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Effect of Ca and B incorporation into silicon oxycarbide on its microstructure and phase composition
Author(s) -
Xie Fangtong,
GonzaloJuan Isabel,
Breitzke Hergen,
Fasel Claudia,
Trapp Maximilian,
Buntkowsky Gerd,
Kleebe HansJoachim,
Riedel Ralf,
Boccaccini Aldo R.,
Ionescu Emanuel
Publication year - 2019
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.16620
Subject(s) - silicon , depolymerization , crystallization , materials science , pyrolysis , phase (matter) , carbon fibers , microstructure , chemical engineering , ceramic , thermogravimetric analysis , polymer , chemistry , organic chemistry , polymer chemistry , composite material , composite number , optoelectronics , engineering
Abstract Ca‐ and/or B‐modified silicon oxycarbides were synthesized via pyrolysis of suitable polysilsesquioxane‐based single‐source precursors. Their polymer‐to‐ceramic transformation was investigated with thermogravimetric analysis, coupled with in situ evolved gas analysis. The prepared silicon oxycarbides were investigated with respect to their crystallization behavior, network architecture, and chemical compositions. The network connectivity in silicon oxycarbides can be affected/tuned upon using two different “tools”: (a) first, the use of network modifiers, such as Ca in our study, leads to a slight depolymerization of the network via generation of a small amount of Q 3 sites; (b) second, the modification of silicon oxycarbide with B/Ca leads to a decrease of the carbon content in the network and thus to a significant decrease of its connectivity. Using these two different effects, the network connectivity in silicon oxycarbides can be finely tuned.