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  1. Abstract

    Machine learning (ML) is emerging as a powerful tool to predict the properties of materials, including glasses. Informing ML models with knowledge of how glass composition affects short-range atomic structure has the potential to enhance the ability of composition-property models to extrapolate accurately outside of their training sets. Here, we introduce an approach wherein statistical mechanics informs a ML model that can predict the non-linear composition-structure relations in oxide glasses. This combined model offers an improved prediction compared to models relying solely on statistical physics or machine learning individually. Specifically, we show that the combined model accurately both interpolates and extrapolates the structure of Na2O–SiO2glasses. Importantly, the model is able to extrapolate predictions outside its training set, which is evidenced by the fact that it is able to predict the structure of a glass series that was kept fully hidden from the model during its training.

     
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  2. Abstract

    The impact of microstructure on hardness in phase‐separated calcium aluminosilicate glasses is investigated. Changes in hardness are governed by microstructure deformations that occur during indentation. Phase separation leads to decreased hardness due to the incongruent yielding of the droplet and matrix phases. Moreover, the deformation of microstructures possessing dilute, spherical droplets did not have a significant impact on hardness. Microstructures characterized by concentrated, acicular droplets were found to deform through a process of droplet coalescence. This process absorbs additional energy during yielding and results in glasses that deform through droplet coalescence possessing improved hardness.

     
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  3. Abstract

    The mixed modifier effect (MME) is one of the most challenging puzzles in the field of oxide glasses, as there exists no universal quantitative theoretical model for accurately describing and predicting the nonlinear deviation of property values. In this paper, pairwise and ternary interactions are examined experimentally to understand the MME in a series of aluminosilicate glasses. By keeping the glass network former concentration constant and adjusting the molar ratios of three network modifiers (Na2O, K2O, and CaO), the MMEs in glass transition temperature (Tg), Vickers hardness (Hv), and activation energy (Ea) for aqueous dissolution for each modifier cation are investigated. We examine whether a pairwise interaction model is sufficient, or if ternary interactions also need to be included to predict the MME in these aluminosilicate glass systems. This work reveals that the pairwise model can be used to predict the MME forTgin complex multiple‐modifier glass systems using only two‐body interaction factors. However, ternary mixed‐modifier interactions are present in other properties such asHvandEa.

     
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  4. Abstract

    The field strength (FS) effect of six different network modifiers on the elastoplastic properties of aluminoborosilicate glasses was explored using a volumetric recovery study. This work, in conjunction with Part I, explored the intersection of hardness, crack resistance, and other physical properties with glass elasticity. Results showed that (1) the elastic volume fraction decreased with FS for both the alkali and alkaline earth (AE) glasses; (2) the Poisson's ratio did not trend with pile‐up or shear flow volume fraction; (3) the elastic‐to‐plastic deformation ratio increased with applied load and decreased with modifier FS for both the alkali and AE glasses; and (4) an increase in plasticity correlated with increased hardness, crack resistance, and elastic moduli.

     
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  5. Abstract

    The modifier field strength (FS) is believed to play an important role in determining the elastic–plastic responses of aluminoborosilicate (ABS) glasses, but its effect is not well understood. Three novel alkali and three alkaline earth (AE) ABS compositions were created for this study which is the first part of two studies that explored the elastoplastic responses of these glasses. Six compositions were designed using different network modifiers (NWMs) to cover a range of cation FS. The glasses were also designed such that the concentrations of NWM and Al2O3were similar, which maximized the three‐coordinated boron fraction in the network. It is well known that modifier FS can affect the coordination number (CN) of Al and B in an ABS glass structure, for example, a higher FS modifier can promote B3 → B4and higher [Al5,6], but the degree of this depends on network former (NWF) ratios. Previous work used solid‐state NMR spectroscopic analysis on the current glasses to find that there was variation between [B4] and [Al4] between the two glass series (alkali vs. AE) but that was attributed to synthesis factors and no trend with FS was associated with the varying NWF CN. Further,29Si ssNMR showed no evidence of NBOs which made sense based on composition. The conclusion, therefore, was that there was a far greater correlation with modifier FS for the increased mechanical and physical properties rather than the CN of Al and B. Part I of the current work focused on the elastic moduli, Poisson's ratio, the indentation size effect (ISE), and the bow‐in parameter. This part laid out the foundation to investigate the intersection of these elastoplastic properties with hardness and crack resistance as a function of NWM FS. Results showed that: (i) the Young's, bulk, and shear moduli increased with modifier FS, whereas Poisson's ratio did not trend with FS; (ii) the alkali glasses had a significantly higher magnitudes of ISE compared to the AE glasses; and (iii) the bow‐in parameter was load dependent and decreased with modifier FS at the highest indentation load.

     
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