Marking coating for an oxide / oxide substrate

Abstract

Marking coating for an oxide / oxide substrate. The invention relates to a part made of oxide / oxide composite material characterized in that it comprises, on at least a portion of a free surface, a marking coating comprising: - a bonding oxide; and - a coloring agent comprising a rare earth oxide. Figure for the abstract: Fig. 2.

Description

Title of the invention: Marking coating for an oxide / oxide substrate Technical field

[0001] The present disclosure relates to a part made of oxide / oxide composite material comprising a marking coating and a method for marking a substrate made of oxide / oxide composite material. Prior art

[0002] Composite materials have good thermostructural properties, that is to say high mechanical properties which make them suitable for forming structural parts and the capacity to retain these properties at high temperatures.

[0003] Due to their better resistance to high temperatures, composite materials require less cooling. This cooling traditionally comes from an air intake in the compressor which impacts the efficiency of the turbomachine, composite materials therefore make it possible to improve engine efficiency which reduces fuel consumption.

[0004] Furthermore, the use of composite materials contributes to optimizing the performance of turbomachines, in particular by reducing the overall mass of the turbomachine, which further contributes to a reduction in fuel consumption and therefore to a significant reduction in polluting emissions.

[0005] The composite materials comprise a porous fibrous preform whose porosity is filled by a matrix.

[0006] The properties of composite materials depend on the nature of the matrix, the composition of the fiber preform but also on the nature of the weaving of the preform.

[0007] The composite materials chosen for the hot gas ejection parts are called oxide / oxide, because the composition of the fibers of the preform and that of the matrix comprise one or more oxides, for example alumina fibers and an alumina matrix.

[0008] Parts may be subject to quality requirements that make their marking necessary. This is particularly the case for aeronautical parts, for which marking makes it possible to note the history of a part, for example to identify the manufacturer, the date of manufacture or even a batch number. This marking can also be useful for forming a wear mark on a part, the evolution of which will determine the deformation actually undergone by the part, for example.

[0009] Usually, the marking of composite material parts can be done by laser engraving and / or by means of an ink.

[0010] However, none of the prior art marking methods is completely satisfactory for parts made of oxide / oxide composite material.

[0011] Indeed, laser engraving is not easily readable due to the white color of the oxide / oxide parts, and laser engraving could also cause local damage which is not necessarily desirable.

[0012] Furthermore, the high operating temperature of these parts and in particular the temperature cycles makes it difficult for conventional inks to hold, so that marking is not durable.

[0013] Thus, there remains a specific need to meet the needs of identification, tracking or marking of parts made of oxide / oxide composite materials. Statement of the invention

[0014] The invention aims precisely to meet this need.

[0015] For this purpose, it proposes a part made of oxide / oxide composite material characterized in that it comprises on at least part of a free surface a marking coating comprising: - a bonding oxide; and - a coloring agent comprising a rare earth oxide.

[0016] This embodiment provides a marking solution for parts made of oxide / oxide composite material which is easily readable on the one hand, and which also has excellent adhesion, which it also retains during temperature cycling.

[0017] In particular, the bonding oxide ensures excellent resistance of the marking coating despite the temperature and humidity conditions that the marking coating may encounter during the life of the composite material part.

[0018] Furthermore, the marking coating does not damage the coated area of ​​the part in any way, unlike, for example, etching marking as envisaged in the prior art.

[0019] The coloring agent is understood to be having a color different from the part made of oxide / oxide composite material. The “different color” within the meaning of the invention can be understood to be in the visible light spectrum or under infrared or ultraviolet stimulation.

[0020] Preferably, the color difference is appreciable by the human eye.

[0021] The marking coating has, thanks to the bonding oxide, excellent compatibility of the oxide / oxide composite material part.

[0022] The coloring agent of the marking coating provides the marking function, giving the coating a color different from the composite material part.

[0023] The bonding oxide may be chosen from any oxide, compatible with the substrate and allowing excellent adhesion of the coating to the substrate.

[0024] In one embodiment, the bonding oxide may be selected from aluminum oxide A12O3, zirconium oxide ZrO2 or silicon oxide SiO2.

[0025] The particular choice of these oxides makes it possible to ensure a coefficient of thermal expansion for the marking coating very close to the part in oxide / oxide composite material.

[0026] This ensures excellent resistance of the marking coating during use of the part and in particular when the substrate is used for applications at high temperatures, for example above 500°C, or even between 500°C and 800°C.

[0027] The coloring agent is chosen from rare earth oxides.

[0028] Rare earths are understood in the application in the usual chemical sense as the elements including yttrium, scandium and all the elements of the lanthanide family.

[0029] In one embodiment, the coloring agent is selected from praseodymium oxide (Pr6On), terbium oxide (Tb4O7), holmium oxide (Ho2O3), neodymium oxide (Nd2O3), erbium oxide (Er2O3) or thulium oxide (Tm2O3).

[0030] These oxides all allow excellent coloring and can be chosen according to the marking needs.

[0031] In particular, praseodymium oxide (Pr6On) allows a black coloration, terbium oxide (Tb4O7) a brown coloration, holmium oxide (Ho2O3) a pink coloration and fluorescent properties, neodymium oxide (Nd2O3) a blue coloration, erbium oxide (Er2O3) a pink coloration and thulium oxide (Tm2O3) a blue coloration.

[0032] In one embodiment, the marking coating comprises a content greater than or equal to 25% by mass of the bonding oxide relative to the total weight of the marking coating.

[0033] For example, the marking coating may comprise a content of between 25% and 85% by mass, or even between 25% and 95% by mass of the bonding oxide relative to the total weight of the marking coating.

[0034] These two embodiments make it possible to ensure, on the one hand, excellent resistance of the marking coating and also very good coloring of the marking coating.

[0035] In one embodiment, the marking coating may comprise a content of between 5.0% and 35% by mass of the rare earth oxide relative to the total weight of the marking coating.

[0036] In one embodiment, the marking coating has a thickness less than or equal to 500 pm, for example between 100 pm and 200 pm, or even between 125 pm and 175 pm.

[0037] Such a thickness in fact makes it possible to ensure that the marking does not affect the mechanical properties of the part. In particular, such a thickness is lower than the acceptable tolerances for the surface condition of a part made of oxide / oxide composite material, in particular for aeronautical parts.

[0038] In one embodiment, the part may be chosen from a rear body part of an aeronautical turbomachine, a combustion chamber of an aeronautical turbomachine, an aeronautical nacelle nozzle, a ring sector of an aeronautical turbomachine.

[0039] Such parts in fact conventionally comprise oxide / oxide composite materials, and can be marked using the parts of the invention.

[0040] According to another of its aspects, the invention relates to a method of forming a marking coating on at least a portion of a surface of a substrate made of oxide / oxide composite material comprising at least: - a step of applying a marking composition comprising a solvent to said substrate; and - a step of removing the solvent from the marking composition, the method being characterized in that the marking composition comprises at least: - a bonding oxide; - a coloring agent comprising a rare earth oxide; and - a solvent.

[0041] Such a method makes it possible to ensure excellent deposition of the marking coating on the substrate.

[0042] In particular, this makes it possible to ensure precise and thin deposition by means of a marking composition in the form of a suspension, which can be applied simply.

[0043] In one embodiment, the binding oxide is present in the marking composition in a mass content of between 10% and 50% relative to the total weight of the marking composition.

[0044] It has in fact been found that these contents allow optimal adhesion of the coating to the oxide / oxide composite material substrate.

[0045] In one embodiment, the coloring agent comprising a rare earth oxide is present in the marking composition in a mass content of between 3.0% and 15% relative to the total weight of the marking composition.

[0046] This embodiment allows for excellent coloring of the marking coating. In particular, the range of values ​​allows for more or less uniform coatings. less dark, while the choice of a particular rare earth oxide allows the color of the marking coating to be chosen.

[0047] In one embodiment, the step of applying the marking composition can be carried out by deposition with a brush or by projection, for example with a spray gun.

[0048] In one embodiment, the step of applying the marking composition may be preceded by a step of providing a mask.

[0049] This embodiment makes it possible to produce precise inscription on the substrate made of oxide / oxide composite material.

[0050] In one embodiment, the mask may be made of plastic, for example prepared by additive manufacturing.

[0051] Such a mask can have the form of alphanumeric inscription, or even the form of a QR code.

[0052] In one embodiment, the solvent is water.

[0053] In one embodiment, the solvent removal step may be a step evaporation of the solvent, for example carried out at a temperature greater than or equal to 100°C, or even greater than or equal to 110°C.

[0054] Such a temperature in fact allows very good elimination of the solvent, in particular when the solvent is water.

[0055] Alternatively, solvent removal can be achieved by exposure to open air. This simplifies the process, as there is no need for an active drying step to remove the solvent.

[0056] In one embodiment, the marking composition further comprises a dispersing agent in a mass content of less than or equal to 2%, for example between 0.1% and 2.0%.

[0057] This embodiment makes it possible in particular to ensure excellent dispersion of the coloring agent in the marking composition, that is to say that it avoids agglomerates of material in the solution.

[0058] For example, the dispersing agent may be nitric acid.

[0059] In one embodiment, the step of removing the solvent also removes the dispersing agent.

[0060] In one embodiment, the composition may further comprise a binder, for example polyvinyl alcohol (also known as PVA for the English acronym polyviny-lalcohol).

[0061] If present, such a binder may be present in a content of between 0.1% and 5.0%.

[0062] Such a binder makes it possible to ensure the mechanical strength of the marking composition.

[0063] Preferably, the binder can be removed during a heat treatment step.

[0064] According to another of its aspects, the invention relates to an aircraft equipped with a part as described above. Brief description of the drawings

[0065] [Fig.l] [Fig.l] represents a first step of a method in one embodiment.

[0066] [Fig.2] [Fig.2] represents a second step of a method in a mode of realization lization.

[0067] [Fig.3] [Fig.3] represents a third step of a method in a mode of realization lization.

[0068] [Fig.4] [Fig.4] represents photographs of results obtained in the examples. Description of the embodiments

[0069] The invention is now described by means of figures, present for descriptive purposes to illustrate certain embodiments of the invention and which should not be interpreted as limiting the latter.

[0070] [Fig.l] represents a first step of a method of forming a marking coating on a substrate 10 made of oxide / oxide composite material.

[0071] The oxide / oxide composite material of a substrate 10 is a material known as such.

[0072] For example, the fibrous reinforcement of such an oxide / oxide composite material may comprise fibers selected from alumina fibers, silica fibers, zirconia fibers, or a mixture of two or more of the above compounds.

[0073] For example, the matrix of such an oxide / oxide composite material may comprise alumina, silica, mullite or a mixture of several of the above compounds.

[0074] The first step of the method described in [Fig.l] comprises the arrangement of a mask 20 on said substrate 10 made of oxide / oxide composite material.

[0075] The mask 20 comprises recesses 21 corresponding to the locations where the coating is to be formed. In other words, the mask 20 acts as a stencil for the coating that is to be formed.

[0076] In one embodiment, the marking coating may be in direct contact with the substrate, i.e. there is no intermediate layer between the substrate made of oxide / oxide composite material and the marking coating.

[0077] In the example shown, the recesses 21 of the mask 20 represent alphanumeric characters.

[0078] However, one could imagine that the recesses 21 form characteristic shapes or even a bar code or a QR code for example.

[0079] [Fig.2] schematically represents a step of application of the composition of marking comprising at least one solvent, one binding oxide and one coloring agent on the substrate 10.

[0080] In the embodiment shown, the composition is applied by projection.

[0081] For example, the marking composition may be placed in a pressurized container 40 having an outlet nozzle for forming a dispersion 41 of the marking composition.

[0082] Other methods of applying the composition are conceivable, for example by brush or by other projection methods, for example by gun.

[0083] The dispersion 41 of the marking composition is applied indifferently to the mark 20 and its recesses 21. Nevertheless, the presence of the mask 20 prevents the dispersion 41 of the marking composition from reaching the substrate 10, and the composition is therefore only deposited on the surface of the substrate 10 opposite the recesses 21 of the mask 20.

[0084] After removal of the mask and as shown in [Fig.3], the marking composition can form a marking coating 11 which marks the substrate only where desired, i.e. in the recesses 21 of the mask 20.

[0085] In one embodiment, the mask is removed and the marking composition dried so that the solvent evaporates from the marking composition to form the marking coating 11 on the substrate 10.

[0086] In the marking coating 11 thus formed, the bonding oxide ensures excellent cohesion between the substrate 10 and the marking coating 11 and the coloring agent makes it possible to ensure a contrasting coloring, not shown with the white color of the oxide / oxide substrate.

[0087] Alternatively, the drying of the marking composition can be carried out before the mask 20 is removed from the substrate 10.

[0088] In one embodiment, the bonding oxide is an aluminum oxide, for example alumina (A12O3).

[0089] For example, such a bonding oxide may be an alumina-based ceramic adhesive known as such, for example among the commercial compounds of the Resbond ® brand marketed by the company Cotronics and in particular the products Resbond ® 901, Resbond ® 903 green, Resbond ® 903 HP, Resbond ® 908, Resbond ® 920, Resbond ® 989, Resbond ® 989F, Resbond ® 989FS and Resbond ® 940 HT.

[0090] These ceramic adhesives have the advantage of being commercially available and of exhibiting excellent compatibility with substrates made of oxide / oxide composite material.

[0091] [Fig. 3] represents the thickness e of the marking coating measured in the direction perpendicular to the surface of the coated substrate 10.

[0092] As described, this thickness is preferably less than or equal to 500 μm. A such thickness in fact makes it possible to mark the substrate 10 very distinctly, without causing too significant a variation in the surface condition.

[0093] The invention is now described by means of examples which are provided for illustrative purposes only and should not be interpreted as limiting the invention. Examples

[0094] A first marking composition was prepared and comprises by mass 236.2 grams of the Resbond 989FS adhesive, i.e. 88.7% by mass content of the composition, 10 grams of a praseodymium oxide powder (Pr6On) i.e. 3.8% by mass content of the composition, and 20 grams of water i.e. 7.5% by mass content of the composition.

[0095] A second marking composition was prepared and comprises by mass 236.2 grams of the Resbond 989FS adhesive, i.e. 82.5% by mass content of the composition, 30 grams of a praseodymium oxide powder (Pr6On) i.e. 10.5% by mass content of the composition, and 20 grams of water i.e. 7% by mass content of the composition.

[0096] A third composition was prepared and comprises 20 grams of a praseodymium oxide powder (Pr6On) or 6.3% by mass content of the composition, 143 grams of water or 44.8% by mass content of the composition, 9 grams of PVA or 2.8% by mass content of the composition, 0.7 grams of nitric acid or 2% by mass content of the composition, and 147 grams of alumina or 45.9% by mass content of the composition.

[0097] The compositions were applied by spraying onto a substrate made of oxide / oxide composite material.

[0098] The projection is carried out through a plastic mask obtained by additive manufacturing, the mask being placed on the substrate. The mask represents alphanumeric characters for the example.

[0099] The marking composition is then dried at room temperature.

[0100] It is observed that the patterns obtained with the three compositions allow excellent reading of the printed characters thanks to the mask.

[0101] [Fig.4] shows a photograph of the samples obtained on the left with the first composition and on the right with the second composition.

[0102] It is also observed that the second composition allows a darker marking than the first, as can be seen in [Fig.4].

[0103] Although not shown in the figures, it is further observed that the third composition allows a black marking of the substrate just as readable as the two shown in [Fig.4].

[0104] The surface condition of the marking coating is checked after drying by a profilometric analysis carried out using a digital microscope.

[0105] It is found that the thickness of the marking composition is at all points less than 150 μm.

[0106] The surface condition around the marking coating is also observed under a digital microscope and it is found that the latter is perfectly compatible with the tolerances practiced for an aeronautical application of the substrate.

[0107] The marking coating is then subjected to 100 heating and cooling cycles between 100°C and 650°C.

[0108] No signs of deterioration of the marking coating are observed and in particular, it is observed that the marking is not affected by the heating and cooling cycles.

Claims

Claims

1. Part made of oxide / oxide composite material characterized in that it comprises on at least part of a free surface a marking coating comprising: - a bonding oxide; and - a coloring agent comprising a rare earth oxide.

2. Part according to claim 1, in which the bonding oxide is selected from aluminum oxide (A12O3), zirconium oxide (ZrO2) or silicon oxide (SiO2).

3. Part according to one of claims 1 or 2, in which the coloring agent is chosen from praseodymium oxide (Pr6On), terbium oxide (Tb4O7), holmium oxide (Ho2O3), neodymium oxide (Nd2O3), erbium oxide (Er2O3) or thulium oxide (Tm2O3).

4. A part according to any one of claims 1 to 3, wherein the marking coating comprises a content greater than or equal to 25% by mass of the bonding oxide relative to the total weight of the marking coating.

5. A part according to any one of claims 1 to 4, wherein the marking coating comprises a content of between 5.0% and 35% by mass of the coloring agent relative to the total weight of the marking coating.

6. Part according to any one of claims 1 to 5, in which the marking coating has a thickness less than or equal to 500 pm.

7. Part according to any one of claims 1 to 6, is chosen from a rear body part of an aeronautical turbomachine, a combustion chamber of an aeronautical turbomachine, an aeronautical nacelle nozzle, a ring sector of an aeronautical turbomachine.

8. A method of forming a marking coating on at least a portion of a surface of a substrate made of oxide / oxide composite material comprising at least: - a step of applying a marking composition comprising a solvent to said substrate; and - a step of removing the solvent from the marking composition, the method being characterized in that the marking composition comprises at least: - a binding oxide; - a coloring agent comprising a rare earth oxide; and - a solvent.

9. A method according to claim 8, wherein the binding oxide is present in the marking composition in a mass content of between 10% and 50% relative to the total weight of the marking composition.

10. A method according to claim 8 or 9, wherein the coloring agent comprising a rare earth oxide is present in the marking composition in a mass content of between 3.0% and 15% relative to the total weight of the marking composition.

11. A method according to any one of claims 8 to 10, wherein the marking composition further comprises a dispersing agent in a mass content of between 0.1% and 2.0%.

12. A method according to any one of claims 8 to 11, wherein the marking composition further comprises a binder in a mass content of between 0.1% and 5.0%.

13. An aircraft comprising a part according to any one of claims 1 to 7.

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