US3411995A - Process and product for plating on cast,malleable,carburized and carbonitrided irons - Google Patents

Process and product for plating on cast,malleable,carburized and carbonitrided irons Download PDF

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Publication number
US3411995A
US3411995A US439987A US43998765A US3411995A US 3411995 A US3411995 A US 3411995A US 439987 A US439987 A US 439987A US 43998765 A US43998765 A US 43998765A US 3411995 A US3411995 A US 3411995A
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film
zinc
plating
per gallon
cyanide
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US439987A
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Edward B Saubestre
Theophil J Wieczorek
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MacDermid Enthone Inc
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Enthone Inc
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Priority to US439987A priority Critical patent/US3411995A/en
Priority to ES0323665A priority patent/ES323665A1/es
Priority to GB10063/66A priority patent/GB1145352A/en
Priority to SE3118/66A priority patent/SE323562B/xx
Priority to DE19661521929 priority patent/DE1521929C/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
    • C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
    • C25D5/34—Pretreatment of metallic surfaces to be electroplated
    • C25D5/36—Pretreatment of metallic surfaces to be electroplated of iron or steel
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
    • C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
    • C23C22/07—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing phosphates
    • C23C22/08—Orthophosphates

Definitions

  • R is H, -CO-CH -PO(OH) or --SO (OH), R is H or H(CH n is 1-2 and m is 1-4, and optionally an organic thio compound as corrosion inhibitor, the aqueous acid solution having a pH of up to 3.0 inclusive and being at room temperature or an elevated temperature up to 180 F., for a time sufficient to form the ferrous surface a thin continuous phosphate-containing film.
  • the thus-coated ferrous metal surface is then zinc electroplated in a cyanide zinc electroplating bath.
  • the present invention relates to an improved process for plating on ,cast, malleable, carburized and carbonitrided irons and to the resulting product.
  • cast iron includes gray irons, white cast irons, chilled (white face) cast irons and malleable irons.
  • Cast irons are alloys of iron, carbon and silicon in which more carbon is present than can be retained in solid solutions in austenite at the eutectic temperature.
  • the carbon content of cast irons is generally 1.5 to 4.5 percent.
  • Gray iron is the most widely used of the cast irons.
  • gray iron covers a series of eutectiferous alloys that offer a wide selection of mechanical properties, with the composition and processing so adjusted that the matrix structure is largely pearlite (a lamellar mixture of ferrite and cementite) with many graphitic flakes dispersed throughout. This presence of graphite flakes imparts the characteristic gray fracture of these alloys.
  • austenitic cast irons which contain sufficient amounts of alloying elements to lower the eutectoid transformation temperature to such an extent that austenite is retained as the matrix at room temperature, with graphite flakes dispersed throughout the structure. (Nickel is commonly used for this purpose.) 'In white cast iron, almost all of the carbon is in the combined form.
  • Malleable cast iron refers to White cast irons which have been heat treated so as to decompose most of the cementite into ferrite and free (or temper) carbon which is usually in the form of nodularized graphite particles.
  • Carburizing is the process of increasing the carbon content of the ferrous surface by exposing it at high temperature to an atmosphere of CO +CO with or without hydrocarbon gases so that when quenched, the surface portion thus carburized will be substantially harder than the underlying metal.
  • a typical carburized steel may have 1.5 percent C in the surface layers.
  • the combined proc esses of carburizing and hardening have long been known as case hardening.
  • Carbonitriding is that specific example of carburizing in which ammonia and hydrocarbon gases are decomposed to provide simultaneous addition of carbon and nitrogen to the surface being case hardened.
  • Another example of a similar operation is cyaniding, in which molten potassium cyanide is decomposed to achieve the same ends.
  • the electroplater is faced with a similar problem: the surface of the metal to be plated contains free carbon, generally in the form of graphite.
  • the production of a satisfactory plate on cast irons depends upon a high cathodic hydrogen overvoltage on the iron being plated.
  • the graphite or free carbon on the surface presents two problems; it leads to undissolved smuts on the surface of the part to be plated in the conventional cleaning cycles frequently employed prior to plating and it lowers significantly the hydrogen overvoltage at the site of such graphitic inclusions. The latter effect can be quite serious when plating such objects with zinc from cyanide solutions. In such solutions, standard electrode potentials favor the cathodic reduction of hydrogen rather than zinc.
  • Free carbon and graphite deposits occur to a large extent in ordinary untreated cast irons and in other cases are produced by heat treatment, such as case hardening to improve the strength and resistability of the product.
  • discrete particles of carbon and/or graphite on the surface either occurring naturally or by the processing of the iron by carburizing or carbonitriding lower the hydrogen overvoltage values to such an extent that the evolution of hydrogen and deposition of a continuous plate on the iron surface is either severely affected or precluded completely.
  • ASTM Recommended Practice B320-60 summarizes current thinking regarding methods for preparation of malleable, gray, nodular and white iron castings for electroplating.
  • the preparation cycle recommended by ASTM involves four basic steps:
  • ASTM recommends the following cycle:
  • the critical step is the acid pickling step. If the subsequent electroplating is to be done under conditions causing sufliciently high hydrogen overvoltage (most acid solutions, and such alkaline solution as copper, cadmium, or tin), a brief dip (less than seconds) in a room temperature solution of percent (vol.) HCl (37 percent by weight) or 5 to 10 percent (vol.) H SO (98 percent by weight) is usually adequate. If the plating is to be done in an alkaline solution of low hydrogen overvoltage such as cyanide zinc, however, anodic treatment in acid to remove surface carbon is preferred.
  • an alkaline solution of low hydrogen overvoltage such as cyanide zinc
  • step 5 of the above cycle we have previously recommended the use of a solution containing, for example, about 10 oz. per gallon of an iron chelate, such as EDTA (ethylenedia-minetetraacetic acid), gluconate, oxalate, citrate, heptogluconate and the like, 22 oz. per gallon of casutic soda or potash, and 16 oz. per gallon of cyanide of soda or potash.
  • an iron chelate such as EDTA (ethylenedia-minetetraacetic acid)
  • a final purpose of the invention is to reveal an improved method of preparing cast iron surfaces whereby such substrates may be coated conveniently with a readily solderable, sacrificially protective corrosion resistant coating using the baths of US. 2,884,350 and 2,898,274, for example.
  • the film which we have found to be so desirable is a phosphate film produced from an aqueous acidic deoxidizing solution containing phosphate ions, together with nonionic, cationic surfactants or both.
  • the film-forming solution may be used in one of three ways in the preparation for plating procedure for the substrates which are the subject of our invention. First, it may be used after cleaning as the sole deoxidizing step prior to plating, in which case the disclosed solution acts both to deoxidize and to form the desired film. Secondly, in the case of heavily oxidized substrates, it may be used after cleaning and acid pickling such as recommended in the ASTM procedure previously noted. Thirdly, and optimally, it may be used following alkaline descaling as described in the recently improved methods noted above.
  • film-forming materials containing phosphates, surfactants and various other additives has previously been employed as a pre-cleaning step followed by the usual conventional methods for preparing such iron substrates for subsequent plating.
  • These prior art procedures involve the immersion of the iron article in an acidic solution containing phosphates and the part is further treated in either an alkaline descaler or a combination of alkaline electrocleaners.
  • Such materials are completely removed from the surface by a pickling treatment or otherwise prior to the application of the usual plating procedures to the film free surface of the iron.
  • the prior art applications of such film-forming baths did not result in a surface which could be satisfactorily electroplated, particularly to the application of cyanide zinc plate to the ferriferous surface of the type which are the subject of this invention.
  • the present invention involves the application of a thin continuous film to the surface of the iron to be plated which remains in place on the ferriferous surface and the metal from the electrolyte is deposited directly on the thin filmed surface of the iron. Surprisingly, the result is that high overvoltage is maintained and a remarkably attractive and firmly adherent electroplate results.
  • the film-forming solution contains one or more nonionic or cationic surfactants which will preferentially wet the surfaces being prepared for plating.
  • nonionic or cationic surfactants which will preferentially wet the surfaces being prepared for plating.
  • solvents it may be advantageous in the case of substrates containing unusually large amounts of graphitic-bearing particles on the surface to add solvents to help sweep away all particles from the surface.
  • solvents should be miscible in all desired proportions with the acidic medium used. Examples of such solvents are ethylene glycol and many ester and ether derivatives thereof and various ketones.
  • iron corrosion inhibitors it may be advantageous to add iron corrosion inhibitors to minimize attack on the substrate, thereby also minimizing the amount of smut raised on the surface.
  • iron corrosion inhibitors are organic thio-compounds.
  • the invention disclosed and claimed herein comprises a cast iron product, whose surface contains discrete carboniferous particles and a relatively thin continuous phosphate-containing pre-plate film, essentially covering a surface of said product and a metal plate firmly adherent to said pre-plate film. It has been found that, contrary to expectations, this pre-plate film precludes the depression of the hydrogen overvoltage normally due to the presence of carboniferous particles on the surface of the cast iron which interferes with or entirely prevents the formation of a continuous and satisfactory plate on the article.
  • the thin continuous pre-plate film preferably is produced from a solution of a phosphate ion containing material and a surfactant substance selected from the class con sisting of nonionic and cationic surfactants.
  • the invention also contemplates a process for the application of this pre-plate film to the cast iron surface and the production of an electroplating film directly over and firmly attached to the thin phosphate containing layer.
  • the pre-plate film created on the iron surface is formed from an aqueous solution which comprises from about 2 parts to 36 parts of the phosphate ion and from about 0.15 part to 3.0 parts of the surfactant substance.
  • the film-forming solution may contain miscible solvents, especially in the case of substrates containing unusually large amounts of carbon bearing particles, in an amount of from about 4.0 parts to 20.0 parts based upon the phosphate surfactant content of the solution.
  • the film-forming solution in cases where extensive amounts of deoxidation of the substrate are to be performed by the film-forming solution, it may be advantageous in order to reduce unusually long immersion periods to add iron corrosion inhibitors to minimize attack on the substrate in an amount of from about 0.01 part to 1.0 parts also based upon the phosphate surfactant content of the preparation.
  • the film-forming solution In order to deoxidize effectively the surface of the substrate to be plated, the film-forming solution should be acidic in nature, of a pH ranging from between 0.0 and 3.0 and optimally 0.6 to 0.8. It should also contain 2 to 36 ounces per gallon of the phosphate ion (PO optimally, it should contain 10 to 16 ounces per gallon of this ion.
  • PO optimally, it should contain 10 to 16 ounces per gallon of this ion.
  • the simplest way to provide both the required acidity and the required amount of phosphate ion is to use phosphoric acid in the film-forming solution. In terms of the figures above, this would correspond to the use of 2.5 to 44 ounces per gallon (optimally 12 to 20 ounces per gallon) of 85 percent (wt.) phosphoric acid, as commercially available.
  • the required acidity could be provided by the use of an acid other than phosphoric (such as sulfuric), combined with the use of a soluble phosphate salt.
  • the salts which may be used are the orthophosphates, monohydrogen phosphates and dihydrogen phosphate (PO4 3, HPOK H2PO4 respectively) of sodium, potassium and ammonium ion.
  • a source of the required phosphate ion free acids and the sodium, potassium and ammonium salts thereof of other forms of the phosphate ion such as pyrophosphoric (P 0 metaphosphoric (PO hexametaphosphoric ((PO tetraphosphates (P O and tripolyphosphates (P O
  • P 0 metaphosphoric PO hexametaphosphoric
  • P O and tripolyphosphates P O
  • organic phosphates which, generally speaking, are phosphate esters. The following general reaction shows how phosphoric acid may be readily esterified with organic bases:
  • R may be either CH or C H
  • R may further be H(CHOH) CH where n is 1 or 2.
  • these film-forming solutions must contain surface-active agents, designed to wet preferentially all surfaces being prepared for plating. These may be present in an amount of 0.15 to 3 ounces per gallon; optimally 0.4 to 0.6 ounce per gallon.
  • surface-active agents designed to wet preferentially all surfaces being prepared for plating.
  • these may be present in an amount of 0.15 to 3 ounces per gallon; optimally 0.4 to 0.6 ounce per gallon.
  • we generally prefer cationic or non-ionic surface-active agents the former of the quaternary ammonium type, the latter of the poly (oxyethylenated) alkyl aryl type. More specifically, we generally prefer nonionic agents of the following general formula:
  • R R and R are --H, -OH, CH;;, CH CH CH CH OH,
  • phosphate-ester type surfactants are available as 1, 2 and 3 esters, in the same manner as noted above for the use of lower molecular weight organic phosphate esters:
  • R stands for an organic radical. While we have found that a number of such organic radicals are satisfactory for this purpose, we have obtained good results using agents in which R is a poly (oxyethylenated) alkyl aryl or a poly (oxyethylenated) aliphatic alcohol.
  • H CH -Ar ⁇ OCH CH equals R as above defined and where n is 6 to 20, m is 8 to 10 and Ar is the phenyl or naphthalene group;
  • the solvent which is an optional part of the film-forming solution may be of either or both of two general types.
  • the first type consists of ketones of the general structure CH3COR, WhCI'C R CH3-, C2H5, 01'
  • the total amount of combined solvents present should be 4 to 20 ounces per gallon; optimally, 8 to 12 ounces per gallon. Examples of solvents of the above type are:
  • Acetone CH COCH Methyl ethyl ketone (CH COC H Diacetone alcohol
  • the words Cellosolve and Carbitol are registered trademarks of Union Carbide.
  • the correspondnig esters of each of the above is to be considered. As a typical example, this would be the formula for ethyl Cellosolve phosphate;
  • the film-forming solution may contain organic thio-compounds which act as iron corrosion inhibitors in acid solutions. Such materials may be required if the film-forming solution is used to do an appreciable amount of deoxidizing, leading to extended immersion times of ferriferous substrates in the bath. While not thereby limited, we have found the following compounds to be useful in this regard: NaSCN;
  • C H NCSSNa C H NCSSNa. These inhibitors are generally used at concentrations of less than 1 ounce per gallon.
  • the film-forming solution is generally used at room temperature so as to minimize any attack on the ferriferous substrate, and so as to minimize heating costs. If desired, however, these solutions may be operated at temperatures up to 180 F.
  • the time of immersion at room temperature is generally one to ten minutes, However, it is to be understood that this disclosure is not thereby limited, as particular circumstances could dictate immersion times outside of these ranges.
  • the castings were completely covered even in the lowest current density recesses with a uniformly bright zinc deposit.
  • a process for cyanide zinc electroplating a ferrous metal surface of an object having discrete carboniferous particles in said surface which comprises immersing the object ferrous metal surface having the carboniferous particles in said surface in an aqueous acid solution comprising about 2 to 36 ounces per gallon of phosphate ion, 0.15 to 3 ounces per gallon of at least one lwetting agent selected from the group consisting of nonionic and cationic surfactants, about 4 to ounces per gallon of a miscible solvent selected from the group consisting of compounds of the formulae:
  • R is CH;,, C H or whereinR is H,
  • R is H or H(CH n is l-2 and m is 1-4, and an organic thio compound in a corrosion-inhibiting amount less than 1 ounce per gallon, said aqueous acid solution having a pH of up to 3.0 inclusive and being at a temperature in the range of room temperature to 180 F., for a time sufiicient to form thereon a thin continuous phosphatecontaining film, and electroplating a firmly adherent zinc plate onto the thus coated ferrous metal surface in a cyanide zinc electroplating bath whereby a sufiiciently high hydrogen overvoltage is maintained during the zinc electroplating to enable said electroplating to occur.
  • ferrous metal surface having the discrete carboniferous particles therein is a carburized ferrous metal surface.
  • At least one wetting agent selected from the group consisting of nonionic and cationic surfactants, about 4 to 20 ounces per gallon of a miscible solvent selected from the group consisting of compounds of the formulae:
  • aqueous acid solution having a pH of up to 3.0 inclusive and being at a temperature in the range of room temperature to F., for a time sufiicient to form thereon a thin continuous phosphate-containing film, and electroplating a rlirmly adherent zinc plate onto the thus coated ferrous metal surface in a cyanide zinc electroplating bath whereby a sufficiently high hydrogen overvoltage is maintained during the zinc electroplating to enable said electroplating to occur.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Mechanical Engineering (AREA)
  • Electroplating Methods And Accessories (AREA)
  • Chemical Treatment Of Metals (AREA)
  • Electroplating And Plating Baths Therefor (AREA)
  • Chemically Coating (AREA)
US439987A 1965-03-10 1965-03-15 Process and product for plating on cast,malleable,carburized and carbonitrided irons Expired - Lifetime US3411995A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
US439987A US3411995A (en) 1965-03-15 1965-03-15 Process and product for plating on cast,malleable,carburized and carbonitrided irons
ES0323665A ES323665A1 (es) 1965-03-15 1966-02-28 Un procedimiento de preparacion para galvanostegia de un producto de hierro colado.
GB10063/66A GB1145352A (en) 1965-03-15 1966-03-08 Improvements in process for plating
SE3118/66A SE323562B (cs) 1965-03-15 1966-03-09
DE19661521929 DE1521929C (de) 1965-03-10 1966-03-10 Vorbehandlung eines Gußeisenproduk tes fur die Galvanisierung

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US439987A US3411995A (en) 1965-03-15 1965-03-15 Process and product for plating on cast,malleable,carburized and carbonitrided irons

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2004067796A1 (en) * 2003-01-23 2004-08-12 H.C. Starck Inc. Pre-plating surface treatments for enhanced galvanic-corrosion resistance

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1211218A (en) * 1916-07-31 1917-01-02 Parker Rust Proof Company Of America Process for plating metals.
US2080299A (en) * 1935-04-12 1937-05-11 Du Pont Inhibiting corrosion of metals
FR845119A (fr) * 1938-10-24 1939-08-11 Internat Incorrodible Metal Co Procédé pour le traitement superficiel du fer et de l'acier
US2224695A (en) * 1938-11-25 1940-12-10 Carl F Prutton Inhibitor
US2403426A (en) * 1944-11-14 1946-07-02 American Chem Paint Co Metal coating process
US2456947A (en) * 1944-12-21 1948-12-21 Westinghouse Electric Corp Corrosion resistant coating for metal surfaces
US2502441A (en) * 1946-11-22 1950-04-04 Oakite Prod Inc Phosphate coating of metals
US2552874A (en) * 1950-05-01 1951-05-15 American Chem Paint Co Method of phosphatizing ferriferous surfaces
US2840498A (en) * 1953-06-08 1958-06-24 Parker Rust Proof Co Composition and method for producing combination corrosion resistant and lubricatingcoatings on metals
US3133005A (en) * 1960-12-08 1964-05-12 Hooker Chemical Corp Process for electrodepositing metallic coatings

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1211218A (en) * 1916-07-31 1917-01-02 Parker Rust Proof Company Of America Process for plating metals.
US2080299A (en) * 1935-04-12 1937-05-11 Du Pont Inhibiting corrosion of metals
FR845119A (fr) * 1938-10-24 1939-08-11 Internat Incorrodible Metal Co Procédé pour le traitement superficiel du fer et de l'acier
US2224695A (en) * 1938-11-25 1940-12-10 Carl F Prutton Inhibitor
US2403426A (en) * 1944-11-14 1946-07-02 American Chem Paint Co Metal coating process
US2456947A (en) * 1944-12-21 1948-12-21 Westinghouse Electric Corp Corrosion resistant coating for metal surfaces
US2502441A (en) * 1946-11-22 1950-04-04 Oakite Prod Inc Phosphate coating of metals
US2552874A (en) * 1950-05-01 1951-05-15 American Chem Paint Co Method of phosphatizing ferriferous surfaces
US2840498A (en) * 1953-06-08 1958-06-24 Parker Rust Proof Co Composition and method for producing combination corrosion resistant and lubricatingcoatings on metals
US3133005A (en) * 1960-12-08 1964-05-12 Hooker Chemical Corp Process for electrodepositing metallic coatings

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2004067796A1 (en) * 2003-01-23 2004-08-12 H.C. Starck Inc. Pre-plating surface treatments for enhanced galvanic-corrosion resistance
US7368176B2 (en) 2003-01-23 2008-05-06 H.C. Starck Inc. Pre-plating surface treatments for enhanced galvanic-corrosion resistance
US20080176005A1 (en) * 2003-01-23 2008-07-24 Richard Wu Pre-plating surface treatments for enhanced galvanic-corrosion resistance
US7645494B2 (en) 2003-01-23 2010-01-12 H.C. Starck Inc. Pre-plating surface treatments for enhanced galvanic-corrosion resistance

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SE323562B (cs) 1970-05-04
ES323665A1 (es) 1966-11-16
DE1521929B2 (de) 1972-10-12
GB1145352A (en) 1969-03-12
DE1521929A1 (de) 1970-03-19

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