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RISS 인기검색어
- 검색키워드
- 저자 : Quoc Dat Nghiem, (검색결과 21 건)
- 무료
- 기관 내 무료
- 유료
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Preparation of Mesoporous SiCBN Ceramic Templated by Mesoporous Carbon
Quoc Dat Nghiem,,류향임,김동표 한국세라믹학회 2007 한국세라믹학회지 Vol.44 No.7
prepared from borazine and 2,4,6-trimethyl-2,4,6-trivinylcyclotrisilazane via a hydroboration reaction, into a mesoporous carbo n(CMK-3) as a hard template. This was followed by pyrolysis at 1400oC under nitrogen gas and subsequent oxidative removal ofthe carbon template without chemical etching. The prepared mesoporous SiCBN ceramic was characterized by a small-angleXRD, TEM, and BET surface area. The resulting mesoporous SiCBN ceramic revealed a BET surface area of 275 m2g1 and apore volume of 0.8cm3 g with no crystallization.
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Preparation of Mesoporous SiCBN Ceramic Templated by Mesoporous Carbon
Nghiem, Quoc Dat,Ryoo, Hyang-Im,Kim, Dong-Pyo The Korean Ceramic Society 2007 한국세라믹학회지 Vol.44 No.7
Well-ordered mesoporous SiCBN ceramics have been successfully synthesized by infiltrating a polymeric precursor, which was prepared from borazine and 2,4,6-trimethyl-2,4,6-trivinylcyclotrisilazane via a hydroboration reaction, into a mesoporous carbon (CMK-3) as a hard template. This was followed by pyrolysis at $1400^{\circ}C$ under nitrogen gas and subsequent oxidative removal of the carbon template without chemical etching. The prepared mesoporous SiCBN ceramic was characterized by a small-angle XRD, TEM, and BET surface area. The resulting mesoporous SiCBN ceramic revealed a BET surface area of $275 m^2g^{-1}$ and a pore volume of $0.8 cm^3 g$ with no crystallization.
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Synthesis of heat-resistant mesoporous SiOC ceramic and its hydrogen adsorption
Nghiem, Quoc Dat,Cho, Sung June,Kim, Dong-Pyo Royal Society of Chemistry 2006 Journal of materials chemistry Vol.16 No.6
<P>High-temperature stable mesoporous SiOC ceramic was prepared by the self-assembling reaction between an anionic surfactant and the inorganic precursor <I>N</I>-trimethoxylsilylpropyl-<I>N</I>,<I>N</I>,<I>N</I>-trimethylammonium chloride, followed by calcination at 600 °C under nitrogen. The preferred structure was adjusted by varying the co-structure directing agent (CSDA)/surfactant ratio, which allows for better control of the nanoscale morphologies of mesoporous SiOC. The microstructural change was thoroughly investigated by BET, SAXS, TEM, and <SUP>29</SUP>Si NMR. The obtained SiOC products exhibited a high surface area, up to 1762 m<SUP>2</SUP> g<SUP>−1</SUP>, with uniform pore size distribution, which was only reduced to 1403 m<SUP>2</SUP> g<SUP>−1</SUP> when exposed to 800 °C in air. In particular, the mesoporous product showed 1.1 wt% of H<SUB>2</SUB> sorption at 298 K and 25 atm, which could be extended into hydrogen storage materials.</P> <P>Graphic Abstract</P><P>Mesoporous SiOC ceramics with a high surface area (1762 m<SUP>2</SUP> g<SUP>−1</SUP>), which are thermally stable even at temperatures of up to 800 °C, were synthesized using an anionic surfactant as a template for applications such as hydrogen storage. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=b514078a'> </P>
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Nghiem, Quoc Dat,Pham, Anh Tuan,Kim, Dong Pyo Trans Tech Publications, Ltd. 2006 Materials science forum Vol.510 No.-
<P>Microelectromechanical systems (MEMS) including microchemical devices have been widely concerned, in particular, when made of an extremely stable ceramic material for their use at harsh conditions. SiCBN preceramic polymer was derived from borazine (B3N3H6) modified allylhydridopolycarbosilane (AHPCS) via hydroboration of allyl groups with B-H groups at 0oC for 24 h by following the standard Schenk technique. The extent of polymer-to-ceramic conversion with an ultimate ceramic yield of 92 wt% was investigated by simultaneous TGA, 1H, 13C-NMR, IR, and XRD measurements. The polymer-derived SiCBN ceramic remained as an amorphous solid up to 1400oC. The ceramic product obtained after pyrolysis at 1000-1400oC exhibited excellent oxidation resistance in air. In addition, ceramic microstructures were fabricated by employing soft lithographic technique.</P>
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