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AssigneeElectro Chemical Engineering GmbH
InventorsEdith L. Schmeling, Benno Roschenbleck, Michael H. Weidemann
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A method of producing protective coatings that are resistant to corrosion and wear on magnesium and magnesium alloys by anodic oxidation. In order to obtain coatings that have little or no inherent color, that can be easily colored, and that provide a satisfactory adhesive base for lacquering or subsequent processing, a low-alkali aqueous electrolyte bath containing (a) borate or sulfonate anions and (b) phosphate and fluoride or chloride ions and adjusted to a pH of 5 to 11 and preferably 8 to 9 is employed. A direct current is applied and is either briefly turned off or its polarity incompletely reversed to allow the formation of manganese phosphate and magnesium fluoride or magnesium chloride and optionally magnesium aluminate.
A method of producing a protective coating that is resistant to corrosion and wear on magnesium or a magnesium alloy by anodic oxidation, comprising immersing the magnesium or magnesium alloy in a low-alkali aqueous electrolyte bath containing
A magnesium alloy coated with a protective coating containing magnesium phosphate and magnesium fluoride that is 15 to 30 .mu.m thick and resists wear with a loss of mass measuring less than about 20 mg following 10,000 revolutions in a Taber abraser (CS 10, 10 N).
Dependencies are inferred from the claim text.