EP3810833A1 - Process for treating the surface of a part made of aluminium or aluminium alloy or of magnesium or magnesium alloy - Google Patents
Process for treating the surface of a part made of aluminium or aluminium alloy or of magnesium or magnesium alloyInfo
- Publication number
- EP3810833A1 EP3810833A1 EP19742867.5A EP19742867A EP3810833A1 EP 3810833 A1 EP3810833 A1 EP 3810833A1 EP 19742867 A EP19742867 A EP 19742867A EP 3810833 A1 EP3810833 A1 EP 3810833A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- ions
- aqueous composition
- composition
- salt
- treatment
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000000034 method Methods 0.000 title claims abstract description 88
- 230000008569 process Effects 0.000 title claims abstract description 40
- 229910000838 Al alloy Inorganic materials 0.000 title claims abstract description 27
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 title claims abstract description 17
- 229910000861 Mg alloy Inorganic materials 0.000 title claims abstract description 15
- 229910052782 aluminium Inorganic materials 0.000 title claims abstract description 14
- 229910052749 magnesium Inorganic materials 0.000 title claims abstract description 14
- 239000011777 magnesium Substances 0.000 title claims abstract description 14
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 title claims abstract description 13
- 239000004411 aluminium Substances 0.000 title abstract 2
- 239000000203 mixture Substances 0.000 claims abstract description 99
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 15
- 230000003647 oxidation Effects 0.000 claims abstract description 14
- 150000002500 ions Chemical class 0.000 claims description 35
- 150000003839 salts Chemical class 0.000 claims description 29
- 238000011282 treatment Methods 0.000 claims description 28
- 238000002048 anodisation reaction Methods 0.000 claims description 24
- -1 cerium ions Chemical class 0.000 claims description 19
- 229910052684 Cerium Inorganic materials 0.000 claims description 16
- 229910052804 chromium Inorganic materials 0.000 claims description 16
- 239000011651 chromium Substances 0.000 claims description 16
- 238000004381 surface treatment Methods 0.000 claims description 16
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims description 15
- IIPYXGDZVMZOAP-UHFFFAOYSA-N lithium nitrate Chemical compound [Li+].[O-][N+]([O-])=O IIPYXGDZVMZOAP-UHFFFAOYSA-N 0.000 claims description 14
- 239000000126 substance Substances 0.000 claims description 13
- MEFBJEMVZONFCJ-UHFFFAOYSA-N molybdate Chemical class [O-][Mo]([O-])(=O)=O MEFBJEMVZONFCJ-UHFFFAOYSA-N 0.000 claims description 12
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 claims description 10
- 229910001416 lithium ion Inorganic materials 0.000 claims description 10
- 238000005238 degreasing Methods 0.000 claims description 7
- 229910002651 NO3 Inorganic materials 0.000 claims description 6
- 238000005554 pickling Methods 0.000 claims description 6
- 150000000703 Cerium Chemical class 0.000 claims description 5
- 229910002096 lithium permanganate Inorganic materials 0.000 claims description 4
- 229910003002 lithium salt Inorganic materials 0.000 claims description 4
- 159000000002 lithium salts Chemical class 0.000 claims description 4
- 238000007654 immersion Methods 0.000 claims description 2
- 238000007745 plasma electrolytic oxidation reaction Methods 0.000 claims description 2
- 238000012360 testing method Methods 0.000 description 52
- 230000007797 corrosion Effects 0.000 description 37
- 238000005260 corrosion Methods 0.000 description 37
- 239000010410 layer Substances 0.000 description 23
- 239000002344 surface layer Substances 0.000 description 18
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 17
- 239000007921 spray Substances 0.000 description 14
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 description 12
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 11
- 229910052744 lithium Inorganic materials 0.000 description 10
- 239000000470 constituent Substances 0.000 description 9
- HSJPMRKMPBAUAU-UHFFFAOYSA-N cerium(3+);trinitrate Chemical compound [Ce+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O HSJPMRKMPBAUAU-UHFFFAOYSA-N 0.000 description 8
- PXGOKWXKJXAPGV-UHFFFAOYSA-N Fluorine Chemical compound FF PXGOKWXKJXAPGV-UHFFFAOYSA-N 0.000 description 7
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 description 7
- 238000006243 chemical reaction Methods 0.000 description 7
- JOPOVCBBYLSVDA-UHFFFAOYSA-N chromium(6+) Chemical compound [Cr+6] JOPOVCBBYLSVDA-UHFFFAOYSA-N 0.000 description 7
- 230000000052 comparative effect Effects 0.000 description 7
- 229910052731 fluorine Inorganic materials 0.000 description 7
- 239000011737 fluorine Substances 0.000 description 7
- 239000011572 manganese Substances 0.000 description 7
- 239000011148 porous material Substances 0.000 description 7
- 229910052726 zirconium Inorganic materials 0.000 description 7
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 6
- 229910052748 manganese Inorganic materials 0.000 description 6
- 229910052750 molybdenum Inorganic materials 0.000 description 6
- 239000011733 molybdenum Substances 0.000 description 6
- XAEFZNCEHLXOMS-UHFFFAOYSA-M potassium benzoate Chemical compound [K+].[O-]C(=O)C1=CC=CC=C1 XAEFZNCEHLXOMS-UHFFFAOYSA-M 0.000 description 6
- 238000004626 scanning electron microscopy Methods 0.000 description 6
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 5
- 229910045601 alloy Inorganic materials 0.000 description 5
- 239000000956 alloy Substances 0.000 description 5
- 238000002149 energy-dispersive X-ray emission spectroscopy Methods 0.000 description 5
- 238000003754 machining Methods 0.000 description 5
- 238000007789 sealing Methods 0.000 description 5
- 159000000000 sodium salts Chemical class 0.000 description 5
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 4
- 230000007547 defect Effects 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 238000001000 micrograph Methods 0.000 description 4
- 230000010287 polarization Effects 0.000 description 4
- 238000002360 preparation method Methods 0.000 description 4
- 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 description 3
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 3
- 238000004458 analytical method Methods 0.000 description 3
- 238000001035 drying Methods 0.000 description 3
- 239000012286 potassium permanganate Substances 0.000 description 3
- 235000015393 sodium molybdate Nutrition 0.000 description 3
- 239000011684 sodium molybdate Substances 0.000 description 3
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 2
- 229910020148 K2ZrF6 Inorganic materials 0.000 description 2
- WCUXLLCKKVVCTQ-UHFFFAOYSA-M Potassium chloride Chemical compound [Cl-].[K+] WCUXLLCKKVVCTQ-UHFFFAOYSA-M 0.000 description 2
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- 239000000654 additive Substances 0.000 description 2
- 230000000996 additive effect Effects 0.000 description 2
- 150000001450 anions Chemical class 0.000 description 2
- 238000007743 anodising Methods 0.000 description 2
- 238000009835 boiling Methods 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 2
- 239000003792 electrolyte Substances 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- XLYOFNOQVPJJNP-ZSJDYOACSA-N heavy water Substances [2H]O[2H] XLYOFNOQVPJJNP-ZSJDYOACSA-N 0.000 description 2
- CKAPSXZOOQJIBF-UHFFFAOYSA-N hexachlorobenzene Chemical compound ClC1=C(Cl)C(Cl)=C(Cl)C(Cl)=C1Cl CKAPSXZOOQJIBF-UHFFFAOYSA-N 0.000 description 2
- 150000004679 hydroxides Chemical class 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 230000007246 mechanism Effects 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- 229910052700 potassium Inorganic materials 0.000 description 2
- 239000011591 potassium Substances 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 229910052709 silver Inorganic materials 0.000 description 2
- 239000004332 silver Substances 0.000 description 2
- 238000002791 soaking Methods 0.000 description 2
- 239000011780 sodium chloride Substances 0.000 description 2
- TVXXNOYZHKPKGW-UHFFFAOYSA-N sodium molybdate (anhydrous) Chemical compound [Na+].[Na+].[O-][Mo]([O-])(=O)=O TVXXNOYZHKPKGW-UHFFFAOYSA-N 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- JHWIEAWILPSRMU-UHFFFAOYSA-N 2-methyl-3-pyrimidin-4-ylpropanoic acid Chemical compound OC(=O)C(C)CC1=CC=NC=N1 JHWIEAWILPSRMU-UHFFFAOYSA-N 0.000 description 1
- DDFHBQSCUXNBSA-UHFFFAOYSA-N 5-(5-carboxythiophen-2-yl)thiophene-2-carboxylic acid Chemical compound S1C(C(=O)O)=CC=C1C1=CC=C(C(O)=O)S1 DDFHBQSCUXNBSA-UHFFFAOYSA-N 0.000 description 1
- QTBSBXVTEAMEQO-UHFFFAOYSA-M Acetate Chemical compound CC([O-])=O QTBSBXVTEAMEQO-UHFFFAOYSA-M 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 241000976924 Inca Species 0.000 description 1
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 1
- 229910021607 Silver chloride Inorganic materials 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- QFHCYMVKJALMHW-UHFFFAOYSA-J [W+4].C([O-])([O-])=O.C([O-])([O-])=O Chemical compound [W+4].C([O-])([O-])=O.C([O-])([O-])=O QFHCYMVKJALMHW-UHFFFAOYSA-J 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 229910052783 alkali metal Inorganic materials 0.000 description 1
- 150000001340 alkali metals Chemical class 0.000 description 1
- WNROFYMDJYEPJX-UHFFFAOYSA-K aluminium hydroxide Chemical class [OH-].[OH-].[OH-].[Al+3] WNROFYMDJYEPJX-UHFFFAOYSA-K 0.000 description 1
- VXAUWWUXCIMFIM-UHFFFAOYSA-M aluminum;oxygen(2-);hydroxide Chemical compound [OH-].[O-2].[Al+3] VXAUWWUXCIMFIM-UHFFFAOYSA-M 0.000 description 1
- 230000003321 amplification Effects 0.000 description 1
- 238000013475 authorization Methods 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 239000002585 base Substances 0.000 description 1
- 229910052728 basic metal Inorganic materials 0.000 description 1
- 150000003818 basic metals Chemical class 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 229910001593 boehmite Inorganic materials 0.000 description 1
- 230000000711 cancerogenic effect Effects 0.000 description 1
- 231100000315 carcinogenic Toxicity 0.000 description 1
- 238000010349 cathodic reaction Methods 0.000 description 1
- 150000001768 cations Chemical class 0.000 description 1
- 229910000420 cerium oxide Inorganic materials 0.000 description 1
- DRVWBEJJZZTIGJ-UHFFFAOYSA-N cerium(3+);oxygen(2-) Chemical class [O-2].[O-2].[O-2].[Ce+3].[Ce+3] DRVWBEJJZZTIGJ-UHFFFAOYSA-N 0.000 description 1
- 238000012512 characterization method Methods 0.000 description 1
- 229940117975 chromium trioxide Drugs 0.000 description 1
- WGLPBDUCMAPZCE-UHFFFAOYSA-N chromium trioxide Inorganic materials O=[Cr](=O)=O WGLPBDUCMAPZCE-UHFFFAOYSA-N 0.000 description 1
- GAMDZJFZMJECOS-UHFFFAOYSA-N chromium(6+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[Cr+6] GAMDZJFZMJECOS-UHFFFAOYSA-N 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000007739 conversion coating Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- BJZIJOLEWHWTJO-UHFFFAOYSA-H dipotassium;hexafluorozirconium(2-) Chemical compound [F-].[F-].[F-].[F-].[F-].[F-].[K+].[K+].[Zr+4] BJZIJOLEWHWTJO-UHFFFAOYSA-H 0.000 description 1
- 238000000840 electrochemical analysis Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000013213 extrapolation Methods 0.000 description 1
- 125000001153 fluoro group Chemical group F* 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- FAHBNUUHRFUEAI-UHFFFAOYSA-M hydroxidooxidoaluminium Chemical compound O[Al]=O FAHBNUUHRFUEAI-UHFFFAOYSA-M 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- FZLIPJUXYLNCLC-UHFFFAOYSA-N lanthanum atom Chemical compound [La] FZLIPJUXYLNCLC-UHFFFAOYSA-N 0.000 description 1
- 238000002386 leaching Methods 0.000 description 1
- 229910001234 light alloy Inorganic materials 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- YQNQTEBHHUSESQ-UHFFFAOYSA-N lithium aluminate Chemical class [Li+].[O-][Al]=O YQNQTEBHHUSESQ-UHFFFAOYSA-N 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 231100000219 mutagenic Toxicity 0.000 description 1
- 230000003505 mutagenic effect Effects 0.000 description 1
- 231100000252 nontoxic Toxicity 0.000 description 1
- 230000003000 nontoxic effect Effects 0.000 description 1
- 238000003199 nucleic acid amplification method Methods 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 239000003973 paint Substances 0.000 description 1
- JRKICGRDRMAZLK-UHFFFAOYSA-L peroxydisulfate Chemical compound [O-]S(=O)(=O)OOS([O-])(=O)=O JRKICGRDRMAZLK-UHFFFAOYSA-L 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 150000003109 potassium Chemical class 0.000 description 1
- 235000011164 potassium chloride Nutrition 0.000 description 1
- 239000001103 potassium chloride Substances 0.000 description 1
- 239000011241 protective layer Substances 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 231100001260 reprotoxic Toxicity 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 238000000550 scanning electron microscopy energy dispersive X-ray spectroscopy Methods 0.000 description 1
- HKZLPVFGJNLROG-UHFFFAOYSA-M silver monochloride Chemical compound [Cl-].[Ag+] HKZLPVFGJNLROG-UHFFFAOYSA-M 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 241000894007 species Species 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 230000008646 thermal stress Effects 0.000 description 1
- 231100000331 toxic Toxicity 0.000 description 1
- 230000002588 toxic effect Effects 0.000 description 1
- 239000003440 toxic substance Substances 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
- 229910052725 zinc 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
- C25D11/18—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
- C25D11/026—Anodisation with spark discharge
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
- C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
- C23C22/40—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing molybdates, tungstates or vanadates
- C23C22/44—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing molybdates, tungstates or vanadates containing also fluorides or complex fluorides
-
- 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
- C25D11/16—Pretreatment, e.g. desmutting
-
- 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
- C25D11/30—Anodisation of magnesium or alloys based thereon
Definitions
- the present invention is in the field of surface treatment of aluminum or magnesium alloy parts in order to protect them from corrosion.
- the present invention relates to a method of surface treatment of an aluminum or aluminum alloy or magnesium or magnesium alloy part using an aqueous composition for the surface treatment.
- the invention also relates to a part made of aluminum alloy or of magnesium alloy obtained by such a process.
- Aluminum or magnesium alloys are widely used in the aeronautical field for their low density and good mechanical properties. However, they must be protected by surface treatments to avoid corrosion.
- the parts to be treated are immersed, with an appropriate counter electrode, in a bath containing an electrolyte, in which an anode current is applied.
- a protective layer is then formed on the surface of the part, called an anode layer, which is composed mainly of oxides and hydroxides from the elements of the substrate, and in some cases elements from the electrolyte.
- the anodic layers alone are not sufficient to effectively protect the parts against corrosion, since they are generally porous, therefore sensitive to corrosion. They therefore need to be painted or sealed.
- the clogging treatments proposed for this purpose by the prior art, and implemented for many years, use potassium or sodium dichromate. Furthermore, in the case where an electrical conductivity is required for the part, the combination of anodization and clogging is replaced by a chemical conversion treatment. Currently, this treatment is most generally carried out by means of a solution based on chromium trioxide, for example by the solution sold under the name "Alodine 1200" by the company Henkel.
- the anticorrosion protection conferred by the conductive layer thus formed is less than that obtained by anodizing and then clogging, but it can also serve as a base for attachment to a paint.
- HTS hydrothermal clogging
- HWS hot water clogging
- the anodized part is immersed in boiling water or near its boiling point, generally at 98 ° C.
- the surface of the pores is then partially converted into aluminum hydroxides, in particular boehmite (AIOOH) and pseudoboehmite (AIO (OH)), which clog the pores and thus improve the corrosion resistance of the anodic layer.
- AIOOH boehmite
- AIO pseudoboehmite
- compositions based on trivalent chromium are capable of generating traces of hexavalent chromium in the layer formed on the part, in particular when they undergo aging under wet conditions, so that they too are liable to exhibit an environmental risk.
- the present invention aims to remedy the drawbacks of the solutions proposed by the prior art for the surface treatment of parts made of aluminum or magnesium alloy with a view to improving their resistance to corrosion, in particular the drawbacks set out above. , by proposing a process using a composition free of chromium and which makes it possible to replace solutions using chromium with equivalent performance in terms of corrosion resistance imparted to the treated part.
- Additional objectives of the invention are that the process is easy and quick to perform and uses little energy, and that the composition used by the process is free from any substance toxic to living organisms and the environment in general.
- the invention also aims to ensure that the capacity for resistance to corrosion of the treated part is durable over time, and that this treated part has self-healing properties of the defects formed in the coating present on its surface.
- a method of surface treatment of an aluminum or aluminum alloy or magnesium or magnesium alloy part in order to improve its resistance to corrosion.
- This method comprises a step of treatment by oxidation of the part, then a step of applying to the surface of the part, an aqueous liquid composition very suitable for use for the surface treatment of a metal part, especially aluminum or aluminum alloy or magnesium or magnesium alloy.
- This aqueous composition contains:
- composition is also free of chromium, in particular hexavalent chromium and trivalent chromium.
- chromium in particular hexavalent chromium and trivalent chromium.
- the composition is substantially free of chromium, that is to say that it does not contain chromium, or only in trace amounts.
- the composition does not contain hexavalent chromium, even in the trace state.
- trivalent chromium it is accepted within the scope of the invention that the composition may contain small amounts, for example less than 0.01% by weight.
- the surface treatment method comprises, prior to the step of applying to the surface of the part of the composition, a stage of treatment of the part by oxidation, in particular by micro-arc oxidation or even by anodic oxidation, also called anodization.
- the part treated by the method according to the invention also has a dense surface layer, and, when the treatment step is an anodization treatment step, the pores of the anodic layer which have been formed on its surface during the anodization are advantageously blocked.
- the step of applying the composition according to the invention to the surface of the part then clogs the anodic layer which has been formed during anodization.
- Anodization can be carried out according to any conventional method in itself.
- the anodization processes using chromium, in particular hexavalent chromium are preferably avoided in the context of the present invention, for obvious environmental safety reasons.
- the anodization process is chosen in particular from the processes known to those skilled in the art of sulfo-tartaric, sulfo-boric anodization, etc.
- Particularly preferred in the context of the invention are the anodic oxidation methods of sulfuric type (OAS), in particular the methods making it possible to form on the part an anodic layer of thin thickness, typically between 3 and 7 ⁇ m, commonly designated by the terms of OAS fine.
- OAS sulfuric type
- An example of such a process is described in particular in patent document FR 2 986 807.
- the invention is not however limited to such a process and can also be applied, with the same success, to the sealing of thick anodic layers larger, for example until 25 pm. It also applies, with the same success, to the clogging of the layers formed on the surface of the substrates by the micro- bow.
- the treatment method according to the invention may comprise, before applying the composition according to the invention to the surface of the part, a step of rinsing the surface of the part, for example with water, and where appropriate a drying step, such steps being entirely optional.
- the step of applying said composition can be carried out according to any conventional method in itself for the skilled person. It is preferably carried out by immersing the part in a bath of the composition according to the invention.
- the temperature of the composition is preferably advantageously between 10 and 60 ° C, preferably between 15 and 30 ° C, and preferably between 18 and 25 ° C, in particular around 20 ° C, and more generally at room temperature.
- Such a characteristic proves to be particularly advantageous with regard to the energy expenditure necessary for the implementation of the method according to the invention, which are particularly low.
- the composition according to the invention is applied to the surface of the part for a time greater than or equal to 5 minutes, preferably between 5 and 60 minutes, and preferably between 5 and 20 minutes, in particular between 8 and 15 minutes. Again, such a characteristic turns out to be particularly advantageous from an economic point of view.
- the method according to the invention makes it possible to form on the part a surface layer having a particularly good, durable corrosion resistance and a good capacity for self-healing.
- the part treated by the method according to the invention also has a dense surface layer, and, when the treatment step is a step of treatment by anodization, the pores of the anodic layer which have been formed on its surface during anodization are advantageously blocked.
- the method comprises a preliminary stage of pretreatment of the part by chemical degreasing and / or chemical pickling, also called stage of surface preparation.
- Such a prior surface preparation step advantageously makes it possible to clean the surface of the part from its dirt, oxides, etc.
- Degreasing like stripping, can be carried out in any manner known to those skilled in the art.
- Degreasing can in particular be of the solvent or alkaline type. It is, for example, an alkaline degreasing, by soaking the part, for example for 20 minutes, in an aqueous bath of temperature of 60 ° C. for example, containing the products marketed under the names Turco® 4215 NCLT and Turco ® 4215 additive, pH 9, for example at the respective concentrations of 50 g / l and 10 g / l.
- the pickling can be both acidic and alkaline. This is, for example, an acid pickling, by soaking the part, for example for 5 minutes, in an aqueous bath at a temperature of 20 ° C. for example, containing the product sold under the name Turco® Smut Go NC, for example at a concentration of 19% by volume.
- Rinses in particular with demineralized water, and at room temperature, can be carried out between the different degreasing and pickling phases, and at the end of this preliminary stage of surface treatment.
- the step of applying the composition according to the invention to the surface of the part of the surface treatment process can be carried out directly after this preliminary pretreatment step. It then performs the chemical conversion of the aluminum alloy or the magnesium alloy, to form a surface layer resistant to corrosion on the part.
- the surface treatment method comprises a final step of rinsing the surface of the part, for example with water, and if necessary a step of drying this surface.
- the method according to the invention comprises, after the step of applying the composition according to the invention to the surface of the part, no other clogging step, in particular clogging with hot water.
- the method according to the invention comprises a step of applying an aqueous composition to the surface of the part, which can thus contain:
- fluorozirconate ions preferably, fluorozirconate ions, molybdate ions, lithium ions and permanganate ions.
- composition applied to the part by a method according to the invention is advantageously usable, with high performance, as well for a post-anodization or post-oxidation micro-arc clogging treatment.
- High corrosion protection performances are also obtained both on parts obtained by rolling and on parts obtained by machining.
- This composition after its application to the surface of a part to be treated, gives the latter a corrosion resistance capacity as good, or even better, than hot water clogging solutions or commercial solutions for clogging or chemical conversion based on trivalent chromium, which are proposed by the prior art.
- part surface self-healing properties For example, no corrosion pitting appears on scratched specimens treated with the composition according to the invention, after more than 800 hours of exposure to salt spray.
- the part treated by the method according to the invention exhibits very little corrosion pitting after more than 1000 hours exposure to salt spray; it also exhibits a corrosion current, determined by the method of potentiodynamic polarization curves, which is very low.
- the fluorozirconate ions in which a zirconium atom is in complexed form with fluorine atoms, would participate in forming, on the surface of the part, a hydrated layer of Al-Zr-OF which would increase the character hydrophilic from the workpiece surface and activate it.
- the molybdate ions which have a reducible hexavalent anion which forms an insoluble oxide, would have within this surface layer an action of inhibiting corrosion.
- the lithium ions would participate in the formation of a lithium aluminate salt (LiH (AI02) 2.5H20), which would plug the pores in the surface layer of the part.
- Permanganate ions for their part, would have a self-healing effect by leaching of Mn 7+ , transport by the composition and reduction in insoluble form of manganese at the level of the defects present in the surface layer, to form clogging intermetallic precipitates therein. .
- composition applied to said part by the method according to the invention comprises one or more, preferably all, of the following characteristics:
- a concentration of hexafluorozirconate ions between 3.5 and 22 g / l, preferably between 3.5 and 9 g / l;
- a concentration of molybdate ions between 1.5 and 7 g / l, preferably between 3.5 and 7 g / l;
- a concentration of lithium ions of between 0.2 and 1 g / l, preferably of between 0.4 and 1 g / l;
- composition applied to said part by the process according to the invention may also contain cerium ions, preferably at the degree of oxidation +3. Such a characteristic further increases the anticorrosion performance of the treated part, in particular by the formation of precipitates of cerium oxides and hydroxides on the cathode sites of the metal surface, due to a strong local increase in pH.
- composition applied to said part by the method according to the invention may in particular comprise a concentration of cerium ions of between 0.01 and 0.2 g / l, preferably between 0.05 and 0.2 g / l.
- composition applied to said part by the process according to the invention also preferably contains nitrate ions.
- nitrate ions which advantageously play an oxidizing role in said composition, thus further improving the anticorrosion performance of the treated part, can for example be brought into the composition in the form of a salt, for example a lithium salt and / or cerium salt.
- all of the ions contained in the composition applied to said part by the method according to the invention can be added in the form of one or more water-soluble salts.
- the cations in particular of lithium and / or cerium, can for example be provided in the form of sulfate, persulfate, chloride, nitrate, fluoride, acetate, carbonate, etc., or any of their mixtures.
- they are provided in the form of nitrate, in particular lithium nitrate and / or cerium nitrate.
- composition applied to said part by the process according to the invention preferably contains lithium nitrate UNO3 and / or cerium nitrate, in particular cerium with an oxidation state of +3, Ce (N03) 3.
- the anions in particular of fluorozirconate, molybdate and / or permanganate, can for example be provided in the composition in the form of one or more salts of one or more alkali metals, for example in the form of a potassium or sodium salt , or their mixture.
- composition applied to said part by the process according to the invention can, for example, contain one or more of the following salts:
- composition applied to said part by the method according to the invention may for example comprise at least one, preferably several, and preferably all, of the following characteristics:
- molybdate salt for example sodium molybdate Na2Mo04, 2H2O;
- cerium salt for example nitrate of cerium Ce (N03) 3, 6H2O.
- composition applied to said part by the method according to the invention contains one of the following combinations of constituents:
- - fluorozirconate ions preferably hexafluorozirconate ions, in particular in the form of potassium salt
- molybdate ions especially in the form of the sodium salt
- lithium ions in particular in the form of lithium nitrate. It can for example essentially contain these constituents, in solution in water;
- - fluorozirconate ions preferably hexafluorozirconate ions, in particular in the form of potassium salt
- molybdate ions especially in the form of the sodium salt
- lithium ions in particular in the form of lithium nitrate
- cerium ions in particular in the form of cerium nitrate. It can for example essentially contain these constituents, in solution in water;
- - fluorozirconate ions preferably hexafluorozirconate ions, in particular in the form of potassium salt
- molybdate ions especially in the form of the sodium salt
- permanganate ions in particular in the form of potassium salt. It can for example essentially contain these constituents, in solution in water;
- - fluorozirconate ions preferably hexafluorozirconate ions, in particular in the form of potassium salt
- molybdate ions especially in the form of the sodium salt
- permanganate ions in particular in the form of potassium salt
- cerium ions in particular in the form of a cerium salt. It can for example essentially contain these constituents, in solution in water.
- a composition applied to said part by the process according to the invention preferably contains, in solution in water:
- fluorozirconate salt for example potassium hexafluorozirconate
- molybdate salt for example sodium molybdate
- lithium salt for example lithium nitrate
- permanganate salt for example potassium permanganate
- cerium salt for example cerium nitrate.
- composition applied to said part by the process according to the invention essentially contains the five constituents listed above.
- the expression “essentially contains” means the fact that the composition contains only these components, or that it also contains other components, but only in trace amounts, in non-operating amounts , that is to say having no effect on the aluminum or magnesium alloy constituting the treated part or on the surface layer formed on the surface of the latter, prior to the application of the composition according to the invention. invention on this surface, by anodization or other oxidation, or during this application.
- composition applied to said part by the method according to the invention is substantially free from one or more, and preferably all, of the following components:
- the composition applied to said part by the process according to the invention does not substantially contain, apart from the fluorozirconate ions, other ions containing fluorine.
- it is substantially free of any substance capable of releasing fluoride ions in the composition, for example ammonium fluoride, tetrafluoroboric acid, etc.
- composition is free of the compound, or that it contains it only in trace amounts, in amounts which are ineffective for the intended application.
- the pH of the composition applied to said part by the process according to the invention is preferably between 3 and 7, preferably between 4 and 6.5, and preferably between approximately 5 and approximately 6.
- a method of surface treatment of a part made of aluminum or aluminum alloy or of magnesium or magnesium alloy comprises a step of applying to the surface of said part an aqueous composition essentially comprising one or more fluorozirconate salt (s) and one or more molybdate salt (s).
- Another aspect of the invention relates to an aluminum or aluminum alloy or magnesium or magnesium alloy part obtained by a surface treatment process according to the invention.
- This part is coated with a surface layer having a particularly high resistance to corrosion as well as self-healing properties.
- This surface layer contains aluminum or magnesium; as well as zirconium, fluorine and molybdenum; and as well as lithium and / or manganese. It may also contain cerium.
- This surface layer is dense and contains uniformly ordered spheroidal aggregates.
- the pores of the layer anodic which has been formed by anodization are further advantageously closed.
- the step of applying the composition according to the invention to the surface of the part increases the thickness of the anode layer by approximately 0.1 to 2 ⁇ m, depending on the exact composition used.
- FIG. 1 shows photographs of laminated (a /) and machined (b /) specimens respectively, made of aluminum alloy, anodized and sealed according to the invention with an aqueous composition containing fluorozirconate, molybdate, lithium ions, permanganate and cerium (C4), after 750 h of exposure to salt spray;
- FIG. 2 shows analysis micrographs by scanning electron microscopy of anodized and clogged aluminum alloy test pieces in accordance with the invention, a / by an aqueous composition containing fluorozirconate, molybdate and lithium (C1) ions, b / by an aqueous composition containing fluorozirconate, molybdate, lithium and permanganate ions (C2), c / by an aqueous composition containing fluorozirconate, molybdate, lithium and cerium (C3) ions, d / by an aqueous composition containing fluorozirconate ions , molybdate, lithium, permanganate and cerium (C4); in this figure, for each test tube, the image obtained in backscattered electron mode is shown on the left and the image in secondary electronic mode on the right;
- FIG. 3 shows a photograph of a laminated test piece of aluminum alloy, anodized and sealed according to the invention with an aqueous composition containing fluorozirconate, molybdate, lithium, permanganate and cerium ions, and marked according to an X pattern by a touch of Van Laar:
- FIG. 4 shows scanning electron microscopy micrographs of anodized and clogged aluminum alloy specimens, and marked in an X pattern by a Van Laar point, before exposure to salt spray (a / ), and after 816 h of exposure to salt spray, respectively after clogging with an aqueous composition applied by the process according to the invention containing fluorozirconate, molybdate, lithium, permanganate and cerium (b /) ions and after clogging by an aqueous composition containing only fluorozirconate ions (c / and d /, at different magnifications).
- AA2024 aluminum alloy test pieces (of the following composition: 1.2 to 1.8% Mg, 0.3 to 0.9% Mn, max. 0.5% Fe, 3.8 to 4.9% Cu , max 0.25% Zn, max 0.1% Cr, max 0.15% Ti, Al for the remaining%), laminated or machined, dimensions 25x100x3 mm (for microstructural characterizations) and 150x80x3 mm ( for the salt spray tests) were treated by the process in accordance with the present invention according to the following operating conditions.
- the test pieces were first subjected to surface preparation steps. To this end, they have been successively soaked in the following baths:
- Turco® 4215 NCLT 50 50 g / l
- Turco® 4215 additive pH 9 10 g / l
- test pieces were then subjected to an anodic sulfuric oxidation treatment, conventionally in itself, according to the following parameters:
- test pieces were then subjected to a sealing treatment in accordance with the present invention. For this, they were immersed in the following aqueous composition:
- the pH of this composition is 6.
- test pieces were directly, that is to say without rinsing, exposed to salt spray for 750 or 1176 h, at a temperature between 15 and 25 ° C, according to the conditions in accordance with the standard.
- test pieces were subjected to clogging by means of the trivalent chromium-based process sold under the name SurTec® 650.
- test pieces were then sealed using the compositions applied by a process according to the invention and described in Table 2 (C1 to C4).
- the sealing conditions were 15 min at room temperature (i.e. around 21 ° C).
- test pieces were rinsed with water and dried at 60 ° C for 10 min.
- the thickness of the layer that has been formed on their surface is shown in Table 2 below.
- test pieces were subjected to the following tests.
- the technique used to characterize the behavior of the treated specimens with respect to corrosion is that of polarization curves.
- the anode and cathode curves were obtained on different samples for each of the clogging compositions studied.
- the medium was a 0.1 M NaCl solution in water, pH 5.67.
- the measurements were carried out at 25 ° C.
- the anodic and potentiodynamic polarization curves cathodic were obtained by a Gamry potentiostat / galvanostat, with a potential scanning speed of 0.5 mV / s.
- the recording of the potentiodynamic curves was carried out from the potential of the open circuit (E ocp ), measured in the absence of external current both in the anodic and cathodic directions. Individual samples were used for each potentiodynamic curve recorded.
- the open circuit potential of the samples studied was established by direct measurement of the "Eocp-t" function with respect to the same reference electrode after immersion in the 0.1 M NaCl solution up to 15 min.
- the values of the corrosion current i ⁇ rr were determined by Tafel extrapolation of the linear region of the anodic polarization curves at the corrosion potential.
- SSC stands for the standard silver electrode
- E ⁇ rr stands for the corrosion potential
- i ⁇ rr stands for the corrosion current.
- SEM Scanning electron microscopy
- EDX energy dispersive x-ray spectroscopy
- the morphology, structure and surface composition of the clogged specimens were examined by scanning electron microscopy (SEM) using a JEOL JSM 6390 electron microscope (Japan) equipped with an ultra-high resolution scanning system. (ASID-3D), under the conditions of secondary electronic image (SEI), and backscattered electrons (BEI).
- SEM scanning electron microscopy
- ASID-3D JEOL JSM 6390 electron microscope
- SEI secondary electronic image
- BEI backscattered electrons
- the electron microscope was equipped with an Oxford Instruments INCA x-sight energy dispersing spectrometer, which allows X-ray analyzes by EDX microprobe of the samples studied at a fixed point.
- nd indicates an element present but of quantity not determined
- FIG. 2 shows the micrographs obtained by SEM for the test specimens treated with the compositions applied by the method according to the invention C1 (in a /), C2 (in b /), C3 (in c /) and C4 (in d /).
- test tube treated with composition C1 (a /) is characterized by a dense surface layer with a symmetrically ordered spheroidal structure. Integral analysis from a "large" surface established the presence of zirconium, fluorine and molybdenum.
- composition C2 (b /) is covered with a dense surface layer. It also contains uniform spheroidal agglomerates containing in particular zirconium, fluorine, manganese and molybdenum.
- test tube treated with composition C3 (c /) is also covered with a dense layer of spheroidal agglomerates of two orders of different size, and of different chemical composition.
- the integral EDX analysis of a "large" surface has notably established the presence of zirconium, fluorine and molybdenum.
- the surface morphology is also a dense surface layer containing spheroidal agglomerates, and containing in particular zirconium, fluorine, manganese and molybdenum.
- Laminated test pieces of aluminum alloy AA2024, of dimensions 150 ⁇ 80 ⁇ 3 mm were treated by the process in accordance with the present invention described in example 1 above, but with the aqueous composition according to the following invention: - K 2 ZrF 6 12 g / l
- the pH of this composition is 5.82 (measured at 19.9 ° C).
- the treatment conditions with this composition are as follows: 19 ° C, 15 min.
- test pieces are marked, according to an X pattern, in accordance with standard ISO 17872, by means of a Van Laar point in tungsten carbonate.
- the marks are made in depth, so as to completely penetrate the surface layer, until reaching the basic metal alloy constituting the test piece.
- FIG. 4 shows, in a /, an analysis micrograph by scanning electron microscopy of a marked area.
- marked test tubes are also produced after anodization and clogging treatment using an aqueous composition containing only K 2 ZrF6 at a concentration of 12 g / l.
- the specimens thus marked are subjected to a salt spray exposure test for 816 h, at a temperature between 15 and 25 ° C, according to the conditions in accordance with standard NF EN ISO 9227.
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Abstract
The invention relates to a process for treating the surface of a part made of aluminium or aluminium alloy or of magnesium or magnesium alloy, comprising a step of treating said part by oxidation and a step of applying an aqueous composition to the surface of said part.
Description
PROCÉDÉ DE TRAITEMENT DE SURFACE D’UNE PIÈCE EN ALUMINIUM OU ALLIAGE D’ALUMINIUM OU EN MAGNÉSIUM OU ALLIAGE DE METHOD FOR SURFACE TREATMENT OF A PART IN ALUMINUM OR ALLOY OF ALUMINUM OR IN MAGNESIUM OR ALLOY OF
MAGNÉSIUM MAGNESIUM
La présente invention s’inscrit dans le domaine du traitement de surface des pièces en alliage d’aluminium ou de magnésium en vue de les protéger contre la corrosion. The present invention is in the field of surface treatment of aluminum or magnesium alloy parts in order to protect them from corrosion.
Plus particulièrement, la présente invention concerne un procédé de traitement de surface d’une pièce en aluminium ou alliage d’aluminium ou en magnésium ou alliage de magnésium mettant en œuvre une composition aqueuse pour le traitement de surface. L’invention concerne également une pièce en alliage d’aluminium ou en alliage de magnésium obtenue par un tel procédé. More particularly, the present invention relates to a method of surface treatment of an aluminum or aluminum alloy or magnesium or magnesium alloy part using an aqueous composition for the surface treatment. The invention also relates to a part made of aluminum alloy or of magnesium alloy obtained by such a process.
Les alliages d’aluminium ou de magnésium sont largement utilisés dans le domaine aéronautique pour leur faible densité et leurs bonnes propriétés mécaniques. Cependant, ils doivent être protégés par des traitements de surface pour éviter leur corrosion. Aluminum or magnesium alloys are widely used in the aeronautical field for their low density and good mechanical properties. However, they must be protected by surface treatments to avoid corrosion.
Un procédé largement utilisé à l’heure actuelle pour la protection des pièces en alliages d’aluminium, et plus généralement en alliages légers, est l’anodisation, également nommée oxydation anodique. Les pièces à traiter sont immergées, avec une contre-électrode appropriée, dans un bain contenant un électrolyte, dans lequel il est appliqué un courant anodique. Il se forme alors sur la surface de la pièce une couche protectrice, appelée couche anodique, qui est composée principalement d’oxydes et hydroxydes issus des éléments du substrat, et dans quelques cas d’éléments provenant de l’électrolyte. Cependant, les couches anodiques ne suffisent pas à elles seules à protéger efficacement les pièces contre la corrosion, car elles sont généralement poreuses, donc sensibles à la corrosion. Elles nécessitent donc d’être peintes ou colmatées. Les traitements de colmatage proposés à cet effet par l’art antérieur, et mis en œuvre pendant de nombreuses années, utilisent du dichromate de potassium ou de sodium.
Par ailleurs, dans le cas où une conductivité électrique est requise pour la pièce, la combinaison de l’anodisation et du colmatage est remplacée par un traitement de conversion chimique. Actuellement, ce traitement est le plus généralement réalisé au moyen d’une solution à base de trioxyde de chrome, par exemple par la solution commercialisée sous le nom « Alodine 1200 » par la société Henkel. La protection anticorrosion conférée par la couche conductrice ainsi formée est moindre que celle obtenue par anodisation puis colmatage, mais elle peut aussi servir de base d’accroche pour une peinture. A process widely used today for the protection of parts made of aluminum alloys, and more generally of light alloys, is anodization, also called anodic oxidation. The parts to be treated are immersed, with an appropriate counter electrode, in a bath containing an electrolyte, in which an anode current is applied. A protective layer is then formed on the surface of the part, called an anode layer, which is composed mainly of oxides and hydroxides from the elements of the substrate, and in some cases elements from the electrolyte. However, the anodic layers alone are not sufficient to effectively protect the parts against corrosion, since they are generally porous, therefore sensitive to corrosion. They therefore need to be painted or sealed. The clogging treatments proposed for this purpose by the prior art, and implemented for many years, use potassium or sodium dichromate. Furthermore, in the case where an electrical conductivity is required for the part, the combination of anodization and clogging is replaced by a chemical conversion treatment. Currently, this treatment is most generally carried out by means of a solution based on chromium trioxide, for example by the solution sold under the name "Alodine 1200" by the company Henkel. The anticorrosion protection conferred by the conductive layer thus formed is less than that obtained by anodizing and then clogging, but it can also serve as a base for attachment to a paint.
Ces procédés, qu’il s’agisse de colmatage post-anodisation ou de conversion chimique, mettent classiquement en œuvre des substances à base de chrome hexavalent, qui sont classées CMR (cancérogène, mutagène et reprotoxique) et qui sont aujourd’hui soumises à autorisation par la réglementation européenne REACH. These processes, whether post-anodization clogging or chemical conversion, conventionally use substances based on hexavalent chromium, which are classified CMR (carcinogenic, mutagenic and reprotoxic) and which are now subject to authorization by European REACH regulation.
Afin de remplacer ces procédés, il a été proposé par l’art antérieur diverses solutions ne mettant pas en œuvre de chrome hexavalent. In order to replace these methods, various solutions have not been proposed by the prior art which do not use hexavalent chromium.
Concernant les procédés de colmatage des couches anodiques formées par anodisation sur la surface des pièces, qui visent à fermer les pores et rendre ainsi la couche anodique chimiquement inerte, le procédé le plus couramment utilisé à l’heure actuelle est le colmatage hydrothermal (HTS), ou colmatage à l’eau chaude (HWS). La pièce anodisée est plongée dans de l’eau bouillante ou proche de son point d’ébullition, généralement à 98 °C. La surface des pores est alors partiellement convertie en hydroxydes d’aluminium, en particulier boehmite (AIOOH) et pseudoboehmite (AIO(OH)), qui bouchent les pores et améliorent ainsi la résistance à la corrosion de la couche anodique. Les principaux inconvénients de cette solution sont une consommation énergétique élevée, ainsi que des contraintes thermiques importantes qui provoquent la formation de fissures dans la couche anodique. Un tel procédé ne permet ainsi pas d’obtenir une protection anticorrosion équivalente à celle obtenue par les solutions à base de chrome hexavalent. Regarding the clogging processes of the anodic layers formed by anodization on the surface of the parts, which aim to close the pores and thus make the anodic layer chemically inert, the most commonly used process at present is hydrothermal clogging (HTS) , or hot water clogging (HWS). The anodized part is immersed in boiling water or near its boiling point, generally at 98 ° C. The surface of the pores is then partially converted into aluminum hydroxides, in particular boehmite (AIOOH) and pseudoboehmite (AIO (OH)), which clog the pores and thus improve the corrosion resistance of the anodic layer. The main disadvantages of this solution are high energy consumption, as well as significant thermal stresses which cause the formation of cracks in the anode layer. Such a process therefore does not make it possible to obtain anticorrosion protection equivalent to that obtained by solutions based on hexavalent chromium.
De nombreux travaux se sont intéressés au développement de solutions de colmatage à base de composés chimiques non toxiques. Les
procédés le plus souvent étudiés mettent en œuvre du chrome trivalent, c’est- à-dire au degré d’oxydation +3. Il existe ainsi à ce jour sur le marché des procédés pour le colmatage ou la conversion chimique des pièces en alliage d’aluminium à base de chrome trivalent, tels que la solution commercialisée sous le nom SurTec® 650 par la société SurTec®, la solution commercialisée sous le nom Lanthane 613.3 par la société Coventya, la solution commercialisée sous le nom Metalast par la société Chemetall, ou encore la solution commercialisée sous le nom Socosurf TCS/PACS par la société Socomore. Many works have been interested in the development of sealing solutions based on non-toxic chemical compounds. The Most often studied processes use trivalent chromium, that is to say at the degree of oxidation +3. To date, there are processes on the market for clogging or chemical conversion of aluminum alloy parts based on trivalent chromium, such as the solution sold under the name SurTec® 650 by the company SurTec®, the solution marketed under the name Lanthane 613.3 by the company Coventya, the solution marketed under the name Metalast by the company Chemetall, or even the solution marketed under the name Socosurf TCS / PACS by the company Socomore.
On peut également citer par exemple le procédé de traitement de surface proposé par le document US 6,669,786, qui met en œuvre plusieurs espèces ioniques métalliques, dont au moins une à l’état trivalent et au moins une à l’état hexavalent. Mention may also be made, for example, of the surface treatment method proposed by document US Pat. No. 6,669,786, which uses several metallic ionic species, at least one of which is in the trivalent state and at least one in the hexavalent state.
Cependant, ces procédés ne permettent pas de répondre à toutes les exigences du domaine aéronautique en termes de protection contre la corrosion. De plus, les compositions à base de chrome trivalent sont susceptibles de générer dans la couche formée sur la pièce des traces de chrome hexavalent, en particulier lorsqu’elles subissent un vieillissement en conditions humides, si bien qu’elles sont elles aussi susceptibles de présenter un risque environnemental. However, these methods do not make it possible to meet all the requirements of the aeronautical field in terms of protection against corrosion. In addition, compositions based on trivalent chromium are capable of generating traces of hexavalent chromium in the layer formed on the part, in particular when they undergo aging under wet conditions, so that they too are liable to exhibit an environmental risk.
La présente invention vise à remédier aux inconvénients des solutions proposées par l’art antérieur pour le traitement de surface des pièces en alliage d’aluminium ou de magnésium en vue d’en améliorer la résistance à la corrosion, notamment aux inconvénients exposés ci-avant, en proposant un procédé mettant en œuvre une composition exempte de chrome et qui permet de se substituer aux solutions utilisant du chrome avec des performances équivalentes en termes de résistance à la corrosion conférée à la pièce traitée. The present invention aims to remedy the drawbacks of the solutions proposed by the prior art for the surface treatment of parts made of aluminum or magnesium alloy with a view to improving their resistance to corrosion, in particular the drawbacks set out above. , by proposing a process using a composition free of chromium and which makes it possible to replace solutions using chromium with equivalent performance in terms of corrosion resistance imparted to the treated part.
Des objectifs supplémentaires de l’invention sont que le procédé soit facile et rapide à réaliser et peu énergivore, et que la composition mise en œuvre par le procédé soit exempte de toute substance toxique pour les organismes vivants et l’environnement en général. Additional objectives of the invention are that the process is easy and quick to perform and uses little energy, and that the composition used by the process is free from any substance toxic to living organisms and the environment in general.
L’invention vise également à ce que la capacité de résistance à la
corrosion de la pièce traitée soit durable dans le temps, et que cette pièce traitée présente des propriétés d’auto-cicatrisation des défauts formés dans le revêtement présent à sa surface. The invention also aims to ensure that the capacity for resistance to corrosion of the treated part is durable over time, and that this treated part has self-healing properties of the defects formed in the coating present on its surface.
Il a maintenant été découvert par les présents inventeurs que, de manière tout à fait surprenante, de tels objectifs sont atteints par un choix combiné particulier d’un petit nombre de constituants sous forme ionique, qui lorsqu’ils sont appliqués sur la surface de la pièce à traiter, forment à la surface de cette dernière un revêtement de conversion ionique présentant une résistance à la corrosion particulièrement élevée, ceci en une seule étape, de manière très rapide, en un temps inférieur ou égal à 15 minutes, et qui plus est à température ambiante. It has now been discovered by the present inventors that, quite surprisingly, such objectives are achieved by a particular combined choice of a small number of constituents in ionic form, which when they are applied to the surface of the part to be treated, form on the surface of the latter an ion conversion coating having a particularly high corrosion resistance, this in a single step, very quickly, in a time less than or equal to 15 minutes, and moreover at room temperature.
Ainsi, selon un premier aspect, il est proposé selon la présente invention un procédé de traitement de surface d’une pièce en aluminium ou alliage d’aluminium ou en magnésium ou alliage de magnésium, en vue d’améliorer sa résistance à la corrosion. Ce procédé comprend une étape de traitement par oxydation de la pièce, puis une étape d’application sur la surface de la pièce, d’une composition liquide aqueuse convenant tout particulièrement pour une utilisation pour le traitement de surface d’une pièce métallique, en particulier en aluminium ou alliage d’aluminium ou en magnésium ou alliage de magnésium. Cette composition aqueuse contient : Thus, according to a first aspect, there is proposed according to the present invention a method of surface treatment of an aluminum or aluminum alloy or magnesium or magnesium alloy part, in order to improve its resistance to corrosion. This method comprises a step of treatment by oxidation of the part, then a step of applying to the surface of the part, an aqueous liquid composition very suitable for use for the surface treatment of a metal part, especially aluminum or aluminum alloy or magnesium or magnesium alloy. This aqueous composition contains:
- des ions fluorozirconate, de préférence des ions hexafluorozirconate ZrFe2 , - fluorozirconate ions, preferably hexafluorozirconate ZrFe 2 ions,
- des ions molybdate M0O42 , - molybdate ions M0O4 2 ,
- et au moins un composant choisi parmi les ions lithium Li+ et les ions permanganate Mn04 . - And at least one component chosen from lithium ions Li + and permanganate ions Mn04.
Cette composition est en outre exempte de chrome, notamment de chrome hexavalent et de chrome trivalent. On entend par là que la composition est sensiblement exempte de chrome, c’est-à-dire qu’elle ne contient pas de chrome, ou seulement à l’état de traces. This composition is also free of chromium, in particular hexavalent chromium and trivalent chromium. By this is meant that the composition is substantially free of chromium, that is to say that it does not contain chromium, or only in trace amounts.
De préférence, la composition ne contient pas de chrome hexavalent, même à l’état de trace.
En ce qui concerne le chrome trivalent, on admet dans le cadre de l’invention que la composition puisse en contenir de petites quantités, par exemple inférieures à 0,01 % en poids. Preferably, the composition does not contain hexavalent chromium, even in the trace state. With regard to trivalent chromium, it is accepted within the scope of the invention that the composition may contain small amounts, for example less than 0.01% by weight.
Selon l’invention, le procédé de traitement de surface comprend, préalablement à l’étape d’application sur la surface de la pièce de la composition, une étape de traitement de la pièce par oxydation, notamment par oxydation micro-arc ou encore par oxydation anodique, également nommée anodisation. According to the invention, the surface treatment method comprises, prior to the step of applying to the surface of the part of the composition, a stage of treatment of the part by oxidation, in particular by micro-arc oxidation or even by anodic oxidation, also called anodization.
La pièce traitée par le procédé selon l’invention présente en outre une couche de surface dense, et, lorsque l’étape de traitement est une étape de traitement par anodisation, les pores de la couche anodique qui ont été formés sur sa surface lors de l’anodisation sont avantageusement bouchés. The part treated by the method according to the invention also has a dense surface layer, and, when the treatment step is an anodization treatment step, the pores of the anodic layer which have been formed on its surface during the anodization are advantageously blocked.
L’étape d’application de la composition selon l’invention sur la surface de la pièce réalise alors le colmatage de la couche anodique qui a été formée lors de l’anodisation. The step of applying the composition according to the invention to the surface of the part then clogs the anodic layer which has been formed during anodization.
L’anodisation peut être réalisée selon toute méthode classique en elle- même. Toutefois, les procédés d’anodisation mettant en œuvre du chrome, notamment du chrome hexavalent, sont préférentiellement évités dans le cadre de la présente invention, pour des raisons de sécurité environnementale évidentes. Anodization can be carried out according to any conventional method in itself. However, the anodization processes using chromium, in particular hexavalent chromium, are preferably avoided in the context of the present invention, for obvious environmental safety reasons.
Le procédé d’anodisation est notamment choisi parmi les procédés connus de l’homme du métier d’anodisation sulfo-tartrique, sulfo-borique, etc. Sont particulièrement préférés dans le cadre de l’invention les procédés d’oxydation anodique de type sulfurique (OAS), notamment les procédés permettant de former sur la pièce une couche anodique de fine épaisseur, typiquement comprise entre 3 et 7 pm, couramment désignés par les termes d’OAS fine. Un exemple de tel procédé est notamment décrit dans le document de brevet FR 2 986 807. L’invention ne se limite cependant pas à un tel procédé et peut également s’appliquer, avec le même succès, au colmatage des couches anodiques d’épaisseur plus importante, par exemple jusqu’à 25 pm. Elle s’applique également, avec le même succès, au colmatage des couches formées en surface des substrats par la technique d’oxydation micro-
arc. The anodization process is chosen in particular from the processes known to those skilled in the art of sulfo-tartaric, sulfo-boric anodization, etc. Particularly preferred in the context of the invention are the anodic oxidation methods of sulfuric type (OAS), in particular the methods making it possible to form on the part an anodic layer of thin thickness, typically between 3 and 7 μm, commonly designated by the terms of OAS fine. An example of such a process is described in particular in patent document FR 2 986 807. The invention is not however limited to such a process and can also be applied, with the same success, to the sealing of thick anodic layers larger, for example until 25 pm. It also applies, with the same success, to the clogging of the layers formed on the surface of the substrates by the micro- bow.
A l’issue de l’étape d’anodisation, le procédé de traitement selon l’invention peut comprendre, préalablement à l’application de la composition selon l’invention sur la surface de la pièce, une étape de rinçage de la surface de la pièce, par exemple à l‘eau, et le cas échéant une étape de séchage, de telles étapes étant entièrement facultatives. At the end of the anodization step, the treatment method according to the invention may comprise, before applying the composition according to the invention to the surface of the part, a step of rinsing the surface of the part, for example with water, and where appropriate a drying step, such steps being entirely optional.
L’étape d’application de ladite composition peut être réalisée selon toute méthode classique en elle-même pour l’homme du métier. Elle est de préférence réalisée par immersion de la pièce dans un bain de la composition selon l’invention. The step of applying said composition can be carried out according to any conventional method in itself for the skilled person. It is preferably carried out by immersing the part in a bath of the composition according to the invention.
Autrement, elle peut être réalisée par pulvérisation, application au tampon, etc. Otherwise, it can be carried out by spraying, application with a tampon, etc.
Pour cette étape, la température de la composition est de préférence avantageusement comprise entre 10 et 60 °C, de préférence comprise entre 15 et 30 °C, et préférentiellement comprise entre 18 et 25 °C, notamment d’environ 20 °C, et plus généralement à température ambiante. Une telle caractéristique s’avère particulièrement avantageuse en ce qui concerne les dépenses en énergie nécessaires à la mise en œuvre du procédé selon l’invention, qui sont particulièrement faibles. For this step, the temperature of the composition is preferably advantageously between 10 and 60 ° C, preferably between 15 and 30 ° C, and preferably between 18 and 25 ° C, in particular around 20 ° C, and more generally at room temperature. Such a characteristic proves to be particularly advantageous with regard to the energy expenditure necessary for the implementation of the method according to the invention, which are particularly low.
Dans des modes de mise en œuvre préférés de l’invention, l’application de la composition selon l’invention sur la surface de la pièce est réalisée pendant un temps supérieur ou égal à 5 minutes, de préférence compris entre 5 et 60 minutes, et préférentiellement compris entre 5 et 20 minutes, notamment entre 8 et 15 minutes. Là encore, une telle caractéristique s’avère particulièrement avantageuse d’un point de vue économique. In preferred embodiments of the invention, the composition according to the invention is applied to the surface of the part for a time greater than or equal to 5 minutes, preferably between 5 and 60 minutes, and preferably between 5 and 20 minutes, in particular between 8 and 15 minutes. Again, such a characteristic turns out to be particularly advantageous from an economic point of view.
Le procédé selon l’invention permet de former sur la pièce une couche de surface présentant une résistance à la corrosion particulièrement bonne, durable, et une bonne capacité d’auto-cicatrisation. The method according to the invention makes it possible to form on the part a surface layer having a particularly good, durable corrosion resistance and a good capacity for self-healing.
La pièce traitée par le procédé selon l’invention présente en outre une couche de surface dense, et, lorsque l’étape de traitement est une étape de
traitement par anodisation, les pores de la couche anodique qui ont été formés sur sa surface lors de l’anodisation sont avantageusement bouchés. The part treated by the method according to the invention also has a dense surface layer, and, when the treatment step is a step of treatment by anodization, the pores of the anodic layer which have been formed on its surface during anodization are advantageously blocked.
Dans des modes de mise en œuvre particuliers de l’invention, le procédé comprend une étape préalable de prétraitement de la pièce par dégraissage chimique et/ou décapage chimique, également nommée étape de préparation de surface. In particular embodiments of the invention, the method comprises a preliminary stage of pretreatment of the part by chemical degreasing and / or chemical pickling, also called stage of surface preparation.
Une telle étape préalable de préparation de surface permet avantageusement de nettoyer la surface de la pièce de ses salissures, oxydes, etc. Such a prior surface preparation step advantageously makes it possible to clean the surface of the part from its dirt, oxides, etc.
Le dégraissage, tout comme le décapage, peuvent être réalisés de toute manière connue de l’homme du métier. Degreasing, like stripping, can be carried out in any manner known to those skilled in the art.
Le dégraissage peut notamment être du type au solvant ou alcalin. Il s’agit par exemple d’un dégraissage alcalin, par trempage de la pièce, par exemple pendant 20 minutes, dans un bain aqueux de température de 60 °C par exemple, contenant les produits commercialisés sous les noms Turco® 4215 NCLT et Turco® 4215 additif, de pH 9, par exemple aux concentrations respectives de 50 g/l et 10 g/l. Degreasing can in particular be of the solvent or alkaline type. It is, for example, an alkaline degreasing, by soaking the part, for example for 20 minutes, in an aqueous bath of temperature of 60 ° C. for example, containing the products marketed under the names Turco® 4215 NCLT and Turco ® 4215 additive, pH 9, for example at the respective concentrations of 50 g / l and 10 g / l.
Le décapage peut quant à lui aussi bien être de type acide que de type alcalin. Il s’agit par exemple d’un décapage acide, par trempage de la pièce, par exemple pendant 5 minutes, dans un bain aqueux de température de 20 °C par exemple, contenant le produit commercialisé sous le nom Turco® Smut Go NC, par exemple à la concentration de 19 % en volume. The pickling can be both acidic and alkaline. This is, for example, an acid pickling, by soaking the part, for example for 5 minutes, in an aqueous bath at a temperature of 20 ° C. for example, containing the product sold under the name Turco® Smut Go NC, for example at a concentration of 19% by volume.
Des rinçages, notamment à l’eau déminéralisée, et à température ambiante, peuvent être réalisés entre les différentes phases de dégraissage et de décapage, et à l’issue de cette étape préalable de traitement de surface. Rinses, in particular with demineralized water, and at room temperature, can be carried out between the different degreasing and pickling phases, and at the end of this preliminary stage of surface treatment.
L’étape d’application de la composition selon l’invention sur la surface de la pièce du procédé de traitement de surface peut être réalisée directement après cette étape préalable de prétraitement. Elle réalise alors la conversion chimique de l’alliage d’aluminium ou de l’alliage de magnésium, pour former une couche superficielle résistante à la corrosion sur la pièce. The step of applying the composition according to the invention to the surface of the part of the surface treatment process can be carried out directly after this preliminary pretreatment step. It then performs the chemical conversion of the aluminum alloy or the magnesium alloy, to form a surface layer resistant to corrosion on the part.
Dans des modes de mise en œuvre particuliers de l’invention, le
procédé de traitement de surface comprend une étape finale de rinçage de la surface de la pièce, par exemple à l’eau, et le cas échéant une étape de séchage de cette surface. In particular embodiments of the invention, the surface treatment method comprises a final step of rinsing the surface of the part, for example with water, and if necessary a step of drying this surface.
Préférentiellement, le procédé selon l’invention ne comporte, après l’étape d’application de la composition selon l’invention sur la surface de la pièce, aucune autre étape de colmatage, notamment de colmatage à l’eau chaude. Preferably, the method according to the invention comprises, after the step of applying the composition according to the invention to the surface of the part, no other clogging step, in particular clogging with hot water.
Le procédé selon l’invention comprend une étape d’application sur la surface de la pièce d’une composition aqueuse pouvant ainsi contenir : The method according to the invention comprises a step of applying an aqueous composition to the surface of the part, which can thus contain:
- des ions fluorozirconate, des ions molybdate et des ions lithium, - fluorozirconate ions, molybdate ions and lithium ions,
- ou bien des ions fluorozirconate, des ions molybdate et des ions permanganate, - or else fluorozirconate ions, molybdate ions and permanganate ions,
- ou bien encore, préférentiellement, des ions fluorozirconate, des ions molybdate, des ions lithium et des ions permanganate. - Or alternatively, preferably, fluorozirconate ions, molybdate ions, lithium ions and permanganate ions.
La composition appliquée sur la pièce par un procédé selon l’invention est avantageusement utilisable, avec des performances élevées, aussi bien pour un traitement de colmatage post-anodisation ou post-oxydation micro-arc. Des performances élevées de protection contre la corrosion sont en outre obtenues aussi bien sur des pièces obtenues par laminage que sur des pièces obtenues par usinage. The composition applied to the part by a method according to the invention is advantageously usable, with high performance, as well for a post-anodization or post-oxidation micro-arc clogging treatment. High corrosion protection performances are also obtained both on parts obtained by rolling and on parts obtained by machining.
Cette composition, après son application sur la surface d’une pièce à traiter, confère à cette dernière une capacité de résistance à la corrosion aussi bonne, voire meilleure, que les solutions de colmatage à l’eau chaude ou les solutions commerciales pour le colmatage ou la conversion chimique à base de chrome trivalent, qui sont proposées par l’art antérieur. This composition, after its application to the surface of a part to be treated, gives the latter a corrosion resistance capacity as good, or even better, than hot water clogging solutions or commercial solutions for clogging or chemical conversion based on trivalent chromium, which are proposed by the prior art.
Elle confère également à la pièce des propriétés d’auto-cicatrisation de surface. A titre d’exemple, aucune piqûre de corrosion n’apparait sur des éprouvettes rayées traitées par la composition selon l’invention, après plus de 800 heures d’exposition au brouillard salin. It also gives the part surface self-healing properties. For example, no corrosion pitting appears on scratched specimens treated with the composition according to the invention, after more than 800 hours of exposure to salt spray.
En particulier, la pièce traitée par le procédé selon l’invention ne présente que très peu de piqûres de corrosion après plus de 1000 heures
d’exposition au brouillard salin ; elle présente en outre un courant de corrosion, déterminé par la méthode des courbes de polarisation potentiodynamiques, qui est très faible. In particular, the part treated by the method according to the invention exhibits very little corrosion pitting after more than 1000 hours exposure to salt spray; it also exhibits a corrosion current, determined by the method of potentiodynamic polarization curves, which is very low.
On ne préjugera pas ici des mécanismes sous-tendant l’effet de tels résultats avantageux. Il résulte du traitement de la pièce par le procédé selon l’invention la formation, sur la pièce, d’une couche de surface contenant, en plus de l’aluminium ou du magnésium, du zirconium, du fluor, du molybdène, ainsi que du lithium et/ou du manganèse. Au sein de cette couche, chacun de ces éléments joue un rôle pour la protection anticorrosion, individuellement mais également surtout en synergie avec les autres éléments présents. We will not prejudge here the mechanisms underlying the effect of such advantageous results. It results from the treatment of the part by the method according to the invention the formation, on the part, of a surface layer containing, in addition to aluminum or magnesium, zirconium, fluorine, molybdenum, as well as lithium and / or manganese. Within this layer, each of these elements plays a role in corrosion protection, individually but also above all in synergy with the other elements present.
Il a été décrit dans la littérature des mécanismes d’action possibles de chaque constituant individuel de la composition selon l’invention. The mechanisms of action of each individual constituent of the composition according to the invention have been described in the literature.
A titre d’exemple, les ions fluorozirconate, dans lesquels un atome de zirconium est sous forme complexée avec des atomes de fluor, participeraient à former, à la surface de la pièce, une couche hydratée de Al-Zr-O-F qui augmenterait le caractère hydrophile de la surface de la pièce et l’activerait. Les ions molybdate, qui possèdent un anion hexavalent réductible qui forme un oxyde insoluble, auraient au sein de cette couche de surface une action d’inhibition de la corrosion. Les ions lithium participeraient à la formation d’un sel d’aluminate de lithium (LiH(AI02)2.5H20), qui colmaterait les pores dans la couche de surface de la pièce. Les ions permanganate, quant à eux, présenteraient un effet auto-cicatrisant par lixiviation de Mn7+, transport par la composition et réduction sous forme insoluble de manganèse au niveau des défauts présents dans la couche de surface, pour y former des précipités intermétalliques colmatants. For example, the fluorozirconate ions, in which a zirconium atom is in complexed form with fluorine atoms, would participate in forming, on the surface of the part, a hydrated layer of Al-Zr-OF which would increase the character hydrophilic from the workpiece surface and activate it. The molybdate ions, which have a reducible hexavalent anion which forms an insoluble oxide, would have within this surface layer an action of inhibiting corrosion. The lithium ions would participate in the formation of a lithium aluminate salt (LiH (AI02) 2.5H20), which would plug the pores in the surface layer of the part. Permanganate ions, for their part, would have a self-healing effect by leaching of Mn 7+ , transport by the composition and reduction in insoluble form of manganese at the level of the defects present in the surface layer, to form clogging intermetallic precipitates therein. .
Cependant, ces hypothèses individuelles ne permettent pas d’expliquer les performances importantes, en termes de résistance à la corrosion et d’auto-cicatrisation, de la couche superficielle formée sur les pièces par traitement au moyen de la composition mise en œuvre par le procédé selon l’invention. Rien ne permettait de penser que, combinés ensemble, ces constituants permettraient d’obtenir des performances aussi élevées en un temps de traitement aussi court et qui plus est à température
ambiante, c’est-à-dire à une température comprise entre 18 et 25 °C environ, sans qu’il soit besoin de chauffer ou d’apporter une quelconque énergie extérieure. However, these individual assumptions do not explain the significant performance, in terms of corrosion resistance and self-healing, of the surface layer formed on the parts by treatment using the composition used by the process. according to the invention. There was nothing to suggest that, combined together, these constituents would make it possible to obtain such high performance in such a short treatment time and moreover at temperature. room, that is to say at a temperature between 18 and 25 ° C, without the need to heat or provide any external energy.
Préférentiellement, la composition appliquée sur ladite pièce par le procédé selon l’invention comprend l’une ou plusieurs, de préférence l’ensemble, des caractéristiques suivantes : Preferably, the composition applied to said part by the method according to the invention comprises one or more, preferably all, of the following characteristics:
- une concentration en ions hexafluorozirconate comprise entre 3,5 et 22 g/l, de préférence comprise entre 3,5 et 9 g/l ; - A concentration of hexafluorozirconate ions between 3.5 and 22 g / l, preferably between 3.5 and 9 g / l;
- une concentration en ions molybdate comprise entre 1 ,5 et 7 g/l, de préférence comprise entre 3,5 et 7 g/l ; - A concentration of molybdate ions between 1.5 and 7 g / l, preferably between 3.5 and 7 g / l;
- une concentration en ions lithium comprise entre 0,2 et 1 g/l, de préférence comprise entre 0,4 et 1 g/l ; a concentration of lithium ions of between 0.2 and 1 g / l, preferably of between 0.4 and 1 g / l;
- et/ou une concentration en ions permanganate comprise entre 3 et 15 g/l, de préférence comprise entre 6 et 15 g/l. - And / or a permanganate ion concentration of between 3 and 15 g / l, preferably between 6 and 15 g / l.
La composition appliquée sur ladite pièce par le procédé selon l’invention peut en outre contenir des ions cérium, de préférence au degré d’oxydation +3. Une telle caractéristique augmente davantage les performances anticorrosion de la pièce traitée, notamment par formation de précipités d’oxydes et hydroxydes de cérium sur les sites cathodiques de la surface métallique, en raison d’une forte augmentation locale du pH. The composition applied to said part by the process according to the invention may also contain cerium ions, preferably at the degree of oxidation +3. Such a characteristic further increases the anticorrosion performance of the treated part, in particular by the formation of precipitates of cerium oxides and hydroxides on the cathode sites of the metal surface, due to a strong local increase in pH.
La composition appliquée sur ladite pièce par le procédé selon l’invention peut notamment comprendre une concentration en ions cérium comprise entre 0,01 et 0,2 g/l, de préférence comprise entre 0,05 et 0,2 g/l. The composition applied to said part by the method according to the invention may in particular comprise a concentration of cerium ions of between 0.01 and 0.2 g / l, preferably between 0.05 and 0.2 g / l.
La composition appliquée sur ladite pièce par le procédé selon l’invention contient également préférentiellement des ions nitrates. Ces ions nitrates, qui jouent avantageusement un rôle d’oxydant dans ladite composition, améliorant ainsi plus encore les performances anticorrosion de la pièce traitée, peuvent par exemple être apportés dans la composition sous forme de sel, par exemple de sel de lithium et/ou de sel de cérium. The composition applied to said part by the process according to the invention also preferably contains nitrate ions. These nitrate ions, which advantageously play an oxidizing role in said composition, thus further improving the anticorrosion performance of the treated part, can for example be brought into the composition in the form of a salt, for example a lithium salt and / or cerium salt.
De manière générale, l’ensemble des ions contenus dans la composition appliquée sur ladite pièce par le procédé selon l’invention peuvent
y être apportés sous forme d’un ou plusieurs sels solubles dans l’eau. In general, all of the ions contained in the composition applied to said part by the method according to the invention can be added in the form of one or more water-soluble salts.
Les cations, notamment de lithium et/ou cérium, peuvent par exemple être apportés sous forme de sulfate, persulfate, chlorure, nitrate, fluorure, acétate, carbonate, etc., ou l’un quelconque de leurs mélanges. Préférentiellement, ils sont apportés sous forme de nitrate, notamment de nitrate de lithium et/ou de nitrate de cérium. The cations, in particular of lithium and / or cerium, can for example be provided in the form of sulfate, persulfate, chloride, nitrate, fluoride, acetate, carbonate, etc., or any of their mixtures. Preferably, they are provided in the form of nitrate, in particular lithium nitrate and / or cerium nitrate.
Ainsi, la composition appliquée sur ladite pièce par le procédé selon l’invention contient de préférence du nitrate de lithium UNO3 et/ou du nitrate de cérium, en particulier de cérium au degré d’oxydation +3, Ce(N03)3. Thus, the composition applied to said part by the process according to the invention preferably contains lithium nitrate UNO3 and / or cerium nitrate, in particular cerium with an oxidation state of +3, Ce (N03) 3.
Les anions, notamment de fluorozirconate, molybdate et/ou permanganate, peuvent par exemple être apportés dans la composition sous forme d’un ou plusieurs sels d’un ou plusieurs métaux alcalins, par exemple sous forme d’un sel de potassium ou de sodium, ou leur mélange. The anions, in particular of fluorozirconate, molybdate and / or permanganate, can for example be provided in the composition in the form of one or more salts of one or more alkali metals, for example in the form of a potassium or sodium salt , or their mixture.
Ainsi, la composition appliquée sur ladite pièce par le procédé selon l’invention peut par exemple contenir l’un ou plusieurs des sels suivants : Thus, the composition applied to said part by the process according to the invention can, for example, contain one or more of the following salts:
- hexafluorozirconate de potassium fcZrFe - potassium hexafluorozirconate fcZrFe
- molybdate de sodium Na2Mo04 - sodium molybdate Na2Mo04
- permanganate de potassium KMn04. - potassium permanganate KMn04.
La composition appliquée sur ladite pièce par le procédé selon l’invention peut par exemple comprendre au moins une, de préférence plusieurs, et préférentiellement l’ensemble, des caractéristiques suivantes : The composition applied to said part by the method according to the invention may for example comprise at least one, preferably several, and preferably all, of the following characteristics:
- une concentration comprise entre 5 et 30 g/l, de préférence entre 5 et 12 g/l de sel(s) de fluorozirconate, par exemple de fluorozirconate de potassium K2ZrF6 ; - A concentration of between 5 and 30 g / l, preferably between 5 and 12 g / l of fluorozirconate salt (s), for example potassium fluorozirconate K2ZrF6;
- une concentration comprise entre 2,5 et 10 g/l, de préférence entre 5 et 10 g/l de sel(s) de molybdate, par exemple de molybdate de sodium Na2Mo04, 2H2O ; - A concentration of between 2.5 and 10 g / l, preferably between 5 and 10 g / l of molybdate salt (s), for example sodium molybdate Na2Mo04, 2H2O;
- une concentration comprise entre 2 et 8 g/l, de préférence entre 4 et 8 g/l de sel(s) de lithium, par exemple de nitrate de lithium UNO3 ; et/ou une concentration comprise entre 4 et 19 g/l, de préférence
entre 9 et 19 g/l de sel(s) de permanganate, par exemple de permanganate de potassium KMhq4 ; - A concentration of between 2 and 8 g / l, preferably between 4 and 8 g / l of lithium salt (s), for example lithium nitrate UNO3; and / or a concentration between 4 and 19 g / l, preferably between 9 and 19 g / l of permanganate salt (s), for example potassium permanganate KMhq4;
- et/ou, le cas échéant, une concentration comprise entre 0,1 et 0,5 g/l, de préférence entre 0,2 et 0,5 g/l de sel(s) de cérium, par exemple de nitrate de cérium Ce(N03)3, 6H2O. - And / or, where appropriate, a concentration of between 0.1 and 0.5 g / l, preferably between 0.2 and 0.5 g / l of cerium salt (s), for example nitrate of cerium Ce (N03) 3, 6H2O.
Ces concentrations sont les concentrations totales des sel(s) concernés. These concentrations are the total concentrations of the salt (s) concerned.
Dans des modes de réalisation particuliers de l’invention, la composition appliquée sur ladite pièce par le procédé selon l’invention contient l’une des combinaisons de constituants suivantes : In particular embodiments of the invention, the composition applied to said part by the method according to the invention contains one of the following combinations of constituents:
- des ions fluorozirconate, de préférence des ions hexafluorozirconate, notamment sous forme de sel de potassium ; des ions molybdate, notamment sous forme de sel de sodium ; et des ions lithium, notamment sous forme de nitrate de lithium. Elle peut par exemple contenir essentiellement ces constituants, en solution dans l’eau ; - fluorozirconate ions, preferably hexafluorozirconate ions, in particular in the form of potassium salt; molybdate ions, especially in the form of the sodium salt; and lithium ions, in particular in the form of lithium nitrate. It can for example essentially contain these constituents, in solution in water;
- des ions fluorozirconate, de préférence des ions hexafluorozirconate, notamment sous forme de sel de potassium ; des ions molybdate, notamment sous forme de sel de sodium ; des ions lithium, notamment sous forme de nitrate de lithium ; et des ions cérium, notamment sous forme de nitrate de cérium. Elle peut par exemple contenir essentiellement ces constituants, en solution dans l’eau ; - fluorozirconate ions, preferably hexafluorozirconate ions, in particular in the form of potassium salt; molybdate ions, especially in the form of the sodium salt; lithium ions, in particular in the form of lithium nitrate; and cerium ions, in particular in the form of cerium nitrate. It can for example essentially contain these constituents, in solution in water;
- des ions fluorozirconate, de préférence des ions hexafluorozirconate, notamment sous forme de sel de potassium ; des ions molybdate, notamment sous forme de sel de sodium ; et des ions permanganate, notamment sous forme de sel de potassium. Elle peut par exemple contenir essentiellement ces constituants, en solution dans l’eau ; - fluorozirconate ions, preferably hexafluorozirconate ions, in particular in the form of potassium salt; molybdate ions, especially in the form of the sodium salt; and permanganate ions, in particular in the form of potassium salt. It can for example essentially contain these constituents, in solution in water;
- des ions fluorozirconate, de préférence des ions hexafluorozirconate, notamment sous forme de sel de potassium ;
des ions molybdate, notamment sous forme de sel de sodium ; des ions permanganate, notamment sous forme de sel de potassium ; et des ions cérium, notamment sous forme de sel de cérium. Elle peut par exemple contenir essentiellement ces constituants, en solution dans l’eau. - fluorozirconate ions, preferably hexafluorozirconate ions, in particular in the form of potassium salt; molybdate ions, especially in the form of the sodium salt; permanganate ions, in particular in the form of potassium salt; and cerium ions, in particular in the form of a cerium salt. It can for example essentially contain these constituents, in solution in water.
Une composition appliquée sur ladite pièce par le procédé selon l’invention contient de préférence, en solution dans l’eau : A composition applied to said part by the process according to the invention preferably contains, in solution in water:
- un sel de fluorozirconate, par exemple de l’hexafluorozirconate de potassium, - a fluorozirconate salt, for example potassium hexafluorozirconate,
- un sel de molybdate, par exemple du molybdate de sodium, a molybdate salt, for example sodium molybdate,
- un sel de lithium, par exemple du nitrate de lithium, a lithium salt, for example lithium nitrate,
- un sel de permanganate, par exemple du permanganate de potassium, - a permanganate salt, for example potassium permanganate,
- et, le cas échéant, un sel de cérium, par exemple du nitrate de cérium. - And, if necessary, a cerium salt, for example cerium nitrate.
Préférentiellement, la composition appliquée sur ladite pièce par le procédé selon l’invention contient essentiellement les cinq constituants énumérés ci-dessus. Preferably, the composition applied to said part by the process according to the invention essentially contains the five constituents listed above.
On entend dans la présente description, par l’expression « contient essentiellement », le fait que la composition contient uniquement ces composants, ou qu’elle contient également d’autres composants, mais uniquement à l’état de traces, en quantités non opérantes, c’est-à-dire n’ayant aucun effet sur l’alliage d’aluminium ou de magnésium constituant la pièce traitée ou sur la couche superficielle formée à la surface de cette dernière, préalablement à l’application de la composition selon l’invention sur cette surface, par anodisation ou autre oxydation, ou lors de cette application. In the present description, the expression “essentially contains” means the fact that the composition contains only these components, or that it also contains other components, but only in trace amounts, in non-operating amounts , that is to say having no effect on the aluminum or magnesium alloy constituting the treated part or on the surface layer formed on the surface of the latter, prior to the application of the composition according to the invention. invention on this surface, by anodization or other oxidation, or during this application.
Préférentiellement, la composition appliquée sur ladite pièce par le procédé selon l’invention est sensiblement exempte d’un ou plusieurs, et de préférence la totalité, des composants suivants : Preferably, the composition applied to said part by the method according to the invention is substantially free from one or more, and preferably all, of the following components:
- ions phosphates
- vanadium, - phosphate ions - vanadium,
- et/ou peroxyde d’hydrogène. - and / or hydrogen peroxide.
En outre et de préférence, la composition appliquée sur ladite pièce par le procédé selon l’invention ne contient sensiblement pas, outre les ions fluorozirconate, d’autres ions contenant du fluor. En particulier, elle est sensiblement exempte de toute substance susceptible de libérer des ions fluorure dans la composition, par exemple de fluorure d’ammonium, d’acide tétrafluoroborique, etc. In addition and preferably, the composition applied to said part by the process according to the invention does not substantially contain, apart from the fluorozirconate ions, other ions containing fluorine. In particular, it is substantially free of any substance capable of releasing fluoride ions in the composition, for example ammonium fluoride, tetrafluoroboric acid, etc.
On entend dans la présente description, par sensiblement exempte, que la composition est exempte du composé, ou qu’elle le contient seulement à l’état de traces, dans des quantités inopérantes pour l’application visée. It is understood in the present description, by substantially free, that the composition is free of the compound, or that it contains it only in trace amounts, in amounts which are ineffective for the intended application.
Le pH de la composition appliquée sur ladite pièce par le procédé selon l’invention est préférentiellement compris entre 3 et 7, de préférence compris entre 4 et 6,5, et préférentiellement entre environ 5 et environ 6. The pH of the composition applied to said part by the process according to the invention is preferably between 3 and 7, preferably between 4 and 6.5, and preferably between approximately 5 and approximately 6.
Selon un autre aspect de l’invention, un procédé de traitement de surface d’une pièce en aluminium ou alliage d’aluminium ou en magnésium ou alliage de magnésium comprend une étape d’application sur la surface de ladite pièce d’une composition aqueuse comprenant essentiellement un ou plusieurs sel(s) de fluorozirconate et un ou plusieurs sel(s) de molybdate. According to another aspect of the invention, a method of surface treatment of a part made of aluminum or aluminum alloy or of magnesium or magnesium alloy comprises a step of applying to the surface of said part an aqueous composition essentially comprising one or more fluorozirconate salt (s) and one or more molybdate salt (s).
Un autre aspect de l’invention concerne une pièce en aluminium ou alliage d’aluminium ou en magnésium ou alliage de magnésium obtenue par un procédé de traitement de surface selon l’invention. Another aspect of the invention relates to an aluminum or aluminum alloy or magnesium or magnesium alloy part obtained by a surface treatment process according to the invention.
Cette pièce est revêtue d’une couche de surface présentant une résistance particulièrement élevée à la corrosion ainsi que des propriétés d’auto-cicatrisation. Cette couche de surface contient de l’aluminium ou du magnésium ; ainsi que du zirconium, du fluor et du molybdène ; et ainsi que du lithium et/ou du manganèse. Elle peut également contenir du cérium. This part is coated with a surface layer having a particularly high resistance to corrosion as well as self-healing properties. This surface layer contains aluminum or magnesium; as well as zirconium, fluorine and molybdenum; and as well as lithium and / or manganese. It may also contain cerium.
Cette couche de surface est dense et elle contient des agrégats sphéroïdaux uniformément ordonnés. This surface layer is dense and contains uniformly ordered spheroidal aggregates.
Lorsque l’étape d’application de la composition sur la surface de la pièce est réalisée après une étape d’anodisation, les pores de la couche
anodique qui a été formée par anodisation sont en outre avantageusement obturés. L’étape d’application de la composition selon l’invention sur la surface de la pièce augmente l’épaisseur de la couche anodique d’environ 0,1 à 2 pm, en fonction de la composition exacte mise en œuvre. When the step of applying the composition to the surface of the part is carried out after an anodizing step, the pores of the layer anodic which has been formed by anodization are further advantageously closed. The step of applying the composition according to the invention to the surface of the part increases the thickness of the anode layer by approximately 0.1 to 2 μm, depending on the exact composition used.
Par ailleurs, rien n’empêche d’appliquer l’une des compositions mise en œuvre par un procédé selon l’une des variantes de réalisation de l’invention décrites ci-dessus, lors d’un traitement de conversion chimique, directement sur des pièces non préalablement traitées par anodisation. Furthermore, nothing prevents the application of one of the compositions used by a process according to one of the variant embodiments of the invention described above, during a chemical conversion treatment, directly on parts not previously treated by anodization.
Les caractéristiques et avantages de l’invention apparaîtront plus clairement à la lumière des exemples de mise en œuvre ci-après, fournis à simple titre illustratif et nullement limitatifs de l’invention, avec l’appui des figures 1 à 4, dans lesquelles : The characteristics and advantages of the invention will appear more clearly in the light of the following implementation examples, provided for illustrative purposes only and in no way limitative of the invention, with the support of FIGS. 1 to 4, in which:
- la figure 1 montre des photographies d’éprouvettes respectivement laminée (a/) et usinée (b/), en alliage d’aluminium, anodisées et colmatées conformément à l’invention par une composition aqueuse contenant des ions fluorozirconate, molybdate, lithium, permanganate et cérium (C4), après 750 h d’exposition au brouillard salin ; FIG. 1 shows photographs of laminated (a /) and machined (b /) specimens respectively, made of aluminum alloy, anodized and sealed according to the invention with an aqueous composition containing fluorozirconate, molybdate, lithium ions, permanganate and cerium (C4), after 750 h of exposure to salt spray;
- la figure 2 montre des micrographies d’analyse par microscopie électronique à balayage d’éprouvettes en alliage d’aluminium anodisées et colmatées conformément à l’invention, a / par une composition aqueuse contenant des ions fluorozirconate, molybdate et lithium (C1 ), b / par une composition aqueuse contenant des ions fluorozirconate, molybdate, lithium et permanganate (C2), c/ par une composition aqueuse contenant des ions fluorozirconate, molybdate, lithium et cérium (C3), d/ par une composition aqueuse contenant des ions fluorozirconate, molybdate, lithium, permanganate et cérium (C4) ; sur cette figure, pour chaque éprouvette, est représentée à gauche l’image obtenue en mode électrons rétrodiffusés et à droite l’image en mode électronique secondaire ; FIG. 2 shows analysis micrographs by scanning electron microscopy of anodized and clogged aluminum alloy test pieces in accordance with the invention, a / by an aqueous composition containing fluorozirconate, molybdate and lithium (C1) ions, b / by an aqueous composition containing fluorozirconate, molybdate, lithium and permanganate ions (C2), c / by an aqueous composition containing fluorozirconate, molybdate, lithium and cerium (C3) ions, d / by an aqueous composition containing fluorozirconate ions , molybdate, lithium, permanganate and cerium (C4); in this figure, for each test tube, the image obtained in backscattered electron mode is shown on the left and the image in secondary electronic mode on the right;
- la figure 3 montre une photographie d’une éprouvette laminée en alliage d’aluminium, anodisée et colmatée conformément à l’invention par une composition aqueuse contenant des ions fluorozirconate, molybdate, lithium, permanganate et cérium, et marquée selon un motif en X par une pointe de
Van Laar : - Figure 3 shows a photograph of a laminated test piece of aluminum alloy, anodized and sealed according to the invention with an aqueous composition containing fluorozirconate, molybdate, lithium, permanganate and cerium ions, and marked according to an X pattern by a touch of Van Laar:
- et la figure 4 montre des micrographies d’analyse par microscopie électronique à balayage d’éprouvettes en alliage d’aluminium anodisées et colmatées, et marquées selon un motif en X par une pointe de Van Laar, avant exposition au brouillard salin (a/), et après 816 h d’exposition au brouillard salin, respectivement après un colmatage par une composition aqueuse appliquée par le procédé conforme à l’invention contenant des ions fluorozirconate, molybdate, lithium, permanganate et cérium (b/) et après un colmatage par une composition aqueuse contenant uniquement des ions fluorozirconate (c/ et d/, à différents grossissements). - and Figure 4 shows scanning electron microscopy micrographs of anodized and clogged aluminum alloy specimens, and marked in an X pattern by a Van Laar point, before exposure to salt spray (a / ), and after 816 h of exposure to salt spray, respectively after clogging with an aqueous composition applied by the process according to the invention containing fluorozirconate, molybdate, lithium, permanganate and cerium (b /) ions and after clogging by an aqueous composition containing only fluorozirconate ions (c / and d /, at different magnifications).
EXEMPLE 1 EXAMPLE 1
Des éprouvettes en alliage d’aluminium AA2024 (de composition suivante : 1 ,2 à 1 ,8 % Mg, 0,3 à 0,9 % Mn, max. 0,5 % Fe, 3,8 à 4,9 % Cu, max. 0,25 % Zn, max. 0,1 % Cr, max. 0,15 % Ti, Al pour le % restant), laminé ou usiné, de dimensions 25x100x3 mm (pour les caractérisations microstructurales) et 150x80x3 mm (pour les essais au brouillard salin) ont été traitées par le procédé conforme à la présente invention selon les conditions opératoires suivantes. Les éprouvettes ont tout d’abord été soumises à des étapes de préparation de surface. A cet effet, elles ont été successivement trempées dans les bains ci-après : AA2024 aluminum alloy test pieces (of the following composition: 1.2 to 1.8% Mg, 0.3 to 0.9% Mn, max. 0.5% Fe, 3.8 to 4.9% Cu , max 0.25% Zn, max 0.1% Cr, max 0.15% Ti, Al for the remaining%), laminated or machined, dimensions 25x100x3 mm (for microstructural characterizations) and 150x80x3 mm ( for the salt spray tests) were treated by the process in accordance with the present invention according to the following operating conditions. The test pieces were first subjected to surface preparation steps. To this end, they have been successively soaked in the following baths:
- bain aqueux contenant du Turco® 4215 NCLT 50 (50 g/l) et Turco® 4215 additive pH 9 (10 g/l), à 60 °C, pendant 20 min (dégraissage alcalin) - aqueous bath containing Turco® 4215 NCLT 50 (50 g / l) and Turco® 4215 additive pH 9 (10 g / l), at 60 ° C, for 20 min (alkaline degreasing)
- eau déminéralisée à température ambiante pendant 5 min- demineralized water at room temperature for 5 min
(rinçage) (rinsing)
- bain aqueux contenant du Turco® Smut Go NC (19 % v/v), à 20 °C, pendant 5 min (décapage) - eau déminéralisée à température ambiante pendant 5 min- aqueous bath containing Turco® Smut Go NC (19% v / v), at 20 ° C, for 5 min (pickling) - demineralized water at room temperature for 5 min
(rinçage).
Les éprouvettes ont ensuite été soumises à un traitement d’oxydation anodique sulfurique, de manière classique en elle-même, selon les paramètres suivants : (rinsing). The test pieces were then subjected to an anodic sulfuric oxidation treatment, conventionally in itself, according to the following parameters:
- bain électrolytique aqueux d’acide sulfurique à 200 g/l - durée 21 ,33 min - aqueous electrolytic bath of sulfuric acid at 200 g / l - duration 21, 33 min
- température du bain 19 °C - bath temperature 19 ° C
- montée en tension à une vitesse de 3 V/min, jusqu’à une valeur plateau de 16 V, et maintien à cette valeur plateau pendant 16 min. - voltage increase at a speed of 3 V / min, up to a plateau value of 16 V, and maintenance at this plateau value for 16 min.
A l’issue de ces étapes, on a obtenu une couche anodique sur la surface des éprouvettes. At the end of these steps, an anodic layer was obtained on the surface of the test pieces.
Les éprouvettes ont ensuite été soumises à un traitement de colmatage conformément à la présente invention. Pour cela, elles ont été immergées dans la composition aqueuse suivante : The test pieces were then subjected to a sealing treatment in accordance with the present invention. For this, they were immersed in the following aqueous composition:
- K2ZrF6 25 g/l - K2ZrF6 25 g / l
- Na2Mo04, 2H2O 5 g/l - Na2Mo04, 2H2O 5 g / l
- L1NO3 4 g/l - L1NO3 4 g / l
- KMn04 9,5 g/l - KMn0 4 9.5 g / l
- Ce(N03)3, 6H2O 0,1 g/l - Ce (N0 3 ) 3 , 6H2O 0.1 g / l
Le pH de cette composition est égal à 6. The pH of this composition is 6.
Certaines éprouvettes ont été traitées par la même composition, mais dépourvue de Ce(N03)3 (« sans Ce »). Certain test pieces were treated with the same composition, but devoid of Ce (N03) 3 ("without Ce").
Les températures et durées de traitement sont indiquées dans le tableau 1 ci-après. The temperatures and treatment times are indicated in Table 1 below.
A l’issue de ces étapes, on a obtenu sur la surface des éprouvettes une couche d’épaisseur indiquée dans le tableau 1 ci-après. At the end of these steps, a layer of thickness is given on the surface of the test pieces, indicated in Table 1 below.
Après colmatage, les éprouvettes ont été directement, c’est-à-dire sans rinçage, été exposées au brouillard salin pendant 750 ou 1176 h, à une température entre 15 et 25 °C, selon les conditions conformes à la norme
NF EN ISO 9227. After clogging, the test pieces were directly, that is to say without rinsing, exposed to salt spray for 750 or 1176 h, at a temperature between 15 and 25 ° C, according to the conditions in accordance with the standard. NF EN ISO 9227.
Chaque ensemble de conditions a été réalisé en triplicat. Each set of conditions was carried out in triplicate.
A titre d’exemple comparatif, des éprouvettes ont été soumises à colmatage au moyen du procédé à base de chrome trivalent commercialisé sous la dénomination SurTec® 650. By way of comparative example, test pieces were subjected to clogging by means of the trivalent chromium-based process sold under the name SurTec® 650.
Les résultats obtenus, s’exprimant en nombres de piqûres observées sur la surface de l’éprouvette après l’exposition au brouillard salin, sont montrés dans le tableau 1 ci-après. The results obtained, expressed in numbers of pits observed on the surface of the test piece after exposure to salt spray, are shown in Table 1 below.
Tableau 1 - résultats d’un test d’exposition au brouillard salin pour des pièces en alliage d’aluminium anodisées et colmatées Table 1 - results of a salt spray exposure test for anodized and clogged aluminum alloy parts
Comme on peut le constater, on obtient pour toutes les conditions
testées une protection très satisfaisante des éprouvettes contre la corrosion. Des résultats particulièrement bons sont avantageusement obtenus pour le traitement avec cérium à température ambiante : au bout de 8 min seulement, la tenue des éprouvettes à la corrosion est particulièrement bonne, ceci tant pour les éprouvettes laminées, que pour celles qui ont été usinées dans la masse. Elle est en particulier similaire, et même meilleure pour les éprouvettes usinées, à celle obtenue par le procédé commercial SurTec® 650 à base de chrome proposé par l’art antérieur. As we can see, we obtain for all conditions tested very satisfactory protection of the test pieces against corrosion. Particularly good results are advantageously obtained for the treatment with cerium at room temperature: after only 8 min, the resistance of the test pieces to corrosion is particularly good, this as well for the rolled test pieces, as for those which have been machined in the mass. It is in particular similar, and even better for machined test pieces, to that obtained by the commercial SurTec® 650 process based on chromium proposed by the prior art.
EXEMPLE 2 EXAMPLE 2
Des éprouvettes en alliage d’aluminium AA2024, laminées, de dimensions 25x10x1 mm, ont été soumises à des étapes de préparation de surface puis d’anodisation comme décrit dans l’exemple 1 ci-avant. AA2024 aluminum alloy test pieces, laminated, of dimensions 25 × 10 × 1 mm, were subjected to steps of surface preparation and then anodization as described in Example 1 above.
Ces éprouvettes ont ensuite été colmatées au moyen des compositions appliquées par un procédé selon l’invention et décrites dans le tableau 2 (C1 à C4). These test pieces were then sealed using the compositions applied by a process according to the invention and described in Table 2 (C1 to C4).
À titre d’exemples comparatifs, des éprouvettes similaires ont été colmatées au moyen de compositions non conformes à l’invention, également décrites dans le tableau 2 (Compl et Comp2). By way of comparative examples, similar test pieces were sealed using compositions not in accordance with the invention, also described in Table 2 (Compl and Comp2).
Certaines éprouvettes n’ont subi aucun traitement de colmatage après l’anodisation (Comp). Some specimens have not undergone any clogging treatment after anodization (Comp).
Les conditions de colmatage ont été de 15 min à température ambiante (c’est-à-dire environ 21 °C). The sealing conditions were 15 min at room temperature (i.e. around 21 ° C).
A l’issue du traitement de colmatage, les éprouvettes ont été rincées à l’eau et séchées à 60 °C pendant 10 min. After the sealing treatment, the test pieces were rinsed with water and dried at 60 ° C for 10 min.
L’épaisseur de la couche qui a été formée sur leur surface est indiquée dans le tableau 2 ci-dessous. The thickness of the layer that has been formed on their surface is shown in Table 2 below.
Tableau 2 - Compositions de colmatage mises en œuvre Table 2 - Clogging compositions used
Les éprouvettes ont été soumises aux tests suivants. The test pieces were subjected to the following tests.
Test de tenue au brouillard salin Salt spray test
Ce test a été réalisé comme décrit dans l’exemple 1 ci-avant, pendant 750 h, pour les éprouvettes traitées par la composition C4 selon l’invention. This test was carried out as described in Example 1 above, for 750 h, for the test pieces treated with composition C4 according to the invention.
Après 750 h d’exposition au brouillard salin, on n’observe que très peu de piqûres de corrosion à la surface des éprouvettes, comme on peut l’observer sur les photographies montrées sur la figure 1. After 750 h of exposure to salt spray, very little corrosion pitting is observed on the surface of the test pieces, as can be seen in the photographs shown in Figure 1.
Pour ces éprouvettes, on constate en moyenne l’apparition de 3 piqûres de corrosion par dm2 après 750 h d’exposition au brouillard salin. For these test pieces, there is on average the appearance of 3 pitting corrosion per dm 2 after 750 h of exposure to salt spray.
Des résultats similaires sont obtenus pour des éprouvettes du même alliage et de mêmes dimensions, obtenues par usinage. Similar results are obtained for test pieces of the same alloy and of the same dimensions, obtained by machining.
Test électrochimique Electrochemical test
La technique mise en œuvre pour caractériser le comportement des éprouvettes traitées vis-à-vis de la corrosion est celle des courbes de polarisation. Les courbes anodique et cathodique ont été obtenues sur des échantillons différents pour chacune des compositions de colmatage étudiées. The technique used to characterize the behavior of the treated specimens with respect to corrosion is that of polarization curves. The anode and cathode curves were obtained on different samples for each of the clogging compositions studied.
A cet effet, il a été mis en œuvre une cellule thermostatée à 3 électrodes standard. Le milieu était une solution de NaCI à 0,1 M dans l’eau, pH 5,67. Les mesures ont été réalisées à 25 °C. La contre-électrode était en platine et l’électrode de référence en argent / chlorure d’argent / chlorure de potassium 3M (E(Ag/AgCI) = +0,210 V vs électrode standard à hydrogène). To this end, a thermostatically controlled cell with 3 standard electrodes has been used. The medium was a 0.1 M NaCl solution in water, pH 5.67. The measurements were carried out at 25 ° C. The counter electrode was platinum and the reference electrode was silver / silver chloride / potassium chloride 3M (E (Ag / AgCI) = +0.210 V vs standard hydrogen electrode).
Les courbes de polarisation potentiodynamiques anodique et
cathodique ont été obtenues par un potentiostat/galvanostat Gamry, avec une vitesse de balayage de potentiel de 0,5 mV/s. The anodic and potentiodynamic polarization curves cathodic were obtained by a Gamry potentiostat / galvanostat, with a potential scanning speed of 0.5 mV / s.
L'enregistrement des courbes potentiodynamiques a été réalisé à partir du potentiel du circuit ouvert (Eocp), mesuré en absence de courant externe tant dans les directions anodique que cathodique. Des échantillons individuels ont été utilisés pour chaque courbe potentiodynamique enregistrée. Le potentiel de circuit ouvert des échantillons étudiés a été établi par mesure directe de la fonction "Eocp-t" par rapport à la même électrode de référence après immersion dans la solution de NaCI 0,1 M jusqu'à 15 min. Les valeurs du courant de corrosion i¥rr ont été déterminées par extrapolation de Tafel de la région linéaire des courbes de polarisation anodiques au potentiel de corrosionThe recording of the potentiodynamic curves was carried out from the potential of the open circuit (E ocp ), measured in the absence of external current both in the anodic and cathodic directions. Individual samples were used for each potentiodynamic curve recorded. The open circuit potential of the samples studied was established by direct measurement of the "Eocp-t" function with respect to the same reference electrode after immersion in the 0.1 M NaCl solution up to 15 min. The values of the corrosion current i ¥ rr were determined by Tafel extrapolation of the linear region of the anodic polarization curves at the corrosion potential.
Ecorr. Corr.
Pour l’exemple comparatif non colmaté Comp, on a ainsi obtenu un courant de corrosion icorr = 6.108 A.cnr2. La comparaison des courbes potentiodynamiques anodique et cathodique obtenues pour les éprouvettes avant et après leur anodisation a montré que la couche anodique formée est une barrière efficace pour la réaction cathodique ainsi que pour la réaction anodique du processus de corrosion. For the non-clogged comparative example Comp, a corrosion current icorr = 6.10 8 A.cnr 2 was thus obtained. The comparison of the anodic and cathodic potentiodynamic curves obtained for the test pieces before and after their anodization has shown that the anodic layer formed is an effective barrier for the cathodic reaction as well as for the anodic reaction of the corrosion process.
Concernant les éprouvettes colmatées, les résultats obtenus sont montrés dans le tableau 3 ci-après. Concerning the clogged test pieces, the results obtained are shown in Table 3 below.
Tableau 3 - paramètres électrochimiques d’éprouvettes en alliage d’aluminium anodisées et colmatées Table 3 - electrochemical parameters of anodized and clogged aluminum alloy test pieces
SSC désigne l’électrode d’argent standard, Eœrr désigne le potentiel de corrosion et i¥rr désigne le courant de corrosion. SSC stands for the standard silver electrode, Eœrr stands for the corrosion potential and i ¥ rr stands for the corrosion current.
On constate que pour toutes les compositions appliquées par le procédé conforme à l’invention et testées, le courant de corrosion est inférieur
à celui obtenu pour l’exemple comparatif non colmaté, ainsi que pour l’exemple comparatif non conforme à l’invention Comp2. Des résultats particulièrement bons sont obtenus pour les compositions appliquées par le procédé selon l’invention C1 et C2. It is found that for all the compositions applied by the process according to the invention and tested, the corrosion current is lower to that obtained for the comparative example not clogged, as well as for the comparative example not in accordance with the invention Comp2. Particularly good results are obtained for the compositions applied by the process according to the invention C1 and C2.
Des résultats similaires sont obtenus pour des éprouvettes du même alliage et de mêmes dimensions, obtenues par usinage. Similar results are obtained for test pieces of the same alloy and of the same dimensions, obtained by machining.
Microscopie électronique à balayage (SEM) et spectroscopie à rayons X à dispersion d'énergie (EDX) Scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDX)
La morphologie, la structure et la composition de surface des éprouvettes colmatées ont été examinées par microscopie électronique à balayage (SEM) à l'aide d'un microscope électronique JEOL JSM 6390 (Japon) équipé d'un système de balayage ultra-haute résolution (ASID-3D), dans les conditions d”image électronique secondaire (SEI), et d’électrons rétrodiffusés (BEI). Le microscope électronique était équipé d'un spectromètre à dispersion d'énergie Oxford Instruments INCA x-sight, qui permet de réaliser des analyses par rayons X par microsonde EDX des échantillons étudiés en un point fixe. The morphology, structure and surface composition of the clogged specimens were examined by scanning electron microscopy (SEM) using a JEOL JSM 6390 electron microscope (Japan) equipped with an ultra-high resolution scanning system. (ASID-3D), under the conditions of secondary electronic image (SEI), and backscattered electrons (BEI). The electron microscope was equipped with an Oxford Instruments INCA x-sight energy dispersing spectrometer, which allows X-ray analyzes by EDX microprobe of the samples studied at a fixed point.
Les résultats obtenus par l’analyse EDX sont indiqués dans le tableau 4 ci-après, pour le spectre intégral, avec une amplification de x500. Pour chaque élément, la teneur est indiquée en % en poids. Il est à noter que cette technique ne permet pas de détecter la présence de lithium et de cérium dans la couche superficielle de la pièce. The results obtained by the EDX analysis are shown in Table 4 below, for the full spectrum, with an amplification of x500. For each element, the content is indicated in% by weight. It should be noted that this technique does not make it possible to detect the presence of lithium and cerium in the surface layer of the part.
Tableau 4 - Analyse EDX d’éprouvettes en alliage d’aluminium anodisées et colmatées Table 4 - EDX analysis of anodized and clogged aluminum alloy test pieces
nd indique un élément présent mais de quantité non déterminée nd indicates an element present but of quantity not determined
La figure 2 montre les micrographies obtenues par SEM pour les éprouvettes traitées avec les compositions appliquées par le procédé conforme à l’invention C1 (en a/), C2 (en b/), C3 (en c/) et C4 (en d/). FIG. 2 shows the micrographs obtained by SEM for the test specimens treated with the compositions applied by the method according to the invention C1 (in a /), C2 (in b /), C3 (in c /) and C4 (in d /).
Comme on peut le voir, l’éprouvette traitée avec la composition C1 (a/) est caractérisée par une couche de surface dense avec une structure sphéroïdale symétriquement ordonnée. L'analyse intégrale à partir d'une surface "large" a établi la présence de zirconium, fluor et molybdène. As can be seen, the test tube treated with composition C1 (a /) is characterized by a dense surface layer with a symmetrically ordered spheroidal structure. Integral analysis from a "large" surface established the presence of zirconium, fluorine and molybdenum.
L’éprouvette traitée avec la composition C2 (b/) est recouverte d'une couche de surface dense. Elle contient également des agglomérats sphéroïdaux uniformes contenant notamment du zirconium, du fluor, du manganèse et du molybdène. The specimen treated with composition C2 (b /) is covered with a dense surface layer. It also contains uniform spheroidal agglomerates containing in particular zirconium, fluorine, manganese and molybdenum.
L’éprouvette traitée avec la composition C3 (c/) est elle aussi recouverte d'une couche dense d'agglomérats sphéroïdaux de deux ordres de taille différents, et de composition chimique différente. L'analyse EDX intégrale d'une surface « large » a notamment établi la présence de zirconium, fluor et molybdène. The test tube treated with composition C3 (c /) is also covered with a dense layer of spheroidal agglomerates of two orders of different size, and of different chemical composition. The integral EDX analysis of a "large" surface has notably established the presence of zirconium, fluorine and molybdenum.
Pour l’éprouvette traitée avec la composition C4 (d/), la morphologie de surface est également une couche de surface dense contenant des agglomérats sphéroïdaux, et contenant notamment du zirconium, du fluor, du manganèse et du molybdène. For the test piece treated with composition C4 (d /), the surface morphology is also a dense surface layer containing spheroidal agglomerates, and containing in particular zirconium, fluorine, manganese and molybdenum.
Des résultats similaires sont obtenus pour des éprouvettes du même alliage et de mêmes dimensions, obtenues par usinage. Similar results are obtained for test pieces of the same alloy and of the same dimensions, obtained by machining.
EXEMPLE 3 EXAMPLE 3
Des éprouvettes laminées en alliage d’aluminium AA2024, de dimensions 150x80x3 mm ont été traitées par le procédé conforme à la présente invention décrit dans l’exemple 1 ci-dessus, mais avec la composition aqueuse selon l’invention suivante :
- K2ZrF6 12 g/l Laminated test pieces of aluminum alloy AA2024, of dimensions 150 × 80 × 3 mm were treated by the process in accordance with the present invention described in example 1 above, but with the aqueous composition according to the following invention: - K 2 ZrF 6 12 g / l
- Na2Mo04, 2H20 10 g/l - Na 2 Mo04, 2H 2 0 10 g / l
- LiNOs 8 g/l - LiNOs 8 g / l
- KMn04 19 g/l - KMn0 4 19 g / l
- Ce(N03)3, 6H20 0,2 g/l - Ce (N0 3 ) 3,6H 2 0 0,2 g / l
Le pH de cette composition est de 5,82 (mesuré à 19,9 °C). The pH of this composition is 5.82 (measured at 19.9 ° C).
Les conditions de traitement avec cette composition sont les suivantes : 19 °C, 15 min. The treatment conditions with this composition are as follows: 19 ° C, 15 min.
A l’issue du traitement, après un rinçage à l’eau et un séchage à 60 °C, les éprouvettes sont marquées, selon un motif en X, conformément à la norme ISO 17872, au moyen d’une pointe de Van Laar en carbure de tungstène. Les marques sont réalisées en profondeur, de sorte à pénétrer entièrement la couche de surface, jusqu’à atteindre l’alliage métallique de base constituant l’éprouvette. At the end of the treatment, after rinsing with water and drying at 60 ° C., the test pieces are marked, according to an X pattern, in accordance with standard ISO 17872, by means of a Van Laar point in tungsten carbonate. The marks are made in depth, so as to completely penetrate the surface layer, until reaching the basic metal alloy constituting the test piece.
Une photographie d’une éprouvette ainsi marquée est montrée sur la figure 3. La figure 4 montre, en a/, une micrographie d’analyse par microscopie électronique à balayage d’une zone marquée. A photograph of a specimen thus marked is shown in FIG. 3. FIG. 4 shows, in a /, an analysis micrograph by scanning electron microscopy of a marked area.
A titre comparatif, il est également réalisé des éprouvettes marquées après anodisation et traitement de colmatage au moyen d’une composition aqueuse contenant uniquement du K2ZrF6 à la concentration de 12 g/l. By way of comparison, marked test tubes are also produced after anodization and clogging treatment using an aqueous composition containing only K 2 ZrF6 at a concentration of 12 g / l.
Les éprouvettes ainsi marquées sont soumises à un test d’exposition au brouillard salin pendant 816 h, à une température entre 15 et 25 °C, selon les conditions conformes à la norme NF EN ISO 9227. The specimens thus marked are subjected to a salt spray exposure test for 816 h, at a temperature between 15 and 25 ° C, according to the conditions in accordance with standard NF EN ISO 9227.
Les résultats obtenus, pour chaque condition testée, sont montrés sur la figure 4, en b / pour une éprouvette traitée au moyen de la composition appliquée par le procédé selon l’invention, et en c/ et d/, à différents grossissements, pour une éprouvette traitée par la composition comparative contenant uniquement de l’hexafluorozirconate de potassium. The results obtained, for each condition tested, are shown in FIG. 4, in b / for a test piece treated using the composition applied by the method according to the invention, and in c / and d /, at different magnifications, for a test tube treated with the comparative composition containing only potassium hexafluorozirconate.
Comme on peut le constater sur cette figure, à l’issue du test d’exposition au brouillard salin, on observe pour l’éprouvette traitée par la
composition comparative, contenant uniquement de l’hexafluorozirconate de potassium, des piqûres de corrosion dans les marques formées sur l’éprouvette (dont des exemples sont indiqués par un encadrement en c/ et d/ sur la figure). Au contraire, on n’observe aucune piqûre de corrosion pour l’éprouvette traitée conformément à la présente invention, et des défauts occasionnés par le marquage ont même été réparés. Ceci démontre clairement l’efficacité de la composition mise en œuvre par le procédé selon l’invention pour la protection des pièces contre la corrosion, et un effet auto-cicatrisant de cette composition : les défauts induits sur la surface de la pièce sont avantageusement efficacement réparés. As can be seen in this figure, at the end of the salt spray exposure test, we observe for the test specimen treated by the comparative composition, containing only potassium hexafluorozirconate, pitting corrosion in the marks formed on the test piece (examples of which are indicated by a box in c / and d / in the figure). On the contrary, no corrosion pitting was observed for the specimen treated in accordance with the present invention, and defects caused by the marking were even repaired. This clearly demonstrates the effectiveness of the composition used by the method according to the invention for protecting the parts against corrosion, and a self-healing effect of this composition: the defects induced on the surface of the part are advantageously effectively repaired.
Des résultats similaires sont obtenus pour des éprouvettes du même alliage et de mêmes dimensions, obtenues par usinage.
Similar results are obtained for test pieces of the same alloy and of the same dimensions, obtained by machining.
Claims
1. Procédé de traitement de surface d’une pièce en aluminium ou alliage d’aluminium ou en magnésium ou alliage de magnésium, caractérisé en ce qu’il comprend : 1. A method of surface treatment of an aluminum or aluminum alloy or magnesium or magnesium alloy part, characterized in that it comprises:
- une étape de traitement par oxydation de ladite pièce, a step of treatment by oxidation of said part,
- une étape d’application sur la surface de ladite pièce d’une composition aqueuse exempte de chrome et contenant : an application step on the surface of said part of an aqueous composition free of chromium and containing:
- des ions fluorozirconate, - fluorozirconate ions,
- des ions molybdate, - molybdate ions,
- et au moins un composant choisi parmi les ions lithium et les ions permanganate. - And at least one component chosen from lithium ions and permanganate ions.
2. Procédé selon la revendication 1 , caractérisé en ce que ladite étape de traitement par oxydation de ladite pièce est une étape de traitement par anodisation. 2. Method according to claim 1, characterized in that said step of treatment by oxidation of said part is a step of treatment by anodization.
3. Procédé selon l’une quelconque des revendications 1 ou 2, caractérisé en ce que ladite étape de traitement par oxydation de ladite pièce est une étape d’oxydation micro-arc. 3. Method according to any one of claims 1 or 2, characterized in that said oxidation treatment step of said part is a micro-arc oxidation step.
4. Procédé selon l’une quelconque des revendications 1 à 3, caractérisé en ce que ladite étape d’application est réalisée par immersion de ladite pièce dans un bain de ladite composition aqueuse. 4. Method according to any one of claims 1 to 3, characterized in that said application step is carried out by immersion of said part in a bath of said aqueous composition.
5. Procédé selon l’une quelconque des revendications 1 à 4, caractérisé en ce que ladite composition aqueuse appliquée lors de l’étape d’application présente une température comprise entre 10 et 60 °C. 5. Method according to any one of claims 1 to 4, characterized in that said aqueous composition applied during the application step has a temperature between 10 and 60 ° C.
6. Procédé selon l’une quelconque des revendications 1 à 5, caractérisé en ce que ladite application est réalisée pendant un temps supérieur ou égal à 5 minutes, de préférence compris entre 5 et 20 minutes.
6. Method according to any one of claims 1 to 5, characterized in that said application is carried out for a time greater than or equal to 5 minutes, preferably between 5 and 20 minutes.
7. Procédé selon l’une quelconque des revendications 1 à 6, comprenant en outre une étape préalable de prétraitement de ladite pièce par dégraissage et/ou décapage chimiques. 7. Method according to any one of claims 1 to 6, further comprising a preliminary step of pretreatment of said part by degreasing and / or chemical pickling.
8. Procédé selon l’une des revendications 1 à 7, caractérisé en ce que ladite composition aqueuse contient des ions lithium et des ions permanganate. 8. Method according to one of claims 1 to 7, characterized in that said aqueous composition contains lithium ions and permanganate ions.
9. Procédé selon l’une quelconque des revendications 1 à 8, caractérisé en ce que ladite composition aqueuse contient des ions cérium. 9. Method according to any one of claims 1 to 8, characterized in that said aqueous composition contains cerium ions.
10. Procédé selon l’une quelconque des revendications 1 à 9, caractérisé en ce que ladite composition aqueuse contient des ions nitrate. 10. Method according to any one of claims 1 to 9, characterized in that said aqueous composition contains nitrate ions.
11. Procédé selon la revendication 10, caractérisé en ce que ladite composition aqueuse contient du nitrate de lithium. 11. Method according to claim 10, characterized in that said aqueous composition contains lithium nitrate.
12. Procédé selon l’une quelconque des revendications 1 à 11 , caractérisé en ce que ladite composition aqueuse présente un pH compris entre 3 et 7. 12. Method according to any one of claims 1 to 11, characterized in that said aqueous composition has a pH between 3 and 7.
13. Procédé selon l’une quelconque des revendications 1 à 12, caractérisé en ce que ladite composition aqueuse contient au moins une des concentrations suivantes : 13. Method according to any one of claims 1 to 12, characterized in that said aqueous composition contains at least one of the following concentrations:
- entre 5 et 30 g/l de sel de fluorozirconate, - between 5 and 30 g / l of fluorozirconate salt,
- entre 2,5 et 10 g/l de sel de molybdate, - between 2.5 and 10 g / l of molybdate salt,
- entre 2 et 8 g/l de sel de lithium, - between 2 and 8 g / l of lithium salt,
- entre 4 et 19 g/l de sel de permanganate, - between 4 and 19 g / l of permanganate salt,
- et/ou, entre 0,1 et 0,5 g/l de sel de cérium. - And / or, between 0.1 and 0.5 g / l of cerium salt.
14. Pièce en aluminium ou alliage d’aluminium ou en magnésium ou alliage de magnésium obtenue par un procédé selon l’une quelconque des revendications 1 à 13.
14. Part made of aluminum or aluminum alloy or magnesium or magnesium alloy obtained by a process according to any one of claims 1 to 13.
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|---|---|---|---|
| FR1855209A FR3082528B1 (en) | 2018-06-14 | 2018-06-14 | AQUEOUS COMPOSITION AND PROCESS FOR SURFACE TREATMENT OF AN ALUMINUM ALLOY PART USING SUCH A COMPOSITION |
| PCT/FR2019/051449 WO2019239077A1 (en) | 2018-06-14 | 2019-06-14 | Process for treating the surface of a part made of aluminium or aluminium alloy or of magnesium or magnesium alloy |
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| EP (1) | EP3810833A1 (en) |
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| CN115558914A (en) * | 2022-02-16 | 2023-01-03 | 深圳市尚笠实业有限公司 | Aluminum-based metal material surface protective agent and preparation method thereof |
| CN115386936A (en) * | 2022-08-26 | 2022-11-25 | 长春理工大学 | Method for preparing 7075 aluminum alloy black antireflection coating based on micro-arc oxidation |
| FR3140382A1 (en) * | 2022-10-04 | 2024-04-05 | Safran Landing Systems | PROCESS FOR POST-ANODIZATION SEALING OF ALUMINUM AND ALUMINUM ALLOYS WITHOUT USING CHROME |
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| US6669786B2 (en) | 1997-06-27 | 2003-12-30 | Concurrent Technologies Corporation | Self-healing non-chromate coatings for aluminum and aluminum alloys |
| DE10358310A1 (en) * | 2003-12-11 | 2005-07-21 | Henkel Kgaa | Two-stage conversion treatment |
| GB2469115B (en) * | 2009-04-03 | 2013-08-21 | Keronite Internat Ltd | Process for the enhanced corrosion protection of valve metals |
| FR2986807B1 (en) | 2012-02-10 | 2015-05-15 | Mecaprotec Ind | PROCESS FOR ANODIZING ALUMINUM ALLOY PARTS |
| RU2611610C2 (en) * | 2012-08-29 | 2017-02-28 | Ппг Индастриз Огайо, Инк. | Zirconium pretreatment compositions containing molybdenum, associated methods for treating metal substrates, and related coated metal substrates |
| CN104294257A (en) * | 2013-07-19 | 2015-01-21 | 无锡永发电镀有限公司 | Technology for passivating aluminum alloy pieces applied to automobiles |
| AU2016210539B2 (en) * | 2015-01-19 | 2020-10-08 | Council Of Scientific And Industrial Research | A process for the preparation of corrosion resistant sealed anodized coatings on aluminum alloy |
| CA3032158A1 (en) * | 2016-08-12 | 2018-02-15 | Prc-Desoto International, Inc. | Systems and methods for treating a metal substrate through thin film pretreatment and a sealing composition |
| CN109440163B (en) * | 2018-12-28 | 2022-02-22 | 江苏飞拓界面工程科技有限公司 | Nickel-free hole sealing agent for aluminum and aluminum alloy anodic oxide films and application thereof |
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| FR3082528A1 (en) | 2019-12-20 |
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