Method of treating a surface of an aircraft part

Abstract

One aspect of the invention relates to a method for treating a surface of an aircraft part, the surface comprising a metallic material, the method comprising steps of: - mattifying (E6) the surface of the aircraft part, and - treating (E10) the mattified surface of the aircraft part by applying a laser beam. Figure to be published with the abstract: Figure 2

Description

Title of the invention: Method for treating a surface of an aircraft part TECHNICAL FIELD OF THE INVENTION

[0001] The technical field of the invention is that of aeronautics, and more particularly that of the manufacture of assembled parts for aircraft engines. The invention relates more particularly to the surface treatment of aircraft engine parts.

[0002] In particular, the invention relates to a method of treating a surface of an aircraft part. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0003] Climate change is a major concern for many legislative and regulatory bodies around the world. Indeed, various restrictions on carbon emissions have been, are being, or will be adopted by various states. In particular, an ambitious standard applies both to new types of aircraft and those currently in circulation, requiring the implementation of technological solutions to make them compliant with current regulations. Civil aviation has been mobilizing for several years now to make a contribution to the fight against climate change.

[0004] Technological research efforts have already made it possible to significantly improve the environmental performance of aircraft. The Applicant takes into consideration the impact factors in all phases of design and development to obtain less energy-intensive, more environmentally friendly aeronautical components and products whose integration and use in civil aviation have moderate environmental impacts with the aim of improving the energy efficiency of aircraft.

[0005] Consequently, the Applicant is constantly working to reduce its climate impact by using methods and operating virtuous development and manufacturing processes and minimizing greenhouse gas emissions to the minimum possible in order to reduce the environmental footprint of its activity.

[0006] This sustained research and development work covers new generations of aircraft engines, the lightening of aircraft, particularly through the materials used and lighter on-board equipment, the development of the use of electrical technologies to ensure propulsion, and, as essential complements to technological progress, aeronautical biofuels.

[0007] In this regard, techniques for manufacturing and processing parts Aircraft manufacturing techniques that do not use chemicals are increasingly developing. Laser surface treatment is one of these techniques.

[0008] More particularly, laser surface cleaning is a method which consists of removing undesirable elements present on an outer layer of a metal surface by irradiating this surface with a laser beam. The undesirable elements are, for example, metal oxides which have formed on this metal surface or organic pollution deposited on the surface during or after the manufacture of this metal part.

[0009] The energy of the laser beam is then absorbed by the unwanted elements, which heat up instantly. This then leads to the evaporation or sublimation of these unwanted elements (depending on their nature). In addition, the substrate also absorbs this energy to a greater or lesser extent and it is then possible to modify its surface, in particular to modify the texture of the surface (in addition to cleaning the substrate).

[0010] This laser beam treatment of surfaces is particularly interesting to implement before a bonding process because removing unwanted elements and texturing the surface in a controlled and repeatable manner ensures effective adhesion during the bonding process.

[0011] However, laser treatment may present defects in the homogeneity of surface treatment due to the fact that this treatment is based on a laser-material interaction dependent on the state of the metal surface to be treated, and in particular on the brightness of the material included in this surface.

[0012] More particularly, in the case of total or partial reflection, the reflected part of the laser beam is not absorbed by the undesirable elements, which no longer heat up and are therefore no longer eliminated. Furthermore, the substrate cannot absorb enough energy to be textured. This therefore degrades the surface preparation, and risks causing poor adhesion during the bonding process.

[0013] In addition, this laser treatment leads to the formation of a layer of material called "heat-affected zone" (or HAZ) whose microstructure and mechanical properties have changed due to the rapid succession of heating and cooling phenomena with each laser pulse. This layer of HAZ material then corresponds to a weakened area of ​​the surface. The thickness of this layer of HAZ material varies in particular depending on the parameters of the laser treatment applied. This weakening can in particular lead to a degradation of the fatigue resistance of this layer of material. Summary of the invention

[0014] The present invention then proposes to improve the treatment, by laser beam, of a metal surface of an aircraft part by ensuring homogeneity and ro- bust of this surface treatment.

[0015] One aspect of the invention thus relates to a method of treating a surface of an aircraft part, the surface comprising a metallic material, the method comprising steps of:

[0016] - mattifying the surface of the aircraft part, and

[0017] - treatment of the matte surface of the aircraft part by application of a beam laser.

[0018] Thus, advantageously according to the invention, the implementation of a step of mattifying the surface of the aircraft part before the step of treatment by the laser beam makes it possible to remove any shine from this surface, that is to say to make it matt. Thus, the step of treatment by the laser beam is improved and made more robust and homogeneous because the risks of reflection of the laser beam on the surface are greatly reduced or even eliminated.

[0019] The implementation of this mattification step promotes better absorption of the laser beam during this treatment step. Thanks to this mattification step, the surface treatment is made more robust. It is therefore possible, subsequently, to carry out a treatment of the surface by laser beam with less energy than in the case of a treatment on a surface that has not been previously mattified.

[0020] This lower energy treatment then makes it possible to limit the thickness of the layer of material known as the “heat-affected zone” (or HAZ), the microstructure and mechanical properties of which have changed due to the laser beam treatment. This then allows an improvement in the fatigue resistance of this layer of material (or, in other words, to limit any fatigue reductions in the aircraft part concerned).

[0021] As a result, the surface properties of the aircraft part are improved before post-treatment processes are carried out. In particular, the robustness of the bonding process (when assembling parts together) is significantly improved, with improved adhesion and mechanical strength in bonding.

[0022] In addition to the characteristics which have just been mentioned in the preceding paragraph, the treatment method according to one aspect of the invention may have one or more complementary characteristics among the following, considered individually or according to all technically possible combinations:

[0023] - the surface mattification step is implemented in such a way that said surface of the aircraft part has a reflection coefficient less than or equal to 30%;

[0024] - the step of mattifying the surface comprises a step of sandblasting the surface of the aircraft part, from an abrasive element;

[0025] - the abrasive element has a hardness value greater than a hardness value of the metallic material included in the surface of the aircraft part;

[0026] - the abrasive element comprises a corundum sand;

[0027] - the diameter of the abrasive element is between 40 and 200 micrometers;

[0028] - during the sandblasting step, the abrasive element is applied to the surface of the part aircraft with a predetermined pressure less than 3 bars;

[0029] - the mattifying step comprises a step of applying a solution to the surface of the aircraft part, the solution comprising caustic soda;

[0030] - the mattification step comprises a sulfo-nitro-ferric stripping step of the surface of the aircraft part;

[0031] - the mattifying step comprises a step of sanding the surface of the part aircraft from a sanding pad;

[0032] - the laser beam is emitted by a nanosecond laser source;

[0033] - the laser beam is emitted by a picosecond laser source;

[0034] - the laser beam is emitted by a femtosecond laser source;

[0035] - the laser beam has a fluence of less than 30 Joules per square centimeter;

[0036] - prior to the mattification step, a cleaning step is provided for the surface of the aircraft part from a cleaning element;

[0037] - the step of cleaning the surface comprises a step of degreasing the surface of the aircraft part;

[0038] - the cleaning element comprises a detergent degreaser;

[0039] - the cleaning element comprises a solvent;

[0040] - the cleaning element comprises isopropanol;

[0041] - the cleaning element comprises acetone; and

[0042] - between the mattification step and the treatment step, another step of cleaning the matte surface of the aircraft part, the other cleaning step being carried out from another cleaning element.

[0043] The invention and its various applications will be better understood upon reading the following description and examining the accompanying figures. BRIEF DESCRIPTION OF THE FIGURES

[0044] Other characteristics and advantages of the invention will appear on reading the description, which can be read in conjunction with the figures. These figures are presented for information purposes only and in no way limit the invention.

[0045] [Fig.l] shows, in schematic form, an aircraft part in the context of the present invention,

[0046] [Fig. 2] represents, in the form of a flowchart, an example of a method for treating a surface of an aircraft part in accordance with the invention,

[0047] [Fig. 3a] represents an image acquired by optical microscopy of a microscopic section of the surface of the aircraft part within the framework of the invention,

[0048] [Fig.3b] represents an image acquired by optical microscopy of a microscopic section of the surface of the aircraft part in the context of conventional laser beam treatment,

[0049] [Fig.4a] illustrates the results of rupture of assembled parts after tests relating to simple shear in the case of bonded assemblies within the framework of the invention, and

[0050] [Fig.4b] illustrates the results of rupture of assembled parts after simple shear tests in the case of assemblies bonded in the context of conventional laser beam treatment. DETAILED DESCRIPTION

[0051] The present invention is placed in the context of the manufacture of assembled parts for an aircraft engine. More particularly, the invention aims to provide an efficient and homogeneous treatment of a surface of an aircraft part, so as to best prepare the surface for subsequent assembly processes. These subsequent assembly processes are, for example, gluing or application of a coating (or paint).

[0052] The aircraft is for example an airplane or a helicopter. The aircraft parts concerned in the present invention are for example the different elements included in an aircraft engine. These are for example outlet guide vanes (or OGV for "Outlet Guided Vanes") of the LEAP engine (before bonding of the cowl) or vanes within the framework of the FAN RISE program ("Revolutionary Innovation for Sustainable Engine").

[0053] The present invention is more particularly placed in the context of a treatment of the surface of an aircraft part involving the use of a laser beam. It therefore aims to improve the condition of the surface of the aircraft part so that the efficiency of the treatment involving the use of the laser beam is also improved.

[0054] [Fig. 1] shows, in schematic form, an aircraft part 1 in the context of the present invention (in particular the form shown is not limiting). This aircraft part 1 comprises a core part 2 and an outer layer 3 positioned on an outer part of the core part 2. The outer layer 3 is therefore a part of the aircraft part 1 directly in contact with the surrounding outside air.

[0055] The aircraft part 1 here comprises a metallic material. This metallic material comprises, for example, aluminum. Preferably, it is an aluminum alloy. For example, this metallic material comprises an aluminum alloy of grade 2219.

[0056] In the present description, the “surface” of the aircraft part 1 corresponds to the external face of this aircraft part 1, that is to say to the part of the aircraft part 1 in direct contact with the surrounding external air. In [Fig.l], the surface S of the aircraft part 1 therefore corresponds to an external face of the external layer 3.

[0057] As the aircraft part 1 comprises a metallic material, the same is true for the surface S of the aircraft part 1 (which therefore also comprises this metallic material). According to what has been presented previously, the surface S of the aircraft part comprises, for example, aluminum. Preferably, it comprises an aluminum alloy. This is, for example, an aluminum alloy of grade 2219.

[0058] As shown in [Fig. 1], in the context of the present invention, the aircraft part 1 (and more particularly the surface S of the aircraft part 1) is for example subjected to a laser beam 102. This laser beam 102 is emitted by a laser source 100. Preferably, in the present invention, the laser source 100 is a nanosecond laser source (i.e. the laser source generates light pulses with pulse durations ranging from one to a few hundred nanoseconds). For example, the pulse durations may be between 100 and 300 nanoseconds.

[0059] Alternatively, the laser source may be a picosecond laser source (i.e., it generates light pulses with pulse durations ranging from one to a few tens of picoseconds). Alternatively, the laser source may be a femtosecond laser source (i.e., it generates light pulses with pulse durations ranging from one to a few tens of femtoseconds).

[0060] Preferably, the wavelength of the laser beam is for example 1064 nanometers (nm).

[0061] Generally speaking, when the treatment targets a metallic material, the wavelength of the laser beam is located, for example, in the infrared range close to the visible range (for example with a YAG source with a wavelength of the order of 1060-1070 nm).

[0062] When the treatment targets an organic material, the wavelength of the laser beam is, for example, in the ultraviolet range (for example with a tripled YaG source with a wavelength of the order of 350-360 nm).

[0063] Here, the fluence (i.e. the amount of energy per unit area) associated with the laser beam 102 is less than 30 Joules per square centimeter (J.cm2). Preferably, this fluence is less than 20 J.cm 2. This fluence may for example be less than 15 J.cm 2.

[0064] The laser beam 102 is used here to implement a treatment on the aircraft part 1. More particularly, this treatment concerns the surface S of the aircraft part in order to best prepare it for subsequent assembly processes.

[0065] However, given its metallic composition, the surface S of the aircraft part 1 may, for example, be shiny. This shiny appearance may hinder the proper progress of the treatment using the laser beam due to various reverberations and reflections. In the present description, the term “shiny surface” means a surface whose associated (specular) reflection coefficient is greater than 70%.

[0066] The present invention therefore relates to a method for treating the surface S making it possible to reduce or even eliminate the shiny character of the surface S of the aircraft part 1 in order to limit the reflections of the laser beam on the surface S (and therefore to allow better efficiency in the treatment of the surface S).

[0067] [Fig.2] is a flowchart representing an example of a method for processing the surface S of aircraft part 1.

[0068] It should be noted that the aircraft part 1 is manufactured prior to the implementation of the treatment method in accordance with the invention.

[0069] As shown in [Fig.2], the treatment method then begins with a step E2 of providing the aircraft part 1. This aircraft part 1 is for example positioned in a support or in a chamber in which it will undergo the different steps of the treatment method. The aircraft part 1 is positioned in such a way that the surface S of the aircraft part 1 is a free and accessible surface (i.e. it is not in contact with the support for example).

[0070] The method continues with a step E4 of cleaning the surface S of the aircraft part 1. As can be seen in [Fig. 2], this cleaning step E4 is optional and can be omitted. This cleaning step E4 aims to eliminate certain contaminations which may be present on the surface S of the aircraft part. In particular, it makes it possible to guarantee complete cleaning of the contaminations before the following steps of the method (in particular the mattifying step E6 described below). This cleaning is carried out by applying a cleaning element to the surface S of the aircraft part 1.

[0071] Preferably here, the cleaning step E4 is a degreasing step. In other words, this step aims to remove any oils or greases that are present on the surface S of the aircraft part 1.

[0072] In practice, the cleaning element comprises, for example, a detergent degreaser. This cleaning element is particularly advantageous for effectively removing contamination from the surface S, such as mineral oil films or traces of grease. It is, for example, a degreaser of the Bonderite® C-AK 5948DPM type.

[0073] Alternatively, the cleaning element may comprise a solvent. The cleaning element may, for example, comprise isopropanol or acetone. Preferably, the application of the solvent is carried out via a white (and clean) woven element.

[0074] As indicated previously, this step E4 is optional. In the case where it is not implemented, step E2 is directly followed by step E6.

[0075] Then, as can be seen in [Fig.2], the treatment method continues at step E6. This step E6 corresponds to a step of mattifying the surface S of the aircraft part 1.

[0076] In the present description, the term “mattification” means a process making it possible to reduce or even eliminate the shiny character of the surface S. It is therefore a question of making the surface S matt. In practice, a surface is said to be matt when the associated reflection coefficient is less than 30%.

[0077] In other words, the mattification step E6 aims to reduce the reflection coefficient of the surface S of the aircraft part 1 so as to make this surface S matt.

[0078] In practice, the mattifying step E6 comprises, for example, a sandblasting step of the surface S of the aircraft part using an abrasive element. By “sandblasting” is meant here a process which consists of stripping the surface S of the aircraft part 1 using a jet of the abrasive element projected by compressed air. The abrasive element is therefore here projected by compressed air towards the external layer 3 of the aircraft part 1.

[0079] The abrasive element has a hardness value greater than a hardness value of the metallic material included in the surface S of the aircraft part 1. For example, the hardness value of the abrasive element is 20% greater than the hardness value of the metallic material included in the surface S of the aircraft part 1. Such a hardness value makes it possible to ensure that the contaminations present on the surface S (for example in the outer layer 3) are removed. This also results in abrasion of the surface S (with a modification of the roughness). These advantages are reinforced when the cleaning step E4 (optional) is implemented.

[0080] The abrasive element is for example a corundum sand, preferably a white corundum sand.

[0081] Here, the abrasive element has a diameter of between 40 and 200 micrometers (pm). Preferably, this diameter is between 50 and 180 pm. More preferably, the diameter of the abrasive element is less than 80 pm, so as to limit the deterioration of the surface condition (because the abrasive element modifies the roughness of the surface all the more as the diameter of this abrasive element is high). Furthermore, such diameters make it possible to limit the incrustation of undesirable elements in the surface S.

[0082] Here, the abrasive element is projected onto the surface S of the aircraft part 1 with a predetermined pressure. This predetermined pressure is less than 3 bars. Preferably, the predetermined pressure is between 0.5 and 2.5 bars. The use of such a pressure during the mattifying step makes it possible to limit the degradation of the surface S and to limit the incrustation of undesirable elements in this surface S (because this would harm the fatigue resistance of the aircraft part).

[0083] This sandblasting step is particularly advantageous because it is carried out dry, without the use of chemicals. In addition, it is very easy to implement from an industrial point of view.

[0084] At the end of step E6, the surface S of the aircraft part 1 is matt (i.e. the glossy nature of the surface S of the aircraft part has been reduced, or even eliminated). The matt surface S is denoted SMat in the following.

[0085] Optionally, as can be seen in [Fig.2], the treatment method may comprise another step E8 of cleaning the matted SMat surface (obtained at the end of step E6). This step E8 aims to eliminate any residues present on the matted SMat surface.

[0086] In a similar manner to the cleaning step E4 described previously, this other cleaning is implemented by applying another cleaning element to the matted SMat surface.

[0087] Preferably here, the cleaning step E8 is also a degreasing step.

[0088] In practice, the other cleaning element comprises, for example, a detergent degreaser. This is, for example, a degreaser of the Bonderite® C-AK 5948DPM type.

[0089] Alternatively, the other cleaning element may comprise a solvent. The other cleaning element may, for example, comprise isopropanol or acetone. Preferably, the application of the solvent is carried out via a white (and clean) woven element.

[0090] As indicated previously, this step E8 is optional. In the case where it is not implemented, step E6 is directly followed by step E10. This step E8 is particularly advantageous in the case where a sandblasting step is implemented because it makes it possible to eliminate dust due to the sandblasting step which would be present on the surface.

[0091] The treatment method therefore then comprises the step E10 of treating the surface SMat matted by the laser beam 102. This step aims to reduce or even eliminate the undesirable elements of the surface SMat matted by irradiation with the laser beam 102. This treatment step E10 also generates a texturing of the surface S (which will be favorable for a subsequent bonding process for example). The undesirable elements are for example metal oxides formed on the surface S (and forming pollution of the surface) or organic pollution (greases, oils, solvents, etc.) and which would degrade the effectiveness of a post-treatment process which would be implemented subsequently (such a post-treatment process is not the subject of the present invention and is therefore not described in detail in the present description).

[0092] In practice, this step E10 comprises a process of scanning the surface SMat matted by the laser beam 102.

[0093] As indicated previously, the fluence associated with the laser beam 102 is here less than 30 J.cm2. Preferably, this fluence is less than 20 J.cm2.

[0094] The mattifying step E6 is particularly advantageous because it makes it possible to reduce the fluence of the laser beam used for the treatment step E10. In other words, thanks to the mattifying step, the treatment step E10 here has, with a rather low fluence of the laser beam, an efficiency comparable (from a bonding point of view after laser treatment) to that of a treatment by laser beam (without the prior mattifying step) requiring a higher fluence for the laser beam. Furthermore, the mattifying step makes it possible to significantly improve the robustness of a subsequent bonding process (when assembling parts together).

[0095] Furthermore, the scanning, by the laser beam, of the matted SMat surface is controlled so that a predetermined coverage rate of the matted SMat surface is achieved. For example, if the scanning is carried out in a grid shape (in rows and columns), it is possible to define a first coverage rate in a first direction and a second coverage rate in a second direction. For example here, in the case of a matted surface comprising an aluminum alloy for example, the first coverage rate is greater than 0.5 and the second coverage rate is less than 0.3.

[0096] Thus, during this step E10, the laser beam 102 is in the form of short laser pulses (for example nanoseconds) which interact with the desirable elements so as to eliminate them (by ejection, evaporation or sublimation for example). In addition, given the diameter of the laser beam, the elimination of the undesirable elements is implemented precisely. Furthermore, following this treatment step E10, the surface is textured, which makes it possible to promote a post-treatment step, such as a bonding step for example.

[0097] Furthermore, thanks to this focused laser beam, the treatment of the matted surface is implemented in a targeted manner, without the need to mask the surrounding areas.

[0098] Advantageously according to the invention, the implementation of a step of mattifying the surface S of the aircraft part 1 before the step of treatment by the laser beam makes it possible to remove any shine from this surface S, that is to say to make it matt. Thus, the step of treatment by the laser beam is improved and made more robust and homogeneous because the risks of reflection of the laser beam on the surface S are greatly reduced or even eliminated.

[0099] The implementation of this mattification step also makes it possible to work at a lower fluence for the laser beam during the treatment step because it promotes better absorption of the laser beam during this treatment step. Thanks to this mattification step, the surface treatment is made more robust. It is therefore possible, then, to carry out a treatment of the surface by laser beam with less energy than in the case of treatment on a surface that has not been previously mattified.

[0100] In addition, this lower energy treatment also makes it possible to limit the thickness of the layer of material known as the “heat-affected zone” (or HAZ) whose microstructure and mechanical properties have changed due to the laser treatment. This also makes it possible to reduce the quantity of material ejected during treatment by the laser beam. Finally, this allows an improvement in the fatigue resistance of this layer of material or of the aircraft part in general (or, in other words, it makes it possible to limit any fatigue reductions in the aircraft part concerned).

[0101] As a result, the surface properties of the aircraft part are improved before the implementation of post-treatment processes. In particular, the robustness of the bonding process (when assembling parts together) is significantly improved, with improved adhesion and mechanical strength in bonding.

[0102] Alternatively, the mattifying step may comprise a step of applying a solution to the surface S of the aircraft part. This solution comprises, for example, caustic soda. In practice, this variant may be implemented by immersing the surface in a chemical bath based on caustic soda.

[0103] As a further variant, the mattifying step may comprise a sulfo-nitro-ferric stripping step of the surface S of the aircraft part 1.

[0104] As a further variant, the mattifying step comprises a step of sanding the surface S of the aircraft part using a sanding support. The sanding support is, for example, a paper comprising P320 grain silicon carbide.

[0105] As a further variant, the mattifying step may comprise a step of brushing the surface S of the aircraft part 1.

[0106] Variants involving a sanding step or a brushing step are advantageous because they do not require the use of chemical processes (unlike steps involving the application of a solution or stripping).

[0107] Experimental results:

[0108] Figures 3a and 3b represent images acquired by optical microscopy of microscopic sections of the surface S of the aircraft part 1. [Fig.3a] corresponds to the configuration of the invention (i.e. with a mattification step) for a laser beam fluence of 15 J.cm2. [Fig.3b] corresponds to a conventional laser beam treatment (without a prior mattification step) for a laser beam fluence of 25 J.cm2.

[0109] From Figures 3a and 3b, it is observed that the implementation of the treatment by laser beam at lower fluence (case of [Fig.3a]) makes it possible to obtain a thickness of the layer called “heat affected zone” which is lower (less than 4 μm for [Fig.3a] and at least 6 pm for [Fig.3b]). As indicated previously, this makes it possible, on the one hand, to limit possible fatigue reductions in the aircraft part and, on the other hand, to improve the mechanical strength of the bonding.

[0110] Figures 4a and 4b illustrate the results of rupture of assembled parts after shear tests. [Fig.4a] corresponds to the configuration of the invention (i.e. with a mattifying step) for a laser beam fluence of 15 J.cm2. [Fig.4b] corresponds to a conventional laser beam treatment (without a prior mattifying step) for a laser beam fluence of 25 J.cm2.

[0111] It should be noted that shear tests are implemented according to the ISO 2243-1 standard.

[0112] Furthermore, the parts IA, IB, IC, 1D assembled here are formed from an aluminum alloy of grade 2219. The glue used for the assembly is an Aeropaste 1100 glue manufactured by the company Solvay.

[0113] In the case of [Fig.4a] (case of the invention, with mattification), it is observed that the shear failure occurs mainly at the level of the glue. On the contrary, in the case of [Fig.4b] (classic case without prior mattification), the failure (here an adhesive failure) is observed at the interface.

[0114] This then means that, within the framework of the intention (i.e. with the mattification step prior to treatment by the laser beam), better adhesion is observed between the assembled parts.

[0115] Applications:

[0116] The present invention finds a particularly advantageous application in the context of surface treatments of new or repaired aircraft engine parts, which require laser beam treatment, for example before a bonding process, a process of applying a coating or paint or before a surface texturing process.

Claims

Claims

1. Method for treating a surface (S) of an aircraft part (1), the surface (S) comprising a metallic material, the method comprising steps of: - mattifying (E6) the surface (S) of the aircraft part (1), and - treating (E10) the mattified surface (SMat) of the aircraft part (1) by applying a laser beam (102).

2. Treatment method according to claim 1, in which the step (E6) of mattifying the surface (S) is implemented in such a way that said surface (S) of the aircraft part (1) has a reflection coefficient less than or equal to 30%.

3. Treatment method according to claim 1 or 2, in which the step (E6) of mattifying the surface (S) comprises a step of sandblasting the surface (S) of the aircraft part (1), using an abrasive element.

4. A treatment method according to claim 3, wherein the abrasive element has a hardness value greater than a hardness value of the metallic material included in the surface (S) of the aircraft part (1).

5. A treatment method according to claim 3 or 4, wherein a diameter of the abrasive element is between 40 and 200 micrometers.

6. Treatment method according to any one of claims 3 to 5, wherein, during the sandblasting step, the abrasive element is applied to the surface (S) of the aircraft part (1) with a predetermined pressure of less than 3 bars.

7. A treatment method according to any one of claims 1 to 6, wherein the laser beam (102) is emitted by a nanosecond laser source.

8. A treatment method according to any one of claims 1 to 7, wherein the laser beam (102) has a fluence of less than 30 Joules per square centimeter.

9. Treatment method according to any one of claims 1 to 8, in which, prior to the mattifying step (E6), a cleaning step (E4) of the surface (S) of the aircraft part (1) is provided using a cleaning element.

10. Treatment method according to claim 9, wherein the step (E4) of cleaning the surface (S) comprises a step of degreasing the surface (S) of the aircraft part (1).

11. Treatment method according to any one of claims 1 to 10, in which, between the mattifying step (E6) and the treatment step (E10), another step (E8) of cleaning the mattified surface (S Mat) of the aircraft part (1) is provided, the other cleaning step (E8) being implemented from another cleaning element.

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