Toughening of soda-lime-silica glass by nanoscale phase separation: Molecular dynamics study

Abstract

The low fracture toughness of oxide glasses is a key limitation for many of their applications. Inducing and controlling nanoscale phase separation in oxide glasses has been proposed as a potential toughening strategy, as, unlike many alternative extrinsic toughening approaches, it allows to retain the optical transparency. Using molecular dynamics simulations, we here investigate the toughening mechanism in soda-lime-silica glasses with embedded glassy nanoscale silica droplets. This system is chosen as a model for the experimental structure of phase-separated soda-lime-silica glass, which is attractive considering its existing commercial use and the ease of inducing phase separation. We calculate the fracture toughness of glass structures containing nanodroplets of varying sizes and with different precrack positions, revealing that the glassy silica droplets toughen the material. The simulations show that crack propagation is impeded by crack arrest, crack deflection and diversion, and stress field alteration, ultimately increasing the fracture toughness. Our findings thus shed light on the toughening mechanism due to phase separation, with important implications for the experimental design of oxide glasses with controlled nanoscale phase separation.

Mechanisms of microstructural deformation governing Vickers hardness in phase‐separated calcium aluminosilicate glasses

“…2 Phase separation has been proposed as a route for producing low-brittleness glasses by increasing the fracture toughness via crack deflection. [3][4][5][6] Additionally, through the fine control of the droplet size and morphology, optically clear phase-separated glasses can be synthesized. 7 Although the possible increase in fracture toughness from phase separation has generated much interest as a means to reduce brittleness, much less attention has been given to how phase separation may impact hardness.…”

“…In their computational study on phase-separated soda lime silicate glasses, Christensen et al differentiated between the composition of the glass before and after the insertion of a silica-rich inclusion and also tested an additional homogeneous glass that had nearly the same average composition as the phase-separated glass. 4 This approach allows the effects of microstructure and composition to be decoupled. Unfortunately, this approach is not always experimentally feasible.…”

Residual stress versus microstructural effects on the strength and toughness of phase‐separated PbO–B2O3–Al2O3 glasses

“…This discussion is not new, and the literature brings several studies on the mechanical properties of oxide glasses showing LLPS, such as the Li 2 O–B 2 O 3 –SiO 2 , 6 Na 2 O–B 2 O 3 –SiO 2 , 6–8 Na 2 O–CaO–SiO 2 , 9 B 2 O 3 –SiO 2 , 9,10 PbO–B 2 O 3 , 11–13 K 2 O–Li 2 O–SiO 2 , 14 and B 2 O 3 –SiO 2 –Al 2 O 3 –P 2 O 5 15 glasses. Recently, these studies have resurfaced in the field of computer simulations to predict the mechanical properties of phase‐separated glasses 16,17 . Some selected previous studies addressing the mechanical properties of LLPS systems are briefly summarized as follows.…”

“…Recently, these studies have resurfaced in the field of computer simulations to predict the mechanical properties of phase-separated glasses. 16,17 Some selected previous studies addressing the mechanical properties of LLPS systems are briefly summarized as follows.…”

Impact Of Local Structural Characteristics On Glass-formation In Metal-organic Frameworks

“…With MOFs having unit cells that can exceed 50 unique atoms (95), it is clear how models with a high computational load will be limited in simulation size. For characteristics requiring larger simulation systems, like, crack propagation in glasses (188), ion-exchange strengthening (189), and ionic conduction (190), this limitation to the size of the system makes quantum mechanical models inappropriate.…”