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Fracture of Glass in Vacuum
Author(s) -
WIEDERHORN S. M.,
JOHNSON H.,
DINESS A. M.,
HEUER A. H.
Publication year - 1974
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1974.tb10917.x
Subject(s) - materials science , composite material , viscous flow , fracture (geology) , diffusion , fracture mechanics , stress intensity factor , glass transition , fracture toughness , torr , alkali metal , thermodynamics , mechanics , chemistry , polymer , physics , organic chemistry
The fracture of 6 glasses was studied in vacuum, <10 −4 torr (10 −2 N/m 2 ), as a function of temperature from 25° to 775°C. Subcritical crack growth was observed in 4 of the glasses. Activation energies for crack motion ranged from 60 to 176 kcal/mol. The glasses which did not exhibit slow crack growth were “anomalous” glasses with abnormal thermal and elastic properties. Critical stress intensity factors for these 2 glasses increased ∼10% as the temperature increased to ∼600°C. It is felt that subcritical crack growth is not the result of alkali‐ion diffusion or viscous flow but rather of a thermally activated growth process which depends on the crack‐tip structure in the glass. A narrow cohesive region at the crack tip favors subcritical crack growth, whereas a wide region favors abrupt fracture.