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US 5,470,664 AGranted
Hard anodic coating for magnesium alloys
AssigneeTechnology Applications Group, Inc.
InventorsDuane E. Bartak, Brian E. Lemieux, Earl R. Woolsey
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AssigneeTechnology Applications Group, Inc.
InventorsDuane E. Bartak, Brian E. Lemieux, Earl R. Woolsey
Estimating the term…
A two-step process for the coating of magnesium and its alloys is disclosed. The first step comprises immersing the magnesium workpiece in an aqueous solution comprising about 0.2 to 5 molar ammonium fluoride having a pH of about 5 to 8 and a temperature of about 40.degree. to 100.degree. C. The second step is an electrochemical treatment of the pretreated article in an aqueous electrolytic solution having a pH of at least about 12.5 and which solution comprises about 2 to 12 g/L of a aqueous soluble hydroxide, about 2 to 15 g/L of a fluoride-containing composition selected from the group consisting of fluorides and fluorosilicates, and about 5 to 30 g/L of a silicate. This process results in a superior coating which has increased abrasion and corrosion resistance.
A magnesium-containing article offering improved corrosion and abrasion resistance, the article comprising a magnesium-containing substrate coated with a first layer containing a continuum of magnesium fluoride, magnesium oxide, magnesium oxofluoride and silicon oxide.
Dependencies are inferred from the claim text.