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Type: Artigo de periódico
Title: Glasses In The Si{single Bond}o{single Bond}c{single Bond}n System Produced By Pyrolysis Of Polycyclic Silazane/siloxane Networks
Author: Schiavon M.A.
Ciuffi K.J.
Yoshida I.V.P.
Abstract: In this work, polycyclic silazane/siloxane networks bearing Si{single bond}O and Si{single bond}N bonds were synthesized, via hydrosilylation reaction, from cyclotrisilazane, [CH2{double bond, long}CH(CH3)SiNH]3, and cyclotetrasiloxane, [CH3(H)SiO]4, with different Si{single bond}H:Si{single bond}vinyl molar ratios. The resulting polymers were pyrolyzed up to 1000 °C, in N2 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 °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{single bond}N, Si{single bond}O, and Si{single bond}C bonds in FTIR. The XRD patterns of the products obtained at 1500 °C displayed diffraction peaks characteristic of β-SiC and a broad halo centered at 22° (2θ), due to the amorphous silica phase. β-SiC diffraction peaks in the XRD patterns were more intense for the precursor richer in polysiloxane units, although absorptions of Si{single bond}N, Si{single bond}C, and Si{single bond}O bonds were also observed in the FTIR spectra. Thus, the final materials were characterized as SiC/SiOCN composites in nano/amorphous phases. © 2007 Elsevier B.V. All rights reserved.
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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