Abstract
Stable crack growth was measured for nominal dry and water-bearing (6 wt%) soda-lime silicate glasses in double cantilever beam geometry and combined with DMA studies on the effects of dissolved water on internal friction and glass transition, respectively. In vacuum, a decreased slope of logarithmic crack growth velocity versus stress intensity factor is evident for the hydrous glass in line with an increase of beta-relaxation intensity indicating more energy dissipation during fracture. Further, inert crack growth in hydrous glass is found to be divided into sections of different slope, which indicates different water related crack propagation mechanism. In ambient air, a largely extended region II is observed for the hydrous glass, which indicates that crack growth is more sensitive to ambient water.
Highlights
Glass strength and fatigue are controlled by the presence and propagation of surface microcracks (Ciccotti, 2009; Wiederhorn et al, 2013a)
The present paper focuses on stable crack growth in ambient air and vacuum as well as on internal friction in these glasses
Crack propagation in nominal dry and hydrous microscope slide glasses containing 6 wt% water was studied in double cantilever beam geometry and was backed up with dynamic mechanical analysis and DTA
Summary
Glass strength and fatigue are controlled by the presence and propagation of surface microcracks (Ciccotti, 2009; Wiederhorn et al, 2013a). More recent studies indicate that crack propagation is affected by other phenomena and that a simple ≡ Si-O-Si ≡ + H2O reaction (Michalske and Freiman, 1982) is unlikely to be the stress corrosion reaction (Ito and Tomozawa, 1981; Tomozawa, 2007; Ciccotti, 2009; Wiederhorn et al, 2013c). In contrast to Michalske and Freiman (1982) it was found that compressive instead of tensile stress promote glass dissolution at the crack tip (Ito and Tomozawa, 1981). Sodium can be enriched at the fractured glass surface (Langford et al, 1991; Celarie et al, 2007), dissolve into the narrow water film at the crack tip (Wiederhorn, 1967) and cause ion exchange related swelling and compressive stress (Lanford et al, 1979). In fused silica, swelling at the crack tip was found and attributed to stress-induced water diffusion into the glass surface (Tomozawa, 1996; Fett et al, 2005; Wiederhorn et al, 2013a) as it was previously
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