Protective thermostable hybrid bonding layer for composite substrate
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- SAFRAN SA
- Filing Date
- 2024-08-27
- Publication Date
- 2026-07-08
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Abstract
Description
Description Title of the invention: Thermostable hybrid protective bonding layer for composite substrate Technical Field
[0001] The invention relates to the field of wet surface treatment of substrates made of composite materials, in particular Organic Matrix Composite (OMC) materials. Prior art
[0002] Today, metal parts on CMO substrates are mainly produced by manufacturing forged parts that are added and bonded. However, this process presents constraints and problems with bonding and matching the parts.
[0003] To address these issues, the literature presents tests on composite substrates of deposits, mainly metallic, by different thermal spraying processes, such as cold spraying (Cold Spray) or plasma spraying of powders (APS: Atmospheric Plasma Spraying). Thermal spraying is indeed a common process on metallic aeronautical parts which allows the production of coatings, most often also metallic. The principle of thermal spraying processes such as cold spraying or plasma spraying (powder, suspension or solution (SPS) or under air (APS: Air Plasma Spraying)) or flame spraying (such as supersonic flame: HVOF (High Velocity Oxy-Fuel or Supersonic Flame Spraying)) consists of projecting at high speed particles heated to high temperature (Ze. depending on the processes, above 180°C until the particles melt).
[0004] However, in order not to alter the mechanical properties and integrity of the CMOs, they present temperature and mechanical exposure limit constraints during the process. Thus, recent attempts at thermal spray deposition on organic matrix composite substrates published in the literature all lead to almost systematic erosion of the substrate which can even lead to damage to the surface strands or, in the best case, to a deposit with very low adhesion (i.e. < 1 MPa). In fact, the use of these processes on CMO substrates mainly leads to thermal damage and erosion of the substrate due to the kinetics and the contribution of calories from the projected particles. This damage to the first CMO plies results in the exposure of the reinforcing fibers and a non-adherent coating.
[0005] Application WO2021038175 already describes a means of protecting the composite by using a hybrid underlayer obtained by sol-gel process deposited before deposition by thermal spraying, the underlayer being obtained by condensation of the organic-inorganic hybrid networks between an organoalkoxysilane and a metal alkoxide so as to create Si-OM, Si-O-Si and MOM oxide bonds within the network.
[0006] However, it is always useful to find other means of protection with greater adaptability to the substrate and the sprayed material, and custom-controlled thermomechanical or viscoelastic properties thanks to the polymer component of the hybrid undercoat. The use of hybrid materials as undercoats makes it possible to obtain custom-made viscoelastic properties (thermomechanical or mechanical in temperature) that can adapt to the thermal spraying conditions specific to these hybrid materials. The organic component of the material provides the viscoelastic properties and the macroscopic mechanical behavior and the inorganic component serves as a reinforcement to the mechanical properties by increasing them and can also allow the viscoelasticity to be adapted. Statement of the invention
[0007] The inventors surprisingly discovered that it was possible to protect the organic matrix composite using a hybrid polymer-inorganic undercoat obtained by sol-gel process whose thermomechanical or viscoelastic properties are controlled. This undercoat can be considered as a surface preparation or a bonding layer, before deposition of a subsequent layer by thermal spraying. The formulation specific to the components of the undercoat as well as its process parameters (coupling, heat treatment and shaping), make it possible to control the coupling of the polymer with an inorganic compound, and thus to control its thermomechanical properties, at the macroscopic scale, particularly the viscoelastic behavior at temperature, in order to promote the increase in thickness and the adhesion of the coating above, while avoiding damage to the CMO substrate.
[0008] This undercoat thus has 3 functions: -1 protection of the substrate, particularly in CMO, from erosion and thermal input from projected particles; -2 increase in the grip of the coating to obtain its increase in thickness: - with the substrate (interface 1) mainly thanks to chemical compatibility - and with thermal spray deposition (interface 2) mainly via mechanical anchoring coming from the viscoelastic or thermomechanical properties of the bonding layers allowing its deformation upon impact of the particles, under the appropriate spraying conditions, so that they penetrate into the sub-layer and are maintained there, and potentially from the surface roughness, and the chemical interactions linked to the formulation; -3 possession of mechanical properties adapted to improve adhesion in use between the substrate and the upper layer obtained by thermal spraying.
[0009] The proposed invention consists of several levers (materials / chemistry and processes), which can be adapted (Ze. combined or used separately) depending on the intended application and the specificities of the functional need.
[0010] Adhesion to the 2 interfaces is achieved by: - mechanical adhesion - coupled with chemical adhesion.
[0011] Control of mechanical adhesion is important and is achieved through total and / or partial embedding of the projected particles in the sub-layer, creating roughness and anchoring of the particles projected into these crevices, as well as a chemical affinity between the underlayer and the resin and the fibers of the composite and / or the product they have on the surface. It should also be noted that the chains of the hybrid polymer-inorganic material of the bonding layer penetrate between the fibers and into the network of the resin of the substrate (this is an interpenetration between the different chains / networks and fibers) during its deposition if this takes place in a liquid way. This adds mechanical adhesion to the interface 1.
[0012] The chemical composition of the undercoat also makes it possible to control, within a given range, the elasticity, ductility, rigidity, hardness and homogeneity of its mechanical properties. This makes it possible to control the phenomena leading to the increase in thickness and the adhesion of the deposit by thermal spraying.
[0013] The inventors also realized that such an undercoat could also protect other types of composites such as Ceramic Matrix Composites (CMC) or Metal Matrix Composites (MMC).
[0014] They finally realized that such an undercoat could improve adhesion to composites during other types of layer deposition such as dip-coating or spraying.
[0015] The present invention therefore relates to a method for preparing by sol-gel route a hybrid polymer-inorganic composition comprising the following steps: a- preparation of a composition comprising (al) a thermostable polymer, optionally dissolved in a solvent, such as for example an aqueous, alcohol or hydroalcoholic solvent, ketones, ethers, glycol ethers, aliphatic or aromatic hydrocarbons (a2) a metal oxide or silicon-based compound chosen from: (a2a) an organoalkoxysilane of general formula (I) R 2 m If(OR 1 ) 4-m , in which R 1 represents a Cr-C4 alkyl group, in particular methyl, ethyl or isopropyl, more particularly ethyl, m represents an integer chosen from 0, 1, 2 and 3, in particular 0 or 1, more advantageously m=0 and each R 2independently of one another represents a group selected from C6-C10 aryl, methacryl, methacryl(C1-C10 alkyl) (such as methacrylpropyl) or methacryloxy(C1-C10 alkyl) (such as methacryloxypropyl), epoxyalkyl or epoxyalkoxyalkyl in which the alkyl group is straight, branched or cyclic C1-C10 and the alkoxy group is straight or branched C1-C10 (such as glycidyl and glycidyloxy(C1-C10 alkyl) in particular glycidyloxypropyl), C2-C10 mercaptoalkyl (such as mercaptopropyl), C2-C10 aminoalkyl (such as aminopropyl), (C2-C10 aminoalkyl)amino(C2-C10 alkyl) (such as 3-[(2-aminoethyl)amino]propyl), di(C2-C10 alkylene)triamino(C2-C10 alkyl) (such as 3-[diethylenetriamino]propyl), imidazolyl-(C2-C10 alkyl) and imido-C2-C10 alkyl, isocyanate, in particular each R 2represents independently of one another a group chosen from an epoxyalkyl or epoxyalkoxyalkyl group in which the alkyl group is linear, branched or cyclic in C1-C10 and the alkoxy group is linear or branched in C1-C10 (such as glycidyl and glycidyloxy(C1-C10 alkyl) in particular glycidyloxypropyl) and aminoalkyl in C2-C10 (such as aminopropyl), the organoalkoxysilane advantageously having been previously mixed with an aqueous medium, in particular with water or a water / alcohol mixture, more particularly acidified water, with stirring for the time necessary to hydrolyze and condense the organic-inorganic hybrid network, (a2b) inorganic nanoparticles, advantageously chosen from metal oxide nanoparticles, silicon oxide nanoparticles and mixtures thereof, such as for example chosen from SiO2, ZrO2, TiO2 and mixtures thereof, in particular it is SiO2; and (a2c) a mixture of organoalkoxysilane of general formula (I) and inorganic nanoparticles; (a3) optionally a coupling agent (a4) optionally a metal alkoxide of general formula (II) M(OR 3 ) X in which R 3represents a C1-C4 alkyl group, in particular propyl or butyl, M represents a metal chosen from the group consisting of transition metals, lanthanides, phosphorus, magnesium, tin, zinc, aluminum and antimony, advantageously from the group consisting of Cu, Mn, Sn, Fe, Mg, Zn, Al, P, Sb, Zr, Ti, Hf, Ce, Nb, V and Ta, more advantageously from the group consisting of Zr, Ti, Al and Sb, even more advantageously from the group consisting of Zr, Ti and Al, more particularly the metal is identical to the metal of the subsequent coating layer, in particular deposited by projection (see step B) below) and x is an integer representing the valence of the metal, advantageously, with stirring for the time necessary to hydrolyze and condense the organic-inorganic hybrid network, in particular for a few minutes to several hours, more particularly between 15 minutes and 5 hours; (a5) optionally metal nanoparticles such as for example chosen from Ag, Al, Ti and their mixtures; b- mixing of the composition in the presence of an aqueous medium, in particular water or a water / alcohol mixture, more particularly acidified water, with stirring for the time necessary to hydrolyze and condense the organic-inorganic hybrid network c- optional heat treatment of the composition, in particular at a temperature and for a time sufficient to activate and possibly accelerate the coupling reactions between the different compounds, for example at 60°C for 48 hours.
[0016] The process according to the invention is advantageously carried out with stirring.
[0017] In a particular embodiment of the invention, the metal alkoxide of formula (II) according to the invention has previously reacted with the aqueous medium, in particular for the time necessary for the condensation of the organic-inorganic hybrid networks, before its addition to the composition.
[0018] In this application, the expressions "between ... and ..." and "from ... to ..." must be understood to include the limits unless explicitly stated otherwise.
[0019] For the purposes of the present invention, the term "thermostable polymer" means any polymer which does not chemically degrade when exposed to temperature, typically up to 200°C or to the temperature of impact of the particles on the coating during thermal projections. In particular, it is a thermoplastic polymer, more particularly chosen from polyimides and cellulosic polymers, in particular from linear polyimides and hydroxypropyl cellulose.
[0020] For the purposes of the present invention, the term "C1-C4 alkyl group" means any linear or branched alkyl group comprising from 1 to 4 carbon atoms. It may thus be a methyl, ethyl, n-propyl, iso-propyl, n-butyl, sec-butyl or tert-butyl group, preferably methyl, ethyl or iso-propyl, in particular ethyl or methyl, more particularly ethyl.
[0021] For the purposes of the present invention, the term “C1-C18 alkyl group” means any linear or branched alkyl group comprising from 1 to 18 carbon atoms. This may be methyl, ethyl, n-propyl, iso-propyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl or octadecyl, preferably methyl, ethyl or iso-propyl, in particular ethyl or methyl.
[0022] For the purposes of the present invention, the term “Ci-Ci alkyl group” means any linear or branched alkyl group comprising from 1 to 10 carbon atoms. It may thus be methyl, ethyl, n-propyl, iso-propyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl heptyl, octyl, nonyl, or decyl, preferably methyl, ethyl or propyl, in particular ethyl or propyl.
[0023] For the purposes of the present invention, the term “C2-C4 alkene group” means any alkene group of 2 to 4 carbon atoms, linear or branched, in particular the vinyl, allyl, 1-propenyl, 2-propenyl and butenyl group.
[0024] For the purposes of the present invention, the term “C2-C4 alkyne group” means any alkyne group of 2 to 4 carbon atoms, linear or branched, in particular the ethynyl, acetylenyl or propargyl group.
[0025] For the purposes of the present invention, the term "non-hydrolyzable group" means any group incapable of reacting with water to give an -OH group.
[0026] The term "C6-C10 aryl group" means, within the meaning of the present invention, one or more aromatic rings having 6 to 10 carbon atoms, which may be joined or fused. In particular, the aryl groups may be monocyclic or bicyclic groups, preferably phenyl or naphthyl.
[0027] The term "coupling agent" means any chemical product having chemical functions allowing coupling by chemical reaction creating strong covalent bonds with the polymer according to the invention and with the metal oxide-based or silicon-based compound according to the invention. This may be, for example, 3-(triethoxysilyl)propyl isocyanate.
[0028] The content of metal oxide-based or silicon-based compound (a2) in the composition according to the invention, in particular inorganic nanoparticles, is advantageously less than or equal to 50% by mass relative to the total mass of the composition, more advantageously between 0.5% and 40% by mass relative to the total mass of the composition, even more advantageously between 1% and 30% by mass relative to the total mass of the composition, in particular between 2% and 15% by mass relative to the total mass of the composition, more particularly between 5% and 10% by mass relative to the total mass of the composition.
[0029] In an advantageous embodiment, the organoalkoxysilane of general formula (I) is chosen from tetraethyl orthosilicate (TEOS: Si(OEt)4), (3-aminopropyltrialkoxysilane (R 1 O)3Si-(CH2)3-NH2, 3-(2-aminoethyl)aminopropyltrialkoxysilane (R 1O)3Si-(CH2)3-NH-(CH2)2-NH2, 3-(trialkoxysilyl)propyldiethylenetriamine (R 1 O)3Si-(CH2)3-NH-(CH2)2-NH-(CH2)2-NH2, 3-chloropropyltrialkoxysilane (R 1 O)3Si-(CH2)3CI, 3-mercaptopropyltrialkoxysilane (R 1 O)3Si-(CH2)3SH, (3-glycidoxypropyl)trialkoxysilane, (trialkoxysilyl)propyl methacrylate, Aminopropyltrialkoxysilane; organosilyl azoles of the N-(3-trialkoxysilylpropyl)-4,5-dihydroimidazole type and mixtures thereof, R 1 having the same meaning as above. In particular, it is tetraethyl orthosilicate (TEOS).
[0030] In a particularly advantageous embodiment, the metal oxide or silicon-based compound (a2) consists of inorganic nanoparticles (a2b).
[0031] The nanoparticles according to the invention may have a size, in particular the largest dimension, more particularly the diameter, even more particularly the volume average diameter D50, ranging from 2 nm to 1 pm, in particular from 10 to 500 nm, more advantageously from 100 to 300 nm, in particular 200 nm. The diameter of these particles can be measured by transmission microscopy (or TEM), X-ray diffraction and small angle X-ray scattering or light scattering.
[0032] Advantageously, the metal M of the nanoparticles is the same as that contained in the deposition of the subsequent coating layer, in particular the deposition by projection, of step B) of the method for coating a composite substrate according to the invention as described below.
[0033] In another advantageous embodiment, the metal alkoxide of formula (II) is chosen from aluminum (III) isopropoxide, titanium (IV) butoxide and zirconium (IV) propoxide.
[0034] The present invention further relates to the polymer-inorganic hybrid composition obtainable, more advantageously obtained, by the method according to the invention, in particular as described above.
[0035] The present invention further relates to a method of coating a composite substrate characterized in that it comprises the following successive steps: A- deposition of at least one layer of the polymer-inorganic hybrid composition according to the invention on a composite substrate; B- deposition of at least one subsequent coating layer, in particular by projection, on the composite substrate coated with the layer obtained in step A).
[0036] The coating method according to the invention may further comprise a step C) of recovering the coated composite substrate obtained in step B).
[0037] The substrate according to the invention is made of composite. It may advantageously be an Organic Matrix Composite (OMC), a Ceramic Matrix Composite (CMC) or a Metal Matrix Composite (MMC). In particular, the substrate is made of an organic matrix composite.
[0038] Organic matrix composite substrates are well known to those skilled in the art. They generally consist of a fibrous reinforcement densified by an organic matrix such as, for example, a thermosetting or thermoplastic resin, in particular chosen from an epoxy, polyimide, and polyurethane resin (thermosetting resin) or a PEEK (polyetheretherketone), PEKK (polyetherketoneketone), PAEK (polyaryletherketone), polyetherimide, polycarbonate, polyolefin (polyethylene or polypropylene), PVC (polyvinyl chloride) and polystyrene (thermoplastic resins), or a bismaleimide or cyanate-ester resin, more particularly an epoxy resin.
[0039] The manufacture of these substrates is well known and begins with the production of a fibrous structure which can be in different forms, such as: - two-dimensional (2D) fabric, - three-dimensional (3D) fabric obtained by 3D or multi-layer weaving, - braid, - knit, - felt, - unidirectional (UD) sheet of yarns or cables or multidirectional (nD) sheets obtained by superimposing several UD sheets in different directions and bonding the UD sheets together, for example by sewing, by chemical bonding agent or by needling. It is also possible to use a fibrous structure formed by several superimposed layers of fabric, braid, knit, felt, sheets or others, which layers are bonded together, for example by sewing, by implantation of yarns or rigid elements or by needling.The fibers constituting the fibrous structure are in particular refractory fibers, that is to say in general fibers made of carbon or polymer or glass, in particular carbon.
[0040] After possibly shaping and consolidation, the fibrous structure is then densified. Densification of the fibrous structure consists of filling the porosity of the structure, in all or part of its volume, with the material constituting the matrix. The matrix of the composite material is obtained in a manner known per se, for example by following the liquid process. The liquid process consists of impregnating the fibrous structure with a liquid resin containing a precursor of the matrix material. The precursor is usually in the form of a polymer, optionally diluted in a solvent. The fibrous structure is placed in a mold that can be sealed tightly with a housing having the shape of the final molded part. Then, the mold is closed and the resin is injected into the entire housing to impregnate the fibrous texture.The transformation of the precursor into a matrix, namely its polymerization, is carried out by heat treatment, generally by heating the mold, after removal of any solvent and crosslinking of the polymer, the preform being kept in the mold. The matrix is an organic matrix such as a thermoplastic or thermosetting resin. The organic matrix can be obtained in particular from epoxy resins, such as the high-performance epoxy resin sold under the reference PR 520 by the company CYTEC.
[0041] According to one aspect of the invention, the densification of the fiber preform can be carried out by the well-known transfer molding process known as RTM ("Resin Transfer Molding"). According to the RTM process, the fiber preform is placed in a mold having the external shape of the part to be produced. A thermosetting resin is injected into the internal space of the mold which includes the fiber preform. A pressure gradient is generally established in this internal space between the place where the resin is injected and the orifices for discharging the latter in order to control and optimize the impregnation of the preform by the resin.
[0042] The densification of the fiber preform can also be carried out, in a known manner, by gaseous means by chemical vapor infiltration of the matrix (CVI). The fiber preform corresponding to the fiber reinforcement of the substrate to be produced is placed in a furnace into which a reaction gas phase is admitted. The pressure and temperature prevailing in the furnace and the composition of the gas phase are chosen so as to allow the diffusion of the gas phase within the porosity of the preform to form the matrix by deposition, at the heart of the material in contact with the fibers, of a solid material resulting from a decomposition of a constituent of the gas phase or a reaction between several constituents, unlike the pressure and temperature conditions specific to CVD ("Chemical Vapor Deposition") processes which lead exclusively to a deposition on the surface of the material.
[0043] Ceramic matrix composite substrates are also well known to those skilled in the art. They are generally made up of a fibrous reinforcement often based on carbon fibers or silicon carbide fibers, sometimes aluminum oxide or alumina fibers (AI2O3), or mixed crystals of alumina and silicon oxide or silica (SiOz) called mullite (3AI2O3, 2SiO2), densified by a ceramic matrix such as for example a matrix based on alumina, mullite, carbon or silicon carbide.
[0044] The fibrous structure and densification can be achieved as previously indicated for organic matrix composites.
[0045] Metal matrix composite substrates are also well known to those skilled in the art. They generally consist of a fibrous reinforcement often based on ceramic fibers, for example silicon carbide, or metal fibers such as steel wires, densified by a light metal matrix such as, for example, a matrix based on aluminum, magnesium, zinc or titanium.
[0046] The fibrous structure and densification can be achieved as previously indicated for organic matrix composites.
[0047] In an advantageous embodiment of the invention, the composite substrate is a part intended for aeronautics, in particular an engine or nacelle part, more particularly a reactor or turbomachine, advantageously a fan blade, a fan casing or a guide vane (OGV: Outlet Guide Vanes).
[0048] The deposition of the polymer-inorganic hybrid layer of step A) is carried out by methods well known to those skilled in the art such as dip-coating, spray coating, drop-casting, spin-coating, spatula, film puller or brush, in particular by dipping or spraying or drop-coating.
[0049] In an advantageous embodiment of the invention, the thickness of the polymer-inorganic hybrid layer obtained in step A) is between 5 μm and 1 mm, advantageously between 50 μm and 200 μm. This thickness depends on the size of the particles and the nature of the deposition of the subsequent layer of step B) meeting a functional need (anti-erosion, defrosting: anti-icing (anti-frost), anti-lightning, anti-fire, etc.).
[0050] Step B) of depositing the subsequent coating layer of the method according to the invention can be carried out by a method well known to those skilled in the art. It can thus be a deposition step by projection of particles at high speed, such as thermal projection or projection of particles at high speeds but at room temperature (binder jetting). Advantageously, it is a thermal projection step such as cold projection or plasma projection (powder, suspension or solution (SPS) or under air (APS: air Plasma Spraying)) or flame projection (such as supersonic flame: HVOF (High Velocity Oxy-Fuel or Supersonic Flame Projection). It can also be a heat treatment in compression. It is advantageously a cold projection (coldspray), in particular low pressure. These methods are well known to those skilled in the art.
[0051] Advantageously, the subsequent coating layer of step B) is a layer of metal (pure metal or metal alloy), ceramic, cermet, metal oxides, such as alumina-titanium dioxide (AI2O3-TiO2) or reinforced or unreinforced polymer or a mixture, advantageously it is a layer of metal (pure metal or metal alloy) and / or ceramic, in particular titanium or aluminum or copper or a mixture of metals, for example a mixture of tin and copper. The particles deposited, in particular projected, during step B) of the method according to the invention are thus advantageously particles of metal (pure metal or metal alloy), ceramic, cermet, reinforced or unreinforced polymer or a mixture, in particular of metal, such as titanium or aluminum or copper or a mixture of metals, for example a mixture of tin and copper. The subsequent cermet layer according to the invention may be a layer of cermet highly loaded (preferably, above 12% by weight) in a metallic element of the Co, Ni, Cu, Al type or in an alloy of these elements, for example WC12Co, WC17Co. The subsequent metal layer according to the invention may be in Ni, Al or Ti, in a base alloy Ni, Co, Al or Ti. For example, it may be: - a Ni-based alloy, of the NiAI, NiCrAI, NiCrAIY type and, in particular, a Ni-based alloy comprising 5 to 20% by weight of AI, for example Ni5AI, NiCr-6AI; - an aluminum alloy comprising at most 12% by weight of Si; - a metallic alloy (called "resistant") based on Ni or Co heavily loaded with additional metallic elements, for example CoMoCrSi, CoNiCrAIY; - a low alloy Ti alloy such as TA6V or TI6242 or Ti[321s.
[0052] Such metals or alloys have good mechanical properties, including good ductility and therefore good shock absorption, which allows them, for example, to be used as a protective reinforcement for the substrate, particularly in CMO, especially when the substrate is the leading edge of a blade, for example a fan or rectifier blade. Aluminum, copper and zinc and Sn-Zn and Sn-Cu alloys and aluminum alloys are interesting for producing an anti-lightning layer. TiO2 and SiO2 are interesting for producing an anti-icing layer. Ti and TiN are interesting for producing an anti-erosion layer.
[0053] The thickness of the subsequent coating layer depends on its nature and function (anti-erosion, de-icing, anti-lightning, anti-fire, etc.). It can, for example, vary between 50 pm and 200 pm or even reach several mm, for example between 0.5 mm and 20 mm, or even a few cm (4-5 cm for example).
[0054] In an advantageous embodiment, the method according to the invention comprises a preliminary step alpha) of preparing the surface of the composite substrate before step A) of depositing the layer of hybrid composition according to the invention, advantageously by degreasing followed by sanding or sanding, sometimes even followed by cleaning with a solvent. This step makes it possible to improve the adhesion of the undercoat of step A) on the substrate. Step A) is therefore carried out on the composite substrate thus prepared, that is to say obtained at the end of this step.
[0055] In another advantageous embodiment, the method according to the invention comprises an intermediate step: A1) of heat treatment. This intermediate step A1), which is located between steps A) and B), is a step of heat treatment of the coated composite substrate obtained in step A), at a maximum temperature of 150°C, in particular at a temperature of 60°C then 100°C then again 150°C, advantageously for 6 hours, (in particular 3 hours at 60°C + 2 hours at 100°C + 1 hour at 150°C), step B) therefore being carried out on the substrate obtained in step A1). This heat treatment step is therefore optional and makes it possible to accelerate and control the consolidation and drying of the hybrid composition layer if necessary.
[0056] In another advantageous embodiment, the method according to the invention comprises an additional finishing step: D) after step B) or after the optional step C). This is a mechanical or chemical surface finishing step which makes it possible to obtain the final surface state required to guarantee the desired functionality. It can in particular be carried out by methods well known to those skilled in the art such as, for example, sandblasting, shot blasting, laser texturing, printing, stamping, abrasion (paper or abrasive stone), machining, chemical etching or water jet.
[0057] In a variant of the embodiment, the method according to the invention comprises an intermediate step: A2). This intermediate step A2), which is located between steps A) and B) or between the possible step A1) and step B), is a step of increasing the surface roughness of the coated composite substrate obtained in step A) or in step A1), step B) therefore being carried out on the substrate obtained in step A2). This step A2) can be carried out by a method well known to those skilled in the art such as sandblasting, laser texturing, printing, stamping, abrasion (paper or abrasive stone), machining, chemical attack or water jet. It makes it possible to improve the adhesion of the subsequent layer of step B) on the layer of hybrid composition according to the invention. This variant of the process according to the invention therefore comprises steps, alpha), A), A1), A2), B), C) and D) as described above, steps alpha), A1), C) and D) being optional.
[0058] Advantageously, the particles deposited, in particular projected, during step B) penetrate into the layer of hybrid composition according to the invention, thus creating a concentration gradient of particles embedded in said layer. Indeed, the projection conditions will place the layer of hybrid composition in a temperature range where its mechanical behavior will have a good capacity to deform under the impact of the particles deposited, in particular projected, during step B). For this, the chemical composition of the hybrid composition according to the invention as well as its drying parameters are specifically chosen to allow penetration of the deposited particles, in particular projected.In particular, the chemical precursors (polymer and metal oxide or silicon-based compound of the hybrid composition), their proportions and functions can be specifically chosen, as can the particle size of the composition.
[0059] This particle incrustation gradient will also make it possible to control the differences in expansion coefficient between the substrate and the final coating, when the part is used.
[0060] The present invention further relates to a composite substrate, in particular an organic matrix composite, coated capable of being obtained by the method according to the present invention, in particular as described above. It therefore comprises a coating consisting of at least one layer of hybrid composition according to the invention, in particular as described above, and a subsequent layer, in particular obtained by spraying, more particularly by thermal spraying, in particular as described above.
[0061] In an advantageous embodiment of the invention, the coated composite substrate is a part intended for aeronautics, in particular an engine or nacelle part, more particularly a reactor or turbomachine, advantageously a fan blade, a fan casing or a guide vane (OGV: Outlet Guide Vanes).
[0062] The thickness of the hybrid composition layer of the substrate is advantageously between 5 μm and 1 mm, advantageously between 50 μm and 200 μm. This thickness depends on the size of the particles and the nature of the deposition of the subsequent layer, in particular thermally sprayed, which meets a functional need (anti-erosion, defrosting: anti-icing, anti-lightning, anti-fire, etc.).
[0063] Advantageously, the subsequent coating layer of the substrate is a layer of metal (pure metal or metal alloy), ceramic, cermet, metal oxides, such as alumina-titanium dioxide (AI2O3-TiO2), or reinforced or unreinforced polymer or their mixture, advantageously it is a layer of metal (pure metal or metal alloy) and / or ceramic, in particular titanium or aluminum or copper or a mixture of metals, for example a mixture of tin and copper. The subsequent cermet layer according to the invention may be a layer of cermet highly loaded (preferably, above 12% by weight) in a metallic element of the Co, Ni, Cu, Al type or in an alloy of these elements, for example WC12Co, WC17Co. The subsequent metal layer according to the invention may be in Ni, Al or Ti, in a base alloy Ni, Co, Al or Ti. For example, it may be: - a Ni-based alloy, of the NiAI, NiCrAI, NiCrAIY type and, in particular, a Ni-based alloy comprising 5 to 20% by weight of AI, for example Ni5AI, NiCr-6AI; - an aluminum alloy comprising at most 12% by weight of Si; - a metallic alloy (called "resistant") based on Ni or Co heavily loaded with additional metallic elements, for example CoMoCrSi, CoNiCrAIY; - a low alloy Ti alloy such as TA6V or TI6242 or Ti 021s.
[0064] Such metals or alloys have good mechanical properties, including good ductility and therefore good shock absorption, which allows them, for example, to be used as a protective reinforcement for the substrate, particularly when the substrate is the leading edge of a blade, for example a fan or rectifier blade. Aluminum, copper and zinc and Sn-Zn and Sn-Cu alloys and aluminum alloys are interesting for producing an anti-lightning layer. TiCh and SiCh are interesting for producing an anti-icing layer. Ti and TiN are interesting for producing an anti-erosion layer.
[0065] The thickness of the subsequent coating layer depends on its nature and function (anti-erosion, de-icing, anti-lightning, anti-fire, etc.). It can, for example, vary between 50 pm and 200 pm or even reach several mm, for example between 0.5 mm and 20 mm, or even a few cm (4-5 cm for example).
[0066] The present invention further relates to the use of a hybrid composition according to the invention as an underlayer of a composite substrate, in particular an organic matrix composite, in order to protect said substrate and / or to improve the adhesion to said substrate, during the deposition of a subsequent layer, in particular by spraying, more particularly by thermal spraying. In particular, the hybrid composition, the composite substrate and / or the subsequent layer are as described above.
[0067] The use can thus be to improve the adhesion of the subsequent layer to the substrate during deposition and / or the adhesion in use between the substrate and the subsequent layer.
[0068] The invention will be better understood by reading the description of the figures and examples which follow, which are given for non-limiting information purposes. Brief description of the drawings
[0069] [Fig. 1] Figure 1 represents a representative diagram in vertical section of a composite substrate (1) coated with a layer of polymer-inorganic hybrid composition (2) and with a subsequent coating layer (3) obtained by the method of the invention.
[0070] [Fig. 2] Figure 2 represents the same diagram as that of Figure 1 in which layer (2) contains a gradient of particles (4). EXAMPLES polvimide^
[0071] Preparation of polvimide
[0072] Monomer 1: - Weigh the diamine (4,4 oxydiamine) in a three-necked flask: 2.52 g; - Add the solvent (Diethylacetamine) to the three-necked neck: 20 mL; - Wait for the monomer to completely dissolve while stirring.
[0073] Monomer 2: - Weigh the dianhydride (Pyromilic dianhydride) in a bottle: 2.78 g; - Add the solvent (Diethylacetamine) to the bottle: 20 mL; - Stir the mixture for 30 min.
[0074] Summary: - Gently add the monomer 2 dissolved in the solution; - Wait while stirring: 5 hours minimum.
[0075] Chain termination: - Add the coupling agent: 0.23 mL; - Leave stirring for 17 hours.
[0076] Preparation of the polymer-inorganic hybrid material: - Weigh the TEOS (Tetraethyl orthosilicate): 16.16 g; - Add ethanol: 8.75 g; - Add acidic water: 3.42 g - Leave to stir overnight - Take the prepared solution in a beaker: 18 g - Accelerate the agitation of the tricollar - Add the solution to the mixture of monomers 1 and 2; - Leave stirring for 2-3 hours;
[0077] Coating a composite substrate: - Apply the mixture by depositing drops on the composite substrate; - Place the coated composite substrates in the oven - TT: 3h - 60°C
[0078] HPC (hydroxypropylcellulose) dissolution: Dissolve 10% by mass of hydroxypropyl cellulose (HPC) in isopranol (IPA) with stirring and ultrasound: 5g of HPC + 50g of IPA = 63.6 mL.
[0079] Preparation of TEOS solution: Weigh the TEOS with the desired quantity (%wt) calculated according to m H pc -> 1.750g = 1.875 mL. Add water and acid.
[0080] Preparation of the polymer-inorganic hybrid material: - Add the TEOS solution to the bottle containing the dissolved cellulose. - Pass the mixture through ultrasound for 15 minutes - Place the closed bottle in the oven at 60°C for at least 24 hours.
[0081] Coating a composite substrate: - Drop casting the solution onto the substrate; - Apply heat treatment: 3h-60°C
Claims
Claims
1. A method for preparing a polymer-inorganic hybrid composition by sol-gel method, comprising the following steps: a- preparation of a composition comprising (al) a thermostable polymer, optionally dissolved in a solvent (a2) a compound based on metal oxide or based on silicon chosen from: (a2a) an organoalkoxysilane of general formula (I) R^S OR 1 )^, in which R 1 represents a CrC4 alkyl group, m represents an integer chosen from 0, 1, 2 and 3 and each R 2independently of one another represents a group selected from, a C 6 -C 8 aryl, methacryl, methacryl (C 1 -C 10 alkyl) or methacryloxy (C 1 -C 10 alkyl), epoxyalkyl or epoxyalkoxyalkyl group in which the alkyl group is linear, branched or cyclic C 1 -C 10 and the alkoxy group is C 1 -C 10 , mercapto (C 2 -C 10 alkyl), amino (C 2 -C 10 alkyl), (amino (C 2 -C 10 alkyl)amino (C 2 -C 10 alkyl), di (C 2 -C 10 alkylene) triamino (C 2 -C 10 alkyl), imidazolyl (C 2 -C 10 alkyl), isocyanate and imido (C 2 -C 10 alkyl), (a2b) inorganic nanoparticles, advantageously chosen from metal oxide nanoparticles, silicon oxide nanoparticles and mixtures thereof and (a2c) a mixture of organoalkoxysilane of general formula (I) and inorganic nanoparticles; (a3) optionally a coupling agent (a4) optionally a metal alkoxide of general formula (II) M(OR 3 ) X in which R 3 represents a C1-C4 alkyl group, M represents a metal selected from the group consisting of transition metals, lanthanides, phosphorus, magnesium, tin, zinc, aluminum and antimony and x is an integer representing the valence of the metal; (a5) optionally metal nanoparticles; b- mixing of the composition in the presence of an aqueous medium, in particular water or a water / alcohol mixture, more particularly acidified water, with stirring for the time necessary to hydrolyze and condense the organic-inorganic hybrid network, c- optional heat treatment of the composition.
2. Method according to claim 1, characterized in that the polymer is chosen from polyimides and cellulose polymers, in particular from linear polyimides and hydroxypropyl cellulose.
3. A method according to any one of claims 1 or 2, characterized in that the content of metallic or silicon-based compound (a2), in particular inorganic nanoparticles, is less than or equal to 50% by mass relative to the total mass of the composition, advantageously between 2% and 15% by mass relative to the total mass of the composition.
4. A polymer-inorganic hybrid composition obtainable by the process according to any one of claims 1 to 3.
5. Method for coating a composite substrate characterized in that it comprises the following successive steps: A- deposition of at least one layer of the hybrid composition according to claim 4 on a composite substrate; B- deposition of at least one subsequent coating layer on the composite substrate coated with the layer obtained in step A).
6. Method according to claim 5, characterized in that the thickness of the polymer-inorganic hybrid layer obtained in step A) is between 5 μm and 1 mm.
7. Method according to any one of claims 5 or 6, characterized in that the subsequent coating layer of step B) is a layer of metal, ceramic, cermet, metal oxides or reinforced or unreinforced polymer or a mixture, advantageously it is a layer of metal and / or ceramic.
8. Method according to any one of claims 5 to 7, characterized in that step B) is a thermal projection step, advantageously cold projection or plasma projection.
9. Method according to any one of claims 5 to 8, characterized in that the substrate is made of an organic matrix composite.
10. Method according to any one of claims 5 to 9, characterized in that it comprises a preliminary step alpha) of preparing the surface of the composite substrate before step A) of depositing the layer of hybrid composition, advantageously by degreasing followed by sanding or sanding.
11. A method according to any one of claims 5 to 11, characterized in that the method comprises: 10, characterized in that it comprises an intermediate step A1), between steps A) and B), of heat treatment of the coated composite substrate obtained in step A), at a maximum temperature of 150°C, advantageously for 6 hours, step B) being carried out on the substrate obtained in step A1).
12. A method according to any one of claims 5 to 10, characterized in that the method comprises: 11, characterized in that it comprises an intermediate step A2), between steps A) and B) or between the optional step A1) and step B), of increasing the surface roughness of the coated composite substrate obtained in step A) or in step A1), step B) being carried out on the substrate obtained in step A2).
13. A method according to any one of claims 5 to 10, characterized in that the method comprises: 12, characterized in that the particles deposited during step B) penetrate into the layer of the hybrid composition, thus creating a concentration gradient of particles embedded in said layer.
14. A method according to any one of claims 5 to 10, characterized in that the method comprises: 13, characterized in that the composite substrate is an engine or nacelle part, advantageously a fan blade, a fan casing or a guide vane.
15. A coated composite substrate obtainable by the method according to any one of claims 5 to 14.
16. Use of a hybrid composition according to claim 4 as an undercoat of a composite substrate in order to protect said substrate and / or to improve adhesion to said substrate, when depositing a subsequent layer.