US1967716A - Method of chromium plating - Google Patents

Method of chromium plating Download PDF

Info

Publication number
US1967716A
US1967716A US585808A US58580832A US1967716A US 1967716 A US1967716 A US 1967716A US 585808 A US585808 A US 585808A US 58580832 A US58580832 A US 58580832A US 1967716 A US1967716 A US 1967716A
Authority
US
United States
Prior art keywords
chromium
current
density
plated
bath
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
US585808A
Inventor
Mahlstedt Henry
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.)
United Chromium Inc
Original Assignee
United Chromium Inc
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 United Chromium Inc filed Critical United Chromium Inc
Priority to US585808A priority Critical patent/US1967716A/en
Application granted granted Critical
Publication of US1967716A publication Critical patent/US1967716A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Classifications

    • CCHEMISTRY; METALLURGY
    • C25ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25DPROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D5/00Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
    • CCHEMISTRY; METALLURGY
    • C25ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25DPROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D21/00Processes for servicing or operating cells for electrolytic coating
    • C25D21/02Heating or cooling
    • CCHEMISTRY; METALLURGY
    • C25ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25DPROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D3/00Electroplating: Baths therefor
    • C25D3/02Electroplating: Baths therefor from solutions
    • C25D3/04Electroplating: Baths therefor from solutions of chromium

Definitions

  • This invention relates to methods of chromium plating, and particularly to a method of plating whereby chromium may be deposited without exposure of the metal underlying the chro-' 5 mium plate by reason of cracks or pores, or with a minimum of such exposure, and provides improvements therein.
  • pedients should be used to obtain uniformity of the current density over the entire surface to be plated, particularly on such projections or high spots and around such edges, expedients for this purpose being shields, robbers or special anodes.
  • the article to be chromiumplated is placed as cathode in a chromium-plating bath ofdefinite composition (such for example as described in Fink Patents Nos. 1,581,188
  • the range of current density for the chosen temperature and bath composition may be found bypassing current through" the solution to a series of similar test articles to be plated, starting from a point of low current density at which no deposit is obtained and increasing by steps, to a point where the article being plated is first completelycovered with chromium.
  • This current density should be noted and may be designated as (a).
  • the chromium plate obtained at this current density (a) will generally be milky.
  • the currentdensity should then be increased to a point where a bright mirror-surface deposit which completely covers the article is first obtained.
  • This current-density should be noted and may be designated as (b).
  • the current-density can then be further increased to a point where nodular or, burnt deposits are first observed.
  • This current-density should be noted and may be designated as (c).
  • the current densities which give the advantages herein described, and which are herein spoken of as current densities in the lower part of the current density range are those from (a) as described above to about half-way between (D) and (c).
  • the surface of the article to be plated is made passive by the chromic acid bath or enters the chromic acid bath in a so-called passive condition (nickel-plated articles for example) the surface should be struck or flashed, as by raising the plating voltage momentarily.
  • Milky deposits, where desired, may be bufied to produce a mirror surface.
  • the chromium plate should not be less than .00002 inch thick.
  • a mode of procedure for producing omamental mirror-surface chromium-plate on commercial articles (such as a waffle iron cover) having a color-buffed mirror nickel surface prior to plating, and on which there is substantially no exposure of the nickel surface underlying the chromium deposit (little or no cracks or pores) as revealed by the aforesaid Dubpernell test, is substantially as follows:
  • the current-density range for obtaining good ornamental mirroresurface plate on such walate iron covers is approximately'z to 4 amperes per square inch.
  • Chromium deposits obtained in accordance with this process give superior results in resisting atmospheric corrosion to deposits heretofore obtainable.
  • the invention may be carried out by other modes of procedure than those herein specifically described.
  • a method of chromium-plating from aqueous baths of the chromic acid type to produce chromium plated articles on which there is no exposure or minimum exposure of the metal underlying the chromium plate comprising passing current to the article to .be plated as a cathode, in a bath of definite composition at a substantially constant temperature above 45 0., and at a current-density substantially uniform over the surface to be plated, in the lower part of the current-density range for the solution composition and temperature chosen.
  • a method of chromium-plating from aqueous baths of the chromic acid type to produce chromium plated articles on which there is no ex e or minimum exposure of the metal und I ying the chromium plate comprising passing current to the article to be plated as a cathode, in a bath of definite composition at a substantially constant temperature above 45 C.-, and at a current-density substantially uniform over the surface to be plated, in the lower part of the current-density range for the solution composition and temperature chosen,

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Electroplating And Plating Baths Therefor (AREA)
  • Electroplating Methods And Accessories (AREA)

Description

Patented. July 24, 1934 UNITED STATES PATENT OFFICE United Ghromium,
Incorporated, New York,
N. Y., a corporation of Delaware N Drawing. Application January 9, 1932, Serial No. 585,808
6 Claims. (01. 204-1) This invention relates to methods of chromium plating, and particularly to a method of plating whereby chromium may be deposited without exposure of the metal underlying the chro-' 5 mium plate by reason of cracks or pores, or with a minimum of such exposure, and provides improvements therein.
Baker and Rente, in Transactions of American Electrochemical Society, Vol. 54, page 337 (1928) have discussed the question of high temperatures of the chromium plating bath as related to the porosity of chromium plate.
I have discovered, in order to obtain chromium plated articles on which the underlying metal is not exposed, the chromium plated article not showing copper deposits when placed as cathode in an acid copper plating cell for a'limited time (Dubpernells method), or on which there is only slight exposure as revealed by fine copper lines when tested by said Dubpernell method, that not only is it desirable to use a relatively high temperature of the bath but a currentdensity should be used which at the temperature (and bath composition) employed is the 5 minimum which will produce a coating of chromium over the surface to be plated, or in the lower part of the current density range for that temperature. Also, to secure the minimum of exposure of the underlying metal, on articles having pronounced edges or projections, ex-
pedients should be used to obtain uniformity of the current density over the entire surface to be plated, particularly on such projections or high spots and around such edges, expedients for this purpose being shields, robbers or special anodes.
According to the present invention, in order to obtain chromium plated articles on which the metal underlying the chromium plate is not ex- 0 posed by pores and cracks, or with the minimum of such exposure, the article to be chromiumplated is placed as cathode in a chromium-plating bath ofdefinite composition (such for example as described in Fink Patents Nos. 1,581,188
and 1,802,463) having a relatively constant temperature above 45 C., and plated with chromium at a current density in the lower part of the range of current density for producing a bright or mirror surface plate for the temperature and bath composition chosen, or at current densities below the range for mirrorsurface deposits, the current densities being those which produce deposits which completely cover the surface to be plated.
The range of current density for the chosen temperature and bath composition may be found bypassing current through" the solution to a series of similar test articles to be plated, starting from a point of low current density at which no deposit is obtained and increasing by steps, to a point where the article being plated is first completelycovered with chromium. This current density should be noted and may be designated as (a). The chromium plate obtained at this current density (a) will generally be milky. The currentdensity should then be increased to a point where a bright mirror-surface deposit which completely covers the article is first obtained. This current-density should be noted and may be designated as (b). The current-density can then be further increased to a point where nodular or, burnt deposits are first observed. This current-density should be noted and may be designated as (c). The current densities which give the advantages herein described, and which are herein spoken of as current densities in the lower part of the current density range are those from (a) as described above to about half-way between (D) and (c).
To avoid error in obtaining the current density for initial deposits in some cases where the surface of the article to be plated is made passive by the chromic acid bath or enters the chromic acid bath in a so-called passive condition (nickel-plated articles for example) the surface should be struck or flashed, as by raising the plating voltage momentarily.
Milky deposits, where desired, may be bufied to produce a mirror surface.
To secure the advantages of the invention, the chromium plate should not be less than .00002 inch thick.
A mode of procedure for producing omamental mirror-surface chromium-plate on commercial articles (such as a waffle iron cover) having a color-buffed mirror nickel surface prior to plating, and on which there is substantially no exposure of the nickel surface underlying the chromium deposit (little or no cracks or pores) as revealed by the aforesaid Dubpernell test, is substantially as follows:
Bath, 400 grams per liter CrOa. 4 grams per liter S04.
Temperature, 55 C.
Current density (with high spots protected against concentration of current), 2.25 amperes per sq. inch.
Time, 3 minutes.
,With a bath having the composition and temperature stated, the current-density range for obtaining good ornamental mirroresurface plate on such waiile iron covers is approximately'z to 4 amperes per square inch.
For a longer time of plating at the above temperaturev and with the bath composition given, a current-density from 1.2 to 2 amperes per square inch is recommended, the surface of the chromium plate at the lower currentdensities b'eing milky.
For a temperature of 50- C. with a bath of the composition given above, a current-density of around 1.5 amperes per square inch is recamended for obtaining chromium deposits having a mirror surface.
For a temperature of 60 C. with a bath of the composition given above, a current density of 2.5 to 3 amperes per square inch is recommended for obtaining chromium deposits having a mirror surface, but at this temperature and above the deposits have a quite perceptible bluish tinge which at the present time is not ordinarily desired for ornamental chromium plate.
Chromium deposits obtained in accordance with this process give superior results in resisting atmospheric corrosion to deposits heretofore obtainable.
The invention may be carried out by other modes of procedure than those herein specifically described.
What is claimed is:-
1. A method of chromium-plating from aqueous baths of the chromic acid type to produce chromium plated articles on which there is no exposure or minimum exposure of the metal underlying the chromium plate, comprising passing current to the article to .be plated as a cathode, in a bath of definite composition at a substantially constant temperature above 45 0., and at a current-density substantially uniform over the surface to be plated, in the lower part of the current-density range for the solution composition and temperature chosen.
2. A method of chromium-plating from aqueous baths of the chromic acid type to produce chromium plated articles on which there is no ex e or minimum exposure of the metal und I ying the chromium plate, comprising passing current to the article to be plated as a cathode, in a bath of definite composition at a substantially constant temperature above 45 C.-, and at a current-density substantially uniform over the surface to be plated, in the lower part of the current-density range for the solution composition and temperature chosen,
.and in that part of said lower part of the current-density range at which mirror-surface chromium deposits are obtained.
3. A method according to claim 2 wherein the 1byath temperature does not exceed approximate- 4. A method according to claim 1 wherein the bath temperature is approximately 55 C. and the current-density from 1.2 to 3 amperes per square inch.
5. A method according to claim 2 wherein the bath temperature is approximately 55 C. and the current-density from 2 to 2% amperes per square inch.
6. A method according to claim 1 wherein the plating is continued to produce a plate exceeding 0.00002 inch.
HENRY MAI-ILS'IED'I.
US585808A 1932-01-09 1932-01-09 Method of chromium plating Expired - Lifetime US1967716A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US585808A US1967716A (en) 1932-01-09 1932-01-09 Method of chromium plating

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US585808A US1967716A (en) 1932-01-09 1932-01-09 Method of chromium plating

Publications (1)

Publication Number Publication Date
US1967716A true US1967716A (en) 1934-07-24

Family

ID=24343049

Family Applications (1)

Application Number Title Priority Date Filing Date
US585808A Expired - Lifetime US1967716A (en) 1932-01-09 1932-01-09 Method of chromium plating

Country Status (1)

Country Link
US (1) US1967716A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2547120A (en) * 1945-10-23 1951-04-03 Bendix Aviat Corp Process for plating a carbon or graphite part with chromium
US2739932A (en) * 1952-09-05 1956-03-27 Clarence W Forestek Electrodepositing chromium on aluminum

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2547120A (en) * 1945-10-23 1951-04-03 Bendix Aviat Corp Process for plating a carbon or graphite part with chromium
US2739932A (en) * 1952-09-05 1956-03-27 Clarence W Forestek Electrodepositing chromium on aluminum

Similar Documents

Publication Publication Date Title
US1792082A (en) Metallic coating and process of producing the same
US3247082A (en) Electrodeposition of a corrosion resistant coating
US2250556A (en) Electrodeposition of copper and bath therefor
US2623847A (en) Black chromium plating
US1971761A (en) Protection of metals
US3326782A (en) Bath and method for electroforming and electrodepositing nickel
US3388049A (en) Method of electrodepositing microcrack chromium coatings
US3500537A (en) Method of making palladium coated electrical contacts
US3558442A (en) Electroplating a ductile zinc-nickel alloy onto strip steel
US1928284A (en) Process of electrodepositing chromium
US1967716A (en) Method of chromium plating
US3511759A (en) Method and electrolytes for electro-depositing black chromium
US3009236A (en) Protective and decorative coatings containing nickel
US3207679A (en) Method for electroplating on titanium
US1651278A (en) Process of producing corrosion-resisting coating on iron and steel and products
US902755A (en) Electrolyte for electroplating.
US3445351A (en) Process for plating metals
EP0097643B1 (en) Zinc-nickel electroplated article and method for producing the same
US2437612A (en) Process for electrolytically zinc plating magnesium and magnesium base alloys
US2461933A (en) Rhodium alloy coatings and method of making same
US2336568A (en) Method of metal electroplating
US3720588A (en) Black chromium plating process
US2172344A (en) Method of chromium plating
US1717468A (en) Electroplating process
US2574305A (en) Activating process for plating