Coins coated with nickel, copper and nickel and process for making such coins
First Claim
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1. A process for making a coin blank or like articles comprising:
- a) cleaning a ferrous metal blank so that it will be essentially free of oxide;
b) electroplating said blank with a strike of nickel;
c) electroplating the strike of nickel with a coating of copper by first depositing a thin, initial film of copper at a low current density in a bath that is about 1/6 to 1/4 of the full current density and then depositing the remainder of the copper coating at a full current density in the same bath to minimize or avoid bridging of micropores in the ferrous metal blank.
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Abstract
This invention overcomes problems such as pinholes and blisters in making plated coin blanks and similar articles. A ferrous metal blank is electroplated with a strike of nickel, following which a coating of copper is applied at an initial low current density followed by full current density to minimize bridging. The low current density may be about 1/6 to 1/4 of the full current density. Preferably an outer layer of nickel is applied, also at an initial low current density, followed by full current density. Annealing before or after application of the final layer of nickel is advisable. This invention also relates to the resulting coin blank and coins.
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Citations
14 Claims
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1. A process for making a coin blank or like articles comprising:
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a) cleaning a ferrous metal blank so that it will be essentially free of oxide; b) electroplating said blank with a strike of nickel; c) electroplating the strike of nickel with a coating of copper by first depositing a thin, initial film of copper at a low current density in a bath that is about 1/6 to 1/4 of the full current density and then depositing the remainder of the copper coating at a full current density in the same bath to minimize or avoid bridging of micropores in the ferrous metal blank. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A process for making a coin blank or like articles comprising:
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a) cleaning a ferrous metal blank so that it will be essentially free of oxide; b) electroplating said blank with a strike of nickel; c) electroplating the strike of nickel with a coating of copper by first depositing a thin, initial film of copper at a low current density in a bath that is about 1/6 to 1/4 of the full current density and then depositing the remainder of the copper coating at a full current density in the same bath to minimize or avoid bridging of micropores in the ferrous metal blank. d) electroplating the copper with an outer layer of nickel by first depositing a thin, initial film of nickel at a low current density that is about 1/6 to 1/4 of the full current density and then depositing the remainder of the nickel coating at a full current density to minimize or avoid bridging of micropores in the ferrous metal blank. - View Dependent Claims (10, 11, 12, 13, 14)
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Specification