Silver palladium alloy

by: Davitz, Daniel;

A silver colored metal alloy having improved tarnish resistance is disclosed, which is intended primarily for solid sterling jewelry and utensils and may also be used in silver plating, and does not easily tarnish and corrode. The alloy consists essentially of 80% to 92.5% silver, 4% to 9% palladium, 0% to 10% copper and 0.5% to 1% indium or zinc.


1. Field of the Invention

The present invention relates generally to silver alloys, and in particular to a silver alloy having improved tarnish resistance. Sterling silver ordinarily alloy contains 92.5% silver, and 7.5% copper. Preferably this alloy must be moldable and castable with low surface tension to conform to intricate molds. In addition, the alloy should provide a material which does not easily tarnish and corrode, especially when used for jewelry.

2. Prior Art

Sterling silvery jewelry and utensils are valued because of their intrinsic worth and the silver color of the metal. However, a problem has been found in using sterling silver because of its tendency to tarnish and corrode.

Many attempts have been made to improve the tarnish and corrosion resistance of sterling silver and to improve the casting qualities of sterling silver.


Accordingly, an object of the present invention is to provide a more corrosion resistant and tarnish resistant silver alloy with better working properties then sterling silver.

For example, an alloy called premium has been provided in the past which comprises 74% A.sub.g, 25% Pd 1% ZN. Another alloy previously sold is 66% A.sub.g, 23% Pd, 10% Cu and 1% ZN. However, these alloys have been found to be more expensive and thus have not found substantial commercial use.

Accordingly, an object of the present invention is a silver alloy having chemical and physical properties suitable for use in jewelry.

An additional object of the present invention is to provide a silver color alloy, that will have better tarnish, an corrosion resistance with excellent working properties and still have a low cost alloy.

Other objects of the present invention and advantages accruing therefrom will be apparent to one skilled in the art in the following detailed description. all percentages referred to ar percent by weight based on the total weight of the material or mixture.


In accordance with the present invention, a silver colored metal alloy is disclosed which is exceptionally tarnish resistant and corrosion resistant and comprises the following ingredients: 80% to 92.5% silver, 4% to 9% palladium, 10% to 0% copper and 1% to 0.5% indium or zinc.

To be considered in the sterling family, an alloy must have at least 92.5% silver. Usually the remainder of the alloy sterling silver is copper and sometimes zinc. In the present invention, we have replaced most or all the copper with palladium to enhance tarnish resistance and corrosion resistance. We find that this not only gives us a more color stable alloy then sterling silver, but also due to the addition of indium and palladium, the working and casting properties are much improved and the alloy is not brittle. The ratio of silver preferred due to cost and to be considered like sterling silver is 92.5% silver, 5% palladium, 2% copper and 0.5% indium or zinc.

Palladium in this alloy gives the alloy a much greater tarnish and corrosion resistance.

The use of copper enhances the working properties when in conjunction with the pal adium and silver.

The specific gravity of this alloy is 10.27 gms/cc plus or minus, 0.5. Other physical properties are as follows:

    Low Hardness         105 BRINELL
    High Hardness        165 BRINELL
    Elongation           15 to 26%

Specifically, the preferred alloy formula in accordance with this invention is:

    Palladium        5%
    Silver            92.5%
    Copper           2%
    Indium (or zinc)   .5%

While the specific alloy described is intended primarily for solid sterling jewelry and utensils, it may also be used in silver plating using conventional silver plating techniques. As a result, a highly tarnish resistant silver plate is provided at a nominal increase in cost.

The above described alloys have a casting temperature of approximately 1850 degrees Fahrenheit plus or minus 50 degrees. The melting temperature of the alloys is approximately 1750 degrees Fahrenheit plus or minus 50 degrees.

Conventional chlorine and/or ammonia testing of this alloy exhibits n tarnishing or corrosion after exposure for 10 days. While this invention has been described with reference to a preferred content and formula, it will be understood by those skilled in the art that various changes may be made and equivalents substituted for elements described herein without departing from the scope of the invention. In addition, many modifications may be made to adapt to a particular situation or material to the teachings of the invention without departing from the scope thereof. Therefore it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.

Window sash

Drain-extended MOS ESD protection structure

Method of fabricating electronic circuits

Low-noise frequency synthesizer

Facial sun block mask

Somatostatin receptors

Compartmentalized basket truck

Metering apparatus

Vertical storage toolbox

Automated nut-cracking apparatus and method

Golf club stand device

Aerobic exercise device

Liquid container

Gravity particle separator

Electronic voting machine

Layered film and packaging material

Variable delivery compressor

Dual chamber water filter

Flash jet coolant circulation system

Multi-channel optical transmission system

Flexible chain conveyor

Lock for sliding doors

Device in clearing saws

Modular station platform construction kit

Passive lavatory cleanser dispensing system

Shutter time control circuit

Pulse width modulation operation circuit

Inter-LAN connection method using ISDN

Plastic orientation measurement instrument

Wheelchair motorizing apparatus

Brake pressure control valve

Impact-resisting composites

Facsimile compression for transmission

Collapsible wheelbarrow

Preparation of star polymers

Paint toning machine

Automatic trimming machine

Process for decoking catalysts

Signal amplifier

Nitrogen detection

Master cylinder apparatus

Fuel dispensing nozzle

Perfusive chromatography

Golf putt training apparatus

Asymmetric wire rope isolator

Magnetic blanket for horses

Multiple pouch bagging apparatus

Cotton gin control

Power-generating control apparatus for vehicle

Environmentally stable monolithic Mach-Zehnder device

Catalyst patterning for nanowire devices

Moisture-curing polyamides

Polishing apparatus

Arrangement for moving an object

Digital character display

Glass compositions

Water filtration assembly

Portable foldable splint

Control means for ground hydrants

Internal combustion engine

Stacker bundler shuttle system

Non-aqueous electrochemical cell

Manual floor sweeper

Motor control system

Article transferring apparatus

Output regulator

Optical device, system and method

Process for concentrating fluids

High temperature diesel deposit tester

Towable "V" rake agricultural machine

Developer powder supply cartridge

Weapon stabilization system

Modular nuclear fuel assembly design

4-Aminoaliphatic-2,3,5,6-[dibenzobicyclo[5.1.0]octanes] and salts thereof

Electromechanical preparation of photoengraving cylinders

Compact and robust spectrograph

Direct conversion receiver per-selection

Outdoor enclosure with heated desiccant

Wearable display

Solar thermal propulsion unit

Elongated flexible detonating device

Motor vehicle wiper

Hollow fiber separatory device

Method of preparing ferroelectric ceramics

Cervical traction device

Fermentation process

Light distribution device

Seal press

Electrical coupling unit for electrosurgery

Motor vehicle gearbox

Cover connecting mechanism

Floating inlet tube

Incontinence electrode apparatus

Security and deployment assembly

Dual-wavelength x-ray monochromator


Clear impact-resistant syndiotactic polypropylene

Antimicrobial cationic peptides

Intraocular lens

Endoscope signal level control

Pest bait station

Flash memory device

Front vehicle body structure

Aqueous coating composition

Support for a torch

Surface modifier composition

Electromechanical toy

Unitary key holder

Tissue anchoring system and method

Fuel system for multicylinder engines

Plain bearing

Start-up circuit for voltage regulators