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نیک فایل

مرجع دانلود فایل ,تحقیق , پروژه , پایان نامه , فایل فلش گوشی

Effects of Zr on the precursor architecture and high-temperature nanostructure evolution of SiOC polymer-derived ceramics

اختصاصی از نیک فایل Effects of Zr on the precursor architecture and high-temperature nanostructure evolution of SiOC polymer-derived ceramics دانلود با لینک مستقیم و پر سرعت .

Effects of Zr on the precursor architecture and high-temperature nanostructure evolution of SiOC polymer-derived ceramics

 

ژورنال: Journal of the European Ceramic Society

سال: October 2015

قیمت اصلی: 35.95$

 

Abstract

SiOC and SiZrOC ceramics were obtained starting from the hydrosilane system without and with zirconium n-propoxide (Zr(OnPr)4) by sol–gel route. The precursor architectures indicated that the presence of Sisingle bondH bonds leads to a different cross-linking mechanism of SiZrOC precursor, where the Sisingle bondH bonds were involved in the formation of Sisingle bondOsingle bondZr bonds. The presence of Zr caused a lower content of sp3 carbon in SiZrOC ceramics. At above 1400 °C, the sp3-C/Si ratio in both ceramics increased due to carbothermal reduction, especially rapidly for SiOC ceramics, suggesting the carbothermal reduction in SiZrOC ceramics has been strongly suppressed with the presence of ZrO2. Raman spectroscopy showed the graphitization degree of free carbon increased with temperature in both ceramics, but was always lower in SiZrOC ceramics. The SiZrOC ceramics has been found to exhibit remarkably high temperature stability with respect to carbothermal decomposition up to 1600 °C in comparison with the SiOC ceramics.

 

Keywords

  • SiZrOC polymer-derived ceramics
  • Precursor architecture
  • Nanostructure evolution;
  • Free carbon

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Effects of Zr on the precursor architecture and high-temperature nanostructure evolution of SiOC polymer-derived ceramics
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