US3563811A - Coated ferruginous metal and method - Google Patents
Coated ferruginous metal and method Download PDFInfo
- Publication number
- US3563811A US3563811A US734242A US3563811DA US3563811A US 3563811 A US3563811 A US 3563811A US 734242 A US734242 A US 734242A US 3563811D A US3563811D A US 3563811DA US 3563811 A US3563811 A US 3563811A
- Authority
- US
- United States
- Prior art keywords
- coating
- acidic
- ferruginous
- substrate
- acid
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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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
- C23C22/26—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 containing also organic compounds
- C23C22/27—Acids
-
- 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
- Y10T428/27—Web or sheet containing structurally defined element or component, the element or component having a specified weight per unit area [e.g., gms/sq cm, lbs/sq ft, etc.]
- Y10T428/273—Web or sheet containing structurally defined element or component, the element or component having a specified weight per unit area [e.g., gms/sq cm, lbs/sq ft, etc.] of coating
Definitions
- the acidic coating solution contains a hexavalent-chromium-providing substance, an organic polybasic acid or a salt thereof, and an inorganic acid or salt thereof. Elevated temperature curing of such solutions applied to ferruginous substrates provides a surface coating of excellent corrosion resistance.
- the present invention is directed to a coated ferruginous metal substrate surface comprising a coating on the surface of such substrate of between about 3200 milligrams per square foot of the residue obtained upon heating an applied acidic, corrosion-resistant, hexavalent-chromium-containing coating solution at a temperature substantially above 325 F. but below about 550 F. for a period of time sufficient to vaporize volatile substituents from the applied coating solution and deposit such residue at least substantially bonded to such ferruginous surface, wherein the coating solution is such a solution as disclosed in U.S. Pat. 2,559,812.
- this invention relates to a method for protecting ferruginous metal substrate surfaces with an adherent, corrosion resistant, hexavalent-chromiurn-containing coating solution.
- compositions shown in the above-mentioned U.S. patent which compositions are also referred to herein for convenience as acidic coating compositions, are used herein to coat ferruginous metal surfaces, e.g., iron, stainless steel, or steel such as cold-rolled steel.
- the materials in such coating compositions include 4-18 weight percent of a hexavalent-chromium-providing substance, e.g., chromic acid, supplying at least about 4 weight percent chromic acid, and also include about 0.5-9 Weight percent of an organic polybasic acid, e.g., citric or tartaric, as well as 0.1-8 Weight percent of an inorganic acid; some salts of such acids may also be employed.
- the inorganic acids used are the readily commercially available acids, and as such, are employed within the range from about 0.18%.
- hydrochloric acid there is preferably employed in the composition between about 0.18% of an aqueous solution containing, at atmospheric pressure, about 30 to 36 percent of hydrogen chloride.
- the temperature of the acidic coating composition during application to the ferruginous substrate can be room temperature, it also may be at a moderate temperature of up to -180 F.
- Such compositions can be coated on the ferruginous surface typically by immersing the metal in a bath, or spraying the acidic coating composition on the surface, or by brushing or flowing such solution onto the surface.
- the substrate After application of the acidic coating composition, the substrate is heated at a temperature substantially above about 325 F. but below about 550 F. for a period of time sufficient to vaporize volatile substituents from the applied coating solution and deposit a residue at least substantially bonded to the surface. After such heating, the substrate surface is dry to the touch and the residue sufiiciently bonded to the surface to withstand typically at least about two inch-pounds of impact without removal of coating to bare metal on the convex, i.e., reverse surface. For such impact testing a metal ram of specified weight, in pounds, with a hemispherical contact surface is allowed to drop on the coated panel from a predetermined height, in inches.
- the panel prior to such testing the panel is typically topcoated as has been more specifically described hereinbelow.
- air drying e.g., within the temperature range from about 65 to about 200 F. and for a time of a few minutes or less, will precede heating.
- Heating at a temperature which is not substantially above about 325 F. can provide resulting coated substrates which exhibit corrosion resistance comparable or even downgraded from the corrosion resistance obtained without any heating of the applied acidic coating composition. Moreover, heating at temperatures above about 550 F. can result in some final film degradation.
- the substrate is heated at a temperature between about 375 525 F.
- the substrate is heated for at least about 5 seconds, but, for economy, the heating is not continued for substantially more than about 10 minutes. Heating for less than about 5 seconds can be insufiicient to prepare tough, adherent coatings even for extremely elevated temperature heating.
- the heating is accomplished by baking in a convection oven or by curing under infrared lamps.
- the acidic coating compositions are applied to the substrate in an amount yielding, after curing, between about 3-200 milligrams of residue per square foot of substrate metal surface.
- the presence of less than about 3 milligrams per square foot of such residue may be insufficient to offer desirable enhancement in corrosion resistance and the presence of more than about 200 milligrams of coating residue per square foot can be uneconomical.
- the acidic coating composition is applied in an amount to provide a coating residue of between about 30-100 milligrams per square foot.
- the coating composition may contain a non-ionic wetting agent such as alkylphenoxypolyoxyethylene ethanol, e.g., commercial nonylphenoxypolyoxyethylene ethanol, in concentrations typically up to about 3 grams per liter of the solution.
- a non-ionic wetting agent such as alkylphenoxypolyoxyethylene ethanol, e.g., commercial nonylphenoxypolyoxyethylene ethanol, in concentrations typically up to about 3 grams per liter of the solution.
- the substrate Before applying the coating composition to the substrate, it is desirable that the substrate be thoroughly cleaned.
- a commercial alkaline cleaning composition which combines washing and mild abrasive treatments can be employed for this purpose, e.g., an aqueous trisodium phosphate-sodium hydroxide cleaning solution.
- the substrate can undergo cleaning plus etching, e.g., with hydrofluoric acid etching agent.
- etching e.g., with hydrofluoric acid etching agent.
- a mixture can be applied which incorporates an etching agent in with such solution.
- an additional suitable surface for applying the coating composition is one wherein the metal substrate has been treated to exhibit a loose, powdery residue which is retained on the substrate for subsequent application of the acidic coating composition. Such residues can promote adhesion for later applied paints.
- any suitable paint i.e., a paint, primer, including electrocoating primers, enamel, varnish, or lacquer.
- paints can contain pigment in a hinder or can be unpigmented, e.g., generally cellulose lacquers, rosin varnishes, and oleoresinous varnishes, as for example tung oil varnish.
- the paints can be solvent reduced or they can be water reduced, e.g., latex or water-soluble resins, including modified or soluble alkyds, or the paints can have reactive solvents such as in the polyesters or polyurethanes.
- paints which can be used include oil paints, including phenolic resin paints, solvent-reduced alkyds, epoxys, acrylics, vinyl, including polyvinyl butyral and oil-wax-type coatings such as linseed oil-parafiin wax paints.
- oil paints including phenolic resin paints, solvent-reduced alkyds, epoxys, acrylics, vinyl, including polyvinyl butyral and oil-wax-type coatings such as linseed oil-parafiin wax paints.
- the paints can be applied as mill finishes.
- PREPARATION OF TEST PANELS Steel test panels (typically 4" x 12", and being cold rolled, low carbon steel panels, or plain, mild steel panels, or hot-dipped galvanized steel panels) are prepared for coating application by immersing in water which has incorporated therein typically about 30 grams of cleaning solution per liter of water.
- the cleaning solution is prepared from phosphoric acid, potassium hydroxide, and a 4 wetting agent and the cleaning bath is maintained at a temperature of 160-180 F. Additionally, before cleaning, the mild steel and galvanized steel panels are vapor degreased with perchlorethylene and subsequently heated to 350 F. for 10 minutes.
- the coating composition is applied by dipping the test panel into such composition, removing and draining excess composition from the panel, air drying at room temperature until the coating is dry to the touch prior to any curing. Panels which are then selected for curing are typically placed in a convection oven for a time up to about 6 minutes thereby achieving substrate temperatures as shown in the example.
- CORROSION RESISTANCE TEST ASTM Bl1764.
- Corrosion resistance of coated panels is measured by means of the standard salt spray (fog) test for paints and varnishes, ASTM B-l1764. In this test, panels are placed in a chamber kept at constant temperature where they are exposed to a fine spray (fog) of a 5% salt solution for specified periods of time, rinsed in water and dried. The extent of corrosion and film removal on the test panels can then be measured in inches of coating failure away from scribe lines as explained in greater detail hereinafter in the example.
- the paint film (topcoat) referred to in the example is a commercial white alkyd enamel topcoat typically applied by dip-coating panels into the enamel.
- This paint is prepared from a modified alkyd resin based upon a system of partially polymerized phthalic acid and glycerine.
- the paint contains weight percent solids and has a viscosity of 50 seconds as measured on a No. 4 Ford cup at 70 F.
- the coating is cured by baking in a convection oven for 20 minutes at a temperature of 320325 F.
- EXAMPLE Panels are prepared in the manner described hereinabove and coating compositions are applied to these panels by the method disclosed hereinbefore. As shown in the table below, the compositions employed include two acidic coating compositions as well as a comparative chromic acid/succinic acid/succinimide/phosphoric acid composition. All applied coating compositions are cured at temperatures reported in the table below. Additionally, the table shows the results of the corrosion resistance test (salt spray) and each reported figure is an average from at least two tested panels.
- the metal substrates employed are shown in the table, and all panels have been topcoated with the alkyd enamel topcoat, and the applied topcoat cured, as abovedescribed.
- the figures presented in the table for the corrosion resistance test e.g., indicate the average inches of coating failure away from scribe lines which have been cut through to the base metal, in an X configuration on the panel surface, prior to subjecting the panels to the test.
- the first composition reported in the table has been taught heretofore for use as a corrosion-inhibiting coating for Zinc substrates, wherein such use is unaccompanied by elevated temperature curing. This teaching is supported by the results shown above, that is, the curing at elevated temperature of such composition on zinc (the galvanized steel substrate), provides very poor corrosion protection for the zinc.
- the elevated temperature curing i.e., the 425 435 F. curing
- the acidic coating compositions applied over ferruginous substrates provides coated surfaces achieving excellent, enhanced corrosion protection.
- an enhancement in coating integrity of more than five times greater is achieved by elevated temperature curing rather than simply room temperature curing.
- the enhancement in coating integrity for elevated temperature curing is even more pronounced.
- the comparative coating composition i.e., the last composition reported in the table
- the coating composition has the same ingredients with the exception that only 10 grams per liter (g./l.) of succinimide are employed in such compositions.
- Comparative panels, some cured at room temperature, and some cured at the elevated temperature of 425-435 F., but all topcoated with the standard alkyd topcoat, are all subjected for 168 hours to the corrosion resistance test d scribed hereinbefore.
- the panels cured at the elevated temperature show an average coating failure away from scribe lines of of an inch. However, the panels which are merely air dried show an average coating failure under the same conditions of only 6 of an inch.
- the method of protecting a ferruginous metal substrate surface with an adherent residue from an acidic, corrosion resistant, hexavalent-chromium-containing coating solution wherein the protected metal surface exhibits enhanced corrosion resistance comprises:
- said coating solution comprises:
- salts in said groups (a), (b), and (c) are present in said solution in anionic equivalent amounts of the amount of acid specified.
- a coated ferruginous metal substrate comprising a coating on the surface of said substrate of between about 3-200 milligrams per square foot of the residue obtained upon heating an applied corrosion resistant, acidic, hexavalent-chromium-containing coating solution at a substrate temperature substantially above about 325 F. but below about 550 F. for a period of time sufficient to vaporize volatile substituents from the applied coating so lution and deposit said residue at least substantially bonded to said surface, wherein said acidic coating solution comprises:
- salts in said groups (a), (b), and (c) are present in said solution in anionic equivalent amounts of the amount of acid specified.
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- Chemical & Material Sciences (AREA)
- General Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Application Of Or Painting With Fluid Materials (AREA)
- Chemical Treatment Of Metals (AREA)
Abstract
Description
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US73424268A | 1968-06-04 | 1968-06-04 |
Publications (1)
Publication Number | Publication Date |
---|---|
US3563811A true US3563811A (en) | 1971-02-16 |
Family
ID=24950867
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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US734242A Expired - Lifetime US3563811A (en) | 1968-06-04 | 1968-06-04 | Coated ferruginous metal and method |
Country Status (1)
Country | Link |
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US (1) | US3563811A (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3964914A (en) * | 1974-08-16 | 1976-06-22 | The United States Of America As Represented By The United States Energy Research And Development Administration | Electromarking solution |
US5001173A (en) * | 1987-05-11 | 1991-03-19 | Morton Coatings, Inc. | Aqueous epoxy resin compositions and metal substrates coated therewith |
US5082698A (en) * | 1987-05-11 | 1992-01-21 | Morton Coatings, Inc. | Aqueous epoxy resin compositions and metal substrates coated therewith |
-
1968
- 1968-06-04 US US734242A patent/US3563811A/en not_active Expired - Lifetime
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3964914A (en) * | 1974-08-16 | 1976-06-22 | The United States Of America As Represented By The United States Energy Research And Development Administration | Electromarking solution |
US5001173A (en) * | 1987-05-11 | 1991-03-19 | Morton Coatings, Inc. | Aqueous epoxy resin compositions and metal substrates coated therewith |
US5082698A (en) * | 1987-05-11 | 1992-01-21 | Morton Coatings, Inc. | Aqueous epoxy resin compositions and metal substrates coated therewith |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: DIAMOND SHAMROCK CHEMICALS COMPANY Free format text: CHANGE OF NAME;ASSIGNOR:DIAMOND SHAMROCK CORPORATION CHANGED TO DIAMOND CHEMICALS COMPANY;REEL/FRAME:004197/0130 |
|
AS | Assignment |
Owner name: METAL COATINGS INTERNATIONAL INC. A DE CORP. Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:DIAMOND SHAMROCK CHEMICALS COMPANY;REEL/FRAME:004326/0164 Effective date: 19840831 |
|
AS | Assignment |
Owner name: NATIONAL CITY BANK AS AGENT FOR BANKS Free format text: SECURITY INTEREST;ASSIGNOR:METAL COATINGS INTERNATONAL INC. A DE CORP;REEL/FRAME:004352/0906 Effective date: 19840831 |
|
AS | Assignment |
Owner name: METAL COATINGS INTERNATIONAL INC., STATELESS Free format text: ASSIGNMENT OF ASSIGNORS INTEREST. SEE RECORD FOR DETAILS;ASSIGNOR:NATIONAL CITY BANK, AS AGENT;REEL/FRAME:004969/0537 Effective date: 19880916 Owner name: METAL COATINGS INTERNATIONAL INC., A CORP. OF DE Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:NATIONAL CITY BANK, AS AGENT;REEL/FRAME:004969/0537 Effective date: 19880916 |