Additive and pyrolysis atmosphere effects on polysiloxane-derived porous SiOC ceramics
Additive and pyrolysis atmosphere effects on polysiloxane-derived porous SiOC ceramics
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DOI：
10.1016/j.jeurceramsoc.2017.06.036
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发表时间：
2017-12-01
影响因子：
5.7
通讯作者：
Lu, Kathy
中科院分区：
文献类型：
--
作者：
Erb, Donald;Lu, Kathy
多孔氧化碳化硅（SiOC）是一种优异的超高表面积材料，它可以通过成分和添加剂改性在高温下保持稳定，具有很强的可定制性。在本研究中，通过使用不同的有机添加剂和热解气氛，在氢氟酸（HF）蚀刻后，以碱性聚硅氧烷（PSO）体系制备了块状SiOCs。添加剂通过影响SiO2纳米畴的形成来改变微观结构的演变。与Ar气氛热解相比，Ar+H2O气氛热解制备的SiOC陶瓷SiC含量明显降低，SiO2含量明显增加。热解过程中水蒸气的注入也会导致比表面积的急剧增加。添加10 wt%正硅酸四乙酯（TEOS）进行Ar + H2O热解，产生的比表面积为1953.94 m(2)/g，而在Ar中热解的碱性PSO的比表面积为880.09 m(2)/g。讨论了组成和相演变的基本过程，作为制造超高表面积材料的新途径。通过使用热解气氛和有机添加剂大幅增加比表面积的能力为高多孔SiOC陶瓷的加工提供了一条有前途的途径。(C) 2017 Elsevier Ltd.版权所有。
Porous silicon oxycarbide (SiOC) is emerging as a much superior ultrahigh surface area material that can be stable up to high temperatures with great tailorability through composition and additive modifications. In this study, bulk SiOCs were fabricated from a base polysiloxane (PSO) system by using different organic additives and pyrolysis atmospheres followed by hydrofluoric acid (HF) etching. The additives modify the microstructural evolution by influencing the SiO2 nanodomain formation. The SiOC ceramics contain significantly less SiC and more SiO2 with Ar+H2O atmosphere pyrolysis compared to Ar atmosphere pyrolysis. Water vapor injection during pyrolysis also causes a drastic increase in specific surface areas. The addition of 10 wt% tetraethyl orthosilicate (TEOS) with Ar + H2O pyrolysis produces a specific surface area of 1953.94 m(2)/g, compared to 880.09 m(2)/g for the base PSO pyrolyzed in Ar. The fundamental processes for the composition and phase evolutions are discussed as a novel pathway to creating ultrahigh surface area materials. The ability to drastically increase the specific surface area through the use of pyrolysis atmosphere and organic additives presents a promising processing route for highly porous SiOC ceramics. (C) 2017 Elsevier Ltd. All rights reserved.