Out-of-furnace oxidation of SiCN polymer-derived ceramic aerogel pyrolized at intermediate temperature (600–800 °C)
Out-of-furnace oxidation of SiCN polymer-derived ceramic aerogel pyrolized at intermediate temperature (600–800 °C)
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DOI：
10.1016/j.jeurceramsoc.2015.10.038
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发表时间：
2016-02
影响因子：
5.7
通讯作者：
Emanuele Zera;W. Nickel;S. Kaskel;G. Sorarù
中科院分区：
文献类型：
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作者：
Emanuele Zera;W. Nickel;S. Kaskel;G. Sorarù
研究了聚硅氮烷/二乙烯基苯气凝胶从聚合物到陶瓷的转变，形成 SiCN 气凝胶。陶瓷前体样品是通过将市售的聚硅氮烷与二乙烯基苯在高度稀释的溶液中交联而获得的。使用CO2对湿凝胶进行超临界干燥，得到预陶瓷气凝胶。通过热重分析（原位测量）和测量管式炉中热解样品冷却至室温后的重量变化（非原位测量），研究了流动氩气中热解过程中的重量变化。通过红外光谱跟踪结构转变，同时通过氮吸附分析研究微观结构的变化。结果表明，样品在中间温度（即 600–800 °C 左右）热解，与实验室气氛反应，形成 Sisingle bondO 键和 Sisingle bondOH 部分。这种炉外氧化导致热解陶瓷的氧含量不受控制地增加，最终降低样品的微孔率及其稳定性。
The polymer-to-ceramic transformation of a polysilazane/divinylbenzene aerogel leading to SiCN aerogel was studied. The pre-ceramic samples were obtained by crosslinking a commercially available polysilazane with divinylbenzene in a highly diluted solution. Wet gels were supercritically dried using CO2to get the pre-ceramic aerogel. The weight change during pyrolysis in flowing argon was studied by thermogravimetric analysis (in-situ measurements) and by measuring the weight change on samples pyrolyzed in a tubular furnace after cooling down to room temperature (ex-situ measurements). The structural transformation was followed by infrared spectroscopy while the microstructural changes were studied by nitrogen adsorption analysis. Results point out that samples pyrolyzed at intermediate temperature, i.e., around 600–800 °C, react with the laboratory atmosphere forming Sisingle bondO bonds and Sisingle bondOH moieties. This out-of-furnace oxidation leads to an uncontrolled increase of the oxygen content of the pyrolyzed ceramics and eventually reduces the microporosity of the samples and its stability.