Chemical effects on subcritical fracture in silica from molecular dynamics simulations
Journal Article
·
· Journal of Geophysical Research. Solid Earth
- Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Geochemistry Dept.
- Sandia National Lab. (SNL-CA), Livermore, CA (United States). Mechanics of Materials Dept.
Fracture toughness of silicates is reduced in aqueous environments due to water-silica interactions at the crack tip. In this paper, to investigate this effect, classical molecular dynamics (MD) simulations using the bond-order based reactive force field (ReaxFF) were used to simulate silica fracture. The chemical and mechanical aspects were separated by simulating fracture in: (a) vacuum with dynamic loading, (b) an aqueous environment with dynamic loading, and (c) an aqueous environment with static subcritical mechanical loading to track silica dissolution. The addition of water to silica fracture reduced the silica fracture toughness by ~25%, a trend consistent with experimentally reported results. Analysis of Si-O bonds in the process zone and calculations of dissipation energy associated with fracture indicated that water relaxes the entire process zone, and not just the surface. Additionally, the crack tip sharpens during fracture in water and an increased number of microscopic propagation events occur. This results in earlier fracture in systems with increasing mechanical loading in aqueous conditions, despite the lack of significant silica dissolution. Finally and therefore, the threshold for Si-O bond breakage has been lowered in the presence of water and the reduction in fracture toughness is due to structural and energetic changes in the silica, rather than specific dissolution events.
- Research Organization:
- Sandia National Lab. (SNL-CA), Livermore, CA (United States); Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
- Sponsoring Organization:
- SNL Laboratory Directed Research and Development (LDRD) Program; USDOE; USDOE National Nuclear Security Administration (NNSA)
- Grant/Contract Number:
- NA0003525
- OSTI ID:
- 1474087
- Alternate ID(s):
- OSTI ID: 1480904
- Report Number(s):
- SAND--2018-10275J; 668010
- Journal Information:
- Journal of Geophysical Research. Solid Earth, Journal Name: Journal of Geophysical Research. Solid Earth Journal Issue: 11 Vol. 123; ISSN 2169-9313
- Publisher:
- American Geophysical UnionCopyright Statement
- Country of Publication:
- United States
- Language:
- English
The Role of Chemistry in Fracture Pattern Development and Opportunities to Advance Interpretations of Geological Materials
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journal | July 2019 |
The Role of Chemistry in Fracture Pattern Development and Opportunities to Advance Interpretations of Geological Materials
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text | January 2019 |
Effect of Domain Size, Boundary, and Loading Conditions on Mechanical Properties of Amorphous Silica: A Reactive Molecular Dynamics Study
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journal | December 2019 |
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OSTI ID:20020619