Environmentally Enhanced Fracture of Glass: A Historical Perspective

Abstract

In this paper, we review the phenomenon of delayed failure, a life‐limiting process for glasses that are subjected to tensile stresses. With the development of crack‐weakening theories (Ingles and Griffith) and the observation that surface damage enhances delayed failure, the scientific community recognized that delayed failure in glass is caused by the growth of cracks that are subjected to tensile stresses. Fracture mechanics techniques were used to quantify crack growth rates in terms of applied stress, temperature, and the chemical environments that cause subcritical crack growth. We review the theories that have been developed to rationalize subcritical crack growth data, including theories based on plastic deformation at the crack tip, chemical adsorption of the reacting species, and direct chemical reaction of the environment with the strained bonds at the crack tip. The latter theory seems to be most consistent with the finding that water reacts directly with the strained Si–O bond because of the ability of water to donate both electrons and protons to the strained bond. Other chemicals having this characteristic also cause subcritical crack growth. Finally, we review the quantum mechanical calculations that have been used to quantify the chemical reactions involved in subcritical crack growth.

Strategies to Avert Electrochemical Shock and Their Demonstration in Spinels

“…For example, cyclic subcritical stresses can lead to fatigue failure, chemically-assisted fracture mechanisms such as stress-corrosion cracking, or both. [42][43][44][45] These additional mechanisms remain to be explored. Further, the increased specific surface area of finer particles may accelerate undesirable side reactions, such as electrolyte decomposition.…”

Performance of Dental Ceramics: Challenges for Improvements

“…The mechanism responsible for this loss of strength in dental ceramics is the combined effect of stress corrosion by water molecules at the crack tip and mechanical degradation of the polycrystalline dental ceramics (Freiman et al, 2009;Salazar Marocho et al, 2010). Of the non-zirconia core materials, glassinfiltrated alumina (InCeram Alumina) is the most susceptible, followed by lithium disilicate (IPS Empress 2) (Gonzaga et al, 2009).…”

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

“…The subcritical crack growth and its dependence on environmental conditions have profound consequences for the glass industry and the suitability of glass as a structural material. Here, parametric knowledge is needed not only for the focused development of new material compositions and toughening procedures but also for enabling better time-to-failure estimations (Freiman et al, 2009). Beyond materials development, this need encompasses other related areas such as the understanding of geophysical fracture processes (Atkinson, 1982;Brantut et al, 2013;Zhang and Zhao, 2014).…”