US1557431A - Gold alloy and method of making the same - Google Patents

Description

Patented Oct 13 1925.

UNITED STATES No Drawing.

To all whom it may concern: Be it known that I, VICTOR D. DAVIGNON, a citizen of the United States, and a resident of Attleboro, in the county of Bristol and State of Massachusetts, have invented an,

Improvement in Gold Alloys and Methods of Making the Same, of which the following description, in connection with the accompanying drawings, is a specification, like characters on the drawings representing like parts.

This application-is a continuation in part of my pending application, Serial Number 47,367, filed July 31, 1925.

My invention relates to alloys of precious metals, and particularly to alloys of gold containing aluminum, and to the process of making the same. 7

The gold alloy now commonly used in the arts has as its characteristic constituents gold and copper with appropriate base metals other than copper to give it the requisite' -hardness, color and other desired physis cal'characteristics'. This gold-copper alloy,

while otherwise satisfactory, has the disadvantage of possessing a relatively high spe:

cific gravity; and it 1s among the objects of my invention to produce a gold alloy of much lower specific gravity but with the same gold ratio, thereby enabling me to fab ricate articles of given size or volume with a smaller gold content that with alloys heretofore known to me.

In the arts gold is rated according to its carat, that is to say, 14 carat gold, for example, contains 14 parts by weight of gold and 10 parts by weight of base metal, a total of 24 parts, and any gold alloy which contains 14 parts by weight of gold for each 24 parts by weight of alloy will be rated as 14 carat gold regardless of the s ecific'grav- .ity of the alloy. Accordingly, by reducing the specific gravity of the alloy by my improved method, I obtain an alloy which for a given carat and volume will have less,

weight, enabling articles of given volume made from it to berated at this given carat although in fact containing a smaller amount of gbld than if made of prior known alloys. For these reasons, as the cost of producing an alloy is largely determined by its gold content, articles of given volume made of gold of a given carat can be made at less expense with my improved alloy.

I have found that it is impossible to alloy gold with aluminum by prior methods of 1,557,431 PATENT" OFF I com) ALLOY AND mentor) or MARI-[HG g Y Application flied September 4, 1925-, Serial No. 54,499.

producing gold l a'lloys and obtain homogene- I ous product which is malleable and ductile enough to meetthe requirements of the goldsmith and which possesses the requisite characteristics for enabling articles to be desirable properties in the attempted aluminum alloy I believe is largely due to the presence of oxidized aluminum in the alloy.

As distinguished from the prior gold- .copper alloys,my improved alloy has as its distinguishing characteristics the presence of aluminum in amount sufficient materially to reduce the specific gravity of the alloy; the

alloy being malleable and ductile to a degree 'suflicient to meet the usual, requirementsgof the goldsmith; and the ingot when made-$3. my improved method being workable by usual goldsmiths 'p'rocewes, and being a substantially. homogeneous structure free from checks and blisters, thus permitting eflicient utilization of the alloy.

The desired degree of hardness and color or other physical characteristics are obtained by the introduction of other base metals as willhereinafter appear. l

As showing the efiectof the aluminum on the specific gravity of my improved alloy I may make a 14 carat gold alloy in the proportions of 14 parts by weight of gold, 6 parts by weight of copper, 3 parts by weight ofzinc, and 1 part by weight of alluminum. The'efiect of the aluminum on the specific gravity of the alloy can be appreciated when it is observed that in this example the volume of the aluminum employed-is slightly greater than 50% of the volume of the gold due to the relatively low specific gravity of the aluminum compared to that of gold.

to, the metals entering into the alloy are placed in the crucible or other container in which they are melted, preferably in inverse order of their specific gravities, which is to say that the aluminum, for example, will be placed at the bottom of the crucible and the gold and other metals above it. The ciuci ble is then heated in a furnace to a temperature at which the metals become liquid, the mixture conveniently being stirred to mix the constituents which is facilitated by the fact that the metals of low specific gravity tend to rise through themetals of higher p specific gravity,

During the pouring operation, and prefer ably during a period immediately preceding the pouring operation, I efliect prevention of the action of'the air on the molten metals, for example, the crucible a suitable s flux which, when added; will melt and form a liquid layer at the of the molten metal and pass out of the crucible simultaneously with the stream of molten metal entering the mold, this example being particularly applicable in cases where the melting and pouring are efi'ected by use of the conventional t pes'of crucible and mold. Preferably the ux employed in this example consists of or contains a substance which will effectively eliminate from the alloy substantially all aluminum oxide I as well as the oxides of copper andof other my method I preferably which for s surface of iih chloride and sodium fluoride.

base metals such as zinc, nickel and silver,

mixture of the'two inthe proportionof 1 part, calcium chloride to- 2. parts potassium bifluoride. These substances I have found at the temperature of the molten metal will not substantially volatilize at the tempera.-

,-ture; maintained, and consequently will eifec tivel maintain a .seal on the molten metal in t e crucible and about the stream of molten metal being poured into the mold.

Intheabove example of the practice of crucible in the form 0 and. ourthe metal into the molds a flux as remained on the metal ina molten state for a short period, say about five minutes. Preferably the amount of flux will be suflicient to form on the metal in the crucible a la er of about One quarter of an inch in ess. When the metal is poured the,

thic flux which leaves the crucible with the stream of metal, owing to its low specific gravity, will form a layer or film about the stream of metal andwill'enter the mold with the metal, thus preventing action of the air on the metal. At the same time the flux efi'ects elimination of aluminum oxide which I explain it does by dissolving from the metal while the latter is'liquid, any oxv ide which may be formed or present, and

thus confining the oxide to the layer of slag in thecrucible and about the e ingot. In addition to calcium chlorideand potassium bifluoride I have also found as suitable for flux, cryolite, potassium chloride, sodium given Although in the example of fluxes ogen salts of alkaline earths, it is all are he by adding to the contents of v .alloy may consist 0i, about 58% gol :alununumand' 37 copper, in which ex-' add the flux to the 1 crystals or owder r the to be understood that I am not necessarily limited to fluxes "so characterized, but that other fluxes which will eliminate aluminum oxide and form'a liquid seal preventing aceess of airto the molten metal may beusecL.

In the above example of the practice of my method I'havefound that satisfactory results will be secured by employing sub 'stantiallypure virgin aluminum, as for example, the grade characterized by the trade as commercially pure, if substantially free from substances such as lead, phosphorus, bismuth and arsenic, deleteriously affecting physica characteristics of the alloy. I

Itwill be understood that in the above ex ample other base metals than those already.

mentioned may be added for imparting special properties to the alloy, and that the content of aluminum may beivaried relatively to the gold content to produce alloys of difierent carat and difl'erent specific gravity.

the malleability' or other desired c In practice, the gold may run from 25% .to

% and the aluminum content from 1% to 10% by weightof the alloy, the remaining base metal in the'usual case being wholly or largely copper except where-green gold (commonly an 18 caratproduct) is desired,

in which case the remaining base metal will be wholly or largely silve'r. As an example of a desirable 14 carat commercial alloy, the

ample desired, a portionof the copper maybe replaced by'other base metal or metals such as zmc,n ickel, silveryetc'. In

,. the claims by base metal rendering the alloy malleable and ductile I refer to such .metals as-copper, silver, etci, commonly employed as constituents of gold alloys.

As an example of the practice, of my lGt method but without limitation thereto I may.

take a graphite crucible of the generally frusto-conical shape commonly employed in the art, say the one known to the trade as a #8-black lead 7 crucible, which is about four inches in. diameter at the top and about seven andione-half' inches high, and place in the bottom of the crucible scraps of sheet aluminum about the size of a dime in amountequal to 5 troy ounces. Upon the aluminum I'now place a mixture of 5833 troy ounces of gold in bar form and 36.27

troy ounces of copper in the form of small ing of a mixture of potassium bifiuoride andcalcium chloride crystals, heretofore de-' on the molten metal. About five minutes after the flux has melted the crucible isremoved from the'furnace and the contents of the crucible are poured into the mold in I a steady stream of aboutthe thickness of a lead pencil say five-sixteenths of an inch.

The mold for this purpose conveniently may be of iron with a mold chamber, in cross-section a rectangle of about A,, by 2 inches, and about 10 inches long. The mold preferably is positioned to place the long axis of the mold chamber at about degrees to the horizontal and with the sides of the mold chamber of greatest width in vertical planes.

The metal is now allowed to solidify, after which the mold is opened and the ingot removed. After the ingot has cooled it. is placed in a pickle consisting of dilute sulphuric acid in the proportion of 1 part acid to 20 parts water and allowed to remain in the pickle until the slag or scale covering its exterior is removed or "softened sufiiciently to permit removal by subsequent washing, after which the ingot is removed and washed and then may be subjected to the rolling or other operations desired.v

Although I have described for purposes of illustration several specific compositions of my improved alloy and one particular way of practicin my method, it is to be understood that am not limited thereby to the particular method, constituents or proportions thereof, or to the particular apparatus described, but that within the S00 e 01E my invention widedeviations maye made therefrom without departingfrom the spirit of my invention.

I claim: l

and ductile gold-copper alloy having not less than about 25% by weight of gold and a material proportion ofcopper and containing at least 1% by weight of aluminum. 2. A- gold-copper alloy having not less than about 25% by weight of gold and a. material proportion of copper and contain-.

ing. at least 1% of aluminum, and being substantially free from oxidized aluminum. 3. A substantially homogeneous malleable and ductile gold-copper alloy having. not less than about 25% by weight of gold and a material proportion of copper and containing from 1 to 10% by weight of aluminum.

' loy's having 'a material proportion of coper and containing d fr an om 1 to v said container into a mold. 4. Maleable and ductile gold-copper al-.

from about 25% to 85%.

having from about 25% to 85% by weight of gold and from 1% to 10% by weight of aluminum, and containing, base metal rendering the alloy malleable and ductile.

6. A malleable and ductile alloy containing by weight, about 58%. of gold, 5% of aluminum an'd37% of copper.

7. A malleable and ductile alloy contain ing by weight .about 58% of gold, 5% of aluminum and ;lf(% of base metal includ-' ing a material amount of copper.

8. That process of making a gold alloy containing a material proportion of aluminum which comprises melting the metals in a container, and effecting sealing oi the molten metal from the action of the atmosphere while pouring the metal into a mold.

9. That process of making a gold alloy a container, and efi'ecting sealing of the molten metal from the action of the atmosphere while pouring themetal into a mold by effecting on the stream of molten metal being poured from the container into the mold a coating of flux capable of eliminating aluminum oxide. 4

10. That processof making a gold alloy containing a material proportion of aluminum, which comprises melting. the metals in acontainer and adding to the molten metals a flux having a halogen salt of an alkaline earth;

11. That process of making a gold alloy containing a material proportion of alumi num, which comprises melting the metals in a container and adding to the molten metals a flux which will eliminate aluminum oxide.

12. That process of making a gold alloy containinga' material proportion of aluminum, which comprises melting the metals in acontainer and adding to the molten metals V a flux comprising potassium bifluoride. 1. A substantially homogeneous malleable f 13. That process of making a gold alloy containing a material proportion of aluminum, which comprises melting the metals in a container and adding to the molten metals a flux containing calcium chloride and po' tassium bifluoride."

14. That process of making a gold alloy containing a material proportion of alumimetal from the atmosphere, and pouring the molten'm'etal and flux simultaneously from 15. That process'of making argold alloy containing a. mate'ral proportion, of alums num, which com rises melting the metals in i a container, addingto the metals 8. flux containing a fusible halogen salt of an'alkaline earth in amount suflici'entfto'form a liquid layer on the molten metal efiective'to seal said metal from the atmosphere, and pouring .the molten metal and flux simultaneously from said container'into a mold.

16. That process of making a gold alloy containing a material proportion of aluminum, utilizing a cruicble, a furnace" and a mold, which comprises placing the-metals in solid state in said crucible with the aluminum below the heavier metals, heating the crucible to render said metals liquid,

adding to said crucible after liquefaction of the metals a fusible flux containing metallic salts capable of eliminating aluminum oxide,

' said flux being in amount suflicient to form In testimony whereof, I have signed .my 20 name to this specification.

VICTOR D. DAVIGNON.