Understanding the response of aluminosilicate and aluminoborate glasses to sharp contact loading using molecular dynamics simulation

Abstract

Experimental studies have shown that glass systems with high boron content exhibit superior crack resistance under sharp contact loading. However, the underlying mechanism is still not fully understood. In this context, we carried out classical molecular dynamics simulations on sodium aluminosilicate and sodium aluminoborate systems to investigate the effect of boron on the response of glass to nanoindentation. A rigid V-shaped indenter is used to indent the glass sample with a fixed loading rate, during which the indenter interacts with the glass via a repulsive force field. The indenter angle and tip radius are varied to study the effect of indenter sharpness, as what has been done in experiments. These simulated nanoindentation tests reveal how the stress/strain field and the glass structure evolve with deformation underneath the indenter. It was found that a large number of boron atoms in the plastic zone change from three- to fourfold coordination during the loading process, and most of them revert back to the threefold coordination state during the unloading process. Our study shows that this “reversible” boron coordination change plays a critical role in increasing the damage resistance of glass.

Lateral‐pushing induced surface lift‐up during nanoindentation of silicate glass

“…Nevertheless, as stated by one recent study, 34 it remains challenging to accurately determine the amplitude of the blister field during the indentation process. Moreover, recent developments [35][36][37] using molecular dynamic (MD) simulations of indentation provide convincing structural evidence from the atomic scale, while the better volume quantification from experiments is crucial for further developments in MD simulations. Mechanical strain is long-range compared to stress in the indentation experiment of silicate glasses.…”

Toward revealing atomic deformation mechanics in lithium disilicate and β‐quartz containing glass‐ceramics

“…The differential deformation of each phase is further revealed in the corresponding atomic shear—strain‐colored deformation map as shown in Figure 2A‐3 and B‐3. Unlike the typical hemispherical shape of plastic zone for glasses under indentation loading, 22,26 both glass‐ceramics samples exhibit very irregular plastic zone shape with multiple dendritic‐like shear bands emanating from the indenter and also some less‐shear‐susceptible “islands” (nanocrystals) sitting firmly against surrounding shear flow. The results suggest that the presence of nanocrystals significantly limits free space for continuous plastic zone expansion upon indentation loading in glass‐ceramics.…”

Molecular dynamics study on the viscosity of glass‐forming systems near and below the glass transition temperature

“…29,30 The physics of resin under pressure is similar to the seepage pr lar approaches have been used also to mod into a mold containing fiber mats. 23,[31][32][33][34][35][36][37][38] T in these cases to determine the resin flow ing times corresponding to different infilt Preceramic polycarbosilane polymers as precursors to make ceramic fibers 10,3 trix. [7][8][9]40,41 The chemical and volume ch pany ceramization of the polymer during documented in several studies.…”

“…Classical MD simulations were carried out in LAMMPS package [36][37][38] for four glass-forming systems: model metallic glass, silica, Cu 45.5 Zr 45.5 Al 9 and silicon, which were modeled using binary Lennard Jones potential parameterized by Kob and Andersen (KA), 39 the Beest-Kramer-Santen potential, 40 embedded atom method (EAM), 41 and the Stillinger-Webber potential, 42 respectively. For the KA system, we will use reduced units for all physical quantities unless otherwise noted, in terms of m 0 (same mass for both species), σ (the Lennard-Jones length parameter between the larger species), and ε (the Lennard-Jones energy parameter between the larger species).…”

“…29,30 The physics of resin flow into a mold under pressure is similar to the seepage problem and so similar approaches have been used also to model the flow of resin into a mold containing fiber mats. 23,[31][32][33][34][35][36][37][38] The models are used in these cases to determine the resin flow front and mold filling times corresponding to different infiltration conditions.…”