低温分相法制备高比表面积微/介孔SiOC陶瓷（英文）

Preparation of High Specific Surface Area Micro/Meso-porous SiOC Ceramics by the Low Temperature Phase Separation Method

以含氢聚硅氧烷(PHMS)、四甲基四乙烯基环四硅氧烷(Dvi4)和铂络合物为原料,采用热交联合成交联体,通过水蒸汽辅助热解促进前驱体低温分相及后续HF对SiOC陶瓷侵蚀基础上,获得高比表面积微/介孔SiOC陶瓷。采用XRD、FT-IR、SEM和BET等测试技术对试样的物相组成、化学键、微观结构、比表面积和孔径分布等进行了表征。实验结果表明,水蒸气能够促进前驱体低温分相,使SiOC陶瓷中生成Si-O-Si键、SiO_2纳米畴和SiO_2纳米晶,这些可以作为造孔剂而被HF侵蚀,从而提高了SiOC陶瓷的比表面积。在热解温度1300℃条件下,微/介孔SiOC陶瓷具有最大比表面积1845.5 m2/g,孔径分布2.0～10 nm。

Micro/meso-porous SiOC ceramics with high surface area and narrow pore size distribution were prepared by the low temperature phase separation method(namely water vapor assisted pyrolysis) followed by etching in hydrofluoric acid(HF) solution. The cross-linked body was made from hydrogen-containing polysiloxane(PHMS), tetramethyl-tetravinylcycletetrasiloxane(Dvi4) and Pt-complex by thermal cross-linking. Phase compositions, chemical bonds, microstructures, and specific surface area of the prepared SiOC ceramic were investigated by XRD, FT-IR, SEM, and BET, etc. Water vapor can promote the precursor to produce Si-O-Si bonds, SiO2-rich clusters, and SiO2 nanocrystals in SiOC ceramics. All of these species act as pore-forming substrate and can be etched away by HF. Water vapor injection and pyrolysis temperature have important effects on phase compositions, microstructures and specific surface area of SiOC porous ceramics, which have a maximum specific surface area of 1845.5 m2/g and pore size distribution of 2.0-10 nm at pyrolysis temperature of 1300℃.