WO2024074774A1 - Method for post-anodisation sealing of aluminium and aluminium alloys without using chromium - Google Patents
Method for post-anodisation sealing of aluminium and aluminium alloys without using chromium Download PDFInfo
- Publication number
- WO2024074774A1 WO2024074774A1 PCT/FR2023/051483 FR2023051483W WO2024074774A1 WO 2024074774 A1 WO2024074774 A1 WO 2024074774A1 FR 2023051483 W FR2023051483 W FR 2023051483W WO 2024074774 A1 WO2024074774 A1 WO 2024074774A1
- Authority
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- WIPO (PCT)
- Prior art keywords
- aluminum
- hexafluorozirconate
- tungstate
- post
- silicate
- Prior art date
Links
- 238000000034 method Methods 0.000 title claims abstract description 80
- 229910000838 Al alloy Inorganic materials 0.000 title claims abstract description 74
- 238000007789 sealing Methods 0.000 title claims abstract description 50
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 title claims abstract description 46
- 229910052782 aluminium Inorganic materials 0.000 title claims abstract description 45
- 238000002048 anodisation reaction Methods 0.000 title claims abstract description 34
- 239000011651 chromium Substances 0.000 title abstract description 15
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 title abstract description 12
- 229910052804 chromium Inorganic materials 0.000 title abstract description 9
- 239000004411 aluminium Substances 0.000 title abstract 4
- 239000003973 paint Substances 0.000 claims abstract description 15
- 238000007743 anodising Methods 0.000 claims description 31
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 31
- 238000005470 impregnation Methods 0.000 claims description 20
- 229910001868 water Inorganic materials 0.000 claims description 18
- 238000011282 treatment Methods 0.000 claims description 17
- 229910045601 alloy Inorganic materials 0.000 claims description 13
- 239000000956 alloy Substances 0.000 claims description 13
- 239000008367 deionised water Substances 0.000 claims description 13
- 229910021641 deionized water Inorganic materials 0.000 claims description 13
- 150000003839 salts Chemical class 0.000 claims description 12
- PBYZMCDFOULPGH-UHFFFAOYSA-N tungstate Chemical compound [O-][W]([O-])(=O)=O PBYZMCDFOULPGH-UHFFFAOYSA-N 0.000 claims description 12
- 150000001340 alkali metals Chemical class 0.000 claims description 10
- 229910052910 alkali metal silicate Inorganic materials 0.000 claims description 9
- 229910052915 alkaline earth metal silicate Inorganic materials 0.000 claims description 9
- 238000005238 degreasing Methods 0.000 claims description 9
- 238000002360 preparation method Methods 0.000 claims description 9
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 claims description 8
- 239000007864 aqueous solution Substances 0.000 claims description 8
- 150000002696 manganese Chemical class 0.000 claims description 8
- 239000000243 solution Substances 0.000 claims description 8
- 238000004381 surface treatment Methods 0.000 claims description 8
- AAQNGTNRWPXMPB-UHFFFAOYSA-N dipotassium;dioxido(dioxo)tungsten Chemical compound [K+].[K+].[O-][W]([O-])(=O)=O AAQNGTNRWPXMPB-UHFFFAOYSA-N 0.000 claims description 7
- 238000004519 manufacturing process Methods 0.000 claims description 6
- VVXLFFIFNVKFBD-UHFFFAOYSA-N 4,4,4-trifluoro-1-phenylbutane-1,3-dione Chemical compound FC(F)(F)C(=O)CC(=O)C1=CC=CC=C1 VVXLFFIFNVKFBD-UHFFFAOYSA-N 0.000 claims description 5
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims description 5
- 229910021380 Manganese Chloride Inorganic materials 0.000 claims description 5
- GLFNIEUTAYBVOC-UHFFFAOYSA-L Manganese chloride Chemical compound Cl[Mn]Cl GLFNIEUTAYBVOC-UHFFFAOYSA-L 0.000 claims description 5
- 239000000654 additive Substances 0.000 claims description 5
- 230000000996 additive effect Effects 0.000 claims description 5
- 239000011575 calcium Substances 0.000 claims description 5
- KSYURTCLCUKLSF-UHFFFAOYSA-H disodium;hexafluorozirconium(2-) Chemical compound [F-].[F-].[F-].[F-].[F-].[F-].[Na+].[Na+].[Zr+4] KSYURTCLCUKLSF-UHFFFAOYSA-H 0.000 claims description 5
- 229910052744 lithium Inorganic materials 0.000 claims description 5
- 235000002867 manganese chloride Nutrition 0.000 claims description 5
- 239000011565 manganese chloride Substances 0.000 claims description 5
- 239000012286 potassium permanganate Substances 0.000 claims description 5
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 4
- 239000004115 Sodium Silicate Substances 0.000 claims description 4
- 229910052791 calcium Inorganic materials 0.000 claims description 4
- OJLGWNFZMTVNCX-UHFFFAOYSA-N dioxido(dioxo)tungsten;zirconium(4+) Chemical compound [Zr+4].[O-][W]([O-])(=O)=O.[O-][W]([O-])(=O)=O OJLGWNFZMTVNCX-UHFFFAOYSA-N 0.000 claims description 4
- 229910002096 lithium permanganate Inorganic materials 0.000 claims description 4
- 239000011734 sodium Substances 0.000 claims description 4
- 229910052911 sodium silicate Inorganic materials 0.000 claims description 4
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 claims description 4
- XMVONEAAOPAGAO-UHFFFAOYSA-N sodium tungstate Chemical compound [Na+].[Na+].[O-][W]([O-])(=O)=O XMVONEAAOPAGAO-UHFFFAOYSA-N 0.000 claims description 4
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 claims description 4
- JYLNVJYYQQXNEK-UHFFFAOYSA-N 3-amino-2-(4-chlorophenyl)-1-propanesulfonic acid Chemical compound OS(=O)(=O)CC(CN)C1=CC=C(Cl)C=C1 JYLNVJYYQQXNEK-UHFFFAOYSA-N 0.000 claims description 3
- 239000004111 Potassium silicate Substances 0.000 claims description 3
- 229910052918 calcium silicate Inorganic materials 0.000 claims description 3
- 239000000378 calcium silicate Substances 0.000 claims description 3
- 235000012241 calcium silicate Nutrition 0.000 claims description 3
- OYACROKNLOSFPA-UHFFFAOYSA-N calcium;dioxido(oxo)silane Chemical compound [Ca+2].[O-][Si]([O-])=O OYACROKNLOSFPA-UHFFFAOYSA-N 0.000 claims description 3
- PAZHGORSDKKUPI-UHFFFAOYSA-N lithium metasilicate Chemical compound [Li+].[Li+].[O-][Si]([O-])=O PAZHGORSDKKUPI-UHFFFAOYSA-N 0.000 claims description 3
- 229910052912 lithium silicate Inorganic materials 0.000 claims description 3
- 229910052919 magnesium silicate Inorganic materials 0.000 claims description 3
- 239000000391 magnesium silicate Substances 0.000 claims description 3
- 235000019792 magnesium silicate Nutrition 0.000 claims description 3
- 229940099607 manganese chloride Drugs 0.000 claims description 3
- 229910052913 potassium silicate Inorganic materials 0.000 claims description 3
- NNHHDJVEYQHLHG-UHFFFAOYSA-N potassium silicate Chemical compound [K+].[K+].[O-][Si]([O-])=O NNHHDJVEYQHLHG-UHFFFAOYSA-N 0.000 claims description 3
- 235000019353 potassium silicate Nutrition 0.000 claims description 3
- 235000019794 sodium silicate Nutrition 0.000 claims description 3
- 150000003657 tungsten Chemical class 0.000 claims description 3
- 229910020148 K2ZrF6 Inorganic materials 0.000 claims description 2
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims 1
- ZADYMNAVLSWLEQ-UHFFFAOYSA-N magnesium;oxygen(2-);silicon(4+) Chemical compound [O-2].[O-2].[O-2].[Mg+2].[Si+4] ZADYMNAVLSWLEQ-UHFFFAOYSA-N 0.000 claims 1
- -1 manganese salt tungstate Chemical class 0.000 claims 1
- 238000005260 corrosion Methods 0.000 description 31
- 239000010410 layer Substances 0.000 description 26
- 230000007797 corrosion Effects 0.000 description 19
- 230000003647 oxidation Effects 0.000 description 17
- 238000007254 oxidation reaction Methods 0.000 description 17
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 description 9
- 239000011572 manganese Substances 0.000 description 7
- 238000005554 pickling Methods 0.000 description 6
- 238000002791 soaking Methods 0.000 description 6
- 238000000151 deposition Methods 0.000 description 5
- 239000002253 acid Substances 0.000 description 4
- JOPOVCBBYLSVDA-UHFFFAOYSA-N chromium(6+) Chemical compound [Cr+6] JOPOVCBBYLSVDA-UHFFFAOYSA-N 0.000 description 4
- 230000008021 deposition Effects 0.000 description 4
- 239000004519 grease Substances 0.000 description 4
- 239000011148 porous material Substances 0.000 description 4
- PNEYBMLMFCGWSK-UHFFFAOYSA-N Alumina Chemical class [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 3
- 229910007786 Li2WO4 Inorganic materials 0.000 description 3
- 239000011248 coating agent Substances 0.000 description 3
- 238000000576 coating method Methods 0.000 description 3
- 230000009931 harmful effect Effects 0.000 description 3
- 230000007774 longterm Effects 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 229910019979 (NH4)2ZrF6 Inorganic materials 0.000 description 2
- 229910020494 K2WO4 Inorganic materials 0.000 description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 229910019142 PO4 Inorganic materials 0.000 description 2
- 239000010949 copper Substances 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 238000007654 immersion Methods 0.000 description 2
- 229910000765 intermetallic Inorganic materials 0.000 description 2
- HCWCAKKEBCNQJP-UHFFFAOYSA-N magnesium orthosilicate Chemical compound [Mg+2].[Mg+2].[O-][Si]([O-])([O-])[O-] HCWCAKKEBCNQJP-UHFFFAOYSA-N 0.000 description 2
- 229910001092 metal group alloy Inorganic materials 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 2
- 239000011241 protective layer Substances 0.000 description 2
- 239000007921 spray Substances 0.000 description 2
- 239000008399 tap water Substances 0.000 description 2
- 235000020679 tap water Nutrition 0.000 description 2
- 229910004829 CaWO4 Inorganic materials 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910014689 LiMnO Inorganic materials 0.000 description 1
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 1
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 1
- 229910020489 SiO3 Inorganic materials 0.000 description 1
- 229910052783 alkali metal Inorganic materials 0.000 description 1
- 229910052784 alkaline earth metal Inorganic materials 0.000 description 1
- 150000001342 alkaline earth metals Chemical class 0.000 description 1
- WNROFYMDJYEPJX-UHFFFAOYSA-K aluminium hydroxide Chemical compound [OH-].[OH-].[OH-].[Al+3] WNROFYMDJYEPJX-UHFFFAOYSA-K 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 238000013475 authorization Methods 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910001593 boehmite Inorganic materials 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 150000001844 chromium Chemical class 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000000975 dye Substances 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
- 238000000921 elemental analysis Methods 0.000 description 1
- 150000004679 hydroxides Chemical class 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- 238000002386 leaching Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 239000003921 oil Substances 0.000 description 1
- 239000012044 organic layer Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 238000010422 painting Methods 0.000 description 1
- 239000010452 phosphate Substances 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
- 239000011591 potassium Substances 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000002203 pretreatment Methods 0.000 description 1
- 150000004760 silicates Chemical class 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 238000005211 surface analysis Methods 0.000 description 1
- 229910052726 zirconium Inorganic materials 0.000 description 1
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
- C25D11/06—Anodisation of aluminium or alloys based thereon characterised by the electrolytes used
- C25D11/08—Anodisation of aluminium or alloys based thereon characterised by the electrolytes used containing inorganic acids
-
- 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
-
- 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
- C25D11/16—Pretreatment, e.g. desmutting
Definitions
- DESCRIPTION TITLE PROCESS FOR POST-ANODIZATION SEALING OF ALUMINUM AND ALUMINUM ALLOYS WITHOUT USING CHROME
- the present invention is part of the search for new solutions for anti-corrosion protection of the aluminum or aluminum alloys, particularly for aeronautical applications, with or without application of a paint system.
- the process of the invention makes it possible to obtain a coating having very high anti-corrosion properties on aluminum or aluminum alloys, without using chromium.
- Technical background includes in particular documents US-A1-2002/117,236, US-A1-2006/191,599, US-B-6,663,700, US-A1-2016/047,057 and WO-A1 - 2013/117767.
- Aluminum alloys are materials of choice for the transport industry, and more particularly for the aeronautics industry, due to their excellent mechanical properties/weight ratio and their relatively low manufacturing cost. However, these alloys are likely, depending on the environment in which they are found, to be affected by several types of localized corrosion, causing degradation of the part and potentially leading to its removal or failure. Many strategies have been implemented to overcome this weakness, and, among them, the formation or deposition of a protective layer on the surface of alloys is the most used. This is particularly the case for protective layers obtained by the anodizing process for aluminum alloys. Anodizing is an electrolytic process aimed at replacing the natural oxide (native oxide), of a few nanometers which covers the aluminum, with an oxide layer of up to several micrometers.
- the oxide layers produced by anodization have a thickness that can range from two microns to around fifteen microns, in order to provide protection against long-term corrosion.
- Anodizing also called anodic oxidation, therefore consists of forming a layer of porous aluminum oxides/hydroxides called a layer on the surface of the part. anodic, by applying a current to the part immersed in an electrolytic bath containing a strong acid type electrolyte, the part constituting the anode of the electrolytic system.
- the layer thus formed on the surface of the part after a sealing treatment, makes it possible to reinforce the corrosion resistance of the part.
- Anodizing treatments are now commonly used in the aeronautics industry, mainly to improve the corrosion resistance of parts, and therefore their lifespan, but also to facilitate the adhesion of organic layers (paints).
- the anodizing process is directly impacted by European regulations (REACH), which, since September 2017, has prohibited (or restricted to authorization) the use of certain key components in surface treatments, in particular, hexavalent chromium.
- hexavalent chromium is present in the OAC type anodizing treatment (Chromic Anodic Oxidation as described, for example, in www.a3ts.org/actualite/commissions-techniques/fiches-techniques-traitement- surface/anodisation- chromic, but also in the usual surface preparation pretreatments, aimed at cleaning/stripping the surfaces of the parts before the anodizing treatment, and finally in the final so-called sealing treatments, the objective of which is to close the pores of the anodic layer formed during the anodizing treatment.
- OAC can also be replaced by OAS NG FE (new generation thin thickness sulfuric anodic oxidation) which is an OAS NG type anodizing whose anodizing parameters (Voltage , Immersion time) were adapted to obtain an anodizing layer whose thickness is between 2 and 7 ⁇ m.
- OAS NG FE new generation thin thickness sulfuric anodic oxidation
- anodizing parameters Voltage , Immersion time
- FR 3106838B1 offers a post-anodization sealing process for aluminum or aluminum alloy which makes it possible to improve the corrosion resistance of the part without using hexavalent chromium impacted by European REACH regulations.
- This process which is also suitable for so-called “difficult” aluminum alloys, comprises a step of impregnating the aluminum or the aluminum alloy in an aqueous bath containing a hexaflurozirconate salt and a trivalent chromium salt followed by a sealing step carried out in an aqueous solution comprising an alkali metal or alkaline earth metal silicate.
- aqueous solution comprising an alkali metal or alkaline earth metal silicate.
- the present invention aims precisely to meet these needs, in particular, in terms of corrosion resistance of aluminum alloys, in particular of the 2xxx, 6xxx and 7xxx series, of aluminum foundry alloys.
- a post-anodization sealing process for aluminum or aluminum alloy comprising at least the following steps: A) a step of impregnating the aluminum or the anodized aluminum alloy, in an aqueous bath of demineralized water containing • a hexafluorozirconate salt chosen from the group consisting of ammonium hexafluorozirconate ((NH4)2ZrF6), sodium hexafluorozirconate (Na 2 ZrF 6 ), potassium hexafluorozirconate (K 2 ZrF 6 ), and • a di-, tri, tetra
- the hexafluorozirconate salt concentration is between 0.5 and 50 g/L.
- the concentration of manganese salt in this step is between 0.1 and 50 g/L.
- Intermediate rinses, in particular with demineralized water, are preferably carried out - between steps A) and B), and/or - before and/or after the treatment of the part by anodization.
- the anodizing layers have a very porous structure, when chemical and/or corrosion resistance is essential, the anodizing layer must be sealed. This implies that the aluminum oxide layer is transformed into an aluminum hydroxide complex where the pores are sealed.
- sealing in addition to anodizing, is decisive for the quality of the anodizing layer because: • sealing the pores leads to an increase in corrosion resistance; • clogging is avoided; • leaching of dyes out of the pores is avoided.
- the post-anodization sealing process of the invention makes it possible to obtain a coating having very high anti-corrosion properties on so-called difficult aluminum alloys such as, for example, 2618A and 2214, but also on the most difficult aluminum alloys. more common in the aeronautical field, such as the 2024 or the 7175 for example.
- the sealing process of the invention can be applied to different anodizations known to those skilled in the art, among which we can cite OAST, OAS NG FE, OAS NG.
- the process of the invention demonstrates the possibility of using other types of chrome-free impregnation layers making it possible to deposit the silicate on the surface, such as for example a Mn/Zr impregnation.
- a sulfuric anodization is composed of a layer of aluminum oxide
- the inventors sought to know a) if it was possible to deposit silicate on a chrome-free impregnation layer, for example a layer of 'Mn/Zr impregnation instead of Cr III /Zr, and b) if yes, if this deposition would improve the corrosion resistance of the chrome-free impregnation layer, for example a Mn/Zr impregnation layer, as is the case for a Cr III /Zr impregnation layer.
- the invention also relates to a method for surface treatment of a part made of aluminum or aluminum alloy intended to be used in the aeronautics sector comprising at least the following steps: i) subjecting said part to an anodizing step , possibly having previously undergone a surface preparation step (degreasing, then stripping); ii) treatment of the anodized part by a post-anodization sealing process according to the invention; and possibly iii) application of one or more coat(s) of paint.
- Another object of the invention is the use of a post-anodization sealing process according to the invention, in the surface treatment of aluminum or aluminum alloy parts intended for the aeronautical sector.
- FIG.1 Figure 1 represents a theoretical diagram comparing the deposition of species on the anodization layer (OA) by the sealing process described in FR3106838B1 and by the sealing process of the invention.
- the present invention aims precisely to meet the needs of the state of the art, in particular, in terms of corrosion resistance of aluminum alloys, in particular of the 2xxx, 6xxx and 7xxx series, of foundry alloys, and aluminum alloys from processes such as additive manufacturing and so-called difficult aluminum alloys, by providing a process for post-anodization sealing of aluminum or aluminum alloy, comprising at least the following steps: A) a step of impregnating the aluminum or the anodized aluminum alloy, in an aqueous bath of demineralized water containing • a hexafluorozirconate salt chosen from the group consisting of ammonium hexafluorozirconate ((NH 4 ) 2 ZrF 6 ), sodium hexafluorozirconate (Na 2 ZrF 6 ), potassium hexafluorozirconate (K 2 ZrF 6 ), and • a di-, tri-, tetra-, or hepta-
- the di-, tri-, tetra-, or hepta-valent manganese salt may be, for example, one of the following commercial products: Bonderite M-ED160/161.
- the tungstate salt may be, for example, one of the following commercial products: lithium tungstate (Li2WO4), sodium tungstate (Na2WO4), potassium tungstate (K 2 WO 4 ), calcium tungstate (CaWO 4) , ammonium tungstate tungstate potassium ((NH 4 ) 10 H 2 (W 2 O 7 ) 6 ) from the Sigma Aldrich brand from the company Merck, and zirconium tungstate (Zr(WO4)2) from the company Fisher Scientific.
- Intermediate rinses are preferably carried out - between steps A) and B), and/or - before and/or after the treatment of the part by anodization.
- the optimized sealing process of the invention can be suitable for any type of aluminum alloys including so-called “difficult” alloys, in particular aluminum alloys of the 2xxx, 6xxx and 7xxx series, previously anodized by different processes, for example for example, by the OAST (sulfo-tartaric anodic oxidation), OAS NG FE (new generation thin thickness anodic sulfuric oxidation) or OAS NG (new generation sulfuric anodic oxidation) processes.
- OAST sulfo-tartaric anodic oxidation
- OAS NG FE new generation thin thickness anodic sulfuric oxidation
- OAS NG new generation sulfuric anodic oxidation
- the post-anodization sealing process of the invention is compatible with the requirements associated with the European REACH regulation and leads to good anti-corrosion protection on so-called “difficult” aluminum alloys (for example, 2618A, 2214 and AU5NKZr). This process may or may not be followed by an application of paint.
- the post-anodization sealing process of the invention makes it possible to obtain a coating having very high anti-corrosion properties on aluminum alloys of the 2xxx, 6xxx and 7xxx series and difficult aluminum alloys, but also on most common aluminum alloys in the aeronautical field, such as 2024 and 7175 and so-called “difficult” aluminum alloys such as 2618A and 2214.
- the process of the invention is suitable, more particularly, for aluminum and aluminum alloy parts of the 2xxx, 6xxx and 7xxx series, in particular selected from the group consisting of 2014, 2017, 2024, 2214, 2219, 2618, AU5NKZr, 7175, 5052, 5086, 6061, 6063, 7010, 7020 , 7050, 7050 T7451, 7055, 7068, 7085, 7075, 7175 and 7475, aluminum foundry alloys type AS7G06, AS7G03, AS10G and AS9U3, aluminum alloys from processes such as additive manufacturing.
- the concentration of hexafluorozirconate salt is between 0.5 and 50 g/L, for example equal to 2 g/L.
- the concentration of di-, tri-, tetra-, or hepta-valent manganese salt, or tungstate salt in this step is between 0.1 and 50 g/L, for example equal to 1 g/L.
- the temperature of the bath in step A) can be between 20 and 80°C, preferably between 20 and 60°C, more preferably between 35 and 60°C, for example between 35 and 45°C.
- the pH of the bath in step A) is between 3 and 5, preferably between 3.5 and 4.5, for example between 3.7 and 4.2.
- the duration of the impregnation in the bath in step A) is between 1 and 40 minutes, preferably between 5 and 30 minutes, for example between 5 and 20 minutes.
- the impregnation step A) is followed by a step B) which is a sealing step.
- the clogging of step B) is carried out in an aqueous solution of deionized water having a conductivity less than or equal to 200 ⁇ S/cm, preferably between 1 and 100 ⁇ S/cm, for example between 1 and 50 ⁇ S/ cm.
- the temperature of the aqueous solution of step B) is preferably between 80 and 100°C, for example between 80 and 98°C.
- the alkali metal or alkaline earth metal silicate may be selected from the group consisting of lithium silicate, sodium silicate, potassium silicate, calcium silicate and magnesium silicate.
- the concentration of alkali metal or alkaline earth metal silicate in the solution is preferably between 1 and 500 g/L, for example between 5 and 100 g/L.
- the duration of the clogging step B) is between 1 and 40 minutes, preferably between 5 and 35 minutes, for example between 5 and 30 minutes.
- the pH of the sealing solution is between 9 and 12, preferably between 10 and 11.5 minutes, for example between 10.5 and 11.4.
- the clogging is followed by a rinsing step C) in deionized water having a conductivity less than or equal to 100 ⁇ S/cm, preferably between 1 and 100 ⁇ S/cm, more preferably between 10 and 100 ⁇ S/cm per example between 10 and 50 ⁇ S/cm.
- Post-clogging rinsing is preferably carried out at a temperature between 10 and 75°C, for example between 15 and 60°C.
- the pH of the water in step C) is between 4.5 and 8.5, preferably between 5 and 8, for example between 5.5 and 7.5.
- the duration of the post-clogging rinse is between 10 seconds and 10 minutes, preferably between 10 seconds and 5 minutes, for example between 30 seconds and 2 minutes.
- the quality of the water used is important for the success of the operation, with certain impurities being known to be harmful at very low levels (for example, Ca 2+ , Cu 2+ , Fe 2+ , F-, Cl-, SiO3 -, PO4 3- ).
- impurities for example, Ca 2+ , Cu 2+ , Fe 2+ , F-, Cl-, SiO3 -, PO4 3- .
- the treatment time is approximately 2.5 min/ ⁇ m (close to the anodizing time).
- This operation is a partial thermohydration of the alumina which crystallizes into monohydrated alumina (Böhmite).
- the aluminum or aluminum alloy Before subjecting the aluminum or aluminum alloy to the anodizing step, the aluminum or aluminum alloy may be subjected to a surface preparation step by degreasing and/or pickling in order to remove grease, dirt and oxides present on its surface.
- This preliminary surface preparation step may include one or more of the following operations: - solvent degreasing, to dissolve grease present on the surface of the aluminum or aluminum alloy. This operation can be carried out by soaking, sprinkling, or any other method known to those skilled in the art; - alkaline degreasing, to dissolve grease present on the surface of aluminum or aluminum alloy.
- This operation can be carried out by soaking, sprinkling, or any other technique known to those skilled in the art; - alkaline stripping, to dissolve the oxides naturally formed on the surface of aluminum or aluminum alloy.
- This operation can be carried out by soaking, sprinkling, or any other technique known to those skilled in the art.
- the aluminum or aluminum alloy is covered with a powdery layer formed of oxidation products of the intermetallic compounds, which must be eliminated by an acid pickling step; - acid pickling, to dissolve the oxides naturally formed on the surface of the aluminum or aluminum alloy, and/or the oxidation layer formed on the surface of the part during the alkaline pickling step.
- This operation can be carried out by soaking, sprinkling, or any other technique known to those skilled in the art.
- the preliminary step of surface preparation of the aluminum or aluminum alloy by degreasing and/or pickling to eliminate grease, dirt and oxides present on its surface can be carried out under the conditions described, for example, in application WO 2013/117759.
- Intermediate rinses, in particular with demineralized water, are preferably carried out between the successive stages above, and before treatment of the part by anodization.
- the aluminum or aluminum alloy optionally subjected to a surface preparation step by degreasing and/or pickling by one or more of the operations described above , is anodized.
- OAS Anodic Sulfuric Oxidation (clogging based on Chromium VI, process impacted by European REACH regulations), • OAC: Chromic Anodic Oxidation (Based on Chromium VI, process impacted by European REACH regulations) , • OAST: SulfoTartaric Anodic Oxidation, • OAST: SulfoTartaric Anodic Oxidation, • OAS NG FE: New Generation Sulfuric Anodic Oxidation Fine Thickness, • OAS NG: New Generation Sulfuric Anodic Oxidation.
- the OAST LC, OAS NG FE, OAS NG anodizing processes are preferred.
- the surface treatment process of the invention significantly improves the corrosion resistance properties of metal or metal alloy parts, in particular aluminum or aluminum alloy parts and complies with the requirements of the European REACH regulations.
- the process of the invention is of great interest in any type of industry where one seeks to improve the corrosion resistance properties of parts made of metal or a metal alloy, in particular parts made of aluminum or an aluminum alloy, such as in aeronautics, automobiles, the oil industry, etc.
- the method according to the invention may comprise one or more of the following characteristics and/or steps, taken in isolation from each other or in combination with each other: - the aluminum alloy is an aluminum alloy of the 2xxx series , 6xxx and 7xxx, in particular chosen from the group consisting of 2014, 2017, 2024, 2214, 2219, 2618, AU5NKZr, 7175, 5052, 5086, 6061, 6063, 7010, 7020, 7050, 7050 T7451, 7055, 7068, 7085 , 7075, 7175 and 7475, aluminum foundry alloys type AS7G06, AS7G03, AS10G and AS9U3, aluminum alloys from processes such as additive manufacturing; - in impregnation step A), the hexafluorozirconate salt concentration is between 0.5 and 50 g/L; - in the impregnation step A), the concentration of di-, tri-, tetra-, or hepta-valent manganese salt, or tungstate
- the process of the invention makes it possible to obtain corrosion resistance similar to chromated anodizing without the use of chrome. It makes it possible to find an innovative sealing solution for the anodization of aluminum alloys, thus meeting the specifications for corrosion resistance and paint adhesion without using chrome.
- the invention also relates to a method for surface treatment of a part made of aluminum or aluminum alloy intended to be used in the aeronautics sector comprising at least the following steps: i) subjecting said part to an anodizing step , possibly having previously undergone a surface preparation step (degreasing, then stripping); ii) treatment of the anodized part by a post-anodization sealing process according to the invention; and possibly iii) application of one or more coat(s) of paint.
- Another object of the invention is the use of a post-anodization sealing process according to the invention, in the surface treatment of aluminum or aluminum alloy parts intended for the aeronautical sector.
- the invention also relates to a part made of aluminum or aluminum alloy treated by a post-anodization sealing process according to the invention, possibly comprising one or more layers of paint and intended for the aeronautical sector.
- Anodizing treatment followed by a paint application certain aeronautical parts have a paint treatment after anodizing in order to reinforce anti-corrosion protection.
- the invention is compatible with different painting systems. Other advantages and characteristics of the invention will appear on reading the examples below given for illustration.
- Example 1 Method of anodizing of aluminum alloy parts Parts of 2618 T6 aluminum alloy with dimensions 120x100x5 mm are treated according to the methods described below. Surface preparation steps for the part are first carried out successively: - alkaline degreasing, by soaking the part in a solution of SOCOCLEAN A3431 at 11% by volume, at a temperature of 45°C, for 10 minutes; - rinsing with tap water or demineralized water; - acid stripping by soaking the part in a mixture of SOCOSURF A1858 at 42% by volume and SOCOSURF A1806 at 10% by volume at a temperature of 50°C for 10 minutes; - rinsing with tap water or demineralized water.
- the stripped and rinsed parts are then subjected to a new generation sulfuric anodizing process (standard thickness or fine thickness (FE)).
- the operating parameters for anodizing are indicated in table 1 below.
- Table 1 The anodized parts according to the invention are then subjected to the sealing process in accordance with the invention under the conditions and in the order indicated below in: - step A): a step of impregnation of said parts, successively, in an aqueous bath of BONDERITE M-ED 160/161 (15g/L ED160 and 18g/L ED161) at a temperature of 40°C for 10 minutes and at a pH of 3.9, then - step B): sealing by immersion of the parts at the end an aqueous solution of deionized water having a conductivity less than 100 ⁇ S/cm with 80g/L of a sodium silicate, a temperature of 100°C and for 10 minutes; - step C): post-clogging rinsing by immersing the parts after
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Abstract
The invention relates to a method for post-anodisation sealing of aluminium or aluminium alloy without using chromium. The invention also relates to a method for treating the surface of a part made of aluminium or aluminium alloy intended for use in the aviation sector, including at least the following steps: i) subjecting the part to an anodisation step; ii) treating the anodised part by a post-anodisation sealing method according to the invention; and optionally iii) applying one or more coat(s) of paint. The invention also relates to a part made of aluminium or aluminium alloy treated by a post-anodisation sealing method according to the invention, optionally including one or more coat(s) of paint.
Description
DESCRIPTION TITRE : PROCEDE DE COLMATAGE POST-ANODISATION DE L’ALUMINIUM ET DES ALLIAGES D’ALUMINIUM SANS UTILISER DE CHROME Domaine technique de l'invention La présente invention s’inscrit dans le cadre de la recherche de nouvelles solutions de protection anticorrosion de l’aluminium ou des alliages d'aluminium, notamment pour applications aéronautiques, avec ou sans application d’un système de peinture. En particulier, le procédé de l’invention permet d’obtenir un revêtement ayant des propriétés anticorrosion très élevées sur l’aluminium ou les alliages d'aluminium, sans utiliser de chrome. Arrière-plan technique L’arrière-plan technique comprend notamment les documents US-A1-2002/117 236, US-A1-2006/191 599, US-B-6,663,700, US-A1-2016/047 057 et WO-A1- 2013/117767. Les alliages d’aluminium sont des matériaux de choix pour l’industrie des transports, et plus particulièrement pour l’industrie aéronautique, du fait de leur excellent rapport propriétés mécaniques/poids et de leur coût de fabrication qui est relativement faible. Cependant, ces alliages sont susceptibles, suivant le milieu dans lequel ils se trouvent, d’être affectés par plusieurs types de corrosion localisée, engendrant la dégradation de la pièce et pouvant amener à son retrait ou à sa défaillance. De nombreuses stratégies ont été mises en œuvre afin de pallier cette faiblesse, et, parmi elles, la formation ou le dépôt d’une couche protectrice à la surface des alliages est celle la plus utilisée. C’est le cas notamment des couches de protection obtenues par le procédé d’anodisation des alliages d’aluminium. L’anodisation est un procédé électrolytique visant à substituer l’oxyde naturel (oxyde natif), de quelques nanomètres qui recouvre l’aluminium, par une couche d’oxyde pouvant aller jusqu’à plusieurs micromètres. Les couches d’oxyde produites par anodisation ont une épaisseur pouvant aller de deux microns à une quinzaine de microns, en vue d’apporter une protection contre la corrosion à long terme. L’anodisation, également nommée oxydation anodique, consiste donc à former en surface de la pièce une couche d’oxydes/hydroxydes d’aluminium poreuse dite couche
anodique, par application d’un courant à la pièce immergée dans un bain électrolytique contenant un électrolyte de type acide fort, la pièce constituant l’anode du système électrolytique. La couche ainsi formée en surface de la pièce, après un traitement de colmatage, permet de renforcer la tenue à la corrosion de la pièce. Les traitements d’anodisation sont aujourd’hui couramment utilisés dans l’industrie aéronautique, principalement pour améliorer la tenue à la corrosion des pièces, et donc leur durée de vie, mais aussi pour faciliter l’accroche de couches organiques (peintures). Cependant, le procédé de l’anodisation, est directement impacté par la réglementation européenne (REACH), qui, depuis septembre 2017, interdit (ou restreint à autorisation) l’utilisation de certains composants clés dans les traitements de surface, en particulier, le chrome hexavalent. Or, le chrome hexavalent est présent dans le traitement d’anodisation de type OAC (Oxydation Anodique Chromique telle que décrite, par exemple, dans www.a3ts.org/actualite/commissions-techniques/fiches-techniques-traitement- surface/anodisation-chromique, mais aussi dans les prétraitements usuels de préparation de surface, visant à nettoyer/décaper les surfaces des pièces avant le traitement d’anodisation, et enfin dans les traitements finaux dits de colmatage, dont l’objectif est de refermer les pores de la couche anodique formée lors du traitement d’anodisation. Différents procédés ont donc été proposés pour substituer les traitements d’OAC et d’OAS (Oxydation Anodique Sulfurique) colmatés au chrome hexavalent, impactés par la réglementation européenne REACH: • l’OAS NG (oxydation anodique sulfurique nouvelle génération telle que décrite par exemple dans www.a3ts.org/actualite/commissions-techniques/fiches-techniques- traitement-surface/anodisation-sulfurique-version-5-2) a été proposée pour remplacer l’OAS ; • l’OAST (oxydation anodique sulfo-tartrique telle que décrite, par exemple, dans www.a3ts.org/actualite/commissions-techniques/fiches-techniques-traitement- surface/anodisation-sulfo-tartrique-oast-tartric-sulfuric-anodizing-tsa a été proposée pour remplacer l’OAC. L’OAC peut également être remplacée par l’OAS NG FE (oxydation anodique sulfurique nouvelle génération fine épaisseur) qui est une anodisation de type OAS NG dont les paramètres d’anodisation (Tension, Temps d’immersion) ont été adaptés pour obtenir une couche d’anodisation dont l’épaisseur est comprise entre 2 et 7 µm.
Bien que les solutions d'anodisation classiques actuelles, comme par exemple l’OAS NG suivie d'un colmatage à l'eau chaude, mettent en œuvre des gammes de traitements compatibles avec la réglementation européenne REACH, elles restent néanmoins peu ou pas satisfaisantes en termes de protection anticorrosion sur certaines nuances d’alliages d’aluminium dits « difficiles ». A titre d’exemple non limitatif d’alliages d’aluminium dits « difficiles », on peut citer les alliages 2214, 2618A ou AU5NKZr. Ces alliages possèdent des microstructures particulières de par leur composition chimique, qui leur confèrent soit des défauts de type fonderie, soit des précipités tels que des intermétalliques riches en cuivre ou en fer ou en nickel, etc. Ainsi, lorsque la couche anodique se forme à la surface de ces alliages, des défauts de couches peuvent résider, entraînant certaines fragilités locales sensibles à la corrosion. Pour ces alliages, il est donc nécessaire d’optimiser les gammes d’anodisation afin d’améliorer les performances anticorrosion. FR 3106838B1 propose un procédé de colmatage post-anodisation de l’aluminium ou de l’alliage d’aluminium qui permet d’améliorer la tenue à la corrosion de la pièce sans utiliser du chrome hexavalent impactés par la réglementation européenne REACH. Ce procédé qui convient également aux alliages d’aluminium dits « difficiles », comprend une étape d’imprégnation de l’aluminium ou de l’alliage d’aluminium dans un bain aqueux contenant un sel d’hexaflurozirconate et un sel de chrome trivalent suivi d’une étape de colmatage réalisée dans une solution aqueuse comprenant un silicate de métal alcalin ou de métal alcalinoterreux. Malgré l’amélioration des performances anticorrosion apportée par ce procédé, il existe un risque d’obsolescence à long terme du Cr trivalent. En effet, l’étape d’imprégnation CrIII/Zr qui est obligatoire pour permettre à l’étape de colmatage silicate de s’effectuer, peut être soumise à obsolescence (à cause du chrome) dans le futur avec le durcissement des réglementations environnementales. Pour empêcher l’obsolescence à long terme du Cr trivalent et pour pouvoir se conformer au futur durcissement des réglementations environnementales, il est nécessaire d’optimiser le procédé de colmatage de l’aluminium ou des alliages d’aluminium anodisés notamment en évitant l’utilisation du chrome. Il existe donc un réel besoin d’un procédé de colmatage de l’aluminium ou de l’alliage d’aluminium y compris des alliages d’aluminium dits « difficiles » anodisés, n’utilisant pas de chrome.
En particulier, il existe un réel besoin d’un procédé de colmatage post-anodisation tel que décrit ci-dessus, qui confère de bonnes performances anticorrosion de l’aluminium ou de l’alliage d’aluminium y compris des alliages d’aluminium dits « difficiles », tout en se conformant aux exigences de la règlementation actuelle et future REACH. Résumé de l'invention La présente invention a précisément pour but de répondre à ces besoins, en particulier, en termes de résistance à la corrosion des alliages d’aluminium, notamment des séries 2xxx, 6xxx et 7xxx, des alliages de fonderie d’aluminium tels que AS7G06, AS7G03, AS10G ou AS9U3, des alliages d’aluminium issus de procédés tels que la fabrication additive, et des alliages d’aluminium dits difficiles, en fournissant un procédé de colmatage post-anodisation de l’aluminium ou de l’alliage d'aluminium, comportant au moins les étapes suivantes : A) une étape d’imprégnation de l’aluminium ou de l’alliage d'aluminium anodisé, dans un bain aqueux d’eau déminéralisée contenant • un sel d’hexafluorozirconate choisi dans le groupe consistant en hexafluorozirconate d’ammonium ((NH4)2ZrF6), hexafluorozirconate de sodium (Na2ZrF6), hexafluorozirconate de potassium (K2ZrF6), et • un sel de manganèse di-, tri, tétra, ou hepta-valent choisi dans le groupe consistant en permanganate de lithium (LiMnO4), permanganate de sodium (NaMnO4), permanganate de potassium (KMnO4), permanganate d’ammonium (NH4MnO4), chlorure de manganèse (MnCl2(H2O)x, où la valeur de x est 0, 2 ou 4), ou • un sel d’hexafluorozirconate choisi dans le groupe consistant en hexafluorozirconate d’ammonium ((NH4)2ZrF6), hexafluorozirconate de sodium (Na2ZrF6), hexafluorozirconate de potassium (K2ZrF6), et • un sel de tungstène choisi dans le groupe consistant en tungstate de lithium (Li2WO4), tungstate de sodium (Na2WO4), tungstate de potassium (K2WO4), tungstate de calcium (CaWO4), tungstate de zirconium (Zr(WO4)2), tungstate d’ammonium tungstate de potassium ((NH4)10H2(W2O7)6), à une température comprise entre 20 et 80°C ; B) une étape de colmatage réalisée dans une solution aqueuse d’eau déionisée ayant une conductivité inférieure ou égale à 100 µS/cm contenant entre 1 et 500 g/L d’un silicate
de métal alcalin ou de métal alcalinoterreux, à une température comprise entre 60 et 100°C ; C) une étape de rinçage post-colmatage dans une eau déionisée ayant une conductivité inférieure ou égale à 100 µS/cm et à une température comprise entre 15 et 75°C. Dans l’étape d’imprégnation A), la concentration en sel d’hexafluorozirconate est comprise entre 0,5 et 50 g/L. La concentration en sel de manganèse dans cette étape est comprise entre 0,1 et 50 g/L. Des rinçages intermédiaires, notamment à l’eau déminéralisée, sont de préférence réalisés - entre les étapes A) et B), et/ou - avant et/ou après le traitement de la pièce par anodisation. Comme les couches d'anodisation présentent une structure très poreuse, lorsque la résistance chimique et /ou à la corrosion est primordiale, il faut colmater la couche d'anodisation. Cela implique que la couche d'oxyde d'aluminium est transformée en un complexe d'hydroxyde d'aluminium où les pores sont obturés. Par conséquent, le colmatage, en plus de l'anodisation, est déterminant pour la qualité de la couche d'anodisation car : • l'obturation des pores entraîne une augmentation de la résistance à la corrosion ; • l'encrassement est évité ; • le lessivage de colorants hors des pores est évité. Le procédé de colmatage post-anodisation de l’invention permet d’obtenir un revêtement ayant des propriétés anticorrosion très élevées sur les alliages d’aluminium dits difficiles comme par exemple, le 2618A et le 2214, mais également sur les alliages d’aluminium les plus courants dans le domaine aéronautique, tels que le 2024 ou le 7175 par exemple. Le procédé de colmatage de l’invention peut être appliqué sur différentes anodisations connues de l’homme du métier parmi lesquelles on peut citer OAST, OAS NG FE, OAS NG. Il peut être suivi ou non d’une application de peinture. Le procédé de l’invention démontre la possibilité d’utiliser d’autres types de couches d’imprégnations sans chrome permettant de déposer le silicate à la surface, comme par exemple une imprégnation Mn/Zr.
Sachant qu’une anodisation sulfurique est composé d’une couche d’oxyde d’aluminium, les inventeurs ont cherché à savoir a) s’il était possible de déposer du silicate sur une couche d’imprégnation sans chrome, par exemple une couche d’imprégnation Mn/Zr à la place de CrIII/Zr, et b) si oui, si cette déposition améliorerait la tenue à la corrosion de la couche imprégnation sans chrome, par exemple une couche d’imprégnation Mn/Zr, comme c’est le cas pour une couche d’imprégnation CrIII/Zr. L’invention concerne également un procédé de traitement de surface d’une pièce en aluminium ou en alliage d’aluminium destinée à être utilisée dans le secteur aéronautique comportant au moins les étapes suivantes : i) soumission de ladite pièce à une étape d’anodisation, ayant éventuellement subie au préalable une étape de préparation de surface (dégraissage, puis décapage) ; ii) traitement de la pièce anodisée par un procédé de colmatage post-anodisation selon l’invention ; et éventuellement iii) application d’une ou de plusieurs couche(s) de peinture. Un autre objet de l’invention est l’utilisation d’un procédé de colmatage post- anodisation selon l’invention, dans le traitement de surface de pièces en aluminium ou en alliage d’aluminium destinées au secteur aéronautique. L’invention a également pour objet, une pièce en aluminium ou en alliage d’aluminium traitée par un procédé de colmatage post-anodisation selon l’invention, comportant éventuellement une ou plusieurs couches(s) de peintures et destinée au secteur aéronautique. Brève description des figures D'autres caractéristiques et avantages de l'invention apparaitront au cours de la lecture de la description détaillée qui va suivre pour la compréhension de laquelle on se reportera aux dessins annexés dans lesquels : [Fig.1] La figure 1 représente un schéma théorique comparant la déposition des espèces sur la couche d’anodisation (OA) par le procédé de colmatage décrit dans FR3106838B1 et par le procédé de colmatage de l’invention. Description détaillée de l'invention La présente invention a précisément pour but de répondre aux besoins de l’état de la technique, en particulier, en termes de résistance à la corrosion des alliages en aluminium, notamment des séries 2xxx, 6xxx et 7xxx, des alliages de fonderie, et les
alliages d’aluminium issus de procédés tels que la fabrication additive et des alliages d’aluminium dits difficiles, en fournissant un procédé de colmatage post-anodisation de l’aluminium ou de l’alliage d'aluminium, comportant au moins les étapes suivantes : A) une étape d’imprégnation de l’aluminium ou de l’alliage d'aluminium anodisé, dans un bain aqueux d’eau déminéralisée contenant • un sel d’hexafluorozirconate choisi dans le groupe consistant en hexafluorozirconate d’ammonium ((NH4)2ZrF6), hexafluorozirconate de sodium (Na2ZrF6), hexafluorozirconate de potassium (K2ZrF6), et • un sel de manganèse di-, tri, tétra, ou hepta-valent choisi dans le groupe consistant en permanganate de lithium (LiMnO4), permanganate de sodium (NaMnO4), permanganate de potassium (KMnO4), permanganate d’ammonium (NH4MnO4), chlorure de manganèse (MnCl2(H2O)x, où la valeur de x est 0, 2 ou 4), ou • un sel d’hexafluorozirconate choisi dans le groupe consistant en hexafluorozirconate d’ammonium ((NH4)2ZrF6), hexafluorozirconate de sodium (Na2ZrF6), hexafluorozirconate de potassium (K2ZrF6), et • un sel de tungstène choisi dans le groupe consistant en tungstate de lithium (Li2WO4), tungstate de sodium (Na2WO4), tungstate de potassium (K2WO4), tungstate de calcium (CaWO4), tungstate de zirconium (Zr(WO4)2), tungstate d’ammonium tungstate de potassium ((NH4)10H2(W2O7)6), à une température comprise entre 20 et 80°C ; B) une étape de colmatage réalisée dans une solution aqueuse d’eau déionisée ayant une conductivité inférieure ou égale à 100 µS/cm contenant entre 1 et 500 g/L d’un silicate de métal alcalin ou de métal alcalinoterreux, à une température comprise entre 60 et 100°C ; C) une étape de rinçage post-colmatage dans une eau déionisée ayant une conductivité inférieure ou égale à 100 µS/cm et à une température comprise entre 15 et 75°C. Le sel de manganèse di-, tri, tétra, ou hepta-valent, peut être, par exemple, l’un des produits commerciaux suivants : Bonderite M-ED160/161. Le sel de tungstate peut être, par exemple, l’un des produits commerciaux suivants : tungstate de lithium (Li2WO4), tungstate de sodium (Na2WO4), tungstate de potassium (K2WO4), tungstate de calcium (CaWO4), tungstate d’ammonium tungstate de
potassium ((NH4)10H2(W2O7)6) de la marque Sigma Aldrich de la société Merck, et tungstate de zirconium (Zr(WO4)2) de la société Fisher Scientific. Des rinçages intermédiaires, notamment à l’eau déminéralisée, sont de préférence réalisés - entre les étapes A) et B), et/ou - avant et/ou après le traitement de la pièce par anodisation. Le procédé de colmatage optimisé de l’invention peut convenir à tout type d’alliages d’aluminium y compris les alliages dits « difficiles », notamment des alliages d'aluminium des séries 2xxx, 6xxx et 7xxx, préalablement anodisés par différents procédés, par exemple, par les procédés OAST (oxydation anodique sulfo-tartrique), OAS NG FE (oxydation anodique sulfurique nouvelle génération fine épaisseur) ou OAS NG (oxydation anodique sulfurique nouvelle génération). Par ailleurs, le procédé de colmatage post-anodisation de l’invention est compatible avec les exigences associées à la réglementation européenne REACH et conduit à une bonne protection anticorrosion sur les alliages d'aluminium dits « difficiles » (par exemple, 2618A, 2214 et AU5NKZr). Ce procédé peut être suivi ou non d’une application de peinture. Ainsi, le procédé de colmatage post-anodisation de l’invention permet d’obtenir un revêtement ayant des propriétés anticorrosion très élevées sur les alliages d’aluminium des séries 2xxx, 6xxx et 7xxx et les alliages d’aluminium difficiles, mais également sur les alliages d’aluminium les plus courants dans le domaine aéronautique, tels que le 2024 et le 7175 et les alliages d’aluminium dits « difficiles » tels que le 2618A et le 2214. Le procédé de l’invention convient, plus particulièrement, à des pièces en aluminium et alliage d’aluminium des séries 2xxx, 6xxx et 7xxx, notamment choisi dans le groupe consistant en 2014, 2017, 2024, 2214, 2219, 2618, AU5NKZr, 7175, 5052, 5086, 6061, 6063, 7010, 7020, 7050, 7050 T7451, 7055, 7068, 7085, 7075, 7175 et 7475, alliages de fonderie d’aluminium type AS7G06, AS7G03, AS10G et AS9U3, alliages d’aluminiums issus de procédés tels que la fabrication d’additive. Dans l’étape d’imprégnation A), la concentration en sel d’hexafluorozirconate est comprise entre 0,5 et 50 g/L, par exemple égale à 2 g/L. La concentration en sel de manganèse di-, tri, tétra, ou hepta-valent, ou en sel de tungstate dans cette étape est comprise entre 0,1 et 50 g/L, par exemple égale à 1 g/L.
La température du bain l’étape A) peut être comprise entre 20 et 80°C, de préférence comprise entre 20 et 60°C, plus préférentiellement comprise entre 35 et 60°C, par exemple comprise entre 35 et 45°C. Le pH du bain à l’étape A) est compris entre 3 et 5, de préférence compris entre 3,5 et 4,5, par exemple compris entre 3,7 et 4,2. La durée de l’imprégnation, dans le bain à l’étape A) est comprise entre 1 et 40 minutes, de préférence comprise entre 5 et 30 minutes, par exemple comprise entre 5 et 20 minutes. L’étape d’imprégnation A) est suivie d’une étape B) qui est une étape de colmatage. Le colmatage de l’étape B) est réalisé dans une solution aqueuse d’eau déionisée ayant une conductivité inférieure ou égale à 200 µS/cm, de préférence comprise entre 1 et 100 µS/cm, par exemple comprise entre 1 et 50 µS/cm. La température de la solution aqueuse de l’étape B) est de préférence comprise entre 80 et 100°C, par exemple comprise entre 80 et 98°C. Le silicate de métal alcalin ou de métal alcalinoterreux peut être choisi dans le groupe consistant en silicate de lithium, silicate de sodium, silicate de potassium, silicate de calcium et silicate de magnésium. Dans l’étape de colmatage B), la concentration en silicate de métal alcalin ou de métal alcalinoterreux dans la solution est, de préférence, comprise entre 1 et 500g/L, par exemple comprise entre 5 et 100 g/L. La durée de l’étape de colmatage B) est comprise entre 1 et 40 minutes, de préférence comprise entre 5 et 35 minutes, par exemple comprise entre 5 et 30 minutes. Le pH de la solution de colmatage est entre 9 et 12, de préférence entre 10 et et 11,5 minutes, par exemple entre 10,5 et 11,4. Le colmatage est suivi d’une étape de rinçage C) dans une eau déionisée ayant une conductivité inférieure ou égale à 100 µS/cm, de préférence comprise entre 1 et 100 µS/cm, plus préférentiellement comprise entre 10 et 100 µS/cm par exemple comprise entre 10 et 50 µS/cm. Le rinçage post-colmatage se réalise de préférence à une température comprise entre 10 et 75°C, par exemple comprise entre 15 et 60°C. Le pH de l’eau dans l’étape C) est entre 4,5 et 8,5, de préférence entre 5 et 8, par exemple entre 5,5 et 7,5.
La durée du rinçage post-colmatage est comprise entre 10 secondes et 10 minutes, de préférence comprise entre 10 secondes et 5 minutes, par exemple comprise entre 30 secondes et 2 minutes. Il a été constaté de manière tout à fait inattendue, que l’association des étapes, d’imprégnation + colmatage + rinçage post-colmatage, telles que décrites ci-dessous est indispensable pour garantir de bonnes performances anticorrosion de l’aluminium ou de l’alliage d’aluminium. Des rinçages intermédiaires, notamment à l’eau déminéralisée, peuvent être réalisés entre les étapes décrites ci-dessus. Le colmatage à l’eau bouillante, qui a l’avantage de ne pas utiliser de substances nocives et permet d’améliorer de façon significative la résistance à la corrosion des couches d’anodisation lorsqu’il est bien contrôlé : le colmatage doit s’effectuer dans de l’eau déminéralisée dont la température minimale est supérieure à 75°C, de préférence supérieure à 90°C, plus préférentiellement supérieure ou égale à 96°C et le pH compris entre 5,5 et 6,5. La qualité de l’eau utilisée est importante pour la réussite de l’opération, certaines impuretés étant connues comme néfastes à très faible teneur (par exemple, Ca2+, Cu2+, Fe2+, F-, Cl-, SiO3-, PO43-). On constatera notamment un effet particulièrement nuisible des ions silicates, phosphates et chlorures. La durée de traitement est d'environ 2.5 min/μm (proche de la durée d'anodisation). Cette opération est une thermohydratation partielle de l'alumine qui cristallise en alumine mono- hydratée (Böhmite). Avant de soumettre l’aluminium ou l’alliage d’aluminium à l’étape d’anodisation, l’aluminium ou l’alliage d’aluminium peut être soumis à une étape de préparation de surface par dégraissage et/ou de décapage afin d’éliminer les graisses, salissures et oxydes présents sur sa surface. Cette étape préalable de préparation de surface peut comporter une ou plusieurs des opérations suivantes : - dégraissage au solvant, pour dissoudre des graisses présentes à la surface de l’aluminium ou de l’alliage d’aluminium. Cette opération peut être réalisée par trempage, aspersion, ou tout autre méthode connue de l’homme du métier ; - dégraissage alcalin, pour dissoudre des graisses présentes à la surface de l’aluminium ou de l’alliage d’aluminium. Cette opération peut être réalisée par trempage, aspersion, ou toute autre technique connue de l’homme du métier ;
- décapage alcalin, pour dissoudre les oxydes naturellement formés à la surface de l’aluminium ou de l’alliage d’aluminium. Cette opération peut être réalisée par trempage, aspersion, ou toute autre technique connue de l’homme du métier. A l’issue de cette opération, l’aluminium ou l’alliage d’aluminium est recouvert d’une couche pulvérulente formée de produits d’oxydation des composés intermétalliques, qu’il convient d’éliminer par une étape de décapage acide ; - décapage acide, pour dissoudre les oxydes naturellement formés à la surface de l’aluminium ou de l’alliage d’aluminium, et/ou la couche d’oxydation formée à la surface de la pièce lors de l’étape de décapage alcalin. Cette opération peut être réalisée par trempage, aspersion, ou toute autre technique connue de l’homme du métier. L’étape préalable de préparation de surface de l’aluminium ou de l’alliage d’aluminium par dégraissage et/ou de décapage pour éliminer les graisses, salissures et oxydes présents sur sa surface peut être effectuée dans les conditions décrites, par exemple, dans la demande WO 2013/117759. Des rinçages intermédiaires, notamment à l’eau déminéralisée, sont, de préférence, réalisés entre les étapes successives ci-dessus, et avant le traitement de la pièce par anodisation. Avant l’application du procédé de colmatage de l’invention, l’aluminium ou l’alliage d’aluminium, éventuellement soumis à une étape de préparation de surface par dégraissage et/ou de décapage par une ou plusieurs des opérations décrites ci-dessus, est anodisé. Tout type d’anodisation sur aluminium connu de l’homme du métier peut convenir. A ce titre on peut citer • OAS : Oxydation Anodique Sulfurique (colmatage à base de Chrome VI, procédé impacté par la réglementation européenne REACH), • OAC : Oxydation Anodique Chromique (À base de Chrome VI, procédé impacté par la réglementation européenne REACH), • OAST : Oxydation Anodique SulfoTartrique, • OAST : Oxydation Anodique SulfoTartrique, • OAS NG FE : Oxydation Anodique Sulfurique Nouvelle Génération Fine Epaisseur, • OAS NG : Oxydation Anodique Sulfurique Nouvelle Génération. Dans le cadre de la présente invention, les procédés d’anodisation OAST LC, OAS NG FE, OAS NG sont préférés.
Le procédé de traitement de surface de l’invention améliore sensiblement les propriétés de résistance à la corrosion de pièces en métal ou en alliage métallique, notamment de pièces en aluminium ou en alliage d'aluminium et respectent les exigences de la réglementation européenne REACH. Le procédé de l’invention présente un grand intérêt dans tout type d’industrie où on cherche à améliorer des propriétés de résistance à la corrosion de pièces en métal ou en alliage métallique, notamment de pièces en aluminium ou en alliage d'aluminium, comme dans l’aéronautique, l’automobile, dans l’industrie pétrolière etc. Le procédé selon l’invention peut comprendre une ou plusieurs des caractéristiques et/ou étapes suivantes, prises isolément les unes des autres ou en combinaison les unes avec les autres : - l’alliage d’aluminium est un alliage d’aluminium des séries 2xxx, 6xxx et 7xxx, notamment choisi dans le groupe consistant en 2014, 2017, 2024, 2214, 2219, 2618, AU5NKZr, 7175, 5052, 5086, 6061, 6063, 7010, 7020, 7050, 7050 T7451, 7055, 7068, 7085, 7075, 7175 et 7475, alliages de fonderie d’aluminium type AS7G06, AS7G03, AS10G et AS9U3, alliages d’aluminiums issus de procédés tels que la fabrication d’additive ; - dans l’étape d’imprégnation A), la concentration en sel d’hexafluorozirconate est comprise entre 0,5 et 50 g/L ; - dans l’étape d’imprégnation A), la concentration en sel de manganèse di-, tri, tétra, ou hepta-valent, ou en tungstate est comprise entre 0,1 et 50 g/L ; - le silicate de métal alcalin ou de métal alcalinoterreux est choisi dans le groupe consistant en silicate de lithium, silicate de sodium, silicate de potassium, silicate de calcium et silicate de magnésium ; - la concentration en silicate de métal alcalin ou de métal alcalinoterreux dans la solution est comprise entre 5 et 100 g/L ; - l’étape de rinçage C) se réalise dans une eau déionisée ayant une conductivité comprise entre 1 et 100 µS/cm. Le procédé de l’invention permet d’obtenir une résistance à la corrosion semblable à une anodisation chromaté sans utilisation de chrome. Il permet de trouver une solution de colmatage innovante pour les anodisations des alliages d’aluminium répondant ainsi au cahier des charges de tenue à la corrosion et d’adhérence peinture sans utiliser du chrome.
L’invention concerne également un procédé de traitement de surface d’une pièce en aluminium ou en alliage d’aluminium destinée à être utilisée dans le secteur aéronautique comportant au moins les étapes suivantes : i) soumission de ladite pièce à une étape d’anodisation, ayant éventuellement subie au préalable une étape de préparation de surface (dégraissage, puis décapage) ; ii) traitement de la pièce anodisée par un procédé de colmatage post-anodisation selon l’invention ; et éventuellement iii) application d’une ou de plusieurs couche(s) de peinture. Un autre objet de l’invention est l’utilisation d’un procédé de colmatage post- anodisation selon l’invention, dans le traitement de surface de pièces en aluminium ou en alliage d’aluminium destinées au secteur aéronautique. L’invention a également pour objet, une pièce en aluminium ou en alliage d’aluminium traitée par un procédé de colmatage post-anodisation selon l’invention, comportant éventuellement une ou plusieurs couches(s) de peintures et destinée au secteur aéronautique. Traitement d’anodisation suivi d’une application peinture : certaines pièces aéronautiques ont un traitement de peinture après anodisation afin de renforcer la protection anticorrosion. L’invention est compatible avec des différents systèmes de peinture. D’autres avantages et caractéristiques de l’invention apparaîtront à la lecture des exemples ci-dessous donnés à titre illustratif. EXEMPLES Exemple 1 : Procédé de
anodisation des pièces en alliage d’aluminium Des pièces en alliage d’aluminium 2618 T6 de dimensions 120x100x5 mm sont traitées suivant les méthodes décrites ci-après. Des étapes de préparation de surface de la pièce sont tout d’abord réalisées successivement : - dégraissage alcalin, par trempage de la pièce dans une solution de SOCOCLEAN A3431 à 11% en volume, à une température de 45°C, pendant 10 minutes ; - rinçage à l’eau du robinet ou à l’eau déminéralisée ;
- décapage acide par trempage de la pièce dans un mélange de SOCOSURF A1858 à 42% en volume et SOCOSURF A1806 à 10% en volume à une température de 50°C pendant 10 minutes ; - rinçage à l’eau du robinet ou à l’eau déminéralisée. Les pièces décapées et rincées sont ensuite soumises à un procédé d’anodisation sulfurique nouvelle génération (épaisseur standard ou fine épaisseur (FE)). Les paramètres opératoires pour l’anodisation sont indiqués dans le tableau 1 ci- dessous. [Tableau 1]
Les pièces anodisées selon l’invention sont alors soumises au procédé de colmatage conforme à l’invention dans des conditions et dans l’ordre indiqués ci-dessous dans: - étape A) : une étape imprégnation desdites pièces, successivement, dans un bain aqueux de BONDERITE M-ED 160/161 (15g/L ED160 et 18g/L ED161) à une température de 40°C pendant 10 minutes et à un pH de 3,9, puis - étape B) : un colmatage par immersion des pièces à l’issue une solution aqueuse d’eau déionisée ayant une conductivité inférieure à 100 µS/cm avec 80g/L d’un silicate de sodium, une température de 100°C et pendant 10 minutes ; - étape C) : un rinçage post-colmatage par immersion des pièces à l’issue des trois opérations de colmatages précédentes dans une eau déionisée ayant une conductivité inférieure à 100 µS/cm, à une température de 20°C pendant 1 minutes. Entre chaque étape un rinçage à l’eau déminéralisée est effectué. Ces conditions sont indiquées dans le [Tableau 2]. [Tableau 2]
Résultats de tenue à la corrosion évalués sur les alliages anodisés et colmatés par les méthodes de colmatage conventionnelles et par le procédé de l’invention : A titre de comparaison, les pièces en alliages d’aluminium anodisées selon la méthode indiquée dans le [Tableau 1], sont ensuite soumises à une ou plusieurs opérations de colmatage tels que colmatage hydrothermal (Mn/Zr + Eau) suivant les méthodes connues de l’homme du métier et comparées aux pièces anodisées et colmatées par le procédé de l’invention (Mn/Zr + Silicate). Les pièces ainsi traitées sont soumises à un test de tenue au brouillard salin (BS) conforme à la norme NF EN ISO 9227. Le nombre de piqûres à 500h de brouillard salin (BS) est reporté dans le Tableau 3 ci-dessous. [Tableau 3]
obtiennent, des performances anticorrosion bien meilleures que le colmatage hydrothermal. Au vu de ces résultats, l’impact positif des silicates est détecté et permet d’avoir des résultats intéressants proche d’une imprégnation chromaté. Analyse d’extrême surface (XPS) Des analyses spectrométrique photoélectroniques X (XPS) ont été effectuées sur un instrument THERMO K-alpha+ avec source Al Kalpha monochromatisée Logiciel de traitement : Avantage. La surface d’un échantillon ayant subis une anodisation colmatée au Mn/Zr+Si (nommé 2618-T652-047-104 dans le Tableau 4 ci-dessous). [Tableau 4]
Comme le montre l’analyse élémentaire de l’extrême surface (50 nm de surface), un enrichissement en silicium sous forme oxydée (présence d’oxygène) est détectable. Cela confirme la présence de silicate en surface. La déposition de silicate à la surface d’une anodisation imprégnée au Mn/Zr permet d’améliorer la résistance à la corrosion d’une anodisation sans chrome. L’invention prouve la possibilité de déposer du silicate sur une autre imprégnation que le CrIII/Zr permettant ainsi d’atteindre des performances en corrosion intéressantes sans l’utilisation de chrome.
DESCRIPTION TITLE: PROCESS FOR POST-ANODIZATION SEALING OF ALUMINUM AND ALUMINUM ALLOYS WITHOUT USING CHROME Technical field of the invention The present invention is part of the search for new solutions for anti-corrosion protection of the aluminum or aluminum alloys, particularly for aeronautical applications, with or without application of a paint system. In particular, the process of the invention makes it possible to obtain a coating having very high anti-corrosion properties on aluminum or aluminum alloys, without using chromium. Technical background The technical background includes in particular documents US-A1-2002/117,236, US-A1-2006/191,599, US-B-6,663,700, US-A1-2016/047,057 and WO-A1 - 2013/117767. Aluminum alloys are materials of choice for the transport industry, and more particularly for the aeronautics industry, due to their excellent mechanical properties/weight ratio and their relatively low manufacturing cost. However, these alloys are likely, depending on the environment in which they are found, to be affected by several types of localized corrosion, causing degradation of the part and potentially leading to its removal or failure. Many strategies have been implemented to overcome this weakness, and, among them, the formation or deposition of a protective layer on the surface of alloys is the most used. This is particularly the case for protective layers obtained by the anodizing process for aluminum alloys. Anodizing is an electrolytic process aimed at replacing the natural oxide (native oxide), of a few nanometers which covers the aluminum, with an oxide layer of up to several micrometers. The oxide layers produced by anodization have a thickness that can range from two microns to around fifteen microns, in order to provide protection against long-term corrosion. Anodizing, also called anodic oxidation, therefore consists of forming a layer of porous aluminum oxides/hydroxides called a layer on the surface of the part. anodic, by applying a current to the part immersed in an electrolytic bath containing a strong acid type electrolyte, the part constituting the anode of the electrolytic system. The layer thus formed on the surface of the part, after a sealing treatment, makes it possible to reinforce the corrosion resistance of the part. Anodizing treatments are now commonly used in the aeronautics industry, mainly to improve the corrosion resistance of parts, and therefore their lifespan, but also to facilitate the adhesion of organic layers (paints). However, the anodizing process is directly impacted by European regulations (REACH), which, since September 2017, has prohibited (or restricted to authorization) the use of certain key components in surface treatments, in particular, hexavalent chromium. However, hexavalent chromium is present in the OAC type anodizing treatment (Chromic Anodic Oxidation as described, for example, in www.a3ts.org/actualite/commissions-techniques/fiches-techniques-traitement- surface/anodisation- chromic, but also in the usual surface preparation pretreatments, aimed at cleaning/stripping the surfaces of the parts before the anodizing treatment, and finally in the final so-called sealing treatments, the objective of which is to close the pores of the anodic layer formed during the anodizing treatment. Different processes have therefore been proposed to replace the OAC and OAS (Anodic Sulfuric Oxidation) treatments sealed with hexavalent chromium, impacted by the European REACH regulation: • OAS NG ( new generation sulfuric anodic oxidation as described for example in www.a3ts.org/actualite/commissions-techniques/fiches-techniques-traiture-surface/anodisation-sulfurique-version-5-2) has been proposed to replace OAS; • OAST (anodic sulfo-tartaric oxidation as described, for example, in www.a3ts.org/actualite/commissions-techniques/fiches-techniques-traiteur-surface/anodisation-sulfo-tartrique-oast-tartric-sulfuric- anodizing-tsa was proposed to replace OAC. OAC can also be replaced by OAS NG FE (new generation thin thickness sulfuric anodic oxidation) which is an OAS NG type anodizing whose anodizing parameters (Voltage , Immersion time) were adapted to obtain an anodizing layer whose thickness is between 2 and 7 µm. Although current classic anodizing solutions, such as for example OAS NG followed by hot water sealing, implement treatment ranges compatible with the European REACH regulations, they nevertheless remain little or not satisfactory in terms of anti-corrosion protection on certain grades of so-called “difficult” aluminum alloys. As a non-limiting example of so-called “difficult” aluminum alloys, we can cite alloys 2214, 2618A or AU5NKZr. These alloys have particular microstructures due to their chemical composition, which give them either foundry-type defects or precipitates such as intermetallics rich in copper or iron or nickel, etc. Thus, when the anodic layer forms on the surface of these alloys, layer defects can reside, leading to certain local fragilities susceptible to corrosion. For these alloys, it is therefore necessary to optimize the anodizing ranges in order to improve anti-corrosion performance. FR 3106838B1 offers a post-anodization sealing process for aluminum or aluminum alloy which makes it possible to improve the corrosion resistance of the part without using hexavalent chromium impacted by European REACH regulations. This process, which is also suitable for so-called “difficult” aluminum alloys, comprises a step of impregnating the aluminum or the aluminum alloy in an aqueous bath containing a hexaflurozirconate salt and a trivalent chromium salt followed by a sealing step carried out in an aqueous solution comprising an alkali metal or alkaline earth metal silicate. Despite the improvement in anti-corrosion performance provided by this process, there is a risk of long-term obsolescence of trivalent Cr. Indeed, the Cr III /Zr impregnation step which is obligatory to allow the silicate sealing step to take place, may be subject to obsolescence (because of chromium) in the future with the tightening of environmental regulations. . To prevent the long-term obsolescence of trivalent Cr and to be able to comply with future tightening of environmental regulations, it is necessary to optimize the sealing process for anodized aluminum or aluminum alloys, in particular by avoiding the use chromium. There is therefore a real need for a process for sealing aluminum or aluminum alloys, including so-called “difficult” anodized aluminum alloys, which do not use chromium. In particular, there is a real need for a post-anodization sealing process as described above, which provides good anti-corrosion performance for aluminum or aluminum alloy including so-called aluminum alloys. “difficult”, while complying with the requirements of current and future REACH regulations. Summary of the invention The present invention aims precisely to meet these needs, in particular, in terms of corrosion resistance of aluminum alloys, in particular of the 2xxx, 6xxx and 7xxx series, of aluminum foundry alloys. such as AS7G06, AS7G03, AS10G or AS9U3, aluminum alloys from processes such as additive manufacturing, and so-called difficult aluminum alloys, by providing a post-anodization sealing process for aluminum or aluminum alloy, comprising at least the following steps: A) a step of impregnating the aluminum or the anodized aluminum alloy, in an aqueous bath of demineralized water containing • a hexafluorozirconate salt chosen from the group consisting of ammonium hexafluorozirconate ((NH4)2ZrF6), sodium hexafluorozirconate (Na 2 ZrF 6 ), potassium hexafluorozirconate (K 2 ZrF 6 ), and • a di-, tri, tetra, or manganese salt hepta-valent selected from the group consisting of lithium permanganate (LiMnO4), sodium permanganate (NaMnO4), potassium permanganate (KMnO 4 ), ammonium permanganate (NH 4 MnO 4 ), manganese chloride (MnCl2(H2O) x, where the value of K2ZrF6), and • a tungsten salt selected from the group consisting of lithium tungstate (Li2WO4), sodium tungstate (Na2WO4), potassium tungstate (K2WO4), calcium tungstate (CaWO4), zirconium tungstate (Zr(WO4 )2), ammonium tungstate potassium tungstate ((NH 4 ) 10 H 2 (W 2 O 7 ) 6 ), at a temperature between 20 and 80°C; B) a sealing step carried out in an aqueous solution of deionized water having a conductivity less than or equal to 100 µS/cm containing between 1 and 500 g/L of a silicate of alkali metal or alkaline earth metal, at a temperature between 60 and 100°C; C) a post-clogging rinsing step in deionized water having a conductivity less than or equal to 100 µS/cm and at a temperature between 15 and 75°C. In impregnation step A), the hexafluorozirconate salt concentration is between 0.5 and 50 g/L. The concentration of manganese salt in this step is between 0.1 and 50 g/L. Intermediate rinses, in particular with demineralized water, are preferably carried out - between steps A) and B), and/or - before and/or after the treatment of the part by anodization. As the anodizing layers have a very porous structure, when chemical and/or corrosion resistance is essential, the anodizing layer must be sealed. This implies that the aluminum oxide layer is transformed into an aluminum hydroxide complex where the pores are sealed. Consequently, sealing, in addition to anodizing, is decisive for the quality of the anodizing layer because: • sealing the pores leads to an increase in corrosion resistance; • clogging is avoided; • leaching of dyes out of the pores is avoided. The post-anodization sealing process of the invention makes it possible to obtain a coating having very high anti-corrosion properties on so-called difficult aluminum alloys such as, for example, 2618A and 2214, but also on the most difficult aluminum alloys. more common in the aeronautical field, such as the 2024 or the 7175 for example. The sealing process of the invention can be applied to different anodizations known to those skilled in the art, among which we can cite OAST, OAS NG FE, OAS NG. It may or may not be followed by an application of paint. The process of the invention demonstrates the possibility of using other types of chrome-free impregnation layers making it possible to deposit the silicate on the surface, such as for example a Mn/Zr impregnation. Knowing that a sulfuric anodization is composed of a layer of aluminum oxide, the inventors sought to know a) if it was possible to deposit silicate on a chrome-free impregnation layer, for example a layer of 'Mn/Zr impregnation instead of Cr III /Zr, and b) if yes, if this deposition would improve the corrosion resistance of the chrome-free impregnation layer, for example a Mn/Zr impregnation layer, as is the case for a Cr III /Zr impregnation layer. The invention also relates to a method for surface treatment of a part made of aluminum or aluminum alloy intended to be used in the aeronautics sector comprising at least the following steps: i) subjecting said part to an anodizing step , possibly having previously undergone a surface preparation step (degreasing, then stripping); ii) treatment of the anodized part by a post-anodization sealing process according to the invention; and possibly iii) application of one or more coat(s) of paint. Another object of the invention is the use of a post-anodization sealing process according to the invention, in the surface treatment of aluminum or aluminum alloy parts intended for the aeronautical sector. The invention also relates to a part made of aluminum or aluminum alloy treated by a post-anodization sealing process according to the invention, possibly comprising one or more layers of paint and intended for the aeronautical sector. Brief description of the figures Other characteristics and advantages of the invention will appear during reading of the detailed description which follows for the understanding of which we will refer to the appended drawings in which: [Fig.1] Figure 1 represents a theoretical diagram comparing the deposition of species on the anodization layer (OA) by the sealing process described in FR3106838B1 and by the sealing process of the invention. Detailed description of the invention The present invention aims precisely to meet the needs of the state of the art, in particular, in terms of corrosion resistance of aluminum alloys, in particular of the 2xxx, 6xxx and 7xxx series, of foundry alloys, and aluminum alloys from processes such as additive manufacturing and so-called difficult aluminum alloys, by providing a process for post-anodization sealing of aluminum or aluminum alloy, comprising at least the following steps: A) a step of impregnating the aluminum or the anodized aluminum alloy, in an aqueous bath of demineralized water containing • a hexafluorozirconate salt chosen from the group consisting of ammonium hexafluorozirconate ((NH 4 ) 2 ZrF 6 ), sodium hexafluorozirconate (Na 2 ZrF 6 ), potassium hexafluorozirconate (K 2 ZrF 6 ), and • a di-, tri-, tetra-, or hepta-valent manganese salt chosen from the group consisting of permanganate lithium (LiMnO 4 ), sodium permanganate (NaMnO 4 ), potassium permanganate (KMnO4), ammonium permanganate (NH4MnO4), manganese chloride (MnCl2(H2O)x, where the value of x is 0, 2 or 4), or • a hexafluorozirconate salt chosen from the group consisting of ammonium hexafluorozirconate ((NH4)2ZrF6), sodium hexafluorozirconate (Na 2 ZrF 6 ), potassium hexafluorozirconate (K 2 ZrF 6 ), and • a tungsten salt selected from the group consisting of lithium tungstate (Li2WO4), sodium tungstate (Na2WO4), potassium tungstate (K2WO4), calcium tungstate (CaWO 4) , zirconium tungstate (Zr(WO 4 ) 2 ), ammonium tungstate potassium tungstate ((NH 4 ) 10 H 2 (W 2 O 7 ) 6 ), at a temperature between 20 and 80°C; B) a sealing step carried out in an aqueous solution of deionized water having a conductivity less than or equal to 100 µS/cm containing between 1 and 500 g/L of an alkali metal or alkaline earth metal silicate, at a temperature between between 60 and 100°C; C) a post-clogging rinsing step in deionized water having a conductivity less than or equal to 100 µS/cm and at a temperature between 15 and 75°C. The di-, tri-, tetra-, or hepta-valent manganese salt may be, for example, one of the following commercial products: Bonderite M-ED160/161. The tungstate salt may be, for example, one of the following commercial products: lithium tungstate (Li2WO4), sodium tungstate (Na2WO4), potassium tungstate (K 2 WO 4 ), calcium tungstate (CaWO 4) , ammonium tungstate tungstate potassium ((NH 4 ) 10 H 2 (W 2 O 7 ) 6 ) from the Sigma Aldrich brand from the company Merck, and zirconium tungstate (Zr(WO4)2) from the company Fisher Scientific. Intermediate rinses, in particular with demineralized water, are preferably carried out - between steps A) and B), and/or - before and/or after the treatment of the part by anodization. The optimized sealing process of the invention can be suitable for any type of aluminum alloys including so-called “difficult” alloys, in particular aluminum alloys of the 2xxx, 6xxx and 7xxx series, previously anodized by different processes, for example for example, by the OAST (sulfo-tartaric anodic oxidation), OAS NG FE (new generation thin thickness anodic sulfuric oxidation) or OAS NG (new generation sulfuric anodic oxidation) processes. Furthermore, the post-anodization sealing process of the invention is compatible with the requirements associated with the European REACH regulation and leads to good anti-corrosion protection on so-called “difficult” aluminum alloys (for example, 2618A, 2214 and AU5NKZr). This process may or may not be followed by an application of paint. Thus, the post-anodization sealing process of the invention makes it possible to obtain a coating having very high anti-corrosion properties on aluminum alloys of the 2xxx, 6xxx and 7xxx series and difficult aluminum alloys, but also on most common aluminum alloys in the aeronautical field, such as 2024 and 7175 and so-called “difficult” aluminum alloys such as 2618A and 2214. The process of the invention is suitable, more particularly, for aluminum and aluminum alloy parts of the 2xxx, 6xxx and 7xxx series, in particular selected from the group consisting of 2014, 2017, 2024, 2214, 2219, 2618, AU5NKZr, 7175, 5052, 5086, 6061, 6063, 7010, 7020 , 7050, 7050 T7451, 7055, 7068, 7085, 7075, 7175 and 7475, aluminum foundry alloys type AS7G06, AS7G03, AS10G and AS9U3, aluminum alloys from processes such as additive manufacturing. In the impregnation step A), the concentration of hexafluorozirconate salt is between 0.5 and 50 g/L, for example equal to 2 g/L. The concentration of di-, tri-, tetra-, or hepta-valent manganese salt, or tungstate salt in this step is between 0.1 and 50 g/L, for example equal to 1 g/L. The temperature of the bath in step A) can be between 20 and 80°C, preferably between 20 and 60°C, more preferably between 35 and 60°C, for example between 35 and 45°C. The pH of the bath in step A) is between 3 and 5, preferably between 3.5 and 4.5, for example between 3.7 and 4.2. The duration of the impregnation in the bath in step A) is between 1 and 40 minutes, preferably between 5 and 30 minutes, for example between 5 and 20 minutes. The impregnation step A) is followed by a step B) which is a sealing step. The clogging of step B) is carried out in an aqueous solution of deionized water having a conductivity less than or equal to 200 µS/cm, preferably between 1 and 100 µS/cm, for example between 1 and 50 µS/ cm. The temperature of the aqueous solution of step B) is preferably between 80 and 100°C, for example between 80 and 98°C. The alkali metal or alkaline earth metal silicate may be selected from the group consisting of lithium silicate, sodium silicate, potassium silicate, calcium silicate and magnesium silicate. In the clogging step B), the concentration of alkali metal or alkaline earth metal silicate in the solution is preferably between 1 and 500 g/L, for example between 5 and 100 g/L. The duration of the clogging step B) is between 1 and 40 minutes, preferably between 5 and 35 minutes, for example between 5 and 30 minutes. The pH of the sealing solution is between 9 and 12, preferably between 10 and 11.5 minutes, for example between 10.5 and 11.4. The clogging is followed by a rinsing step C) in deionized water having a conductivity less than or equal to 100 µS/cm, preferably between 1 and 100 µS/cm, more preferably between 10 and 100 µS/cm per example between 10 and 50 µS/cm. Post-clogging rinsing is preferably carried out at a temperature between 10 and 75°C, for example between 15 and 60°C. The pH of the water in step C) is between 4.5 and 8.5, preferably between 5 and 8, for example between 5.5 and 7.5. The duration of the post-clogging rinse is between 10 seconds and 10 minutes, preferably between 10 seconds and 5 minutes, for example between 30 seconds and 2 minutes. It was found, quite unexpectedly, that the combination of the steps, impregnation + clogging + post-clogging rinsing, as described below is essential to guarantee good anti-corrosion performance of aluminum or metal. 'aluminum alloy. Intermediate rinses, in particular with demineralized water, can be carried out between the steps described above. Sealing with boiling water, which has the advantage of not using harmful substances and makes it possible to significantly improve the corrosion resistance of the anodizing layers when it is well controlled: the sealing must be carry out in demineralized water whose minimum temperature is greater than 75°C, preferably greater than 90°C, more preferably greater than or equal to 96°C and the pH between 5.5 and 6.5. The quality of the water used is important for the success of the operation, with certain impurities being known to be harmful at very low levels (for example, Ca 2+ , Cu 2+ , Fe 2+ , F-, Cl-, SiO3 -, PO4 3- ). In particular, we will note a particularly harmful effect of silicate, phosphate and chloride ions. The treatment time is approximately 2.5 min/μm (close to the anodizing time). This operation is a partial thermohydration of the alumina which crystallizes into monohydrated alumina (Böhmite). Before subjecting the aluminum or aluminum alloy to the anodizing step, the aluminum or aluminum alloy may be subjected to a surface preparation step by degreasing and/or pickling in order to remove grease, dirt and oxides present on its surface. This preliminary surface preparation step may include one or more of the following operations: - solvent degreasing, to dissolve grease present on the surface of the aluminum or aluminum alloy. This operation can be carried out by soaking, sprinkling, or any other method known to those skilled in the art; - alkaline degreasing, to dissolve grease present on the surface of aluminum or aluminum alloy. This operation can be carried out by soaking, sprinkling, or any other technique known to those skilled in the art; - alkaline stripping, to dissolve the oxides naturally formed on the surface of aluminum or aluminum alloy. This operation can be carried out by soaking, sprinkling, or any other technique known to those skilled in the art. At the end of this operation, the aluminum or aluminum alloy is covered with a powdery layer formed of oxidation products of the intermetallic compounds, which must be eliminated by an acid pickling step; - acid pickling, to dissolve the oxides naturally formed on the surface of the aluminum or aluminum alloy, and/or the oxidation layer formed on the surface of the part during the alkaline pickling step. This operation can be carried out by soaking, sprinkling, or any other technique known to those skilled in the art. The preliminary step of surface preparation of the aluminum or aluminum alloy by degreasing and/or pickling to eliminate grease, dirt and oxides present on its surface can be carried out under the conditions described, for example, in application WO 2013/117759. Intermediate rinses, in particular with demineralized water, are preferably carried out between the successive stages above, and before treatment of the part by anodization. Before applying the sealing process of the invention, the aluminum or aluminum alloy, optionally subjected to a surface preparation step by degreasing and/or pickling by one or more of the operations described above , is anodized. Any type of anodizing on aluminum known to those skilled in the art may be suitable. In this respect we can cite • OAS: Anodic Sulfuric Oxidation (clogging based on Chromium VI, process impacted by European REACH regulations), • OAC: Chromic Anodic Oxidation (Based on Chromium VI, process impacted by European REACH regulations) , • OAST: SulfoTartaric Anodic Oxidation, • OAST: SulfoTartaric Anodic Oxidation, • OAS NG FE: New Generation Sulfuric Anodic Oxidation Fine Thickness, • OAS NG: New Generation Sulfuric Anodic Oxidation. In the context of the present invention, the OAST LC, OAS NG FE, OAS NG anodizing processes are preferred. The surface treatment process of the invention significantly improves the corrosion resistance properties of metal or metal alloy parts, in particular aluminum or aluminum alloy parts and complies with the requirements of the European REACH regulations. The process of the invention is of great interest in any type of industry where one seeks to improve the corrosion resistance properties of parts made of metal or a metal alloy, in particular parts made of aluminum or an aluminum alloy, such as in aeronautics, automobiles, the oil industry, etc. The method according to the invention may comprise one or more of the following characteristics and/or steps, taken in isolation from each other or in combination with each other: - the aluminum alloy is an aluminum alloy of the 2xxx series , 6xxx and 7xxx, in particular chosen from the group consisting of 2014, 2017, 2024, 2214, 2219, 2618, AU5NKZr, 7175, 5052, 5086, 6061, 6063, 7010, 7020, 7050, 7050 T7451, 7055, 7068, 7085 , 7075, 7175 and 7475, aluminum foundry alloys type AS7G06, AS7G03, AS10G and AS9U3, aluminum alloys from processes such as additive manufacturing; - in impregnation step A), the hexafluorozirconate salt concentration is between 0.5 and 50 g/L; - in the impregnation step A), the concentration of di-, tri-, tetra-, or hepta-valent manganese salt, or tungstate is between 0.1 and 50 g/L; - the alkali metal or alkaline earth metal silicate is chosen from the group consisting of lithium silicate, sodium silicate, potassium silicate, calcium silicate and magnesium silicate; - the concentration of alkali metal or alkaline earth metal silicate in the solution is between 5 and 100 g/L; - rinsing step C) is carried out in deionized water having a conductivity between 1 and 100 µS/cm. The process of the invention makes it possible to obtain corrosion resistance similar to chromated anodizing without the use of chrome. It makes it possible to find an innovative sealing solution for the anodization of aluminum alloys, thus meeting the specifications for corrosion resistance and paint adhesion without using chrome. The invention also relates to a method for surface treatment of a part made of aluminum or aluminum alloy intended to be used in the aeronautics sector comprising at least the following steps: i) subjecting said part to an anodizing step , possibly having previously undergone a surface preparation step (degreasing, then stripping); ii) treatment of the anodized part by a post-anodization sealing process according to the invention; and possibly iii) application of one or more coat(s) of paint. Another object of the invention is the use of a post-anodization sealing process according to the invention, in the surface treatment of aluminum or aluminum alloy parts intended for the aeronautical sector. The invention also relates to a part made of aluminum or aluminum alloy treated by a post-anodization sealing process according to the invention, possibly comprising one or more layers of paint and intended for the aeronautical sector. Anodizing treatment followed by a paint application: certain aeronautical parts have a paint treatment after anodizing in order to reinforce anti-corrosion protection. The invention is compatible with different painting systems. Other advantages and characteristics of the invention will appear on reading the examples below given for illustration. EXAMPLES Example 1: Method of anodizing of aluminum alloy parts Parts of 2618 T6 aluminum alloy with dimensions 120x100x5 mm are treated according to the methods described below. Surface preparation steps for the part are first carried out successively: - alkaline degreasing, by soaking the part in a solution of SOCOCLEAN A3431 at 11% by volume, at a temperature of 45°C, for 10 minutes; - rinsing with tap water or demineralized water; - acid stripping by soaking the part in a mixture of SOCOSURF A1858 at 42% by volume and SOCOSURF A1806 at 10% by volume at a temperature of 50°C for 10 minutes; - rinsing with tap water or demineralized water. The stripped and rinsed parts are then subjected to a new generation sulfuric anodizing process (standard thickness or fine thickness (FE)). The operating parameters for anodizing are indicated in table 1 below. [Table 1] The anodized parts according to the invention are then subjected to the sealing process in accordance with the invention under the conditions and in the order indicated below in: - step A): a step of impregnation of said parts, successively, in an aqueous bath of BONDERITE M-ED 160/161 (15g/L ED160 and 18g/L ED161) at a temperature of 40°C for 10 minutes and at a pH of 3.9, then - step B): sealing by immersion of the parts at the end an aqueous solution of deionized water having a conductivity less than 100 µS/cm with 80g/L of a sodium silicate, a temperature of 100°C and for 10 minutes; - step C): post-clogging rinsing by immersing the parts after the three previous clogging operations in deionized water having a conductivity less than 100 µS/cm, at a temperature of 20°C for 1 minute. Between each step, rinsing with demineralized water is carried out. These conditions are shown in [Table 2]. [Table 2] Corrosion resistance results evaluated on anodized and sealed alloys by conventional sealing methods and by the process of the invention: For comparison, the aluminum alloy parts anodized according to the method indicated in [Table 1 ], are then subjected to one or more sealing operations such as hydrothermal sealing (Mn/Zr + Water) according to methods known to those skilled in the art and compared to the anodized and sealed parts by the process of the invention (Mn/ Zr + Silicate). The parts thus treated are subjected to a salt spray (BS) resistance test in accordance with standard NF EN ISO 9227. The number of pitting at 500 hours of salt spray (BS) is reported in Table 3 below. [Table 3] obtain much better anti-corrosion performance than hydrothermal sealing. In view of these results, the positive impact of silicates is detected and allows for interesting results close to chromated impregnation. Extreme surface analysis (XPS) X-ray photoelectron spectrometric analyzes (XPS) were carried out on a THERMO K-alpha+ instrument with a monochromatized Al Kalpha source Processing software: Advantage. The surface of a sample having undergone an anodization sealed with Mn/Zr+Si (named 2618-T652-047-104 in Table 4 below). [Table 4] As shown by the elemental analysis of the extreme surface (50 nm surface), an enrichment of silicon in oxidized form (presence of oxygen) is detectable. This confirms the presence of silicate on the surface. The deposition of silicate on the surface of an anodization impregnated with Mn/Zr makes it possible to improve the corrosion resistance of a chrome-free anodization. The invention proves the possibility of depositing silicate on an impregnation other than Cr III /Zr, thus making it possible to achieve interesting corrosion performances without the use of chromium.
Claims
REVENDICATIONS 1. Procédé de colmatage post-anodisation de l’aluminium ou de l’alliage d'aluminium, comportant au moins les étapes suivantes : A) une étape d’imprégnation de l’aluminium ou de l’alliage d'aluminium anodisé, dans un bain aqueux d’eau déminéralisée contenant • un sel d’hexafluorozirconate choisi dans le groupe consistant en hexafluorozirconate d’ammonium ((NH4)2ZrF6), hexafluorozirconate de sodium (Na2ZrF6), hexafluorozirconate de potassium (K2ZrF6), et • un sel de manganèse di-, tri, tétra, ou hepta-valent choisi dans le groupe consistant en permanganate de lithium (LiMnO4), permanganate de sodium (NaMnO4), permanganate de potassium (KMnO4), permanganate d’ammonium (NH4MnO4), chlorure de manganèse (MnCl2(H2O)x, où la valeur de x est 0, 2 ou 4, ou • un sel d’hexafluorozirconate choisi dans le groupe consistant en hexafluorozirconate d’ammonium ((NH4)2ZrF6), hexafluorozirconate de sodium (Na2ZrF6), hexafluorozirconate de potassium (K2ZrF6), et • un sel de tungstène choisi dans le groupe consistant en tungstate de lithium (Li2WO4), tungstate de sodium (Na2WO4), tungstate de potassium (K2WO4), tungstate de calcium (CaWO4), tungstate de zirconium (Zr(WO4)2), tungstate d’ammonium tungstate de potassium ((NH4)10H2(W2O7)6), à une température comprise entre 20 et 80°C ; B) une étape de colmatage réalisée dans une solution aqueuse d’eau déionisée ayant une conductivité inférieure ou égale à 100 µS/cm contenant entre 1 et 500 g/L d’un silicate de métal alcalin ou de métal alcalinoterreux, à une température comprise entre 60 et 100°C ; C) une étape de rinçage post-colmatage dans une eau déionisée ayant une conductivité inférieure ou égale à 100 µS/cm et à une température comprise entre 15 et 75°C. CLAIMS 1. Process for post-anodization sealing of aluminum or aluminum alloy, comprising at least the following steps: A) a step of impregnating the anodized aluminum or aluminum alloy, in an aqueous bath of demineralized water containing • a hexafluorozirconate salt chosen from the group consisting of ammonium hexafluorozirconate ((NH 4 ) 2 ZrF 6 ), sodium hexafluorozirconate (Na2ZrF6), potassium hexafluorozirconate (K2ZrF6), and • a di-, tri-, tetra-, or hepta-valent manganese salt chosen from the group consisting of lithium permanganate (LiMnO4), sodium permanganate (NaMnO4), potassium permanganate (KMnO4), ammonium permanganate (NH4MnO4) , manganese chloride (MnCl 2 (H 2 O) x , where the value of x is 0, 2 or 4, or • a hexafluorozirconate salt selected from the group consisting of ammonium hexafluorozirconate ((NH 4 ) 2 ZrF 6 ), sodium hexafluorozirconate (Na 2 ZrF 6 ), potassium hexafluorozirconate (K 2 ZrF 6 ), and • a tungsten salt selected from the group consisting of lithium tungstate (Li 2 WO 4 ), sodium tungstate (Na 2 WO 4 ), potassium tungstate (K 2 WO 4 ), calcium tungstate (CaWO 4) , zirconium tungstate (Zr(WO 4 ) 2 ), ammonium tungstate potassium tungstate ((NH4)10H2(W2O7) 6), at a temperature between 20 and 80°C; B) a sealing step carried out in an aqueous solution of deionized water having a conductivity less than or equal to 100 µS/cm containing between 1 and 500 g/L of an alkali metal or alkaline earth metal silicate, at a temperature between between 60 and 100°C; C) a post-clogging rinsing step in deionized water having a conductivity less than or equal to 100 µS/cm and at a temperature between 15 and 75°C.
2. Procédé selon la revendication 1, caractérisé en ce que l’alliage d’aluminium est un alliage d’aluminium des séries 2xxx, 6xxx et 7xxx, notamment choisi dans le groupe consistant en 2014, 2017, 2024, 2214, 2219, 2618, AU5NKZr, 7175, 5052, 5086, 6061, 6063, 7010, 7020, 7050, 7050 T7451, 7055, 7068, 7085, 7075, 7175 et 7475, alliages
de fonderie d’aluminium type AS7G06, AS7G03, AS10G et AS9U3, alliages d’aluminiums issus de procédés tels que la fabrication d’additive2. Method according to claim 1, characterized in that the aluminum alloy is an aluminum alloy of the 2xxx, 6xxx and 7xxx series, in particular chosen from the group consisting of 2014, 2017, 2024, 2214, 2219, 2618 , AU5NKZr, 7175, 5052, 5086, 6061, 6063, 7010, 7020, 7050, 7050 T7451, 7055, 7068, 7085, 7075, 7175 and 7475, alloys aluminum foundry type AS7G06, AS7G03, AS10G and AS9U3, aluminum alloys from processes such as additive manufacturing
3. Procédé selon l’une des revendications 1 ou 2, caractérisé en ce que dans l’étape d’imprégnation A), la concentration en sel d’hexafluorozirconate est comprise entre 0,5 et 50 g/L. 3. Method according to one of claims 1 or 2, characterized in that in the impregnation step A), the concentration of hexafluorozirconate salt is between 0.5 and 50 g/L.
4. Procédé selon l’une quelconque des revendications 1 à 3, caractérisé en ce que dans l’étape d’imprégnation A), la concentration en sel de manganèse di-, tri, tétra, ou hepta-valent, ou en sel de tungstate est comprise entre 0,1 et 50 g/L. 4. Method according to any one of claims 1 to 3, characterized in that in the impregnation step A), the concentration of di-, tri, tetra, or hepta-valent manganese salt, or of manganese salt tungstate is between 0.1 and 50 g/L.
5. Procédé selon l’une quelconque des revendications 1 à 4, caractérisé en ce que le colmatage de l’étape B) est réalisé dans une solution aqueuse d’eau déionisée ayant une conductivité comprise entre 1 et 100 µS/cm. 5. Method according to any one of claims 1 to 4, characterized in that the clogging of step B) is carried out in an aqueous solution of deionized water having a conductivity between 1 and 100 µS/cm.
6. Procédé selon l’une quelconque des revendications 1 à 5, caractérisé en ce que le silicate de métal alcalin ou de métal alcalinoterreux est choisi dans le groupe consistant en silicate de lithium, silicate de sodium, silicate de potassium, silicate de calcium et silicate de magnésium. 6. Method according to any one of claims 1 to 5, characterized in that the alkali metal or alkaline earth metal silicate is chosen from the group consisting of lithium silicate, sodium silicate, potassium silicate, calcium silicate and magnesium silicate.
7. Procédé selon l’une quelconque des revendications 1 à 6, caractérisé en ce que la concentration en silicate de métal alcalin ou de métal alcalinoterreux dans la solution est comprise entre 5 et 100 g/L. 7. Method according to any one of claims 1 to 6, characterized in that the concentration of alkali metal or alkaline earth metal silicate in the solution is between 5 and 100 g/L.
8. Procédé selon l’une quelconque des revendications 1 à 7, caractérisé en ce que l’étape de rinçage C) se réalise dans une eau déionisée ayant une conductivité comprise entre 1 et 100 µS/cm. 8. Method according to any one of claims 1 to 7, characterized in that the rinsing step C) is carried out in deionized water having a conductivity between 1 and 100 µS/cm.
9. Procédé de traitement de surface d’une pièce en aluminium ou en alliage d’aluminium destinée à être utilisée dans le secteur aéronautique comportant au moins les étapes suivantes : i) soumission de ladite pièce à une étape d’anodisation, ayant éventuellement subie au préalable une étape de préparation de surface (dégraissage, puis décapage) ; ii) traitement de la pièce anodisée par un procédé de colmatage post-anodisation selon l’une quelconque des revendications 1 à 8 ; et éventuellement iii) application d’une ou de plusieurs couche(s) de peinture. 9. Process for surface treatment of a part made of aluminum or aluminum alloy intended to be used in the aeronautics sector comprising at least the following steps: i) subjecting said part to an anodizing step, possibly having undergone first a surface preparation step (degreasing, then stripping); ii) treatment of the anodized part by a post-anodization sealing process according to any one of claims 1 to 8; and possibly iii) application of one or more coat(s) of paint.
10. Utilisation d’un procédé de colmatage post-anodisation selon l’une quelconque des revendications 1 à 8, dans le traitement de surface de pièces en aluminium ou en alliage d’aluminium destinées au secteur aéronautique.
10. Use of a post-anodization sealing process according to any one of claims 1 to 8, in the surface treatment of aluminum or aluminum alloy parts intended for the aeronautical sector.
11. Pièce en aluminium ou en alliage d’aluminium traitée par un procédé de colmatage post-anodisation selon l’une quelconque des revendications 1 à 8, comportant éventuellement une ou plusieurs couches(s) de peinture, destinée au secteur aéronautique.
11. Aluminum or aluminum alloy part treated by a post-anodization sealing process according to any one of claims 1 to 8, possibly comprising one or more layers of paint, intended for the aeronautical sector.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FRFR2210150 | 2022-10-04 | ||
| FR2210150A FR3140382A1 (en) | 2022-10-04 | 2022-10-04 | PROCESS FOR POST-ANODIZATION SEALING OF ALUMINUM AND ALUMINUM ALLOYS WITHOUT USING CHROME |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO2024074774A1 true WO2024074774A1 (en) | 2024-04-11 |
Family
ID=85176054
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/FR2023/051483 WO2024074774A1 (en) | 2022-10-04 | 2023-09-27 | Method for post-anodisation sealing of aluminium and aluminium alloys without using chromium |
Country Status (2)
| Country | Link |
|---|---|
| FR (1) | FR3140382A1 (en) |
| WO (1) | WO2024074774A1 (en) |
Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20020117236A1 (en) | 2000-10-31 | 2002-08-29 | Matzdorf Craig A. | Post-treatment for anodized aluminum |
| US6663700B1 (en) | 2000-10-31 | 2003-12-16 | The United States Of America As Represented By The Secretary Of The Navy | Post-treatment for metal coated substrates |
| US20060191599A1 (en) | 2005-02-15 | 2006-08-31 | The U.S. Of America As Represented By The Secretary Of The Navy | Process for sealing phosphoric acid anodized aluminums |
| WO2013117767A1 (en) | 2012-02-10 | 2013-08-15 | Mecaprotec Industries | Method for the surface treatment of parts made of an aluminum or magnesium alloy |
| WO2013117759A1 (en) | 2012-02-10 | 2013-08-15 | Mecaprotec Industries | Method for anodizing parts made of an aluminum alloy |
| US20180202061A1 (en) * | 2017-01-13 | 2018-07-19 | Macdermid Acumen, Inc. | Sealing Anodized Aluminum Using a Low-Temperature Nickel-Free Process |
| WO2019239077A1 (en) * | 2018-06-14 | 2019-12-19 | Liebherr-Aerospace Toulouse Sas | Process for treating the surface of a part made of aluminium or aluminium alloy or of magnesium or magnesium alloy |
| FR3087208A1 (en) * | 2018-10-16 | 2020-04-17 | Irt Antoine De Saint Exupery | PROCESS FOR THE SURFACE TREATMENT OF ALUMINUM PARTS |
| WO2021152240A1 (en) * | 2020-01-31 | 2021-08-05 | Safran Aerosystems | Method for the surface treatment of aluminium-based parts |
| FR3106838B1 (en) | 2020-01-31 | 2022-01-14 | Safran Aircraft Engines | ALUMINUM ALLOY CLOGGING PROCESS |
-
2022
- 2022-10-04 FR FR2210150A patent/FR3140382A1/en active Pending
-
2023
- 2023-09-27 WO PCT/FR2023/051483 patent/WO2024074774A1/en unknown
Patent Citations (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20020117236A1 (en) | 2000-10-31 | 2002-08-29 | Matzdorf Craig A. | Post-treatment for anodized aluminum |
| US6663700B1 (en) | 2000-10-31 | 2003-12-16 | The United States Of America As Represented By The Secretary Of The Navy | Post-treatment for metal coated substrates |
| US20060191599A1 (en) | 2005-02-15 | 2006-08-31 | The U.S. Of America As Represented By The Secretary Of The Navy | Process for sealing phosphoric acid anodized aluminums |
| WO2013117767A1 (en) | 2012-02-10 | 2013-08-15 | Mecaprotec Industries | Method for the surface treatment of parts made of an aluminum or magnesium alloy |
| WO2013117759A1 (en) | 2012-02-10 | 2013-08-15 | Mecaprotec Industries | Method for anodizing parts made of an aluminum alloy |
| US20160047057A1 (en) | 2012-02-10 | 2016-02-18 | Mecaprotec Industries | Method for anodizing parts made of an aluminum alloy |
| US20180202061A1 (en) * | 2017-01-13 | 2018-07-19 | Macdermid Acumen, Inc. | Sealing Anodized Aluminum Using a Low-Temperature Nickel-Free Process |
| WO2019239077A1 (en) * | 2018-06-14 | 2019-12-19 | Liebherr-Aerospace Toulouse Sas | Process for treating the surface of a part made of aluminium or aluminium alloy or of magnesium or magnesium alloy |
| FR3087208A1 (en) * | 2018-10-16 | 2020-04-17 | Irt Antoine De Saint Exupery | PROCESS FOR THE SURFACE TREATMENT OF ALUMINUM PARTS |
| WO2021152240A1 (en) * | 2020-01-31 | 2021-08-05 | Safran Aerosystems | Method for the surface treatment of aluminium-based parts |
| FR3106837A1 (en) * | 2020-01-31 | 2021-08-06 | Safran Aerosystems | SURFACE TREATMENT PROCESS OF ALUMINUM-BASED PARTS |
| FR3106838B1 (en) | 2020-01-31 | 2022-01-14 | Safran Aircraft Engines | ALUMINUM ALLOY CLOGGING PROCESS |
Also Published As
| Publication number | Publication date |
|---|---|
| FR3140382A1 (en) | 2024-04-05 |
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