Plasticity, crack initiation and defect resistance in alkali-borosilicate glasses: From normal to anomalous behavior

Abstract

We provide a comprehensive description of the defect tolerance of sodium-borosilicate glasses upon sharp contact loading. This is motivated by the key role which is taken by this particular glass system in a wide variety of applications, ranging from electronic substrates, display covers and substrates for biomedical imaging and sensing to, e.g., radioactive waste vitrification. The present report covers the mechanical properties of glasses in the Na 2 O-B 2 O 3 -SiO 2 ternary over the broad range of compositions from pure SiO 2 to binary sodium-borates, and crossing the regions of various commercially relevant specialty borosilicate glasses, such as the multi-component Duran-, Pyrex-and BK7-type compositions and typical soda-lime silicate glasses, which are also included in this study. In terms of structure, the considered glasses may be separated into two groups, that is, one series which contains only bridging oxygen atoms, and another series which is designed with an increasing number of nonbridging oxygen ions. Elastic moduli, Poisson ratio, hardness as well as creep and crack resistance were evaluated, as well as the contribution of densification to the overall amount of indentation deformation. Correlations between the mechanical properties and structural characteristics of near-and mid-range order are discussed, from which we obtain a mechanistic view at the molecular reactions which govern the overall deformation reaction and, ultimately, contact cracking.

Influence of Cooling Rate on Cracking and Plastic Deformation during Impact and Indentation of Borosilicate Glasses

“…It provides different analysis parameters: Usually, hardness is determined using the Oliver-Pharr technique Pharr, 1992, 2004) and is given by: Malchow et al (2015). b Taken from the study by Limbach et al (2015). c Determined by ultrasonic echography.…”

“…An echometer (model 1077, Karl Deutsch GmbH) working with an accuracy of ±1 ns was employed. More information on ultrasonic measurements and how elastic properties such as shear modulus G, bulk modulus K, and Young's modulus E, and Poisson ratio ν can be found elsewhere (Limbach et al 2015;Möncke et al, 2016).…”

“…For reasons of charge balance, an overcoordination of oxygen ions from twofold to threefold is also required, a mechanism that has been described for vitreous B2O3 under pressure (Lee et al, 2005). Limbach et al (2015) compiled a review on the mechanical properties of ternary borosilicate glasses comparing their own experimental data with literature values and trying to highlight trends with varying composition and structural variations of these glasses.…”

Indentation cracking behaviour and structures of nanophase separation of glasses

“…In order to understand these cracking behaviour of various glasses, several physical parameters, such as the density, Poisson's ratios and the coordination of boron in the glass have been correlated with the cracking behaviour. (10)(11)(12)(13)(14) It is well known that phase structures influence certain physical and chemical properties of glasses. (15)(16)(17) It has been reported that the fracture toughness of glasses is influenced by the phase separated structure.…”

Composition dependence of crack formation probability in aluminoborosilicate glass

“…In the sodium-borosilicate ternary system, glasses that preferred compaction under an indenter showed higher crack resistance [24]. The deformation behavior, shear-driven or densification-driven, was affected by the incorporation of SiO 2 and/ or B 2 O 3 and the ratio of Na 2 O/B 2 O 3 [25].…”