US3790355A - Coated metal article and method of coating - Google Patents

Coated metal article and method of coating Download PDF

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Publication number
US3790355A
US3790355A US00200224A US3790355DA US3790355A US 3790355 A US3790355 A US 3790355A US 00200224 A US00200224 A US 00200224A US 3790355D A US3790355D A US 3790355DA US 3790355 A US3790355 A US 3790355A
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article
coating
zinc
seconds
chromated
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US00200224A
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S Palisin
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EMPIRE PLATING CO
EMPIRE PLATING CO US
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EMPIRE PLATING CO
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Classifications

    • 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
    • C23C22/24—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 hexavalent chromium compounds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D3/00—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials
    • B05D3/10—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by other chemical means
    • B05D3/102—Pretreatment of metallic substrates
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
    • B05D7/14—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials to metal, e.g. car bodies
    • 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
    • C25D5/48—After-treatment of electroplated surfaces
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D2202/00—Metallic substrate
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D2350/00—Pretreatment of the substrate
    • B05D2350/10—Phosphatation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D2350/00—Pretreatment of the substrate
    • B05D2350/20—Chromatation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D3/00—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials
    • B05D3/02—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by baking
    • B05D3/0254—After-treatment
    • 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.]
    • Y10T428/12535—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.] with additional, spatially distinct nonmetal component
    • Y10T428/12542—More than one such component
    • Y10T428/12549—Adjacent to each other
    • 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.]
    • Y10T428/12535—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.] with additional, spatially distinct nonmetal component
    • Y10T428/12556—Organic component
    • Y10T428/12569—Synthetic resin
    • 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.]
    • Y10T428/12535—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.] with additional, spatially distinct nonmetal component
    • Y10T428/12583—Component contains compound of adjacent metal
    • 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.]
    • Y10T428/12736—Al-base component
    • 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
    • Y10T428/12778—Alternative base metals from diverse categories
    • 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
    • Y10T428/31504—Composite [nonstructural laminate]
    • Y10T428/31942—Of aldehyde or ketone condensation product

Definitions

  • ABSTRACT A metal article having a corrosion-resistant, adherent surface-covering, hydrophobic, thermosetting polymer film.
  • a method -of coating a metal article to make it resistant to corrosion comprising the steps of forming a metallic chromating surface thereof, applying a hydrophobic, thermosetting polymer to a surface thereof and heating the article at a temperature of at least about 300 F. to convert the polymer into a hard, adherent film.
  • the present invention provides extremely corrosionresistant coverings for, and a method of producing such coverings on, metal articles.
  • Such articles maybe composed of iron, steel, aluminum, zinc, bronze or copper alloys.
  • the method consists of chromating a surface of the article or of a layer of metal on; the article and covering the chromated surface with a heat hardened film
  • metal articles when composed of aluminum, cast iron, malleable iron, steel, zinc, bronze or copper alloy are cleaned in any suitable conventional manner, for example, by tumbling the article in caustic soda or by passing an electric current through such a solution with the metal article constituting the anode.
  • the article is rinsed in cold water, is then dipped in a dilute acid solution, and again rinsed in cold water.
  • a percent sulfuric acid solution or a 25 percent hydrochloric solution is sufficient to neutralize the caustic soda.
  • a very weak acid solution is used.
  • the article may be reversely treated in an alkaline cyanide bath, i.e., by passing a current through the bath for about 30 seconds while the article is the anode in the circuit and then reversing the current flow for'about 30 seconds while the article is the cathode in the circuit.
  • the article is rinsed in water if it is to be plated promptly thereafter, or it may be rinsed in a dilute sodium cyanide solution to prevent rusting when it is not to be plated promptly.
  • the thus cleaned metal article composed of iron, bronze or copper alloys is then electrolytically plated in a conventional manner, as by making it the cathode in an electrolytic bath.
  • cadmium or zinc is the coating metal and either may be deposited on the article from a. conventional bath such, for example, as cadmium cyanide or zinc cyanide.
  • Nickel and chro-. mium may also be used as coating metals.
  • Any suitable conventional bath composition may be used for depositing either of these metals, for example, a nickel sulfate bath may serve for the chromium deposition.
  • a current density of about 10 amperes per square foot is suitable and the plating action is continued until between about 0.0002 inch to 0.005 inch layer of the base metal has been deposited on the article.
  • a layer of another metal such, for example, as copper may be applied before the coating of cadmium or zinc is applied/When the article is com- 2 posed of zinc, a coating of cadmium, zinc, nickel or chromium is deposited on the surface thereof. After such deposition, the article is rinsed with water and then is rinsed in dilute aqueous nitric acid.
  • the surface of the coating metal, or of the article if composed of zinc is chromated.
  • This chromating step consists of treating the cadmium or zinc in such a manner as to convert the metal surface thereof into a clear, stain-free finish with corrosion While properties. Whiel various substances may be used for such chromating action, I prefer to use a chromating material consisting of about 90 percent trioxide and about 10 percent sodium bisulfate dissolved inwater, the concentration of this chromating material being between about 6 oz. and about 16 oz. per gallon of water.
  • the article to be chromated is thoroughly rinsed to free it from alkalis and is then dipped into the chromating solution for between about 10 seconds and about 25 seconds.
  • Preferably that solution should be at a temperature between about 65 and about 95 F.
  • the chromated surface on the metal article is then covered with hydrophobic, thermosetting polymer and the article is heated at a temperature between about Hexamethoxy methyl melamine about 15.3% Ethyl Acrylate about l6.0% Methacrylic Acid about l.0% Chromium Trioxide about 0.1% ,Water about 67.6%
  • film-forming compositions which may be used include the hexamethoxy methyl melamine of the foregoing composition with equivalents of the other'ingre-.
  • the above preferred film-forming composition has given new and unexpected results in terms of corrosion prevention.
  • the films formed by this invention had a pencil hardness of l-l-3, excellent flexibility, abrasion resistance and adhesion and evidenced no degradation after being exposed for hours to humidity and to salt spray conditions.
  • films composed of epoxy solvent lacquer had' a pencil hardness of H, good flexibility and abrasion resistance and fair adhesion and were affected when exposed for 100 hours to humidity or to salt spray.
  • Films composed of nitrocellulose had a pencil hardness of H, poor flexibility and abrasion resistance, fair adhesion and were affected when exposed for 25 hours to humidity or salt spray.
  • the method of making a metal article resistant to corrosion which comprises the steps of electroplating, with a metal selected from the group of metals consisting of zinc, cadmium, nickel and chromium, a surface of an article composed of metal selected from the group of metals consisting of aluminum, iron, zinc, brass and copper alloys, chromating the electroplated surface by treating it for between about 15 seconds and about 25 seconds with water containing between about 6 oz. and about 16 oz. per gallon of a liquid composed of about 90 percent of CrO and about 10 percent of sodium bisulphate, rinsing the resulting chromated surface with water, covering the said chromated surface with hydrophobic thermosetting polymer and heating said article to above about 300 F. to convert the polymer into a hard film.
  • a metal article composed of a metal selected from the group of metals consisting of aluminum, iron, brass, copper alloys and zinc, having an electrodeposited coating on a surface thereof selected from the group of metals consisting of zinc, cadmium, nickel and chromium, said coating having a chromated surface formed by being treated for between about seconds and about seconds with water containing between about 6 oz. and about 16 oz. per gallon ofa liquid composed of about 90 percent of CrO and about 10 percent of sodium bisulphate followed by rinsing the chromated surface with water, and a film of hydrophobic thermosetting polymer adhering to said chromated surface, which film has been hardened by heating the article to above about 300 F.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Electrochemistry (AREA)
  • Mechanical Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Wood Science & Technology (AREA)
  • Chemical Treatment Of Metals (AREA)
  • Electroplating Methods And Accessories (AREA)

Abstract

A metal article having a corrosion-resistant, adherent surfacecovering, hydrophobic, thermosetting polymer film. A method of coating a metal article to make it resistant to corrosion comprising the steps of forming a metallic chromating surface thereof, applying a hydrophobic, thermosetting polymer to a surface thereof and heating the article at a temperature of at least about 300* F. to convert the polymer into a hard, adherent film.

Description

United States Patent 1191 Palisin, Jr.
COATED METAL ARTICLE AND METHOD OF COATING Stephen P. Palisin, Jr., Cleveland,
Ohio
Assignee: The Empire Plating Company,
Cleveland, Ohio Filed: Nov. 18, 1971 Appl. No.: 200,224
Related US. Application Data Continuation of Ser. No. 887,397, Dec. 22, l969, abandoned.
Inventor:
[1.8. CI.'. 29/195, 204/38 E, l48/6.2l Int. Cl B23p 3/00, C23c 7/26 Field of Search .1 204/38 S, 38 E, 38 R, 37;
References Cited UNITED STATES PATENTS 9/1970 Smith et al. 204/38 S Modern Electroplating by Lowenheim, 1963 page 425 Primary Examiner-John H. Mack Assistant Examiner-R. L. Andrews Attorney, Agent, or FirmBlythe D. Watts et al.
[ ABSTRACT A metal article having a corrosion-resistant, adherent surface-covering, hydrophobic, thermosetting polymer film.
A method -of coating a metal article to make it resistant to corrosion comprising the steps of forming a metallic chromating surface thereof, applying a hydrophobic, thermosetting polymer to a surface thereof and heating the article at a temperature of at least about 300 F. to convert the polymer into a hard, adherent film.
3 Claims, No Drawings of a hydrophobic, thermosetting polymer.
COATED METAL ARTICLE AND METHOD OF COATING This application is a continuation of my pending application Ser. No. 887,397, filed Dec. 22, 1969 and now abandoned.
BACKGROUND The prior art most nearly pertinent to this invention and known to me is U. S. Pat. Nos. 3,031,333 and 3,556,869. These patents disclose processes which were not devised to, and would not, produce articles which would meet the severe service conditions met by articles produced by the present invention.
SUMMARY The present invention provides extremely corrosionresistant coverings for, and a method of producing such coverings on, metal articles. Such articles maybe composed of iron, steel, aluminum, zinc, bronze or copper alloys. The method consists of chromating a surface of the article or of a layer of metal on; the article and covering the chromated surface with a heat hardened film According to the present invention, metal articles when composed of aluminum, cast iron, malleable iron, steel, zinc, bronze or copper alloy are cleaned in any suitable conventional manner, for example, by tumbling the article in caustic soda or by passing an electric current through such a solution with the metal article constituting the anode. After such cleaning, the article is rinsed in cold water, is then dipped in a dilute acid solution, and again rinsed in cold water. When the article is composed of ferrous metal, aluminum,bronze or copper alloys, a percent sulfuric acid solution or a 25 percent hydrochloric solution is sufficient to neutralize the caustic soda. When the article is composed of zinc, a very weak acid solution is used.
In certain instances where even better cleaning of a ferrous metal article is desired or where its surface is to be activated, the article may be reversely treated in an alkaline cyanide bath, i.e., by passing a current through the bath for about 30 seconds while the article is the anode in the circuit and then reversing the current flow for'about 30 seconds while the article is the cathode in the circuit. Following this reverse treatment, the article is rinsed in water if it is to be plated promptly thereafter, or it may be rinsed in a dilute sodium cyanide solution to prevent rusting when it is not to be plated promptly.
The thus cleaned metal article composed of iron, bronze or copper alloys is then electrolytically plated in a conventional manner, as by making it the cathode in an electrolytic bath. Preferably cadmium or zinc is the coating metal and either may be deposited on the article from a. conventional bath such, for example, as cadmium cyanide or zinc cyanide. Nickel and chro-. mium may also be used as coating metals. Any suitable conventional bath composition may be used for depositing either of these metals, for example, a nickel sulfate bath may serve for the chromium deposition. A current density of about 10 amperes per square foot is suitable and the plating action is continued until between about 0.0002 inch to 0.005 inch layer of the base metal has been deposited on the article.
On aluminum, a layer of another metal such, for example, as copper may be applied before the coating of cadmium or zinc is applied/When the article is com- 2 posed of zinc, a coating of cadmium, zinc, nickel or chromium is deposited on the surface thereof. After such deposition, the article is rinsed with water and then is rinsed in dilute aqueous nitric acid.
Following the electroplating and rinsing operations, the surface of the coating metal, or of the article if composed of zinc, is chromated. This chromating step consists of treating the cadmium or zinc in such a manner as to convert the metal surface thereof into a clear, stain-free finish with corrosion While properties. Whiel various substances may be used for such chromating action, I prefer to use a chromating material consisting of about 90 percent trioxide and about 10 percent sodium bisulfate dissolved inwater, the concentration of this chromating material being between about 6 oz. and about 16 oz. per gallon of water. The article to be chromated is thoroughly rinsed to free it from alkalis and is then dipped into the chromating solution for between about 10 seconds and about 25 seconds. Preferably that solution should be at a temperature between about 65 and about 95 F. Upon removing the article from the chromating bath, it is thoroughly rinsed with water.
The chromated surface on the metal article is then covered with hydrophobic, thermosetting polymer and the article is heated at a temperature between about Hexamethoxy methyl melamine about 15.3% Ethyl Acrylate about l6.0% Methacrylic Acid about l.0% Chromium Trioxide about 0.1% ,Water about 67.6%
Other film-forming compositions which may be used include the hexamethoxy methyl melamine of the foregoing composition with equivalents of the other'ingre-.
dients thereof.
The above preferred film-forming composition has given new and unexpected results in terms of corrosion prevention. For example, the films formed by this invention had a pencil hardness of l-l-3, excellent flexibility, abrasion resistance and adhesion and evidenced no degradation after being exposed for hours to humidity and to salt spray conditions. In contrast therewith, films composed of epoxy solvent lacquer had' a pencil hardness of H, good flexibility and abrasion resistance and fair adhesion and were affected when exposed for 100 hours to humidity or to salt spray.
Films composed of nitrocellulose had a pencil hardness of H, poor flexibility and abrasion resistance, fair adhesion and were affected when exposed for 25 hours to humidity or salt spray.
Having thus described this invention in such full, clear, concise and exact terms as to enable any person skilled in the art to which it pertains to make and use the same, and having set forth the best mode contemplated of carrying out this invention, I state that the subject matter which I regard as being my invention is particularly pointed out and distinctly claimed in what is claimed, it being understood that equivalents or modifications of, or substitutions for, parts of the above specifically described embodiments of the invention may be made without departing from the scope of the invention as set forth in what is claimed.
What is claimed is:
l. The method of making a metal article resistant to corrosion which comprises the steps of electroplating, with a metal selected from the group of metals consisting of zinc, cadmium, nickel and chromium, a surface of an article composed of metal selected from the group of metals consisting of aluminum, iron, zinc, brass and copper alloys, chromating the electroplated surface by treating it for between about 15 seconds and about 25 seconds with water containing between about 6 oz. and about 16 oz. per gallon of a liquid composed of about 90 percent of CrO and about 10 percent of sodium bisulphate, rinsing the resulting chromated surface with water, covering the said chromated surface with hydrophobic thermosetting polymer and heating said article to above about 300 F. to convert the polymer into a hard film.
2. A metal article composed of a metal selected from the group of metals consisting of aluminum, iron, brass, copper alloys and zinc, having an electrodeposited coating on a surface thereof selected from the group of metals consisting of zinc, cadmium, nickel and chromium, said coating having a chromated surface formed by being treated for between about seconds and about seconds with water containing between about 6 oz. and about 16 oz. per gallon ofa liquid composed of about 90 percent of CrO and about 10 percent of sodium bisulphate followed by rinsing the chromated surface with water, and a film of hydrophobic thermosetting polymer adhering to said chromated surface, which film has been hardened by heating the article to above about 300 F.
3. A method of protecting a metallic surface to render it highly resistant to salt spray corrosion and to abrasion, wherein the surface is composed of a metal selected from the group of metals consisting of aluminum, iron, zinc, brass and copper alloys, comprising the steps of:
a. electroplating the surface with a metal selected from the group of metals consisting of zinc, cadmium, nickel and chromium;
b. chromating the electroplated surface to produce a clear, blemish free colorless chromate coating thereon by treating it for between about 15 seconds and about 25 seconds with water containing between about 6 oz. and about 16 oz. per gallon of a liquid composed of about,90 percent of CrO and about 10 percent sodium bisulphate;
c. rinsing the chromated surface with water to flush away chromating solution remaining thereon;
d. coating the chromated surface with a transparent colorless hydrophobic thermosetting polymer; and
e. heating the article to above about 300 F to convert the polymer to a hard, colorless transparent film thereby providing the surface with a blemish free corrosion resistant finish.
UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORREFJTION PATENT NO. 3,790,355 P DATED 3 February 5, 1974 E M Stephen P. Palisin, Jr.
It is certified thai error appears in the ab0ve-identified patent and that said Letters Patent are hereby corrected as shown below:
Column 2, line 10, after "corrosion" insert r eslstlng Signed and Sealed this i sixteenth Day of September 1975 [SEAL] Arrest:
RUTH c. MASON c. MARSHALL DANN Arresting Officer Commissioner uflarenls and Trademarks a I fio v UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 ,790,I 55 Dated February 5 1974 lfiventofls) StephenP. Palisin, Jr.
It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:
Column 1, line 60 after "the? insert H nickel deposition and a chromic acid bath may serve for the Column 2 line 10,
WhieD should read While same line 10 cancel "While" Column 2, line 13, after the first occurrence'of the word "percent" insert 4? chromium H Signed and sealed this 17th day of September 1974.
(SEAL) Attest:
C. MARSHALL DANN GIBSON JR. i in Officer Commissioner of Patents FORM PC4050 USCOMM-DC 60376-P69 US. GOVERNMENT PRINTING OFFICE 7 I965 0'35633L

Claims (2)

  1. 2. A metal article composed of a metal selected from the group of metals consisting of aluminum, iron, brass, copper alloys and zinc, having an electrodeposited coating on a surface thereof selected from the group of metals consisting of zinc, cadmium, nickel and chromium, said coating having a chromated surface formed by being treated for between about 15 seconds and about 25 seconds with water containing between about 6 oz. and about 16 oz. per gallon of a liquid composed of about 90 percent of CrO3 and about 10 percent of sodium bisulphate followed by rinsing the chromated surface with water, and a film of hydrophobic thermosetting polymer adhering to said chromated surface, which film has been hardened by heating the article to above about 300* F.
  2. 3. A method of protecting a metallic surface to render it highly resistant to salt spray corrosion and to abrasion, wherein the surface is composed of a metal selected from the group of metals consisting of aluminum, iron, zinc, brass and copper alloys, comprising the steps of: a. electroplating the surface with a metal selected from the group of metals consisting of zinc, cadmium, nickel and chromium; b. chromating the electroplated surface to produce a clear, blemish free colorless chromate coating thereon by treating it for between about 15 seconds and about 25 seconds with water containing between about 6 oz. and about 16 oz. per gallon of a liquid composed of about 90 percent of CrO3 and about 10 percent sodium bisulphate; c. rinsing the chromated surface with water to flush away chromating solution remaining thereon; d. coating the chromated surface with a transparent colorless hydrophobic thermosetting polymer; and e. heating the article to above about 300* F to convert the polymer to a hard, colorless transparent film thereby providing the surface with a blemish free corrosion resistant finish.
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Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3958317A (en) * 1974-09-25 1976-05-25 Rockwell International Corporation Copper surface treatment for epoxy bonding
US3961993A (en) * 1971-11-18 1976-06-08 The Empire Plating Company Coated metal article and method of coating
US4285783A (en) * 1979-07-06 1981-08-25 Metropolitan Wire Corporation Coating for metal shelving and method of applying same
US4401519A (en) * 1981-02-25 1983-08-30 Olin Corporation Method for producing reticulate electrode for electrolytic cells
US5718466A (en) * 1995-11-13 1998-02-17 The Eastern Company Racking resistant door control mechanism and method of fabrication
US5718467A (en) * 1995-11-13 1998-02-17 The Eastern Company Racking resistant door control mechanism
WO2001043888A2 (en) * 1999-12-17 2001-06-21 Chemetall Gmbh Method for producing coated metal surfaces and the use of said metal surfaces
US20040155026A1 (en) * 2003-02-10 2004-08-12 Mandal Robert P. Integrally formed bake plate unit for use in wafer fabrication system
US20050129932A1 (en) * 2003-12-16 2005-06-16 Briley Robert E. Rivet and coating technique

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US2746915A (en) * 1951-10-15 1956-05-22 Autoyre Co Inc Electrolytic metal treatment and article
US3526486A (en) * 1967-02-21 1970-09-01 Nat Steel Corp Corrosion resistant ferrous metal articles and method of preparing the same

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US2746915A (en) * 1951-10-15 1956-05-22 Autoyre Co Inc Electrolytic metal treatment and article
US3526486A (en) * 1967-02-21 1970-09-01 Nat Steel Corp Corrosion resistant ferrous metal articles and method of preparing the same

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
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Modern Electroplating by Lowenheim, 1963 page 425 *

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3961993A (en) * 1971-11-18 1976-06-08 The Empire Plating Company Coated metal article and method of coating
US3958317A (en) * 1974-09-25 1976-05-25 Rockwell International Corporation Copper surface treatment for epoxy bonding
US4285783A (en) * 1979-07-06 1981-08-25 Metropolitan Wire Corporation Coating for metal shelving and method of applying same
US4401519A (en) * 1981-02-25 1983-08-30 Olin Corporation Method for producing reticulate electrode for electrolytic cells
US5718466A (en) * 1995-11-13 1998-02-17 The Eastern Company Racking resistant door control mechanism and method of fabrication
US5718467A (en) * 1995-11-13 1998-02-17 The Eastern Company Racking resistant door control mechanism
WO2001043888A2 (en) * 1999-12-17 2001-06-21 Chemetall Gmbh Method for producing coated metal surfaces and the use of said metal surfaces
WO2001043888A3 (en) * 1999-12-17 2001-12-06 Chemetall Gmbh Method for producing coated metal surfaces and the use of said metal surfaces
US20030051772A1 (en) * 1999-12-17 2003-03-20 Heribert Domes Method for producing coated metal surfaces and the use of said metal surfaces
US20040155026A1 (en) * 2003-02-10 2004-08-12 Mandal Robert P. Integrally formed bake plate unit for use in wafer fabrication system
US6891134B2 (en) * 2003-02-10 2005-05-10 Asml Netherlands B.V. Integrally formed bake plate unit for use in wafer fabrication system
US20050129932A1 (en) * 2003-12-16 2005-06-16 Briley Robert E. Rivet and coating technique

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