PROCESS FOR CONTROLLING CONFORMITY OF SEALING BY PENDING

Abstract

The invention relates to a method for controlling the quality of post-anodization sealing of a metal alloy part containing more than 2% by mass of copper, relative to the mass of the part, by penetrant testing. The invention also relates to the use of a method according to the invention, for controlling the quality of post-anodization sealing of aluminum alloy parts containing more than 2% by mass of copper, relative to the total mass of the part, intended for the aeronautical sector. Figure for abstract: None

Description

Title of the invention: METHOD FOR CONTROLLING CONFORMITY OF SEALING BY PENDING Technical field of the invention

[0001] The present invention falls within the scope of research into new methods for controlling the conformity of the sealing of an anodizing layer on a part made of a metal alloy such as aluminum or an aluminum alloy, titanium or a titanium alloy, magnesium or a magnesium alloy, containing more than 2% by mass of copper, relative to the total mass of the part, in particular in aeronautical applications. Technical background

[0002] Aluminum alloys are materials of choice for the transport industry, and more particularly for the aeronautics industry, due to their excellent mechanical properties / weight ratio and their relatively low manufacturing cost. However, these alloys are likely, depending on the environment in which they are found, to be affected by several types of localized corrosion, causing the degradation of the part and possibly leading to its shrinkage or failure. Anodizing treatments are now commonly used in the aeronautics industry, mainly to improve the corrosion resistance of parts, and therefore their service life.

[0003] As the anodizing layers have a very porous structure, when chemical and / or corrosion resistance is essential, the anodizing layer must be sealed. This implies that the aluminum oxide layer is transformed into an aluminum hydroxide complex where the pores are closed. Sealing the anodic layer therefore guarantees its durability over time as well as the ability to protect itself from pollution that may diffuse on the surface. Controlling the quality of the sealing therefore becomes a necessity.

[0004] Penetrant Testing (PT) is a non-destructive testing process widely used in aeronautics in particular. This process can reveal emerging discontinuities (cracks, fissures, etc.) on any metal alloy. This non-destructive testing (NDT) method can be used in foundries, forges and machining units.

[0005] The oxidation resistance of a metal alloy is verified by a salt spray test.

[0006] The conformity of the sealing of aluminum alloys is usually verified according to the ISO 2143 standard by a coloring test after a prior acid action. The resistance of anodic coatings to dye absorption can provide information on the quality of the seal, with the total resistance indicating that the seal is good. However, ISO 2143 does not apply to alloys with more than 2% by mass of copper, relative to the total mass of the metal or its alloy.

[0007] For example, aluminum 2219 [Al Cu6Mn] is an alloy containing between 5.8% and 6.8% by mass of copper, relative to the mass of the aluminum grade 2219.

[0008] For an alloy whose copper content is less than 2% by mass relative to the mass of the alloy, the acid action is useful for dissolving the oxide layer on the surface.

[0009] On the other hand, for alloys whose copper content is greater than 2% by mass compared to the mass of the alloy, such as for example 2219 aluminum alloys, the prior acid action reacts with the copper present in these alloys and makes the test unreliable on these series of aluminum.

[0010] The acid attack is carried out to clip the upper layer in order to carry out a check on the anodizing layer. Carrying out the test without prior acid action makes the test irrelevant because the interpretation results are in accordance with the criteria of Annex A of ISO 2143 while the part absorbs the fatty substances (cutting oil, mastics) on the surface leaving cosmetic defects on the part (cdn.standards.iteh.ai / samples / 6934 / ld04908457594128b21570a2e3b2ab79 / ISO-2143-1981.pdf).

[0011] There is therefore a real need for a reliable and effective process which makes it possible to determine the quality of post-anodization sealing of a metal alloy part containing more than 2% by mass of copper, relative to the mass of the part, by penetrant testing, without requiring prior acid action.

[0012] In particular, there is a real need for a method for controlling the quality of post-anodization sealing of a metal alloy part as described above, which makes it possible to highlight emerging discontinuities of the surface porosities type (cracks, porosities, pits, cracks, shrinkage, etc.) on any metal alloy and which applies to any type of anodization. Summary of the invention

[0013] The present invention aims precisely to meet these needs, by providing a method for controlling the quality of post-anodization sealing of a metal alloy part containing more than 2% by mass of copper, relative to the mass of the part, by penetrant testing, characterized in that it comprises at least the following steps:

[0014] 1) a penetrant having a sensitivity level of at least 3;

[0015] 2) the excess penetrant is removed by

[0016] - washing with water, the water temperature being between 10 and 38°C, or

[0017] - rinsing with a solvent such as acetone or any type of solvents qualified for sweating,

[0018] 3) at the end of step 2), an emulsifier is applied to the surface of the part hydrophilic;

[0019] 4) the excess hydrophilic emulsifier is removed by washing with water and then the part is dried with compressed air or in an oven at a temperature between 10 and 70°C;

[0020] 5) a dry powder developer is applied to the areas to be checked; and

[0021] 6) the surface of the part is examined under UV (ultraviolet) lighting at a wavelength wavelength between 100 and 400 nanometers (nm) (UV light is only between 100 and 400nm, beyond this wavelength we move into visible light known as white), to control the quality of the sealing.

[0022] Prior to step 1), the method of the invention may comprise a step of preparing the surface of the metal alloy part by degreasing and / or pickling to remove the grease, dirt and oxides present on its surface.

[0023] The method of the invention therefore makes it possible, by detecting discontinuities opening onto the surface of the part being tested in the form of fluorescent indications, to provide information on the quality of the sealing and thus on the anti-corrosion properties of the part.

[0024] The control of the sealing quality according to the method of the invention can take place on a metal alloy part anodized by different anodizing techniques known to those skilled in the art, among which we can cite OAC (Chromic Anodic Oxidation), OAD (Hard Anodic Oxidation), OAS (Sulfuric Anodic Oxidation), OAST (Sulfo-Tartaric Anodic Oxidation), OAS NG FE (New Generation Fine Thickness Anodic Sulfuric Oxidation), OAS NG (New Generation Sulfuric Anodic Oxidation), TSA (Tartaric Sulfuric Anodizing).

[0025] The control of the quality of sealing according to the method of the invention can take place on a metal alloy part sealed by different sealing techniques known to those skilled in the art, including those described in WO 2021 / 152241 or in FR 3106837.

[0026] The method of the invention can be applied to any part containing more than 2% by mass of copper, relative to the total mass of the part.

[0027] The part may be made of a metal alloy chosen from an aluminum alloy, a titanium alloy, or a magnesium alloy.

[0028] Another object of the invention is the use of a method according to the invention, for controlling the quality of post-anodization sealing of aluminum alloy parts containing more than 2% by mass of copper, relative to the total mass of the part, intended for the aeronautical sector. Brief description of the figures

[0029] Other characteristics and advantages of the invention will appear during the reading of the detailed description which follows for the understanding of which reference will be made to the appended drawings in which:

[0030] [Fig. 1] represents the examination under a UV lamp showing that the penetrant was trapped in the room (presence of fluorescent background noise) or could not penetrate (absence of fluorescent indication). Detailed description of the invention

[0031] The present invention relates to a method for controlling the quality of post-anodization sealing of a metal alloy part containing more than 2% by mass of copper, relative to the total mass of the part, by penetrant testing, characterized in that it comprises at least the following steps:

[0032] 1) a penetrant having a sensitivity level of at least 3;

[0033] 2) the excess penetrant is removed by

[0034] - washing with water, the water temperature being between 10 and 38°C, or

[0035] - rinsing with a solvent such as acetone or any type of solvents qualified for penetrant testing 3) at the end of step 2), a hydrophilic emulsifier is applied to the surface of the part;

[0036] 4) the excess hydrophilic emulsifier is removed by washing with water and then the part is dried with compressed air or in an oven at a temperature between 10 and 70°C;

[0037] 5) a dry powder developer is applied to the areas to be checked; and

[0038] 6) the surface of the part is examined under UV (ultraviolet) lighting at a wavelength wavelength between 100 and 400 nm, to control the quality of the sealing.

[0039] The objective of the penetrant is to penetrate the crevices (porosity, cracks, fissures) by capillarity.

[0040] Any type of penetrant having a sensitivity level of at least 3 may be suitable in step 1). In this respect, mention may be made of a post-emulsified penetrant, a colored penetrant or a fluorescent penetrant.

[0041] The choice of penetrant is important because it must be made according to the characteristics of the part and the dimensions of the anomalies sought. Likewise, the penetration time must be judiciously established. Note that there are 2 main families of penetrants: - washable with water or removable with a solvent; - and those called “post-emulsion” (which become washable or removable after emulsification using an emulsifier). In a particular embodiment of the invention, the penetrant is a post-emulsified penetrant.

[0042] In another more particular embodiment of the invention, the penetrant is a fluorescent post-emulsified penetrant.

[0043] In steps 2) and 3), both tap water and demineralized water can be used. In step 2), the important parameters are the temperature and pressure of the water used for washing. Thus, the water used has a temperature between 10 and 38°C and a pressure below 2.7 bar.

[0044] Prior to step 1), the method of the invention may comprise a step of preparing the surface of the metal alloy part by degreasing all the dirt likely to block the defects present on its surface.

[0045] This preliminary surface preparation step may include one or more of the following operations: - solvent degreasing, to dissolve grease present on the surface of the part. This operation can be carried out by dipping, spraying, or any other method known to those skilled in the art; - alkaline degreasing, to dissolve grease present on the surface of the part. This operation can be carried out by soaking, spraying, or any other technique known to those skilled in the art;

[0046] These steps are described in detail, for example in application WO 2013 / 117759.

[0047] Intermediate rinses, in particular with demineralized water or running water, possibly followed by drying, can be carried out between the successive steps above.

[0048] The application of the penetrant, in particular post-emulsion, in step 1) and of the hydrophilic emulsifier in step 3) can be carried out by any technique known to those skilled in the art, for example, by electrostatic spraying, by aerosol spraying, by pneumatic spraying, by brush, by immersion or by dipping.

[0049] The application of the penetrant, in particular post-emulsion, having a sensitivity of at least 3 is carried out for a period of 20 to 60 min, preferably 20 to 30 min.

[0050] The application of the hydrophilic emulsifier having an HLB (Hydrophilic-Lipophilic Balance) of between 12 and 20, is carried out for a period of 0 to 3.5 min, preferably 0 to 1 min. This period is determined by a person skilled in the art depending on the emulsifier used.

[0051] The application of a hydrophilic emulsifier makes it possible to eliminate the excess of the post-emulsion penetrant.

[0052] The penetrant has a sensitivity level of at least 3. When it is a fluorescent post-emulsion penetrant, it can be chosen from all the validated fluorescent post-emulsion penetrants of the QPL AMS2644 for aeronautics such as, for example, RC-65 Level 3 according to AMS2644 (babbco), ZL27-A (Magnaflux).

[0053] The hydrophilic emulsifier in step 4) has an HLB of between 12 and 20.

[0054] The hydrophilic emulsifier can be chosen from all the validated hydrophilic emulsifiers of the QPL AMS2644 for aeronautics such as, for example, ER83C Hydrophilic Emulsifier AMS2644 ER83-B (babbco), ZR-10C (Magnaflux). The hydrophilic emulsifier must correspond to the penetrant.

[0055] The excess of the penetrant, in particular post-emulsion made miscible with water via the hydrophilic emulsifier, can be removed by washing with running water or demineralized water.

[0056] The drying in step 4) can be carried out with compressed air at a pressure of less than 1.7 bar. According to a particular embodiment of the invention, the pressure of the compressed air is 1 bar.

[0057] The drying in step 4) can also be carried out using an oven at a temperature between 10 and 70°C.

[0058] Washing with running or demineralized water in steps 2) and 4) can be carried out by a water jet with a pressure of less than 2.7 bar. According to a particular embodiment of the invention, the pressure of the water jet is 1 bar.

[0059] The dry developer may be in powder, suspension or solution form. In one embodiment of the invention, the dry developer is in powder form and may be chosen from those validated by QPL AMS2644 for aeronautics, such as, for example, the qualified developers AMS2644, D90G (Babbco) ZP4B (Magnaflux).

[0060] The dry powder developer is applied in a thin, uniform layer, of the order of a few microns, to the areas to be controlled, revealing the metal alloy of the surface of the area to be controlled.

[0061] According to a particular embodiment of the invention, the dry powder developer in step 5) completely covers the surface of the area to be controlled.

[0062] The dry developer can be applied to the part by any technique known to those skilled in the art, for example, by simple spraying, electrostatic spraying or spraying in a mist tank.

[0063] The application of the dry powder developer is carried out for a period of 10 to 240 minutes.

[0064] The penetrant, in particular post-emulsion, having a sensitivity of at least 3 in step 1) completely covers the surface of the area to be controlled.

[0065] The amount of hydrophilic emulsifier in step 3) is diluted in water (running or demineralized) to represent a concentration ranging from 1% to 10%.

[0066] The quantity of dry powder developer in step 5) allows the surface to be completely covered.

[0067] The dry developer has a particle size with particles having a diameter of less than 30 μm.

[0068] After step 5), the part is finally examined under UV (ultraviolet) lighting with a wavelength between 280 and 400 nm, preferably 315 to 400 nm (UV-A).

[0069] In a particular embodiment, the wavelength of the UV lighting is between 350 and 400 nm.

[0070] The method of the invention makes it possible to detect very fine surface porosity making the material sensitive to external pollution.

[0071] The fluorescent post-emulsion penetrant, applied, penetrates porous surfaces, but on the contrary does not penetrate a perfectly sealed surface at all.

[0072] Observation under a UV source such as a UV lamp makes it possible to immediately see whether the penetrant has been trapped in the room (presence of fluorescent background noise) or has not been able to penetrate (absence of fluorescent indication) as shown in [Fig.l].

[0073] The method of the invention allows: - to have a non-interpretable criterion of conformity that is simple to implement; - to ensure production monitoring; - to avoid additional production costs to protect parts from sources of pollution;

[0074] to ensure the presence of protection of the parts against corrosion.

[0075] In a particular embodiment of the invention, the method applies to parts made of aluminum alloy containing more than 2% by mass of copper, relative to the mass of the part, in particular parts made of aluminum alloy of the 2xxx series, in particular chosen from the group of grades 2014, 2017, 2024, 2214, 2219, 2618, in aluminum casting alloy type AU4G, AU7G, AS9U3, in aluminum alloy resulting from processes such as additive manufacturing.

[0076] The method of the invention is of great interest in any type of industry where it is sought to improve the corrosion resistance properties of metal alloy parts, in particular aluminum or aluminum alloy parts, such as in aeronautics, automobiles, the petroleum industry, etc.

[0077] Another object of the invention is the use of a method according to the invention, to control the quality of post-anodization sealing of aluminum alloy parts containing more than 2% by mass of copper, relative to the total mass of the part, intended for the aeronautical sector.

[0078] Other advantages and characteristics of the invention will appear on reading the examples below given for illustrative purposes. EXAMPLES Example 1#:

[0079] Anodizing process followed by sealing of aluminum alloy parts

[0080] Parts made of 2219 T62 aluminum alloy are treated according to the methods described below.

[0081] Surface preparation steps for the part are first carried out successively: - alkaline degreasing, by soaking the part in a solution of TURCO 4215 NCLT between 40 and 45 grams per liter, at a temperature of 57.5°C + / - 2.5°C, for 15 minutes; - rinsing with demineralized water; - acid pickling by dipping the part in a mixture of SOCOSURF A1858 between 38% and 50% by volume, SOCOSURF A1806 between 8% and 12% by volume and SOCOSURF A1850 between 12.5% ​​and 15% by volume, all at a temperature of 50°C + / -5°C for 5 to 10 minutes; - rinse with demineralized water.

[0082] The stripped and rinsed parts are then subjected to a sulfuric anodizing process.

[0083] The operating parameters for anodizing are indicated in the table below.

[0084] [Tables 1] OAS Bath composition H2SO4 at 96% by volume: 200 - 220 g / L Bath temperature 17 + / - 2°C Thickness of the layer formed (pm) 5-15 pm

[0085] The anodized parts are then subjected to the hot water sealing process at 99+ / -1°C for 30 minutes.

[0086] Method for controlling the quality of penetrant sealing according to the invention

[0087] To assess the quality of the sealing, a penetrant testing process comprising the following steps is carried out:

[0088] 1) the surface of the part obtained at the end of the sealing process is applied described above, a post-emulsified penetrant;

[0089] 2) the excess penetrant is removed by washing;

[0090] 3) a hydrophilic emulsifier is applied;

[0091] 4) the hydrophilic emulsifier is removed by washing and then the part is dried;

[0092] 5) the part is coated with dry powder developer; and

[0093] 6) the part is examined under UV (ultraviolet) lighting.

[0094] The detailed operating conditions for each of these steps are described below. Type of penetrant testing

[0095] Type lD3a according to AMS2644 (Type 1 Fluorescent, method D Post emulsified, of sensitivity 3 with dry type “a” developer). Macro range

[0096] 1) Application of penetrating S3 post-emulsified by spraying onto the surface of the piece.

[0097] Regardless of the brand of penetrant, it must be of the post-emulsion type and of a minimum sensitivity level 3. The inventors used a ZL27-A aerosol can (a commercial reference of fluorescent penetrant product from the Magnaflux brand). It is also possible to apply it, for example, by electrostatic spraying, with a brush, or by immersion.

[0098] 2) Pre-rinse: air + water (1 bar air pressure and 1 bar water pressure):

[0099] Pre-rinsing is carried out with a jet of water + compressed air with a pressure here set at 1 bar, and with a specific hydro / pneumatic gun for non-destructive testing (NDT) penetrant testing spraying the water in a diffuse manner. This pre-rinsing eliminates excess penetrant on the surface.

[0100] 3) Application of hydrophilic emulsifier 4%: 1 min.

[0101] An emulsifier of the Magnaflux brand, reference ZR-10C, was used.

[0102] The emulsifier makes the penetrant miscible with water so that it can be removed from the surface of the part during the rinsing step.

[0103] 4) Rinsing: air + water (1 bar air pressure and 1 bar water pressure) with a water jet + compressed air with a pressure set at 1 bar, and with a specific hydro / pneumatic gun for non-destructive testing (NDT) penetrant testing, spraying the water in a diffuse manner.

[0104] 5) Application of dry developer:

[0105] A ZP-4B powder (a commercial reference of Magnaflux brand Dry Developer product) was used.

[0106] 6) Control under UV-A (> 1500pW / cm2) 10 min after application of the developer. The light from UV lamps is centered on the 365 nm wavelength (UV-A).

[0107] The UV-A control shows that the applied penetrant has not penetrated the surface of the part, which means that the surface is perfectly sealed.

[0108] This control method makes it possible to discriminate between satisfactory clogging for production and non-compliant clogging with a simple and non-interpretable criterion: absence of background noise for compliant clogging.

[0109] This process of controlling clogging by penetrant testing can be included in the following macro range: - production of the forming of the aluminum part; - activation of the entire surface of the aluminum alloy part by superficial manual sanding to remove the main contaminants (cutting oil, grease, fingerprints, etc.); - carrying out anodic oxidation surface treatment including sealing;

[0110] carrying out penetrant testing on parts for qualification work; penetrant testing on specimens for production monitoring control.

Claims

Claims

1. Method for controlling the quality of post-anodization sealing of a part made of a metal alloy chosen from an aluminum alloy, a titanium alloy, or a magnesium alloy, containing more than 2% by mass of copper, relative to the mass of the part, by penetrant testing, characterized in that it comprises at least the following steps: 1) a post-emulsified penetrant having a sensitivity level of at least 3 is applied to the surface of an anodized and sealed part; 2) the excess penetrant is removed by - washing with water, the water temperature being between 10 and 38°C, or - rinsing with a solvent such as acetone or any type of solvent qualified for penetrant testing; 3) at the end of step 2), a hydrophilic emulsifier is applied to the surface of the part; 4) the excess hydrophilic emulsifier is removed by washing with water and then the part is dried with compressed air or in an oven at a temperature between 10 and 70°C;5) a dry powder developer is applied to the areas to be checked; and 6) the surface of the part is examined under UV (ultraviolet) lighting at a wavelength between 100 and 400 nm to check the quality of the sealing.

2. A method according to claim 1, characterized in that the penetrant is a fluorescent post-emulsified penetrant.

3. Method according to one of claims 1 or 2, characterized in that the penetrant having a sensitivity of at least 3 in step 1) completely covers the surface of the area to be controlled.

4. Method according to any one of claims 1 to 3, characterized in that the metal alloy is made of aluminum alloy of the 2xxx series, in particular chosen from the group of grades 2014, 2017, 2024, 2214, 2219, 2618, of aluminum casting alloy type AU4G, AU7G, AS9U3, of aluminum alloy resulting from processes such as additive manufacturing.

5. Method according to any one of claims 1 to 4, characterized in that the hydrophilic emulsifier has an HLB (Hydrophilic-Lipophilic Balance or hydrophilic / lipophilic balance) of between 12 and 20.

6. Method according to any one of claims 1 to 5, characterized in that the amount of the hydrophilic emulsifier in step 3) is from 1% to 10% by mass, relative to the mass of the part.

7. Method according to any one of claims 1 to 6, characterized in that the dry powder developer in step 5) completely covers the surface of the area to be controlled.

8. Method according to any one of claims 1 to 7, characterized in that the washing in steps 2) and 4) is carried out by a water jet with a pressure of less than 2.7 bars.

9. Method according to any one of claims 1 to 8, characterized in that the drying in step 4) is carried out using an oven at a temperature between 10 and 70°C or with compressed air at a pressure of less than 1.7 bar.

10. Use of a post-anodization sealing method according to any one of claims 1 to 9, for controlling the quality of post-anodization sealing of aluminum alloy parts containing more than 2% by mass of copper, relative to the total mass of the part, intended for the aeronautical sector.

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