Nanoindentation of Soda Lime–Silica Glass: Effect of Loading Rate

Abstract

Structural and mechanical reliability of glass for both conventional and advanced applications is determined by the rate at which it can deform and sustain externally applied static or dynamic strain at the microstructural length scale. Hence, a large number of nanoindentation experiments were conducted on a thin (∼300 μm) commercial soda lime–silica glass with a 150 nm radius Berkovich tip at a constant load of 10,000 μN as a function of variations in the loading rates in the range of 10–20,000 μN/s. The results showed that the nanohardness of the soda lime–silica glass increased by as much as 74% as the loading rate was increased from 10 to 20,000 μN/s. Further, the presence of serrations in load–depth plots and deformation band formations inside the nanoindentaion cavities were more vividly observed in the nanoindentation experiments conducted at lower loading rates rather than those conducted at higher loading rates. These results are explained in terms of shear stress acting underneath the indenter as well as the time scale of interaction between the nanoindenter and the weak links at local microstructural length scale, which owe their origin to the subtle variations in the composition of the given glass.

Contact Deformation of Alumina

“…Similar observations were also reported for glass [21][22][23][24], polycrystalline alumina [25,26,43,44], bulk metallic glasses [27][28][29], sapphire [30], GaN [31], and ZnO [32].…”

“…The occurrence of the pop-in behaviour was also reported for glass [21][22][23][24], polycrystalline alumina [25,26,43,44], bulk metallic glass [27][28][29], sapphire [30], GaN [31], and ZnO [32]. The occurrence of pop-in has often been associated with shear localization [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37].…”

“…The effect of these deformations are revealed by the occurrence of "multiple micro-pop-in" and "multiple micropop-out" events in the load-depth plots, followed by the formation of shear deformation bands and localized microcracking in and around the indentation cavity [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37] and the formation of dislocation loops in the alumina sample. The detailed mechanisms of pop-in events which occur during indentation in ceramics are far from being well understood and may be strongly sensitive to the plane bearing the nanoindentation, nanoindenter tip radius, temperature and so forth, while the microscale hardness may [38][39][40][41] or may not be [42] sensitive to strain and loading rate variation.…”

“…Recently, significant effect of loading rate on hardness of glass [21][22][23][24] and alumina [25,26,43,44] was reported. The occurrence of the pop-in behaviour was also reported for glass [21][22][23][24], polycrystalline alumina [25,26,43,44], bulk metallic glass [27][28][29], sapphire [30], GaN [31], and ZnO [32].…”

Driving force for indentation cracking in glass: composition, pressure and temperature dependence

“…(Online version in colour.) method is known to change with the applied load-a decrease of H is mostly observed with an increase of P. For a-SiO 2 , it decreases from ≈11.3 to ≈6.3 GPa as the load increases from 10 mN to 1 N [30,31], and for a standard window glass, it changes from ≈6.3 to 4.5 GPa as the load increases from 10 mN to 10 N [14,32]; this is the so-called indentation size effect (ISE) that is discussed below.…”