US3748712A - Tarnish resistant plating for silver articles - Google Patents

Tarnish resistant plating for silver articles Download PDF

Info

Publication number
US3748712A
US3748712A US00129595A US3748712DA US3748712A US 3748712 A US3748712 A US 3748712A US 00129595 A US00129595 A US 00129595A US 3748712D A US3748712D A US 3748712DA US 3748712 A US3748712 A US 3748712A
Authority
US
United States
Prior art keywords
silver
plating
rhodium
platinum
microinches
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US00129595A
Inventor
K Karawin
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
NEW FRANKLIN MINT
Warner Communications LLC
Original Assignee
FRANKLIN MINT CORP
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by FRANKLIN MINT CORP filed Critical FRANKLIN MINT CORP
Application granted granted Critical
Publication of US3748712A publication Critical patent/US3748712A/en
Assigned to FIRST NATIONAL BANK OF BOSTON, THE, reassignment FIRST NATIONAL BANK OF BOSTON, THE, SECURITY INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: FRANKLIN MINT COMPANY
Assigned to WARNER COMMUNICATIONS INC. reassignment WARNER COMMUNICATIONS INC. MERGER (SEE DOCUMENT FOR DETAILS). Assignors: FRANKLIN MINT CORPORATION A CORP OF DE
Assigned to FRANKLIN MINT CORPORATION reassignment FRANKLIN MINT CORPORATION CHANGE OF NAME (SEE DOCUMENT FOR DETAILS). Assignors: WCI-MINT CORP.
Assigned to WCI-MINT CORP. reassignment WCI-MINT CORP. ASSIGNS NUNC PR TUNC AS OF MARCH 2, 1981 THE ENTIRE INTEREST IN SAID PATENTS Assignors: WARNER COMMUNICATIONS, INC.
Assigned to NEW FRANKLIN MINT reassignment NEW FRANKLIN MINT ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: FRANKLIN MINT CORPORATION
Assigned to FIRST NATIONAL BANK OF BOSTON, THE AS COLLATERAL AGENT reassignment FIRST NATIONAL BANK OF BOSTON, THE AS COLLATERAL AGENT AMENDED SECURITY AGREEMENT (SEE RECORD FOR DETAILS) Assignors: FIRST NATIONAL BANK OF BOSTON, THE, AS AGENT, FRANKLIN MINT COMPANY
Assigned to FIRST NATIONAL BANK OF BOSTON, THE, AS AGENT, FRANKLIN MINT COMPANY reassignment FIRST NATIONAL BANK OF BOSTON, THE, AS AGENT LICENSE (SEE DOCUMENT FOR DETAILS). Assignors: FIRST NATIONAL BANK OF BOSTON, THE, AS COLLATERAL AGENT
Assigned to FRANKLIN MINT COMPANY, DE GENERAL PARTNERSHIP COMPANY reassignment FRANKLIN MINT COMPANY, DE GENERAL PARTNERSHIP COMPANY RELEASED BY SECURED PARTY (SEE DOCUMENT FOR DETAILS). Assignors: FIRST NATIONAL BANK OF BOSTON, THE, AS COLLATERAL AGENT
Assigned to FRANKLIN MINT COMPANY, A DE GENERAL PARTNERSHIP COMPANY reassignment FRANKLIN MINT COMPANY, A DE GENERAL PARTNERSHIP COMPANY LICENSE (SEE DOCUMENT FOR DETAILS). Assignors: FIRST NATIONAL BANK OF BOSTON, THE, COLLATERAL AGENT
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Classifications

    • A—HUMAN NECESSITIES
    • A44—HABERDASHERY; JEWELLERY
    • A44C—PERSONAL ADORNMENTS, e.g. JEWELLERY; COINS
    • A44C3/00—Medals; Badges
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S428/00—Stock material or miscellaneous articles
    • Y10S428/922—Static electricity metal bleed-off metallic stock
    • Y10S428/923—Physical dimension
    • Y10S428/924—Composite
    • Y10S428/926—Thickness of individual layer specified
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S428/00—Stock material or miscellaneous articles
    • Y10S428/922—Static electricity metal bleed-off metallic stock
    • Y10S428/9265—Special properties
    • Y10S428/927—Decorative informative
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/12—All metal or with adjacent metals
    • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
    • Y10T428/12771—Transition metal-base component
    • Y10T428/12861—Group VIII or IB metal-base component
    • Y10T428/12889—Au-base component

Definitions

  • ABSTRACT Articles made of silver or silver alloys containing a high percentage of silver, and particularly silver medals and medallions may be rendered tarnish resistant while still possessing a color closely matched to the original article by plating with a rhodium-platinum alloy.
  • the alloy plating has a thickness of l to 50 microinches, and preferably 1 to 10 microinches, and comprises about 1 to 9 weight percent platinum, and preferably 3 to 5 weight percent platinum, with the remainder being rhodium. It is also necessary to provide the silver article with a flash plating of yellow gold prior to plating with the rhodium-platinum alloy in order to obtain the optimum color match.
  • the present invention relates to tarnish resistant silver articles and, more particularly, to tarnish resistant silver base medals and medallions containing about 80 to 100 weight percent of silver.
  • Silver and silver alloys particularly fine silver and sterling silver, have long been highly preferred for medals, medallions, jewelry, tableware and various objects of art. This preference is due to the high reflectivity and elegant appearancev which make silver particularly attractive.
  • a major disadvantage of sterling silver and other silver alloys has been the relative ease with which the silver articles tarnish.
  • tarnishing of silver objects has become increasingly severe in recent years.
  • the high concentration of air pollutants has resulted in more rapid and more extreme tarnishing.
  • Particularly harmful tarnishing agents include cigarette smoke and hydrogen sulfide (H 8) which is increasingly present in the atmosphere as a product of fuel oil combustion and various industrial processes.
  • silver base medals and other silver articles with a tarnish resistant plating having a thickness of about 1 to 50 microinches and consisting of a metal alloy of about 91 to 99 weight percent rhodium and about I to 9 weight percent platinum.
  • the silver base medal is also provided with a thin layer of yellow gold underlying the rhodium-platinum alloy. It is to be understood that whereever the terms silver base medal or silver article are used throughout this specification, medals or articles containing from about 80 to 100 weight percent of silver are intended.
  • the silver base medals to be plated contain about 80 to 100 weight percent silver, and preferably to weight percent silver, the remainder being any of a number of alloying metals.
  • the range of 90 to 100 weight percent silver encompasses both sterling silver (92.5 percent silver) and fine silver as well as other silver alloys.
  • the remaining percentage is usually copper, which is alloyed with the silver. However, other alloying metals may be used.
  • the tarnish resistant plating which is applied to the silver base medals comprises a metal alloy of about 91 to 99 weight percent rhodium and about 1 to 9 weight percent platinum.
  • a preferred alloy plating contains about 95 to 97 weight percent rhodium and about 3 to 5 weight percent platinum. It should be understood that the term alloy is intended to describe a codeposition of the rhodium and platinum, as opposed to separate depositions or platings of the two metals. Thus, a solidsolid solution of platinum in rhodium is obtained rather than two separate layers.
  • the codeposition or alloy plating may have a thickness of between about 1 and 50 microinches, and preferably l and 10 microinches.
  • a parituclarly preferred codeposition has a thickness of about 2 to 3 microinches.
  • the silver base medals first be provided with a yellow gold (pure gold) strike or flash plating.
  • the yellow gold flash plating should have a thickness of about I to 30 microinches, and preferably about 1 to 7 microinches.
  • a yellow gold strike or flash plating followed by a rhodium-platinum codeposition of about 2 to 3 microinches provides a tarnish resistant plating resulting in a particularly good color match for sterling silver medals.
  • the rhodium-platinum codeposition or alloy plating may be produced by any one of several well-known methods, including vacuum deposition or electrodeposition.
  • a suitable aqueous electro-plating bath for the codepositions of the present invention comprises an acid bath containing the sulfate salts of rhodium and platinum as described below.
  • the medals Before the silver base medals are plated with the rhodium-platinum alloy, the medals may be cleaned in a conventional manner, such as by electrocleaning, dipping in various cyanide dips, and/or treating with surface activators. After cleaning, a yellow-gold strike is applied according to well-known procedures such as for one minute at 6 amperes per square foot of afea. The gold strike provides a good seal on the silver base medal for subsequent plating with the rhodiumplatinum bath.
  • a particularly suitable apparatus for achieving both the gold strike and the rhodiumplatinum codeposition is as follows: a conventional electroplating tank is provided with platinized titanium anodes, and the medals are used as cathodes. The medals are suitably held in three fingered stainless steel racks, the fingers of the racks being spaced around the circumference of the medals approximately apart.
  • the racks are located about 4 to 5 inches from the anodes.
  • the medals should be rinsed according to the usual practice between each of the cleaning and plating steps.
  • a suitable electrolytic bath for the rhodium-platinum codeposition comprises an aqueous acidified bath of rhodium sulfate and platinum sulfate.
  • the two sulfate compounds should be present in approximately the same relative proportions as the desired relative proportions in the final alloy plating.
  • the relative concentrations of each of the sulfate compounds in the bath may be adjusted to the desired operating temperature and concentration, as will be obvious to one of ordinary skill in the art.
  • the electrolytic bath may suitably be operated at a total concentration of about 0.5 to grams per liter of the sulfate compounds and an operating temperature of about 150 to 200 F, and preferably l65 to 185 F.
  • the bath should also be maintained at an acid pH, and preferably a pH of about 1 to 3.5.
  • the bath may suitably be acidified with sulfuric acid or sulfamic acid.
  • the electrolytic bath may be operated at a current of between about 5 and 40 amperes per square foot of area for a time of about one-half to 5 minutes or more, depending upon the desired plating thickness. Currents above 40 amperes per square foot of area may produce burning of the plating and currents below about 5 amperes per square foot will be extremely inefficient and uneconomical from a time standpoint. A preferred operating current is about 20 amperes per square foot for about 1 to 2 minutes. The time will of course also be somewhat dependent upon the concentration of the metals in the electrolytic bath.
  • the electrolytic bath may also contain other wellknown components, such as buffers and cadmium or cobalt brighteners.
  • the silver medals are rinsed and dried according to conventional procedures as desired. For example, to obtain a particularly bright, clean silver appearance, the medals may be rinsed in hot deionized water and then dried.
  • the rhodium and platinum sulfates are present in relative concentrations such that the relative proportions of the two metals are approximately 3 to 5 weight percent platinum and 95 to 97 weight percent rhodium.
  • the codeposition is operated at a current of 20 amperes per square foot for approximately 1 minute.
  • Silver medals plated as in the above procedures have been subjected to accelerated tarnish tests using high concentrations of hydrogen sulfide and other common atmospheric pollutants. In addition, tests have been conducted by exposure of the thus plated silver medals to atmospheric conditions.
  • the tarnish resistance exhibited by the medals plated with the rhodiumplatinum alloy as above compares favorably with the tarnish resistance of silver medals plated with pure rhodium or coated with various lacquers or other resinous substances. More important, however, is the fact that the rhodium-platinum alloy platings of the present invention with the gold strike under-plating exhibit a visual appearance which is substantially identical to an untarnished, unplated sterling silver medal. To the best of my knowledge, such a duplication of the silver color and appearance has heretofore not been possible.
  • a tarnish resistant silver article comprising a silver base containing from about to 100 weight percent of silver, a flash layer of yellow gold overlying said silver base, and a tarnish resistant plating overlying said flash layer and having a thickness of from about 1 to 50 microinches, said plating comprising a metal alloy layer of about 91 to 99 weight percent rhodium and about 1 to 9 weight percent platinum, the outward visual appearance of said plating being substantially identical to the visual appearance of the unplated silver base.

Abstract

Articles made of silver or silver alloys containing a high percentage of silver, and particularly silver medals and medallions may be rendered tarnish resistant while still possessing a color closely matched to the original article by plating with a rhodium-platinum alloy. The alloy plating has a thickness of 1 to 50 microinches, and preferably 1 to 10 microinches, and comprises about 1 to 9 weight percent platinum, and preferably 3 to 5 weight percent platinum, with the remainder being rhodium. It is also necessary to provide the silver article with a flash plating of yellow gold prior to plating with the rhodium-platinum alloy in order to obtain the optimum color match.

Description

United States Patent [1 1 Karawin TARNISH RESISTANT PLATING FOR SILVER ARTICLES [75] Inventor: Kenneth J. Karawin, Chester Twsp.,
[73] Assignee: Franklin Mint Corporation, Franklin Center, Pa.
[22] Filed: Mar. 30, 1971 21 Appl. No.: 129,595
[52] US. Cl. 29/119, 75/172 E, 204/40, 204/43 [51] Int. Cl B32b 15/00 [58] Field of Search 29/199, 194; 204/40, 204/43, 47; 75/172 E 5 6] References Cited UNlTED STATES PATENTS 1,991,995 2/1935 Wise 204/47 2,027,358 1/1936 Powell et a1. 204/47 3,515,651 6/1970 Ohkubo et al. 204/43 R 1,947,180 2/1934 Bart 29/199 X 2,364,674 12/1944 Swift 29/199 X FOREIGN PATENTS OR APPLICATIONS 485,905 5/1938 Great Britain 204/43 R [451 July 31, 1973 1,003,848 9/1965 Great Britain 204/43 R OTHER PuaucArrous E. M. Wise, The Platinum Metals, Platinum Metals and Applied Physics Section, The international Nickel Company, Inc., 1953, p. 321-323.
Primary Examiner L. Dewayne Rutledge AttorneySeidel, Gonda & Goldhamme r [57] ABSTRACT Articles made of silver or silver alloys containing a high percentage of silver, and particularly silver medals and medallions may be rendered tarnish resistant while still possessing a color closely matched to the original article by plating with a rhodium-platinum alloy. The alloy plating has a thickness of l to 50 microinches, and preferably 1 to 10 microinches, and comprises about 1 to 9 weight percent platinum, and preferably 3 to 5 weight percent platinum, with the remainder being rhodium. It is also necessary to provide the silver article with a flash plating of yellow gold prior to plating with the rhodium-platinum alloy in order to obtain the optimum color match.
7 Claims, No Drawings TARNISH RESISTANT PLATING FOR SILVER ARTICLES The present invention relates to tarnish resistant silver articles and, more particularly, to tarnish resistant silver base medals and medallions containing about 80 to 100 weight percent of silver.
Silver and silver alloys, particularly fine silver and sterling silver, have long been highly preferred for medals, medallions, jewelry, tableware and various objects of art. This preference is due to the high reflectivity and elegant appearancev which make silver particularly attractive. Unfortunately, a major disadvantage of sterling silver and other silver alloys has been the relative ease with which the silver articles tarnish.
The problem of tarnishing of silver objects has become increasingly severe in recent years. The high concentration of air pollutants has resulted in more rapid and more extreme tarnishing. Particularly harmful tarnishing agents include cigarette smoke and hydrogen sulfide (H 8) which is increasingly present in the atmosphere as a product of fuel oil combustion and various industrial processes.
Much work has been done to develop a nontarnishing silver alloy but to the best of my knowledge no such alloy appears to exist at the present time. Also, various protective coatings and platings have been used to inhibit tarnish, but these attempts have been largely unsuccessful due to lack of commercial acceptance.
The major reason for the lack of widespread use of the various protective coatings appears to be due to the lack of durability. In respect to platings, the lack of commercial acceptance appears to be due to distortion of the characteristic color and high reflectivity which have made silver particularly desirable. For example, protective coatings of pure rhodium have been known for some time to provide excellent tarnish resistance. However, pure rhodium coatings have a cold bluish cast which does not satisfactorily match the silver color of the base material. Such matching of color is extremely important to collectors of silver medals and to owners of other articles made of silver alloys.
Accordingly, it is an object of the present invention to provide a satisfactory tarnish resistant plating for silver articles.
It is a further object of the present invention to provide tarnish resistant silver articles having a protective plating which substantially matches the color and appearance of the uncoated silver base.
It is another object of the present invention to provide tarnish resistant silver medals which are particularly resistant to hydrogen sulfide and cigarette smoke v and still possess the characteristic silver color and appearance. 1
Other objects will appear hereinafter.
The above and other objects of the present invention are achieved by providing silver base medals and other silver articles with a tarnish resistant plating having a thickness of about 1 to 50 microinches and consisting of a metal alloy of about 91 to 99 weight percent rhodium and about I to 9 weight percent platinum. The silver base medal is also provided with a thin layer of yellow gold underlying the rhodium-platinum alloy. It is to be understood that whereever the terms silver base medal or silver article are used throughout this specification, medals or articles containing from about 80 to 100 weight percent of silver are intended.
Although the present invention is in'te'ndedto cover any silver article containing about to 100 weight percent silver, the invention will be described with particular reference to silver medals. The silver base medals to be plated contain about 80 to 100 weight percent silver, and preferably to weight percent silver, the remainder being any of a number of alloying metals. The range of 90 to 100 weight percent silver encompasses both sterling silver (92.5 percent silver) and fine silver as well as other silver alloys. The remaining percentage is usually copper, which is alloyed with the silver. However, other alloying metals may be used.
The tarnish resistant plating which is applied to the silver base medals comprises a metal alloy of about 91 to 99 weight percent rhodium and about 1 to 9 weight percent platinum. A preferred alloy plating contains about 95 to 97 weight percent rhodium and about 3 to 5 weight percent platinum. It should be understood that the term alloy is intended to describe a codeposition of the rhodium and platinum, as opposed to separate depositions or platings of the two metals. Thus, a solidsolid solution of platinum in rhodium is obtained rather than two separate layers.
The codeposition or alloy plating may have a thickness of between about 1 and 50 microinches, and preferably l and 10 microinches. A parituclarly preferred codeposition has a thickness of about 2 to 3 microinches.
While the above described rhodium-platinum alloy platings alone provide excellent tarnish resistance, it is necessary in order to achieve completely satisfactory color matching that the silver base medals first be provided with a yellow gold (pure gold) strike or flash plating. The yellow gold flash plating should have a thickness of about I to 30 microinches, and preferably about 1 to 7 microinches. A yellow gold strike or flash plating followed by a rhodium-platinum codeposition of about 2 to 3 microinches provides a tarnish resistant plating resulting in a particularly good color match for sterling silver medals.
The rhodium-platinum codeposition or alloy platingmay be produced by any one of several well-known methods, including vacuum deposition or electrodeposition. A suitable aqueous electro-plating bath for the codepositions of the present invention comprises an acid bath containing the sulfate salts of rhodium and platinum as described below.
Before the silver base medals are plated with the rhodium-platinum alloy, the medals may be cleaned in a conventional manner, such as by electrocleaning, dipping in various cyanide dips, and/or treating with surface activators. After cleaning, a yellow-gold strike is applied according to well-known procedures such as for one minute at 6 amperes per square foot of afea. The gold strike provides a good seal on the silver base medal for subsequent plating with the rhodiumplatinum bath.
While almost any conventional electroplating apparatus may be adapted to produce the plating of the present invention, a particularly suitable apparatus for achieving both the gold strike and the rhodiumplatinum codeposition is as follows: a conventional electroplating tank is provided with platinized titanium anodes, and the medals are used as cathodes. The medals are suitably held in three fingered stainless steel racks, the fingers of the racks being spaced around the circumference of the medals approximately apart.
The racks are located about 4 to 5 inches from the anodes. The medals should be rinsed according to the usual practice between each of the cleaning and plating steps.
A suitable electrolytic bath for the rhodium-platinum codeposition comprises an aqueous acidified bath of rhodium sulfate and platinum sulfate. The two sulfate compounds should be present in approximately the same relative proportions as the desired relative proportions in the final alloy plating. However, since the relative proportions of each metal codeposited on the silver medal will depend somewhat on the operating temperature and total concentration of the bath, the relative concentrations of each of the sulfate compounds in the bath may be adjusted to the desired operating temperature and concentration, as will be obvious to one of ordinary skill in the art.
The electrolytic bath may suitably be operated at a total concentration of about 0.5 to grams per liter of the sulfate compounds and an operating temperature of about 150 to 200 F, and preferably l65 to 185 F. The bath should also be maintained at an acid pH, and preferably a pH of about 1 to 3.5. The bath may suitably be acidified with sulfuric acid or sulfamic acid.
The electrolytic bath may be operated at a current of between about 5 and 40 amperes per square foot of area for a time of about one-half to 5 minutes or more, depending upon the desired plating thickness. Currents above 40 amperes per square foot of area may produce burning of the plating and currents below about 5 amperes per square foot will be extremely inefficient and uneconomical from a time standpoint. A preferred operating current is about 20 amperes per square foot for about 1 to 2 minutes. The time will of course also be somewhat dependent upon the concentration of the metals in the electrolytic bath.
The electrolytic bath may also contain other wellknown components, such as buffers and cadmium or cobalt brighteners.
After the codeposition has been completed, the silver medals are rinsed and dried according to conventional procedures as desired. For example, to obtain a particularly bright, clean silver appearance, the medals may be rinsed in hot deionized water and then dried.
The plating of the present invention will now be illus trated with reference to the following specific, nonlimiting example:
Sterling silver medals having a diameter of approximately 1 inches and a thickness of approximately one-eighth inch and comprising 92.5 percent silver and approximately 7.5 percent copper are electro-cleaned and then provided with a yellow gold strike according to the above procedure at a current of 6 amperes per square foot for one minute. After rinsing the gold plated sterling silver medals are subjected to a rhodium-platinum electrolytic bath in an apparatus similar to that described above. The bath is operated at a total concentration of approximately 5 grams per liter of the rhodium and platinum sulfates at a temperature of approximately l80 F. The rhodium and platinum sulfates are present in relative concentrations such that the relative proportions of the two metals are approximately 3 to 5 weight percent platinum and 95 to 97 weight percent rhodium. The codeposition is operated at a current of 20 amperes per square foot for approximately 1 minute.
Silver medals plated as in the above procedures have been subjected to accelerated tarnish tests using high concentrations of hydrogen sulfide and other common atmospheric pollutants. In addition, tests have been conducted by exposure of the thus plated silver medals to atmospheric conditions. The tarnish resistance exhibited by the medals plated with the rhodiumplatinum alloy as above compares favorably with the tarnish resistance of silver medals plated with pure rhodium or coated with various lacquers or other resinous substances. More important, however, is the fact that the rhodium-platinum alloy platings of the present invention with the gold strike under-plating exhibit a visual appearance which is substantially identical to an untarnished, unplated sterling silver medal. To the best of my knowledge, such a duplication of the silver color and appearance has heretofore not been possible.
The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof and, accordingly, reference should be made to the appended claims, rather than to the foregoing specification as indicating the scope of the invention.
1 claim:
I. A tarnish resistant silver article comprising a silver base containing from about to 100 weight percent of silver, a flash layer of yellow gold overlying said silver base, and a tarnish resistant plating overlying said flash layer and having a thickness of from about 1 to 50 microinches, said plating comprising a metal alloy layer of about 91 to 99 weight percent rhodium and about 1 to 9 weight percent platinum, the outward visual appearance of said plating being substantially identical to the visual appearance of the unplated silver base.
2. A tarnish resistant silver article in accordance with claim 1 wherein said base is a silver medal.
3. A tarnish resistant silver article in accordance with claim 2, wherein said flash layer has a thickness of from about 1 to 30 microinches.
4. A tarnish resistant silver article in accordance with claim 3 wherein said alloy layer has a thickness of about i to 10 microinches and said flash layer has a thickness of about 1 to 7 microinches.
5. A tarnish resistant silver article in accordance with claim 4 wherein said alloy layer comprises about 95 to 97 weight percent rhodium and about 3 to 5 weight percent platinum.
6. A tarnish resistant article in accordance with claim 5 wherein said silver base is sterling silver and said plating has an outward visual appearance substantially identical to sterling silver.
7. A tarnish resistant silver article in accordance with claim 6 wherein said alloy layer and said flash layer each have a thickness of about 2 to 3 microinches.
i i i i i

Claims (6)

  1. 2. A tarnish resistant silver article in accordance with claim 1 wherein said base is a silver medal.
  2. 3. A tarnish resistant silver article in accordance with claim 2, wherein said flash layer has a thickness of from about 1 to 30 microinches.
  3. 4. A tarnish resistant silver article in accordance with claim 3 wherein said alloy layer has a thickness of about 1 to 10 microinches and said flash layer has a thickness of about 1 to 7 microinches.
  4. 5. A tarnish resistant silver article in accordance with claim 4 wherein said alloy layer comprises about 95 to 97 weight percent rhodium and about 3 to 5 weight percent platinum.
  5. 6. A tarnish resistant article in accordance with claim 5 wherein said silver base is sterling silver and said plating has an outward visual appearance substantially identical to sterling silver.
  6. 7. A tarnish resistant silver article in accordance with claim 6 wherein said alloy layer and said flash layer each have a thickness of about 2 to 3 microinches.
US00129595A 1971-03-30 1971-03-30 Tarnish resistant plating for silver articles Expired - Lifetime US3748712A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US12959571A 1971-03-30 1971-03-30

Publications (1)

Publication Number Publication Date
US3748712A true US3748712A (en) 1973-07-31

Family

ID=22440724

Family Applications (1)

Application Number Title Priority Date Filing Date
US00129595A Expired - Lifetime US3748712A (en) 1971-03-30 1971-03-30 Tarnish resistant plating for silver articles

Country Status (6)

Country Link
US (1) US3748712A (en)
CA (1) CA938177A (en)
DE (1) DE2205367B2 (en)
FR (1) FR2131314A5 (en)
GB (1) GB1363774A (en)
IT (1) IT948972B (en)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4590672A (en) * 1981-07-24 1986-05-27 Fujitsu Limited Package for electronic device and method for producing same
US6447664B1 (en) * 1999-01-08 2002-09-10 Scimed Life Systems, Inc. Methods for coating metallic articles
WO2003003883A1 (en) * 2001-07-05 2003-01-16 Alberto Schiavon Process for making cutlery set with precious stones and such cutlery
US20040237586A1 (en) * 2001-08-21 2004-12-02 Harald Plebuch Use of a mixture of crystals for stimulation of the thymus gland
US7118707B2 (en) 2004-03-31 2006-10-10 American Bullion Investment Company, Inc. Silver-platinum alloy and methods of manufacturing same
US20090218647A1 (en) * 2008-01-23 2009-09-03 Ev Products, Inc. Semiconductor Radiation Detector With Thin Film Platinum Alloyed Electrode
US20100078379A1 (en) * 2008-07-25 2010-04-01 Donaldson Company, Inc. Pleated filtration media, media packs, filter elements, and methods for filtering fluids
DE102008050135A1 (en) 2008-10-04 2010-04-08 Umicore Galvanotechnik Gmbh Process for depositing platinum rhodium layers with improved brightness

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
IT1396670B1 (en) * 2009-03-02 2012-12-14 Aura S R L L DEVICE FOR IMPROVING THE PHYSICAL PERFORMANCE AND THE ABILITY TO MAINTAIN THE BALANCE OF AN INDIVIDUAL, AND A RELATIVE MANUFACTURING METHOD

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1947180A (en) * 1930-05-31 1934-02-13 Precious Metals Developing Com Tarnish resisting silver
US1991995A (en) * 1932-10-03 1935-02-19 Int Nickel Co Platinum metal ammino cyanide plating bath and process for electrodeposition of platinum metal therefrom
US2027358A (en) * 1931-03-12 1936-01-07 Johnson Matthey Co Ltd Electrodeposition of metals of the platinum group
GB485905A (en) * 1936-03-11 1938-05-26 Marret Bonnin Lebel & Guieu Ets Process for protecting an article made of a tarnishable metal such as silver
US2364674A (en) * 1939-11-27 1944-12-12 Swift & Sons Inc M Metallic leaf
GB1003848A (en) * 1963-07-29 1965-09-08 Johnson Matthey Co Ltd Improvements in and relating to the protection of metallic surfaces
US3515651A (en) * 1966-02-07 1970-06-02 Katsuhiro Ohkubo Plating solutions for rhodium and rhodium alloy platings having low internal stress

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1947180A (en) * 1930-05-31 1934-02-13 Precious Metals Developing Com Tarnish resisting silver
US2027358A (en) * 1931-03-12 1936-01-07 Johnson Matthey Co Ltd Electrodeposition of metals of the platinum group
US1991995A (en) * 1932-10-03 1935-02-19 Int Nickel Co Platinum metal ammino cyanide plating bath and process for electrodeposition of platinum metal therefrom
GB485905A (en) * 1936-03-11 1938-05-26 Marret Bonnin Lebel & Guieu Ets Process for protecting an article made of a tarnishable metal such as silver
US2364674A (en) * 1939-11-27 1944-12-12 Swift & Sons Inc M Metallic leaf
GB1003848A (en) * 1963-07-29 1965-09-08 Johnson Matthey Co Ltd Improvements in and relating to the protection of metallic surfaces
US3515651A (en) * 1966-02-07 1970-06-02 Katsuhiro Ohkubo Plating solutions for rhodium and rhodium alloy platings having low internal stress

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
E. M. Wise, The Platinum Metals, Platinum Metals and Applied Physics Section, The International Nickel Company, Inc., 1953, p. 321 323. *

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4590672A (en) * 1981-07-24 1986-05-27 Fujitsu Limited Package for electronic device and method for producing same
US6447664B1 (en) * 1999-01-08 2002-09-10 Scimed Life Systems, Inc. Methods for coating metallic articles
WO2003003883A1 (en) * 2001-07-05 2003-01-16 Alberto Schiavon Process for making cutlery set with precious stones and such cutlery
US20040237586A1 (en) * 2001-08-21 2004-12-02 Harald Plebuch Use of a mixture of crystals for stimulation of the thymus gland
US8313753B2 (en) * 2001-08-21 2012-11-20 Harald Plebuch Use of a mixture of crystals for stimulation of the thymus gland
US7118707B2 (en) 2004-03-31 2006-10-10 American Bullion Investment Company, Inc. Silver-platinum alloy and methods of manufacturing same
US20090218647A1 (en) * 2008-01-23 2009-09-03 Ev Products, Inc. Semiconductor Radiation Detector With Thin Film Platinum Alloyed Electrode
US8896075B2 (en) 2008-01-23 2014-11-25 Ev Products, Inc. Semiconductor radiation detector with thin film platinum alloyed electrode
US20100078379A1 (en) * 2008-07-25 2010-04-01 Donaldson Company, Inc. Pleated filtration media, media packs, filter elements, and methods for filtering fluids
DE102008050135A1 (en) 2008-10-04 2010-04-08 Umicore Galvanotechnik Gmbh Process for depositing platinum rhodium layers with improved brightness
WO2010037495A1 (en) * 2008-10-04 2010-04-08 Umicore Galvanotechnik Gmbh Process for the deposition of platinum-rhodium layers having improved whiteness
US20110308959A1 (en) * 2008-10-04 2011-12-22 Umicore Galvanotechnik Gmbh Process for the deposition of platinum-rhodium layers having improved whiteness

Also Published As

Publication number Publication date
DE2205367A1 (en) 1972-10-12
IT948972B (en) 1973-06-11
DE2205367B2 (en) 1973-09-13
GB1363774A (en) 1974-08-14
FR2131314A5 (en) 1972-11-10
CA938177A (en) 1973-12-11
DE2205367C3 (en) 1974-04-11

Similar Documents

Publication Publication Date Title
KR940001680B1 (en) Platinum electroforming and platinum electroplating
US3420754A (en) Electroplating a ductile zinc-nickel alloy onto strip steel
US3994694A (en) Composite nickel-iron electroplated article
JPS5838517B2 (en) Method of plating corrosion-resistant protective coatings on iron or steel substrates
US1615585A (en) Process of producing corrosion-resisting coatings on iron and steel and product
WO2002000958A1 (en) Decorative article having white film and production method therefor
US3748712A (en) Tarnish resistant plating for silver articles
GB2155493A (en) Electroplating zinc-iron alloy from alkaline bath
US1931704A (en) Process of protecting ferrous metals
US6413653B1 (en) Personal ornament covered with colored coating and process for producing the same
US3294498A (en) Cr-fe diffusion coating ferrous metal substrate
EP1778888A1 (en) Chromium plating
US2162789A (en) Method of preparing metal surface for plating
US6258415B1 (en) Iron-plated aluminum alloy parts and method for planting same
US3298802A (en) Method for covering objects with a decorative bright-nickel/chromium coating, as well as objects covered by applying this method
US5085744A (en) Electroplated gold-copper-zinc alloys
US6372118B1 (en) Ni-Fe-Co electroplating bath
US2468825A (en) Plating
US5792565A (en) Multiple layered article having a bright copper layer
JP2577832B2 (en) Platinum electroforming bath
US3778259A (en) Alloy of tin, silver and nickel
JP2003013282A (en) Ornament and manufacturing method therefor
JP2537001B2 (en) Spring wire having solderability and corrosion resistance, and method of manufacturing the same
US4143210A (en) Multi-layer plating for improved corrosion resistance
Faust Electrodeposition of Alloys, 1930 to 1940

Legal Events

Date Code Title Description
AS Assignment

Owner name: FIRST NATIONAL BANK OF BOSTON, THE, 100 FEDERAL ST

Free format text: SECURITY INTEREST;ASSIGNOR:FRANKLIN MINT COMPANY;REEL/FRAME:004390/0804

Effective date: 19850326

AS Assignment

Owner name: WCI-MINT CORP., 75 ROCKEFELLER PLAZA, NEW YORK, NE

Free format text: ASSIGNS NUNC PR TUNC AS OF MARCH 2, 1981 THE ENTIRE INTEREST IN SAID PATENTS;ASSIGNOR:WARNER COMMUNICATIONS, INC.;REEL/FRAME:004383/0996

Effective date: 19850326

Owner name: NEW FRANKLIN MINT, FRANKLIN CENTER, PA. 19091, A

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:FRANKLIN MINT CORPORATION;REEL/FRAME:004383/0991

Effective date: 19850326

Owner name: FRANKLIN MINT CORPORATION

Free format text: CHANGE OF NAME;ASSIGNOR:WCI-MINT CORP.;REEL/FRAME:004386/0344

Effective date: 19810302

Owner name: WARNER COMMUNICATIONS INC. A CORP. OF DE

Free format text: MERGER;ASSIGNOR:FRANKLIN MINT CORPORATION A CORP OF DE;REEL/FRAME:004386/0336

Effective date: 19810302

AS Assignment

Owner name: FIRST NATIONAL BANK OF BOSTON, THE, AS AGENT

Free format text: LICENSE;ASSIGNOR:FIRST NATIONAL BANK OF BOSTON, THE, AS COLLATERAL AGENT;REEL/FRAME:004818/0798

Effective date: 19871021

Owner name: FIRST NATIONAL BANK OF BOSTON, THE AS COLLATERAL A

Free format text: AMENDED SECURITY AGREEMENT;ASSIGNORS:FRANKLIN MINT COMPANY;FIRST NATIONAL BANK OF BOSTON, THE, AS AGENT;REEL/FRAME:004818/0793

Effective date: 19871021

Owner name: FRANKLIN MINT COMPANY

Free format text: LICENSE;ASSIGNOR:FIRST NATIONAL BANK OF BOSTON, THE, AS COLLATERAL AGENT;REEL/FRAME:004818/0798

Effective date: 19871021

AS Assignment

Owner name: FRANKLIN MINT COMPANY, A DE GENERAL PARTNERSHIP CO

Free format text: LICENSE;ASSIGNOR:FIRST NATIONAL BANK OF BOSTON, THE, COLLATERAL AGENT;REEL/FRAME:005025/0091

Effective date: 19880803

Owner name: FRANKLIN MINT COMPANY, DE GENERAL PARTNERSHIP COMP

Free format text: RELEASED BY SECURED PARTY;ASSIGNOR:FIRST NATIONAL BANK OF BOSTON, THE, AS COLLATERAL AGENT;REEL/FRAME:005025/0085

Effective date: 19880803