Copper alloy clad for coinage
AssigneeOlin Corporation
InventorsJohn F. Breedis, Derek E. Tyler
Life of this patent
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Abstract
There is provided a metallic composite useful for coinage. The core is formed from a copper alloy that contains between 50% and 99.0% copper, has a room temperature electrical conductivity in excess of 25% IACS an initial yield strength in excess of 10,000 psi and a dynamic softening response onset at a temperature in the range of 200.degree. C.-400.degree. C. The cladding layers have an initial yield strength more than that of the core and a gold color. The strengthening response of the core during cladding is similar to that of the cladding layers making the metallic composites resistant to corrugation. Reducing corrugation increases the sensitivity of electromagnetic coin discriminators.
Claims22
A metallic composite useful as a coinage material, comprising:
- a core formed from a copper base alloy that contains in excess of 50% by weight copper, but less than 99.0% by weight copper and has a room temperature electrical conductivity in excess of 25% IACS, an initial, before cladding, yield strength in excess of 10,000 psi and has a dynamic softening response onset at a temperature of from about 200.degree. C. and about 400.degree. C.;
- and
- cladding layers metallurgically bonded to both sides of said core, said cladding layers having both an initial yield strength greater than that of said core and a gold color.
A planchet comprising:
- a core consisting essentially of, by weight, from about 68.5% to about 99.0% copper and the balance zinc;
- and
- first and second cladding layers metallurgically bonded to opposing sides of said core, said first and second cladding layers having an initial yield strength more than the yield strength of said core, a gold color and a variation in thickness of each cladding layer being less than about 7%.
Dependencies are inferred from the claim text.