1 January 1991 Moisture- and water-induced crack growth in optical materials
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Abstract
A number of optically important materials such as ZnS, SiO2, SiO2-TiO2, GaAs, and heavy metal fluoride (e.g., ZBLAN) glasses are subject to moisture- and/or liquid water-induced crack growth. A notable exception to this behavior appears to be Si. Such environmentally enhanced crack growth can lead to ultimate failure in service at stresses well below those expected from normal strength tests. The sensitivity of a material to water can be obtained by determining a crack growth parameter, N. This parameter can be combined with other easily obtainable fracture information which include measures of the strength and strength distribution to create a lifetime design diagram using fracture mechanics concepts. Methods for determining these fracture parameters including direct crack growth measurements and dynamic fatigue are reviewed, and the influence of environmental water on the materials is discussed. Crack growth mechanisms including physical (dielectric) and chemical reaction mechanisms are discussed, and lifetime design diagrams which can be used to determine stress levels in service are presented.
© (1991) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
David C. Cranmer, David C. Cranmer, Stephen W. Freiman, Stephen W. Freiman, Grady S. White, Grady S. White, Alan S. Raynes, Alan S. Raynes, } "Moisture- and water-induced crack growth in optical materials", Proc. SPIE 1330, Optical Surfaces Resistant to Severe Environments, (1 January 1991); doi: 10.1117/12.22637; https://doi.org/10.1117/12.22637
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