Molecular dynamics study on nano‐particles reinforced oxide glass

Abstract

Energy release rate and fracture toughness of amorphous aluminum nanoparticles reinforced soda‐lime silica glass (SLSG) were measured by performing fracture simulations of a single‐notched specimen via molecular dynamics simulations. The simulation procedure was first applied to conventional oxide glasses and the accuracy was verified with comparing to experimental data. According to the fracture simulations on three models of SLSG/‐Al2O3 composite, it was found that the crack propagation in the composites is prevented through following remarkable phenomena; one is that a‐Al2O3 nanoparticles increase fracture surface area by disturbing crack propagation. The other is that the deformation of a‐Al2O3 nanoparticle dissipates energy through cracking. Moreover, one of the models shows us that the crack cannot propagate if the initial notch is generated inside a‐Al2O3 nanoparticle. Such strengthening is partly due to the fact that the strength of the interface between nanoparticle and SLSG matrix is comparable to that of SLSG matrix, implying that their interface does not reduce crack resistance of the oxide glass.

3D microstructure and crack pathways of toughened CaO–Al2O3–SiO2 glass by precipitation of hexagonal CaAl2Si2O8 crystal

“…The boundary atoms were fixed in the other two directions. The fracture simulation is described in further detail in Ref …”

“…The fracture simulation is described in further detail in Ref. 35 Figure 5 shows examples of the SEM images obtained by FIB-SEM. In these figures, the dark areas correspond to the hexagonal CaAl 2 Si 2 O 8 crystals, whereas the bright spots observed in the center of the crystals are metallic molybdenum particles.…”

Molecular dynamics investigation of the fracture mechanism of a glass‐ceramic containing cleavable crystals

“…E y is 80.7 GPa estimated from the slope of the S‐S curve of the larger composite model (see Figure ), and Poisson's ratio is assumed to be 0.23. Detail of the estimation procedure can be found in our previous work . The S‐S curve of Type‐C apparently demonstrates brittle fracture because the stress sharply drops beyond the stress peak as the strain increases.…”

“…To initiate an initial crack propagation by uniaxial loading, a constant velocity of 0.1 m/s was imparted to the atoms located within 5 Å from the both sides of the simulation cell. The velocity is vary fast in comparison with experimentally available deformation speed; however, our previous study, which has examined fracture of soda‐lime silica glass, revealed that the simulation procedure with the same velocity can reproduce experimental fracture toughness within reasonable accuracy . The MD unit cell has sufficient spaces in X and Z directions for avoiding interaction among atoms in the both edges, and periodic boundary condition was considered in all directions to calculate electrostatic interaction by the Ewald method.…”

“…For example, Galiolini et al have devoted to understand adhesion between an oxide glass and Al 2 O 3 and Si 3 N 4 , Sun and Du have recently investigated an interlayer between an aluminosilicate glass and a MgAl 2 O 4 spinel crystal, and Lusvardi et al have tried to evaluate possibility of crystallization in some oxide glasses. Furthermore, fracture patterns in amorphous aluminum nano‐particles embedded soda‐lime silica glass have been investigated . Thus we employ MD simulations in this study to investigate crack propagation and anisotropy of microscale deformation in the SiO 2 –Al 2 O 3 –CaO glass‐ceramics, in which h‐CASs are precipitated.…”