(Thermo)Mechanical Properties of SiOC-Based Glasses and Glass CeramicsThursday (29.09.2016) 16:15 - 16:30 Part of:
In the present study, dense monolithic SiOC glasses and glass ceramics with different compositions (i.e., various carbon contents) and different microstructures (i.e., single-phasic and phase-separated) were prepared and structurally characterized.
The high-temperature creep behavior of the investigated glasses was assessed and revealed two features of the studied SiOC samples: (i) a viscous contribution to the creep, coming from the silica rich network, and (ii) an elastic response to stress, coming from the segregated carbon phase present in the samples; this is in agreement to the previously proposed nano-heterogeneous network topology of SiOC glasses.
Furthermore, two distinct effects of the carbon phase on the HT creep behavior of SiOC were identified and will be discussed: the effect of the carbon present within the SiOC network (the "carbidic" carbon), which induces a significant increase of the viscosity and a strong decrease of the activation energy for creep as compared to vitreous silica; and the influence of the segregated carbon phase, which has been shown to affect the viscosity and the activation energy of creep and dominates the creep behavior in phase-separated silicon oxycarbides.
In addition to the effect of the phase composition and microstructure on the high-temperature creep behavior of SiOC glasses and glass ceramics, studies related to their elastic properties (Young's modulus, Poisson ratio), hardness as well as thermal conductivity will be presented and discussed.