Crack-resistant Al2O3–SiO2 glasses

Abstract

Obtaining “hard” and “crack-resistant” glasses have always been of great important in glass science and glass technology. However, in most commercial glasses both properties are not compatible. In this work, colorless and transparent xAl2O3–(100–x)SiO2 glasses (30 ≤ x ≤ 60) were fabricated by the aerodynamic levitation technique. The elastic moduli and Vickers hardness monotonically increased with an increase in the atomic packing density as the Al2O3 content increased. Although a higher atomic packing density generally enhances crack formation in conventional oxide glasses, the indentation cracking resistance increased by approximately seven times with an increase in atomic packing density in binary Al2O3–SiO2 glasses. In particular, the composition of 60Al2O3•40SiO2 glass, which is identical to that of mullite, has extraordinary high cracking resistance with high elastic moduli and Vickers hardness. The results indicate that there exist aluminosilicate compositions that can produce hard and damage-tolerant glasses.

Competing Indentation Deformation Mechanisms in Glass Using Different Strengthening Methods

“…Caution should be used when trying to access free volume difference by comparing the density, number density, or packing fraction across different compositions since the reference state can depend on composition. Moreover, oxide glasses can show different intrinsic toughening mechanisms via shear rather than by densification (Rosales-Sosa et al, 2016), which is worth more attention. According to previous studies (Rouxel, 2007;Shi et al, 2014), the ability to shear is associated with the opposite glass properties, such as LFV, high packing density, and high Poisson's ratio.…”

Breaking the Limit of Micro‐Ductility in Oxide Glasses

“…2019, 6,1901281 high resistance to crack initiation upon contact loading, [15] presumably due to their high fracture surface energy. Sci.…”

Additive Effects of Rare-Earth Ions in Sodium Aluminoborate Glasses Using <sup>23</sup>Na and <sup>27</sup>Al Magic Angle Spinning Nuclear Magnetic Resonance

“…In such oxide glasses, three kinds of Al coordination exist: 4-coordinated [4] Al, 5-coordinated [5] Al, and 6-coordinated [6] Al, which can all be quantitatively measured by magic angle spinning nuclear magnetic resonance (MAS NMR) [3] [4]. Using structural analysis of aluminate glasses using MAS NMR, it has been clarified that their physical properties, such as fictive temperature, microhardness, elastic modulus, and refractive index, are closely related to their Al coordination [5] [6] [7] [8]. Therefore, it is important to control Al coordination in oxide glasses for adjustments of those physical properties.…”