Stress Corrosion Cracking in Amorphous Phase Separated Oxide Glasses: A Holistic Review of Their Structures, Physical, Mechanical and Fracture Properties

Abstract

Stress corrosion cracking is a well-known phenomenon in oxide glasses. However, how amorphous phase separation (APS) alters stress corrosion cracking, and the overall mechanical response of an oxide glass is less known in literature. APS is a dominant feature concerning many multicomponent systems, particularly the ternary sodium borosilicate (SBN) glass systems. Its three constituent oxides have significant industrial relevance, as they are the principal components of many industrial oxide glasses. Simulations and experimental studies demonstrate the existence of a two-phase metastable miscibility gap. Furthermore, theory suggests the possibility of three-phase APS in these oxide glasses. Literature already details the mechanisms of phase separation and characterizes SBN microstructures. Realizing that glasses are structurally sensitive materials opens a number of other questions concerning how the mesoscopic APS affects the continuum behavior of glasses, including dynamic fracture and stress corrosion cracking. This paper reviews current literature and provides a synthetic viewpoint on how APS structures of oxide glasses alter physical, mechanical, dynamic fracture, and stress corrosion cracking properties.

Residual stress versus microstructural effects on the strength and toughness of phase‐separated PbO–B2O3–Al2O3 glasses

“…After each test, the samples were immediately observed by OM (Nikon, Eclipse LV100N POL) to measure the notch size and find out whether a subcritical crack growth zone was present or not, that is, a region where a crack propagates even when the critical stress factor is smaller than the intrinsic fracture toughness, and it is usually intensified by environmental factors such as humidity 2 . The fracture toughness was calculated through the following equation: $$\begin{equation}{K_{Ic,{\rm{\;}}SEVNB}} = \frac{{{F_f}}}{{B\sqrt W }} \cdot \frac{{{S_1} - {S_2}}}{W} \cdot \frac{{3\sqrt \alpha }}{{2{{\left( {1 - \alpha } \right)}^{1.5}}}} \cdot {Y^{\rm{*}}},\end{equation}$$where Y* is calculated through the following equation: $$\begin{equation}{\rm{\;}}{Y^{\rm{*}}} = {\rm{\;}}1.9887 - 1.326\alpha - \frac{{\left( {3.49 - 0.68\alpha + 1.35{\alpha ^2}} \right)\alpha \left( {1 - \alpha } \right)}}{{{{(1 + \alpha )}^2}}},\end{equation}$$where K Ic,SEVNB is the fracture toughness (MPa m 1/2 ), F f is the fracture load (MN), B is the test piece width (m), W is the test piece depth (m), S 1 is the support span (m), S 2 is the loading span (m), α is the relative V‐notch depth ( c/W , where c is the average V‐notch depth [m]), and Y* is the stress intensity shape factor.…”

“…After each test, the samples were immediately observed by OM (Nikon, Eclipse LV100N POL) to measure the notch size and find out whether a subcritical crack growth zone was present or not, that is, a region where a crack propagates even when the critical stress factor is smaller than the intrinsic fracture toughness, and it is usually intensified by environmental factors such as humidity. 2 The fracture toughness was calculated through the following equation:…”

“…Inside the miscibility gap, there is a binodal region where the typical morphology of the minor phase is droplet‐like, whereas compositions in the central region of the dome, referring to spinodal decomposition, usually exhibit a snakelike interconnected nano‐ or microstructure. Explanations and in‐depth discussions about liquid immiscibility in glass‐formers can be found in several books and review papers 1–4 …”

“…Explanations and in-depth discussions about liquid immiscibility in glass-formers can be found in several books and review papers. [1][2][3][4] Glasses showing liquid-liquid phase separation (LLPS) at nanoscale could be transparent to visible light; however, when the second phase has micron-sized particles and, in this case, a widely different refractive index compared with that of the matrix (lead-rich vs. lead-poor phases), they are normally opaque or translucent because of light scattering. These glasses have found some commercial applications, such as the famous Vycor glass, porous substrates (after leaching out one phase), 2 perfume flasks, and cooking ware.…”

“…[1][2][3][4] Glasses showing liquid-liquid phase separation (LLPS) at nanoscale could be transparent to visible light; however, when the second phase has micron-sized particles and, in this case, a widely different refractive index compared with that of the matrix (lead-rich vs. lead-poor phases), they are normally opaque or translucent because of light scattering. These glasses have found some commercial applications, such as the famous Vycor glass, porous substrates (after leaching out one phase), 2 perfume flasks, and cooking ware. 5 Interestingly, some LLPS glasses show improved mechanical properties, which is of enormous interest in the glass field, and in some cases, they might even be transparent.…”