Enhancement in nanohardness of soda-lime-silica glass

For a thin commercial soda-lime-silica glass cover slip a significant increase in nanohardness (e.g. up to 74%) occurred with variations in the loading rate (10-20,000 μN·s^− 1) along with presence of serrations in load-depth plots and deformation band formation inside the nanoindentation cavity. These results are explained in terms of shear stress acting at positions of structural weakness close to the tip of the nanoindenter and the time scale of interaction between the nanoindenter and the local microstructure of the glass.