WO2021198584A1

WO2021198584A1 - Method for depositing a coating onto a metal part and metal part obtained according to such a method

Info

Publication number: WO2021198584A1
Application number: PCT/FR2021/050471
Authority: WO
Inventors: Jean-Louis Fachinetti; Mickael Thiercelin
Original assignee: Safran Aircraft Engines
Priority date: 2020-03-30
Filing date: 2021-03-22
Publication date: 2021-10-07
Also published as: FR3108633A1; FR3108633B1; EP4127274A1

Abstract

The invention relates to a method for depositing a coating onto a metal substrate comprising depositing (200) a layer of paint onto said metal substrate, characterised in that depositing (200) the layer of paint comprises the following steps: - a step (210) of depositing a layer of a paint precursor material onto the metal substrate by anaphoresis; - a step (220) of curing the previously deposited layer of precursor material, in which step the precursor material is polymerised to form the layer of paint.

Description

Title of the invention: PROCESS FOR DEPOSITING A COATING ON A METAL PART AND A METAL PART OBTAINED BY SUCH A PROCEDURE

Technical area

The present invention relates to the general field of depositing a layer of paint on a metal part.

The present invention relates in particular to the deposition of a layer of paint on a metal part of a turbomachine, and in particular a part made of aluminum or an aluminum-based alloy, or a part made of titanium or an alloy based on titanium.

Prior art

In order to deposit a layer of paint on a metallic substrate, such as, for example, a layer of anticorrosion paint, it is known to first deposit a layer of chromic anodic oxidation in order to ensure the adhesion of the layer of paint.

However, the use of a chromic anodic oxidation layer no longer complies with the REACh regulation which regulates the use of chemicals.

As an alternative to depositing a chromic anodic oxidation layer, it is known to deposit a sulfuric anodic oxidation layer.

However, the deposition of a sulfuric anodic oxidation layer tends to increase the thickness of the final coating deposited on the substrate, and can also cause a greater fatigue reduction compared to the deposition of a sulfuric anodic oxidation layer. .

It is also known practice to improve the adhesion of the layer of paint to the metal substrate by mechanical activation of the surface to be coated with said metal substrate, for example by sandblasting, before depositing the layer of paint. However, the mechanical activation of the surface to be coated with the metal substrate can lead to the appearance of defects on the part, such as, for example, the encrustation of grains of sand in the metal substrate. In addition, the mechanical activation of the surface to be coated can lead to a reduction in fatigue caused by an increase in roughness.

Disclosure of the invention

The main aim of the present invention is therefore to provide a solution which responds to the problems described above.

According to a first aspect, the invention relates to a method for depositing a coating on a metal substrate comprising the deposit of a layer of paint on said metal substrate, characterized in that the deposit of the layer of paint comprises the following steps : a step of depositing a layer of a precursor material of the paint by anaphoresis on the metal substrate; a step of curing the layer of precursor material deposited previously in which the precursor material is polymerized to form the layer of paint.

Such a process makes it possible to deposit a layer of paint on a metallic substrate while ensuring good adhesion of the layer of paint on the metallic substrate. This is mainly due to the formation of an oxide layer on the surface of the metal substrate during the anaphoresis deposition process. In addition, the metal oxide layer, in combination with the paint layer, provides good corrosion resistance. The performance of such a solution is notably superior to that of the solution of the state of the art in which the metal substrate has been mechanically activated before the deposition of the paint layer.

According to one possible characteristic, the method comprises a step of depositing a finishing layer which is deposited on the paint layer.

According to one possible characteristic, the layer of precursor material is deposited with a thickness of between 1 and 60 μm, and preferably between 5 and 50 μm. According to one possible characteristic, the step of depositing the layer of the precursor material of the paint is carried out with an anaphoresis bath which comprises a temperature between 20 ° C and 80 ° C. Preferably, the temperature of the anaphoresis bath is between 20 ° C and 50 ° C.

According to one possible characteristic, the step of depositing the layer of the precursor material of the paint is carried out with a deposition voltage of between 50 and 350V. Preferably, the deposition voltage is between 100 and 280V.

According to one possible characteristic, the step of baking the layer of precursor material is carried out at a baking temperature of between 50 ° C and 200 ° C. Preferably, the cooking temperature is between 80 ° C and 150 ° C.

According to one possible characteristic, the step of baking the layer of precursor material is carried out for a baking time of between 15 minutes and 3 hours. Preferably, the cooking time is between 30 minutes and 2 hours.

According to one possible characteristic, the method comprises a step of cleaning the metal substrate before depositing the paint layer.

According to one possible characteristic, the cleaning step comprises the following sub-steps:

- a sub-step of degreasing the metal substrate;

a sub-step of pickling the metal substrate carried out after the sub-step of degreasing.

According to one possible characteristic, the metal substrate is made of aluminum, or an aluminum-based alloy, or titanium, or a titanium-based alloy.

According to one possible characteristic, the paint layer is an epoxy paint layer.

According to a second aspect, the invention relates to a turbomachine part obtained by the method according to any one of the preceding characteristics, in which the part comprises a metal substrate on which a layer of paint is deposited, a layer of metal oxides. of the metal substrate being formed between the metal substrate and the paint layer. According to one possible characteristic, a finishing layer is deposited on the paint layer.

According to one possible characteristic, the part is an angular sector of a bladed disc.

According to a third aspect, the invention relates to a turbomachine comprising a part according to any one of the preceding characteristics.

The invention also relates to a method of manufacturing a turbomachine comprising (i) a method of depositing a layer of paint on a metal substrate as described above so as to obtain a turbomachine part, and (ii) the mounting the turbomachine part thus obtained to at least one other element so as to obtain the turbomachine.

Brief description of the drawings

Other characteristics and advantages of the present invention will emerge from the description given below, with reference to the appended drawings which illustrate an exemplary embodiment thereof without any limiting nature.

[Fig. 1] Figure 1 schematically shows an example of a part obtained by the coating deposition process in which the part is an angular sector of a bladed disc.

[Fig. 2] Figure 2 schematically shows a sectional view of the part on which the paint layer has been deposited according to one possible embodiment.

[Fig. 3] Figure 3 shows schematically the different steps of a process for depositing a coating on a metal part according to a possible implementation

[Fig. 4] FIG. 4 schematically represents the deposition by anaphoresis of a precursor material of a layer of paint on the part on which the coating is to be deposited. Description of the embodiments

The present invention relates to the deposition of a coating on a metal part 1 of an aircraft turbomachine. The part 1 can for example be an angular sector of a bladed disc, as illustrated in FIG. 1. However, the invention can be used on other parts of a turbomachine which can be coated with a protective coating. , in particular to protect them from corrosion.

The invention is particularly advantageous for a part 1 made of aluminum or titanium, or an aluminum-based alloy or titanium-based alloy. Indeed, the invention is particularly well suited to the constraints encountered during the deposition of a coating on aluminum or titanium, or on an aluminum-based alloy or on a titanium-based alloy.

The part 1 made of aluminum or titanium, or of an aluminum-based alloy or a titanium-based alloy, may be a part of a low-pressure compressor of an aircraft turbomachine, of a high-pressure compressor, or a low pressure turbine. Indeed, these metals are currently suitable for the stresses of these aircraft turbomachine parts.

As illustrated in FIGS. 2 and 3, the method of depositing a coating on a metal substrate 10 formed by the bare metal part 1 comprises the deposit 200 of a layer of paint 20 on said metal substrate 10. The deposit 200 of the paint layer 20 is produced on the bare metal substrate 10. The paint layer 20 makes it possible in particular to protect the metal substrate 10 against corrosion. The paint deposited on the metal substrate is a polymer. The paint layer 20 can advantageously be an epoxy paint layer (epoxy polymer). The paint layer 20 corresponds to a layer of anticorrosion primer paint.

The deposition 200 of the primary paint layer 20 is carried out with the following two steps:

- a step 210 of depositing a layer of a precursor material of the paint on the metal substrate 10 by anaphoresis; and

- a step 220 of baking the layer of precursor material which has been deposited during step 210, this baking step 220 being carried out so as to polymerize the precursor material and thus form the final hardened paint layer 20.

The deposited precursor material may predominantly comprise by mass (that is to say comprise at least 50% by mass, or even at least 80% by mass) an organic material. The deposited precursor material may consist essentially of an organic material.

As illustrated in FIG. 2, the deposition by anaphoresis of the precursor material of the primary paint layer 20 causes the formation of a layer of metal oxides 30 of the metal of the metal substrate 10 on the surface of said metal substrate 10. formation of the layer of metal oxides 30 occurs before the precursor material of the paint is deposited on the metal substrate 10. Thus, the layer of precursor material is deposited on the layer of metal oxides 30, and therefore the layer of paint 20 is formed on said metal oxide layer 30. The metal oxide layer 30 formed by the deposition by anaphoresis comprises a thickness which is generally less than 200 nanometers.

The layer of metal oxides 30 makes it possible on the one hand to ensure good adhesion of the paint layer 20 on the metal substrate 10, and on the other hand to ensure additional protection of the metal substrate 10 with the layer of paint 20 against corrosion.

The deposition by anaphoresis of the precursor material of the paint layer 20 is illustrated in FIG. 4. The deposition by anaphoresis is carried out with an anaphoresis deposition system 2 which comprises an anode 3 and a cathode 4 which are immersed in a bath of 'anaphoresis 5. The anaphoresis deposition system 2 also comprises a direct current generator G which imposes a voltage difference between the anode 3 and the cathode 4 in order to allow the deposition of particles 6 of the precursor material present in the bath d. anaphoresis on the anode 3. The deposition of the layer of precursor material of the paint being an anaphoresis, the metal substrate 10 is used as anode 3 in the anaphoresis deposition system 2.

In order to ensure good polymerization of the paint layer 20, the baking step 220 is carried out by heating the layer of precursor material to a cooking temperature between 50 ° C and 200 ° C. Preferably, the cooking temperature is between 80 ° C and 150 ° C. In addition, the cooking step 220 is carried out for a cooking time of between 15 minutes and 3 hours. Preferably, the cooking time is between 30 minutes and 2 hours.

The paint layer 20 formed on the metallic substrate 10 comprises a thickness between 1 and 60 µm, and preferably between 5 and 50 µm. Such a thickness is a good compromise between the thickness of the coating deposited on part 1 and the resistance to corrosion provided by the paint layer 20. Thus, the layer of precursor material deposited by anaphoresis comprises a thickness between 1 and 60. pm, and preferably between 5 and 50 pm.

In order to allow a good deposition by anaphoresis of the precursor material of the paint layer 20, the deposition is carried out with the anaphoresis bath 5 which has a temperature between 20 ° C and 80 ° C, and preferably a temperature between 20 ° C and 80 ° C. ° C and 50 ° C.

Furthermore, according to another characteristic allowing good deposition by anaphoresis of the precursor material of the paint, the generator G is configured to impose a deposition voltage which is between 50V and 350V. Preferably, the generator G imposes a deposition voltage of between 100V and 280V.

Further, in order to improve the adhesion of the paint layer 20 on the metallic substrate 10, the method comprises a step 100 of cleaning the metallic substrate 10 in which the surface of the metallic substrate on which the paint layer will be deposited. is cleaned.

According to an advantageous embodiment, the cleaning step 100 comprises the following sub-steps:

a sub-step 110 for degreasing the metal substrate 10. The sub-step 110 for degreasing can be carried out by immersing the part 1 in a degreasing bath. Degreasing can also be carried out by mechanical actions.

The part 1 is rinsed at the end of the degreasing process.

a sub-step 120 of pickling the metal substrate 10. The pickling can be carried out by chemical action, for example with an acid, or by mechanical actions, for example by sandblasting or shot blasting. A rinsing of part 1 is carried out at the end stripping. According to this embodiment, the degreasing and pickling substeps are carried out.

In addition, as illustrated in FIGS. 2 and 3, a step 300 of depositing a top coat 40 on the layer of paint 20 can be carried out after the deposit 200 of said layer of paint 20. The top coat 40 forms the outer surface of the coating deposited on the part 1. The finishing layer 40 can in particular be an anti-erosion protection layer in order to protect the paint layer 20. The finishing layer 40 can thus for example be a layer of polyurethane. Preferably, the paint layer 20 is cleaned before depositing the finishing layer 40 on said finishing layer 40. In this embodiment, the final coating deposited on the metallic substrate 10 comprises the layer of metallic oxides 30. , the paint coat 20, and the top coat 40.

Claims

[Claim 1] A method of depositing a coating on a metal substrate (10) comprising depositing a layer of paint (20) on said metal substrate (10) in order to obtain a turbomachine part in which the part comprises the metallic substrate on which the layer of paint is deposited, a layer of oxides of the metal of the metallic substrate being formed between the metallic substrate and the layer of paint, the deposition (200) of the layer of paint (20) comprising the steps of following: a step (210) of depositing a layer of a precursor material of the paint by anaphoresis on the metal substrate (10); a step (220) of curing the layer of precursor material deposited previously in which the precursor material is polymerized to form the layer of paint (20), the layer of paint corresponding to a layer of anticorrosion primer paint.

[Claim 2] The method of claim 1, wherein the method comprises a step (300) of depositing a topcoat (40) which is deposited on the paint layer (20).

[Claim 3] A method according to any of claims 1 to 2, wherein the paint layer has a thickness of between 1 and 60 µm.

[Claim 4] A method according to any one of claims 1 to 3, wherein the step (210) of depositing the layer of the precursor material of the paint is carried out with an anaphoresis bath which comprises a temperature between 20 ° C and 80 ° C.

[Claim 5] A method according to any one of claims 1 to 4, wherein the step of depositing the layer of the precursor material of the paint is carried out with a deposit voltage of between 50 and 350V.

[Claim 6] A method according to any one of claims 1 to 5, wherein the step of baking the layer of precursor material is carried out at a baking temperature between 50 ° C and 200 ° C

[Claim 7] A method according to any one of claims 1 to 6, wherein the step of baking the layer of precursor material is carried out for a baking time of between 15 minutes and 3 hours, and preferably between 30 minutes. and 2 hours.

[Claim 8] A method according to any one of claims 1 to 7, wherein the method comprises a step of cleaning the metal substrate before depositing the paint layer.

[Claim 9] The method of claim 8, wherein the cleaning step comprises the following sub-steps: a sub-step of degreasing the metal substrate; a sub-step of pickling the metal substrate carried out after the sub-step of degreasing.

[Claim 10] A method according to any one of claims 1 to 9, wherein the metal substrate is aluminum, or an aluminum-based alloy, or titanium, or a titanium-based alloy.

[Claim 11] A method according to any of claims 1 to 10, wherein the paint layer is an epoxy paint layer.

[Claim 12] Turbomachine part obtained by the method according to any one of claims 1 to 11, in which the part comprises a metallic substrate on which a layer of paint is deposited, a layer of oxides of the metal of the metallic substrate being formed between the metal substrate and the paint layer, the paint deposited being a polymer and corresponding to a layer of anticorrosion primer paint.

[Claim 13] A part according to claim 12, in which a topcoat is deposited on the layer of paint.

[Claim 14] Part according to any one of claims 12 to 13, wherein the part is an angular sector of a bladed disc.

[Claim 15] A turbomachine comprising a part according to any one of claims 12 to 14.