US2473923A - Electrolytic polishing process - Google Patents

Electrolytic polishing process Download PDF

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Publication number
US2473923A
US2473923A US572589A US57258945A US2473923A US 2473923 A US2473923 A US 2473923A US 572589 A US572589 A US 572589A US 57258945 A US57258945 A US 57258945A US 2473923 A US2473923 A US 2473923A
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US
United States
Prior art keywords
silver
current
electrolyte
polishing
cyanide
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
US572589A
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English (en)
Inventor
Dennis R Turner
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.)
Westinghouse Electric Corp
Original Assignee
Westinghouse Electric 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
Priority to BE469081D priority Critical patent/BE469081A/xx
Application filed by Westinghouse Electric Corp filed Critical Westinghouse Electric Corp
Priority to US572589A priority patent/US2473923A/en
Priority to GB29508/46A priority patent/GB617487A/en
Priority to FR938732D priority patent/FR938732A/fr
Application granted granted Critical
Publication of US2473923A publication Critical patent/US2473923A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25F—PROCESSES FOR THE ELECTROLYTIC REMOVAL OF MATERIALS FROM OBJECTS; APPARATUS THEREFOR
    • C25F3/00—Electrolytic etching or polishing
    • C25F3/16—Polishing
    • C25F3/22—Polishing of heavy metals

Definitions

  • Silver when cleaned and polished, presents a bright, attractive appearance, and such polished surfaces are necessary and desirable in apparatus, household ware and other devices embodying silver or silver alloys.
  • the object of this invention is to electropolish rapidly and conveniently silver and its alloys in an electrolyte by applying alternating current.
  • silver and its alloys are electropolished in a brief period of time by employing an alternating electrical current in combination with an alkaline cyanide electrolyte.
  • silver it is meant silver metal and alloys composed of silver as the main constituent. both plated and solid.
  • the electrolyte to be applied to the silver surfaces consists of at least 2 grams per liter of cyanide and suflicient of another more readily ionizable non-acidic compound to give good electrical conductivity to the solution.
  • a solution composed of 32 grams per liter of potassium cyanide and 8 grams per liter of potassium hydroxide gave excellent results in practice. From 2 to 50 grams per liter of cyanide is suitable to accomplish the purpose of the invention.
  • Various neutral salts and alkaline compounds may be added to the electrolyte in order to attain the desired electrical conductivity. As an example. with 32 grams per liter of potassium cyanide, 10 grams per liter of any of the following compounds gave excellent results:
  • the amount of the conducting compounds may be more or less than this amount. As much as grams per liter is not excessive while 5 grams perliter is operative. Obviously, compounds detrimental to silver should not be added to the electrolyte. Mixtures of the easily ionizable compounds may be employed for this purpose.
  • the electrolyte after the additions of the ionizable compound and the cyanide is preferably alkaline in reaction. 7
  • the electrolyte may be at any temperature up to the boiling point. Room temperatures are preferred although it will be found that the polishing proceeds somewhat faster at higher temperatures.
  • the members are connected to one terminal from a source of alternating current and immersed in a bath of the hot electrolyte prepared as described above.
  • the other terminal from the source of alternating current may be connected either to a similar silver member or to an inert anode, such, for example, as nickel or nickel-plated steel.
  • the nickel electrodes should be shaped or disposed to give a reasonable degree of uniformity of current over the surface of the silver member being electropolished since the throwing power of the bath is moderate.
  • a current of at least 100 amperes per square foot is required at a frequency of 0.1 cycle per second, the minimum current density for an alternating electrical current of a frequency of between 0.1 and 0.6 cycle per second increasing from at least 100 amperes per square foot at 0.1 cycle per second, and following curve In in the drawing, and the minimum current density rising to a value of 800 amperes per square foot with 60 cycles per second electrical current.
  • polishing will be effected mostly at the edges and corners of the silver member and will be unsatisfactory. Operating in area B, satisfactory polishing is not secured even when the time of treatment exceeds 30 seconds.
  • direct current or rectified alternating current may be reversed periodically by a suitable motor-operated reverse switching means.
  • the voltage need only be two to three volts. In some cases, the voltage may be higher.
  • the electrolyte appears to function to give a satisfactory polished silver surface on members in from 5 to 30 seconds, depending upon the temperature of the electrolyte, concentration of the cyanide, the current density, and the frequency of the electrical current. In some cases, a small amount of agitation of the electrolyte or electrodes has been found to be beneficial.
  • the silver member is briefly immersed in a acid bath using sulfuric acid and rinsed again with water.
  • the silver member may be dried and is immediately ready for use.
  • the process herein indicated may be applied 4 to household silverware, jawelry of all kinds, silver-plated apparatus, silver contacts, silver or silver-plated electrical resonators, and any similar type of silver or silver-plated device.
  • the method of polishing members whose surfaces are composed of silver comprising, immersing the members in an aqueous electrolyte composed of from 2 to 50 grams per liter of alkali cyanide and from about 5 to 100 grams per liter of another readily ionizable, non-acidic compound, passing an alternating electrical current through the members having a frequency of from about 0.1 cycle to 60 cycles per second and at a current density of from at least 100 amperes'per square foot at 0.1 cycle per second to at'least 800 amperes per square foot at sixty cycles per second, up to a maximum of 5000 amperes per square foot applied for a period of from 5 to 30 seconds to electropolish the silver surfaces, and removing the member from the electrolyte when the current renders it anodic for frequencies of between 0.1 and 0.2 cycle per second.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Electroplating Methods And Accessories (AREA)
  • Electroplating And Plating Baths Therefor (AREA)
US572589A 1945-01-13 1945-01-13 Electrolytic polishing process Expired - Lifetime US2473923A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
BE469081D BE469081A (en)van) 1945-01-13
US572589A US2473923A (en) 1945-01-13 1945-01-13 Electrolytic polishing process
GB29508/46A GB617487A (en) 1945-01-13 1946-10-03 Improvements in or relating to the electrolytic polishing of silver
FR938732D FR938732A (fr) 1945-01-13 1946-10-31 Procédé de polissage

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US572589A US2473923A (en) 1945-01-13 1945-01-13 Electrolytic polishing process

Publications (1)

Publication Number Publication Date
US2473923A true US2473923A (en) 1949-06-21

Family

ID=24288503

Family Applications (1)

Application Number Title Priority Date Filing Date
US572589A Expired - Lifetime US2473923A (en) 1945-01-13 1945-01-13 Electrolytic polishing process

Country Status (4)

Country Link
US (1) US2473923A (en)van)
BE (1) BE469081A (en)van)
FR (1) FR938732A (en)van)
GB (1) GB617487A (en)van)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2559263A (en) * 1947-05-15 1951-07-03 Wallace & Sons Mfg Company R Electropolishing of metals
US2610144A (en) * 1947-02-08 1952-09-09 Oneida Ltd Method of electropolishing
US2610143A (en) * 1947-02-08 1952-09-09 Oneida Ltd Method of electropolishing
US20040040863A1 (en) * 2002-08-29 2004-03-04 Micron Technology, Inc. Systems for electrolytic removal of metals from substrates
US20050016869A1 (en) * 2002-08-29 2005-01-27 Micron Technology, Inc. Systems and methods for the electrolytic removal of metals from substrates
US11873572B2 (en) 2019-04-09 2024-01-16 3DM Biomedical Pty Ltd Electropolishing method

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE225873C (en)van) *
US1527734A (en) * 1922-12-14 1925-02-24 Electrolytic Corp Apparatus and method for electrolytically depositing metals
FR707526A (fr) * 1930-03-14 1931-07-09 Materiel Telephonique Perfectionnements aux traitements électrolytiques des métaux

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE225873C (en)van) *
US1527734A (en) * 1922-12-14 1925-02-24 Electrolytic Corp Apparatus and method for electrolytically depositing metals
FR707526A (fr) * 1930-03-14 1931-07-09 Materiel Telephonique Perfectionnements aux traitements électrolytiques des métaux

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2610144A (en) * 1947-02-08 1952-09-09 Oneida Ltd Method of electropolishing
US2610143A (en) * 1947-02-08 1952-09-09 Oneida Ltd Method of electropolishing
US2559263A (en) * 1947-05-15 1951-07-03 Wallace & Sons Mfg Company R Electropolishing of metals
US20040040863A1 (en) * 2002-08-29 2004-03-04 Micron Technology, Inc. Systems for electrolytic removal of metals from substrates
US20050016869A1 (en) * 2002-08-29 2005-01-27 Micron Technology, Inc. Systems and methods for the electrolytic removal of metals from substrates
US11873572B2 (en) 2019-04-09 2024-01-16 3DM Biomedical Pty Ltd Electropolishing method

Also Published As

Publication number Publication date
GB617487A (en) 1949-02-07
FR938732A (fr) 1948-10-22
BE469081A (en)van)

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