The effect of water penetration on crack growth in silica glass

Wiederhorn, Sheldon M.; Fett, T.; Rizzi, G.; Hoffmann, Michael J.; Guin, Jean‐Pierre

doi:10.1016/j.engfracmech.2012.04.026

Cited by 34 publications

(40 citation statements)

References 23 publications

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“…This explains the apparently anomalous results reported for silica (Suratwala and Steele, 2003), and silica aerogels (Despetis et al, 2004), where the measured crack propagation speed decreases with increasing temperature. Wiederhorn et al (2013b) have developed a formalism that enables the direct calculation of the shielding stresses as a function of both applied stresses and temperature. The estimated activation energies for region I are 114 ± 8 kJ mol −1 for the soda-lime silicate glass and 156 ± 5 kJ mol −1 for silica glass; for region III the activation energy for the soda-lime silicate is 314 ± 9 kJ mol −1 .…”

Section: Application To Experimental Datamentioning

confidence: 99%

Parametrization in Models of Subcritical Glass Fracture: Activation Offset and Concerted Activation

et al. 2017

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There are two established but fundamentally different empirical approaches to parametrize the rate of subcritical fracture in brittle materials. While both are relying on a thermally activated reaction of bond rupture, the difference lies in the way as to how the externally applied stresses affect the local energy landscape. In the consideration of inorganic glasses, the strain energy is typically taken as an offset on the activation barrier. As an alternative interpretation, the system's volumetric strain energy is added to its thermal energy. Such an interpretation is consistent with the democratic fiber bundle model. Here, we test this approach of concerted activation against macroscopic data of bond cleavage activation energy, and also against ab initio quantum chemical simulation of the energy barrier for cracking in silica. The fact that both models are able to reproduce experimental observation to a remarkable degree highlights the importance of a holistic consideration toward non-empirical understanding.

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Section: Application To Experimental Datamentioning

confidence: 99%

Parametrization in Models of Subcritical Glass Fracture: Activation Offset and Concerted Activation

et al. 2017

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“…Stress-corrosion is classically interpreted as a thermally activated and stress enhanced hydrolysis reaction where the main reactant is provided by environmental water molecules [11]. Water molecules were also proved to diffuse into a few nanometer layer below crack surfaces [12], where they may possibly alter the glass structure by inducing local damage or flow [13,14], or even by inducing compressive stresses and thus a partial shielding of the crack tip stresses [15]. Water molecules coming from the environment could thus play an important role in the local perturbation of the crack propagation direction and thus in the development of the fracture surface roughness.…”

Section: Introductionmentioning

confidence: 99%

Roughness of oxide glass subcritical fracture surfaces

Pallares

Lechenault²,

George

et al. 2017

J Am Ceram Soc

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An original setup combining a very stable loading stage, an atomic force microscope and an environmental chamber, allows to obtain very stable sub-critical fracture propagation in oxide glasses under controlled environment, and subsequently to finely characterize the nanometric roughness properties of the crack surfaces. The analysis of the surface roughness is conducted both in terms of the classical root mean square roughness to compare with the literature, and in terms of more physically adequate indicators related to the self-affine nature of the fracture surfaces. Due to the comparable nanometric scale of the surface roughness, the AFM tip size and the instrumental noise, a special care is devoted to the statistical evaluation of the metrologic properties. The 2 roughness amplitude of several oxide glasses was shown to decrease as a function of the stress intensity factor, to be quite insensitive to the relative humidity and to increase with the degree of heterogeneity of the glass. The results are discussed in terms of several modeling arguments concerning the coupling between crack propagation, material's heterogeneity, crack tip plastic deformation and water diffusion at the crack tip. A synthetic new model is presented combining the predictions of a model by Wiederhorn et al. [1] on the effect of the material's heterogeneity on the crack tip stresses with the self-affine nature of the fracture surfaces.

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“…For glasses that do not contain mobile alkali ions, such as silica glasses, swelling due to molecular water diffusion was proposed . Water diffusion and subsequent swelling were recently shown to produce compressive stresses up to ~35 MPa for silica glasses soaked in liquid water at 90°C for up to 672 h. It will be shown later that GPa range compressive stresses, orders of magnitude higher than those produced by swelling, are required to explain the apparent strengthening.…”

Section: Introductionmentioning

confidence: 99%

Modeling Slow Crack Growth Behavior of Glass Strengthened by a Subcritical Tensile Stress Using Surface Stress Relaxation

et al. 2015

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Glasses exhibit slow crack growth under stress intensities below the fracture toughness in the presence of water vapor or liquid water. It has been observed by several authors that when an oxide glass with a large crack is held under a subcritical stress intensity (where no slow crack growth occurs) in room‐temperature water vapor or liquid water, upon reloading to a higher stress intensity, a finite restart time is observed prior to measurable crack extension. This phenomenon of apparent strengthening, or crack arrest, has been attributed to concepts such as corrosive dissolution of the crack tip, crack tip blunting, or water diffusion, and subsequent swelling of the material around the crack tip. Recently, a newly observed surface stress relaxation process that is aided by molecular water diffusion was used to improve the mechanical strength of glass fibers and to explain the subsurface compressive stress peak observed in ion‐exchange strengthened glasses. The same process is employed here to explain these delayed slow crack growth data. A simple mathematical model has been developed utilizing water‐assisted surface stress relaxation and fracture mechanics. Predictions of restart times using the model agreed well with published experimental data, indicating that surface stress relaxation is responsible for the anomalous delayed slow crack growth behavior.

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The effect of water penetration on crack growth in silica glass

Cited by 34 publications

References 23 publications

Parametrization in Models of Subcritical Glass Fracture: Activation Offset and Concerted Activation

Parametrization in Models of Subcritical Glass Fracture: Activation Offset and Concerted Activation

Roughness of oxide glass subcritical fracture surfaces

Modeling Slow Crack Growth Behavior of Glass Strengthened by a Subcritical Tensile Stress Using Surface Stress Relaxation

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