US2952590A - Process for chromium plating - Google Patents

Process for chromium plating Download PDF

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Publication number
US2952590A
US2952590A US833765A US83376559A US2952590A US 2952590 A US2952590 A US 2952590A US 833765 A US833765 A US 833765A US 83376559 A US83376559 A US 83376559A US 2952590 A US2952590 A US 2952590A
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US
United States
Prior art keywords
chromium
ion
concentration
bright
crack
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
US833765A
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English (en)
Inventor
Jesse E Stareck
Jr Edgar J Seyb
Johnson Andy Albert
William H Rowan
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Primerica Inc
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Metal and Thermit 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.)
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Publication date
Application filed by Metal and Thermit Corp filed Critical Metal and Thermit Corp
Priority to US833765A priority Critical patent/US2952590A/en
Priority to DE19601446015 priority patent/DE1446015B2/de
Priority to GB27566/60A priority patent/GB954033A/en
Priority to FR835691A priority patent/FR1264979A/fr
Priority to SE7748/60A priority patent/SE309521B/xx
Application granted granted Critical
Publication of US2952590A publication Critical patent/US2952590A/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
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D3/00—Electroplating: Baths therefor
    • C25D3/02—Electroplating: Baths therefor from solutions
    • C25D3/04—Electroplating: Baths therefor from solutions of chromium
    • 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
    • Y10S428/9335—Product by special process
    • Y10S428/934—Electrical process
    • Y10S428/935—Electroplating
    • 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
    • Y10T428/12806—Refractory [Group IVB, VB, or VIB] metal-base component
    • Y10T428/12826—Group VIB metal-base component
    • Y10T428/12847—Cr-base component

Definitions

  • the present invention relates to a novel process for electrodepositin-g chromium, and more particularly, to a process for electrodepositing bright crack-free chromium plate.
  • This application is a continuation-in-part application of our patent application Serial No. 695,146, filed November 7, 1957, now Patent No. 2,916,424.
  • Chromium is widely used as a decorative and protective surface finish.
  • Decorative chromium plate. is usually of too small a thickness, in the order of 0.00001 inch, .to be of substantial value for protecting the basis metal... When deposited greater thicknesses, the plate contains a network of hair-like cracks extending through the chromium to the basis metal, destroying the plates protective value.
  • decorative electrodeposit, copper and/ or nickel are deposited on the basis metal to provide effective corrosion resistance, followed by deposition of the usual thin decorative chromium finish. Thick deposits of chromium are deposited directly on the basis metal or over a copper and/ or nickel undercoat to provide fairly effective protection against corrosion and wear.
  • Chromium deposits in the order of 0.00005 inch, 0.0001 inch and greater, which are bright and crack-free, as plated, are desirable for providing decorative chromium plates having good corrosion resistance. It has been found that for a given thickness of deposit, e.g., 0.00005 inch,
  • the corrosion resistance of crack-free deposits is far superior to the corrosion resistance of deposits having a crack pattern, even including those deposits ot'sutficient thickness that the cracks are healed.
  • the art has not known how to obtain thick,
  • the term bright in describing bright crack-free chromium electrodeposits, as used herein, is limited to surfaces which have suffioient reflectivity to render a well defined and recognizable image.
  • the bright range of deposits is divided into two subdivisions-deposits referred to as mirror-bright and deposits referred to as bright.
  • the mirror-bright deposits are those which have the reflectivity ordinarily associated with a good mirror.
  • the bright deposits have a lesser degree of reflectivity than a good mirror, but sufiicient reflectivity to render a well defined and recognizable image.
  • These bright deposits are suificient-ly bright as plated to be acceptable decorative finishes. Their degree of brightness may be improved by a buifing operation to achieve mirror brightness.
  • the term bright crack-free chromium encompasses those deposits which are mirror-bright and bright, as defined herein.
  • Ratio the ratio of the weight of CrO to the total weight or all the catalyst ions
  • baths having lower catalyst concentrations must be employed. Baths with very low catalyst concentrations, as noted by Ratios as high as 150:1, may be utilized at temperatures as low as 95 F. As the temperature is raised, the tendency to electrodeposit bright chromium decreases. Dull deposits are obtained at high temperatures. The upper temperature limit for obtaining bright chromium operative over most of the range of CrO concentrations is 140 F. The temperature and Ratios at which bright crack-free chromium may be obtained are also related to the CIO;, concentration of the bath. Baths containing from about 100 g./l. to about 500 g./l. are utilized.
  • the tendency for the electro deposition of chromium in a less bright condition increases as the CrO concentration is increased. It is diflicult to obtain mirror-bright deposits with baths having CrO concentrations in the high portion of the range. Such baths may be utilized at lower temperatures. Baths with CrO concentrations in the lower portion of the range yield mirror-bright deposits. The larger portion of the CrO concentration range may be utilized at all temperatures above 114 F. and below 140 F. The overall relationship of temperature, CrO concentration, and Ratio is defined by the area enclosed by the curves in Figure l.
  • the catalyst is a mixture of sulfate ions and complex fluoride ions.
  • a minimum of is sulfate and preferably at least 15% should be sulfate; the optimum baths contain at least 20% sulfate.
  • the sulfate should not be more than 85% of the total catalyst and preferably not more than 70%; the optimum baths contain less than 55% sulfate.
  • bright crack-free chromium can be electrodeposited at temperatures between 95 F. and 114 F., by utilizing a high Ratio. At 105 F., a Ratio of about 100:1 is the limiting Ratio, whereas the limiting Ratio at 95 F. is 150:1. For baths utilizing Ratios between those illustrated in the graphs, the limiting Ratios and temperatures may be found by interpolation from the plotted data. For greater clarity the overall curves of Figure 1 are illustrated separately in Figures 2, 3 and 4. The conditions under which bright crack-free chromium can be electroplated at a Ratio of 70:1 are delineated in Figure 2; at 100:1 in Figure 3; and at 150:1 in Figure 4.
  • Electroposits of bright crack-free chromium appreciably thicker than 0.00005 inch may often be in the order of 0.000 1 inch to 0.0002 inch, and in some cases as thick as .001 inch or more.
  • the shaded area located approximately in the upper central portion of each of the curves in Figures 2-4 define the limited conditions under which it is possible to electrodeposit bright crack-free chromium to a thickness of at least 0.0001 inch. As illustrated, at lower Ratios the area shifts to higher temperatures and decreases in size.
  • Electrodeposition of bright crack-free chromium be tween the temperatures of 105 F. and 135 F. is preferred. Within this range of temperatures, it is preferred to utilize CrO concentrations between about 150 g./l. and about 450 g./l. and a Ratio between about 80:1 to 130: 1. The relationship between these three variables must also fall within the areas defined by the curves in Figure 1.
  • Especially preferred conditions for electrodepositing bright crack-free chromium are those obtained within the rectangular area JKLM, at Ratios between about 85:1 and 120:1 utilizing baths having a CrO concentration between about 200 g./l. and 350 g./l. and plating at temperatures between about 118 F. and 130 F.
  • Chloride ion in the bath promotes the formation of cracks.
  • Baths containing more than about 0.05 g./l. of chloride ion cannot be used to electrodeposit bright crackfree chromium to a thickness of 0.00005 inch. Less than this amount may be tolerated when electrodeposition is carried out, for a given temperature and CrO concentration, at a Ratio selected from the high end of those allowable under the conditions specified. If it is desired to operate at a low Ratio (high catalyst ion content) selected from the allowable range, it is necessary to compensate for the presence of chloride by subtracting from the allowable catalyst ion content about fourteen times the amount of chloride ion present. When less than 0.005 g./l. of chloride is present, it may be ignored. It is preferable to operate with baths containing not more than 0.02 g./l. of chloride ion.
  • Chromium plating baths are frequently designated as chromic acid baths.
  • the chromic acid content of the bath is referred to as OrO (more accurately designated chromic anhydride).
  • the bath may be made up by supplying CrO in the form of chromic anhydride or in the form of compounds containing cations which do not adversely affect the bath characteristics. Such compounds include the chromates, d-ichromates, and polychromates of potassium, sodium, magnesium and calcium.
  • the CrO may also be added in the form of chromic acid and/or dichromic acid in solution. Where alkali metal cations are present the bath should not be neutralized in excess of to the dichromate end point.
  • Sulfite ions may be added in the form of sulfuric acid
  • fluoaluminate, fluotitanate, and fluozirconate anions may be added to the bath as salts, associated with such cations as sodium, potassium, calcium, strontium, ammonium, barium, etc. They may be formed in situ by the intro duction into a chromic acid bath of elements and/ or compounds which in the bath environment react to form the desired catalyst ion.
  • Bright crack-free electrodeposits are obtained under the conditions of this invention using suitable current densities.
  • the current densities vary between 0.5 a.s.i. (amperes per square inch) and 6 a.s.i., depending primarily on the plating temperature. These current densities are conventional and are described in Chromium Plating by Morrisset et 211., published by Robert Draper Ltd., 1954, pages 351-363 and particularly page 354.
  • a standard Hull Cell was used to determine the thickness to which bright chromium plate can be electrodeposited without cracking.
  • the cell is a box with an anode perpendicular to the sides and an inclined cathode.
  • Articles made of any of a variety of basis metals such as plain carbon steels, alloy steels including stainless steel, iron, copper and copper alloys, nickel and nickel alloys, zinc and zinc alloys, etc., may be plated with bright crack-free chromium.
  • the basis metal may be any metal, or an undercoat on a metal, that can be chromium plated.
  • the basis metal does affect the thickness of chromium which may be plated bright and crack-free to a certain extent. This is illustrated by the slightly greater thickness of bright crack-free chromium which can be deposited directly on steel than can be deposited directly on copper under the same process and bath conditions. The greater thickness attainable under the same conditions on the steel is attributed to the greater hardness of the basis metal and the support it is thus able to give the electrodeposit.
  • a process for electrodepositing bright crack-free chromium to a thickness of at least 0.00005 inch on a metal cathode comprising passing current from an anode to said cathode immersed in an aqueous chromium plating bath at a temperature between 95 F. and 140 F., said bath containing less than 0.05 g./l. of chloride ion and comprising essentially between 100 g./l.
  • a process for electrodepositing bright crack-free chromium to a thickness of at least 0.00005 inch on a metal cathode comprising passing current from an anode to said cathode immersed in an aqueous chromium plating bath at a temperature between F. and F., said bath containing less than 0.02 g./l. of chloride ion and comprising essentially between 150 g./l. and 450 g/l.
  • a process for electrodepositing bright crack-free chromium to a thickness of at least 0.00005 inch on a metal cathode comprising passing current from an anode to said cathode immersed in an aqueous chromium plating bath at a temperature between 118 F. and 130 F., said bath containing less than 0.02 g./l. of chloride ion and comprising essentially between 200 g./l. and 350 g./l.
  • a process for electrodepositing bright crack-free chromium to a thickness of at least 0.00005 inch on a metal cathode comprising passing current from an anode to said cathode immersed in an aqueous chromium plating bath at a temperature between 114 F. and F., said bath containing less than 0.02 g./l. of chloride ion and comprising essentially between 100 g./l. and 450 g./l.

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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 And Plating Baths Therefor (AREA)
  • Electroplating Methods And Accessories (AREA)
US833765A 1959-08-14 1959-08-14 Process for chromium plating Expired - Lifetime US2952590A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
US833765A US2952590A (en) 1959-08-14 1959-08-14 Process for chromium plating
DE19601446015 DE1446015B2 (de) 1959-08-14 1960-08-03 Verfahren zum galvanischen Abscheiden von glänzendem rißf^eien Chrom
GB27566/60A GB954033A (en) 1959-08-14 1960-08-09 Improvements in or relating to electrodepositing chromium
FR835691A FR1264979A (fr) 1959-08-14 1960-08-11 Procédé de chromage électrolytique
SE7748/60A SE309521B (cs) 1959-08-14 1960-08-11

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GB (1) GB954033A (cs)
SE (1) SE309521B (cs)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3079310A (en) * 1960-08-26 1963-02-26 James V Sheridan Electroplating zinc on aluminum
US3157585A (en) * 1959-12-18 1964-11-17 Gen Motors Corp Chromium plating
US3188186A (en) * 1959-12-18 1965-06-08 Gen Motors Corp Chromium plating
US3303113A (en) * 1963-10-18 1967-02-07 Udylite Corp Chromium plating
US3303114A (en) * 1964-01-10 1967-02-07 Udylite Corp Chromium plating
US3337430A (en) * 1963-08-05 1967-08-22 M & T Chemicals Inc Ultrahigh-speed chromium electrodeposition
US3418220A (en) * 1963-08-26 1968-12-24 Roggendorf Wilhelm Electrodeposition of chromium and duplex micro-crack chromium coatings
US3920527A (en) * 1968-02-03 1975-11-18 Schering Ag Self-regulating plating bath and method for electrodepositing chromium
US5028239A (en) * 1989-05-12 1991-07-02 Nalco Chemical Company Fuel dewatering additives
US20080173549A1 (en) * 2006-06-27 2008-07-24 Moline Andrew J Direct current chrome plating process and variant layered chrome product

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1815081A (en) * 1928-11-05 1931-07-21 Standard Sanitary Mfg Co Chromium plating
US1928284A (en) * 1932-01-14 1933-09-26 Colin G Fink Process of electrodepositing chromium
US2916424A (en) * 1957-11-07 1959-12-08 Metal & Thermit Corp Process for chromium plating

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1815081A (en) * 1928-11-05 1931-07-21 Standard Sanitary Mfg Co Chromium plating
US1928284A (en) * 1932-01-14 1933-09-26 Colin G Fink Process of electrodepositing chromium
US2916424A (en) * 1957-11-07 1959-12-08 Metal & Thermit Corp Process for chromium plating

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3157585A (en) * 1959-12-18 1964-11-17 Gen Motors Corp Chromium plating
US3188186A (en) * 1959-12-18 1965-06-08 Gen Motors Corp Chromium plating
US3079310A (en) * 1960-08-26 1963-02-26 James V Sheridan Electroplating zinc on aluminum
US3337430A (en) * 1963-08-05 1967-08-22 M & T Chemicals Inc Ultrahigh-speed chromium electrodeposition
US3418220A (en) * 1963-08-26 1968-12-24 Roggendorf Wilhelm Electrodeposition of chromium and duplex micro-crack chromium coatings
US3303113A (en) * 1963-10-18 1967-02-07 Udylite Corp Chromium plating
US3303114A (en) * 1964-01-10 1967-02-07 Udylite Corp Chromium plating
US3920527A (en) * 1968-02-03 1975-11-18 Schering Ag Self-regulating plating bath and method for electrodepositing chromium
US5028239A (en) * 1989-05-12 1991-07-02 Nalco Chemical Company Fuel dewatering additives
US20080173549A1 (en) * 2006-06-27 2008-07-24 Moline Andrew J Direct current chrome plating process and variant layered chrome product
EP2049709A4 (en) * 2006-06-27 2010-01-27 Enduro Ind Inc IMPROVED CONTINUOUS CHROMIUM PLATING METHOD AND MULTI-LAYER CHROME PRODUCT

Also Published As

Publication number Publication date
SE309521B (cs) 1969-03-24
DE1446015A1 (de) 1969-01-30
DE1446015B2 (de) 1970-11-05
GB954033A (en) 1964-04-02

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