METHOD OF GENERATING CORROSION AND WEAR RESISTANT PROTECTION LAYERS ON MAGNESIUM AND MAGNESIUM ALLOYS

摘要

To produce corrosion- and wear-resistant protective coatings on magnesium or magnesium alloys by anodic oxidation, use is made of a low-alkali aqueous electrolytic bath which contains… a) borate or sulphate anions, and… b) phosphate and fluoride or chloride ions… and which is adjusted to a pH of 5 to 11, preferably 8 to 9. The applied direct current is interrupted for a short time or partially reversed in order to permit the formation of magnesium phosphate and magnesium fluoride or chloride and, possibly, magnesium aluminate. This produces coatings without or with only very slight inherent coloration which can readily be coloured and which yield a good adhesive base for lacquer coatings or post-treatments.