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
  • C23C22/48—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 not containing phosphates, hexavalent chromium compounds, fluorides or complex fluorides, molybdates, tungstates, vanadates or oxalates
  • C23C22/56—Treatment of aluminium or alloys based thereon
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
  • B05D7/14—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials to metal, e.g. car bodies
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
  • B05D7/50—Multilayers
  • B05D7/56—Three layers or more
  • B05D7/58—No clear coat specified
  • B05D7/584—No clear coat specified at least some layers being let to dry, at least partially, before applying the next layer
• • 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
  • C23C22/73—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 characterised by the process
• • 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
  • C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D13/00—Electrophoretic coating characterised by the process
  • C25D13/22—Servicing or operating apparatus or multistep processes
• • 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

• This presentation relates to the protection, for example against corrosion, of a part comprising an aluminum-based alloy.
• Aluminum-based alloys have the advantage of being light. However, they can be susceptible to corrosion. Also, it is known to protect parts made from aluminum-based alloys against corrosion by carrying out, for example, a chemical conversion of the surface of the part.
• This chemical conversion treatment was generally carried out by bringing the part into contact with a bath containing hexavalent chromium (or chromium VI or Cr VI).
• the bath can be made from a solution such as, for example, the solution commonly designated by the registered trademark Alodine® 1200S from Henkel.
• This chemical conversion treatment is a chromating treatment of the aluminum-based alloy during which the alloy is converted at the surface in order to precipitate therein in particular aluminum oxyhydroxides and aluminum chromates.
• This treatment makes it possible to produce a coating on the surface of the part which increases the resistance to corrosion of the part made of an aluminum-based alloy. Furthermore, this coating makes it possible to retain electrical conductivity of the coated zone and to allow easy and good quality adhesion of organic paints which are generally also based on hexavalent chromium.
• This presentation relates to a method for protecting a part comprising an aluminum-based alloy, the method comprising the following steps:
• the process for protecting aluminum-based alloy parts makes it possible to obtain a treated part which is effectively protected in particular from corrosion by a coating comprising conductive zones (zones having undergone the chemical conversion - conductive protective layer ) and non-conductive areas (areas bearing the non-conductive polymerized primer coat).
• the part has, on the areas protected by the conductive protective layer, less than five pitting per dm 2 (square decimeter) after exposure to neutral salt spray for 168 and 144 hours, respectively for wrought and foundry alloys, according to the requirements of standard NF EN ISO 9227:2017; on the areas protected by the non-conductive polymerized primer coat and/or the finish paint coat after polymerization, the part exhibits acceptable behavior after more than 3000 hours of exposure to neutral salt spray, according to the requirements of the standard EN ISO 9227:2017. It is understood that the non-conductive polymerized primary paint layer does not undergo the chemical conversion. The non-conductive polymerized primer paint layer is not altered or modified by the chemical conversion step.
• the non-conductive polymerized primary paint layer does not pollute the chemical conversion bath.
• the chemical conversion step to trivalent chromium only takes place on the unpainted areas, that is to say the areas not protected against corrosion by the non-conductive polymerized primer paint, which were previously stripped during of the laser etching step.
• the non-conductive polymerized primary paint layer is a non-conductive protective layer.
• Laser stripping makes it possible to expose the part for specific areas where it is desired to have conductive parts of the protection. It is understood that the number of unpainted areas is not limited to one. During the laser stripping step, the non-conductive polymerized primary paint layer is removed only in the areas where electrical continuity between the part and external elements is desired. In these unpainted areas, the part is therefore bare again.
• the chromating bath can be a bath marketed under the SurTec650® or Lanthane 613.3® brand.
• the part After immersion in a chemical conversion and/or anaphoresis bath, the part is rinsed with demineralised water and dried.
• the drying step can be carried out at room temperature under compressed air and/or in an oven at a temperature less than or equal to 60°C (degree Celsius). It is understood that compressed air can be used at room temperature and then put the part in a study at a temperature less than or equal to 60°C until the part is dry.
• finishing coat of paint is for example applied to areas of the part to improve the fluid and UV resistance of the covered areas.
• the finishing paint can be a paint based on polyurethane and/or acrylic (example: Interthane 870/990 from the International supplier).
• finishing coat of paint can be applied by spraying using a pneumatic gun.
• the unpainted area may be cleaned.
• This step makes it possible to remove residues, for example in the form of powder, which may have been formed during the laser etching step.
• the cleaning of the unpainted area can be carried out by mechanical brushing.
• the cleaning of the unpainted area may be assisted by ultrasound.
• the polymerized non-conductive primer paint layer and the unpainted area can be degreased with a solvent and/or an alkaline solution.
• This step makes it possible to degrease the part when the non-conductive polymerized primer paint layer and/or the unpainted zone show dirt of the “fingerprint” type which may result from successive manipulations of the part during the preceding steps.
• the degreasing step is not carried out using an acid solution.
• the solvent may be ethanol or methyl ethyl ketone (butanone-2, also called MEK in accordance with the acronym in English for Methyl Ethyl Ketone).
• the alkaline solution may be a solution marketed under the name Sococlean A3432.
• the non-conductive polymerized primary paint layer may have a thickness greater than or equal to 10 ⁇ m, preferably greater than or equal to 15 ⁇ m and less than or equal to 40 ⁇ m, preferably less than or equal to 30 p.m.
• the laser stripping can be carried out by means of a YAG laser with a wavelength of 1064 nm at a frequency comprised between 10 and 200 kHz.
• a profile of the laser beam may be Gaussian-shaped or flat-topped.
• a flat-top laser beam profile is also called a "Top Hat”.
• the laser beam may have a fluence greater than or equal to 4 J/cm 2 and the laser etching may comprise one to four passes.
• the laser beam may have a fluence less than or equal to 56 J/cm 2 and the laser etching may comprise one to four passes.
• the laser etching can be carried out with a laser beam recovery rate greater than or equal to [0036] 20% and less than or equal to 80%.
• the recovery rate can be in one or both directions of movement of the laser beam.
• the values in the two directions can be different from each other.
• the recovery rate may be equal to 50% in both directions.
• Figure 1 is a flowchart representing the steps of a method of protecting a part comprising an aluminum-based alloy.
• Figure 2 a partial schematic view in section and in perspective of a part with a layer of non-conductive polymerized primer paint.
• Figure 3 is a partial schematic view in section and in perspective of the part of Figure 2 after laser etching.
• Figure 4 is a partial schematic view in section and in perspective of the part of Figure 3 after chemical conversion and drying.
• Figure 5 is a partial schematic view in section and in perspective of the part of Figure 4 after deposition of the finishing paint layer.
• Figure 1 shows a method 100 of protection, in particular against corrosion, of a part 12 comprising an aluminum-based alloy.
• the method 100 comprises a first step 102 of depositing a layer of primary paint by anaphoresis over the entire part 12.
• the step of depositing the layer of primary paint by anaphoresis is followed by a polymerization step 104 of the primer paint layer to obtain a non-conductive polymerized primer paint layer 14 over the entire part 12, as shown in Figure 2.
• Figure 2 is a schematic view in partial section of an element 10. It is therefore understood that the part 12 is completely covered by the non-conductive polymerized primary paint layer 14. A partial view is shown in section to see part 12 and the non-conductive polymerized primer coat 14.
• the deposition step 102 of the protective layer 14 is carried out by anaphoresis.
• Anaphoresis is a process for forming the non-conductive polymerized primary paint layer 14 by immersing the part 12 in a bath of electrically charged paint, and which, under the effect of an electrical voltage applied between the part serving as an anode and a counter-electrode, is deposited on part 12. Once the deposit has reached the thickness desired, the deposit is polymerized at a temperature making it possible to fix the paint on the part 12 and form the non-conductive polymerized primary paint layer 14.
• the Aerocron 2200 electrodeposited paint system mention may be made of the Aerocron 2200 electrodeposited paint system.
• part 12 When part 12 is completely coated with the non-conductive polymerized primary paint layer 14, part 12 is protected in particular against corrosion. However, this protective layer is non-conductive.
• the method 100 includes a laser stripping step 106 using a laser beam of an area of the non-conductive polymerized primary paint layer 14 to form an unpainted area 16, as shown in Figure 3. understands that in the unpainted area 16, part 12 is exposed.
• the laser stripping 106 can be carried out using a YAG laser with a wavelength of 1064 nm at a frequency of between 10 and 200 kHz.
• the profile of the laser beam can be Gaussian or flat-topped.
• the part 12, the non-conductive polymerized primary paint layer 14 has been removed in one area, has an unpainted area 16. It is understood that the number of unpainted areas 16 n ' is not limited to one.
• Figure 3 being a schematic figure, the unpainted area 16 is shown as having the shape of a square. It is understood that this shape is not limiting and that the unpainted area 16 can have any shape.
• the shape of the unpainted area 16 is defined by the passage of the laser beam over the non-conductive polymerized primary paint layer 14.
• the method 100 includes a step 108 of chemical conversion to trivalent chromium of the unpainted area 16 to form a conductive protective layer 18, as shown in Figure 4.
• the non-conductive polymerized primary paint layer 14 is not altered or modified by the chemical conversion step 108.
• the chemical conversion step 106 to trivalent chromium does not takes place only on the unpainted areas 16 which have been previously stripped during the laser stripping step 106 and the formation of the conductive protective layer 18 is formed only at the location of the unpainted areas 16.
• the method 100 includes a drying step 110.
• the drying step 110 can be carried out at room temperature under compressed air and/or in an oven at a temperature less than or equal to 60 °C (degree Celsius). It is understood that compressed air can be used at room temperature and then put part 12 in a study at a temperature less than or equal to 60°C until part 12 is dry.
• the method 100 includes a step 112 of depositing a layer of finishing paint on at least a portion of the non-conductive polymerized primary paint layer.
• the method 100 includes a step 114 of polymerization of the finish paint layer to form a layer of polymerized finish paint 20 on the layer of non-conductive polymerized primer paint 18, as shown schematically in Figure 5.
• the polymerized finishing paint layer 20 may not cover all of the non-conductive polymerized primer paint layer 18, as shown schematically in Figure 5.
• the method 100 can also include a cleaning step 116 of the unpainted area 16 after the laser stripping step 106.
• the unpainted area or areas 16 are covered with a light dusting due to laser stripping, it is advantageous to clean the unpainted areas 16 to remove these residues, for example in the form of powder, which may have been formed during of the laser etching step 106.
• the cleaning 116 of the unpainted area 16 can be carried out by mechanical brushing.
• the cleaning 116 of the unpainted area 16 can be assisted by ultrasound.
• the method 100 may also include a degreasing step 118 of the non-conductive polymerized primary paint layer 14 and of the unpainted area 16 after the laser stripping step 106.
• the degreasing step 118 may or may not be carried out after the cleaning step 116.
• the part 12 and the non-conductive polymerized primary paint layer 14 can be degreased 118 with a solvent and/or an alkaline solution.
• This step makes it possible to degrease the part when the layer of non-conductive polymerized primer paint 14 and/or the unpainted zone 16 show dirt of the "fingerprint" type which may result from successive manipulations of the part during previous steps.
• degreasing step 118 is not carried out using an acid solution.
• the solvent may be ethanol or methyl ethyl ketone (butanone-2, also called MEK in accordance with the acronym in English for Methyl Ethyl Ketone
• the alkaline solution may be a solution marketed under the name Sococlean A3432.

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• Application Of Or Painting With Fluid Materials (AREA)
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• 2020
  • 2020-12-03 FR FR2012621A patent/FR3117131B1/fr active Active
• 2021
  • 2021-11-25 CN CN202180081348.6A patent/CN116583625A/zh active Pending
  • 2021-11-25 US US18/255,646 patent/US20240009700A1/en not_active Abandoned
  • 2021-11-25 EP EP21830452.5A patent/EP4256105B1/de active Active
  • 2021-11-25 WO PCT/FR2021/052092 patent/WO2022117935A1/fr not_active Ceased
• 2023
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