Glasses, Optical Materials, and Devices: Current Issues in Science & Technology: Glass-environment Interactions
Program Organizers: Jincheng Du, University of North Texas; S. Sundaram, Alfred University

Wednesday 8:00 AM
October 2, 2019
Room: A106
Location: Oregon Convention Center

Session Chair: John Vienna, PNNL; Jincheng Du, University of North Texas; Nicholas Smith, Corning Inc.

8:00 AM  Invited
Commonalities in Corrosion Mechanisms across Materials: Joseph Ryan1; 1Pacific Northwest National Laboratory
    Differences in atomic structure and electronic properties cause large differences in corrosion behavior between materials classes. These are significant enough such that separate fields of science have developed for metaIlurgical corrosion, geochemistry, and glass corrosion. There are commonalities among the fields, however, such that much can be learned from evaluating aqueous durability through the eyes of different materials classes. Recent findings by an Energy Frontier Research Center termed “Waste Performance and Design” will be leveraged to provide examples of mechanisms where this is the case. The talk will focus on similarities and differences in the mechanisms of corrosion and emphasize where cross-class experimental and characterization techniques informed the result.

8:40 AM  Invited
What Does “Chemical Durability” Mean to a Glass Industry and Current Challenges?: Aize Li1; 1Corning Inc.
    Chemical Durability is an important attribute in glass industry and it is used in nearly every stage of a glass product in its lifetime from manufactory, storage, applications to disposal. In this presentation, we will start with an overview of the capabilities of Chemical Durability group in Corning including various durability tests and cut-edge techniques used to support Corning business. We will then give a few examples to demonstrate some challenges associated with “chemical durability” of glasses, focusing on the discussion of the influence of chemical or environmental corrosion on glass optical properties and surface defect formation. Some examples of challenges include minimizing the glass aging effect on optical properties, inhibiting the effect of dissolved species in solutions on glass dissolution and optical properties, and achieving a model to predict a glass composition to meet certain optical target.

9:10 AM  Invited
Nuclear Waste Glass Composition Control for Predictable Chemical Durability: John Vienna1; 1Pacific Northwest National Laboratory
    Nuclear waste glasses are designed to simultaneously satisfy many constraints. Constraints related to chemical durability are particularly important as one of the primary objectives of nuclear waste vitrification is to limit the release of radionuclides to the environment. Chemical durability test responses are used in the U.S. to demonstrate sufficient chemical durability of nuclear waste glasses including the vapor hydration test (VHT) (for Hanford low-activity waste [LAW]) and the product consistency test (PCT) (both LAW and high-level wastes). The state of the art in models used to predict the influence of composition on VHT and PCT will be described. New approaches are being developed to predict the long-term dissolution rates in glass including the propensity for accelerated corrosion as functions of glass composition and environmental parameters. These approaches will be introduced, and initial results presented.

9:40 AM  
Interactions between Modifier Identity, Network Connectivity, and Solution pH in Corrosion of Aluminosilicate Glasses: Nicholas Smith1; Robert Schaut1; Jonathan Icenhower1; Elzbieta Bakowska1; Adama Tandia1; 1Corning Incorporated
    Many researchers versed in silicate glass corrosion may be familiar with “general” structure-composition principles that link with chemical durability. These guidelines generally demonstrate a correlation between improved durability and higher silica content and degree of network connectivity, as well as with the field strength of network-modifying cations. Much more difficult to discern, however, is the relative strength of these factors in different combinations of structure and media—i.e. how these different factors interrelate in a holistic sense across a wide range of glass structures, or how rates change for the same glasses when traversing a wide range of solution pH. In this talk, we describe important trends observed in forward-rate durability across a span of nearly 50 ternary aluminosilicate glass compositions, calling particular attention to interactions between structural factors such as modifier identity and network connectivity, and how it varies in aqueous media from highly acidic to highly basic pH.

10:00 AM Break

10:20 AM  Invited
Understanding Water-silicate Glass Interactions from Reactive Potential Based Simulations: Jincheng Du1; 1University of North Texas
    Interaction of silicate glass and water is critical to the understanding of corrosion of glasses for applications ranging from windows and containers in everyday life to high technology field such as bioactive glass and nuclear waste immobilization. In this talk, I will present progresses of understanding of water-glass interaction from reactive potential based atomistic computer simulations. I will first present results of the water-silica glass interaction. Surface reaction, silanol group formation and porous silica gel layer formation will then be presented. Lastly, study of sodium silicate glass surface reaction with water will presented where mechanistic understanding from long time MD simulations provide insight of the chemical reaction and transport behaviors during silicate glass interaction with aqueous environment.

10:50 AM  Invited
Water Affects the Properties of Silica and the Silica Surface Affects the Properties of Water: Atomistic Mechanisms: Jesse Lentz1; Stephen Garofalini1; 1Rutgers University
    The interactions of water with silica surfaces affect proton transfer (PT) in a manner different from that in bulk water. This is because of a dependence of such PT upon hydrogen bonding, 1st and 2nd shell waters, and reorientation times of the H-bond that are affected by the presence of the interface with silica. Conversely, water absorbed into silica affects volume changes that modify surface relaxation and strength. Using a highly accurate reactive interatomic potential that matches many water properties and proton transfer consistent with ab-initio calculations, the behavior of water at the glass surface and the effect of the surface on proton transfer has been determined. The resulting reactions are also relevant in relation to high proton transport in wet mesoporous silica observed experimentally. In addition, the effect of water absorbed into silica on the volume change that can affect relaxation will also be discussed on the atomistic level.

11:20 AM  
Molar Volume of SiOH Estimated from Swelling Strains: Sheldon Wiederhorn1; Karl Schell2; Theo Fett2; 1National Institute of Standards and Technology; 2Karlsruhe Institute of Technology(KIT)
    As water diffuses into silica glass it reacts with the silica network to generate hydroxyl groups that cause a volume swelling of the glass. We discuss this effect quantitatively for cases in which hydroxyl groups were produced either by gamma-irradiation of hydrogen saturated silica glass, or by high-temperature diffusion of water into silica glass. From volume swelling measurements, the partial molar volume of hydroxyl groups for both treatments is determined to be 7.5 cm3/mol. Since two moles of SiOH are generated for each mole of water reacting with the glass, the reaction volume, ΔV̅, is 15.0 cc/mole.