EP3464681A1 - Procede de chromatation et piece obtenue par ce procede - Google Patents
Procede de chromatation et piece obtenue par ce procedeInfo
- Publication number
- EP3464681A1 EP3464681A1 EP17732979.4A EP17732979A EP3464681A1 EP 3464681 A1 EP3464681 A1 EP 3464681A1 EP 17732979 A EP17732979 A EP 17732979A EP 3464681 A1 EP3464681 A1 EP 3464681A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- chromating
- aluminum
- layer
- coating
- aluminum oxide
- 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.)
- Withdrawn
Links
- 238000004532 chromating Methods 0.000 title claims abstract description 52
- 238000000034 method Methods 0.000 title claims abstract description 25
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 40
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 37
- 229910045601 alloy Inorganic materials 0.000 claims abstract description 30
- 239000000956 alloy Substances 0.000 claims abstract description 30
- 239000000126 substance Substances 0.000 claims abstract description 27
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims abstract description 25
- 238000006243 chemical reaction Methods 0.000 claims abstract description 17
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 claims description 74
- 238000000576 coating method Methods 0.000 claims description 64
- 239000011248 coating agent Substances 0.000 claims description 62
- 239000011651 chromium Substances 0.000 claims description 27
- 229910052804 chromium Inorganic materials 0.000 claims description 24
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 claims description 12
- 229910052726 zirconium Inorganic materials 0.000 claims description 12
- 238000007654 immersion Methods 0.000 claims description 11
- 239000002245 particle Substances 0.000 claims description 11
- 238000010297 mechanical methods and process Methods 0.000 claims description 9
- 230000005226 mechanical processes and functions Effects 0.000 claims description 8
- 239000007787 solid Substances 0.000 claims description 8
- 238000005011 time of flight secondary ion mass spectroscopy Methods 0.000 claims description 7
- 238000001311 chemical methods and process Methods 0.000 claims description 6
- 238000006056 electrooxidation reaction Methods 0.000 claims description 3
- 239000007788 liquid Substances 0.000 claims description 3
- PNEYBMLMFCGWSK-UHFFFAOYSA-N Alumina Chemical compound [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 abstract description 8
- 239000004411 aluminium Substances 0.000 abstract 1
- 238000005260 corrosion Methods 0.000 description 14
- 230000007797 corrosion Effects 0.000 description 14
- 239000000243 solution Substances 0.000 description 13
- 229910000838 Al alloy Inorganic materials 0.000 description 11
- 230000015572 biosynthetic process Effects 0.000 description 7
- 239000000203 mixture Substances 0.000 description 7
- JOPOVCBBYLSVDA-UHFFFAOYSA-N chromium(6+) Chemical compound [Cr+6] JOPOVCBBYLSVDA-UHFFFAOYSA-N 0.000 description 5
- 230000003628 erosive effect Effects 0.000 description 5
- 239000012530 fluid Substances 0.000 description 5
- 238000003486 chemical etching Methods 0.000 description 4
- 238000005238 degreasing Methods 0.000 description 4
- 238000004949 mass spectrometry Methods 0.000 description 4
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 3
- 238000005299 abrasion Methods 0.000 description 3
- 239000011324 bead Substances 0.000 description 3
- 150000003839 salts Chemical class 0.000 description 3
- 239000002904 solvent Substances 0.000 description 3
- 239000007921 spray Substances 0.000 description 3
- CYTYCFOTNPOANT-UHFFFAOYSA-N Perchloroethylene Chemical group ClC(Cl)=C(Cl)Cl CYTYCFOTNPOANT-UHFFFAOYSA-N 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 2
- 239000003929 acidic solution Substances 0.000 description 2
- 230000002378 acidificating effect Effects 0.000 description 2
- 239000012670 alkaline solution Substances 0.000 description 2
- LXMQZGGLHVSEBA-UHFFFAOYSA-N chromium;trihydrate Chemical compound O.O.O.[Cr] LXMQZGGLHVSEBA-UHFFFAOYSA-N 0.000 description 2
- 150000002500 ions Chemical group 0.000 description 2
- 238000003754 machining Methods 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- RVTZCBVAJQQJTK-UHFFFAOYSA-N oxygen(2-);zirconium(4+) Chemical compound [O-2].[O-2].[Zr+4] RVTZCBVAJQQJTK-UHFFFAOYSA-N 0.000 description 2
- 238000002161 passivation Methods 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 229950011008 tetrachloroethylene Drugs 0.000 description 2
- 229910001928 zirconium oxide Inorganic materials 0.000 description 2
- IRPGOXJVTQTAAN-UHFFFAOYSA-N 2,2,3,3,3-pentafluoropropanal Chemical compound FC(F)(F)C(F)(F)C=O IRPGOXJVTQTAAN-UHFFFAOYSA-N 0.000 description 1
- 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 1
- 229910018085 Al-F Inorganic materials 0.000 description 1
- KLZUFWVZNOTSEM-UHFFFAOYSA-K Aluminum fluoride Inorganic materials F[Al](F)F KLZUFWVZNOTSEM-UHFFFAOYSA-K 0.000 description 1
- 229910018179 Al—F Inorganic materials 0.000 description 1
- -1 aluminum oxy-hydroxides Chemical class 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 238000013475 authorization Methods 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- NEHMKBQYUWJMIP-UHFFFAOYSA-N chloromethane Chemical compound ClC NEHMKBQYUWJMIP-UHFFFAOYSA-N 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 229910052593 corundum Inorganic materials 0.000 description 1
- NINOVVRCHXVOKB-UHFFFAOYSA-N dialuminum;dioxido(dioxo)chromium Chemical class [Al+3].[Al+3].[O-][Cr]([O-])(=O)=O.[O-][Cr]([O-])(=O)=O.[O-][Cr]([O-])(=O)=O NINOVVRCHXVOKB-UHFFFAOYSA-N 0.000 description 1
- QDOXWKRWXJOMAK-UHFFFAOYSA-N dichromium trioxide Chemical compound O=[Cr]O[Cr]=O QDOXWKRWXJOMAK-UHFFFAOYSA-N 0.000 description 1
- KSYURTCLCUKLSF-UHFFFAOYSA-H disodium;hexafluorozirconium(2-) Chemical compound [F-].[F-].[F-].[F-].[F-].[F-].[Na+].[Na+].[Zr+4] KSYURTCLCUKLSF-UHFFFAOYSA-H 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- 150000002170 ethers Chemical class 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 229910052746 lanthanum Inorganic materials 0.000 description 1
- FZLIPJUXYLNCLC-UHFFFAOYSA-N lanthanum atom Chemical compound [La] FZLIPJUXYLNCLC-UHFFFAOYSA-N 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 230000003472 neutralizing effect Effects 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 239000003973 paint Substances 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 238000005488 sandblasting Methods 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 238000002604 ultrasonography Methods 0.000 description 1
- 239000012808 vapor phase Substances 0.000 description 1
- 229910001845 yogo sapphire Inorganic materials 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
- C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
- C23C22/34—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing fluorides or complex fluorides
-
- 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
- C23C22/78—Pretreatment of the material to be coated
-
- 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
- C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C8/02—Pretreatment of the material to be coated
-
- 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
- C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
- C23C8/08—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases only one element being applied
- C23C8/10—Oxidising
- C23C8/16—Oxidising using oxygen-containing compounds, e.g. water, carbon dioxide
-
- 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
- C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C8/80—After-treatment
-
- 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
- C23C2222/00—Aspects relating to chemical surface treatment of metallic material by reaction of the surface with a reactive medium
- C23C2222/10—Use of solutions containing trivalent chromium but free of hexavalent chromium
Definitions
- the present disclosure relates to the protection against corrosion of a part comprising an aluminum-based alloy.
- the alloys based on aluminum have the advantage of being light. However, they may be susceptible to corrosion. Also, it is known to protect parts made from aluminum alloys against corrosion by performing, for example, a chemical conversion of the surface of the workpiece.
- This chemical conversion treatment is generally carried out by putting the piece in contact with a bath containing hexavalent chromium (or chromium VI or Cr VI).
- the bath can be made from a solution such as the solution commonly known by the trademark Henkel Alodine® 1200S.
- This chemical conversion treatment is a chromating treatment of the aluminum-based alloy in which the alloy is converted to surface in order to precipitate aluminum oxy-hydroxides and aluminum chromates.
- This treatment makes it possible to produce on the surface of the part a coating which increases the resistance to corrosion as well as the wear resistance of the part made of aluminum-based alloy. Moreover, this coating makes it possible to maintain electrical conductivity of the coated zone and to allow easy and good quality adhesion of organic paints.
- the aluminum-based alloys which are exposed to air oxidize and form, on the surface of the room, a passivation layer of aluminum oxide (Al 2 O 3 ), also called alumina.
- This layer of aluminum oxide that naturally forms on the surface of the part is called a native oxide layer.
- the surface of the part is stripped in order to remove this passivation layer and to expose the aluminum-based alloy.
- This stripping makes it possible to put in contact the aluminum-based alloy and the solution comprising hexavalent chromium and thus to perform the chromium reaction of the part.
- An alternative treatment proposes to use, in place of the solution comprising hexavalent chromium, a solution comprising trivalent chromium (or chromium III or Cr III).
- a solution comprising trivalent chromium or chromium III or Cr III.
- Chromatization process means a chemical conversion process of a metal part by immersion of the workpiece in a chromating bath and performing a chemical conversion of the workpiece in the chromating bath, the chromating bath comprising chromium, in the form of chromium VI or in the form of chromium III, for example.
- the present disclosure aims to remedy at least in part these drawbacks.
- the present disclosure relates to a method of chromating a workpiece comprising an aluminum-based alloy comprising the following steps:
- the part comprising on at least one surface of the part a layer based on aluminum oxide whose thickness is greater than or equal to 5 nm;
- the formed coating has good resistance to corrosion. corrosion, especially salt spray.
- This layer based on aluminum oxide makes it possible to satisfactorily grow, on the surface of the part, a coating comprising chromium III and having desired anticorrosion properties.
- this chromating process instead of wanting to expose the aluminum-based alloy before immersion in the chromating bath, as taught by all chromating processes, seeks to promote the presence of an oxide layer on the part before it is immersed in the chromating bath. It is therefore clear that the chromating bath does not include products for dissolving the aluminum oxide layer, as can be the case in conventional methods.
- aluminum-based alloy an alloy whose average mass content of aluminum is predominant. It is understood that aluminum is the element whose mass content in the alloy is the highest.
- the aluminum-based alloy has, for example, a mass content of at least 50% aluminum, preferably at least 70% aluminum, even more preferably at least 80% aluminum.
- layer based on aluminum oxide is meant a layer whose average mass content of aluminum oxide is predominant. It is understood that aluminum oxide is the compound whose mass content in the layer is the highest.
- the aluminum oxide-based layer has, for example, a mass content of at least 30% of aluminum oxide, preferably at least 40% of aluminum oxide, even more preferably at least 50% of aluminum oxide. aluminum oxide.
- the chromating bath may comprise zirconium.
- zirconium in the chromating bath for example in the form of hexafluorozirconate, for example sodium hexafluorozirconate or potassium hexafluorozirconate, used to activate the chemical conversion reaction, forming in particular an Al-F complex with the aluminum at the interface between the part and the coating, the zirconium dissolved in solution then being deposited by reduction together with the chromium and forming a co-deposition of chromium III oxide and zirconium oxide.
- the aluminum oxide-based layer may be a native oxide layer and the part and the aluminum oxide-based layer may be degreased before immersion in the chromating bath.
- the workpiece is generally machined to give it a shape close to the finished form.
- This machining operation is performed in the presence of a machining fluid, generally an oily fluid.
- a machining fluid generally an oily fluid.
- oily fluid Despite the presence of oily fluid on the part, a layer of native oxide forms on the surface of the piece. Indeed, this fluid allows oxidation of the aluminum-based alloy. The removal of this oily fluid is achieved by degreasing the part.
- the part and the aluminum oxide-based layer can be degreased with an aqueous solution and neutral for example.
- This degreasing can be assisted by a method for generating ultrasound or cavitation.
- This degreasing operation is performed so that the native oxide layer is retained on the workpiece.
- the thickness of this native oxide layer may be greater than 5 nm, preferably greater than 10 nm, even more preferably greater than 15 nm, and less than 130 nm, preferably less than 120 nm, even more preferably lower. at 110 nm.
- the aluminum oxide-based layer may be formed by a mechanical process.
- the mechanical process may comprise a step of projecting solid particles onto the surface of the part.
- the native oxide layer is removed and the aluminum-based alloy is exposed.
- This bare aluminum alloy is very reactive and a new layer of aluminum oxide is formed on all surfaces of the part on which the solid particles have been projected. This process is also known as "sanding".
- the solid particles may be glass beads, for example silica beads, or ceramic balls, for example zirconia beads.
- the mechanical process may comprise a step of abrasion of the surface of the workpiece with abrasive paper or a liquid containing abrasive particles.
- the aluminum oxide-based layer is formed by a chemical process comprising a first step of etching the surface of the part followed by a chemical or electrochemical oxidation step of the workpiece surface.
- this chemical process it is possible to treat parts with complex geometry. Indeed, this chemical process uses solutions in liquid form which makes it possible to reach surfaces that could be difficult to reach by projection of solid particles or by abrasion.
- the chemical etching step may be carried out by spraying the part and the native oxide layer with an acidic or alkaline solution chemical solution. It is thus possible to dissolve the oxides present on the surface of the part. The piece is then dried. This chemical etching step may also be performed by immersing the part and the native oxide layer in an acidic or alkaline solution chemical solution.
- This chemical etching step may be followed by a step of neutralizing the surface of the part before drying.
- the chemical etching step is followed by a chemical or electrochemical oxidation step in order to promote the formation of the new layer based on aluminum oxide, for example by immersing the piece in a bath for a period of time. a time interval of 1 to 30 minutes.
- the layer based on aluminum oxide may be porous.
- the contact surface between the aluminum oxide layer and the chromating bath is greater than if the aluminum oxide-based layer is dense. This therefore facilitates the chromating process and increases its efficiency.
- the aluminum oxide-based layer can be obtained by arranging the part in an atmosphere comprising between 30% to 100% humidity and / or the temperature of which is between 30 ° C. and 200 ° C., example during a time interval ranging from 5 minutes to 8 hours.
- the humidity and / or the temperature can help promote the formation of the layer. based on aluminum oxide.
- the present disclosure also relates to a part comprising an aluminum-based alloy having, on at least one surface of the part, a coating comprising chromium III, the coating comprising a free surface and having a given thickness, in which in a layer of the coating between 15 and 30% of the given thickness of the coating measured from the free surface, the intensity in arbitrary units measured by TOF-SIMS in aluminum oxide varies at most by more or less 50%, preferably of plus or minus 40%, even more preferably of plus or minus 30%.
- the intensity in arbitrary units is proportional to the concentration of alumina (molar or mass).
- concentration of alumina molecular weight
- This small variation in the content of aluminum oxide close to the free surface of the coating makes it possible to determine that the aluminum oxide content of the coating very rapidly reaches a high value, close to the maximum content of oxide of aluminum. aluminum in the coating.
- This high content of aluminum oxide close to the free surface of the coating is a trace of the aluminum oxide layer present on the part before immersion of the part in the chromating bath.
- the thickness of the coating can be determined experimentally by determining the metallic aluminum content of the workpiece starting from the free surface of the workpiece. When the metal aluminum content is constant, it is considered that it is no longer in the coating but in the aluminum-based alloy.
- TOF-SIMS is a mass spectrometry analysis of secondary ions in flight time, called TOF-SIMS according to the acronym for "Time Of Flight - Seconda ry-Ions Mass Spectrometry".
- the coating may comprise chromium III in the form of chromium oxide (Cr 2 O 3 ) or chromium hydroxide (Cr (OH) 3 ), for example.
- the coating comprising chromium III may comprise zirconium.
- FIG. 1 is a partial schematic sectional view of an aluminum alloy part comprising on at least one surface of the part a layer based on aluminum oxide;
- FIG. 2 is a schematic sectional view of a chromating device
- FIG. 3 is a partial schematic sectional view of the part of FIG. 1 after completion of the chromating process
- FIGS. 4 and 5 are graphical representations of the evolution of the chemical composition of a coating as a function of the thickness of the coating;
- FIG. 1 represents a piece 10 made of alloy based on aluminum.
- This part 10 comprises on at least one surface of the part 10 a layer based on aluminum oxide 12.
- the part 10 and the layer based on aluminum oxide 12 form an oxidized part 14.
- This aluminum oxide layer 12 may be a native oxide layer, formed naturally on the surface of the aluminum-based alloy part. This aluminum oxide layer 12 may also have been formed by a mechanical process or a chemical process.
- FIG. 2 represents the step of immersing the oxidized part 114 in a tank 16 comprising the chromating bath 18 comprising chromium III.
- This chromating bath 18 may also comprise zirconium.
- a part 10 is obtained comprising on at least one surface of the part 10 a coating 20 comprising chromium III, for example in oxide form. chromium (Cr 2 O 3 ) and chromium hydroxide (Cr (OH) 3).
- the coating 20 also comprises hard zirconium in the form of zirconium oxide (Zr0 2 ). The part 10 and the coating 20 form a coated part 22 having a free surface 24 of the coating 20.
- the chromating bath 18 may for example be made from a solution commonly referred to by SurTec trademark SurTec® 650 or Lanthanum 613.3 Coventya.
- the layer based on aluminum oxide 12 may have a thickness greater than 5 nm, preferably greater than 10 nm, even more preferably greater than 15 nm, and less than 130 nm, preferably less than 120 nm, still more preferably less than 110 nm.
- This aluminum oxide-based layer 12 may be the native oxide layer or a new aluminum oxide layer obtained by a mechanical process or a chemical process.
- this aluminum oxide-based oxide layer 12 on the surface of the aluminum alloy part 10 before immersion in the chromating bath 18, after chemical conversion, it is obtained.
- a coated part 22 whose coating 20 has a good resistance to corrosion, including salt spray.
- the piece 10 Take an aluminum alloy piece 10, for example the grade 7175.
- the piece 10 is machined and then, on the piece 10 is formed a layer based on aluminum oxide 12 of which thickness is between 5-15 nm.
- the oxidized part 14 is degreased, for example using perchlorethylene under vacuum in the vapor phase. Then, the oxidized part 14 and degreased is immersed in a chromating bath 18 comprising chromium III and zirconium. After chemical conversion, a coated part 22 is obtained comprising the aluminum alloy piece 10 and a coating 20.
- the workpiece 10 is machined and then, on the workpiece 10 is formed a layer based on aluminum oxide 12 of which thickness is between 5-20 nm.
- the oxidized part 14 is then sandblasted, that is to say that solid particles are sprayed onto the surface of the oxidized part 14 so as to remove the native oxide layer and expose the alloy-based aluminum.
- This aluminum-based alloy which has just been exposed is very reactive and a new layer of aluminum oxide 14 is formed on all the surfaces of the part 10 on which the solid particles have been projected.
- the oxidized part 14 and degreased is immersed in a chromating bath 18 comprising chromium III and zirconium. After chemical conversion, we obtain a coated part 22 comprising the aluminum alloy piece 10 and a coating 20.
- the piece 10 is machined and then, on the piece 10 is formed a layer based on aluminum oxide 12 of which thickness is between 5-20 nm.
- the oxidized part 14 is degreased, for example by alkaline degreasing using a solution commonly known under the name Sococlean, for 6 minutes at 45 ° C., and then etched chemically using a solution commonly referred to as the name Socosurf, for 15 minutes at 31 ° C, so that the native oxide layer is removed and the aluminum-based alloy is exposed.
- the part 10 is then rapidly immersed in chromating bath 18 comprising chromium III and zirconium, in order to limit the formation of a new layer based on aluminum oxide, the layer based on aluminum oxide can be formed is strictly less than 5 nm.
- chromating bath 18 comprising chromium III and zirconium
- a coated part 22 is obtained comprising the aluminum alloy piece 10 and a coating 20.
- FIG. 4 shows the evolution of the chemical composition of the coated part 22 of Example 1 as a function of the distance with respect to the free surface 24, that is to say as a function of the thickness of the coating.
- FIG. 5 is a graphical representation similar to that of FIG. 4 for example 3.
- FIGS. 4 and 5 The results of Figures 4 and 5 were obtained by a mass spectrometry analysis of secondary ions in flight time, called TOF-SIMS according to the acronym for "Time Of Flight - Secondary-Ions Mass Spectrometry".
- the graphs of FIGS. 4 and 5 have the abscissa "T”, ie the erosion time in seconds (s), and the ordinate the molecular composition of the workpiece in logarithmic scale, ie a number of measured strokes "C" in units arbitrary.
- the erosion time is proportional to the distance from the free surface 24 of the coating 20. Also, at a given time, corresponds a distance from the free surface 24 of the coating 20 and a composition of the coating at this distance.
- the chemical conversion is a process for converting the surface of the part, there is no straightforward interface between the body of the piece 10 made of aluminum-based alloy and the coating 20. from the coating 20 to the aluminum-based alloy when the content of aluminum metal (Al) is relatively constant.
- the thickness of the coating 20 corresponds to a distance from the free surface 24 of the coating 20 equivalent to about 200 seconds of erosion time and about 300 seconds of erosion time, respectively for Figures 4 and 5.
- the thickness of the coating 20 is determined by the crossing curves for alumina oxide (Al 2 O 3 ) and aluminum metal (Al).
- the coating 20 having a thickness corresponding to about 200 seconds (see Figure 4), the layer between 15% and 30% of the coating, measured from the free surface 24 of the coating is therefore the numbers of shots measured between 30 and 60 seconds. Between 30 and 60 seconds, the number of strokes measured for aluminum oxide increases by about 15% (multiplying factor of about 1.15).
- the aluminum oxide content varies by more than 300%.
- the coating 20 has a thickness corresponding to about 300 seconds.
- the layer between 15% and 30% of the coating, measured from the free surface 24 of the coating therefore corresponds to the numbers of shots measured between 45 and 90 seconds. Between 45 and 90 seconds, the number of strokes measured for aluminum oxide increases by more than 300% (multiplicative factor of about 3.4).
- Figures 6 to 7 show photos of the results after a salt spray corrosion test for 168 hours according to ISO 9227, respectively for Examples 1, 2 and 3.
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- Chemical Treatment Of Metals (AREA)
Abstract
Description
Claims
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
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FR1654849A FR3051805B1 (fr) | 2016-05-30 | 2016-05-30 | Procede de chromatation et piece obtenue par ce procede |
PCT/FR2017/051337 WO2017207909A1 (fr) | 2016-05-30 | 2017-05-30 | Procede de chromatation et piece obtenue par ce procede |
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EP3464681A1 true EP3464681A1 (fr) | 2019-04-10 |
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Application Number | Title | Priority Date | Filing Date |
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EP17732979.4A Withdrawn EP3464681A1 (fr) | 2016-05-30 | 2017-05-30 | Procede de chromatation et piece obtenue par ce procede |
Country Status (5)
Country | Link |
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US (1) | US20200040461A1 (fr) |
EP (1) | EP3464681A1 (fr) |
CN (1) | CN109312468A (fr) |
FR (1) | FR3051805B1 (fr) |
WO (1) | WO2017207909A1 (fr) |
Family Cites Families (6)
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JP4633477B2 (ja) * | 2005-01-07 | 2011-02-16 | 株式会社ケーヒン | アルミニウム系有膜鋳造成形品及びその製造方法 |
BRPI0707550B1 (pt) * | 2006-02-14 | 2021-07-27 | Henkel Ag & Co. Kgaa | Composição e processo para revestimento ou para retoque ou tanto para revestimento como para retoque de uma superfície de metal, e, artigo para manufatura |
US8574396B2 (en) * | 2010-08-30 | 2013-11-05 | United Technologies Corporation | Hydration inhibitor coating for adhesive bonds |
FR2986806B1 (fr) * | 2012-02-10 | 2015-03-20 | Mecaprotec Ind | Procede de traitement de surface de pieces en alliage d'aluminium ou de magnesium |
US9903020B2 (en) * | 2014-03-31 | 2018-02-27 | Applied Materials, Inc. | Generation of compact alumina passivation layers on aluminum plasma equipment components |
CN104233273A (zh) * | 2014-09-26 | 2014-12-24 | 山东大学 | 一种用于铝或铝合金表面钝化的无铬硅系钝化液、制备及使用方法 |
-
2016
- 2016-05-30 FR FR1654849A patent/FR3051805B1/fr active Active
-
2017
- 2017-05-30 WO PCT/FR2017/051337 patent/WO2017207909A1/fr unknown
- 2017-05-30 CN CN201780033975.6A patent/CN109312468A/zh active Pending
- 2017-05-30 EP EP17732979.4A patent/EP3464681A1/fr not_active Withdrawn
- 2017-05-30 US US16/305,783 patent/US20200040461A1/en not_active Abandoned
Also Published As
Publication number | Publication date |
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WO2017207909A1 (fr) | 2017-12-07 |
US20200040461A1 (en) | 2020-02-06 |
FR3051805A1 (fr) | 2017-12-01 |
CN109312468A (zh) | 2019-02-05 |
FR3051805B1 (fr) | 2018-06-15 |
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