Crystallization of a chemical conversion layer that forms on AZ91D magnesium alloy in carbonic acid
This investigation studied the crystallization of a chemical conversion layer that formed on AZ91D Mg alloy in carbonic acid. The layer was an amorphous precursor to a crystalline Mg-Al layered double hydrotalcite, which improved the corrosion resistance of the alloy. The precursor must be treated w...
Published in: | Corrosion Science |
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Main Authors: | , , |
Other Authors: | , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Elsevier Ltd.
2011
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Subjects: | |
Online Access: | http://hdl.handle.net/11455/43182 https://doi.org/10.1016/j.corsci.2011.07.035 |
Summary: | This investigation studied the crystallization of a chemical conversion layer that formed on AZ91D Mg alloy in carbonic acid. The layer was an amorphous precursor to a crystalline Mg-Al layered double hydrotalcite, which improved the corrosion resistance of the alloy. The precursor must be treated with a strongly alkaline solution, causing the leaching out of amphoteric Al3+. The leaching step evidently caused crystallization from an amorphous precursor layer to a crystalline coating. Nuclear magnetic resonance analysis indicated that Al3+, which was originally randomly coordinated with surrounding OH− in the precursor, coordinated octahedrally with OH− groups in the crystalline conversion coating. |
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