US20050121115A1 - Hexavalent chromium-free sealing method applicable after sulfuric anodization of aluminum alloys, a sealing solution used in said method, and an article treated using said method - Google Patents
Hexavalent chromium-free sealing method applicable after sulfuric anodization of aluminum alloys, a sealing solution used in said method, and an article treated using said method Download PDFInfo
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- US20050121115A1 US20050121115A1 US11/000,058 US5804A US2005121115A1 US 20050121115 A1 US20050121115 A1 US 20050121115A1 US 5804 A US5804 A US 5804A US 2005121115 A1 US2005121115 A1 US 2005121115A1
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- lithium
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- 238000007789 sealing Methods 0.000 title claims abstract description 74
- 238000000034 method Methods 0.000 title claims abstract description 31
- 229910000838 Al alloy Inorganic materials 0.000 title claims abstract description 12
- 238000002048 anodisation reaction Methods 0.000 title description 11
- 150000003839 salts Chemical class 0.000 claims abstract description 34
- 239000010941 cobalt Substances 0.000 claims abstract description 31
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 claims abstract description 31
- 229910017052 cobalt Inorganic materials 0.000 claims abstract description 28
- 239000000758 substrate Substances 0.000 claims abstract description 23
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims abstract description 21
- 229910052744 lithium Inorganic materials 0.000 claims abstract description 21
- 229910052751 metal Inorganic materials 0.000 claims abstract description 13
- 239000002184 metal Substances 0.000 claims abstract description 13
- 238000005260 corrosion Methods 0.000 claims abstract description 12
- 230000007797 corrosion Effects 0.000 claims abstract description 11
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 10
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 10
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims abstract description 9
- 239000011780 sodium chloride Substances 0.000 claims abstract description 9
- 229910000428 cobalt oxide Inorganic materials 0.000 claims abstract description 5
- FUJCRWPEOMXPAD-UHFFFAOYSA-N lithium oxide Chemical compound [Li+].[Li+].[O-2] FUJCRWPEOMXPAD-UHFFFAOYSA-N 0.000 claims abstract description 5
- 229910001947 lithium oxide Inorganic materials 0.000 claims abstract description 5
- 238000004519 manufacturing process Methods 0.000 claims abstract description 3
- DBMJMQXJHONAFJ-UHFFFAOYSA-M Sodium laurylsulphate Chemical compound [Na+].CCCCCCCCCCCCOS([O-])(=O)=O DBMJMQXJHONAFJ-UHFFFAOYSA-M 0.000 claims description 10
- 239000002253 acid Substances 0.000 claims description 10
- KGBXLFKZBHKPEV-UHFFFAOYSA-N boric acid Chemical compound OB(O)O KGBXLFKZBHKPEV-UHFFFAOYSA-N 0.000 claims description 10
- 235000019333 sodium laurylsulphate Nutrition 0.000 claims description 10
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 claims description 9
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 claims description 9
- 239000004327 boric acid Substances 0.000 claims description 8
- XGZVUEUWXADBQD-UHFFFAOYSA-L lithium carbonate Chemical compound [Li+].[Li+].[O-]C([O-])=O XGZVUEUWXADBQD-UHFFFAOYSA-L 0.000 claims description 8
- 229910052808 lithium carbonate Inorganic materials 0.000 claims description 8
- 229940011182 cobalt acetate Drugs 0.000 claims description 7
- QAHREYKOYSIQPH-UHFFFAOYSA-L cobalt(II) acetate Chemical compound [Co+2].CC([O-])=O.CC([O-])=O QAHREYKOYSIQPH-UHFFFAOYSA-L 0.000 claims description 7
- 239000004094 surface-active agent Substances 0.000 claims description 7
- IIPYXGDZVMZOAP-UHFFFAOYSA-N lithium nitrate Chemical compound [Li+].[O-][N+]([O-])=O IIPYXGDZVMZOAP-UHFFFAOYSA-N 0.000 claims description 6
- FEWJPZIEWOKRBE-JCYAYHJZSA-N Dextrotartaric acid Chemical compound OC(=O)[C@H](O)[C@@H](O)C(O)=O FEWJPZIEWOKRBE-JCYAYHJZSA-N 0.000 claims description 3
- FEWJPZIEWOKRBE-UHFFFAOYSA-N Tartaric acid Natural products [H+].[H+].[O-]C(=O)C(O)C(O)C([O-])=O FEWJPZIEWOKRBE-UHFFFAOYSA-N 0.000 claims description 3
- 229910021446 cobalt carbonate Inorganic materials 0.000 claims description 3
- UFMZWBIQTDUYBN-UHFFFAOYSA-N cobalt dinitrate Chemical compound [Co+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O UFMZWBIQTDUYBN-UHFFFAOYSA-N 0.000 claims description 3
- 229910001981 cobalt nitrate Inorganic materials 0.000 claims description 3
- 229940044175 cobalt sulfate Drugs 0.000 claims description 3
- 229910000361 cobalt sulfate Inorganic materials 0.000 claims description 3
- KTVIXTQDYHMGHF-UHFFFAOYSA-L cobalt(2+) sulfate Chemical compound [Co+2].[O-]S([O-])(=O)=O KTVIXTQDYHMGHF-UHFFFAOYSA-L 0.000 claims description 3
- ZOTKGJBKKKVBJZ-UHFFFAOYSA-L cobalt(2+);carbonate Chemical compound [Co+2].[O-]C([O-])=O ZOTKGJBKKKVBJZ-UHFFFAOYSA-L 0.000 claims description 3
- XIXADJRWDQXREU-UHFFFAOYSA-M lithium acetate Chemical compound [Li+].CC([O-])=O XIXADJRWDQXREU-UHFFFAOYSA-M 0.000 claims description 3
- INHCSSUBVCNVSK-UHFFFAOYSA-L lithium sulfate Inorganic materials [Li+].[Li+].[O-]S([O-])(=O)=O INHCSSUBVCNVSK-UHFFFAOYSA-L 0.000 claims description 3
- 239000011975 tartaric acid Substances 0.000 claims description 3
- 235000002906 tartaric acid Nutrition 0.000 claims description 3
- RBTVSNLYYIMMKS-UHFFFAOYSA-N tert-butyl 3-aminoazetidine-1-carboxylate;hydrochloride Chemical compound Cl.CC(C)(C)OC(=O)N1CC(N)C1 RBTVSNLYYIMMKS-UHFFFAOYSA-N 0.000 claims description 3
- IVMYJDGYRUAWML-UHFFFAOYSA-N cobalt(ii) oxide Chemical compound [Co]=O IVMYJDGYRUAWML-UHFFFAOYSA-N 0.000 claims description 2
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 claims description 2
- 239000000243 solution Substances 0.000 description 32
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 19
- 239000011148 porous material Substances 0.000 description 7
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 6
- 229910052804 chromium Inorganic materials 0.000 description 6
- 239000011651 chromium Substances 0.000 description 6
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 4
- 229910052799 carbon Inorganic materials 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- 239000003595 mist Substances 0.000 description 3
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 229910003002 lithium salt Inorganic materials 0.000 description 2
- 159000000002 lithium salts Chemical class 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 238000009877 rendering Methods 0.000 description 2
- 230000001988 toxicity Effects 0.000 description 2
- 231100000419 toxicity Toxicity 0.000 description 2
- UDHXJZHVNHGCEC-UHFFFAOYSA-N Chlorophacinone Chemical compound C1=CC(Cl)=CC=C1C(C=1C=CC=CC=1)C(=O)C1C(=O)C2=CC=CC=C2C1=O UDHXJZHVNHGCEC-UHFFFAOYSA-N 0.000 description 1
- 239000003929 acidic solution Substances 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- KRVSOGSZCMJSLX-UHFFFAOYSA-L chromic acid Substances O[Cr](O)(=O)=O KRVSOGSZCMJSLX-UHFFFAOYSA-L 0.000 description 1
- JOPOVCBBYLSVDA-UHFFFAOYSA-N chromium(6+) Chemical compound [Cr+6] JOPOVCBBYLSVDA-UHFFFAOYSA-N 0.000 description 1
- 150000001868 cobalt Chemical class 0.000 description 1
- CKFRRHLHAJZIIN-UHFFFAOYSA-N cobalt lithium Chemical compound [Li].[Co] CKFRRHLHAJZIIN-UHFFFAOYSA-N 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 229910052593 corundum Inorganic materials 0.000 description 1
- 230000000593 degrading effect Effects 0.000 description 1
- SOCTUWSJJQCPFX-UHFFFAOYSA-N dichromate(2-) Chemical compound [O-][Cr](=O)(=O)O[Cr]([O-])(=O)=O SOCTUWSJJQCPFX-UHFFFAOYSA-N 0.000 description 1
- ZOMNIUBKTOKEHS-UHFFFAOYSA-L dimercury dichloride Chemical class Cl[Hg][Hg]Cl ZOMNIUBKTOKEHS-UHFFFAOYSA-L 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- AWJWCTOOIBYHON-UHFFFAOYSA-N furo[3,4-b]pyrazine-5,7-dione Chemical compound C1=CN=C2C(=O)OC(=O)C2=N1 AWJWCTOOIBYHON-UHFFFAOYSA-N 0.000 description 1
- 229910001385 heavy metal Inorganic materials 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- -1 hydrogen ions Chemical class 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 239000003973 paint Substances 0.000 description 1
- 230000035699 permeability Effects 0.000 description 1
- 229910001845 yogo sapphire Inorganic materials 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
- C25D11/02—Anodisation
- C25D11/04—Anodisation of aluminium or alloys based thereon
- C25D11/18—After-treatment, e.g. pore-sealing
- C25D11/24—Chemical after-treatment
- C25D11/246—Chemical after-treatment for sealing layers
Definitions
- the invention relates to a sealing method for producing a layer or film of oxide which is resistant to saline corrosion on a metal substrate, to the sealing solution used in said method, and to an article treated by said method.
- the present invention relates to the application of said sealing method-or said sealing solution to a metal substrate formed from an aluminum or aluminum alloy substrate, said method being carried out after a prior sulfuric anodization step.
- Aluminum enjoys natural protection against atmospheric corrosion by oxidation of its surface, resulting in the formation of amorphous Al 2 O 3 type alumina. That alumina forms naturally in air and can also result from sulfuric acid anodization, which is preferable when a layer is to be produced rapidly and, moreover, when it has to be thicker. This is the case in conventional anodization of the sulfuric anodization (SA) type (sulfuric anodic oxydation), which produces a thickness of 10 micrometers ( ⁇ m) to 20 ⁇ m and up to 100 ⁇ m in the case of “hard” anodization.
- SA sulfuric anodization
- a thin layer of alumina on the surface of aluminum alloys is not sufficiently resistant to the corrosion to which the part is subjected.
- the alumina which is formed has a columnar structure with a geometry which is close to a hexagonal symmetry, with pores rendering it relatively sensitive to its environment, in particular permeable to chemical attack.
- the sealing which is to be carried out is aimed at fixing (metallic) elements in said pores to reduce their permeability in order to enhance the anti-corrosive properties of the alumina layer without, however, degrading the mechanical properties of the alumina.
- the alumina layer is sealed in known manner by placing the part in a chemical bath.
- that bath is a solution based on chromic acid, which allows the pores to be plugged with hexavalent chromium or chromium VI.
- Sealing methods of that type used to plug the pores of the alumina layer present on the surface of an aluminum or aluminum alloy part to form a film which is resistant to saline corrosion, have conventionally used acidic solutions comprising chromium VI, as described in U.S. Pat. Nos. 2,796,370 and 2,796,371.
- the present invention aims to overcome the problems with prior art sealing solutions, in particular problems with chromium toxicity, by proposing a novel sealing method using a sealing solution that contains no chromium, that produces good results and that is easy to carry out, in particular in an industrial context.
- the sealing method of the present invention comprises steps consisting in:
- said “mixed cobalt/lithium chemical sealing” can protect a previously anodized substrate, forming an extremely adhesive sealing layer which has anti-corrosion properties and good paint keying properties.
- a combination of at least one simple cobalt II salt and at least one simple lithium III salt provides very good results which are relatively superior to those obtained by using only at least one simple cobalt II salt or by using only at least one simple lithium III salt.
- said simple cobalt II salt is from the group constituted by cobalt sulfate, cobalt nitrate, cobalt carbonate and cobalt acetate.
- said simple cobalt II salt is cobalt acetate Co(CH 3 COO) 2 ,4H 2 O in a concentration in the range 3 grams/liter (g/liter) to 6 g/liter, i.e. in the range 1.2 ⁇ 10 ⁇ 2 mole/liter to 2.41 ⁇ 10 ⁇ 2 mole/liter, preferably in the range 4 g/liter to 5 g/liter, i.e. in the range 1.61 ⁇ 10 ⁇ 2 mole/liter to 2.01 ⁇ 10 ⁇ 2 mole/liter.
- said simple lithium III salt is from the group constituted by lithium sulfate, lithium nitrate, lithium carbonate and lithium acetate.
- said simple lithium III salt is lithium carbonate LiCO 3 in a concentration in the range 0.5 g/liter to 1.5 g/liter, i.e. in the range 6.77 ⁇ 10 ⁇ 3 mole/liter to 2.03 ⁇ 10 ⁇ 2 mole/liter, preferably in the range 0.75 g/liter to 1 g/liter, i.e. in the range 1.02 ⁇ 10 ⁇ 2 mole/liter to 1.35 ⁇ 10 ⁇ 2 mole/liter.
- said sealing solution also comprises at least one weak acid from the group constituted by boric acid, acetic acid, citric acid and tartaric acid.
- said weak acid is boric acid H 3 BO 3 in a concentration in the range 3 g/liter to 6 g/liter, i.e. in the range 4.85 ⁇ 10 ⁇ 2 mole/liter to 9.7 ⁇ 10 ⁇ 2 mole/liter, preferably in the range 4 g/liter to 5 g/liter, i.e. in the range 6.47 ⁇ 10 ⁇ 2 mole/liter to 8.09 ⁇ 10 ⁇ 2 mole/liter.
- Said solution has the additional advantage of being easy to reproduce, of giving a homogeneous result, and of allowing the sealing solution to be re-used because of the buffer effect of the weak acid which stabilizes the pH of the sealing solution.
- Said weak acid can buffer the sealing solution which then has a pH in the range 5 to 6, advantageously in the range 5.1 to 5.9, preferably 5.5 ⁇ 0.1.
- the sealing solution in question also comprises a surfactant such as sodium lauryl sulfate and/or sodium dodecyl sulfate C 12 H 25 NaO 4 S.
- a surfactant such as sodium lauryl sulfate and/or sodium dodecyl sulfate C 12 H 25 NaO 4 S.
- said surfactant is sodium lauryl sulfate present in a concentration in the range 1.5 mg/liter to 3.5 mg/liter, i.e. in the range 5.20 ⁇ 10 ⁇ 6 mole/liter to 1.21 ⁇ 10 ⁇ 5 mole/liter, preferably in the range 2 mg/liter to 3 mg/liter, i.e. in the range 6.94 ⁇ 10 ⁇ 6 mole/liter to 1.04 ⁇ 10 ⁇ 5 mole/liter.
- Adding such a compound can enhance the results (a more even layer and better distribution of simple cobalt and lithium salts in the pores of the alumina). In fact, it contributes to reducing the surface tension between the metal substrate and the sealing solution, and it also improves the pH stability of the solution by capturing hydrogen ions H + liberated by the weak acid.
- the temperature of the sealing solution is over 87° C., preferably over 90° C., advantageously over 95° C., and more preferably in the range 95° C. to 98° C.
- the duration of the step for bringing the substrate into contact with the sealing solution is more than 15 minutes (min.), advantageously more than 20 min., and preferably in the range 20 min. to 25 min.
- the present invention also pertains to a sealing solution comprising at least one simple cobalt II salt, at least one simple lithium III salt and being buffered, by means of which a mixed cobalt/lithium film is obtained.
- the present invention also pertains to a treated article resulting from carrying out the method of the type defined above, using the sealing solution of the type defined above.
- said article comprises a sealed anodization film having a thickness in the range 15 ⁇ m to 20 ⁇ m.
- the proposal of the present invention renders it possible to produce, in a simple and certain manner and without recourse to chromium, mixed cobalt/lithium sealing resulting in a film having corrosion resistance properties on a metal substrate.
- FIG. 1 shows a section through a specimen (AUZGN blade) treated using the method of the present invention, after 790 hours exposure to a saline mist;
- FIG. 2 shows a top view of the surface appearance of a specimen treated using the method of the present invention.
- a sealing solution was obtained the pH of which was kept at 5.5 ⁇ 0.1 as the solution was buffered by the boric acid.
- FIG. 1 is a photograph showing a section of the specimen after exposure to a saline mist for 790 hours:
- said article comprises:
- the article treated using the method of the invention has a film formed by a layer of sealed alumina, which is non porous and has a conventional cracked structure at its surface. This can be seen in the accompanying photograph shown in FIG. 2 .
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- General Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Chemical Treatment Of Metals (AREA)
- Sealing Battery Cases Or Jackets (AREA)
- Other Surface Treatments For Metallic Materials (AREA)
Abstract
Description
- The invention relates to a sealing method for producing a layer or film of oxide which is resistant to saline corrosion on a metal substrate, to the sealing solution used in said method, and to an article treated by said method.
- In particular, the present invention relates to the application of said sealing method-or said sealing solution to a metal substrate formed from an aluminum or aluminum alloy substrate, said method being carried out after a prior sulfuric anodization step.
- Aluminum enjoys natural protection against atmospheric corrosion by oxidation of its surface, resulting in the formation of amorphous Al2O3 type alumina. That alumina forms naturally in air and can also result from sulfuric acid anodization, which is preferable when a layer is to be produced rapidly and, moreover, when it has to be thicker. This is the case in conventional anodization of the sulfuric anodization (SA) type (sulfuric anodic oxydation), which produces a thickness of 10 micrometers (μm) to 20 μm and up to 100 μm in the case of “hard” anodization.
- However, a thin layer of alumina on the surface of aluminum alloys is not sufficiently resistant to the corrosion to which the part is subjected.
- In contrast, with anodization, the alumina which is formed has a columnar structure with a geometry which is close to a hexagonal symmetry, with pores rendering it relatively sensitive to its environment, in particular permeable to chemical attack.
- For this reason, such pores have to be plugged by sealing. The sealing which is to be carried out is aimed at fixing (metallic) elements in said pores to reduce their permeability in order to enhance the anti-corrosive properties of the alumina layer without, however, degrading the mechanical properties of the alumina.
- In particular, after sulfuric anodization, the alumina layer is sealed in known manner by placing the part in a chemical bath. In accordance with a current sealing method, that bath is a solution based on chromic acid, which allows the pores to be plugged with hexavalent chromium or chromium VI.
- Sealing methods of that type, used to plug the pores of the alumina layer present on the surface of an aluminum or aluminum alloy part to form a film which is resistant to saline corrosion, have conventionally used acidic solutions comprising chromium VI, as described in U.S. Pat. Nos. 2,796,370 and 2,796,371.
- However, it should be noted that using solutions based on chromium VI is now prohibited because of the toxicity of that heavy metal and new legal constraints based on environmental considerations.
- Alternatively, other sealing solutions have been proposed in U.S. Pat. Nos. 5,411,606 and 5,472,524 and in European patent EP-A-0 488 430, which use sealing solutions comprising complex salts based on cobalt III.
- However, that type of sealing solution is relatively expensive and difficult to use because the pH and the complex salts based on cobalt III are unstable—they have a tendency to precipitate out, depending on the age of the bath. For that reason, that type of solution is unstable, rendering operations not strictly reproducible, deleteriously affecting the quality of the layers obtained.
- The present invention aims to overcome the problems with prior art sealing solutions, in particular problems with chromium toxicity, by proposing a novel sealing method using a sealing solution that contains no chromium, that produces good results and that is easy to carry out, in particular in an industrial context.
- To this end, the sealing method of the present invention comprises steps consisting in:
-
- providing a buffered sealing solution, preferably based on an aqueous reaction solution, comprising at least one simple cobalt II salt and at least one simple lithium III salt; and
- bringing said metal substrate having a previously anodized surface into contact with said sealing solution for a period that is sufficient to form a mixed cobalt/lithium oxide film obtained by chemical conversion.
- Thus, said “mixed cobalt/lithium chemical sealing” can protect a previously anodized substrate, forming an extremely adhesive sealing layer which has anti-corrosion properties and good paint keying properties.
- In the case of an aluminum substrate or an aluminum alloy substrate, this means that the film is formed when the pores of the alumina are plugged by metallic cobalt and lithium salts.
- In this manner, it is understood that the presence of a simple cobalt II salt and a simple lithium II salt, which are products in routine use, renders said method extremely easy to carry out.
- Surprisingly, a combination of at least one simple cobalt II salt and at least one simple lithium III salt provides very good results which are relatively superior to those obtained by using only at least one simple cobalt II salt or by using only at least one simple lithium III salt.
- Preferably, said simple cobalt II salt is from the group constituted by cobalt sulfate, cobalt nitrate, cobalt carbonate and cobalt acetate. In particular, said simple cobalt II salt is cobalt acetate Co(CH3COO)2,4H2O in a concentration in the range 3 grams/liter (g/liter) to 6 g/liter, i.e. in the range 1.2×10−2 mole/liter to 2.41×10−2 mole/liter, preferably in the range 4 g/liter to 5 g/liter, i.e. in the range 1.61×10−2 mole/liter to 2.01×10−2 mole/liter.
- Preferably, said simple lithium III salt is from the group constituted by lithium sulfate, lithium nitrate, lithium carbonate and lithium acetate. In particular, said simple lithium III salt is lithium carbonate LiCO3 in a concentration in the range 0.5 g/liter to 1.5 g/liter, i.e. in the range 6.77×10−3 mole/liter to 2.03×10−2 mole/liter, preferably in the range 0.75 g/liter to 1 g/liter, i.e. in the range 1.02×10−2 mole/liter to 1.35×10−2 mole/liter.
- In a preferred implementation, said sealing solution also comprises at least one weak acid from the group constituted by boric acid, acetic acid, citric acid and tartaric acid. In particular, said weak acid is boric acid H3BO3 in a concentration in the range 3 g/liter to 6 g/liter, i.e. in the range 4.85×10−2 mole/liter to 9.7×10−2 mole/liter, preferably in the range 4 g/liter to 5 g/liter, i.e. in the range 6.47×10−2 mole/liter to 8.09×10−2 mole/liter.
- Said solution has the additional advantage of being easy to reproduce, of giving a homogeneous result, and of allowing the sealing solution to be re-used because of the buffer effect of the weak acid which stabilizes the pH of the sealing solution.
- Said weak acid can buffer the sealing solution which then has a pH in the range 5 to 6, advantageously in the range 5.1 to 5.9, preferably 5.5±0.1.
- In a preferred but optional implementation, the sealing solution in question also comprises a surfactant such as sodium lauryl sulfate and/or sodium dodecyl sulfate C12H25NaO4S.
- In particular, said surfactant is sodium lauryl sulfate present in a concentration in the range 1.5 mg/liter to 3.5 mg/liter, i.e. in the range 5.20×10−6 mole/liter to 1.21×10−5 mole/liter, preferably in the range 2 mg/liter to 3 mg/liter, i.e. in the range 6.94×10−6 mole/liter to 1.04×10−5 mole/liter.
- Adding such a compound can enhance the results (a more even layer and better distribution of simple cobalt and lithium salts in the pores of the alumina). In fact, it contributes to reducing the surface tension between the metal substrate and the sealing solution, and it also improves the pH stability of the solution by capturing hydrogen ions H+ liberated by the weak acid.
- In a further preferred implementation, the temperature of the sealing solution is over 87° C., preferably over 90° C., advantageously over 95° C., and more preferably in the range 95° C. to 98° C.
- Preferably, the duration of the step for bringing the substrate into contact with the sealing solution is more than 15 minutes (min.), advantageously more than 20 min., and preferably in the range 20 min. to 25 min.
- The present invention also pertains to a sealing solution comprising at least one simple cobalt II salt, at least one simple lithium III salt and being buffered, by means of which a mixed cobalt/lithium film is obtained.
- The present invention also pertains to a treated article resulting from carrying out the method of the type defined above, using the sealing solution of the type defined above.
- In a preferred implementation, said article comprises a sealed anodization film having a thickness in the range 15 μm to 20 μm.
- In general, the proposal of the present invention renders it possible to produce, in a simple and certain manner and without recourse to chromium, mixed cobalt/lithium sealing resulting in a film having corrosion resistance properties on a metal substrate.
- Other advantages and characteristics of the invention will become apparent from the following description made with reference to the accompanying drawings in which:
-
FIG. 1 shows a section through a specimen (AUZGN blade) treated using the method of the present invention, after 790 hours exposure to a saline mist; -
FIG. 2 shows a top view of the surface appearance of a specimen treated using the method of the present invention. - Highly conclusive tests were carried out using aluminum specimens which had undergone sulfuric anodization for 40 minutes (thickness of alumina layer obtained: 16 micronmeters (um) and which had been immersed in a sealing solution for more than 20 minutes at a temperature of 97° C.±2° C.
- The sealing solution used was an aqueous solution which had the following characteristics:
-
- simple cobalt II salt: cobalt acetate Co(CH3COO)2,4H2O in a concentration in the range 3 g/liter to 6 g/liter, i.e. in the range 1.2×10−2 mole/liter to 2.41×10−2 mole/liter, preferably in the range 4 g/liter to 5 g/liter, i.e. in the range 1.61×10−2 mole/liter to 2.01×10−2 mole/liter;
- simple lithium II salt: lithium carbonate LiCO3 in a concentration in the range 0.5 g/liter to 1.5 g/liter, i.e. in the range 6.77×10−3 mole/liter to 2.03×10−2 mole/liter, preferably in the range 0.75 g/liter to 1 g/liter, i.e. in the range 1.02×10−2 mole/liter to 1.35×10−2 mole/liter;
- weak acid: boric acid in a concentration in the range 3 g/liter to 6 g/liter, i.e. in the range 4.85×10−2 mole/liter to 9.7×10−2 mole/liter, preferably in the range 4 g/liter to 5 g/liter, i.e. in the range 6.47×10−2 mole/liter to 8.09×10−2 mole/liter;
- as the surfactant: sodium lauryl sulfate present in a concentration in the range 1.5 mg/liter to 3.5 mg/liter, i.e. in the range 5.20×10−6 mole/liter to 1.21×10−5 mole/liter, preferably in the range 2 mg/liter to 3 mg/liter, i.e. in the range 6.94×10−6 mole/liter to 1.04×10−5 mole/liter; and
- temperature: 90° C.±3° C.
- A sealing solution was obtained the pH of which was kept at 5.5±0.1 as the solution was buffered by the boric acid.
- These anodized and sealed specimens in a cobalt-lithium medium had an anodic potential of −650 millivolts (mV) (measured with respect to a saturated calomel electrode, SCE). This high plate (anodic) protection value was thus of the same order of magnitude as that obtained for a prior art dichromate solution (−655 mV SCE).
- Further, said aluminum alloy (2024) specimens withstood more than 700 hours of the saline mist resistance test in accordance with French standard AFNOR NFX 41002 or International standard ISO 9227.
-
FIG. 1 is a photograph showing a section of the specimen after exposure to a saline mist for 790 hours: -
- the
substrate 10 produced from aluminum alloy 2024 is surmounted by the alumina layer 12 sealed by sulfuric anodization in which three different zones with different compositions can be distinguished: - the lower layer of sealed
alumina 12 a surmounting thesubstrate 10 and which is characterized by a composition having an absence of cobalt and carbon; - the upper layer of sealed
alumina 12 b surmounting the lower layer of sealedalumina 12 a and which is characterized by a composition having a very low concentration of cobalt and carbon; and - the surface of the sealed
alumina layer 12 c surmounting the lower layer of sealedalumina 12 a and which is characterized by a composition comprising cobalt and carbon relating to the presence of cobalt salts in the sealing solution and carbon from the lithium carbonate.
- the
- It will be understood that thanks to this sealing method and to the sealing solution of the invention, an article is obtained which has good corrosion resistance properties, in particular as regards saline corrosion.
- In a preferred implementation, said article comprises:
-
- a metal substrate based on aluminum or an aluminum alloy;
- a sealed film comprising aluminum oxide, cobalt oxide and lithium oxide.
- It can also be noted that the article treated using the method of the invention has a film formed by a layer of sealed alumina, which is non porous and has a conventional cracked structure at its surface. This can be seen in the accompanying photograph shown in
FIG. 2 .
Claims (28)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FR0314382A FR2863276B1 (en) | 2003-12-09 | 2003-12-09 | CHROMIUM-FREE HEXAVALENT-FREE CLAMPING METHOD AFTER SULFURIC ANODIZATION OF ALUMINUM ALLOYS, COLLAGE SOLUTION USED THEREIN, AND TREATED ARTICLE THEREFROM |
FR0314382 | 2003-12-09 |
Publications (1)
Publication Number | Publication Date |
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US20050121115A1 true US20050121115A1 (en) | 2005-06-09 |
Family
ID=34508618
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Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US11/000,058 Abandoned US20050121115A1 (en) | 2003-12-09 | 2004-12-01 | Hexavalent chromium-free sealing method applicable after sulfuric anodization of aluminum alloys, a sealing solution used in said method, and an article treated using said method |
Country Status (5)
Country | Link |
---|---|
US (1) | US20050121115A1 (en) |
EP (1) | EP1541718A3 (en) |
JP (1) | JP4334466B2 (en) |
CA (1) | CA2487990A1 (en) |
FR (1) | FR2863276B1 (en) |
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN102392284A (en) * | 2011-11-03 | 2012-03-28 | 湖南大学 | One-step treatment method for coloring and sealing aluminium anodic oxide film |
CN103290453A (en) * | 2013-05-10 | 2013-09-11 | 黄山金瑞泰科技有限公司 | Hole sealing agent for hole sealing processing of computer-to-plate (CTP) printing plate material |
CN103469276A (en) * | 2013-09-16 | 2013-12-25 | 杭州和韵科技有限公司 | Method for improving acid-base corrosion resistance property of aluminum anode oxide film |
CN103710736A (en) * | 2013-12-23 | 2014-04-09 | 广西博士海意信息科技有限公司 | Aluminum alloy hole sealing agent |
EP2957658A4 (en) * | 2014-02-18 | 2016-07-27 | Suzuki Motor Corp | Metal member with excellent corrosion resistance, manufacturing method thereof, and metal member repair material and repair method |
CN112135931A (en) * | 2018-05-24 | 2020-12-25 | 斯瑞昂高级电池公司 | Plating lithiated transition metal oxides using low purity starting precursors |
US20220380904A1 (en) * | 2013-05-14 | 2022-12-01 | Prc-Desoto International, Inc. | Permanganate based conversion coating compositions |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
KR101270671B1 (en) * | 2011-03-25 | 2013-06-03 | 주식회사 영광와이케이엠씨 | Composition for sealing treatment of aluminium anodizing |
CA3032156A1 (en) | 2016-08-12 | 2018-02-15 | Ppg Industries Ohio, Inc. | Pretreatment composition |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5411607A (en) * | 1993-11-10 | 1995-05-02 | Novamax Technologies Holdings, Inc. | Process and composition for sealing anodized aluminum surfaces |
US6447665B1 (en) * | 1997-08-22 | 2002-09-10 | Henkel Corporation | Faster two-step sealing of anodized aluminum surfaces |
-
2003
- 2003-12-09 FR FR0314382A patent/FR2863276B1/en not_active Expired - Lifetime
-
2004
- 2004-12-01 US US11/000,058 patent/US20050121115A1/en not_active Abandoned
- 2004-12-02 CA CA002487990A patent/CA2487990A1/en not_active Abandoned
- 2004-12-07 EP EP04292901A patent/EP1541718A3/en not_active Withdrawn
- 2004-12-08 JP JP2004354934A patent/JP4334466B2/en active Active
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5411607A (en) * | 1993-11-10 | 1995-05-02 | Novamax Technologies Holdings, Inc. | Process and composition for sealing anodized aluminum surfaces |
US6447665B1 (en) * | 1997-08-22 | 2002-09-10 | Henkel Corporation | Faster two-step sealing of anodized aluminum surfaces |
Cited By (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN102392284A (en) * | 2011-11-03 | 2012-03-28 | 湖南大学 | One-step treatment method for coloring and sealing aluminium anodic oxide film |
CN103290453A (en) * | 2013-05-10 | 2013-09-11 | 黄山金瑞泰科技有限公司 | Hole sealing agent for hole sealing processing of computer-to-plate (CTP) printing plate material |
US20220380904A1 (en) * | 2013-05-14 | 2022-12-01 | Prc-Desoto International, Inc. | Permanganate based conversion coating compositions |
CN103469276A (en) * | 2013-09-16 | 2013-12-25 | 杭州和韵科技有限公司 | Method for improving acid-base corrosion resistance property of aluminum anode oxide film |
CN103710736A (en) * | 2013-12-23 | 2014-04-09 | 广西博士海意信息科技有限公司 | Aluminum alloy hole sealing agent |
EP2957658A4 (en) * | 2014-02-18 | 2016-07-27 | Suzuki Motor Corp | Metal member with excellent corrosion resistance, manufacturing method thereof, and metal member repair material and repair method |
US9944801B2 (en) | 2014-02-18 | 2018-04-17 | Suzuki Motor Corporation | Metal member having excellent corrosion resistance, method for producing the same, and material and method for repairing metal member |
CN112135931A (en) * | 2018-05-24 | 2020-12-25 | 斯瑞昂高级电池公司 | Plating lithiated transition metal oxides using low purity starting precursors |
Also Published As
Publication number | Publication date |
---|---|
JP2005171385A (en) | 2005-06-30 |
JP4334466B2 (en) | 2009-09-30 |
FR2863276B1 (en) | 2006-01-20 |
CA2487990A1 (en) | 2005-06-09 |
FR2863276A1 (en) | 2005-06-10 |
EP1541718A3 (en) | 2008-10-15 |
EP1541718A2 (en) | 2005-06-15 |
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