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US 4,255,213 AGranted
Method for producing solar collector plates
AssigneeAmax Inc.
InventorJames D. Redmond
Life of this patent
Estimating the term…
Abstract
A solar collector plate made of stainless steel or a metal having a nickel-flash coating is immersed in a molten dichromate salt bath at a temperature between about 375.degree. C. and about 500.degree. C. sufficiently long to provide a selective oxide coating which has a Figure of Merit of at least about 4. The oxide coating is continuous, has a microscopically nodular texture with the average nodule size being at least about 5000 A and displays a Figure of Merit of at least about 4.
Claims7
In a method for producing a solar collector which comprises a collector box;
- a collector plate through which a heat exchange fluid circulates for transferring heat from said heat plate to a remote location, said plate being placed in said collector box and having a collector surface of stainless steel or another metal flash coated with nickel or chromium which surface is provided with an oxide layer to provide a selective coating and a glass cover for enclosing said plate, the improvement which comprises immersing the collector plate in a molten bath of a dichromate salt of at least one metal selected from the group consisting of sodium and potassium for a time sufficient to provide the collector surface with an oxide coating having a Figure of Merit of between about 4 and about 13.
Dependencies are inferred from the claim text.