| Autor: |
Brady, M. P., Fayek, M., Leonard, D. N., Meyer Iii, H. M., Thomson, J. K., Anovitz, L. M., Rother, G., Song, G.-l., Davis, B. |
| Předmět: |
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| Zdroj: |
Journal of The Electrochemical Society; 2017, Vol. 164 Issue 7, pC367-C375, 9p |
| Abstrakt: |
Magnesium Elektron North America, Madison, Illinois 62060, USA A sequential isotopic tracer study of corrosion film growth for Mg-3Al-1Zn-0.25Mn (AZ31B) and Mg-1.2Zn-0.25Zr-<0.5Nd (ZE10A) was conducted by 4 h immersion in H218O or D2 16O, followed by a 20 h immersion in a 0.01 wt% NaCl H218O or D216O solution. Sputter depth profiles were obtained for 16O, 18O, H, and D using secondary ion mass spectrometry (SIMS). Compared to the previous tracer study for these alloys in salt-free water, the addition of 0.01 wt% NaCl resulted in a transition from oxygen inward-dominated film growth to a component of mixed inward/outward film growth for both alloys. The hydrogen tracer behavior remained inward growing for AZ31B, and short-circuit, inward growing for ZE10A, in both pure water and in 0.01 wt% NaCl solution, with extensive penetration of D beyond the film and into the underlying alloy also observed for ZE10A. Analysis of the films by X-ray photoelectron spectroscopy (XPS) and cross-section scanning transmission electron microscopy (STEM) indicated intermixed Mg(OH)2 and MgO, with the relative fraction of Mg(OH)2 peaking near the center of the film. These findings suggest a decoupled film growth mechanism, with initial formation of oxide followed by NaCl-accelerated conversion to hydroxide, likely by both solid-state and dissolution-precipitation processes. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Supplemental Index |
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