Indentation cracking and deformation mechanism of sodium aluminoborosilicate glasses

Januchta, Kacper; Liu, Pengfei; Hansen, Søren Ravn; To, Theany; Smedskjær, Morten Mattrup

doi:10.1111/jace.16894

Cited by 21 publications

(14 citation statements)

References 38 publications

(146 reference statements)

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“…Hence, the enhanced crack resistance of the 4 mol% Al 2 O 3 glass cannot be attributed to densification. This observation is in agreement with a recent study on alumino borosilicate glasses by Januchta et al (2019a), who neither found a direct correlation between the fracture initiation resistance and densification. The significant changes in the fraction of boroxol and borate rings upon indentation rather indicate that those units have played a significant role during deformation.…”

Section: Discussionsupporting

confidence: 93%

“…Finally, it is worth noting that an enhanced fracture initiation load does not correspond to a higher fracture toughness, which describes the critical stress intensity factor for crack growth (Rouxel and Yoshida, 2017;Januchta et al, 2019a). Concerning the fracture toughness, it is even disadvantageous if the crack can surpass certain structural units (e.g., boroxol rings) and has to break less bonds on its way through the material (Januchta et al, 2019b).…”

Section: Discussionmentioning

confidence: 99%

“…Concerning the fracture toughness, it is even disadvantageous if the crack can surpass certain structural units (e.g., boroxol rings) and has to break less bonds on its way through the material (Januchta et al, 2019b). As the fracture toughness is directly linked to bond strength and packing density, similar to the elastic modulus, it is expected to correlate with E (Rouxel, 2017;Januchta et al, 2019a). In this manner the decrease in the elastic modulus indicates a fracture toughness reduction for the NBS2 glass with higher alumina content and after quenching.…”

Section: Discussionmentioning

confidence: 99%

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Influence of Al2O3 Addition on Structure and Mechanical Properties of Borosilicate Glasses

et al. 2020

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Alkali-borosilicate glasses are one of the most used types of glasses with a high technological importance. In order to optimize glasses for diverse applications, an understanding of the correlation between microscopic structure and macroscopic properties is of central interest in materials science. It has been found that the crack initiation in borosilicate glasses can be influenced by changes in network interconnectivity. In the NBS2 borosilicate glass system (74.0SiO 2 -20.7B 2 O 3 -4.3Na 2 O-1.0Al 2 O 3 in mol%) two subnetworks are present, i.e., a silicate and a borate network. Increasing cooling rates during processing were found to improve glasses crack resistance. Simultaneously, an increase in the network interconnectivity accompanied by an increasing capacity for densification were noticed. Their individual contribution to the mechanic response, however, remained unclear. In the present study the borosilicate glasses were systematically modified by addition of up to 4.0 mol% Al 2 O 3 . Changes in the network connectivity as well as the short-and medium-range order were characterized using Raman and NMR spectroscopy. Both the Raman and the 11 B NMR results show that four-fold-coordinated boron is converted into three-fold-coordination as the Al 2 O 3 content increases. Additionally, 27 Al NMR experiments show that aluminum is dominantly present in four-fold coordination. Aluminum-tetrahedra are thus charge balanced by sodium ions and incorporated into the silicate network. Finally, nanoindentation testing was employed to link the inherent glass structure and its network configuration to the mechanical glass response. It was found that the glass softens with increasing Al 2 O 3 content, which enhances the crack resistance of the borosilicate glass.

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Section: Discussionsupporting

confidence: 93%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Influence of Al2O3 Addition on Structure and Mechanical Properties of Borosilicate Glasses

et al. 2020

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“…Crack resistance is also depended on the bond strength (To et al, 2020), as the stronger the bonds in 9 For isotropic materials, the Bulk modulus K is related to the Young's modulus and Poisson's ratio as: the network, the more difficult to break. Januchta et al (2020) also correlate CR to the Bulk modulus 9 stating that flexible glasses can distribute the residual stress in a larger field. At this point, it should be elaborated that Hardness, which quantifies the resistance of a ceramic material to deformation and densification, is not inversely related to CR (Table 4).…”

mentioning

confidence: 79%

Exploratory Study on the Fracture Resistance of Cast Glass

Bristogianni¹,

Oikonomopoulou²,

Veer³

et al. 2021

International Journal of Structural Glass and Advanced Material

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The emerging interest in the architectural applications of cast glass components reveals a knowledge gap on the mechanical properties of cast glass. Apart from its chemical composition, cast glass is characterized by its manufacturing history and thermal profile, often inheriting a set of defects that define its properties. The role that inhomogeneities in the bulk of voluminous glass components have on the strength of the final product is also uncertain. Systematic testing is therefore necessary for the safe structural application of cast glass. Towards this direction, the presented research aims to experimentally investigate the fracture resistance of cast glass under sharp contact loading, by means of a customized splitting test using a sharp linear indenter. Cubic specimens with 50 mm sides are kiln-cast at low forming temperatures, employing a variety of silicate-based cullet and firing schedules and their inherent defects are documented. The results of the splitting tests show that the borosilicate specimens fail at the highest splitting force, followed by the soda lime float specimens, while the fused or porous specimens have a significantly lower resistance to fracture. The strength order of the various glasses, as this results from the splitting tests-is opposite to that found earlier in four-point bending tests, due to the different fracture mechanisms activated. The fracture resistance of a glass specimen is governed, first by its ability to deform around the indenter to relief the developing stresses and then by its bond strength to resist crack propagation. Thus, a good balance between glass network flexibility and high bond dissociation energy is required, explaining why the tested homogeneous borosilicate and soda lime glasses are more resistant than the modified soda lime compositions with high alkali content. In addition, the fractographic analysis indicates that the non-stress inducing flaws in the bulk have a negligible contribution to the fracture resistance of the specimens.

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“…We then employ an approach that is similar to the method for recovery of indentation volume to estimate densification contribution to overall indentation deformation. 28,29 That is, we calculate the aging-induced side length recovery (L AR ) as, 𝐿 𝐴𝑅 = 𝐿 𝑠,𝑖 − 𝐿 𝑠,𝑎 𝐿 𝑠,𝑖 .…”

Section: Micro-indentation Experimentsmentioning

confidence: 99%

Indentation deformation and cracking behavior of hydrated aluminoborate glasses

et al. 2021

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Aluminoborate glasses have recently been found to feature high resistance to crack initiation during indentation due to a highly flexible network structure. In cesium aluminoborate glasses, it has been found that the use of a simple post‐treatment, namely aging in a humid atmosphere, can further improve this resistance. To better understand the mechanical properties of this glass family upon humid aging, we here study the effect of aging conditions on the structure and mechanical properties of Li,K,Cs‐aluminoborate glasses. As expected, we find that higher humidity and longer aging time cause more pronounced permeation of atmospheric water into the glasses. Due to their denser structure and stronger modifier‐oxygen bonds, the humid aging has a relatively smaller effect on the mechanical properties of Li‐ and K‐containing glasses relative to Cs‐containing glasses, with the latter achieving an ultrahigh crack resistance. We find that the humid aging leads to the formation of a hydration layer in the Cs‐aluminoborate glass surface, with a thickness of around 26 μm upon aging at 23 °C with 40% relative humidity for 7 days. Moreover, a remarkable indentation behavior, that is, the observation of μm‐sized shear bands inside the imprint of the Cs‐glass upon aging at 60% relative humidity is reported. Taken as a whole, the work provides guidelines for how to control the humid aging rate as a function of relative humidity and temperature to form a hydration layer and thus achieve improved crack resistance in such glasses.

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Indentation cracking and deformation mechanism of sodium aluminoborosilicate glasses

Cited by 21 publications

References 38 publications

Influence of Al2O3 Addition on Structure and Mechanical Properties of Borosilicate Glasses

Influence of Al2O3 Addition on Structure and Mechanical Properties of Borosilicate Glasses

Exploratory Study on the Fracture Resistance of Cast Glass

Indentation deformation and cracking behavior of hydrated aluminoborate glasses

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