Doctoral Dissertations
Keywords and Phrases
Aqueous dissolution; Aluminophosphate
Abstract
"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.
Advisor(s)
Brow, Richard K.
Committee Member(s)
Day, D. E.
Hayden, Joseph
Rahaman, M. N., 1950-
Schwartz, Robert W.
Wronkiewicz, David J.
Department(s)
Materials Science and Engineering
Degree Name
Ph. D. in Ceramic Engineering
Publisher
University of Missouri--Rolla
Publication Date
Fall 2005
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
Pagination
xiv, 173 pages
Note about bibliography
Includes bibliographical references.
Rights
© 2005 Brad Conrad Tischendorf, All rights reserved.
Document Type
Dissertation - Restricted Access
File Type
text
Language
English
Subject Headings
Glass -- CorrosionCorrosion and anti-corrosives
Thesis Number
T 8847
Print OCLC #
76913515
Electronic OCLC #
1089949006
Recommended Citation
Tischendorf, Brad C., "Interactions between water and phosphate glasses" (2005). Doctoral Dissertations. 1648.
https://scholarsmine.mst.edu/doctoral_dissertations/1648
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