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EP0073221B1 - Hochgeschwindigkeitsüberzug einer chromlegierung - Google Patents

Hochgeschwindigkeitsüberzug einer chromlegierung Download PDF

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Publication number
EP0073221B1
EP0073221B1 EP82900730A EP82900730A EP0073221B1 EP 0073221 B1 EP0073221 B1 EP 0073221B1 EP 82900730 A EP82900730 A EP 82900730A EP 82900730 A EP82900730 A EP 82900730A EP 0073221 B1 EP0073221 B1 EP 0073221B1
Authority
EP
European Patent Office
Prior art keywords
chromium
cathode
iron
nickel
plating solution
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
Application number
EP82900730A
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English (en)
French (fr)
Other versions
EP0073221A4 (de
EP0073221A1 (de
Inventor
Glenn R. Schaer
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.)
Battelle Development Corp
Original Assignee
Battelle Development 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 Battelle Development Corp filed Critical Battelle Development Corp
Priority to AT82900730T priority Critical patent/ATE17752T1/de
Publication of EP0073221A4 publication Critical patent/EP0073221A4/de
Publication of EP0073221A1 publication Critical patent/EP0073221A1/de
Application granted granted Critical
Publication of EP0073221B1 publication Critical patent/EP0073221B1/de
Expired legal-status Critical Current

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Classifications

    • 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
    • C25D3/56—Electroplating: Baths therefor from solutions of alloys
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
    • C25D5/04—Electroplating with moving electrodes

Definitions

  • This invention relates to the high-speed plating of chromium alloys.
  • Extensive use of relatively scarce materials, such as nickel and chromium, in corrosive environments may be reduced by an acceptable plating process which may form a corrosion-resistant coating of, say, 25 ⁇ m of a chromium alloy, on an inexpensive substrate, such as steel or brass.
  • a bright, decorative coating of chromium alloy is also valued in some uses.
  • US-A-3,917,517 discloses hypophosphite containing chromium alloys electroplating baths providing chromium platings at current densities of up to 100 A/dm 2.
  • US-A-4,142,948 discloses chromium electroplating baths containing trivalent chromium and operating at pH below 5 and at current densities up to 100 Aldm 2 due to the presence, as additives, of amino- or hydroxy-substituted carboxylic acids.
  • the invention disclosed in claim 1 is a method for high-rate plating of chromium alloy from an electrolyte solution containing divalent and trivalent chromium ions, ions of iron and, optionally, ions of nickel and/or cobalt as additional alloying constitutents.
  • the high-rate plating is carried out at a current density of at least about 75 Aldm 2 (preferably at least about 150 A/dm2), a pH of between about 0.5 and 2.0 and with relative motion between the cathode and the plating solution of at least about 1 m/sec (preferably 1-8 m/sec).
  • Deposits of composition 5-80% (by weight) chromium, 20-95% iron and 0-50% nickel are preferably formed by electrolyzing an electrolyte solution having metal ion concentrations of 20 g/I to saturation divalent/trivalent chromium, 1-50 g/I iron and 0-50 g/I nickel.
  • Complexing anions of sulfuric, sulfamic, hydrochloric, phosphoric and boric acids are preferred in the electrolyte.
  • a porous barrier is typically positioned around the cathode to prevent migration of anode oxidation reaction products to the cathode where they would otherwise oxidize the divalent/trivalent chromium to the hexavalent state.
  • the inventor has also discovered that the best deposits of chromium alloy may be obtained by strictly maintaining the free acid of the electrolyte within a narrow range corresponding to a pH of about 1.7 to 1.8. Very accurate metering must be used to monitor pH or a titration may be necessary to establish the amount of free-acid in the bath.
  • the invention is a method for electroplating a chromium alloy containing iron and, optionally, nickel and/or cobalt.
  • the alloy compositions preferably fall in the range (by weight) of 5-80% chromium, 20-95% iron and 0-50% total nickel and/or cobalt. We have found that alloys outside of this range may be plated according to the invention, but for the desired corrosion-resistance of the coatings, at least about 5-10% chromium is necessary. Chromium and nickel contents above the preferred range unduly raise the cost of the alloys and are, therefore not preferred. Chromium-nickel-iron alloys are the preferred coating compositions and, in particular, the 300 and 400 classes of stainless steels are preferred.
  • Type 304 stainless (18% Cr-8% Ni-2% Mn-balance Fe) is one desirable composition.
  • examples and discussion regarding chromium-iron-nickel alloys are intended to include alloys wherein cobalt may be substituted, as known in the art, for all or a portion of the nickel.
  • Other impurities which may enter the deposit from the anode, for example, may also be deposited without harm.
  • Manganese, silicon and copper are examples.
  • the alloy coating is formed on a conventional cathode surface of, for example, steel, iron, aluminum, brass or copper.
  • Insoluble anodes such as made from lead, may be used, although soluble alloy anodes of iron and chromium have been most useful in the inventive process.
  • the electrolyte is a divalent/trivalent chromium salt solution preferably containing 20 g/I to saturation of chromium ions, 1-50 g/I iron ions and a total of 0-50 g/I of nickel and/or cobalt ions.
  • the trivalent chromium may be converted to the divalent form and vice versa so that the exact ratio thereof was not clearly identified. Therefore, the two species are believed to both be present and necessary, and the reference to trivalent chromium is also intended to include the lower specie which coexists in the bath. Excess divalent form can adversely affect nickel deposition because it tends to reduce the nickel ions to the metal, resulting in precipitation or plating on the walls, etc. of the cell.
  • Some electrolyte solutions require a period of stabilization before yielding superior product. This may be due to a need to produce some particular minimum quantity of divalent chromium in the bath.
  • the pH of the electrolyte has been found to be a critical factor in depositing thick, bright and semi-bright coatings. Within the pH range of 0.5-2.0, good chromium alloy coatings can be deposited which are matte textured, but which are still useful in some applications of corrosion and wear resistance. These coatings are generally limited in thickness to about 12 to 25 ⁇ m. Thicker coatings tend to crack or peel as a result of increasing internal stresses.
  • the acidity range is so narrow that difficulty may be encountered in accurately measuring and maintaining it throughout the solution.
  • sensitive instruments exist for measuring the pH, and in practice a pH meter might be used for convenience.
  • We define the "free acid” content as the quantity of 0.1 N NaOH solution needed to bring a 1.0 ml aliquot of electrolyte to pH 3.5.
  • the preferred range of free acid using this titration method is about 0.5 ml-1.5 ml NaOH, corresponding to the pH of about 1.8-1.7, respectively.
  • the temperature of the plating solution is preferably in the range of 25­75°C.
  • the most critical operating parameters to obtaining crack-free, adherent coatings are the current density and the agitation or solution flow.
  • the acidity and solution flow particularly affect the deposition rate and the density of the coating, but acidity does not significantly affect composition of the deposit except at very low pH where nickel and iron plating reactions decrease in efficiency. Composition is more particularly affected by the current density and the electrolyte composition.
  • the composition of the deposit can be made to more closely-approximate the electrolyte composition than in prior plating methods, especially for the iron-chromium binary alloy from sulfamate solutions, even for high-chromium deposits.
  • Current densities for the inventive method are at least 75 amps/dm 2 , but preferably within the range of about 150-400 amps/dm 2 .
  • the higher current densities favor deposition of chromium over the iron or other metals and are necessary for obtaining the high-chromium alloys from the trivalent chromium solutions.
  • the chromium, iron and particularly the nickel or cobalt would be hard to plate in dense, adherent deposits were it not for high agitation or solution flow rates in conjunction therewith.
  • Turbulent action near the cathode resulting from cathode motion or solution flow, creates a transport mechanism for replacing depleted electrolyte with cation-rich solution.
  • Relative motion of at least 1 m/sec between the cathode surface and the plating solution is generally sufficient to create the turbulent conditions necessary for good deposits.
  • velocities of 1-80 m/sec could be used, but 1-8 m/sec is preferred.
  • composition comparable to bath composition
  • an alloy may be deposited having a composition ratio virtually the same as the metal ratio in the electrolyte, despite the difference in reduction potentials of the chromium and iron plating reactions.
  • an iron and chromium sulfamate electrolyte was made by dissolving the metals in an acid solution of sulfamic acid.
  • concentrations were 0.25 molar chromium (13 g/I Cr) and 0.75 molar iron (42 g/I Fe).
  • the current density was 160 amps/dm 2 and the rod-shaped steel cathode was rotated with a 2.5 m/sec surface velocity.
  • a lead anode was utilized and was isolated from the cathode by a porous alumina diaphragm. Temperatures were between about 37° and 49°C.
  • Sample 43F used a 10 minute deposition at pH 1.6 while sample 52 plated for 5 minutes at pH 1.7. In both cases the alloy composition weight ratio was substantially the same as the electrolyte, 72 Fe-28 Cr and 75 Fe-25 Cr ( ⁇ 3%) respectively. Cathode efficiencies were about 26-27%.
  • the lead anode showed signs of dissolving in the sulfamate bath.
  • a platinum or graphite anode or, preferably, a soluble anode could be used.
  • Manganese content in the alloy samples was less than 1% and is, therefore, not reported.
  • the chromium content in the alloy deposit is dependent on several operating conditions, including current density, agitation, pH, ratio of metal ions in solution and type of anion used to complex the metal ions. Comparing samples 13A and 14C, the difference in pH is the major variable and the chromium content is higher when the pH was lower (higher acid content). This is reasonable because the coulombic (cathode) efficiency for plating both iron and nickel is known to be poor at the lower pH values.
  • Samples 18D and 18F were plated under similar conditions with the exception of current density. The results show that the higher current density used for sample 18F resulted in a higher chromium content.
  • Temperature also affects the percentage of chromium in a deposit. Comparing samples 19E and 19L, the temperature was increased from 62 to 65C and the chromium content in the deposit was reduced from 21 to 8 percent. In general, the temperature does not appear to be quite this critical, but higher temperatures do not favor the chromium deposition.
  • the alloy deposit may be pushed to a higher chromium and a lower nickel content.
  • Sample 202/98-14e was plated in a conventional cell using a soluble Type 304 stainless steel anode and a solution of:
  • the temperature was 62°C and the pH was 1.4.
  • a 125 ⁇ m coating was applied in 30 minutes.
  • the relatively dense coating was matte textured on the surface but otherwise generally crack free and had a composition of 16 Cr-21 Ni-63 Fe.
  • Iron-chromium alloy coatings were deposited from an electrolyte solution of the chromium (56 g/I) and iron (52 g/I) chloride salts at about 30°C.
  • the apparatus of Example 1 was used (with the exception of a soluble 30/70 chromium-iron anode) to plate the alloy coatings shown in Table 2.
  • Cathode efficiency is conventionally defined as the percentage of the applied current used to deposit the chromium alloy.
  • Samples 96B, 96C and 96D were marginally cracked but were otherwise suitable coatings similar to conventional hard chromium plates deposited in catalyzed chromic acid solutions. These cracks in the deposits may not be detrimental where wear resistance in the main property desired in a coating.
  • a 30/70 chromium-iron anode was again used in a sulfate solution to plate alloy coatings on a copper-coated, steel-ring cathode.
  • the plating solution compositions were as follows:

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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)

Claims (7)

1. Verfahren zur galvanischen Hochgeschwindigkeitsablagerung eines Chromlegierungsüberzuges auf einer Kathode, bei der man eine wäßrige, galvanische Lösung, die Eisenionen und zwei- und dreiwertige Chromionen enthält, mit einer Stromdichte von wenigstens etwa 75 Aldm2 und einem pH-Wert zwischen etwa 0,5 und 2,0 elektrolysiert, dadurch gekennzeichnet, daß die relative Bewegung zwischen der Kathode und der wäßrigen, galvanischen Lösung an der Kathodenoberfläche wenigstens etwa 1 m/sek beträgt.
2. Galvanisches Ablagerungsverfahren nach Anspruch 1, dadurch gekennzeichnet, daß die elektrolysierte wäßrige, galvanische Lösung weiters zusätzliche Metallegierungsionen enthält, die aus Nickel und/oder Kobalt ausgewählt sind.
3. Galvanisches Ablagerungsverfahren nach Anspruch 2, zur Herstellung eines Chromlegierungsüberzuges, der im wesentlichen aus 5 bis 80 Gew.-% Chrom, 20 bis 95 Gew.% Eisen und 0 bis 50 Gew.% Nickel besteht, dadurch gekennzeichnet, daß eine wäßrige, galvanische Lösung elektrolysiert wird, die von etwa 20 g/I bis zur Sättigung zwei- und dreiwertige Chromionen, von eta 1 bis 50 g/I Eisenionen und von etwa 0 bis 50 g/I Nickelionen enthält.
4. Galvanisches Ablagerungsverfahren nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß die wäßrige galvanische Lösung elektrolysiert wird, die weiters komplexbildende Anionen von Mineralsäuren enthält, die aus den Schwefelsäuren, der Sulfaminsäure, der Salzsäure, den Phosphorsäuren und den Borsäuren ausgewählt werden.
5. Galvanisches Ablagerungsverfahren nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß der pH-Wert der wäßrigen, galvanischen Lösung zwischen etwa 1,7 und 1,8 gehalten wird.
6. Galvanisches Ablagerungsverfahren nach Anspruch 5, bei dem die Anode unlöslich ist, weiters dadurch gekennzeichnet, daß die Oxidation des zwei- und dreiwertigen Chroms nahe der Kathode verhindert wird, indem man die Bewegung der Oxidationsmittel zur Kathode unterbindet.
7. Galvanisches Ablagerungsverfahren nach Anspruch 1, dadurch gekennzeichnet, daß die Stromdichte zwischen etwa 150 und 400 A/dm2 ist.
EP82900730A 1981-03-09 1982-01-21 Hochgeschwindigkeitsüberzug einer chromlegierung Expired EP0073221B1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT82900730T ATE17752T1 (de) 1981-03-09 1982-01-21 Hochgeschwindigkeitsueberzug einer chromlegierung.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US24166381A 1981-03-09 1981-03-09
US241663 1981-03-09

Publications (3)

Publication Number Publication Date
EP0073221A4 EP0073221A4 (de) 1983-01-14
EP0073221A1 EP0073221A1 (de) 1983-03-09
EP0073221B1 true EP0073221B1 (de) 1986-01-29

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP82900730A Expired EP0073221B1 (de) 1981-03-09 1982-01-21 Hochgeschwindigkeitsüberzug einer chromlegierung

Country Status (5)

Country Link
EP (1) EP0073221B1 (de)
JP (1) JPS58500253A (de)
CA (1) CA1195645A (de)
DE (1) DE3268722D1 (de)
WO (1) WO1982003095A1 (de)

Families Citing this family (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB8409073D0 (en) * 1984-04-07 1984-05-16 Inter Metals & Minerals Sa Electrodeposition of chromium &c
JPS6156294A (ja) * 1984-08-27 1986-03-20 Nippon Kokan Kk <Nkk> クロム合金メツキ浴
JP2002206189A (ja) * 2000-12-28 2002-07-26 Nippon Platec Co Ltd 鉄系下地金属へのクロムメッキ方法
WO2007115030A1 (en) 2006-03-31 2007-10-11 Atotech Deutschland Gmbh Crystalline chromium deposit
FR2901496A1 (fr) * 2006-05-24 2007-11-30 Fivalec Electronic Sarl Alliage pour revetir des pieces de soudage et son procede d'obtention
CN101849041B (zh) 2007-10-02 2013-01-23 爱托特奇德国股份有限公司 结晶态铬合金沉积层
US7780840B2 (en) * 2008-10-30 2010-08-24 Trevor Pearson Process for plating chromium from a trivalent chromium plating bath
FI129420B (en) * 2020-04-23 2022-02-15 Savroc Ltd AQUATIC ELECTRIC COATING BATH
CN111910226A (zh) * 2020-07-15 2020-11-10 南昌航空大学 一种无裂纹Fe-Cr合金镀层及其制备方法和应用

Family Cites Families (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2766196A (en) * 1953-11-09 1956-10-09 Yoshida Tadashi Process for the electrodeposition of iron-chromium alloys
US2990343A (en) * 1955-02-11 1961-06-27 William H Safranek Chromium alloy plating
US2822326A (en) * 1955-03-22 1958-02-04 Rockwell Spring & Axle Co Bright chromium alloy plating
US2927066A (en) * 1955-12-30 1960-03-01 Glenn R Schaer Chromium alloy plating
US2938842A (en) * 1959-03-16 1960-05-31 Yawata Iron & Steel Co Electrodeposition of fe-cr alloy
GB1482747A (en) * 1973-10-10 1977-08-10 Bnf Metals Tech Centre Chromium plating baths
GB1455580A (en) * 1973-12-13 1976-11-17 Albright & Wilson Electrodeposition of chromium
JPS539236A (en) * 1976-07-13 1978-01-27 Nippon Piston Ring Co Ltd High speed chromium plating method
JPS53106348A (en) * 1977-02-28 1978-09-16 Toyo Soda Mfg Co Ltd Electrolytic bath for chromium plating
AU513298B2 (en) * 1978-06-02 1980-11-27 International Lead Zinc Research Organization Inc. Electrodeposition of black chromium

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
J.K. Dennis, "Nickel and chromism plating", pages 98-99, 1972 *

Also Published As

Publication number Publication date
JPS58500253A (ja) 1983-02-17
DE3268722D1 (en) 1986-03-13
WO1982003095A1 (en) 1982-09-16
EP0073221A4 (de) 1983-01-14
EP0073221A1 (de) 1983-03-09
CA1195645A (en) 1985-10-22

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