Surface treatment on magnesium alloys

conference paper

English

Magnesium alloys are very prospective materials. They have very good mechanical properties and very low density. They are used in automotive industry, aerospace etc. On the other hand magnesium alloys have very low corrosion resistence. And this is the reason, why the protection of magnesium alloys against the corrosion is in focus. One of the most important protective methods are conversion coatings. Magnesium alloys AZ91, AZ61 and AZ31 were treated by phosphate-permanganate and chromate conversion coatings. Chromate coatings are very efficient conversion coatings but they cannot be used any more due to carcinogenic Cr(VI). In our case chromate conversion coating was however taken as standard. Aluminium in magnesium forms intermetallic phase beta (Mg17Al12). Magnesium alloy AZ91 contains more aluminium than AZ31 and AZ61, so the portion of intermetallic phase beta is bigger in magnesium alloy AZ91. Beta-phase has higher electrochemical potential, so in magnesium alloys it behaves like cathode. Then the problem to be solid by us is that more beta phase gives bigger micro-cells and the electrochemical corrosion is more significant.

Magnesium alloys, conversion coatings.

Magnesium alloys, conversion coatings.

TKACZ, J.; ZMRZLÝ, M.

2012

7. 12. 2012

Vysoké Učení Technické v Brně, Fakulta Chemická, Purkyňova 464/118, 612 00 Brno

978-80-214-4644-1

Studentská konference Chemie je život

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