US3307980A - Treatment of metal surfaces - Google Patents
Treatment of metal surfaces Download PDFInfo
- Publication number
- US3307980A US3307980A US301906A US30190663A US3307980A US 3307980 A US3307980 A US 3307980A US 301906 A US301906 A US 301906A US 30190663 A US30190663 A US 30190663A US 3307980 A US3307980 A US 3307980A
- Authority
- US
- United States
- Prior art keywords
- solution
- aluminum
- per liter
- present
- grams per
- 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
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- 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
- C23C22/34—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 fluorides or complex fluorides
- C23C22/37—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 fluorides or complex fluorides containing also hexavalent chromium compounds
Definitions
- the present invention broadly relates to the art of coating aluminum and alloys thereof, and more particularly is directed to an improved solution composition and method for providing adherent corrosion resistant chromate coatings on aluminum and alloys of aluminum consisting predominantly of aluminum.
- Treating solutions for providing such chromate coatings conventionally comprise an aqueous acidic solution containing hexavalent chromium and either simple or complex fluo-
- the coatings obtained range from a yellow to brown color and can be further modified by incorporating suitable organic dyes in the solution resulting in a coated article having an enhanced decorative appearance.
- the fluoride ion in the solution acts as an activator to accelerate the coating reaction. In spite of the inclusion of this activator agent, however, treatment times are relatively long and the coatings produced are frequently of a relatively low adherent quality.
- a principal object of the present invention to provide an improved chromate treating solution for the treatment of aluminum and alloys of aluminum consisting predominantly of aluminum and which solution composition increases the rate at which a coating is formed on the surfaces of the articles being treated and enhances the adherent characteristics of the coating formed.
- Another object of the present invention is to provide an improved process for forming adherent chromate coatings on aluminum and aluminum alloy surfaces and which process effects a more rapid formation of the coating than processes of similar type heretofore known.
- Still another object of the present invention is to provide an improved chromating solution and process for forming adherent chromate coatings on aluminum and aluminum alloy surfaces and which solution and process are simple to control, of economical preparation and of eflicient and versatile use.
- a controlled quantity of an alpha-amino acid in an aqueous solution containing hexavalent chromium and fluoride ions within the quantities conventionally employed and which solution is applied to the surface of the aluminum or aluminum alloy article by brushing, immersion, flooding, spraying, or the like.
- a controlled quantity of a selenium compound is incorporated in the chromating solution providing an increased rate in coating formation and an intensification in the color of the coating produced.
- the chromating solution in accordance with the pres- 3,307,980 Patented Mar. 7, 1967 ICC ent invention, comprises an aqueous solution incorporating conventional quantities of hexavalent chromium and fluoride ions to which a controlled quantity of either one or a mixture of suitable alpha-amino acids are added.
- the chromating treating solution contains chromium (measured as CrO in an amount broadly ranging from about 1 up to about 10 grams per liter and a fluoride content present in a concentration broadly ranging from about 0.05 to about 5 grams per liter.
- the acidity of the solution is conventionally held within a pH range of between about 1 and about 4.
- the increased activity of the solution and improved adherence of the chromate coatings obtained in accordance with the discovery comprising the present invention is based on the addition of a controlled quantity of an alpha-amino acid to the solution within an amount ranging from about 0.1 to about 10 grams per liter.
- the amino acid additive can comprise a primary, secondary, or tertiary aliphatic alpha-amino acid in which one or both of the hydrogen atoms of the amino group may be substituted in accordance with the general formula as set forth below:
- the amino group is attached to the alpha carbon of the acid molecule.
- the simplest acid corresponding to this formula is glycine wherein R, R and R are hydrogen atoms.
- a secondary alpha-amino acid is typified by sarcosine (N-methyl glycine) wherein either R or R" correspond to the methyl group and R corresponds to a hydrogen atom.
- a more complex alphaamino acid incorporating a tertiary amino group is typi fied by ethylene diamine tetra-acetic acid (EDTA).
- EDTA ethylene diamine tetra-acetic acid
- the alpha-amino acid additive can be introduced into the solution either in the acid form or alternatively as a metal salt of the acid employing a compatible metal which will not interfere with the chromating reaction such as, for example, the alkali metals.
- the hexavalent chromium constituent of the treating solution may conveniently be introduced as chromic acid, chromates or dichromates, as well as mixtures thereof while the fluoride ions in the solution may be derived.
- hydrofluoric acid a simple fluoride such as an alkali metal fluoride salt, a fluosilicate, a fluoborate, for example, as well as mixtures thereof.
- a simple fluoride such as an alkali metal fluoride salt, a fluosilicate, a fluoborate, for example, as well as mixtures thereof.
- the treating solution comprising the present invention effects solution of aluminum from the surfaces of the articles being treated which accumulates in the solution as a complex fluoride ion.
- the accumulation of dissolved aluminum in the treating solution can readily be controlled in accordance with the method described in United States Patent No. 2,967,791, granted January 10, 1961 and assigned to the same assignee as the present invention.
- a portion of the treating solution is passed through a strongly acidic cat ion exchange resin bed and the effluent therefrom is returned to the processing solution.
- the cation exchange resin effects a removal of the dissolved aluminum maintaining the aluminum concentration in the operating solution in a range preferably of from about 0.005% to about 0.4% by Weight.
- the treating solution comprising the present invention is treated in accordance with the process described in the aforementioned patent, it is usually preferred to introduce the alpha-amino acid in the form of an acid instead of a metallic salt since the introduction 3 of such extraneous metal ions to the solution has a tendency to exhaust the cation exchange resin more quickly.
- the aqueous acidic treating solution containing hexavalent chromium, the fluoride ion, and the appropriate quantity of the alpha-amino acid additive may also contain a small quantity of a selenium compound present in an amount ranging from about 0.05 to about 1 gram per liter calculated as SeO
- the selenium compounds which are suitable for this purpose are soluble compounds such as, for example, selenium dioxide, selenious acid, selenic acid, selenates, selenites, as well as mixtures thereof of which selenium dioxide constitutes the preferred material.
- the inclusion of the selenium compound in the solution has been found to provide still further improvements in the rate of coating formation on the aluminum surface and also contributes to an intensification of the color of the coating produced.
- the aqueous acidic'chromating solution either with or without the selenium additive, can readily be applied to the surfaces of aluminum and aluminum alloy workpieces by any of the conventional techniques known in the art including brushing, immersion, flooding, spraying or the like. Due to the high reactivity of the coating solution comprising the present invention, it has been found that it is now possible to obtain satisfactory coatings by spray application of the treating solution at a temperature ranging from about 70 F. to about 130 F. for time periods as low as about 5 seconds. The high reactivity of the solution and the improved coatings produced thereby makes the solution eminently satisfactory for use in spray processes through which continuous strip material is passed.
- Example 1 In order to compare the improved coating characteristics and the improved coatings produced in accordance with the solution and process comprising the present invention, comparisons were made of the coating characteristics of a chromating solution devoid of the alpha-amino acid additive in relation to a treating solution containing a controlled quantity of glycine.
- the conventional chromating solution contained 6 grams per liter CrO and 2 grams per liter H SiF which was applied by spraying to the surface of a commercially pure aluminum panel at a temperature of 120 F. for about '15 seconds. A thin, dusty coating Weighing 20 milligrams per square foot was obtained.
- Example 2 A conventional chromating solution was prepared containing 6 grams per liter potassium dichromate (K Cr O and 10 grams per liter of 40% fluoboric acid (HBF which was sprayed onto an aluminum panel for 1 minute at a temperature of 130 F. A thin, poorly adherent :oating was obtained. The addition of 2 grams per liter of the disodium salt of ethylene diamine tetra-acetic acid :0 the solution produced an adherent golden-yellow coating under the same conditions.
- the solution comprising the present invention can also be simply replenished during use by adding appropriate proportions of the individual constituents to the operating solution or, alternatively, by the addition of an appropriate amount of an aqueous concentrate of the constituents to maintain the concentration of the ingredients within the ranges as hereinbefore set forth.
- a chromating solution for producing an improved chromate coating on the surfaces of aluminum and aluminum alloys consisting predominantly of aluminum comprising an aqueous acidic mixture containing a hexavalent chromium compound present in an amount of from about 1 to about 10 grams per liter calculated as CrO an activator agent comprising fluoride ions present in an amount of from about 0.05 to about 5 grams per liter, and an aqueous soluble aliphatic alpha-amino acid compound selected from the group consisting of primary, secondary, and tertiary alpha-amino acids, compatible metal salts thereof, as well as mixtures thereof present in an amount from about 0.1 to about 10 grams per liter.
- a chromating solution for producing an improved chromate coating on the surfaces of aluminum and alloys consisting predominantly of aluminum comprising an aqueous acidic mixture containing a hexavalent chromium compound present in an amount of from about 1 to about 10 grams per liter calculated as CrO an activator agent comprising fluoride ions present in an amount of from about 0.05 to about 5 grams per liter, an aqueous soluble aliphatic alpha-amino acid compound selected from the group consisting of primary, secondary, tertiary alphaamino acids and compatible metal salts thereof as Well as mixtures thereof present in an amount of from about 0.1 to about 10 grams per liter; and an accelerator agent comprising an aqueous soluble non-precipitate forming selenium compound present in an amount from about 0.05 to about 1 gram per liter calculated as SeO i 3.
- a chromating solution for producing an improved chromate coating on the surfaces of aluminum and aluminum alloys consisting predominantly of aluminum comprising an aqueous acidic mixture having a pH of from about 1 to about 4 and containing a hexavalent chromium compound present in an amount ranging from about 1 to about grams per liter calculated as CrO an activator agent comprising fluoride ions present in an amount from about 0.05 to about 5 grams per liter, and an aqueous soluble aliphatic alpha-amino acid compound selected from the group consisting of glycine, sarcosine, ethylene diamine tetra-acetic acid, the alkali metal salts thereof, as well as mixtures thereof present in an amount of from about 0.1 to about 10 grams per liter.
- a chromating solution for producing an improved chromate coating'on the surfaces of aluminum and aluminum alloys consisting predominantly of aluminum comprising an aqueous acidic mixture having a pH of from about 1 to about 4 and containing a hexavalent chromium compound in an amount of from about 1 to about 10 grams per liter calculated as CrO an activator agent comprising fluoride ions present in an amount of from about 0.05 to about 5 grams per liter, an aqueous soluble aliphatic alpha-amino acid compound selected from the group consisting of glycine, sarcosine, ethylene diamine tetra-acetic acid, the alkali metal salts thereof, as well as mixtures thereof; and an accelerator agent comprising an aqueous solu-ble nonprecipitate forming selenium compound present in an amount from 0.05 to about 1 gram per liter calculated as SeO 5.
- a chromating solution for producing an improved chromate coating on the surfaces of aluminum and aluminum alloys consisting predominantly of aluminum comprising an aqueous acidic mixture having a pH'of from about 1 to about 4 and containing a hexavalent chromium compound selected from the group consisting of chromic acid, chromates, dichromates, and mixtures thereof present in an amount ranging from about 1 to about 10 grams per liter calculated as CrO an activator agent comprising fluoride ions introduced by a water soluble fluorine compound selected from a group consisting of hydrofluoric acid, simple fluorides, fluosilicates, fluoborates, and mixtures thereof present in an amount from about 0.05 to about 5 grams per liter, and an aqueous soluble aliphatic alpha-amino acid compound selected from the group consisting of glycine, sarcosine, ethylene diamine tetra-acetic acid, the alkali metal salts thereof, as well as mixtures thereof present in an amount
- a chromating solution for producing an improved chromate coating on the surfaces of aluminum and aluminum alloys consisting predominantly of aluminum comprising an aqueous acidic mixture having a pH of from about 1 to about 4 and containing a hexavalent chromium compound selected from the group consisting of chromic acid, chromates, dichromates, and mixtures thereof present in an amount ranging from about 1 to about 10 grams per liter calculated as CrO an activator agent comprising fluoride ions introduced by a water soluble fluorine compound selected from a group consisting of hydrofluoric acid, simple fluorides, fluosilicates, fluoborates, and mix tures thereof present in an amount from about 0.05 to about 5 grams per liter, and an aqueous soluble aliphatic alpha-amino acid compound selected from the group consisting of glycine, sarcosine, ethylene diamine tetra-acetic acid, the alkali metal salts thereof, as well as mixtures thereof present in an amount
- the method of producing an improved chromate coating on the surfaces of aluminum and aluminum alloys consisting predominantly of aluminum comprises the steps of applying to the surface an aqueous acidic soluti-on containing a hexavalent chromium compound present in an amount of from about 1 to about 10 grams per liter calculated as CrO an activator agent comprising fluoride ions present in an amount of from about 0.05 to about 5 grams per liter, and an aqueous soluble aliphatic alphaamino acid compound selected from the group consisting of primary, secondary, and tertiary alpha-amino acids, compatible metal salts thereof, as well as mixtures thereof present in an amount of from about 0.1 to about 10 grams per liter, and continuing the application of said solution until a coating results.
- the method of producing an improved chromate coating on the surfaces of aluminum and aluminum alloys consisting predominantly of aluminum comprises the steps of applying to said surfaces an aqueous acidic solution at a temperature ranging from about F. to about F. and containing a hexavalent chromium compound, an activator agent comprising fluoride, an aqueous soluble aliphatic alpha-amino acid compound selected from the group consisting of a primary, secondary, and tertiary alpha-amino acid, compatible metal salts thereof, as well as mixtures thereof present in an amount of from about 0.1 to about 10 grams per liter, and an accelerator agent comprising an aqueous soluble nonprecipitate forming selenium compound present in an amount of from about 0.05 to about 1 gram per liter calculated as 8e0 and continuing the application of said solution until a coating results.
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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)
- Chemical Treatment Of Metals (AREA)
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB31334/62A GB986455A (en) | 1962-08-15 | 1962-08-15 | Improvements relating to the chromating of aluminium surfaces |
Publications (1)
Publication Number | Publication Date |
---|---|
US3307980A true US3307980A (en) | 1967-03-07 |
Family
ID=10321589
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US301906A Expired - Lifetime US3307980A (en) | 1962-08-15 | 1963-08-13 | Treatment of metal surfaces |
Country Status (5)
Country | Link |
---|---|
US (1) | US3307980A (it) |
BE (1) | BE635940A (it) |
CH (1) | CH435913A (it) |
DE (1) | DE1271499B (it) |
GB (1) | GB986455A (it) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3779815A (en) * | 1972-01-03 | 1973-12-18 | Diamond Shamrock Corp | Applying chromic acid-amino acid, or lactam, or amide coating compositions to metals |
US3855010A (en) * | 1972-04-05 | 1974-12-17 | J Matulis | Composition and method for color passivation of zinc and cadmium |
Families Citing this family (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
BE635940A (it) * | 1962-08-15 | |||
GB1130358A (en) * | 1964-11-12 | 1968-10-16 | Toyo Kohan Co Ltd | Process for treating electrolytically chromated metal surfaces |
GB2215740B (en) * | 1988-02-08 | 1992-06-03 | Brent Chemicals Int | Composition and process for treating metal surfaces |
GB8802788D0 (en) * | 1988-02-08 | 1988-03-09 | Brent Chemicals Int | Composition & process for treating metal surfaces |
Citations (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2322205A (en) * | 1939-05-01 | 1943-06-22 | Dow Chemical Co | Method of treating magnesium and its alloys |
GB577731A (en) * | 1944-08-17 | 1946-05-29 | High Duty Alloys Ltd | Improved process for protecting magnesium and magnesium rich alloys against corrosion |
US2438740A (en) * | 1944-03-27 | 1948-03-30 | Canadian Copper Refiners Ltd | Method of protecting the surface of articles formed from a magnesium alloy |
US2507956A (en) * | 1947-11-01 | 1950-05-16 | Lithographic Technical Foundat | Process of coating aluminum |
US2522474A (en) * | 1942-07-02 | 1950-09-12 | Battelle Memorial Institute | Treatment of zinc surfaces |
US2613165A (en) * | 1950-07-03 | 1952-10-07 | Aluminum Co Of America | Surface treatment of magnesium and magnesium alloy articles |
US2786002A (en) * | 1954-04-28 | 1957-03-19 | American Chem Paint Co | Method of treating zinciferous surfaces |
US2904413A (en) * | 1954-06-23 | 1959-09-15 | Jervis Corp | Process of bright dipping zinc base alloys |
GB889322A (en) * | 1960-11-07 | 1962-02-14 | Pyrene Co Ltd | Improvements relating to the chromating of zinc and cadmium |
GB986455A (en) * | 1962-08-15 | 1965-03-17 | Pyrene Co Ltd | Improvements relating to the chromating of aluminium surfaces |
GB990352A (en) * | 1963-08-15 | 1965-04-28 | Pyrene Co Ltd | Improvements relating to the chromating of aluminium |
Family Cites Families (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2844496A (en) * | 1957-02-25 | 1958-07-22 | Newell Isaac Laird | Formation of corrosion resistant films on aluminum |
-
0
- BE BE635940D patent/BE635940A/xx unknown
-
1962
- 1962-08-15 GB GB31334/62A patent/GB986455A/en not_active Expired
-
1963
- 1963-07-30 DE DEP1271A patent/DE1271499B/de active Pending
- 1963-08-07 CH CH977063A patent/CH435913A/de unknown
- 1963-08-13 US US301906A patent/US3307980A/en not_active Expired - Lifetime
Patent Citations (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2322205A (en) * | 1939-05-01 | 1943-06-22 | Dow Chemical Co | Method of treating magnesium and its alloys |
US2522474A (en) * | 1942-07-02 | 1950-09-12 | Battelle Memorial Institute | Treatment of zinc surfaces |
US2438740A (en) * | 1944-03-27 | 1948-03-30 | Canadian Copper Refiners Ltd | Method of protecting the surface of articles formed from a magnesium alloy |
GB577731A (en) * | 1944-08-17 | 1946-05-29 | High Duty Alloys Ltd | Improved process for protecting magnesium and magnesium rich alloys against corrosion |
US2507956A (en) * | 1947-11-01 | 1950-05-16 | Lithographic Technical Foundat | Process of coating aluminum |
US2613165A (en) * | 1950-07-03 | 1952-10-07 | Aluminum Co Of America | Surface treatment of magnesium and magnesium alloy articles |
US2786002A (en) * | 1954-04-28 | 1957-03-19 | American Chem Paint Co | Method of treating zinciferous surfaces |
US2904413A (en) * | 1954-06-23 | 1959-09-15 | Jervis Corp | Process of bright dipping zinc base alloys |
GB889322A (en) * | 1960-11-07 | 1962-02-14 | Pyrene Co Ltd | Improvements relating to the chromating of zinc and cadmium |
GB986455A (en) * | 1962-08-15 | 1965-03-17 | Pyrene Co Ltd | Improvements relating to the chromating of aluminium surfaces |
GB990352A (en) * | 1963-08-15 | 1965-04-28 | Pyrene Co Ltd | Improvements relating to the chromating of aluminium |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3779815A (en) * | 1972-01-03 | 1973-12-18 | Diamond Shamrock Corp | Applying chromic acid-amino acid, or lactam, or amide coating compositions to metals |
US3855010A (en) * | 1972-04-05 | 1974-12-17 | J Matulis | Composition and method for color passivation of zinc and cadmium |
Also Published As
Publication number | Publication date |
---|---|
CH435913A (de) | 1967-05-15 |
DE1271499B (de) | 1968-06-27 |
GB986455A (en) | 1965-03-17 |
BE635940A (it) |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: HOOKER CHEMICALS & PLASTICS CORP 32100 STEPHENSON Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:OXY METAL INDUSTRIES CORPORATION;REEL/FRAME:003942/0016 Effective date: 19810317 |
|
AS | Assignment |
Owner name: OCCIDENTAL CHEMICAL CORPORATION Free format text: CHANGE OF NAME;ASSIGNOR:HOOKER CHEMICAS & PLASTICS CORP.;REEL/FRAME:004126/0054 Effective date: 19820330 |
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AS | Assignment |
Owner name: PARKER CHEMICAL COMPANY, 32100 STEPHENSON HWY., MA Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:OCCIDENTAL CHEMICAL CORPORATION;REEL/FRAME:004194/0047 Effective date: 19830928 |