# US 8,771,591 B1 · Silver alloy with high tarnish resistance

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- Number: US 8,771,591 B1
- Document ID: US8771591B1
- Status: Granted
- Kind: B1
- Application number: 12/556,461
- Filed: 2009-09-09
- Granted: 2014-07-08
- Earliest claimed: 2009-09-09
- Assignees: American Bullion Investment Company, Inc.
- Applicants: Charles Bennett
- Inventors: Charles Bennett
- Web page: https://patentgrep.com/patent/US8771591B1

## CPC

- C22C 5/06: Alloys based on silver
- C22C: ALLOYS (treatment of alloys C21D, C22F)

## Abstract

A high tarnish resistant silver alloy composition formulated for jewelry and flatware manufacture is provided. In certain implementations, the alloy contains about 92%-97% by weight silver, about 0.25%-3.5% by weight palladium, about 0%-3.5% by weight platinum, about 0%-2.5% by weight gold, about 0.1%-1.0% by weight copper, about 0.5%-3.5% by weight zinc, about 0.1%-1.5% by weight tin, about 0.25%-1.5% by weight indium, about 0.03%-1.1% by weight silicon, about 0%-0.5% by weight germanium, about 0.15%-0.5% by weight gallium, about 0.25%-0.5% by weight cobalt and about 0%-0.5% by weight ruthenium. These unique combinations of elements result in the alloys with the tarnish resistance superior to typical 10K gold alloy.

## Claims

### Claim 1

An alloy composition consisting essentially of about 95% by weight silver, about 0.25% by weight palladium, about 0.4% by weight copper, about 2.75% by weight zinc, about 0.1% by weight tin, about 1% by weight indium, about 0.05% by weight silicon, about 0.2% by weight gallium, and about 0.25% by weight cobalt.

### Claim 2

An alloy composition consisting essentially of about 95% by weight silver, about 1% by weight palladium, about 0.45% by weight copper, about 1.45% by weight zinc, about 0.35% by weight tin, about 0.9% by weight indium, about 0.05% by weight silicon, about 0.35% by weight germanium, about 0.2% by weight gallium, and about 0.25% by weight cobalt.

### Claim 3

An alloy composition consisting essentially of about 95% by weight silver, about 1% by weight palladium, about 0.5% by weight gold, about 0.45% by weight copper, about 1.55% by weight zinc, about 0.1% by weight tin, about 0.85% by weight indium, about 0.05% by weight silicon, about 0.25% by weight gallium, and about 0.25% by weight cobalt.

### Claim 4

An alloy composition consisting essentially of about 95% by weight silver, about 0.5% by weight palladium, about 0.5% by weight platinum, about 0.5% by weight gold, about 0.45% by weight copper, about 1.55% by weight zinc, about 0.1% by weight tin, about 0.85% by weight indium, about 0.05% by weight silicon, about 0.25% by weight gallium, about 0.2% by weight cobalt, and about 0.05% by weight ruthenium.

### Claim 5 (depends on 2)

The alloy composition of claim 2, wherein the tarnish behavior index of the alloy with respect to 10K gold alloy is greater than or equal to about 1.4.

### Claim 6 (depends on 2)

The alloy composition of claim 2, wherein the tarnish behavior index of the alloy with respect to 10K gold alloy is between about 1.2 to 1.6.

### Claim 7

An alloy composition consisting essentially of about 92%-97% by weight silver, about 0.25%-1% by weight palladium, 0%-0.5% by weight platinum, about 0%-0.5% by weight gold, about 0.4%-0.45% by weight copper, about 1.15%-2.75% by weight zinc, about 0.1%-0.35% by weight tin, about 0.85%-1% by weight indium, about 0.05% by weight silicon, about 0.25%-0.5% by weight germanium, about 0.2%-0.25% by weight gallium, about 0.2%-0.25% by weight cobalt, and about 0-0.05% ruthenium.