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US 4,963,198 AGranted
Composition and process for treating metal surfaces
AssigneeBrent Chemicals International Limited
InventorGeorge L. Higgins
Life of this patent
Estimating the term…
Abstract
An alkaline aqueous solution comprising hexavalent chromium, trivalent chromium, and a complexing agent for trivalent chromium sufficiently effective to solubilize at least 20 ppm of trivalent chromium forms a protective coating when contacted with zinc, aluminum, and particularly zinc-aluminum alloys.
Claims13
An aqueous alkaline solution suitable for forming a protective coating on zinc, aluminum, and alloys thereof, comprising:
- (a) dissolved hexavlent chromium in an amount in the range 8-75 ppm
- (b) a dissolved complexing agent for trivalent chromium ions;
- and
- (c) dissolved trivalent chromium in an amount in the range 20-700 ppm,
- said solution having a pH above 12.
2 more elements
A process for forming a protective coating on a surface of zinc, aluminum, or an alloy of zinc or aluminum, comprising
- contacting the surface with a solution comprising:
- (a) dissolved hexavlent chromium in an amount in the range 8-75 ppm;
- (b) a dissolved complexing agent for trivalent chromium ions;
- and
- (c) dissolved trivalent chromium in an amount in the range 20-700 ppm,
- said solution having a pH above 12;
- and
- then rinsing the surface.
5 more elements
Dependencies are inferred from the claim text.