to $200^{\circ}C$. The mechanical properties of PZC ceramic fiber depend on curing temperature of PZC as precursor of PZC ceramic fiber. It was found that the optimum curing temperature was variable with the molecular weight of PZC. The cured PZC fiber need constant gel fraction to have good tensile strength.

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The Oxidation of Polymethylsiloxane/MoSi$_2$/SiC/Si-Derived Ceramic Composite Coatings

  • Moon, Jae-Jin;Lee, Dong-Bok;Kim, Deug-Joong
    • Journal of the Korean institute of surface engineering
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    • v.36 no.1
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    • pp.85-88
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    • 2003
  • By utilization of preceramic polymer of polymethylsiloxane (PMS), a $MoSi_2$SiOC/SiC ceramic composite was fabricated. The prepared composite displayed superior high temperature oxidation resistance by forming $SiO_2$ on the surface. The thin $SiO_2$ layer had some surface cracks, but they had not adversely deteriorated the oxidation resistance. The composite fabrication method employed in this study can be applied to protect any possible substrate material from aggressive oxidative attack, if the composite were coated on the substrate material.

Preparation of Si(Al)ON Precursor Using Organoaluminum Imine and Poly (Phenyl Carbosilane), and the Compositional Change of the Film with Different Heat Treatment Condition

  • Lee, Yoonjoo;Shin, Dong-Geun;Kwon, Woo Teck;Kim, Soo Ryong;Kim, Younghee
    • Journal of the Korean Ceramic Society
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    • v.52 no.4
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    • pp.243-247
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    • 2015
  • Si(Al)ON precursor was synthesized by formation of new Si-N bond using organoaluminum imine and liquid type poly(phenyl carbosilane). It was decomposed between $200-600^{\circ}C$, and the ceramic yield was 51% after pyrolysis. 150 - 200 nm in thickness of coating film was obtained by spin coating method. The precursor was easily oxidized during process because it was unstable in air. However the oxygen content was limited to 0.5 - 0.7 to silicon in heat treatment step. Even though the content of nitrogen was decreased by pyrolysis, Al-N and Si-N bonds were formed in ammonia atmosphere, and Si(Al)ON film was formed with 0.2 in content to silicon.

Reaction Bonded Si3N4 from Si-Polysilazane Mixture (규소 고분자 복합체를 이용한 반응소결 질화규소)

  • Hong, Sung-Jin;Ahn, Hyo-Chang;Kim, Deug-Joong
    • Journal of the Korean Ceramic Society
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    • v.47 no.6
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    • pp.572-577
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    • 2010
  • Reaction-bonded $Si_3N_4$ has cost-reduction merit because inexpensive silicon powder was used as a start material. But its density was not so high enough to be used for structural materials. So the sintered reaction-bonded $Si_3N_4$techniques were developed to solve the low density problem. In this study the sintered reaction-bonded $Si_3N_4$ manufacturing method by using polymer precursor which recently attained significant interest owing to the good shaping and processing ability was proposed. The formations, properties of reaction-bonded $Si_3N_4$ from silicon and polysilazane mixture were investigated. High density reaction-bonded $Si_3N_4$ was manufactured from silicon and silicon-containing preceramic polymers and post-sintering technique. The mixtures of silicon powder and polysilazane were prepared and reaction sintered in $N_2$ atmosphere at $1350^{\circ}C$ and post-sintered at 1600~$1950^{\circ}C$. Density and phase were analyzed and correlated to the resulting material properties.

High-Temperature Oxidation Behavior of TiN-Ti5Si3 Ceramic Composites Manufactured by Polymer Pyrolysis (고분자 열분해 방법으로 제조된 TiN-Ti5Si3 세라믹 복합체의 고온 산화 거동)

  • Kim, Beom-Seob;Kim, Deug-Joong;Lee, Dong-Bok
    • Journal of the Korean Ceramic Society
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    • v.43 no.8 s.291
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    • pp.486-491
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    • 2006
  • A new $TiN-Ti_5Si_3$ bulk composite was synthesized from preceramic, inorganic polymer (methylpolysilsesquioxane) and $TiH_2$ filler powders via polymer pyrolysis. Using this process, ceramics with high melting points can be produced relatively easily to a near net shape. The $TiN-Ti_5Si_3$ composite oxidized slowly during heating to $1000^{\circ}C$. During heating at the temperatures of at 700 and $800^{\circ}C$, TiN oxidized to Rutile-$TiO_2$ whereas $Ti_5Si_3$ resisted to oxidation. The oxide scale formed consisted primarily of $TiO_2$ containing $Ti_5Si_3$.

The Synthesis and Pore Property of Hydrogen Membranes Derived from Polysilazane as Inorganic Polymer (무기 고분자인 폴리실라잔을 이용한 수소 분리막의 합성 및 기공특성)

  • Kwon, Il-Min;Song, In-Hyuck;Park, Young-Jo;Lee, Jae-Wook;Yun, Hui-Suk;Kim, Hai-Doo
    • Journal of the Korean Ceramic Society
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    • v.46 no.5
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    • pp.462-466
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    • 2009
  • We investigated the pore properties of inorganic membranes applied for hydrogen separation industry. Inorganic membranes were derived from polysilazanes. The thermal reactions involved were studied using thermogravimetry(TG) and IR spectroscopy(FTIR) of the solids. To determine the thermal effect of pore properties, polysilazanes were pyrolysed in inert atmosphere. Pore volume and BET surface area showed the maximum value at a pyrolysis temperature of $500^{\circ}C$. For amorphous SiCN membrane derived from polysilazanes, selectivity of $H_2/N_2$ was 4.81 at $600^{\circ}C$.

Ceramic Foams by the Self-Blowing of Polymer (고분자의 자체발포를 이용한 세라믹 다공질체)

  • 백종원;김득중
    • Journal of the Korean Ceramic Society
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    • v.41 no.7
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    • pp.555-559
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    • 2004
  • Ceramic foams were prepared by a self-blowing process of a polysiloxane with A1$_2$O$_3$ as a filler. The release of water and ethanol vapor during the condensation reaction of the polymer triggered the pores in the polymer melt. The size. interconnectivity and shape of the pores in the ceramic foams were strongly dependent on the viscosity of the polymer melt, which could be varied by the content and size oi the filler. When the content of the filler inceased and the size of the filler decreased. the size of the pores were decreased and the thickness between the pores were increased. In the addition, the viscosity of polymer melt increased by the pretreatment at 130$^{\circ}C$ for Ire intermolecular cross linking thereby stabilizing the foam structure. The density and compressive strength of the ceramic foams were affected by the heating rate during the blowing process.

Fabrication and Characterization of Macro/Mesoporous SiC Ceramics from SiO2 Templates (실리카 주형을 이용한 메크로/메조다공성 탄화규소 세라믹의 제조와 비교특성)

  • ;Hao Wang
    • Journal of the Korean Ceramic Society
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    • v.41 no.7
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    • pp.528-533
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    • 2004
  • Macroporous SiC with pore size 84∼658 nm and mesoporous SiC with pore size 15∼65 nm were respectively prepared by infiltrating low viscosity preceramic polymer solutions into the various sacrificial templates obtained by natural sedimentation or centrifuge of 20∼700 nm silica sol, which were subsequently etched off with HF after pyrolysis at 1000∼140$0^{\circ}C$ in an argon atmosphere. Three-dimensionally long range ordered macroporous SiC ceramics derived from polymethylsilane (PMS) showed surface area 584.64$m^2$g$^{-1}$ when prepared with 112nm silica sol and at 140$0^{\circ}C$, whereas mesoporous SiC from polycarbosilane (PCS) exhibited the highest surface area 619.4 $m^2$g$^{-1}$ with random pore array when prepared with 20-30 nm silica sol and at 100$0^{\circ}C$. Finally, tile pore characteristics of porous SiC on the types of silica sol, polymers and pyrolytic conditions were interpreted with the analytical results of SEM, TEM, and BET instruments.