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Environmental Degradation of Materials: Surface Chemistry Related to Stress Corrosion CrackingParallel experiments have been performed in order to develop a comprehensive model for stress cracking (SCC) in structural materials. The central objective is to determine the relationship between the activity and selectivity of the microstructure of structural materials to their dissolution kinetics and experimentally measured SCC kinetics. Zinc was chosen as a prototype metal system. The SCC behavior of two oriented single-crystal disks of zinc in a chromic oxide/sodium sulfate solution (Palmerton solution) were determined. It was found that: (1) the dissolution rate is strongly (hkil)-dependent and proportional to the exposure time in the aggressive environment; and (2) a specific slip system is selectively active to dissolution under applied stress and this slip line controls crack initiation and propagation. As a precursor to potential microgrvity experiments, electrophoretic mobility measurements of zinc particles were obtained in solutions of sodium sulfate (0.0033 M) with concentrations of dissolved oxygen from 2 to 8 ppm. The equilibrium distribution of exposed oriented planes as well as their correlation will determine the particle mobility.
Document ID
19860000632
Document Type
Other
Authors
Schwarz, J. A. (Syracuse Univ. NY, United States)
Date Acquired
August 12, 2013
Publication Date
May 1, 1985
Publication Information
Publication: NASA, Washington Microgravity Sci. and Appl. Program Tasks
Subject Category
ASTRONAUTICS (GENERAL)
Funding Number(s)
CONTRACT_GRANT: NAGW-466
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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