Oxidation behavior of Si-Nb-C-O ceramics prepared by the pyrolysis of methyltriethoxysilane based organic-inorganic hybrid gel
Oxidation behavior of Si-Nb-C-O ceramics prepared by the pyrolysis of methyltriethoxysilane based organic-inorganic hybrid gel
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DOI：
10.1007/s10971-005-1258-8
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发表时间：
2005-04-01
影响因子：
2.5
通讯作者：
Tanabe, Y
中科院分区：
文献类型：
--
作者：
Fukushima, M;Yasuda, E;Tanabe, Y
研究了过渡金属聚甲基倍半硅氧烷杂化处理制备的Si-Nb-C-O陶瓷的氧化结构特征。前驱体杂化凝胶的热解温度对所得陶瓷的氧化行为有很大影响。600℃热解的杂化凝胶快速氧化，1000℃热解的杂化凝胶表现出较高的抗氧化性。在600℃热解的杂化产物中，氧化后形成了新的Si-O-Nb氧桥杂金属键，FT-IR光谱证实了这一点。X射线光电子能谱(XPS)分析表明，在1000℃的高温下，杂化材料的氧化表面形成了二氧化硅和碳氧化物保护层。拉曼光谱显示了较大的发光背景，氧化前的G和D带。氧化后，发光背景消失，G带比非氧化产物更加对称。这有力地表明了陶瓷中自由基和相关的不稳定碳物种的主要氧化。
The oxidative structural characterization of Si-Nb-C-O ceramic prepared by the heat-treatment of transition metal containing polymethylsilsesquioxane hybrid was investigated. The heating temperature for the pyrolysis of precursor hybrid gels strongly affected the oxidation behavior of the resultant ceramics. The hybrid gel, pyrolyzed at 600° C was rapidly oxidized, while the hybrid gel pyrolyzed at 1000° C showed the higher resistance to oxidation. In the hybrid pyrolyzed at 600° C, new Si-O-Nb oxygen-bridged heterometal bonds were formed after oxidation, which was confirmed by FT-IR spectra. On the other hand, silica and oxycarbide protective layer was formed on the oxidized surface of the hybrid heated at 1000° C, as suggested by X-ray photoelectron spectroscopy (XPS). Raman spectra showed a large luminescence background, G and D bands before oxidation. After oxidation, however, the luminescence background disappeared and G band was more symmetric than that of non-oxidative product. This strongly suggested the predominant oxidation of radical and related unstable carbon species in the ceramics.