Slow fracture model based on strained silicate structures
- 15 November 1984
- journal article
- Published by AIP Publishing in Journal of Applied Physics
- Vol. 56 (10) , 2686-2693
- https://doi.org/10.1063/1.333789
Abstract
Slow crack growth data, molecular-orbital calculations, and vibrational spectroscopy results are used to develop an atomistic model for environmentally controlled fracture of silica glass. The model is based on chemically active bond defects generated by the strain field of the crack tip. Molecular-orbital results suggest that bond angle deformations are most effective in increasing the chemical activity of the Si–O–Si bond. Vibrational spectra identify silica polymorphs containing highly strained bonding configurations. A comparison of strained bond reactivity with crack growth results shows that strained silica polymorphs can be used to model the crack tip chemical reactions controlling slow fracture. Based on model complexes, a two-dimensional fracture model involving kink site nucleation and motion is developed. The model shows that the stress intensity dependence of the crack growth rate is controlled by the energy required to form chemically active defects in the silica structure. The absolute rate of fracture depends on the combined rates of active bond formation and chemical attack at strain induced defects. Crack growth data suggest that for silica, strain activation occurs prior to the adsorption of environmental chemicals.This publication has 14 references indexed in Scilit:
- A Molecular Mechanism for Stress Corrosion in Vitreous SilicaJournal of the American Ceramic Society, 1983
- Raman investigation of optical fibers under high tensile stressJournal of Applied Physics, 1981
- Ab initio calculated geometries and charge distributions for H4SiO4 and H6Si2O7 compared with experimental values for silicates and siloxanesPhysics and Chemistry of Minerals, 1980
- Determination of physisorbed and chemisorbed waters on silica gel and porous silica glass by means of desorption isotherms of water vaporJournal of Colloid and Interface Science, 1980
- Polymerization of silicate and aluminate tetrahedra in glasses, melts, and aqueous solutions—I. Electronic structure of H6Si2O7, H6AlSiO71−, and H6Al2O72−Geochimica et Cosmochimica Acta, 1980
- Infrared studies of reactions on oxide surfaces. 7. Mechanism of the adsorption of water and ammonia on dehydroxylated silicaThe Journal of Physical Chemistry, 1976
- Infrared studies of reactions on oxide surfaces. 6. Active sites on dehydroxylated silica for the chemisorption of ammonia and waterThe Journal of Physical Chemistry, 1976
- Infrared studies of reactions on oxide surfaces. 5. Lewis acid sites on dehydroxylated silicaThe Journal of Physical Chemistry, 1976
- Über Siliciumchalkogenide. VI. Zur Kenntnis der faserigen Siliciumdioxyd‐ModifikationZeitschrift für anorganische und allgemeine Chemie, 1954
- The Fatigue of Glass Under StressNature, 1944