A Raman-spectroscopic study of indentation-induced structural changes in technical alkali-borosilicate glasses with varying silicate network connectivity
“…To ensure homogenous melts, the glasses with SiO 2 contents higher than 70 mol% were quenched in water and re-melted after drying. All melts were poured into preheated graphite molds (~20-50 K above the glass transition temperature) and cooled down to room temperature at a rate of 30 K/h, except for the Duran-type composition, which was cooled in the crucible, and the model glasses NBS A, C and D, which were quenched down to room temperature [33,34]. For comparison, commercially available SiO 2 (Suprasil, Heraeus Quarzglas GmbH & Co. KG) was analyzed as well.…”
Section: Glass Preparationmentioning
confidence: 99%
“…Data on T g and ρ are taken from Refs. [33][34][35] echoes. The shear modulus G, bulk modulus K and elastic modulus E as well as the Poisson ratio ν were calculated using the following relations, which are applicable for isotropic materials [39]:…”
Section: Ultrasonic Echographymentioning
confidence: 99%
“…However, higher modifier oxide concentrations (R N 0.5) cause NBO to form on trigonal borate groups, and/or on silicate tetrahedra. This coordination change makes borate containing glass systems very interesting for studying the material's response to indentation deformation, as the network can be manipulated with respect to the degree of polymerization, not only considering the number of non-bridging oxygen ions, but also considering the BO 3 /BO 4 ratio [32][33][34].…”
Section: Introductionmentioning
confidence: 99%
“…In the present study, we provide systematic data on the elastic properties, Poisson ratio, hardness, the relation between densification and volume conservative shear flow, and correlations to damage tolerance for a range of compositions of the well investigated alkaliborosilicate system [11,12,34]. We focus on variations of the R-and K-values, i.e., BO 3 /BO 4 ratios and also varying amounts of NBO, within the technologically most relevant part of the ternary (which also contains the regions of immiscibility).…”
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.
“…To ensure homogenous melts, the glasses with SiO 2 contents higher than 70 mol% were quenched in water and re-melted after drying. All melts were poured into preheated graphite molds (~20-50 K above the glass transition temperature) and cooled down to room temperature at a rate of 30 K/h, except for the Duran-type composition, which was cooled in the crucible, and the model glasses NBS A, C and D, which were quenched down to room temperature [33,34]. For comparison, commercially available SiO 2 (Suprasil, Heraeus Quarzglas GmbH & Co. KG) was analyzed as well.…”
Section: Glass Preparationmentioning
confidence: 99%
“…Data on T g and ρ are taken from Refs. [33][34][35] echoes. The shear modulus G, bulk modulus K and elastic modulus E as well as the Poisson ratio ν were calculated using the following relations, which are applicable for isotropic materials [39]:…”
Section: Ultrasonic Echographymentioning
confidence: 99%
“…However, higher modifier oxide concentrations (R N 0.5) cause NBO to form on trigonal borate groups, and/or on silicate tetrahedra. This coordination change makes borate containing glass systems very interesting for studying the material's response to indentation deformation, as the network can be manipulated with respect to the degree of polymerization, not only considering the number of non-bridging oxygen ions, but also considering the BO 3 /BO 4 ratio [32][33][34].…”
Section: Introductionmentioning
confidence: 99%
“…In the present study, we provide systematic data on the elastic properties, Poisson ratio, hardness, the relation between densification and volume conservative shear flow, and correlations to damage tolerance for a range of compositions of the well investigated alkaliborosilicate system [11,12,34]. We focus on variations of the R-and K-values, i.e., BO 3 /BO 4 ratios and also varying amounts of NBO, within the technologically most relevant part of the ternary (which also contains the regions of immiscibility).…”
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.
“…Winterstein-Beckmann et al conducted a Raman spectroscopic study in alkaliborosilicate glass and reported that indentationinduced structural changes depend on not only borate concentration but also silicate sub-network connectivity [15]. They also reported that the largest value of CR is not obtained for the composition that shows the highest values of densification to total indentation volume ratio.…”
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