Hardness and high pressure deformation mechanisms of glass

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Authors
Neely Jr., James E.
Issue Date
1969-05
Type
Electronic thesis
Thesis
Language
ENG
Keywords
Materials science glass science
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Abstract
The annealing behavior of indentations in Si02 and caO·Si02 glass was investigated. The effect of heat treatment on indentation depths in silica glass was determined on 400 and 600 gram indentations. During the first 1/4 hour of annealing of silica glass, large indentation depth recoveries were observed, after which little or no change was observed for several hours of annealing at temperature. It was found that the indentation depth which is observed after a given time at a specific temperature is, statistically, independent of previous heat treatment at lower temperatures. Since most indentation recovery occurred rapidly in the initial stage of annealing, the experimental activation energy characteristic of this process was determined from the initial rates of indentation recovery for temperatures from 6000 to lOOOoC. Experimental activation energies of approximately 4 Kcal/mole were evaluated for both loads. Approximately one-half of the indentation depth of silica glass was found to anneal out below Tg. Indentation depths of caO·Si02 glass recovered much less at temperatures below Tg, such that no analysis of an activation energy could be made.
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May 1969
School of Engineering
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Rensselaer Polytechnic Institute, Troy, NY
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