High temperature stability of sol-gel-derived SiOC glasses

The high temperature stability of sol-gel-derived SiOC glasses has been inv estigated in order to understand the role played by the presence of a free- carbon phase in the amorphous oxycarbide network. Therefore, pure and exces s free-carbon containing SiOC glasses have been prepared from hybrid gels a nd used for the high temperature stability experiments. Moreover, the possi ble effects of the sample size with respect to local kinetics and thermodyn amics and of the testing environment have also been investigated. Results s how that all these parameters play a crucial role in defining the high temp erature behavior of SiOC glasses.