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Nanostructural Characterization of Silicon Oxycarbide Glasses and Glass‐Ceramics
Author(s) -
Breval Else,
Hammond Michael,
Pantano Carlo G.
Publication year - 1994
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/j.1151-2916.1994.tb04538.x
Subject(s) - materials science , cristobalite , hot pressing , crystallization , silicon carbide , crystallinity , amorphous solid , graphite , ceramic , silicon , carbon fibers , nanocrystalline silicon , carbide , chemical engineering , composite material , mineralogy , amorphous silicon , metallurgy , crystalline silicon , crystallography , composite number , chemistry , quartz , engineering
Silicon oxycarbide glasses were synthesized by the sol‐gel process using precursors such as methyl‐, propyl‐, and phenyltrimethoxysilanes. The final products contained 14–38 wt% carbon. A TEM study on the nanometer scale revealed that all of the materials were amorphous and monophasic, and that it was not possible to detect any crystalline or otherwise distinct carbon phases. Hot‐pressing the glasses led to the crystallization of graphite and silicon carbide within the amorphous matrix. X‐ray and electron diffraction showed increasing crystallinity at the higher hot‐pressing temperatures. Hot pressing at 1400°C resulted in the appearance of fine‐grained silicon carbide, whereas at the highest temperature (1650°C), graphite and both hexagonal and cubic silicon carbide were produced. Subsequent heat treatment of the hot‐pressed glasses under an argon atmosphere at 1400°C resulted in the formation of cristobalite. The glass‐ceramics produced at the highest hot‐pressing temperatures were more resistant to the crystallization of cristobalite during subsequent heat treatments.