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Type: Artigo de periódico
Title: Glasses in the Si-O-C-N system produced by pyrolysis of polycyclic silazane/siloxane networks
Author: Schiavon, MA
Ciuffi, KJ
Yoshida, IVP
Abstract: In this work, polycyclic silazane/siloxane networks bearing Si-O and Si-N bonds were synthesized, via hydrosilylation reaction, from cyclotrisilazane, [CH2=CH(CH3)SiNH](3), and cyclotetrasiloxane, [CH3(H)SiO](4), with different Si-H:Si-vinyl molar ratios. The resulting polymers were pyrolyzed up to 1000 degrees C, in N-2 atmosphere, producing SiOCN glasses. The polymer-to-ceramic transformation was studied by thermogravimetry (TG), Fourier transform infrared spectroscopy (FTIR), and chemical analysis. The 1000-1500 degrees C, high temperature structural evolution was also studied using X-ray diffraction (XRD) and FTIR. The hydrosilylation reaction produced ethylenic bridge crosslinked polymeric precursors with good thermal stability. The SiOCN glasses obtained with ceramic yields higher than 80 wt% showed spectra absorptions of Si-N, Si-O, and Si-C bonds in FTIR. The XRD patterns of the products obtained at 1500 degrees C displayed diffraction peaks characteristic of beta-SiC and a broad halo centered at 22 degrees (2 theta), due to the amorphous silica phase. beta-SiC diffraction peaks in the XRD patterns were more intense for the precursor richer in polysiloxane units, although absorptions of Si-N, Si-C, and Si-O bonds were also observed in the FTIR spectra. Thus, the final materials were characterized as SiC/SiOCN composites in nano/amorphous phases. (c) 2007 Elsevier B.V. All rights reserved.
Subject: crystallization
silicon oxynitride glasses
silicon oxycarbide glasses
polymer-derived ceramics
Country: Holanda
Editor: Elsevier Science Bv
Citation: Journal Of Non-crystalline Solids. Elsevier Science Bv, v. 353, n. 22-23, n. 2280, n. 2288, 2007.
Rights: fechado
Identifier DOI: 10.1016/j.jnoncrysol.2007.03.004
Date Issue: 2007
Appears in Collections:Unicamp - Artigos e Outros Documentos

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