Keywords and Phrases
Aqueous dissolution; Aluminophosphate
"The reactions between phosphate glasses and water have been characterized in a number of different environments. The weathering and aqueous dissolution properties of these glasses are presented under a range of temperature, humidity, and pH conditions.
During the dissolution process, water is first absorbed by the glass surface and hydrated the surface disassociated the phosphate network and modifying cations. Once disassociated, the cations and chains are removed congruently from the glass surface. During these experiments it has been found that the addition of high field strength modifiers or the change in glass structure from the meta toward the pyrophosphate composition may be unable to improve the durability of the glass systems on their own.
The weathering reactions of phosphate occur in a similar manner, with water initially absorbed by the glass surface and hydrating the modifiers and the phosphate network, isolating them from each other. It then continues with hydrolysis of the phosphate chains on the glass surface, and the production of a visible reaction layer, and can eventually lead to the precipitation of crystalline orthophosphate species on the glass surface. Modifying cations such as Al3+ that can form bonds with lower ionic character can help to prevent water from hydrating the glass network. The phosphate network itself can also become more resistant to hydration as shorter phosphate chains appear to form stronger P-O-M bonds and also may electrostatically repel water. These high field strength modifiers will, however, accelerate the hydrolysis process once the surface is hydrated.
In both weathering and dissolution, the combined effect of the modifying cations and the phosphate network should be taken into account when attempting to predict durability. Models are presented in this work that provide some additional understanding of the fundamental reaction mechanisms of phosphate glasses"--Abstract, page iv.
Brow, Richard K.
Day, D. E.
Rahaman, M. N., 1950-
Schwartz, Robert W.
Wronkiewicz, David J.
Materials Science and Engineering
Ph. D. in Ceramic Engineering
University of Missouri--Rolla
Journal article titles appearing in thesis/dissertation
- Glass corrosion background
- Aqueous reactions of aluminophosphate glasses
- Weathering reactions of phosphate glasses
- NMR study of reactions between aluminophosphate glasses and water
xiv, 173 pages
© 2005 Brad Conrad Tischendorf, All rights reserved.
Dissertation - Restricted Access
Library of Congress Subject Headings
Glass -- Corrosion
Corrosion and anti-corrosives
Print OCLC #
Electronic OCLC #
Link to Catalog Record
Full-text not available: Request this publication directly from Missouri S&T Library or contact your local library.http://laurel.lso.missouri.edu/record=b5729687~S5
Tischendorf, Brad C., "Interactions between water and phosphate glasses" (2005). Doctoral Dissertations. 1648.
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