Glass Durability Along the Compositional Continuum Between a Phase Separated Frit and a Homogeneous Glass
Glass Durability Along the Compositional Continuum Between a Phase Separated Frit and a Homogeneous Glass

Author:

Publisher:

Published: 1999

Total Pages: 5

ISBN-13:

DOWNLOAD EBOOK

Seven non-radioactive glass compositions spanning the range of wastes to be processed in the Defense Waste Processing Facility (DWPF) were studied prior to start up of the Processing DWPF melter. These glasses were produced by Corning Glass Works and were designated Waste Compliance Plan (WCP) glasses. New glasses were melted by adding Frit 202 to the WCP-Purex glass and the resulting glass compositions were examined for amorphous phase separation using Transmission Electron Microscopy (TEM). The durability of the glasses was measured using the Product Consistency Test (PCT), ASTM C 1285-94.

Glass Durability Along the Compositional Continuum Between a Phase Separated Frit and a Homogenous Glass
Glass Durability Along the Compositional Continuum Between a Phase Separated Frit and a Homogenous Glass

Author:

Publisher:

Published: 1999

Total Pages:

ISBN-13:

DOWNLOAD EBOOK

Seven non-radioactive glass compositions spanning the range of wastes to be processed in the Defense Waste Processing Facility (DWPF) were studied prior to start up of the Processing DWPF melter. These glasses were produced by Corning Glass Works and were designated Waste Compliance Plan (WCP) glasses. New glasses were melted by adding Frit 202 to the WCP-Purex glass and the resulting glass compositions were examined for amorphous phase separation using Transmission Electron Microscopy (TEM). The durability of the glasses was measured using the Product Consistency Test (PCT), ASTM C 1285-94.

Method of Determining Glass Durability
Method of Determining Glass Durability

Author:

Publisher:

Published: 1998

Total Pages:

ISBN-13:

DOWNLOAD EBOOK

A process for determining one or more leachate concentrations of one or more components of a glass composition in an aqueous solution of the glass composition by identifying the components of the glass composition, including associated oxides, determining a preliminary glass dissolution estimator, .DELTA. G.sub.p, based upon the free energies of hydration for the component reactant species, determining an accelerated glass dissolution function, .DELTA. G.sub.a, based upon the free energy associated with weak acid dissociation, .DELTA. G.sub.a.sup. WA, and accelerated matrix dissolution at high pH, .DELTA. G.sub.a.sup. SB associated with solution strong base formation, and determining a final hydration free energy, .DELTA. G.sub.f. This final hydration free energy is then used to determine leachate concentrations for elements of interest using a regression analysis and the formula log.sub. 10 (N C.sub.i (g/L))=a.sub.i +b.sub.i .DELTA. G.sub.f. The present invention also includes a method to determine whether a particular glass to be produced will be homogeneous or phase separated. The present invention is also directed to methods of monitoring and controlling processes for making glass using these determinations to modify the feedstock materials until a desired glass durability and homogeneity is obtained.

Phase-separation Phenomena in Glasses
Phase-separation Phenomena in Glasses

Author: E. A. Poraj-Košic

Publisher: Springer Science & Business Media

Published: 1973

Total Pages: 232

ISBN-13:

DOWNLOAD EBOOK

The First All-Union Symposium on Phase-Separation Phenomena in Glasses was held in Lenin grad from April 16 to 18, 1968. The symposium was organized by the Section of the structure of glass and the nature of the glassy state of the Scientific Council for the problem "New Tech nical Materials and Coatings Based on Glass and Refractory Compounds" of the State Committee for Science and Technology of the Council of Ministers of the USSR, by the Scientific Council for the problem "Physicochemical Principles of Production of New Heat-Resistant Inorganic Mate rials" of the Division of Physical Chemistry and Technology of Inorganic Materials, Academy of Sciences of the USSR, by the Leningrad regional board of the D. 1. Mendeleev All-Union Chemi cal Society, and by the 1. V. Grebenshchikov Institute of Silicate Chemistry, Academy of Sciences of the USSR. The present collection consists of the Proceedings of the Symposium and is No. 3 in Vol. 5 of the series "The Glassy State," published by the Academy of Sciences of the USSR since 1955. The book contains the results of theoretical and experimental investigations of phase sep aration of glasses into two glassy phases, and of the influence of this submicroscopically heter ogeneous structure on certain properties of glass. Metastable phase separation in glasses was discovered about 10 years ago.

Impact of Cooling Rate on the Durability of PHA Glasses
Impact of Cooling Rate on the Durability of PHA Glasses

Author:

Publisher:

Published: 2001

Total Pages: 5

ISBN-13:

DOWNLOAD EBOOK

This study was conducted to determine the effect, if any, on the PCT responses of glasses cooled at different rates. Two bounding cooling profiles were used in this study: rapidly quenched and a canister centerline cooling curve. Glasses were selected based on a number of criteria, but mainly to challenge the regions where amorphous phase separation is expected based upon current model predictions. The current DWPF homogeneity constraint, imposed to preclude regions of phase separation, predicted that most of the glasses selected would be phase separated. It was, therefore, important to ensure that deleterious phase separation does not occur at either cooling profile. In this case, deleterious phase separation is defined as the formation of an amorphous phase in the glass that significantly decreases the glass durability as measured by the PCT response.

Effect of Phase Separation on the Physical and Chemical Properties of Glasses-Density and Chemical Durability
Effect of Phase Separation on the Physical and Chemical Properties of Glasses-Density and Chemical Durability

Author: Joseph H. Simmons

Publisher:

Published: 1974

Total Pages: 27

ISBN-13:

DOWNLOAD EBOOK

This report covers results from density and chemical durability measurements on a borosilicate glass widely used commercially for chemical glassware while the glass undergoes liquid-liquid immiscibility. A net decrease in density is observed during an isothermal heat-treatment below the transition temperature. This density or molar volume change is related to the effect of pressure on the phase transition temperature by means of equations derived herein. The chemical durability of the material is measured following the ASTM titration technique and shows a large degradation of chemical resistance to attack by water as a result of sub-immiscibility structure development. The effect is analyzed in terms of the change in composition of the phases associated with the immiscibility transition. (Author).

Prediction of Glass Durability as a Function of Glass Composition and Test Conditions
Prediction of Glass Durability as a Function of Glass Composition and Test Conditions

Author:

Publisher:

Published: 1988

Total Pages:

ISBN-13:

DOWNLOAD EBOOK

The long-term durability of nuclear waste glasses can be predicted by comparing their performance to natural and ancient glasses. Glass durability is a function of the kinetic and thermodynamic stability of glass in solution. The relationship between the kinetic and thermodynamic aspects of glass durability can be understood when the relative contributions of glass composition and imposed test conditions are delineated. Glass durability has been shown to be a function of the thermodynamic hydration free energy which can be calculated from the glass composition. Hydration thermodynamics also furnishes a quantitative frame of reference to understand how various test parameters affect glass durability. Linear relationships have been determined between the logarithmic extent of hydration and the calculated hydration free energy for several different test geometries. Different test conditions result in different kinetic reactivity parameters such as the exposed glass surface area (SA), the leachant solution volume (V), and the length of time that the glass is in the leachant (t). Leachate concentrations are known to be a function of the kinetic test parameter (SAV)t. The relative durabilities of glasses, including pure silica, obsidians, nuclear waste glasses, medieval window glasses, and frit glasses define a plane in three dimensional .delta.G/sub hyd/-concentration-(SAV)t space. At constant kinetic conditions, e.g., test geometry and test duration, the three dimensional plane is intersected at constant (SAV)t and the .delta.G/sub hyd/-concentration plots have similar slopes. The slope represents the natural logarithm of the theoretical slope, (12.303 RT), for the rate of glass dissolution. 53 refs., 4 figs.