US3606766A

US3606766A - Gold finger article composed of compressed and sintered fine gold powder and a refractory oxide

Info

Publication number: US3606766A
Application number: US836735A
Authority: US
Inventors: James S Hill
Original assignee: Engelhard Minerals and Chemicals Corp
Current assignee: BASF Catalysts LLC; Engelhard Minerals and Chemicals Corp
Priority date: 1969-06-26
Filing date: 1969-06-26
Publication date: 1971-09-21
Anticipated expiration: 1988-09-21

Abstract

A GOLD FINGER RING COMPOSED OF COMPRESSED AND SINTERED FINE GOLD POWDER HAVING UNIFORMLY DISPERSED THERETHROUGH FROM 0.03% TO 0.2% OF REFRACTORY OXIDE PARTICLES HAVING A SIZE BETWEEN 0.5 AND 5 MICRONS.

Description

Sept. 21, 1971 GOLD FINGER ARTICLE COMP N'I'ERED S. HILL OSED 0F COMPRESSED AND SI FINE GOLD POWDER AND A REFRACTORY OXIDE Filed June 26, 1969 INVIL'NTOR.

JAMES S. H/LL United States Patent 7 ABSTRACT OF THE DISCLOSURE A gold finger ring composed of compressed and sintered fine gold powder having uniformly dispersed therethrough from 0.03% to 0.2% of refractory oxide particles having a size between 0.5 and microns.

BACKGROUND OF THE INVENTION Gold finger rings are usually composed of cast gold alloys, e.g., 14 carat gold, which contain metal alloying components such as copper, silver and zinc. It is known that because of the presence of these metal alloying components the skin of the human finger in contact with the rings is sometimes subject to a reaction which may cause some peeling of the skin or a greenish discoloration of the skin.

This would not occur if the ring was composed of 24 carat gold, i.e. pure gold, but the 24 carat gold is too soft and the ring would not retain its shape and therefore, necessitates the addition of alloying metal components to harden the ring.

It is herein contemplated to provide a gold finger ring of substatnially 24 carat gold (fine gold) which will overcome the above-mentioned disadvantages.

SUMMARY OF THE INVENTION In accordance with the invention, there is provided a gold finger ring composed essentially of fine gold powder (24 carat) in compressed and sintered condition having uniformly dispersed therethrough from 0.03% to 0.2% of refractory oxide particles having a size between 0.5 and 5 microns. The oxides within this size range are preferably obtained by the decomposition of a soluble salt of the metal forming the refractory oxide and effectively hardening the fine gold, when uniformly dispersed therethrough, to a hardness at least that of 18 carat gold while providing for a ductility sufficient to make the ring sizable from about to 1 size larger than the originally formed ring.

DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates an elevational side view of the finger ring according to the invention,

FIG. 2 illustrates a cross-sectional view along lines 22 of FIG. 1, and

FIG. 3 illustrates a modification of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1 and 2 of the drawings, the finger ring 1 is composed of compressed and sintered fine gold powder having uniformly dispersed therethrough from 0.03% to 0.2%, preferably from 0.1% to 0.15%, of refractory metal oxide particles 2 having a particle size between 0.5 and 5 microns. The refractory metal oxides are, for example, A1 0 ZrO ThO Y O SiO or MgO The following is an example method of manufacture of the ring:

3,606,766 Patented Sept. 21, 1971 "ice EXAMPLE A 2" by 2" mold assembly was lubricated with a solution of stearic acid in trichloroethylene and charged with 6.0 troy ounces of fine gold powder. The gold powder was pressed in the mold under a load of 12 tons gauge pressure to yield a 0.291" thick bar. The gold bar was weighed and placed in a vacuum chamber where the air in the voids in the compressed bar was evacuated. The chamber was subsequently flooded with a 40% solution of Al(NO while the chamber was under vacuum condition. The bar was removed, oven dried for 16 hours at 250 C., and cooled in a dessicator. The cooled bar was weighed and found to contain 0.10% A1 0 Next, the bar was sintered in air for 2 hours at 900 C., coined at 20 tons gauge pressure and post sintered in air for 2 hours at 900 C. The gold workpiece was rolled to a 0.123" thick sheet with annealing between each rolling operation for /2 hour at 750 C.-800 C. Gold rings which retain their shape and have excellent wear characteristics were punched from the gold sheet. The outer surface of the rings were provided with a rounded contour by machining.

In accordance with the above example, three gold bars were each impregnated with a solution containing 20%, 25% and 30% zirconium nitrate, respectively, and provided zirconia contents of 0.10%, 0.15% and 0.27%, respectively. The thre gold bars were compressed, sintered and rolled into workpieces similarly as in Example 1 and likewise similarly formed into gold rings.

It was also found that another gold bar, similarly to Example 1, was impregnated with a 10% solution of thorium nitrate and yielded about 0.2% of ThO Wear tests were conducted on a gold sheet sample material from which the rings of the invention were fabricated which clearly show that the dispersion strengthened gold has better wear characteristics than either fine gold or 18K yellow gold. These wear tests were conducted on a Taber Abraser, Model 174, under gram load with green test wheels which were dressed before each test. The sheet sample size was 1" X 2" x 20 mil thickness. The observed weight loss given in the table below represents the average of three tests.

TABLE I.WEAR CHARACTERISTICS OF GOLD SAMPLES Weight loss in grams From these tests it can be seen that strengthened gold with as little as .075% ThO for example, gives a composite material with better wear characteristics than fine gold alone; and, if fine gold is strengthened with up to 0.2% ThO the year characteristics even surpass 18K gold.

Regarding FIG. 3, the ring, after forming and machining, can be provided with a flash coating 3 of gold for the purpose of being capable of a higher polish.

While the above description relates specifically to gold finger rings, other articles of jewelry which are worn in contact with the human skin are also contemplates, such as earrings, neck chains and pendants.

I claim:

1. A gold finger ring consisting of compressed and sintered 24 carat fine gold powder having uniformly dispersed therethrough from 0.03% to 0.2% by weight of refractory oxide particles having a particle size between 0.5 and 5 microns.

2. A gold finger ring according to claim 1, wherein the fine fold powder has uniformly dispersed therethrough from 0.1% to 0.15 by weight of the refractory oxide.

3. A gold finger ring according to claim 1, wherein the refractory oxide is A1 0 ZrO ThO Y O SiO or MgO.

4. A gold finger ring consisting of compressed and sintered 24 carat fine gold powder having uniformly dispersed therethrough from 0.03% to 0.2% by weight of refractory oxide particles having a particle size between 0.5 and 5 microns, said ring being coated with a gold flash coating.

5. An article of jewelry comprising a metal body for contact with the human skin, said metal body consisting of compressed and sintered 24 carat fine gold powder having uniformly dispersed therethrough from 0.03% to 0.2% by weight of refractory oxide particles having a particle size between 0.5 and 5 microns.

References Cited UNITED STATES PATENTS 3,139,682 7/1964 Grant 29182.5 3,150,443 9/1964 Alexander ct a1 29182.5 3,218,135 11/1965 Alexander et a1. 29-182.5

10 F. BARRY SHAY, Primary Examiner US. Cl. X.R.