Abstract
The dynamic indentation behaviors of monolithic silica nanofoams of various porosities are investigated. When the pore size is on the nm scale, as the porosity increases, despite the decrease in mass density, the resistance offered by silica nanofoam to dynamic indentation is maintained at a high level, higher than the resistance of solid silica or regular porous silica. This phenomenon is related to the fast collapse of nanocells, which produces a locally hardened region and significantly increases the volume of material involved in impact energy dissipation.
Highlights
The dynamic indentation behaviors of monolithic silica nanofoams of various porosities are investigated
We examined the porosity effect on impact indentation resistance of silica nanofoam samples, with the average pore size being kept at ~80 nm
Silica nanofoam monoliths were prepared by a sol-gel approach[17], and the porous configurations were further adjusted by the subcritical calcination (SCC) technique[36]
Summary
The dynamic indentation behaviors of monolithic silica nanofoams of various porosities are investigated. When the pore size is on the nm scale, as the porosity increases, despite the decrease in mass density, the resistance offered by silica nanofoam to dynamic indentation is maintained at a high level, higher than the resistance of solid silica or regular porous silica This phenomenon is related to the fast collapse of nanocells, which produces a locally hardened region and significantly increases the volume of material involved in impact energy dissipation. In our previous experiment on silica nanofoams[32], with a similar porosity and a similar incident stress wave, the transmitted stress wave pressure and energy were much reduced if the nanocell size was smaller than ~200 nm This finding opens a door to the development of advanced EAD materials. The study was conducted on nanofoam samples with similar porosity ~60%36, 37, so as to focus on the pore size effect
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