US2640021A - Composition, bath, and process for chromium plating - Google Patents

Composition, bath, and process for chromium plating Download PDF

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Publication number
US2640021A
US2640021A US129128A US12912849A US2640021A US 2640021 A US2640021 A US 2640021A US 129128 A US129128 A US 129128A US 12912849 A US12912849 A US 12912849A US 2640021 A US2640021 A US 2640021A
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Prior art keywords
bath
chromic acid
chromium
composition
weight
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US129128A
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English (en)
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Passal Frank
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United Chromium Inc
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United Chromium Inc
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Priority to BE517665D priority Critical patent/BE517665A/xx
Application filed by United Chromium Inc filed Critical United Chromium Inc
Priority to US129128A priority patent/US2640021A/en
Priority to US129177A priority patent/US2664392A/en
Priority to FR1045610D priority patent/FR1045610A/fr
Priority to CH332151D priority patent/CH332151A/de
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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
    • C25D3/12—Electroplating: Baths therefor from solutions of nickel or cobalt
    • C25D3/14—Electroplating: Baths therefor from solutions of nickel or cobalt from baths containing acetylenic or heterocyclic compounds
    • C25D3/18—Heterocyclic compounds
    • 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

Definitions

  • This invention relates to a chromiumrplatin bathhaving exceptional plating. performance and a selferegulated catalyst acid radical contentsto compositions for maitingup such baths .andto a chromium plating. process and'provides im-. provernents therein.
  • an aqueous chromium plating bath (anda composition .for making up such a bath) is provided, which has a catalyst acid radical content supplied from strontium sulphate and potassium ,silicofluoride, these two compounds .heimg presentin excess';;of their solubilities in theqbath, and Which- ,hasa wide range of .ChI-OllliC acid concentrations, said bath giving superior performancaandbeing selfregulating as to the catalyst acid radical content insolution.
  • lhis invention also provides a chromium plating process, using modes of procedure in baths according to the present-inventionfor attaining (1-) fast deposition of thick, good quality bright chromium plate, (2) fast deposition of thick, good quality gray chromium plate and (3') high covering power in the deposition of bright chromium plate in usual-decorativeplate thicknesses.
  • the bath essentially consists of about 290 to 500 g/l.
  • Cl'Oa, strontium sulphate (SI'SOU present in. excess of its solubilityin the chromic acid solution and potassium silicofluoride (KaSi-Fe) also present in'excess of itssolubility in the chromic acid solution.
  • SI'SOU strontium sulphate
  • KaSi-Fe potassium silicofluoride
  • chromic acid of high purity is recommended, such as. chromic acidcontaining less than 0.1% by weight of sulphate'andno other catalyst acid radicals.
  • Chromic acidzor higher sulphate content can be used by first and: lysing for S04 and then adding approximately the stoichiornetric equivalent of strontium carbonate to form SrSCM with the S94 impurity, or byadding the stoiehiometric equivalent of barium carbonate, barium hydroxide, or barium chro mate for the SO;- in the chromic acid.
  • strontium sulphate Either a C. P. (chemically pure)" or a good: technical grade of strontium sulphate may be used.
  • One form or strontium sulphate comm-ercially available the mineral-Celestite which may-be also used-satisfactorily.
  • the SrSO; and KzSiFs instead of being added as such to the composition of matter or to the bath, may be added in the form of non-catalytic strontium and potassiumeornpounds and S04 and SlFt compounds which will interact solution to form STSO-4 and KzSiFs in amountswhichwill more than saturatethesolutions and provide aniundissolved excess or reservoir of SrSOrand KzSiFc from which S04 and SiFscatalystacid radicals lostfrom the bathin the course of operation will bereplenished.
  • non-catalytic strontium and p0:- tassiumg compounds are 51 60.3, Sr(QH)i, SIC'1'O4, etc. andKQI-l, KzCQspKoGrOr, I2GI'207.
  • SrSOe'and KaSiFe as such, orby adding CrOa, and a suitable strontium compound.
  • The. composition consistsoi chromic acid and enough SrSOiand .KzS'iE'c to provide as aminimum an undissolved excess of 81 504 andKzSiFt at any. desired bath concentration within the CrO's range of concentration, and at any desired temperature. within the operating range. of temperature.
  • composition will provide a bath solution saturated at 90 F. with SrSO4 and KzSiFs using this composition of matter in water to give CrOa concentrations of or near 500 g./l.
  • Example H Parts by weight CrOz, 95.3% 100 SrSOi, 1.4% 1.47 KzSiFs, 3.3% 3.5
  • the above composition will provide a bath solution saturated at 90 F. with SrSO4 and K2SiFs at minimum CIO3 concentration (200 g./l.), and an excess of SrSO4 and KzSiFs at higher CrOs concentrations, using this composition of matter.
  • Example III Parts by weight CrO3, 90.1% 100 SrSO4, 2.7% 3 KzSiFe, 7.2% 8
  • Example IV Parts by weight CrOs, 92.5% 100 SrSO4, 2.0% 2.16 KzSiFs, 5.5% 5.95
  • Example III A single composition, as Example III, has the advantage of having universal suitability throughout the full range of C1O3 concentration, but the composition such as Example II having lesser percentages of SrSOa and KzSiFe also are suitable for bath solutions of higher CrOa content.
  • Example I represents the minimum percentages of SrSO-r and KzsiFs usuable at the maximum CIOs concentration and hence the minimum percentage which can be used and still be within the range of CrO3 bath concentrations herein disclosed.
  • Example IV represents a composition in commercial use.
  • This bath makeup has a much higher degree of flexibility than any previously known chromium plating bath as regards the relationship of the catalyst acid radicals to the chromic acid content, and in addition the bath is self-regulating.
  • the efiect of the silicofluoride in the bath does not appear to be in arithmetic progression (additive) in relation to quantity added; that is, the catalytic effect of the SiF's in the present bath was found to have no definite or predictable effect by analogy to CrO3/SO4 current efficiency curves.
  • the effect of the silicofluoride also appears to be affected by the amount of S04 present, the amount of CIOs and the temperature of the bath.
  • Chromium plating baths containing silicofluoride went into considerable use some fifteen years ago, but have largely gone out of use, ,due probably to the difficulty of analysing them, the difficulty of maintaining uniform operating characteristics, and to the fact that deposits other than very thin deposits were pimply.
  • the deposits obtained by the use of the present inven tion are not pimply.
  • the deposits are smooth at all 0103 concentrations, have little or no tendency to tree at high plating speeds and have leveling action.
  • CIOs have a matte appearance, and are exceptionally smooth and free from nodules.
  • Deposits in decorative plate thicknesses are bright throughout the CrOa concentration range.
  • a bath according to the present invention containing SrSO; and KzSiFo present in excess of the solubilities thereof in the bath can vary over a wide range of CrOa concentrations, ranging from about 200 g./l. to 500 g./ with neither a wide nor a signficant variation in the current efficiencies at commonly used temperatures over a wide range of current densities (1-6 amperes per square inch at 130 F. for instance).
  • the current efliciences of baths within the present invention are generally higher than the best current efiiciencies obtainable with the CrO3/SO4 baths; and, within the CIO3 range, and, at separate parts of the CI'O: range, are found baths having superior performance in differing particulars.
  • Baths having optimum throwing power are obtained with a. CrOa content of about 450 g./l., with excellent throwing power at 400 to 500 g./l. ClOa.
  • CIOa concentration has been found to give optimum performance.
  • High plating speed results from high current efiiciency, and the feasible use of higher current densities.
  • the conventional Grog/S04 bath the
  • bath of the present invention within the 250 to 350 ClOs range (optimum 325 g./l. C1O3) has the advantage of considerably higher current efficiency and less tendency for treeing and has leveling action.
  • this gray matte deposit is an excellent plate, and, as with the definite leveling action of surface scratches or almanac ablasior platingzbrightgdirectly on stainlessstesl and: r'zinc 'base. idiewcastings.
  • the present. baths. glaze. chromium deposits which. arev less 'sensitivezto interruption of current. which in. the chromica acidi-zsu lphats.bath. ordinarily causes: objectionable .grayydeposits. or poor-adhesion; and havenza betteractivating ace: tion on .ni'clrel plate than. thsusuali chromi'c. acidsulphate bath.
  • The: plating bath .is one according' to: this; invention. having: a. vCrOa concentration of. 200110 350 g./l.- (3:25 g.,/l optimum-) Thick; bright deposits... (ll-.0011 or more by way r of example) may, be electroplated at. current: densities and bath temperatures;generallyused for chromium deposition (see: ModernElectroplating, The Electrochemical Society; 1:942 ⁇ . chapter on Chromium Plating, and particularly the charts on pages: 122; and 123).
  • Thchigher temperatures and: current densities; are usually employed for obtaining thick deposits; andrsuchare bestused. in thcprescnt. process for rapidly obtaining thick deposits, the advantage here being that current emci'encies better than are obtained inthe conventional CrOz/S'Os bath are obtained, and higher (0.001 or 'moreby way-of example) magi-tbs electroplated at current densities. and zbathctemq peratures; generally used, for: chromium deposition (see Modern: Electroplating; referred: to above) The higher temperatures and current. densitiesarousually employed iorobtainingthick deposits; and :such' are .best uscdsin'the preseut process.
  • the process for attaining high covering power in the deposition of bright chromium platc in usual decorative plate is carried outas-follows:
  • the plating bath isoneaccording to. the inven: tion, having a. CrOa concentration of. SEW-to 5'00.g./l. (400 to .500'g./l optimum)
  • Theldcposits are the kind used for .soicalled decorativebright plate and commonly are a. iew:hundredth'thou.-; sandths inch thick. These .decorativebright-idw posits.
  • the plating bath is: one accordingpto themsventio-n having a CrO-sxconcentrationvof. 4601' as optimum.
  • composition or matter for making'up anaqueous chromium plating bath comprising-essentiall-y' chromic acid-1' strontiumsulplrats and potassium sili'cofiuori de; there-"beingaboutwparts by weight of strontium sulphate and" about 8*- parts by weight potassium silicofluoride to'zl'fiil parts-by weight chromi'c acidi said composition when dissolved in waterbeing, adaptedto produce: a solution lia-ving a concentration. of 200' to' 250'0' gr/f. chromic'acid.
  • a composition of matter for making up an aqueous chromium plating bath comprising essentially chromic acid, strontium sulphate and potassium silicofiuoride, there being about 2.16 parts by weight strontium sulphate and about 5.95 parts'by weight potassium s'ilicofiuoride to 100 parts by weight chromic acid, said composition when dissolved in water being adapted to produce a. solution having a concentration of 200 to 500 g./l. chromic acid,
  • An aqueous bath for chromium plating consisting essentially of 200 to 500 -g./l, chromic acid, and strontium sulphate and potassium silicofi-uoride present each in amounts in excess of the solubility thereof in the chromic acid solution.
  • An aqueous bath for chromium plating consisting essentially of 400 to 500 g./l. chromic acid, and strontium sulphate and potassium silicofluoride present each in amounts in excess of the solubility thereof in the chromic acid solution.
  • An aqueous bath for chromium plating consisting essentially of 250 to 350 g./l. chromic acid. and strontium sulphate and potassium silicoiluoride present each in amounts in excess of the solubility thereof in the chromic acid solution.
  • a process of electrodepositing thick, bright chromium of good quality consisting essentially of passing current from an anode to an articlec-athode immersed in a bath consisting essentially of 200 to 350 g./l. C103 and strontium sulphate and potassium silicofluoride present in the bath each in excess of its solubility therein.
  • a process of electroclepositing chromium of good quality consisting essentially of 'passing'current from an anode to an article-cathode immersed in a bath consisting essentially of 350 to 500g./l.
  • Ci'Os and strontium sulphate and potassium silicofiuoride present in the bath each in excess of its solubility therein.
  • a process of electrodepositing bright chromium in plating barrels consisting essentially of passing current from an anode to an articlecathode immersed in a bath consisting of 450 gQ/l. ClOs and strontium sulphate and potassium sili'cofluoride present in the bath each in excess of its solubility therein.
  • a composition of matter for making up and maintaining aqueous baths for chromium plating comprising essentially chromic acid, strontium sulphate, and potassium silicofluoride, the strontium sulphate content being in excess of about 0.61 part by weight to 100 parts by weight of chromic acid and the potassium silicofiuoride content being in excess of about 1.74 parts by weight to 100 parts by weight of chromic acid, said composition when dissolved in water to produce a solution having 200 to 500 g./l.
  • composition of matter for making up and maintaining aqueous baths for chromium plating comprising essentially chromic acid, strontium sulphate, and potassium silicofiuoride, the
  • strontium sulphate content being in excess of about 0.61 part by weight to parts by weight of chromic acid and the potassium silicofiuoride content being in excess of about 1.74 parts by weight to 100 parts by weight of chromic acid, said composition when dissolved in water being adapted to produce a solution having excess undissolved amounts of strontium sulphate and potassium silicofluoride.
  • a composition of matter for making up and maintaining aqueous baths for chromium plating comprising essentially chromic acid, strontium sulphate, and potassium silicofluoride.
  • the strontium sulphate content being in excess of about 0.61 part by weight to 100 parts by weight of chromic acid and the potassium silicofiuoride content being in excess of about 1.74 parts by weight to 100 parts by weight of chromic acid.
  • a composition of matter for making up and maintaining an aqueous chromium plating bath comprising essentially chromic acid, strontium sulphate and potassium silicofluoride. there being at least about 1.47 parts by weight of strontium sulphate and at least about 3.5 parts by weight of potassium silicofiuoride to 100 parts by weight 01' chromic acid, said composition when dissolved in water being adapted to produce a solution having a concentration of 200 to 500 g./l. o1 chromic acid.
  • a composition of matter for making up and maintaining an aqueous chromium plating bath comprising essentially chromic acid, (1) a bathsoluble compound containing catalytic sulphate radical, (2) a bath-soluble strontium compound of a non-catalytic anion, the amount of said strontium compound being stoichiometrically equivalent to the amount of said sulphate compound so as to react therewith in said bath to form strontium sulphate, (3) a bath-soluble compound containing catalytic silicofiuoride radical, and (4) a bath-soluble potassium compound of a non-catalytic anion, the amount of said potassium compound being stoichiometrically equivalent to the amount of said silicofluoride compound so as to react therewith in said bath to form potassium silicofluoride, the said four compounds being present in such quantities to form at least about 0.61 part by weight strontium sulphate to 100 parts by weight of chromic acid and at least about 1.74 parts by weight of potassium silico

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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)
US129128A 1949-11-23 1949-11-23 Composition, bath, and process for chromium plating Expired - Lifetime US2640021A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
BE517665D BE517665A (en, 2012) 1949-11-23
US129128A US2640021A (en) 1949-11-23 1949-11-23 Composition, bath, and process for chromium plating
US129177A US2664392A (en) 1949-11-23 1949-11-23 Nickel plating
FR1045610D FR1045610A (fr) 1949-11-23 1950-11-22 Bains de chromage dont la teneur en radical acide catalyseur s'ajuste automatiquement, compositions pour ces bains et procédé de chromage
CH332151D CH332151A (de) 1949-11-23 1953-02-12 Wässriges chromhaltiges Bad und Verfahren zu seiner Herstellung

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BE (1) BE517665A (en, 2012)
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FR (1) FR1045610A (en, 2012)

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2787589A (en) * 1954-08-12 1957-04-02 Metal & Thermit Corp Chromium plating
US2787588A (en) * 1954-08-12 1957-04-02 Metal & Thermit Corp Chromium plating
US2800443A (en) * 1955-07-26 1957-07-23 Metal & Thermit Corp Method of chromium plating
US2800437A (en) * 1955-07-26 1957-07-23 Metal & Thermit Corp Chromium plating
US2800438A (en) * 1955-07-26 1957-07-23 Metal & Thermit Corp Chromium plating
US2800436A (en) * 1955-07-26 1957-07-23 Metal & Thermit Corp Method of chromium plating
US2841540A (en) * 1955-10-28 1958-07-01 Diamond Alkali Co Chemical composition for chromium plating
US2841541A (en) * 1955-10-28 1958-07-01 Diamond Alkali Co Chemical composition for chromium plating
US2847373A (en) * 1953-11-12 1958-08-12 Wean Engineering Co Inc Electroplating zinc on basis metal
US2950234A (en) * 1958-02-26 1960-08-23 Metal & Thermit Corp Chromium plating process and bath
US3257294A (en) * 1961-08-10 1966-06-21 Dehydag Gmbh Acid metal electroplating process and baths
NL6805383A (en, 2012) * 1967-04-17 1968-10-18

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3108933A (en) * 1961-02-28 1963-10-29 M & T Chemicals Inc Process and composition for chromium plating

Citations (6)

* 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
US1844751A (en) * 1925-08-12 1932-02-09 United Chromium Inc Process of electrodepositing chromium
US1864014A (en) * 1927-01-03 1932-06-21 Dwight T Ewing Chromium plating process
US1928284A (en) * 1932-01-14 1933-09-26 Colin G Fink Process of electrodepositing chromium
US2042611A (en) * 1932-02-03 1936-06-02 United Chromium Inc Control of chromium plating solutions
GB566218A (en) * 1943-01-08 1944-12-19 James Lewis Pugh Macnair Improvements in the electrodeposition of chromium

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1844751A (en) * 1925-08-12 1932-02-09 United Chromium Inc Process of electrodepositing chromium
US1864014A (en) * 1927-01-03 1932-06-21 Dwight T Ewing Chromium plating process
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
US2042611A (en) * 1932-02-03 1936-06-02 United Chromium Inc Control of chromium plating solutions
GB566218A (en) * 1943-01-08 1944-12-19 James Lewis Pugh Macnair Improvements in the electrodeposition of chromium

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2847373A (en) * 1953-11-12 1958-08-12 Wean Engineering Co Inc Electroplating zinc on basis metal
US2787588A (en) * 1954-08-12 1957-04-02 Metal & Thermit Corp Chromium plating
US2787589A (en) * 1954-08-12 1957-04-02 Metal & Thermit Corp Chromium plating
US2800443A (en) * 1955-07-26 1957-07-23 Metal & Thermit Corp Method of chromium plating
US2800437A (en) * 1955-07-26 1957-07-23 Metal & Thermit Corp Chromium plating
US2800438A (en) * 1955-07-26 1957-07-23 Metal & Thermit Corp Chromium plating
US2800436A (en) * 1955-07-26 1957-07-23 Metal & Thermit Corp Method of chromium plating
US2841540A (en) * 1955-10-28 1958-07-01 Diamond Alkali Co Chemical composition for chromium plating
US2841541A (en) * 1955-10-28 1958-07-01 Diamond Alkali Co Chemical composition for chromium plating
US2950234A (en) * 1958-02-26 1960-08-23 Metal & Thermit Corp Chromium plating process and bath
US3257294A (en) * 1961-08-10 1966-06-21 Dehydag Gmbh Acid metal electroplating process and baths
NL6805383A (en, 2012) * 1967-04-17 1968-10-18
US3502549A (en) * 1967-04-17 1970-03-24 Ugine Kuhlmann Method for the protection of zirconium and zirconium-base alloys

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FR1045610A (fr) 1953-11-30
CH332151A (de) 1958-08-31

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