US20170342587A1 - Object processing by conversion coating - Google Patents

Object processing by conversion coating Download PDF

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Publication number
US20170342587A1
US20170342587A1 US15/534,359 US201515534359A US2017342587A1 US 20170342587 A1 US20170342587 A1 US 20170342587A1 US 201515534359 A US201515534359 A US 201515534359A US 2017342587 A1 US2017342587 A1 US 2017342587A1
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Prior art keywords
conversion coating
aircraft part
onto
initial
conversion
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US15/534,359
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English (en)
Inventor
Sam Oliver Ashworth
Craig Bowden
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BAE Systems PLC
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BAE Systems PLC
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Assigned to BAE SYSTEMS PLC reassignment BAE SYSTEMS PLC ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: BOWDEN, Craig, Ashworth, Sam Oliver
Publication of US20170342587A1 publication Critical patent/US20170342587A1/en
Abandoned legal-status Critical Current

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    • 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
    • C25D11/022—Anodisation on selected surface areas
    • 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
    • C23C22/24—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 hexavalent chromium compounds
    • 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
    • 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
    • C23C22/82—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
    • 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
    • C23C22/82—After-treatment
    • C23C22/83—Chemical 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
    • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
    • C23F1/00—Etching metallic material by chemical means
    • C23F1/02—Local etching
    • 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
    • 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
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
    • C25D11/02—Anodisation
    • C25D11/04—Anodisation of aluminium or alloys based thereon
    • C25D11/06—Anodisation of aluminium or alloys based thereon characterised by the electrolytes used
    • C25D11/08—Anodisation of aluminium or alloys based thereon characterised by the electrolytes used containing inorganic acids
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
    • C25D11/02—Anodisation
    • C25D11/04—Anodisation of aluminium or alloys based thereon
    • C25D11/18—After-treatment, e.g. pore-sealing
    • C25D11/24—Chemical after-treatment
    • C25D11/246—Chemical after-treatment for sealing layers
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
    • C25D11/38—Chromatising
    • 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
    • C25D11/10—Anodisation of aluminium or alloys based thereon characterised by the electrolytes used containing organic 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
    • C25D11/12—Anodising more than once, e.g. in different baths
    • 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
    • C25D11/36—Phosphatising

Definitions

  • the present invention relates to the processing of objects.
  • some regions of the surface of an aircraft part are chromate conversion coated, while the remaining regions of the parts of the surface of an aircraft part are anodised.
  • Typically, only the chromic acid anodised regions of the aircraft part are painted, while the chromate conversion coated regions of the aircraft part are left unpainted.
  • FIG. 1 is a process flow chart showing certain steps of an example conventional process for painting an aircraft part.
  • the unpainted aircraft part is masked by selectively applying masking tape to certain regions of the aircraft part.
  • masking tape may be performed using 3M 425 Aluminium Foil Tape.
  • such masking processes including cutting making tape to desired shaped and applying the cut masking tape to the aircraft part, may take about 3 hours.
  • the masked unpainted aircraft part is anodised.
  • an anodic layer or oxide layer is formed on the unmasked surface of the aircraft part.
  • this step of anodising the aircraft part may take about 1 hour.
  • the anodised aircraft part is de-masked and cleaned.
  • the masking tape applied to the aircraft part at step s 2 is removed.
  • any adhesive residue left on the aircraft part by the masking tape is wiped from the aircraft part. Solvents or other cleaning chemicals may be used to remove the adhesive residue.
  • this step of de-masking and cleaning the aircraft part may take about 1 hour.
  • the cleaned aircraft part is prepared for chromate conversion coating.
  • preparation of the aircraft part includes selectively masking (for example, using masking tape and/or paper) the aircraft part.
  • the anodised regions of the aircraft part may be masked.
  • the prepared aircraft part is chromate conversion coated.
  • the aircraft parts is chromate conversion coated by hand.
  • a human being manually applies a chromate conversion layer to the un-anodised regions of the surface of the aircraft part.
  • each region of the surface of the aircraft part is either chromate conversion coated or anodised.
  • the steps of preparing the aircraft part for chromate conversion coating, and chromate conversion coating the aircraft part may take about 2 hours.
  • the chromate conversion coated aircraft part is cleaned.
  • cleaning may include the use of clean, cold water.
  • this step of cleaning the chromate conversion coated aircraft part may take about 1 hour.
  • the cleaned aircraft part is masked by selectively applying masking tape to certain regions of the aircraft part.
  • masking tape In this example, only chromate conversion coated regions of the aircraft part are masked. Also, only anodised regions of the aircraft part are unmasked.
  • the masked aircraft part is painted.
  • paint is only applied to unmasked (i.e. anodised) regions of the aircraft part. Masked, chromate conversion coated regions of the aircraft part are left unpainted.
  • this step of painting the aircraft part may take about 3 hours.
  • the masking tape applied to the aircraft part at step s 14 is removed after the paint has dried.
  • the present inventors have realised that, using a conventional method such as that described in more detail above with reference to FIG. 1 , paint tends not to adhere correctly to the aircraft part in certain regions.
  • the present inventors have realised that, at least during de-masking and cleaning process (such as that performed at step s 6 of FIG. 1 ), residue from the masking tape may remain on the aircraft part.
  • the present inventors have also realised that such masking tape residue may be spread to previously unmasked regions of the aircraft part during cleaning e.g. after or during a de-masking process.
  • masking tape residue tends to detrimentally effect the adhesion of paint to the aircraft part.
  • the present inventors have further realised that aircraft parts undergoing a conventional painting process, such as that described in more detail earlier above with reference to FIG. 1 , tend to exhibit blemishes and/or superficial damage.
  • inspection tape used during paint adhesion tests may remove paint from that painted aircraft part.
  • tools such as scalpels
  • Use of such tools may cause damage, such as scratches, to the aircraft part which may introduce stress concentration points to a part.
  • the present invention provides a method of processing an object, the method comprising: performing a first conversion coating process to dispose a first conversion coating onto at least part of a surface of the object; partially masking the first conversion coating disposed on the object; performing an etching process to remove, from the object, an unmasked portion of the first conversion coating while retaining the masked portion of the first conversion coating on the object; and performing a second conversion coating process to dispose a second conversion coating onto a region of the surface of the object from which the unmasked portion of the first conversion coating was removed.
  • the first conversion coating process may be a chromate conversion coating process.
  • the first conversion coating may be a chromate conversion layer.
  • the first conversion coating may be different to the second conversion coating.
  • the first conversion coating may be relatively electrically conductive.
  • the second conversion coating may be relative electrically resistive, i.e. the first conversion coating may have a higher conductivity than the second conversion coating.
  • the method may further comprise applying a layer of paint onto either the second conversion coating or the portion of the first conversion coating retained on the object.
  • the layer of paint may be applied onto the second conversion coating and not onto the portion of the first conversion coating retained on the object.
  • the method may further comprise, after the second conversion coating process, de-masking the object.
  • the first conversion coating process may comprise disposing the first conversion coating onto the entirety of the surface of the object, i.e. over the whole surface of the object.
  • the second conversion coating process may be an anodising process.
  • the second conversion coating may be an anodic layer.
  • the object may be at least part of an aircraft.
  • the object may be made of a metal or alloy such as aluminium or aluminium alloy.
  • the first conversion coating may define an electrically conductive path through at least part of the coated object.
  • the first conversion coating may define an electrically conductive path through at least part of the part of an aircraft for the transmission of lightning strike energy.
  • the first conversion coating process may comprise: exposing at least part of the object to a cleaning substance; rinsing the object to remove the cleaning substance from the object; exposing at least part of the object to a first conversion coating substance, thereby disposing the first conversion coating onto the at least part of a surface of the object; and rinsing the object to remove residual first conversion coating substance from the object.
  • the etching process may comprise: exposing at least part of the object to a cleaning substance; rinsing the object to remove the cleaning substance from the object; exposing at least part of the object to an etching substance, thereby removing, from the object, an unmasked portion of the first conversion coating; and rinsing the object to remove residual etching substance from the object.
  • the second conversion coating process may comprise: exposing at least part of the object to a cleaning substance; rinsing the object to remove the cleaning substance from the object; exposing at least part of the object to a second conversion coating substance, thereby disposing the second conversion coating onto the at least part of a surface of the object; and rinsing the object to remove residual second conversion coating substance from the object.
  • Partially masking the first conversion coating disposed on the object may comprise applying vinyl tape (for example, a 3M 484 vinyl tape) onto part of the first conversion coating.
  • vinyl tape for example, a 3M 484 vinyl tape
  • the present invention provides apparatus for processing an object, the apparatus comprising: means for performing a first conversion coating process to dispose a first conversion coating onto at least part of a surface of the object; masking means for partially masking the first conversion coating disposed on the object; means for performing an etching process to remove, from the object, an unmasked portion of the first conversion coating while retaining the masked portion of the first conversion coating on the object; and means for performing a second conversion coating process to dispose a second conversion coating onto a region of the surface of the object from which the unmasked portion of the first conversion coating was removed.
  • the present invention provides an object that has been processed using a method according to any of the above objects. Such objects tend to be discernible from objects that have undergone conventional treatments such as that described in more detail above with reference to FIG. 1 .
  • the object may be at least part of an aircraft.
  • the present invention provides an aircraft comprising an object according to the preceding aspect.
  • the present invention provides a method of producing an aircraft including a method of processing an object according to any of the preceding aspects, the object being at least part of the aircraft.
  • FIG. 1 is a process flow chart showing certain steps of an example conventional process for painting an aircraft part
  • FIG. 2 is a schematic illustration (not to scale) of a painted aircraft part
  • FIG. 3 is a process flow chart showing certain steps of an embodiment of a process for painting an aircraft part
  • FIG. 4 is a process flow chart showing certain steps of a process of chromate conversion coating the aircraft part
  • FIG. 5 is a process flow chart showing certain steps of a process of selectively stripping the aircraft part.
  • FIG. 6 is a process flow chart showing certain steps of anodising the aircraft part.
  • FIG. 2 is a schematic illustration (not to scale) of a painted aircraft part 2 .
  • the painted aircraft part 2 may be any appropriate aircraft part, for example, a trailing edge spar, left hand horizontal tail, STOVL, or an aircraft frame.
  • the painted aircraft part 2 comprises an initial aircraft part 4 to which coatings have been applied.
  • a surface of the initial aircraft part 4 comprises two regions, namely a first region 6 and second region 8 .
  • the initial aircraft part 4 is made of a metal or alloy such as aluminium or aluminium alloy.
  • the painted aircraft part 2 comprises a chromate conversion coating or layer 10 .
  • the chromate conversion layer 10 is disposed on the first region 6 of the surface of the initial aircraft part 4 .
  • the chromate conversion layer 10 is a chromate conversion film formed from potassium dichromate.
  • the painted aircraft part 2 further comprises an anodic coating or layer 12 .
  • the anodic layer 12 is disposed on the second region 8 of the surface of the initial aircraft part 4 .
  • the painted aircraft part 2 further comprises a paint layer 14 .
  • the paint layer 14 is disposed on the anodic layer 12 such that the anodic layer 12 is sandwiched between the paint layer 14 and the second region 8 of the surface of the initial aircraft part 4 .
  • FIG. 3 is a process flow chart showing certain steps of an embodiment of a process for painting an aircraft part.
  • the uncoated aircraft part i.e. the initial aircraft part 4 without the coatings 10 , 12 , 14 applied
  • the entirety of the surface of the initial aircraft part 4 including the first and second regions 6 , 8 , is chromate conversion coated.
  • a process of chromate conversion coating the entirety of the surface of the initial aircraft part 4 is described in more detail later below with reference to FIG. 4 .
  • the chromate conversion coated initial aircraft part 4 is masked by selectively applying masking tape to certain regions of its surface.
  • the masking tape used to mask the chromate conversion coated initial aircraft part 4 is 3M 484 electroplating and anodizing vinyl tape, often referred to as “yellow tape”.
  • the chromate conversion coating is stripped from the unmasked regions of the surface of the chromate conversion coated initial aircraft part 4 .
  • a process of stripping the chromate conversion coating from the unmasked regions of the surface of the initial aircraft part 4 is described in more detail later below with reference to FIG. 5 .
  • the chromate conversion coating is stripped from the second region 8 of the surface of the initial aircraft part 4 . Also, the chromate conversion layer 10 remains disposed on the masked first region 6 of the surface of the initial aircraft part 4 .
  • the selectively stripped initial aircraft part 4 (with the chromate conversion layer 10 and masking tape applied to the first region 6 of its surface) is anodised.
  • a process of anodising the selectively stripped initial aircraft part 4 is described in more detail later below with reference to FIG. 6 .
  • Anodising the selectively stripped initial aircraft part 4 forms the anodic layer 12 only on the unmasked regions of the surface of the initial aircraft part 4 .
  • the anodic layer 12 is formed on the second region 8 of the surface of the initial aircraft part 4 and not on the first region 6 of the surface of the initial aircraft part 4 .
  • the below described process of applying paint to the aircraft part is performed within 16 hours of anodising the initial aircraft part 4 .
  • the paint layer 14 is applied to the anodised initial aircraft part 4 , thereby forming the painted aircraft part 2 .
  • the paint layer 14 is only applied to the unmasked regions of the surface of the initial aircraft part 4 .
  • the paint layer 14 is disposed on the anodic layer 12 on the second region 8 of the surface of the initial aircraft part 4 .
  • the paint layer 14 is not applied to the first region 6 of the surface of the initial aircraft part 4 .
  • the paint layer 14 may include multiple paint layers, e.g. a primer layer and a top coat.
  • FIG. 4 is a process flow chart showing certain steps of an embodiment of a process of chromate conversion coating the entirety of the surface of the initial aircraft part 4 .
  • the initial aircraft part 4 is prepared.
  • preparation of the initial aircraft part 4 includes, but is not limited, checking the initial aircraft part 4 for signs of damage (e.g. abrasions, nicks, scratches, etc.) or excessive contamination, and ensuring all heat treatments, machining, welding, brazing, forming, and flaw detection processes that have been performed on the initial aircraft part 4 have been performed satisfactorily.
  • the preparation process may be performed by a human being, or may be an automated process.
  • the damaged initial aircraft part 4 may be referred for further inspection or repair.
  • the initial aircraft part 4 is wholly submerged in alkaline cleaner.
  • the alkaline cleaner is Turco 4215 NCLT having a concentration of between 40 g/l and 60 g/l.
  • the temperature of the alkaline cleaner is between 45° C. and 55° C.
  • the initial aircraft part 4 is submerged in the alkaline cleaner for between 2 mins and 10 mins.
  • the cleaned initial aircraft part 4 is drained.
  • the initial aircraft part 4 is not left to completely dry.
  • Draining of the alkaline cleaner from the cleaned initial part 4 tends to reduce or eliminate contamination of subsequent processing liquids by the alkaline cleaner.
  • the drained initial aircraft part 4 is rinsed.
  • rinsing of the drained initial aircraft part comprises spraying the initial aircraft part 4 using clean, cold, running water for between 5 mins and 60 mins.
  • Rinsing of the initial aircraft part 4 tends to ensure complete removal of any residual alkaline cleaner.
  • step s 38 the rinsed initial aircraft part 4 is inspected.
  • the rinsed initial aircraft part 4 is inspected for a water break free surface. If a water break free surface of the initial aircraft part 4 is visible, the method proceeds to step s 40 . However, if a water break is observed on the initial aircraft part 4 , the process returns to step s 32 .
  • This inspection of the initial aircraft part 4 may be performed by a human being or automatically.
  • the initial aircraft part 4 is wholly submerged in an etching solution.
  • the etching solution is an agitated acid solution.
  • the acid solution is a so-called “deoxidiser” solution which may be a “de-smut” solution.
  • the deoxidiser solution is Deoxidiser 7/17 (as Cr6+) having a concentration of between 4.5 g/l and 10.5 g/l.
  • the initial aircraft part 4 is submerged in the deoxidiser solution for between 5 mins and 10 mins.
  • step s 42 the initial aircraft part 4 is rinsed. This rinsing process may be performed in the same or a similar way to that performed at step s 36 for between 5 mins and 60 mins.
  • Rinsing of the initial aircraft part 4 tends to ensure complete removal of any residual deoxidiser solution.
  • the rinsed initial aircraft part 4 is wholly submerged in chromate conversion coating solution.
  • the chromate conversion coating solution is Alocrom 1200.
  • the initial aircraft part 4 is submerged in the chromate conversion coating solution for between 2 mins and 3 mins.
  • the chromate conversion layer 10 is applied across the whole surface of the initial aircraft part 4 .
  • step s 46 the chromate conversion coated initial aircraft part 4 is rinsed. This rinsing process may be performed in the same or a similar way to that performed at step s 36 for between 2 mins and 5 mins without spray.
  • Rinsing of the initial aircraft part 4 tends to ensure complete removal of any residual chromate conversion coating solution.
  • step s 48 the rinsed initial aircraft part 4 is completely dried.
  • the rinsed initial aircraft part 4 is air dried at a temperature of less than or equal to 60° C. for at least 10 mins.
  • step s 50 the dried initial aircraft part 4 is inspected.
  • the dried initial aircraft part 4 is inspected for the presence of damage, detached deposit, and non-adherent or powdery coating. Detection of non-adherent or powdery chromate conversion coating may be performed by rubbing the surface of the coated initial aircraft part 4 , for example, using a test paper such as Whatman, Style No. 40 filter paper.
  • the initial aircraft part may be re-processed, for example, using one or more of the above described process steps.
  • This inspection of the dried initial aircraft part 4 may be performed by a human being or automatically.
  • step s 50 After the inspection process of step s 50 , the process proceeds to masking step s 22 described in more detail earlier above with reference to FIG. 3 .
  • the below described process of applying paint to the aircraft part is performed within 16 hours of the chromate conversion coating the initial aircraft part 4
  • FIG. 5 is a process flow chart showing certain steps of an embodiment of a process of stripping the chromate conversion coating from the unmasked regions of the surface of the initial aircraft part 4 .
  • step s 52 the selectively masked chromate conversion coated initial aircraft 4 part is prepared.
  • preparation of the aircraft part 4 includes, but is not limited, checking the initial aircraft part 4 for signs of damage. In some embodiments, if damage or the like is detected on the initial aircraft part 4 , no further steps of the painting process are performed, and the damaged initial aircraft part 4 may be referred for further inspection or repair.
  • the conversion coated area Prior to masking, the conversion coated area may be solvent wiped to ensure any debris collected between processes is removed and the masking adheres to the conversion coated surface.
  • Edges of masked areas may be sealed and masking tape boundaries may be overlapped with further masking tape. This tends to reduce or eliminate ingress of treatment liquids into masked areas of the aircraft part.
  • the preparation process may be performed by a human being, or may be an automated process.
  • the masked initial aircraft part 4 is wholly submerged in alkaline cleaner. This cleaning process may be performed in the same or a similar way to that performed at step s 32 for 5-10 minutes.
  • the masked initial aircraft part 4 is drained. In this embodiment, the masked initial aircraft part 4 is not left to completely dry.
  • step s 58 the drained initial aircraft part 4 is rinsed. This rinsing process may be performed in the same or a similar way to that performed at step s 36 for between 4-6 minutes.
  • step s 60 the rinsed initial aircraft part 4 is inspected. This inspection process may be performed in the same or a similar way to that performed at step s 38 .
  • the rinsed initial aircraft part 4 is wholly submerged in etching solution or stripping solution.
  • the etching solution is, for example, Aluminetch #2.
  • the initial aircraft part 4 is submerged in the etching solution for between 1 min and 2 mins.
  • the chromate conversion layer 10 is etched, i.e. removed, from the unmasked regions of the surface of initial aircraft part 4 , for example, from the second region 8 .
  • the timings tend to be such that minimal aluminium is removed and only conversion coating film is removed.
  • step s 64 the etched initial aircraft part 4 is rinsed. This rinsing process may be performed in the same or a similar way to that performed at step s 36 for between 2 mins and 5 mins.
  • Rinsing of the initial aircraft part 4 tends to ensure complete removal of any residual etching solution and stops any further etching.
  • the rinsed initial aircraft part 4 is wholly submerged in deoxidiser solution e.g. to perform a “de-smut” operation.
  • This deoxidising process may be performed in the same or a similar way to that performed at step s 40 for a maximum of 30 seconds.
  • step s 68 the de-oxidised initial aircraft part 4 is rinsed. This rinsing process may be performed in the same or a similar way to that performed at step s 36 for between 4 mins and 6 mins.
  • step s 68 After the rinsing process of step s 68 , the process proceeds to anodising step s 26 .
  • FIG. 6 is a process flow chart showing certain steps of an embodiment of a process of anodising the selectively stripped initial aircraft part 4 .
  • the selectively stripped initial aircraft 4 part is prepared. Preparation may be performed in the same or a similar way to that performed at step s 30 or s 52 above.
  • the selectively stripped initial aircraft part 4 is wholly submerged in alkaline cleaner. This cleaning process may be performed in the same or a similar way to that performed at step s 32 .
  • the selectively stripped initial aircraft part 4 is drained.
  • the masked initial aircraft part 4 is not left to completely dry.
  • step s 76 the drained initial aircraft part 4 is rinsed. This rinsing process may be performed in the same or a similar way to that performed at step s 36 for between 5 mins and 60 mins.
  • step s 78 the rinsed initial aircraft part 4 is inspected. This inspection process may be performed in the same or a similar way to that performed at step s 38 .
  • step s 80 the initial aircraft part 4 is wholly submerged in deoxidiser solution. This deoxidation process may be performed in the same or a similar way to that performed at step s 40 .
  • step s 82 the initial aircraft part 4 is rinsed. This rinsing process may be performed in the same or a similar way to that performed at step s 42 .
  • step s 84 the rinsed initial aircraft part 4 is inspected.
  • the rinsed aircraft part is inspected for, for example, signs of contamination, defects, and damage.
  • This inspection process may be performed by a human being, or may be an automated process.
  • the damaged initial aircraft part 4 may be referred for further inspection or repair.
  • step s 86 the rinsed, selectively stripped aircraft part 4 is connected to an anode.
  • step s 88 the selectively stripped initial aircraft part 4 is wholly submerged in anodising electrolyte.
  • the anodising electrolyte comprises: free chromic acid having a concentration of between 30 g/l to 50 g/l; a sulphate (e.g. Na 2 SO 4 ) having a maximum concentration of 0.5 g/l; a chloride (e.g. as NaCl) having a maximum concentration of 0.2 g/l; and water.
  • the maximum total chromium content of the anodising electrolyte is 100 g/l.
  • the operating temperature of the anodising electrolyte is between 35° C. and 40° C.
  • a voltage is applied to the selectively stripped initial aircraft part 4 via the anode connected thereto.
  • the voltage applied to the anode is increased from 0V to 22V (+/ ⁇ 2V) at a rate not exceeding 7V/min.
  • the maximum voltage of 22V (+/ ⁇ 2V) is then maintained for between 30 min and 60 min.
  • the voltage is then reduced to less than or equal to 5V.
  • This reducing of the voltage to less than or equal to 5V, allows for the initial aircraft part 4 to be retained in the anodising electrolyte for an addition time period, for example, for an additional 5 mins maximum, if desired.
  • the anodised initial aircraft part 4 is drained. In this embodiment, the anodised initial aircraft part 4 is not left to completely dry.
  • the anodised initial aircraft part 4 is rinsed at least once. This rinsing process may be performed in the same or a similar way to that performed at step s 36 for at least 5 mins.
  • Rinsing e.g. multiple rinsing
  • the initial aircraft part 4 tends to ensure complete removal of any residual anodising electrolyte.
  • step s 96 the rinsed initial aircraft part 4 is inspected. This inspection process may be performed in the same or a similar way to that performed at step s 50 .
  • the anodised initial aircraft part 4 is wholly submerged in a sealing solution.
  • the sealing solution is a dichromate seal.
  • the sealing solution comprises: potassium dichromate having a concentration of between 0.1 g/l to 0.15 g/l; a silicate having a maximum concentration of 7.5 ppm; a sulphate having a maximum concentration of 90 ppm; a chloride having a maximum concentration of 50 ppm; and water.
  • the anodised initial aircraft part 4 is submerged in the sealing solution for 10 mins (+/ ⁇ 2 mins).
  • the operating temperature of the sealing solution is 91° C. (+/ ⁇ 3° C.).
  • step s 100 the rinsed initial aircraft part 4 is completely dried. This drying process may be performed in the same or a similar way to that performed at step s 48 .
  • step s 102 the dried aircraft part 4 is inspected. This inspection process may be performed in the same or a similar way to that performed at step s 50 .
  • step s 102 After the inspection process of step s 102 , the process proceeds to painting step s 28 . Further inspection processes may be performed after anodising has been performed, and prior to the painting of the unmasked regions of the initial aircraft part 4 .
  • the above described process for painting an aircraft part advantageously tends to be much quicker than conventional process. For example, whereas conventional painting processes typically take around 11 hours to complete, the above described painting process may be performed in around 2.5 hours. Thus, the above described method tends to provide significant time and cost savings.
  • the above described process tends to provide improved better paint adhesion to the aircraft part.
  • the masking tape used in the above described process tends not to be removed until the painting process has been completed. Thus, there tends to be no masking tape residue left beneath the paint layer from de-masking cleaning operations. This advantageously tends to improve paint adhesion.
  • the number of times an aircraft part is masked and de-masked during painting is advantageously reduced.
  • the number of times masking is removed from the aircraft part during painting tends to be advantageously reduced. This tends to reduce the use of tools (such as scalpels) to remove masking tape from the aircraft part. This tends to reduce the likelihood of damage (e.g. scratches etc.) to the surface of the aircraft part.
  • tools such as scalpels
  • the masking tape used in the above described process (which may be applied in a pre-cut form or may be cut at time of application to the aircraft part) is a vinyl type. This tends to allow for the use of plastic tools to remove the tape from the aircraft part following application.
  • the aluminium based foil used in conventional processes tends to be difficult to remove and tended to bake onto the surface of the aircraft part, for example, during the anodise process which exotherms as a result of the electrolytic process, or during a paint curing process.
  • the above described method tends to have a reduced use of solvents compared to conventional methods. Also, a need to manually (i.e. by hand) chromate conversion coat the aircraft part tends to be eliminated. Thus, detrimental health effects to humans caused by solvents etc. tend to be reduced.
  • the above described method may be wholly or partially automated.
  • the aircraft part may be mounted to a frame or jig and processed as described above by moving the frame or jig between treatment stations.
  • Automated application of, for example, the chromate conversion coating tends to produce higher quality and more repeatable finish.
  • the improved finish due at least in part to the improved finish, it tends to be possible to discern aircraft parts processed using the above described process from those processed using a conventional process. For example, it tends to be possible to discern aircraft parts conversion coated using the above described process from those conversion coated using a conventional process. Also, it tends to be possible to discern aircraft parts painted using the above described process from those painted using a conventional process.
  • the above described process may be implemented as a production line process.
  • the above described process may be implemented to process multiple aircraft parts simultaneously.
  • the chromate conversion coating is relatively electrically conductive whereas the anodic (or oxide) is relatively electrically resistive.
  • the chromate conversion coating defines an electrically conductive path through at least part of painted aircraft part. Such an electrically conductive path may be, for example, for transmitting a lightning strike safely through the aircraft.
  • an aircraft part is painted.
  • a different type of object may be painted, for example a part of a different vehicle such as a land-based or water-based vehicle.
  • the above described alkaline cleaning or deoxidising operations may be, for example, air powered (oil free), or liquid agitation processes.
  • the various treatment liquids, treatment times, voltage cycles, and treatment temperatures etc. are as described in more detail earlier above.
  • one or more different appropriate treatment liquids, and/or other types of treatment such as treatment using a gas or vapour
  • a different treatment time may be used instead of one or more of the above mentioned treatment times.
  • a different treatment temperature may be used instead of one or more of the above mentioned treatment temperatures.
  • a different voltage cycle may be used instead of one or more of the above mentioned voltage cycles.
  • a chromate conversion layer is applied to the aircraft part using a chromate conversion coating process.
  • a different type of conversion coating is applied to the aircraft part instead of or in addition to the chromate conversion coating layer.
  • a phosphate conversion coating process, or an anodising process is used instead of or in addition to the chromate conversion coating process.
  • an anodic layer is applied to the aircraft part using an anodising process, which may be regarded as a type of conversion coating process.
  • anodising process which may be regarded as a type of conversion coating process.
  • a different type of conversion coating is applied to the aircraft part instead of or in addition to the anodic layer.
  • a tartaric anodic process, or a different anodising process is used instead of or in addition to the chromic acid anodising process.
  • the masking tape used to mask the chromate conversion coated initial aircraft part is 3M 484 electroplating and anodizing vinyl tape.
  • a different type of making tape is used to perform the masking process.
  • a different vinyl tape may be used, e.g. P21 “Green Tape” which, for example, may be used in masking processes performed up to about 220° C.
  • the type of masking tape used in the masking process may be selected depending upon properties of the masking tape and the object being masked. For example, a thicker and/or less flexible masking tape may selected for application onto and the masking of relatively flat surfaces of an object, and may, for example, be applied as a pre-cut template. In contrast, a thinner and/or more flexible masking tape may be selected for application onto and the masking of relatively highly curved surfaces of an object, such as double curved surfaces. Such selection of an appropriate making tape advantageously tends to facilitate the making process, and moreover tends to provide for an improved mask.
  • conversion coating may be used herein to refer to processes including, but not limited to: coatings for metals where the part surface is converted into the coating with a chemical or electro-chemical process, chromate conversion coatings, phosphate conversion coatings, bluing, black oxide coatings on steel, plating and anodizing. Conversion coating may be applied to any appropriate material including but not limited to titanium, magnesium, niobium, aluminium or tantalum parts. Anodizing may be regarded as a conversion coating process generated by a combination of both chemical conversion and electric current at an object's surface.

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  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Mechanical Engineering (AREA)
  • Inorganic Chemistry (AREA)
  • Chemical Treatment Of Metals (AREA)
  • Application Of Or Painting With Fluid Materials (AREA)
US15/534,359 2014-12-17 2015-12-09 Object processing by conversion coating Abandoned US20170342587A1 (en)

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Publication number Priority date Publication date Assignee Title
EP4187000A1 (de) * 2021-11-25 2023-05-31 BAE SYSTEMS plc Komponentenverarbeitung

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US5698316A (en) * 1996-10-07 1997-12-16 The Boeing Company Apparatus and methods of providing corrosion resistant conductive path across non conductive joints or gaps
US20090311534A1 (en) * 2008-06-12 2009-12-17 Griffin Bruce M Methods and systems for improving an organic finish adhesion to aluminum components
US20120152893A1 (en) * 2010-12-21 2012-06-21 United Technologies Corporation Method for securing a sheath to a blade
US20140319276A1 (en) * 2011-09-14 2014-10-30 Mitsubishi Aircraft Corporation Aircraft window and aircraft

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CA2279084C (en) * 1998-09-11 2013-12-03 Steven G. Keener Method for coating faying surfaces of aluminum-alloy components and faying surfaces coated thereby
US8398841B2 (en) * 2009-07-24 2013-03-19 Apple Inc. Dual anodization surface treatment

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US2885273A (en) * 1956-03-14 1959-05-05 North American Aviation Inc Method of etching metallic materials
US2993847A (en) * 1958-04-04 1961-07-25 Burroughs Corp Aluminum treating process
US5698316A (en) * 1996-10-07 1997-12-16 The Boeing Company Apparatus and methods of providing corrosion resistant conductive path across non conductive joints or gaps
US20090311534A1 (en) * 2008-06-12 2009-12-17 Griffin Bruce M Methods and systems for improving an organic finish adhesion to aluminum components
US20120152893A1 (en) * 2010-12-21 2012-06-21 United Technologies Corporation Method for securing a sheath to a blade
US20140319276A1 (en) * 2011-09-14 2014-10-30 Mitsubishi Aircraft Corporation Aircraft window and aircraft

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP4187000A1 (de) * 2021-11-25 2023-05-31 BAE SYSTEMS plc Komponentenverarbeitung

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GB2536098A (en) 2016-09-07
GB201521655D0 (en) 2016-01-20
AU2015365719A1 (en) 2017-06-29
GB2536098B (en) 2019-08-28
EP3234231B1 (de) 2020-08-19
WO2016097695A1 (en) 2016-06-23
EP3234231B8 (de) 2020-11-04
EP3234231A1 (de) 2017-10-25

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