Gold/silver alloys
United States Patent 3925066
A tarnish resistant Au/Ag alloy of low gold content exhibiting properties desired in jewelry manufacture consisting essentially of about 25 to 30 percent, by weight, gold, about 45 to 57 percent, by weight, silver, about 18 to 25 percent, by weight, of a metal selected from the group consisting of copper, nickel and mixtures thereof and 0 to about 5 percent by weight zinc.
US Patent References:
/1090939.html
Newton - March 1914 - 1090939
Manufacture of gold alloys
Loebich - October 1940 - 2216495
METAL ALLOY COMPOSITION
Nielsen et al. - January 1969 - 3424577
TARNISH RESISTANT ALLOY
Tuccillo et al. - October 1973 - 3767391
/1090939.html
Newton - March 1914 - 1090939
Manufacture of gold alloys
Loebich - October 1940 - 2216495
METAL ALLOY COMPOSITION
Nielsen et al. - January 1969 - 3424577
TARNISH RESISTANT ALLOY
Tuccillo et al. - October 1973 - 3767391
Inventors:
Kohrn, Edward Louis (Severna Park, MD)
Globus, Seymour (Bel Air, MD)
Globus, Seymour (Bel Air, MD)
Application Number:
05/480890
Publication Date:
12/09/1975
Filing Date:
06/19/1974
View Patent Images:
Export Citation:
Primary Class:
Other Classes:
420/587
International Classes:
C22C5/06; C22C5/06
Field of Search:
75/173R,173C,134C,134F,165
Primary Examiner:
Lovell C.
Assistant Examiner:
Weise E. L.
Attorney, Agent or Firm:
Larson, Taylor And Hinds
Claims:
It is claimed
1. A metal alloy consisting essentially of about 25 to 30 percent, by weight, gold, about 45 to 57 percent, by weight, silver, about 18 to 25 percent, by weight, of copper and 0 to about 5 percent by weight zinc.
2. A metal alloy consisting essentially of about 25 to 30 percent, by weight, gold, about 45 to 57 percent, by weight, silver, about 18 to 25 percent, by weight, of copper.
3. A metal alloy consisting essentially of about 25 to 30 percent, by weight, gold, about 45 to 57 percent, by weight, silver, about 18 to 20 percent by weight copper and about 1 to 3.5 percent, by weight, zinc.
4. An article of jewelry formed of the alloy of claim 1.
5. An article of jewelry formed of the alloy of claim 3.
1. A metal alloy consisting essentially of about 25 to 30 percent, by weight, gold, about 45 to 57 percent, by weight, silver, about 18 to 25 percent, by weight, of copper and 0 to about 5 percent by weight zinc.
2. A metal alloy consisting essentially of about 25 to 30 percent, by weight, gold, about 45 to 57 percent, by weight, silver, about 18 to 25 percent, by weight, of copper.
3. A metal alloy consisting essentially of about 25 to 30 percent, by weight, gold, about 45 to 57 percent, by weight, silver, about 18 to 20 percent by weight copper and about 1 to 3.5 percent, by weight, zinc.
4. An article of jewelry formed of the alloy of claim 1.
5. An article of jewelry formed of the alloy of claim 3.
Description:
BACKGROUND OF THE INVENTION
This invention relates to improvements in gold base alloys. More particularly the present invention is directed to low gold alloys possessing the properties desired in the manufacture of articles of jewelry.
Gold, per se, being a relatively solt metal is unsuitable for the manufacture of jewelry articles and must be alloyed with other metals so as to acquire the properties that make it serviceable for jewelry purposes. The most desirable properties for jewelry purposes in gold base alloys are castability, workability, tarnish resistance, luster and color. To achieve these properties it is generally necessary for the gold content of the alloys to be at least 41.65% by weight (i.e., at least 10 karat). It is well recognized that gold base alloys containing levels of gold lower than about 41.65% exhibit low tarnish resistance and quite often poor castability and workability. These drawbacks which characterize low gold alloys are particularly true of the gold/silver alloys of the prior art.
Attempts have been made to overcome this problem of poor tarnish resistance in below 10 karat gold/silver alloys by the inclusion in such alloys of minor amounts of other metals. Unfortunately these efforts have not been without their shortcomings for while tarnish resistance may be improved by such additions, one or more of the other desired properties, i.e. workability, castability including porosity, luster and color are invariably adversely effected.
OBJECTS OF THE INVENTION
One object of the present invention therefore is to provide a low gold alloy which possesses all the desired properties for jewelry manufacture.
Thus, it is an object of the invention to provide a low gold base alloy that can be worked, cast, molded, engraved, soldered and stamped using existing techniques with normal jewelry equipment.
It is also an object of the invention to provide a low gold alloy which is of sufficient hardness to take a normal jewelry finish either bright or textured as desired.
Yet another object of the invention is to provide a low gold base alloy of excellent color and luster.
A further object of the invention is to provide a low base alloy which in addition to possessing the aforementioned properties manifests a high tarnish resistance under normal usage.
Lastly, it is an object of the invention to provide at substantially reduced cost a low gold alloy which is a substitute for and which possesses all the beneficial properties of 10-14 karat gold base alloys.
SUMMARY OF THE INVENTION
These and other objects of the invention are obtained by a metal alloy consisting essentially of about 25 to 30 percent, preferably 27 to 29 percent, by weight, gold; about 45 to 57 percent, preferably 47 to 55 percent, by weight, silver; about 18 to 25 percent, preferably about 18 to 23 percent by weight of a metal selected from the group consisting of copper, nickel and mixtures thereof and 0 to about 5 percent, preferably about 1 to 3.5 percent by weight zinc.
DETAILED DESCRIPTION
The color of the alloys of the invention are either yellow or white depending upon whether or not nickel is present. In the absence of nickel the color of the alloy is yellow and in the presence of nickel the color of the alloy is white. When nickel is employed and a white alloy is desired the weight ratio of copper to nickel is about 2 to 3:1.
Illustrative of preferred yellow alloys are those consisting essentially of about 25 to 30 percent by weight, gold, about 45 to 57 percent by weight, silver, about 18 to 20 percent by weight, copper and about 1 to 3.5 percent by weight, zinc.
Preferred white alloys consist essentially of about 25 to 30 percent by weight, gold, about 45 to 47 percent by weight, silver, about 18 to 25 percent by weight of a mixture of copper and nickel wherein the weight ratio of copper to nickel is about 2 to 3:1 and about 2 to 3 percent by weight zinc.
The process of manufacturing the alloys of the invention does not differ from the standard practice in the manufacture of alloys of precious metals. The alloys may be prepared by simply weighing out the proper proportions of the constituents, placing them in a refractory crucible and subjecting the mixture to a heat sufficient to melt the materials. Care should be taken, however, to insure uniform alloying and mixing of the constituents.
A more convenient method for preparing alloys of the invention comprises alloying in equal proportions either 14 karat yellow gold or 14 karat white gold with sterling silver. The composition of 14 karat yellow gold generally is as follows: 56.25% Au, 30.7-32.8% Cu, 4.2-10.5% Ag and 2-7% Zn. 14 karat white gold on the other hand is ordinarily composed of 56.25% Au, 24.6% Cu, 12.8% Ni and 5.0% Zn. Sterling silver is constituted of 92.5% Ag and 7.5% Cu. Thus, the constituencies of these materials is such that 50/50 blends of either the white or yellow 14 karat gold and sterling silver provides novel low gold alloys of the invention.
The following example is included to further illustrate the present invention.
EXAMPLE
A 50/50 blend of 14 karat yellow gold and sterling silver were weighed and charged together into a refractory crucible wherein they were heated to a temperature of 1600°F with a gas torch until completely melted. The melt was stirred with a graphite rod immediately prior to casting and the alloy melt was then cast in air into a standard investment mold in the form of a ring. Upon cooling the alloy casting was removed and found to be sound with good surface fidelity and without unsightly porosity.
The head of the ring was subsequently mechanically worked, chased and burnished. All of these operations were completed with the same ease and pleasant results that are obtained with 10-14 karat gold alloys.
The finished ring was worn continuously for three months in a city environment without tarnish and without loss of form, color, luster, or polish.
A similar article of jewelry is obtained possessing like properties by substituting 14 karat white gold for the 14 karat yellow gold.
While the features of this invention have been disclosed with reference to the specific embodiments described therein, it is to be understood that various modifications may be made in the details of the manufacture without departing from the scope of this invention as defined in the appended claims.
This invention relates to improvements in gold base alloys. More particularly the present invention is directed to low gold alloys possessing the properties desired in the manufacture of articles of jewelry.
Gold, per se, being a relatively solt metal is unsuitable for the manufacture of jewelry articles and must be alloyed with other metals so as to acquire the properties that make it serviceable for jewelry purposes. The most desirable properties for jewelry purposes in gold base alloys are castability, workability, tarnish resistance, luster and color. To achieve these properties it is generally necessary for the gold content of the alloys to be at least 41.65% by weight (i.e., at least 10 karat). It is well recognized that gold base alloys containing levels of gold lower than about 41.65% exhibit low tarnish resistance and quite often poor castability and workability. These drawbacks which characterize low gold alloys are particularly true of the gold/silver alloys of the prior art.
Attempts have been made to overcome this problem of poor tarnish resistance in below 10 karat gold/silver alloys by the inclusion in such alloys of minor amounts of other metals. Unfortunately these efforts have not been without their shortcomings for while tarnish resistance may be improved by such additions, one or more of the other desired properties, i.e. workability, castability including porosity, luster and color are invariably adversely effected.
OBJECTS OF THE INVENTION
One object of the present invention therefore is to provide a low gold alloy which possesses all the desired properties for jewelry manufacture.
Thus, it is an object of the invention to provide a low gold base alloy that can be worked, cast, molded, engraved, soldered and stamped using existing techniques with normal jewelry equipment.
It is also an object of the invention to provide a low gold alloy which is of sufficient hardness to take a normal jewelry finish either bright or textured as desired.
Yet another object of the invention is to provide a low gold base alloy of excellent color and luster.
A further object of the invention is to provide a low base alloy which in addition to possessing the aforementioned properties manifests a high tarnish resistance under normal usage.
Lastly, it is an object of the invention to provide at substantially reduced cost a low gold alloy which is a substitute for and which possesses all the beneficial properties of 10-14 karat gold base alloys.
SUMMARY OF THE INVENTION
These and other objects of the invention are obtained by a metal alloy consisting essentially of about 25 to 30 percent, preferably 27 to 29 percent, by weight, gold; about 45 to 57 percent, preferably 47 to 55 percent, by weight, silver; about 18 to 25 percent, preferably about 18 to 23 percent by weight of a metal selected from the group consisting of copper, nickel and mixtures thereof and 0 to about 5 percent, preferably about 1 to 3.5 percent by weight zinc.
DETAILED DESCRIPTION
The color of the alloys of the invention are either yellow or white depending upon whether or not nickel is present. In the absence of nickel the color of the alloy is yellow and in the presence of nickel the color of the alloy is white. When nickel is employed and a white alloy is desired the weight ratio of copper to nickel is about 2 to 3:1.
Illustrative of preferred yellow alloys are those consisting essentially of about 25 to 30 percent by weight, gold, about 45 to 57 percent by weight, silver, about 18 to 20 percent by weight, copper and about 1 to 3.5 percent by weight, zinc.
Preferred white alloys consist essentially of about 25 to 30 percent by weight, gold, about 45 to 47 percent by weight, silver, about 18 to 25 percent by weight of a mixture of copper and nickel wherein the weight ratio of copper to nickel is about 2 to 3:1 and about 2 to 3 percent by weight zinc.
The process of manufacturing the alloys of the invention does not differ from the standard practice in the manufacture of alloys of precious metals. The alloys may be prepared by simply weighing out the proper proportions of the constituents, placing them in a refractory crucible and subjecting the mixture to a heat sufficient to melt the materials. Care should be taken, however, to insure uniform alloying and mixing of the constituents.
A more convenient method for preparing alloys of the invention comprises alloying in equal proportions either 14 karat yellow gold or 14 karat white gold with sterling silver. The composition of 14 karat yellow gold generally is as follows: 56.25% Au, 30.7-32.8% Cu, 4.2-10.5% Ag and 2-7% Zn. 14 karat white gold on the other hand is ordinarily composed of 56.25% Au, 24.6% Cu, 12.8% Ni and 5.0% Zn. Sterling silver is constituted of 92.5% Ag and 7.5% Cu. Thus, the constituencies of these materials is such that 50/50 blends of either the white or yellow 14 karat gold and sterling silver provides novel low gold alloys of the invention.
The following example is included to further illustrate the present invention.
EXAMPLE
A 50/50 blend of 14 karat yellow gold and sterling silver were weighed and charged together into a refractory crucible wherein they were heated to a temperature of 1600°F with a gas torch until completely melted. The melt was stirred with a graphite rod immediately prior to casting and the alloy melt was then cast in air into a standard investment mold in the form of a ring. Upon cooling the alloy casting was removed and found to be sound with good surface fidelity and without unsightly porosity.
The head of the ring was subsequently mechanically worked, chased and burnished. All of these operations were completed with the same ease and pleasant results that are obtained with 10-14 karat gold alloys.
The finished ring was worn continuously for three months in a city environment without tarnish and without loss of form, color, luster, or polish.
A similar article of jewelry is obtained possessing like properties by substituting 14 karat white gold for the 14 karat yellow gold.
While the features of this invention have been disclosed with reference to the specific embodiments described therein, it is to be understood that various modifications may be made in the details of the manufacture without departing from the scope of this invention as defined in the appended claims.