Corrosion resistant metal composite with metallic undercoat and chromium topcoat
First Claim
1. A coated metal substrate having enhanced corrosion resistance and protected by a coating composite comprising a thin metallic undercoating layer of a metal combination having at least one metal selected from the group consisting of zinc, nickel, iron, chromium, aluminum and cobalt, and a substantially resin-free topcoat layer from a hexavalent-chromium-containing bonding coating composition heat-curable to a water resistant protective coating, said topcoat layer containing particulate metal as well as above 20 milligrams per square foot of coated metallic undercoating of chromium, as chromium, in non-elemental form, said composition containing hexavalent-chromium-providing-substance in liquid medium.
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Accused Products
Abstract
A coating composite provides extended corrosion resistance for substrate metals. The thin metallic undercoat of the composite contains combined metals. The heat curable and substantially resin free topcoat is established from composition containing chromium in non-elemental form, which topcoat composition may further contain particulate metal, all in liquid medium. In addition to outstanding corrosion resistance, the composite can retain substrate weldability as well as achieving formability, while further enhancing paintability and weatherability.
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Citations
21 Claims
- 1. A coated metal substrate having enhanced corrosion resistance and protected by a coating composite comprising a thin metallic undercoating layer of a metal combination having at least one metal selected from the group consisting of zinc, nickel, iron, chromium, aluminum and cobalt, and a substantially resin-free topcoat layer from a hexavalent-chromium-containing bonding coating composition heat-curable to a water resistant protective coating, said topcoat layer containing particulate metal as well as above 20 milligrams per square foot of coated metallic undercoating of chromium, as chromium, in non-elemental form, said composition containing hexavalent-chromium-providing-substance in liquid medium.
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18. A coated metal substrate having enhanced corrosion resistance and protected by a coating composite comprising a thin metallic electrodeposited undercoating layer containing metals in alloy form and including from about 40 to at most 95 weight percent zinc, and a heat curable, substantially resin free topcoat layer from hexavalent-chromium-containing bonding coating composition curable to a water resistant protective coating, said topcoat layer containing above about 50 milligrams per square foot of particulate metal as well as above about 25 milligrams per square foot of coated metallic undercoating of chromium, as chromium, in nonelemental form, said composition containing hexavalent-chromium-providing-substance in liquid medium.
- 19. A coated metal article in sheet or strip form having on one or both faces of said formed article a thin metallic undercoating layer of a metal combination having at least one metal selected from the group consisting of zinc, nickel, iron, chromium, aluminum and cobalt, while further having on one or both faces of said article a heat curable, substantially resin free topcoat layer from hexavalent-chromium-containing bonding coating composition curable to a water resistant protective coating, said topcoat layer containing particulate metal as well as above 20 milligrams per square foot of coated metallic undercoating of chromium, as chromium, in non-elemental form, said composition containing hexavalent-chromium-providing-substance in liquid medium.
Specification