Prepreg for ceramic matrix composites

Abstract

A prepreg, the prepreg comprising a support having more than 90% by mass of ceramic fibers, and a thermoreversible liquefiable gel at least partially coating at least a portion of the ceramic fibers, the liquefiable gel becoming liquid, for example, upon heating; 20% to 60% ceramic particles by volume relative to the volume of the liquefiable gel; 0% to 10% metal particles as a volume percentage relative to the volume of the liquefiable gel; a thermoreversible hydrocolloid in a mass percentage of 0.2% to 10% relative to the total mass of the ceramic particles and the metal particles; 0% to 7% by mass of one or more other components, preferably organic components, relative to the total mass of the ceramic particles and the metal particles; Remainder of water up to 100% Including, The prepreg, wherein the ceramic particles and the metal particles can be partially or wholly replaced by a precursor of the ceramic particles and a precursor of the metal particles, respectively, which can be formed into the ceramic particles and the metal particles, respectively, by heat treatment at a temperature above 200°C.

Description

[Technical Field]

[0001] The present invention relates to prepregs, more particularly to prepregs intended for the manufacture of ceramic matrix components, more particularly to ceramic matrix composites, i.e., CMCs. The present invention also relates to methods for manufacturing such prepregs, and to methods for manufacturing ceramic matrix components, more particularly to CMCs, from such prepregs. [Background technology]

[0002] The ceramic matrix component is essentially a product composed of ceramic fibers bonded together by a ceramic matrix. When sintered, the ceramic matrix component is known as "CMC." CMC exhibits high mechanical properties, even at high temperatures.

[0003] The ceramic matrix components can be manufactured by superimposing prepregs, each consisting of a fabric impregnated with a slurry of ceramic particles. The prepregs are flexible so that they can be molded into desired shapes. The prepregs can then be dried and preferably sintered to form a CMC.

[0004] However, ceramic matrix components, particularly CMC, manufactured from prepregs that have been stored for extended periods or under adverse conditions, exhibit degraded mechanical properties.

[0005] Therefore, there is a constant need for prepregs that exhibit better shelf life. [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] The present invention aims to satisfy this need at least partially. [Means for solving the problem]

[0007] According to the present invention, this objective is achieved by a prepreg comprising a support comprising more than 90%, more than 95%, preferably 100% of its mass being ceramic fibers, and a thermoreversible liquefiable gel that at least partially coats at least a portion of the ceramic fibers, wherein the liquefiable gel is As a volume percentage relative to the volume of the liquefiable gel, ceramic particles make up 20% to 60%. As a volume percentage relative to the volume of the liquefiable gel, 0% to 10% of metal particles, A thermoreversible hydrophilic colloid, as a mass percentage of the total mass of the ceramic particles and the metal particles, is present in an amount of 0.2% to 10%. One or more other components, preferably organic components, in mass percentage of 0% to 7% of the total mass of the ceramic particles and the metal particles. Remaining water up to 100% Includes, The ceramic particles and metal particles can be partially or completely replaced by a precursor in the form of particles, or otherwise by heat treatment at a temperature preferably above 200°C, preferably above 300°C, and preferably above 400°C, respectively.

[0008] As can be seen in more detail from the following parts of the detailed description of the present invention, the inventors have found that such prepregs retain their properties, in particular their deformability and bonding properties, even after long-term storage.

[0009] Although not bound by this theory, the inventors believe that the liquefiable gel restricts the flow between and / or on the ceramic fibers of the support, and thus restricts the movement of the ceramic particles and the metal particles. In addition, water remains at least partially trapped within the gel, thereby restricting evaporation and allowing a substantially constant composition to be maintained over time. Therefore, the prepreg advantageously remains homogeneous.

[0010] Furthermore, the composition of the liquefiable gel allows the gel to become liquid again by simple heating, and thus allows it to be deformable again easily. However, the inventors have discovered that the specificity of this composition is not harmful to the quality of the resulting ceramic matrix component, particularly the CMC.

[0011] This conversion of the liquefiable gel is thermoreversible, and the resulting liquid is a liquid that can be easily gellable by cooling.

[0012] Therefore, the prepreg is still well - suited for the production of ceramic matrix components, particularly CMC.

[0013] Finally, the water retention limits or even eliminates the need to add water during the production of the ceramic matrix component. The method of producing the ceramic matrix component is advantageously simplified as a result.

[0014] The prepreg according to the present invention may also include one or more of the following optional, preferred features: The liquefiable gel is an amount of ceramic particles greater than 25% and less than 55% as a volume percentage of the volume of the liquefiable gel, and / or an amount of metal particles greater than 0.5% and less than 9% as a volume percentage of the volume of the liquefiable gel, and / or As a mass percentage with respect to the total mass of the ceramic particles and the metal particles, an amount of a thermally reversible hydrophilic colloid that is more than 0.4% and less than 7%, and / or As a mass percentage with respect to the total mass of the ceramic particles and the metal particles, an amount of one or more other components, preferably organic components, that is more than 0.5% and less than 6% is included, The thermally reversible hydrophilic colloid is an amount that is more than 0.5% and less than 4% as a mass percentage with respect to the total mass of the ceramic particles and the metal particles, and / or the one or more other components are organic, and are selected from a dispersant, a binder, a biocide, an antifoaming agent, a thickener, a plasticizer, a drying regulator, and mixtures thereof, The ceramic particles of the liquefiable gel are selected from particles in which more than 90% of its mass consists of one or more oxides, particles in which more than 90% of its mass consists of one or more nitrides, particles in which more than 90% of its mass consists of one or more carbides, particles in which more than 90% of its mass consists of one or more borides, and mixtures of these particles, The thermally reversible hydrophilic colloid of the liquefiable gel is gelatin; agar; a mixture of carrageenan and a compound providing sodium cations and / or potassium cations and / or calcium cations; a mixture of fusellaria and sugar; a mixture of konjac gum and xanthan gum, preferably a mixture of konjac gum and xanthan gum with a mass ratio more than 0.8 and less than 1.2; a mixture of locust bean gum and xanthan gum, preferably a mixture of locust bean gum and xanthan gum with a mass ratio more than 0.67 and less than 1.5; and a mixture of chitosan and pectin, preferably a mixture of chitosan and pectin in which the mass ratio of the amount of pectin to the amount of chitosan is more than 0.2 and less than 0.8, and is selected from these, More than 90% by volume of the ceramic particles of the liquefiable gel consists of one or more oxides in which more than 90% of its mass consists, The thermoreversible hydrophilic colloid of the liquefiable gel is selected from gelatin; a mixture of chitosan and pectin, preferably a mixture of chitosan and pectin in which the mass ratio of the amount of pectin to the amount of chitosan is greater than 0.2 and less than 0.8, and is preferably gelatin. In the liquefiable gel, the ratio of the mass of the "other components" to the mass of the thermoreversible hydrophilic colloid is less than 1, preferably less than 0.9, preferably less than 0.8, preferably less than 0.6, and preferably less than 0.4, and the amount of the thermoreversible hydrophilic colloid and the amount of the "other components" are expressed as mass percentages relative to the total mass of the ceramic particles and the metal particles. In the liquefiable gel, the ratio of the mass amount of the plasticizer, preferably a polyol, to the mass of the thermoreversible hydrophilic colloid is less than 1, preferably less than 0.9, preferably less than 0.8, preferably less than 0.6, and preferably less than 0.4, and the amount of thermoreversible hydrophilic colloid and the amount of plasticizer are expressed as mass percentages relative to the total mass of the ceramic particles and the metal particles. In the liquefiable gel, the water content by volume is more than 40%, preferably more than 50%, and / or preferably less than 70%, preferably less than 60%. In the liquefiable gel, the total content of the thermoreversible hydrophilic colloid and the organic "other components," preferably the total content of the thermoreversible hydrophilic colloid and the "other components," is less than 15%, preferably less than 10%, preferably less than 7%, and preferably less than 5%, as a mass percentage of the total mass of the ceramic particles and metal particles in the liquefiable gel. Chemical analysis shows that more than 95% by volume of the ceramic particles consists of more than 99% of its mass of one or more oxides, and that the mass percentage based on these oxides is Al2O3+SiO2≧95%. The support, which may be optionally assembled in the form of a yarn, has more than 90% by number of ceramic fibers with a length greater than 10 mm and an equivalent diameter greater than 2 μm and less than 50 μm, measured at half the total length. The ceramic fiber of the support consists of more than 90% by mass of one or more oxides and / or one or more nitrides and / or one or more carbides and / or one or more borides and / or carbon. The support is a single yarn, a yarn web, a yarn braid, a yarn knit, or a fiber entanglement, wherein more than 50% of the yarn, or more than 50% of the number of the yarns or ceramic fibers, has more than 50% of its outer surface coated with a liquefiable gel. The ceramic fibers of the support, which may be optionally assembled in the form of yarn, consist of more than 95% of their mass of one or more oxides, and chemical analysis shows that Al2O3+SiO2≧95% is the mass percentage based on the oxides. The ceramic fibers of the support, which may optionally be assembled in the form of yarn, are selected from glass fibers, amorphous silica fibers, corundum fibers, mullite fibers, mullite-corundum fibers, and mixtures thereof. The support consists of multiple superimposed webs, preferably more than two webs and less than ten webs. In the liquefiable gel, The ceramic particles constitute more than 25% and less than 55% of the volume of the liquefiable gel, wherein the ceramic particles are selected from particles in which more than 90% of the mass consists of one or more oxides, particles in which more than 90% of the mass consists of one or more nitrides, particles in which more than 90% of the mass consists of one or more carbides, particles in which more than 90% of the mass consists of one or more borides, and mixtures thereof, and the total median diameter D of the ceramic particles is less than 5 μm and greater than 0.1 μm by volume. 50 , and the 99th percentile of less than 50 μm, i.e., D 99 Show, The thermoreversible hydrophilic colloid is present in an amount greater than 0.4% and less than 9% as a mass percentage based on the mass of the ceramic particles, where the thermoreversible hydrophilic colloid is selected from gelatin; agar; a mixture of carrageenan and a compound providing sodium cations and / or potassium cations and / or calcium cations; a mixture of furcellaria and sugar; a mixture of konjac gum and xanthan gum in a mass ratio greater than 0.8 and less than 1.2; a mixture of locust bean gum and xanthan gum in a mass ratio greater than 0.67 and less than 1.5; and a mixture of chitosan and pectin in which the mass ratio of pectin to the amount of chitosan is greater than 0.2 and less than 0.8, wherein the thermoreversible hydrophilic colloid is preferably gelatin. The other components are organic and present in an amount greater than 0.1% and less than 6% by mass based on the mass of the ceramic particles, wherein the other components are selected from dispersants, binders, biocides, defoamers, thickeners, plasticizers, drying regulators and mixtures thereof. In the support, The support, which may be optionally assembled in the form of a yarn, has more than 90% by number of ceramic fibers with a length greater than 10 mm and an equivalent diameter greater than 2 μm and less than 50 μm, measured at half the total length. The ceramic fibers, which may be optionally assembled in the form of yarn, constitute more than 90% of the mass of the support, and more than 90% of the mass of the ceramic fibers, which may be optionally assembled in the form of yarn, consists of one or more oxides and / or one or more nitrides and / or one or more carbides and / or one or more borides and / or carbon. The support is a single yarn, a yarn web, a yarn braid, a yarn knit, or an entanglement of fibers, wherein more than 50% of the single yarn, or more than 50% of the number of yarns or fibers, has more than 50% of its outer surface coated with a liquefiable gel. In the liquefiable gel, The ceramic particles constitute more than 25% and less than 55% of the volume of the liquefiable gel, wherein the ceramic particles are selected from particles in which more than 90% of the mass consists of one or more oxides, particles in which more than 90% of the mass consists of one or more nitrides, particles in which more than 90% of the mass consists of one or more carbides, particles in which more than 90% of the mass consists of one or more borides, and mixtures thereof. The amount of the metal particles is greater than 0.5% and less than 9% of the volume of the liquefiable gel. The ceramic particles and metal particles as a whole have a median diameter D of less than 5 μm and greater than 0.1 μm by volume. 50 , and the 99th percentile of less than 50 μm, i.e., D 99 Show, The thermoreversible hydrophilic colloid is present in an amount greater than 0.4% and less than 9% as a mass percentage based on the sum of the mass of the ceramic particles and the mass of the metal particles, selected from gelatin, agar, a mixture of carrageenan and a compound providing sodium cations and / or potassium cations and / or calcium cations, a mixture of furcellaria and sugar, a mixture of konjac gum and xanthan gum in a mass ratio greater than 0.8 and less than 1.2, a mixture of locust bean gum and xanthan gum in a mass ratio greater than 0.67 and less than 1.5, and a mixture of chitosan and pectin in which the mass ratio of pectin to the amount of chitosan is greater than 0.2 and less than 0.8, wherein the thermoreversible hydrophilic colloid is preferably gelatin. The other components are organic and present in an amount greater than 0.1% and less than 6% as a mass percentage based on the sum of the mass of the ceramic particles and the mass of the metal particles, wherein the other components are selected from dispersants, binders, biocides, defoamers, thickeners, plasticizers, drying regulators and mixtures thereof. In the support, The support, which may be optionally assembled in the form of a yarn, has more than 90% by number of ceramic fibers with a length greater than 10 mm and an equivalent diameter greater than 2 μm and less than 50 μm, measured at half the total length. The ceramic fibers, which may be optionally assembled in the form of yarn, constitute more than 90% of the mass of the support, and more than 90% of the mass of the ceramic fibers, which may be optionally assembled in the form of yarn, consists of one or more oxides and / or one or more nitrides and / or one or more carbides and / or one or more borides and / or carbon. The support is a single yarn, a yarn web, a yarn braid, a yarn knit, or an entanglement of fibers, wherein more than 50% of the single yarn, or more than 50% of the number of yarns or fibers, has more than 50% of its outer surface coated with a liquefiable gel. In the liquefiable gel, The amount of the ceramic particles is greater than 30% and less than 50% of the volume of the liquefiable gel. Chemical analysis shows that more than 95% by volume of the ceramic particles consists of more than 99% of its mass of one or more oxides, and that the mass percentage based on these oxides is Al2O3+SiO2≧95%. The overall size of the ceramic particles is less than 5 μm and greater than 0.1 μm in median diameter D. 50 , and the 99th percentile of less than 50 μm, i.e., D 99 Show, The thermoreversible hydrophilic colloid is present in an amount greater than 0.5% and less than 4% of the mass of the ceramic particles, where the thermoreversible hydrophilic colloid is gelatin. The other components are organic and present in an amount greater than 0.1% and less than 6% by mass based on the mass of the ceramic particles, wherein the other organic components are selected from dispersants, binders, biocides, defoamers, thickeners, plasticizers, drying regulators and mixtures thereof. In the support, The support, which may be optionally assembled in the form of a yarn, has more than 90% by number of ceramic fibers with a length greater than 10 mm and an equivalent diameter greater than 2 μm and less than 30 μm, measured at half the total length. The ceramic fibers, which may be optionally assembled in the form of yarn, constitute more than 90% of the mass of the support. The fiber, which may be optionally assembled into a yarn form, consists of more than 95% of its mass of one or more oxides, and chemical analysis shows that Al2O3+SiO2≧95% is the mass percentage based on the oxides. The support is a single yarn, a yarn web, a yarn braid, a yarn knit, or an entanglement of fibers, wherein more than 50% of the yarn, or more than 50% of the number of yarns or fibers, are coated with a liquefiable gel on more than 50% of their outer surface.

[0015] The present invention also relates to a method for producing a prepreg intended for the production of a ceramic matrix component, particularly a CMC, and especially a prepreg according to the present invention, 1) Prepare a gellable liquid having the following composition: As a volume percentage relative to the volume of the gelable liquid, ceramic particles make up 20% to 60%. As a volume percentage relative to the volume of the gelatable liquid, 0% to 10% of metal particles, A thermoreversible hydrophilic colloid, as a mass percentage of the total mass of the ceramic particles and the metal particles, is present in an amount of 0.2% to 10%. One or more other components, preferably organic components, in mass percentage of 0% to 7% of the total mass of the ceramic particles and the metal particles. Remaining water up to 100%, 2) Applying the gellable liquid to the ceramic fibers of the fibrous support, 3) By lowering the temperature of the gellable liquid, the gellable liquid is gelled into a liquefiable gel form to obtain the prepreg. 4) Preferably, the prepreg is stored. The above method includes the following steps.

[0016] Preferably, the thermoreversible hydrophilic colloid is selected such that the gelling temperature of the gelling liquid is greater than 20°C and less than 60°C.

[0017] The present invention relates to a method for producing ceramic matrix components, particularly ceramic matrix composites, 5) To convert the liquefiable gel into a gellable liquid, liquefy the liquefiable gel of the prepreg, which has been manufactured according to the present invention or according to steps 1) to 3), preferably 4), 6) Molding the prepreg to obtain a deformable preform, 7) Optionally, the gellable liquid is gelled to obtain a cured preform. 8) Dry the preform obtained from step 6) or optionally from step 7) to obtain a ceramic matrix component. 9) Optionally, sinter the ceramic matrix component obtained from step 8). The above method includes the following steps.

[0018] A method for producing a ceramic matrix component according to the present invention includes steps 1) to 3) of a method for producing a prepreg according to the present invention, prior to step 5), and in one embodiment, includes step 4) of storing the prepreg for a period of more than one week, more than one month, more than two months, more than six months, and more than twelve months.

[0019] The present invention also relates to an intermediate product obtained from step 5), and a preform obtained from step 6) or 7).

[0020] definition In accordance with the present invention, the term “prepreg” is understood to mean a support consisting essentially of ceramic fibers, at least partially impregnated with a thermoreversible liquefiable gel or a thermoreversible gelling liquid, wherein the thermoreversible liquefiable gel and the thermoreversible gelling liquid include ceramic particles and / or precursors of ceramic particles, and optionally metal particles and / or precursors of metal particles.

[0021] The support may take the form of, for example, yarn, web, fabric, felt blocks, braids, knitted fabrics, or assemblies of these elements. The ceramic matrix component, in particular the CMC, may be manufactured using a single prepreg or a superposition of two or more prepregs.

[0022] The term "ceramic" is understood to mean a material that is neither metallic nor organic. In the context of this invention, carbon, glass, and amorphous silica are considered ceramic materials.

[0023] The term “thermally reversible hydrophilic colloid” is understood to mean the whole of (dry) components that, after the addition of a certain amount of water, are involved in the formation of a thermoreversible liquefiable gel; that is, without the addition of water, do not result in the formation of a thermoreversible liquefiable gel. Gelatin or a mixture of locust bean gum and xanthan gum are examples of thermoreversible hydrophilic colloids. Thermoreversible hydrophilic colloids include hydrophilic colloids. However, not all hydrophilic colloids in a thermoreversible hydrophilic colloid are “thermally reversible hydrophilic colloids” themselves. For example, locust bean gum and xanthan gum are not thermoreversible when used in isolation. What should be evaluated is the thermoreversibility of the liquefiable gel. For example, gelatin is a thermoreversible hydrophilic colloid only insofar as it, together with the other components of the liquefiable gel, results in a thermoreversible liquefiable gel.

[0024] The “other components” are components other than the ceramic particles, the precursors of the ceramic particles, the metal particles, the precursors of the metal particles, the thermoreversible hydrophilic colloid, and water.

[0025] The content of thermoreversible hydrophilic colloids and the content of "other components" are always expressed as a mass percentage relative to the total mass of the ceramic particles and the metal particles.

[0026] The term "gelation temperature" for a thermoreversible hydrophilic colloidal sol or gelatable liquid refers to the starting temperature at which the sol or gelatable liquid begins to gel when its temperature is reduced.

[0027] In the context of liquefiable gels, the term "liquefaction temperature" refers to the starting temperature at which the liquefiable gel begins to liquefy when its temperature is increased.

[0028] A "fiber" is a filament whose length is greater than five times its equivalent diameter.

[0029] The "equivalent diameter" of a fiber is the diameter of a disk having the same surface area as its cross-section at half its total length.

[0030] A "yarn" is an assembly of fibers containing more than 10, and preferably less than 500,000, fibers in cross-section, with a length greater than 5 times its diameter.

[0031] A "long fiber" is a fiber whose length is greater than 1 mm. A "long yarn" is a yarn made up of multiple long fibers.

[0032] A "continuous fiber" is a fiber whose length is greater than 10 mm. A "continuous yarn" is a yarn (or "staple yarn") whose length is greater than 10 mm and which consists of continuous fibers or aligned assemblies of short and / or long fibers.

[0033] In the context of this specification, “sintering” means strengthening of a preform by heat treatment at a temperature above 700°C, which may involve partial or complete melting of some (but not all) of the components of the preform.

[0034] 50(D 50 (as shown) and 99(D 99The "percentile", as shown, refers to the particle sizes corresponding to percentages equal to 50% and 99% by volume, respectively, with respect to the cumulative particle size distribution curve of a set of particles, and the particle sizes are classified in ascending order. Therefore, according to this definition, 99% by volume of the set of particles has a size less than D 99 and 1% by volume of the particles has a size greater than D 99 In the case of a powder, the percentile can be determined by the particle size distribution generated using a Camsizer (trademark) XT sold by Horiba.

[0035] The "median diameter" of a set of particles refers to the 50th percentile. Therefore, the median diameter divides the particles of the set into a first population and a second population of equal volume, and these first and second populations contain only particles showing a size greater than or less than the median diameter, respectively.

[0036] The particles can be individual elements of a powder, or by extension, individual elements in a gellable liquid or a liquefiable gel.

[0037] Unless otherwise stated, all oxide contents are mass percentages based on the oxide. The content by mass of the oxide of a metallic element refers to the total content of this element expressed in the most stable oxide form according to standard industrial agreements.

[0038] The sum of the oxide contents does not necessarily imply the presence of all these oxides. For example, "Al2O3 + SiO2" is the sum of the content of Al2O3 and the content of SiO2, but does not exclude the absence of one of these oxides.

[0039] "Include" or "comprise" or "have" / "exhibit" should be interpreted as non - limiting.

[0040] Unless otherwise stated, all averages are arithmetic averages. [Modes for carrying out the invention]

[0041] Method for manufacturing prepregs A method for producing a prepreg according to the present invention comprises the steps 1) to 3) described above, preferably step 4).

[0042] In step 1), the gellable liquid is prepared.

[0043] The gellable liquid can be produced by mixing the thermoreversible hydrophilic colloid, the ceramic particles, and optionally the metal particles and one or more other components, preferably one or more organic components, in water. Any conventional mixing technique may be used.

[0044] The ceramic particles are intended to form a binding matrix for the ceramic matrix components, particularly the CMC.

[0045] Preferably, the amount of ceramic particles is more than 25%, preferably more than 30%, and / or less than 55%, preferably less than 50%, as a volume percentage of the volume of the gellable liquid.

[0046] Preferably, the ceramic particles are selected from particles in which more than 90%, preferably more than 95%, preferably more than 99%, preferably substantially 100% by mass consists of one or more oxides, particles in which more than 90%, preferably more than 95%, preferably more than 99%, preferably substantially 100% by mass consists of one or more nitrides, particles in which more than 90%, preferably more than 95%, preferably more than 99%, preferably substantially 100% by mass consists of one or more carbides, particles in which more than 90%, preferably more than 95%, preferably more than 99%, preferably substantially 100% by mass consists of one or more borides, and mixtures of these particles.

[0047] Preferably, if the ceramic particles contain an oxide, the ceramic particles contain an oxide selected from Al2O3, SiO2, ZrO2, Y2O3, CaO, MgO, SrO, BaO, K2O, rare earth oxides, TiO2, Na2O, Cr2O3, and mixtures thereof.

[0048] Preferably, if the ceramic particles contain nitrides, the ceramic particles contain nitrides selected from AlN, BN, Si3N4 and mixtures thereof.

[0049] Preferably, if the ceramic particles contain carbides, the ceramic particles contain carbides selected from SiC, B4C, TiC, TaC, ZrC, and mixtures thereof.

[0050] Preferably, if the ceramic particles contain boride, the ceramic particles contain ZrB2.

[0051] More preferably, more than 90% by volume of the ceramic particles, preferably more than 95% by volume, preferably more than 99% by volume, preferably substantially 100% by volume, consists of one or more oxides, with more than 90% by mass, preferably more than 95% by volume, preferably more than 99% by volume, preferably substantially 100%.

[0052] Preferably, more than 90% by volume of the ceramic particles, preferably more than 95% by volume, preferably more than 99% by volume, preferably substantially 100% by volume, consists of one or more oxides, where the chemical analysis shows, as a mass percentage based on the oxides, Al2O3+SiO2+ZrO2+Y2O3+CaO+MgO+SrO+BaO+K2O+the rare earth oxide+TiO2+Na2O+Cr2O3≧90%, preferably ≧95%, preferably ≧99%. Preferably, this sum of oxide content is substantially equal to 100% as a mass percentage based on the oxides.

[0053] More preferably, more than 90% by volume of the ceramic particles, preferably more than 95% by volume, preferably more than 99% by volume, preferably substantially 100% by volume, consists of one or more oxides, and chemical analysis shows that Al2O3+SiO2 ≥ 90%, preferably ≥ 95%, preferably ≥ 99% by mass, based on the oxides. Preferably, this sum of oxide content is substantially equal to 100% by mass, based on the oxides.

[0054] In one embodiment, a chemical analysis shows that more than 90% by volume of the ceramic particles, preferably more than 95% by volume, preferably more than 99% by volume, preferably substantially 100% by volume, consists of one or more oxides, where the mass percentage based on the oxides is SiO2 ≥ 90%, preferably ≥ 95%, preferably ≥ 99%.

[0055] In one embodiment, a chemical analysis shows that more than 90% by volume of the ceramic particles, preferably more than 95% by volume, preferably more than 99% by volume, preferably substantially 100% by volume, consists of one or more oxides, where Al2O3 ≥ 90%, preferably ≥ 95%, preferably ≥ 99% by mass, based on the oxides.

[0056] The ceramic particles may be partially or completely replaced by precursors of the ceramic particles, that is, by components that result in ceramic particles or ceramic matrix, respectively, during the manufacture of the prepreg, or more generally, during the manufacture or use of the ceramic matrix component, particularly the CMC. Boehmite, alumina trihydrate, tetraethyl orthosilicate or TEOS, and orthosilicate are examples of known precursors of alumina, alumina silica, and silica, respectively.

[0057] In one embodiment, the gelatable liquid contains metal particles in an amount preferably greater than 0.5%, more preferably greater than 1%, and / or less than 9%, more preferably less than 8%, and more preferably less than 5%, as a volume percentage of the volume of the gelatable liquid.

[0058] The metal particles, i.e., particles made from metal or metal alloy, are intended to be incorporated into the ceramic matrix component, particularly the CMC. The particles can modify the properties of the matrix, such as thermal conductivity and / or electrical conductivity. If the metal particles are precursors to ceramic particles and are converted into ceramic particles, particularly during a sintering operation, preferably a reactive sintering operation, then the metal particles are exclusively counted as one of the precursors to ceramic particles.

[0059] Reactive sintering may be particularly suitable for converting metal particles into ceramic particles in combination with elements of a gaseous environment, especially nitrogen and / or oxygen.

[0060] More preferably, all or part of the metal particles consist of a material selected from silicon, aluminum, iron, and mixtures thereof, particularly alloys thereof, and are preferably made from such material.

[0061] The entirety of the metal particles may consist of particles having the same composition, or a mixture of particles having different compositions.

[0062] The metal particles may be partially or completely replaced by metal particle precursors, that is, by components that introduce a metallic phase during the manufacture of the prepreg, or more generally, during the manufacture or use of the ceramic matrix component, particularly the CMC. Examples of metal precursors include metal sulfates, such as aluminum sulfate, metal chlorohydrates, such as aluminum chlorohydrate, and metal bromohydrates, such as aluminum bromohydrate.

[0063] Preferably, the gellable liquid does not contain metal particle precursors.

[0064] In a preferred embodiment, the gellable liquid does not contain metal particles or precursors of such particles.

[0065] Preferably, the total size of the ceramic particles and metal particles has a median diameter D of less than 10 μm by volume, preferably less than 8 μm, preferably less than 6 μm, preferably less than 5 μm, preferably less than 4 μm, preferably less than 3 μm, and preferably greater than 0.1 μm, preferably greater than 0.2 μm. 50 , and / or the 99th percentile of less than 70 μm, preferably less than 60 μm, preferably less than 50 μm, preferably less than 40 μm, preferably less than 30 μm, i.e., D 99 The ceramic particles and metal particles in the gelable liquid may have a unimodal size distribution, but may also have a multimodal size distribution.

[0066] The ceramic particles and metal particles as a whole may preferably have a bimodal distribution in which the "first peak" is centered at a size of 0.1 to 0.3 μm and the "second peak" is centered at a size of 0.5 μm to 5 μm. Preferably, the two peaks do not overlap at all, even partially. More preferably, the group of particles having a distribution centered at the first peak corresponds to less than 50 volume percent of the total ceramic particles and metal particles.

[0067] The thermoreversible hydrophilic colloid is intended to enable reversible gelation under the effect of decreasing temperature, and therefore to allow for a significant modification of the viscosity of the gellable liquid. Therefore, the hydrophilic colloid is also suitable for enabling the resulting gel to be reversibly liquefied under the effect of increasing temperature.

[0068] Hydrophilic colloids suitable for imparting reversible gelling and liquefaction capabilities under the effects of temperature decrease and temperature increase are well known.

[0069] Glycols, vinyl alcohol, or acacia gum are not thermoreversible hydrophilic colloids.

[0070] Certain cellulose gums, such as methylcellulose, exhibit thermoreversible behavior. These gums impart the properties of gelling under increasing temperature and liquefying under decreasing temperature, which is the reverse of the behavior of the thermoreversible hydrophilic colloid used according to the present invention.

[0071] The amount of thermoreversible hydrophilic colloid is preferably more than 0.4%, preferably more than 0.5%, preferably more than 0.7%, and / or preferably less than 9%, preferably less than 7%, preferably less than 5%, preferably less than 4%, and preferably less than 3%, as a mass percentage based on the sum of the mass of the ceramic particles and the mass of the metal particles.

[0072] Preferably, the thermoreversible hydrophilic colloid is selected such that the gelling temperature of the gelling liquid is greater than 20°C, preferably greater than 25°C, preferably greater than 30°C, and preferably less than 60°C, preferably less than 50°C, preferably less than 45°C, and preferably less than 40°C.

[0073] The thermoreversible hydrophilic colloid is preferably, Gelatin, or Agar, or A mixture of carrageenan and a compound that provides sodium cations and / or potassium cations and / or calcium cations, or A mixture of Furcellaria and sugar, or Preferably a mixture of konjac gum and xanthan gum in a mass ratio greater than 0.8 and less than 1.2, or Preferably a mixture of locust bean gum and xanthan gum in a mass ratio greater than 0.67 and less than 1.5, or A mixture of chitosan and pectin in which the mass ratio of the amount of pectin to the amount of chitosan is preferably greater than 0.2 and less than 0.8, preferably less than 0.5. That is the case.

[0074] Preferably, the thermoreversible hydrophilic colloid is selected from gelatin and a mixture of chitosan and pectin in which the mass ratio of pectin to chitosan is preferably greater than 0.2 and less than 0.8, preferably less than 0.5. Preferably, the thermoreversible hydrophilic colloid is gelatin.

[0075] The dissolution of the thermoreversible hydrophilic colloid in water can be carried out by any technique known to those skilled in the art, particularly by mixing, preferably by gentle mechanical mixing.

[0076] The “other components” do not contribute to the gelatable properties of the gelatable liquid, i.e., its ability to gel. In other words, the other components are not components of the thermoreversible hydrophilic colloid. For example, if the thermoreversible hydrophilic colloid is a mixture of locust bean gum and xanthan gum, neither the locust bean gum nor the xanthan gum is considered an “other component.” Similarly, for example, if the thermoreversible hydrophilic colloid is a mixture of chitosan and pectin, neither the chitosan nor the pectin is considered an “other component.”

[0077] If the thermoreversible hydrophilic colloid contains chitosan, the pH of the gellable liquid is preferably lower than the reciprocal of the base-10 logarithm of the acid dissociation constant, i.e., pKa, of the chitosan in water.

[0078] Preferably, the "one or more other components" are organic.

[0079] The amount of one or more other components is preferably more than 0.1%, preferably more than 0.5%, and / or preferably less than 6%, and preferably less than 5%, as a mass percentage based on the sum of the mass of the ceramic particles and the mass of the metal particles.

[0080] The amount of the other components should be limited so that they do not significantly affect the behavior of the liquefyable gel. The other components may have an effect on the liquefaction temperature of the liquefyable gel, in particular as a function of the amount of the thermoreversible hydrophilic colloid of the liquefyable gel, but may also have an effect on the mechanical properties of the ceramic matrix components, in particular the coefficient of fracture.

[0081] Preferably, in the gellable liquid, the ratio of the mass of the "other components" to the mass of the thermoreversible hydrophilic colloid is less than 1, preferably less than 0.9, preferably less than 0.8, preferably less than 0.6, and preferably less than 0.4, and the amounts of the thermoreversible hydrophilic colloid and the "other components" are expressed as mass percentages relative to the total mass of the ceramic particles and the metal particles.

[0082] Particularly preferably, in the gellable liquid, the ratio of the mass amount of the plasticizer, preferably a polyol, of the liquefiable gel to the mass of the thermoreversible hydrophilic colloid is less than 1, preferably less than 0.9, preferably less than 0.8, preferably less than 0.6, and preferably less than 0.4, where the amount of thermoreversible hydrophilic colloid and the amount of plasticizer are expressed as mass percentages of the total mass of the ceramic particles and the metal particles. Advantageously, the mechanical properties of the ceramic matrix component, particularly the fracture coefficient, are improved.

[0083] The presence of organic components often necessitates special measures, particularly to extract vapors released by the organic components, limit the risk of ignition and / or explosion, avoid the dispersion of the organic components during transport, and stabilize the storage of the organic components. Therefore, a reduced content of other components, preferably organic components, is particularly advantageous as it facilitates the removal of the organic components, especially during debinding.

[0084] Preferably, in the gelatable liquid, the total content of the thermoreversible hydrophilic colloid and the organic "other components," preferably the total content of the thermoreversible hydrophilic colloid and the "other components," is less than 15%, preferably less than 10%, preferably less than 7%, and preferably less than 5%, as a mass percentage of the total mass of the ceramic particles and the metal particles in the gelatable liquid.

[0085] Preferably, the "one or more other components" are selected from dispersants, binders, biocides, defoamers, thickeners, plasticizers, drying regulators, and mixtures thereof.

[0086] Preferably, the gelling liquid contains a binder, preferably selected from polyethylene glycol, polyvinyl alcohol, and mixtures thereof, in an amount of more than 0.5%, preferably more than 1% and / or less than 3%, and preferably less than 2.5%, as a mass percentage based on the sum of the mass of the ceramic particles and the mass of the metal particles.

[0087] Preferably, the gelling liquid contains a biocide in an amount of more than 0.1% and / or less than 1%, preferably less than 0.5%, as a mass percentage based on the sum of the masses of the ceramic particles and the metal particles. PREVENTOL® P301, marketed by Lanxess, is an example of a known biocide.

[0088] The gelling liquid may contain, as a mass percentage based on the sum of the masses of the ceramic particles and the metal particles, preferably more than 0.1%, preferably more than 0.2% and / or less than 1%, preferably less than 0.5%, a dispersant selected from preferably ammonium polyacrylate, sodium polyacrylate, modified polycarboxylate ether, sodium salt of a condensation product of naphthalene sulfonic acid, ammonium polymethacrylate solution, and mixtures thereof. The Darvan® product line sold by Vanderbilt Minerals is a well-known example of a dispersant.

[0089] The gellable liquid may contain an amount of antifoaming agent preferably greater than 0.01%, preferably greater than 0.02%, and / or less than 1%, preferably less than 0.5%, as a mass percentage based on the sum of the masses of the ceramic particles and the metal particles. The CONTRASPUM group of antifoaming agents sold by Zschimmer & Schwarz are well known.

[0090] The gelling liquid may contain a thickening agent in an amount of preferably more than 0.1%, preferably more than 0.2%, and / or less than 2%, preferably less than 1%, as a mass percentage based on the sum of the mass of the ceramic particles and the mass of the metal particles. ACRONAL® S790, sold by BASF, is a well-known thickening agent.

[0091] The gellable liquid may contain a plasticizer for the liquefyable gel, preferably a polyol, in an amount of more than 0.01%, preferably more than 0.02%, and / or less than 5%, preferably less than 4%, as a mass percentage based on the sum of the mass of the ceramic particles and the mass of the metal particles.

[0092] The gellable liquid may contain a drying modifier in an amount of preferably more than 0.1% and / or less than 2% by mass, based on the combined mass of the ceramic particles and the metal particles. Cyclohexane, dimethyl phthalate, diphenyl phthalate, diethyl phthalate, and triethanolamine are well known drying modifiers.

[0093] In one embodiment, particularly when a precursor of ceramic particles in colloidal form is used, the pH of the gellable liquid can be adjusted, for example, by adding a base or acid to improve gelation.

[0094] When a precursor of ceramic particles in colloidal form is used, preferably, water is added together with the thermoreversible hydrophilic colloid, and then the other components of the gellable liquid are added.

[0095] In the gellable liquid, the volumetric water content is preferably more than 40%, preferably more than 50%, and / or preferably less than 70%, preferably less than 60%.

[0096] Preferably, the water is desalinated water.

[0097] In a preferred embodiment, the thermoreversible hydrophilic colloid is gelatin in an amount of preferably more than 0.5%, preferably more than 1%, preferably less than 9%, preferably less than 7%, preferably less than 5%, preferably less than 4%, preferably less than 3%, preferably less than 2.5%, and preferably less than 2%, as a mass percentage based on the sum of the mass of the ceramic particles and the mass of the metal particles, and the water into which the thermoreversible hydrophilic colloid is introduced is preferably heated to a temperature of preferably more than 60°C, preferably more than 65°C, and preferably less than 75°C, and preferably less than 70°C.

[0098] In one embodiment, the thermoreversible hydrophilic colloid is a mixture of chitosan and pectin in which the mass ratio of the amount of pectin to the amount of chitosan is preferably greater than 0.2 and less than 0.8, preferably less than 0.5, and the amount is preferably greater than 0.4%, preferably greater than 0.5%, preferably less than 9%, preferably less than 7%, preferably less than 5%, preferably less than 4%, preferably less than 3%, preferably less than 2.5%, preferably less than 2%, as a mass percentage based on the total mass of the ceramic particles and the metal particles, and the water into which the thermoreversible hydrophilic colloid is introduced is at a temperature of greater than 50°C, preferably greater than 55°C, preferably less than 65°C, preferably less than 60°C.

[0099] In a preferred embodiment, the hydrophilic colloidal solution is first prepared by dissolving the thermoreversible hydrophilic colloid in water, the hydrophilic colloidal solution being at a temperature higher than its gelation temperature. Next, the thermoreversible hydrophilic colloidal solution is mixed with the other components of the gellable liquid.

[0100] Preferably, the thermoreversible hydrophilic colloid is selected such that the gelation temperature of the thermoreversible hydrophilic colloid solution is greater than 20°C, preferably greater than 25°C, preferably greater than 30°C, and preferably less than 60°C, preferably less than 50°C, preferably less than 45°C, and preferably less than 40°C. Those skilled in the art know how to determine the gelation temperature of the hydrophilic colloid solution depending on the thermoreversible hydrophilic colloid by simple routine tests.

[0101] In step 2), the gellable liquid is applied to the ceramic fibers of the support.

[0102] Preferably, the ceramic fibers, which may be optionally assembled in the form of yarn, constitute more than 90%, more than 95%, preferably 100%, of the mass of the support.

[0103] Preferably, more than 50%, more than 70%, more than 90%, preferably 100% of the ceramic fibers, which may be optionally assembled in the form of a yarn. Lengths exceeding 10 mm, and Equivalent diameter measured at half the total length, greater than 2 μm, preferably greater than 4 μm, preferably greater than 6 μm and / or preferably less than 50 μm, preferably less than 30 μm, preferably less than 20 μm. It has.

[0104] The ceramic fiber may contain a sizing agent ("sizing") and / or the ceramic yarn may have an organic surface coating ("finish"); the sizing agent and / or the coating may be at least partially removed by chemical and / or thermal means before the application of the gellingable liquid, the sizing agent conventionally amounting to less than 1% of the mass of the ceramic fiber it at least partially covers, and the coating conventionally amounting to less than 4% of the mass of the ceramic yarn it at least partially covers.

[0105] Preferably, the ceramic fiber, which may optionally be assembled in the form of a yarn, consists of more than 90%, preferably more than 95%, preferably more than 99%, preferably substantially 100% of its mass, consisting of one or more oxides and / or one or more nitrides and / or one or more carbides and / or one or more borides and / or carbon, preferably one or more oxides and / or one or more carbides and / or carbon, preferably oxides selected from Al2O3, SiO2, ZrO2, Y2O3, CaO, MgO, iron oxides, rare earth oxides, TiO2, Na2O, Cr2O3 and mixtures thereof, or SiC.

[0106] More preferably, the ceramic fiber, which may be optionally assembled in the form of a yarn, consists of one or more oxides, with more than 90%, preferably more than 95%, preferably more than 99%, and preferably substantially 100% of its mass.

[0107] Preferably, the ceramic fiber, which may optionally be assembled in the form of a yarn, exhibits a chemical analysis such that more than 90%, preferably more than 95%, preferably more than 99%, preferably substantially 100%, of its mass consists of one or more oxides, and the weight percentage based on the oxides is Al2O3+SiO2+ZrO2+Y2O3+CaO+MgO+Fe2O3+rare earth oxides+TiO2+Na2O+Cr2O3≧90%, preferably ≧95%, preferably ≧99%, preferably substantially equal to 100%.

[0108] Preferably, the ceramic fiber, which may be optionally assembled in the form of a yarn, exhibits a chemical analysis such that more than 90%, preferably more than 95%, preferably more than 99%, preferably substantially 100%, of its mass consists of one or more oxides, and the mass percentage based on the oxides is Al2O3+SiO2≧90%, preferably ≧95%, preferably ≧99%, preferably substantially equal to 100%. Preferably, the ceramic fiber, which may be optionally assembled in the form of a yarn, is selected from glass fiber, amorphous silica fiber, corundum fiber, mullite fiber, mullite-corundum fiber, and mixtures thereof.

[0109] In one embodiment, the ceramic fiber, which may be optionally assembled in the form of a yarn, exhibits a chemical analysis in which more than 90%, preferably more than 95%, preferably more than 99%, and preferably substantially 100% of its mass consists of one or more oxides, and the mass percentage based on the oxides is SiO2 ≥ 90%, preferably ≥ 95%, and preferably ≥ 99%. Preferably, in this embodiment, the ceramic fiber, which may be optionally assembled in the form of a yarn, is selected from glass fiber, amorphous silica fiber, and mixtures thereof.

[0110] In one embodiment, the ceramic fiber, which may be optionally assembled in the form of a yarn, exhibits a chemical analysis in which more than 90%, preferably more than 95%, preferably more than 99%, and preferably substantially 100% of its mass consists of one or more oxides, and the mass percentage based on the oxides is Al2O3 ≥ 90%, preferably ≥ 95%, and preferably ≥ 99%. Preferably, in this embodiment, the ceramic fiber, which may be optionally assembled in the form of a yarn, is a corundum fiber.

[0111] In one embodiment, the ceramic fiber, which may be optionally assembled in the form of a yarn, exhibits a chemical analysis in which more than 90%, preferably more than 95%, preferably more than 99%, preferably substantially 100%, of its mass consists of one or more oxides, and the mass percentage based on the oxides is Al2O3 ≥ 50%, preferably ≥ 60%, preferably ≥ 70% and ≤ 90%. Preferably, in this embodiment, the ceramic fiber, which may be optionally assembled in the form of a yarn, is selected from mullite fiber, mullite-corundum fiber, and mixtures thereof.

[0112] In the material of the ceramic fiber, optionally in the form of yarn, the material of the ceramic particles may be the same or different.

[0113] Preferably, the ceramic fibers, which may optionally be assembled in the form of yarn, are selected from glass fibers, amorphous silica fibers, corundum fibers, mullite fibers, mullite-corundum fibers, and mixtures thereof, and the ceramic particles consist of one or more oxides by mass, more than 90%, preferably more than 95%, preferably more than 99%, preferably substantially 100%, and exhibit a chemical analysis in which Al2O3+SiO2 ≥ 90%, preferably ≥ 95%, preferably ≥ 99% as a mass percentage based on the oxides. Preferably, this sum of oxide content is substantially equal to 100% as a mass percentage based on the oxides.

[0114] The support can take the form of a web, preferably a fabric having weft and warp yarns, a knit or braid, or a single layer of felt.

[0115] The web, preferably the fabric, may have a thickness of less than 5 mm, less than 2 mm, or less than 1 mm. The web may consist of a set of ceramic yarns oriented randomly or in an orderly manner, for example, parallel to each other. The web may consist of a set of ceramic fibers or ceramic yarns entangled or oriented in a preferred manner, for example in a plane, or parallel to a given orientation or to a plurality of favorable orientations.

[0116] Preferably, the web consists of a ceramic yarn made of assembled ceramic fibers, preferably ceramic fibers having one or more of the characteristics of the fibers described above. Such a ceramic yarn typically contains several hundred to several thousand ceramic fibers.

[0117] At least one yarn, preferably a ceramic yarn, preferably more than 90% by number of each ceramic yarn in the web, preferably has a length of more than 10 mm, more than 5 cm, more than 10 cm, more than 30 cm or more than 1 m, and / or preferably less than 10,000 m, less than 5,000 m, less than 1,000 m, less than 100 m, less than 50 m or less than 10 m.

[0118] In one embodiment, the support consists of a single web. In one embodiment, the support may consist of multiple webs of the same or different structure, preferably more than two webs and / or preferably less than ten webs, preferably less than eight webs, where the webs are superimposed on one another. Preferably, each web consists of the yarn.

[0119] In one embodiment, the support includes a lower, preferably nonwoven, web and an upper, preferably nonwoven, web extending over the lower web, each of the lower and upper webs including a plurality of yarns, preferably the yarns, oriented parallel to the orientations of the lower and upper webs, such that the orientations of the lower and upper webs form an angle between them, preferably greater than 15°, greater than 30°, greater than 50°, for example, about 90°.

[0120] In one embodiment, the support is in the form of a single yarn, that is, a single yarn that is not assembled with other yarns.

[0121] In one embodiment, particularly when the support is amorphous silica yarn, the ceramic particles are preferably selected to have a Na2O+K2O content of less than 0.5%, preferably less than 0.1%, and / or the other components, in particular the dispersant, are substantially free of sodium and / or potassium.

[0122] The application of the gelling liquid to the ceramic fibers of the support can be carried out by impregnation, particularly when the support is in the form of a single web or a superposition of multiple webs. Impregnation is also possible when the support is in the form of yarn. The gelling liquid then penetrates the support.

[0123] The impregnation may be carried out according to any technique known to those skilled in the art, in particular by doctoring (or "doctor blade"), by tape casting, by dipping (e.g., by dip coating), by gun, by brush, or by screen printing.

[0124] If the support includes several superimposed webs, each web may be impregnated before being superimposed on the other webs. Alternatively, the web may be superimposed on the other webs without impregnation, and then all the superimposed webs are impregnated simultaneously. Preferably, if the support includes several superimposed webs, each web is impregnated before being superimposed on the other webs.

[0125] The gelling liquid can also be applied to the ceramic fibers of the support without the gelling liquid penetrating the bulk of the support. In particular, the gelling liquid can be applied only to the surface of the support in the form of a ceramic yarn.

[0126] Preferably, during the application of the gelling liquid, the support is maintained at a temperature higher than the gelling temperature of the gelling liquid, preferably 5°C, 10°C, or 20°C higher than the gelling temperature of the gelling liquid. To achieve this objective, the support may be placed, for example, on a heated plate in a heated mold, or heated using a radiant heater.

[0127] The gellable liquid impregnates all or part of the fibrous support.

[0128] Preferably, the support is a single yarn, a yarn web, a yarn braid, a yarn knit, or a fiber entanglement, and more than 50%, preferably more than 60%, preferably more than 70%, preferably more than 80%, preferably more than 90%, preferably more than 95%, preferably 100% of the yarn, or more than 20%, preferably more than 50%, preferably more than 60%, preferably more than 70%, more than 80%, more than 90%, preferably more than 95%, preferably 100% of their outer surface is coated with a gelling liquid.

[0129] In step 3), the gellable liquid is cooled to a temperature lower than its gelation temperature, preferably 5°C, 10°C, or 20°C lower than the gelation temperature of the gellable liquid, in order to convert the gellable liquid into a liquefyable gel.

[0130] The temperature and duration of step 3) are preferably adjusted so that more than 90%, more than 95%, preferably 100%, of the gellable liquid gels, in terms of mass percentage.

[0131] Therefore, a prepreg according to the present invention is obtained.

[0132] The gelation temperature varies depending on the hydrophilic colloid. Preferably, the gelation temperature is greater than 20°C, preferably greater than 25°C, preferably greater than 30°C, and preferably less than 60°C, preferably less than 50°C, preferably less than 45°C, and preferably less than 40°C.

[0133] Preferably, a simple cooling to ambient temperature allows the gellable liquid to gel. In this case, the prepreg can be stored at ambient temperature without the liquefaction of the liquefyable gel.

[0134] Cooling may also be carried out in a refrigerated cell to accelerate the gelation process.

[0135] This does not result in any alteration of the composition. Therefore, the composition of the liquefiable gel is identical to that of the gellable liquid.

[0136] Preferably, the prepreg has a dry feel.

[0137] In optional step 4), the prepreg according to the present invention is stored.

[0138] Preferably, after step 3), the prepreg is stored and / or placed in an airtight bag for less than one month, preferably less than 15 days, preferably less than 5 days, preferably less than 1 day. Preferably, between the end of step 3) and step 4), the prepreg does not undergo any drying other than natural evaporation. In particular, the prepreg does not undergo any drying by heating. Preferably, the volumetric water content of the prepreg at the time it is stored in the airtight bag or packaged is more than 95%, preferably more than 98%, and preferably substantially equal to 100%, of the volumetric water content at the end of step 3). Advantageously, the addition of water required to produce the ceramic matrix component is limited or even zero.

[0139] The prepreg can be stored for, for example, more than one month, more than two months, more than three months, more than six months, or more than one year, and / or preferably less than five years.

[0140] The gelled form is advantageous in that it allows the liquefiable gel to be fixed to the support, in particular, preventing the liquefiable gel from flowing between or along the ceramic fibers of the support. In addition, the gelled form is advantageous in that it allows the ceramic particles and any components, particularly any metal particles, to be fixed to water. Thus, the spatial distribution of the ceramic particles and the arbitrary components remains homogeneous, thereby resulting in a ceramic matrix component, particularly CMC, which also has homogeneous properties.

[0141] The amount of thermoreversible hydrophilic colloid in the gelling liquid of step 1) is adapted according to the desired storage period and desired gel strength. Simple tests can be used to evaluate the gelling ability of the thermoreversible hydrophilic colloid and its ability to be maintained precisely on the support during the desired storage period.

[0142] For example, if the gellable liquid contains gelatin, the amount of gelatin may be increased and / or gelatin with a higher bloom value may be used if the resulting liquefiable gel is not sufficiently strong.

[0143] The following test may be used to evaluate the ability of a gellable liquid to form a liquefyable gel. 50 ml of the gellable liquid is placed in a plastic beaker having a diameter equal to 50 mm and a height equal to 50 mm. The beaker is placed in a cooling cell at a temperature lower than the gelling temperature of the gellable liquid for a sufficient amount of time to gel all of the gellable liquid. The beaker is then removed from the cell and inverted. In one embodiment, if the flow of the liquefyable gel ceases after 1 minute, the gellable liquid is considered satisfactory. Otherwise, as described above, the amount of thermoreversible hydrophilic colloid is increased, and / or the thermoreversible hydrophilic colloid is replaced with a thermoreversible hydrophilic colloid that produces a stronger gel.

[0144] When multiple prepregs are stored together, it is preferable to place an intermediate layer made of a material that prevents any bonding between different prepregs, for example, those made from polymers. For example, a film made from polyester, polyethylene, or polyethylene terephthalate, such as Mylar, may be placed to separate the stacked prepregs.

[0145] Preferably, such an intermediate layer is also inserted between each web of a given prepreg, or, in particular, between two layers of a given prepreg that could be in contact without this intermediate layer if the prepreg is folded or wound into a roll.

[0146] Before storage, each prepreg or set of prepregs is preferably placed in an airtight bag, thereby advantageously limiting its degradation over time, particularly as a result of drying.

[0147] Advantageously, prepregs according to the present invention can be stored at ambient temperature for extended periods with virtually no decomposition.

[0148] In a preferred embodiment, a method according to the present invention for manufacturing a prepreg has the following priorities: In step 1), the gellable liquid is A volume percentage of the gelatable liquid, comprising more than 25% and less than 55%, of ceramic particles (selected from particles in which more than 90% of the mass consists of one or more oxides, particles in which more than 90% of the mass consists of one or more nitrides, particles in which more than 90% of the mass consists of one or more carbides, particles in which more than 90% of the mass consists of one or more borides, and mixtures thereof), The overall size of the ceramic particles is less than 5 μm and greater than 0.1 μm in median diameter D. 50 , and the 99th percentile of less than 50 μm, i.e., D 99 (to show), and A thermoreversible hydrophilic colloid in an amount greater than 0.4% and less than 9% by mass, based on the ceramic particles. (The thermoreversible hydrophilic colloid is selected from gelatin, agar, a mixture of carrageenan and a compound providing sodium cations and / or potassium cations and / or calcium cations, a mixture of furcellaria and sugar, a mixture of konjac gum and xanthan gum in a mass ratio greater than 0.8 and less than 1.2, a mixture of locust bean gum and xanthan gum in a mass ratio greater than 0.67 and less than 1.5, and a mixture of chitosan and pectin in which the mass ratio of pectin to the amount of chitosan is greater than 0.2 and less than 0.8, and the thermoreversible hydrophilic colloid is preferably gelatin), and A quantity of more than 0.1% and less than 6% by mass, based on the mass of the ceramic particles, of other organic components (selected from dispersants, binders, biocides, defoamers, thickeners, plasticizers, drying regulators, and mixtures thereof), Remaining water up to 100% It consists of, In step 2), More than 90% of the ceramic fibers of the support, which may be optionally assembled in the form of yarn, Lengths exceeding 10 mm, and Equivalent diameter greater than 2 μm and less than 50 μm, measured at half the total length. It has, The ceramic fibers, which may be optionally assembled in the form of yarn, constitute more than 90% of the mass of the support, and the fibers, which may be optionally assembled in the form of yarn, consist of one or more oxides and / or one or more nitrides and / or one or more carbides and / or one or more borides and / or carbon, The support is a single yarn, a yarn web, a yarn braid, a yarn knit, or an entanglement of fibers, wherein more than 50% of the yarn, or more than 50% of the number of the yarns or fibers, has their outer surface coated with a gelling liquid. In step 3), The temperature and duration of step 3) are adapted so that more than 90% of the gellable liquid gels, and the gellable liquid is selected to have a gelling temperature of more than 20°C.

[0149] In this preferred embodiment, the gellable liquid does not contain metal particles or precursors of such particles.

[0150] In one embodiment, a method according to the present invention for manufacturing a prepreg has the following priorities: In step 1), the gellable liquid is A volume percentage of the gelatable liquid, comprising more than 25% and less than 55%, of ceramic particles (selected from particles in which more than 90% of the mass consists of one or more oxides, particles in which more than 90% of the mass consists of one or more nitrides, particles in which more than 90% of the mass consists of one or more carbides, particles in which more than 90% of the mass consists of one or more borides, and mixtures thereof, wherein the total volume of the ceramic particles has a median diameter D of less than 5 μm and greater than 0.1 μm. 50 , and the 99th percentile of less than 50 μm, i.e., D 99 (to show), and A volume percentage of the gelatable liquid, consisting of more than 0.5% and less than 9% of metal particles. (The total of the ceramic particles and metal particles has a median diameter D of less than 5 μm and greater than 0.1 μm by volume.) 50 , and the 99th percentile of less than 50 μm, i.e., D 99 (to show), and A thermoreversible hydrophilic colloid in an amount greater than 0.4% and less than 9% as a mass percentage based on the sum of the mass of the ceramic particles and the mass of the metal particles (the thermoreversible hydrophilic colloid is selected from gelatin, agar, a mixture of carrageenan and a compound providing sodium cations and / or potassium cations and / or calcium cations, a mixture of furcellaria and sugar, a mixture of konjac gum and xanthan gum in a mass ratio greater than 0.8 and less than 1.2, a mixture of locust bean gum and xanthan gum in a mass ratio greater than 0.67 and less than 1.5, and a mixture of chitosan and pectin in which the mass ratio of pectin to the amount of chitosan is greater than 0.2 and less than 0.8, and the thermoreversible hydrophilic colloid is preferably gelatin), and A mass percentage of more than 0.1% and less than 6% of other organic components (the other organic components are selected from dispersants, binders, biocides, defoamers, thickeners, plasticizers, drying regulators and mixtures thereof), based on the sum of the mass of the ceramic particles and the mass of the metal particles. Remaining water up to 100% It consists of, In step 2), More than 90% of the ceramic fibers of the support, which may be optionally assembled in the form of yarn, Lengths exceeding 10 mm, and Equivalent diameter greater than 2 μm and less than 50 μm, measured at half the total length. It has, The ceramic fibers, which may be optionally assembled in the form of yarn, constitute more than 90% of the mass of the support, and the fibers, which may be optionally assembled in the form of yarn, consist of one or more oxides and / or one or more nitrides and / or one or more carbides and / or one or more borides and / or carbon, The support is a single yarn, a yarn web, a yarn braid, a yarn knit, or an entanglement of fibers, wherein more than 50% of the yarn, or more than 50% of the number of the yarns or fibers, has their outer surface coated with a gelling liquid. In step 3), The temperature and duration of step 3) are adapted so that more than 90% of the gellable liquid gels, and the gellable liquid is selected to have a gelling temperature of more than 20°C.

[0151] In a preferred embodiment, a method according to the present invention for manufacturing a prepreg has the following priorities: In step 1), the gellable liquid is The amount of ceramic particles, as a volume percentage of the volume of the gelatable liquid, is greater than 30% and less than 50% (more than 95% by volume of the ceramic particles consists of more than 99% of their mass of one or more oxides, and the chemical analysis shows that the mass percentage based on the oxides is Al2O3+SiO2≧95%). The overall size of the ceramic particles is less than 5 μm and greater than 0.1 μm in median diameter D. 50 , and the 99th percentile of less than 50 μm, i.e., D 99 (to show), and A thermoreversible hydrophilic colloid (the thermoreversible hydrophilic colloid is gelatin) in an amount greater than 0.5% and less than 4% of the mass of the ceramic particles, and A quantity of more than 0.1% and less than 6% by mass, based on the mass of the ceramic particles, of other organic components (selected from dispersants, binders, biocides, defoamers, thickeners, plasticizers, drying regulators, and mixtures thereof), Remaining water up to 100% It consists of, In step 2), More than 90% of the ceramic fibers of the support, which may be optionally assembled in the form of yarn, Lengths exceeding 10 mm, and Equivalent diameter greater than 2 μm and less than 30 μm, measured at half the total length. It has, The ceramic fibers, which may be optionally assembled in the form of yarn, constitute more than 90% of the mass of the support. The fiber, which may be optionally assembled into a yarn form, shows a chemical analysis in which more than 95% of its mass consists of one or more oxides, and the mass percentage based on the oxides is Al2O3+SiO2≧95%. The support is a single yarn, a yarn web, a yarn braid, a yarn knit, or an entanglement of fibers, wherein more than 50% of the yarn, or more than 50% of the number of the yarns or fibers, has their outer surface coated with a gelling liquid. In step 3), The temperature and duration of step 3) are preferably adapted so that more than 90% of the gellable liquid gels by mass percentage, and the gellable liquid is selected to have a gelling temperature of more than 20°C.

[0152] This preferred embodiment does not include metal particles or precursors of such particles.

[0153] Preferably, the prepreg according to the present invention is manufactured according to the manufacturing method according to the present invention.

[0154] Method for manufacturing ceramic matrix components A method for producing a ceramic matrix component according to the present invention comprises steps 5) to 9) described above, wherein steps 7) and 9) are optional.

[0155] In step 5), at least one prepreg according to the present invention, preferably manufactured according to a preceding step, is removed from its bag where appropriate, and is then optionally heated after the initial partial molding so that the temperature of at least a portion, preferably all, of the liquefiable gel reaches, and preferably exceeds, the liquefaction temperature of the liquefiable gel.

[0156] In one embodiment, a plurality of prepregs according to the present invention are simultaneously heated, for example, after one prepreg is superimposed on another, so that the temperature of at least some, preferably all, of the liquefiable gel reaches, and preferably exceeds, the liquefaction temperature of the liquefiable gel.

[0157] The heating is preferably carried out at a temperature of less than 80°C, preferably less than 70°C, preferably less than 60°C, and preferably less than 50°C.

[0158] The yarn-form prepreg can take the form of a single roll of yarn. The yarn can be heated only locally to the extent necessary to unravel it.

[0159] Next, the prepreg becomes easily deformable, like a prepreg in the prior art.

[0160] Notably, the prepreg does not significantly decompose when temporarily stored at ambient temperature before heating. However, preferably, this temporary storage is continued for less than 48 hours, and more preferably less than 24 hours.

[0161] In one embodiment, the prepreg may be wetted before step 6).

[0162] The high water content in the prepreg is advantageous because it allows for limiting the addition of water, thereby simplifying the manufacturing process. In addition, the water in the prepreg is advantageously distributed more uniformly within the prepreg than any water that could be added to wet the prepreg. The mechanical properties of the ceramic matrix components are thus improved.

[0163] Preferably, the addition of water resulting from this wetting is less than 20%, preferably less than 10%, and preferably less than 5%, of the water content of the prepreg by volume of the liquefiable gel.

[0164] Preferably, the prepreg is not wetted.

[0165] In step 6), the prepreg, which has been made deformable in a preceding step, is molded according to a desired geometric structure in accordance with any technique known to those skilled in the art in order to obtain a deformable preform.

[0166] Preferably, the prepreg is formed by being compressed on a mold.

[0167] Multiple prepregs, preferably more than two and preferably less than ten, that have been made deformable in a preceding process may be molded in step 6). Preferably, each prepreg takes the form of a single web or multiple overlapping webs.

[0168] Conventionally, the multiple prepregs prepared in step 5) are molded simultaneously, for example, after one prepreg is superimposed on another, or are applied to the mold sequentially in superimposition. The molding may include, in particular, stacking and then laminating the multiple prepregs, or, in particular, if the prepregs take the form of a single web or multiple superimposed webs, stacking and then autoclaving the multiple prepregs.

[0169] The forming of a prepreg in the form of yarn can also be achieved by locally heating the prepreg and then winding it up.

[0170] Prepregs in yarn form can, in particular, be temporarily wound around a base, or otherwise wound around a core, for example, having a circular, elliptical, or polygonal cross-section. This operation is called filament winding.

[0171] The base may be temporary or permanent, depending on whether it is subsequently separated from the wound yarn. The number of rotations around the base may be greater than 5, greater than 50, greater than 500, greater than 5000 and / or preferably less than 1,000,000 or less than 100,000. In one embodiment, winding the yarn gives the yarn a tubular shape. In one embodiment, the tubular shape may be cut, for example, along a generatrix and unfolded, for example, to obtain a planar shape.

[0172] Alternatively, the forming of a prepreg in the form of yarn may result from localized heating of the prepreg, deposition on a surface, and then application of pressure, which may be simultaneous with heating and / or application of pressure.

[0173] Prepregs in the form of yarn can be unwound onto an open surface, such as a planar surface. This operation is called filament placement. This filament placement can be carried out by a 3D printer. The unwound yarn can move back and forth on the surface, overlapping or not overlapping (juxtaposed), like grooves dug with a plow. In one embodiment, this yarn placement results in a planar shape.

[0174] Steps 5) and 6) may be performed simultaneously, as described in particular in the following examples.

[0175] In an optional step 7), the deformable preform, which consists of one or more prepregs according to the present invention obtained from a preceding step, is cooled such that the temperature of at least a portion, preferably all, of the gellable liquid reaches, and preferably falls below, the gelling temperature of the gellable liquid.

[0176] The deformable preform hardens and becomes a "cured" preform, which, advantageously, facilitates the handling of the preform.

[0177] Naturally, the cured preform can retain a certain degree of deformability. However, this deformability is lower than that of the deformable preform.

[0178] Preferably, the method does not include step 7).

[0179] In step 8), the deformable (i.e., without step 7) or cured (i.e., with step 7) preform is dried. Any technique known to those skilled in the art may be used.

[0180] Preferably, if step 7) is performed, the drying is carried out at a drying temperature below the liquefaction temperature of the liquefiable gel, for example, by drying under vacuum. Thus, the cured preform remains rigid.

[0181] Preferably, if step 7) is not performed, the drying is carried out at a temperature higher than the gelling temperature of the gellable liquid.

[0182] The drying process removes at least some of the water, thereby curing the deformable preform without a special step to gel the gellable liquid.

[0183] When the thermoreversible hydrophilic colloid is gelatin, drying at a temperature equal to 50°C and a relative humidity equal to 30% for a period of preferably 0.5 to 12 hours is well suitable.

[0184] This drying process yields the ceramic matrix component.

[0185] In an optional and preferred step 9), the ceramic matrix component obtained from the preceding step is sintered. Next, the ceramic matrix component becomes a CMC.

[0186] Those skilled in the art know how to determine sintering conditions depending on the properties of the ceramic particles, the arbitrary metal particles, and the ceramic fibers.

[0187] In particular, when the ceramic fiber is made from an oxide, and when the ceramic particles show a chemical analysis indicating SiO2 ≥ 90%, the sintering temperature is preferably greater than 800°C and preferably less than 1000°C, the sintering is preferably carried out under air and preferably at a pressure of 1 bar, and the holding time of the stationary phase is preferably greater than 1 hour and preferably less than 10 hours.

[0188] In particular, when the ceramic fiber is made from an oxide, and when the ceramic particles show a chemical analysis indicating Al2O3 ≥ 90%, the sintering temperature is preferably greater than 1000°C and preferably less than 1300°C, the sintering is preferably carried out under air and preferably at a pressure of 1 bar, and the holding time of the stationary phase is preferably greater than 1 hour and preferably less than 10 hours.

[0189] In particular, when the ceramic fiber is made from carbides and / or borides and / or nitrides and / or carbon, and when the ceramic particles are made from carbides and / or borides and / or nitrides and / or carbon, the sintering temperature is preferably above 1400°C and preferably below 2300°C, the sintering is preferably carried out in a neutral, reducing or reactive atmosphere and preferably at a pressure of 1 bar, and the stationary phase holding time is preferably above 1 hour and preferably below 10 hours.

[0190] The CMC can be used in particular in the following applications: hot drive rollers for high-temperature exhaust gas components, firing supports, insulating materials, and high-temperature glass components.

[0191] However, the prepregs according to the present invention are not limited to the manufacture of CMC, but can be used, for example, to manufacture other ceramic matrix components, in particular thermal insulators, especially conformable thermal insulators, i.e., those that can conform to the shape of an object to be protected from heat.

[0192] prepreg The features, and particularly preferred features, of the prepreg according to the present invention will become directly apparent from the preceding description of the method.

[0193] In particular, in the liquefiable gel, the ceramic particles, the metal particles, the precursors of the ceramic particles and the precursors of the metal particles Quantity, a particularly preferred quantity, Composition, particularly preferred composition, Median diameter, particularly preferred median diameter, 99th percentile (D99 ), particularly preferred 99th percentile, Particle size distribution, particularly preferred particle size distribution This is the same as described above for the gellable liquid, The thermoreversible hydrophilic colloid of the liquefiable gel Quantity, a particularly preferred quantity, Composition, particularly preferred composition, Gelation temperature, particularly preferred gelation temperature This is the same as described above for the gellable liquid, The “other components” Quantity, a particularly preferred quantity, Composition, particularly preferred composition, This is the same as described above for the gellable liquid, Multiple fibers and multiple yarns of the support Quantity, a particularly preferred quantity, Composition, particularly preferred composition, Dimensions, especially preferred dimensions The method for producing the ceramic matrix component is the same as described above. The outer surface portions of the multiple fibers and multiple yarns of the support, which are coated with a liquefiable gel, are the same as described above for the outer surface portions of the multiple fibers and multiple yarns of the support, which are coated with a gellable liquid. The support Shape, particularly preferred shape, Structure, for example, the orientation of yarns in different superimposed webs and the number of webs, a particularly preferred structure, Dimensions, especially preferred dimensions The method for producing the ceramic matrix component is the same as described above. The packing of the prepreg, particularly the addition and packaging of the intermediate layer, is the same as described above for the method of producing the ceramic matrix component.

[0194] The water in the liquefiable gel is preferably desalinated water.

[0195] In a preferred embodiment, the prepreg according to the present invention has the following priorities: The liquefiable gel is A volume percentage of the liquefiable gel, comprising more than 25% and less than 55%, of ceramic particles (selected from particles in which more than 90% of the mass consists of one or more oxides, particles in which more than 90% of the mass consists of one or more nitrides, particles in which more than 90% of the mass consists of one or more carbides, particles in which more than 90% of the mass consists of one or more borides, and mixtures thereof). The overall size of the ceramic particles is less than 5 μm and greater than 0.1 μm in median diameter D. 50 , and the 99th percentile of less than 50 μm, i.e., D 99 (to show), and A thermoreversible hydrophilic colloid in an amount greater than 0.4% and less than 9% of the mass of the ceramic particles, based on the mass percentage. (The thermoreversible hydrophilic colloid is selected from gelatin, agar, a mixture of carrageenan and a compound providing sodium cations and / or potassium cations and / or calcium cations, a mixture of furcellaria and sugar, a mixture of konjac gum and xanthan gum in a mass ratio greater than 0.8 and less than 1.2, a mixture of locust bean gum and xanthan gum in a mass ratio greater than 0.67 and less than 1.5, and a mixture of chitosan and pectin in which the mass ratio of pectin to the amount of chitosan is greater than 0.2 and less than 0.8, and the thermoreversible hydrophilic colloid is preferably gelatin), and A quantity of more than 0.1% and less than 6% by mass, based on the mass of the ceramic particles, of other organic components (selected from dispersants, binders, biocides, defoamers, thickeners, plasticizers, drying regulators, and mixtures thereof), Remaining water up to 100% It consists of, More than 90% of the ceramic fibers of the support, which may be optionally assembled in the form of yarn, Lengths exceeding 10 mm, and Equivalent diameter greater than 2 μm and less than 50 μm, measured at half the total length. It has, The ceramic fibers, which may be optionally assembled in the form of yarn, constitute more than 90% of the mass of the support, and the fibers, which may be optionally assembled in the form of yarn, consist of one or more oxides and / or one or more nitrides and / or one or more carbides and / or one or more borides and / or carbon, The support is a single yarn, a yarn web, a yarn braid, a yarn knit, or an entanglement of fibers, wherein more than 50% of the yarn, or more than 50% of the number of yarns or fibers, are coated with a liquefiable gel on more than 50% of their outer surface.

[0196] In this preferred embodiment, the liquefiable gel does not contain metal particles or precursors of such particles.

[0197] In one embodiment, a prepreg according to the present invention has the following priority: The liquefiable gel is A volume percentage of the liquefiable gel, comprising more than 25% and less than 55%, of ceramic particles (selected from particles in which more than 90% of the mass consists of one or more oxides, particles in which more than 90% of the mass consists of one or more nitrides, particles in which more than 90% of the mass consists of one or more carbides, particles in which more than 90% of the mass consists of one or more borides, and mixtures thereof, wherein the total volume of the ceramic particles has a median diameter D of less than 5 μm and greater than 0.1 μm. 50 , and the 99th percentile of less than 50 μm, i.e., D 99 (to show), and A quantity of metal particles, in volume percentage of the liquefiable gel, that is greater than 0.5% and less than 9%. (The total of the ceramic particles and metal particles has a median diameter D of less than 5 μm and greater than 0.1 μm by volume.) 50 , and the 99th percentile of less than 50 μm, i.e., D 99(to show), and A thermoreversible hydrophilic colloid in an amount greater than 0.4% and less than 9% as a mass percentage based on the sum of the mass of the ceramic particles and the mass of the metal particles (the thermoreversible hydrophilic colloid is selected from gelatin, agar, a mixture of carrageenan and a compound providing sodium cations and / or potassium cations and / or calcium cations, a mixture of furcellaria and sugar, a mixture of konjac gum and xanthan gum in a mass ratio greater than 0.8 and less than 1.2, a mixture of locust bean gum and xanthan gum in a mass ratio greater than 0.67 and less than 1.5, and a mixture of chitosan and pectin in which the mass ratio of pectin to the amount of chitosan is greater than 0.2 and less than 0.8, and the thermoreversible hydrophilic colloid is preferably gelatin), and A mass percentage of more than 0.1% and less than 6% based on the sum of the mass of the ceramic particles and the mass of the metal particles, of other organic components (the other organic components are selected from dispersants, binders, biocides, defoamers, thickeners, plasticizers, drying regulators and mixtures thereof), and Remaining water up to 100% It consists of, More than 90% of the ceramic fibers of the support, which may be optionally assembled in the form of yarn, Lengths exceeding 10 mm, and Equivalent diameter greater than 2 μm and less than 50 μm, measured at half the total length. It has, The ceramic fibers, which may be optionally assembled in the form of yarn, constitute more than 90% of the mass of the support, and the fibers, which may be optionally assembled in the form of yarn, consist of one or more oxides and / or one or more nitrides and / or one or more carbides and / or one or more borides and / or carbon, The support is a single yarn, a yarn web, a yarn braid, a yarn knit, or an entanglement of fibers, wherein more than 50% of the yarn, or more than 50% of the number of yarns or fibers, are coated with a liquefiable gel on more than 50% of their outer surface.

[0198] In a preferred embodiment, the prepreg according to the present invention has the following priorities: The liquefiable gel is A quantity of ceramic particles, in volume percentage of the liquefiable gel, that is greater than 30% and less than 50%. (Chemical analysis shows that more than 95% by volume of the ceramic particles consists of more than 99% of its mass of one or more oxides, and that Al2O3+SiO2 ≥ 95% as a mass percentage based on the oxides.) The overall size of the ceramic particles is less than 5 μm and greater than 0.1 μm in median diameter D. 50 , and the 99th percentile of less than 50 μm, i.e., D 99 (to show), and A thermoreversible hydrophilic colloid (the thermoreversible hydrophilic colloid is gelatin) in an amount greater than 0.5% and less than 4% of the mass of the ceramic particles, and A quantity of more than 0.1% and less than 6% by mass, based on the mass of the ceramic particles, of other organic components (selected from dispersants, binders, biocides, defoamers, thickeners, plasticizers, drying regulators, and mixtures thereof), Remaining water up to 100% It consists of, More than 90% of the ceramic fibers of the support, which may be optionally assembled in the form of yarn, Lengths exceeding 10 mm, and Equivalent diameter greater than 2 μm and less than 30 μm, measured at half the total length. It has, The ceramic fibers, which may be optionally assembled in the form of yarn, constitute more than 90% of the mass of the support. The ceramic fiber, which may be optionally assembled in the form of a yarn, has a chemical analysis showing that more than 95% of its mass consists of one or more oxides, and that Al2O3+SiO2 ≥ 95% as a mass percentage based on the oxides. The support is a single yarn, a yarn web, a yarn braid, a yarn knit, or an entanglement of fibers, wherein more than 50% of the yarn, or more than 50% of the number of yarns or fibers, are coated with a liquefiable gel on more than 50% of their outer surface.

[0199] In this preferred embodiment, the liquefiable gel does not contain metal particles or precursors of such particles.

[0200] Examples The following non-limiting examples are given for illustrative purposes of the present invention.

[0201] Manufacturing protocol The following starting materials are used: As a thermoreversible hydrophilic colloid, gelatin, sold by Weishardt International, has a bloom value equal to 280 and completely passes through a square mesh sieve with an opening equal to 0.841 mm. As a chemical agent for adjusting the pH, an aqueous solution of ammonium hydroxide (NH4OH) with a concentration equal to 20% by mass, As a precursor for ceramic particles, a solution of colloidal silica, namely LUDOX AS40, As ceramic particles, amorphous silica powder having a purity of over 99.9% by mass, a median diameter equal to 1.4 μm, and a 99th percentile equal to 4 μm. As a binder, polyethylene glycol PEG4000 is provided in liquid form having a PEG4000 concentration equal to 50% by mass, with the remainder being water. As a fibrous support, 200 g / m 2A 1 / 5 satin fabric made from Quartzel® yarn having a base weight equal to (the yarn is supported by reference C14 80 Z0 QS1318 sold by Saint-Gobain Quartz. The fabric has been heat-treated in an electric oven for the purpose of desizing the yarn before use, the heat treatment consisting of rising to 550°C at a rate equal to 100°C / min, stationary phase at 550°C for 1 hour, and natural temperature decrease).

[0202] In step 1) 20 g of gelatin is swollen in 200 g of water having a resistivity higher than 17 MΩ·cm at ambient temperature for 5 minutes, and then the whole mixture is brought to a temperature equal to 65°C for 5 minutes to completely dissolve the gelatin. Next, the pH is adjusted to a value equal to 9 by adding ammonium hydroxide solution, and then the temperature of the suspension is lowered and maintained at a temperature equal to 50°C.

[0203] Next, a gellable liquid is prepared as follows.

[0204] 170g of amorphous silica powder, 75g of LUDOX AS40, 55g of water, 4g of PEG4000, 100g of alumina bead powder with a median diameter equal to 6mm, and 100g of alumina bead powder with a median diameter equal to 10mm are placed in a jar with a volume equal to 0.5 liters. The jar is closed and then rotated in a fixed position on a jar mill at a rotational speed equal to 50 rpm for 12 hours.

[0205] Next, the beads are removed, and the resulting suspension is brought to a temperature equal to 50°C. The gelling liquid, intended to impregnate the quartz yarn fabric, is prepared by mixing the suspension and 33.3 g of gelatin suspension prepared in step 1) with a spatula. The gelling liquid thus obtained, having the composition described in Table 1, is maintained at a temperature of 50°C.

[0206]

Table 1

[0207] In step 2) The satin fabric of Quartzel (trademark) yarn sized 80 mm × 80 mm is flattened and spread on a glass sheet preheated to a temperature equal to 50°C. The gellable liquid, still at a temperature equal to 50°C, obtained at the end of step 2) is poured onto the fabric and then spread on the fabric using a plastic spatula. Next, the fabric is turned over, the gellable liquid is poured onto the fabric at a temperature equal to 50°C, and then spread using a plastic spatula.

[0208] A plastic film is placed on each of the major surfaces of the impregnated fabric thus obtained. Next, the whole is placed and sealed inside a sealed plastic bag. Step 2) is repeated to obtain four fabrics of Quartzel (trademark) yarn impregnated with the gellable liquid obtained at the end of step 1).

[0209] In step 3) The plastic bag is placed in a cell at 6°C for 12 hours to gel the gellable liquid and obtain prepregs according to the invention in the form of four prepregs, and the prepregs are stored in the cell until their use.

[0210] In step 4) The plastic bag is taken out of the cell and stored at ambient temperature for 180 days. <00009​​​​​​​First, the first prepreg is placed flat on a glass sheet preheated to 50°C. Next, the second prepreg is placed on top of the first prepreg, with the yarn of the second prepreg oriented at an angle equal to 90° to the yarn of the first prepreg. The two prepregs are smoothed using a plastic spatula. Next, the third prepreg is placed on top of the second prepreg, with the yarn of the third prepreg oriented in the same direction as the second prepreg, and the third prepreg is flipped over the second prepreg like a pancake. Next, the third prepreg is smoothed over the pair of the first and second prepregs using a plastic spatula. Finally, the yarn of the fourth prepreg is oriented at an angle equal to 90° to the yarn of the third prepreg, so that the fourth prepreg is placed on top of the third prepreg and inverted relative to the second prepreg. The fourth prepreg is smoothed over the set of the first, second, and third prepregs using a plastic spatula. A plastic film is placed on each of the main surfaces of the set of prepregs, and then the whole is placed in an airtight bag. Finally, the bag is placed in a drying oven at 50°C for 1 hour.

[0213] In step 6) The set of prepregs is removed from the bag and immediately smoothed with a plastic spatula to obtain a deformable preform. Each of the main surfaces of the deformable preform is protected with a plastic film.

[0214] The prepreg according to the present invention exhibits good adaptability and good binding properties, particularly after the storage period between manufacturing and use.

[0215] In step 8) The plastic film is removed from one of the main surfaces of the deformable preform, and the deformable preform is dried in a drying oven at 50°C in an atmosphere of 30% relative humidity for 12 hours.

[0216] In step 9)The preform obtained from step 8) is sintered in an electric oven according to the following cycle to obtain a ceramic matrix composite: The temperature is raised from 20°C to 900°C at a rate equal to 10°C / min. Maintain a temperature of 900°C for 1 hour. Allow the temperature to naturally drop to the ambient temperature.

[0217] As is evident herein, the present invention provides a prepreg that enables the production of ceramic matrix components, particularly by drying and / or sintering. The prepreg comprises a gel that adheres effectively to a fiber support and immobilizes the ceramic particles. The gel also allows for water trapping, thereby limiting evaporation. Advantageously, the prepreg can be stored for extended periods without substantially modifying its structure. Therefore, the prepreg remains suitable for the production of ceramic matrix components, particularly CMCs.

[0218] Naturally, the present invention is not limited to the examples and embodiments described above.

Claims

1. A prepreg for forming a CMC, the prepreg comprising a support whose mass is more than 90% ceramic fiber and a thermoreversible liquefiable gel that at least partially covers at least a portion of the ceramic fiber, wherein the liquefiable gel becomes liquid when heated. As a volume percentage of the volume of the liquefiable gel, 20% to 60% ceramic particles, As a volume percentage relative to the volume of the liquefiable gel, 0% to 10% of metal particles, A thermoreversible hydrophilic colloid, as a mass percentage of the total mass of the ceramic particles and the metal particles, is present in an amount of 0.2% to 10%. One or more other components, in mass percentage of 0% to 7% of the total mass of the ceramic particles and the metal particles. Remaining water up to 100% Includes, The thermoreversible hydrophilic colloid of the liquefiable gel is selected from: gelatin; agar; a mixture of carrageenan and a compound that provides sodium cations and / or potassium cations and / or calcium cations; a mixture of furcellaria and sugar; a mixture of konjac gum and xanthan gum; a mixture of locust bean gum and xanthan gum; and a mixture of chitosan and pectin. The one or more other components are organic and selected from dispersants, binders, biocides, defoamers, thickeners, plasticizers, drying regulators, and mixtures thereof. The prepreg, wherein the ceramic particles and metal particles can be partially or entirely replaced by a precursor of ceramic particles and a precursor of metal particles, respectively, by heat treatment at a temperature exceeding 200°C to form the ceramic particles and metal particles.

2. The ceramic particles are present in an amount greater than 25% and less than 55% of the volume of the liquefiable gel, and / or The thermoreversible hydrophilic colloid is present in an amount exceeding 0.4% by mass percentage relative to the total mass of the ceramic particles and the metal particles. The prepreg according to claim 1.

3. The ceramic particles of the liquefiable gel are selected from particles in which more than 90% of the mass consists of one or more oxides, particles in which more than 90% of the mass consists of one or more nitrides, particles in which more than 90% of the mass consists of one or more carbides, particles in which more than 90% of the mass consists of one or more borides, and mixtures thereof. The prepreg according to claim 1 or 2.

4. The thermoreversible hydrophilic colloid of the liquefiable gel is selected from: gelatin; agar; a mixture of carrageenan and a compound providing sodium cations and / or potassium cations and / or calcium cations; a mixture of furcellaria and sugar; a mixture of konjac gum and xanthan gum in a mass ratio greater than 0.8 and less than 1.2; a mixture of locust bean gum and xanthan gum in a mass ratio greater than 0.67 and less than 1.5; and a mixture of chitosan and pectin in which the mass ratio of the amount of pectin to the amount of chitosan is greater than 0.2 and less than 0.

8. The prepreg according to any one of claims 1 to 3.

5. More than 90% by volume of the ceramic particles in the liquefiable gel consists of more than 90% by mass of one or more oxides, and / or The thermoreversible hydrophilic colloid of the liquefiable gel is a mixture of gelatin, chitosan, and pectin. The prepreg according to any one of claims 1 to 4.

6. More than 95% by volume of the ceramic particles consists of more than 99% by mass of one or more oxides, and based on the mass percentage of the oxides, Al ２ O ３ +SiO ２ This shows a chemical analysis result of ≥95%. The prepreg according to claim 5.

7. The support, which may optionally be assembled in the form of a yarn, has more than 90% by number of ceramic fibers having a length greater than 10 mm and an equivalent diameter greater than 2 μm and less than 50 μm, measured at half its total length, and / or The ceramic fiber of the support consists of more than 90% by mass of one or more oxides and / or one or more nitrides and / or one or more carbides and / or one or more borides and / or carbon, and / or The support is a single yarn, a yarn web, a yarn braid, a yarn knit, or a fiber entanglement, and more than 50% of the yarn, or more than 50% of the number of the yarns or the number of the ceramic fibers, are coated with a liquefiable gel on more than 50% of their outer surface. The prepreg according to any one of claims 1 to 6.

8. The ceramic fibers of the support, which may be optionally assembled in the form of yarn, consist of more than 95% of their mass of one or more oxides, and based on the mass percentage of the oxides, Al ２ O ３ +SiO ２ This shows a chemical analysis result of ≥95%. The prepreg according to claim 7.

9. The prepreg according to claim 8, wherein the ceramic fibers of the support, which may optionally be assembled in the form of yarn, are selected from glass fibers, amorphous silica fibers, corundum fibers, mullite fibers, mullite-corundum fibers, and mixtures thereof.

10. The prepreg according to any one of claims 1 to 9, wherein the support consists of a plurality of superimposed webs.

11. In a liquefiable gel, The ceramic particles are present in an amount greater than 25% and less than 55% of the volume of the liquefiable gel, wherein the ceramic particles are selected from particles in which more than 90% of the mass consists of one or more oxides, particles in which more than 90% of the mass consists of one or more nitrides, particles in which more than 90% of the mass consists of one or more carbides, particles in which more than 90% of the mass consists of one or more borides, and mixtures thereof, and the total median diameter D of the ceramic particles is less than 5 μm and greater than 0.1 μm by volume. ５０ , and the 99th percentile of less than 50 μm, i.e., D ９９ This indicates, and also, The thermoreversible hydrophilic colloid is present in an amount greater than 0.4% and less than 9% as a mass percentage based on the mass of the ceramic particles, where the thermoreversible hydrophilic colloid is selected from gelatin; agar; a mixture of carrageenan and a compound providing sodium cations and / or potassium cations and / or calcium cations; a mixture of furcellaria and sugar; a mixture of konjac gum and xanthan gum in a mass ratio greater than 0.8 and less than 1.2; a mixture of locust bean gum and xanthan gum in a mass ratio greater than 0.67 and less than 1.5; and a mixture of chitosan and pectin in which the mass ratio of pectin to the amount of chitosan is greater than 0.2 and less than 0.

8. The other components are present in an amount greater than 0.1% and less than 6% of the mass of the ceramic particles, based on the mass of the ceramic particles. In the support, The support, which may be optionally assembled in the form of yarn, has more than 90% by number of ceramic fibers with a length greater than 10 mm and an equivalent diameter greater than 2 μm and less than 50 μm, measured at half its total length, The ceramic fibers, which may be optionally assembled in the form of yarn, constitute more than 90% of the mass of the support, and more than 90% of the mass of the ceramic fibers, which may be optionally assembled in the form of yarn, consists of one or more oxides and / or one or more nitrides and / or one or more carbides and / or one or more borides and / or carbon. The support is a single yarn, a yarn web, a yarn braid, a yarn knit, or an entanglement of fibers, wherein more than 50% of the single yarn, or more than 50% of the multiple yarns or multiple fibers as a percentage by number, have more than 50% of their outer surface coated with a liquefiable gel. The prepreg according to any one of claims 1 to 10.

12. In the liquefiable gel, The ceramic particles constitute more than 25% and less than 55% of the volume of the liquefiable gel, wherein the ceramic particles are selected from particles in which more than 90% of the mass consists of one or more oxides, particles in which more than 90% of the mass consists of one or more nitrides, particles in which more than 90% of the mass consists of one or more carbides, particles in which more than 90% of the mass consists of one or more borides, and mixtures thereof. The amount of the metal particles is greater than 0.5% and less than 9% of the volume of the liquefiable gel. The entirety of the ceramic particles and the metal particles has a median diameter D greater than 0.1 μm and less than 5 μm by volume ５０ , and a 99th percentile less than 50 μm, i.e., D ９９ is shown, The thermoreversible hydrophilic colloid is present in an amount greater than 0.4% and less than 9% as a mass percentage based on the sum of the mass of the ceramic particles and the mass of the metal particles, selected from gelatin, agar, a mixture of carrageenan and a compound providing sodium cations and / or potassium cations and / or calcium cations, a mixture of furcellaria and sugar, a mixture of konjac gum and xanthan gum in a mass ratio greater than 0.8 and less than 1.2, a mixture of locust bean gum and xanthan gum in a mass ratio greater than 0.67 and less than 1.5, and a mixture of chitosan and pectin in which the mass ratio of the amount of pectin to the amount of chitosan is greater than 0.2 and less than 0.

8. The other components are present in an amount greater than 0.1% and less than 6% of the total mass based on the combined mass of the ceramic particles and the metal particles. In the support, The support, which may be optionally assembled in the form of a yarn, has more than 90% by number of ceramic fibers with a length greater than 10 mm and an equivalent diameter greater than 2 μm and less than 50 μm, measured at half the total length. The ceramic fibers, which may be optionally assembled in the form of yarn, constitute more than 90% of the mass of the support, and more than 90% of the mass of the ceramic fibers, which may be optionally assembled in the form of yarn, consists of one or more oxides and / or one or more nitrides and / or one or more carbides and / or one or more borides and / or carbon. The support is a single yarn, a yarn web, a yarn braid, a yarn knit, or an entanglement of fibers, wherein more than 50% of the single yarn, or more than 50% of the multiple yarns or multiple fibers as a percentage by number, have more than 50% of their outer surface coated with a liquefiable gel. or the prepreg according to any one of claims 1 to 11.

13. The prepreg according to any one of claims 1 to 12, wherein a thermoreversible hydrophilic colloid is present in an amount of less than 7% by mass relative to the total mass of the ceramic particles and the metal particles.

14. In the liquefiable gel, The amount of the ceramic particles is greater than 30% and less than 50% of the volume of the liquefiable gel. More than 95% by volume of the ceramic particles consists of more than 99% by mass of one or more oxides, and based on the mass percentage of the oxides, Al ２ O ３ +SiO ２ The chemical analysis shows that it is ≥95%. and, The overall size of the ceramic particles has a median diameter D of less than 5 μm and greater than 0.1 μm by volume. ５０ , and the 99th percentile of less than 50 μm, i.e., D ９９ This indicates, and also, The thermoreversible hydrophilic colloid is present in an amount greater than 0.5% and less than 4% of the mass of the ceramic particles, where the thermoreversible hydrophilic colloid is gelatin, and The other components are present in an amount greater than 0.1% and less than 6% of the mass of the ceramic particles, and, In the support, The support, which may be optionally assembled in the form of a yarn, has more than 90% by number of ceramic fibers, with a length greater than 10 mm and an equivalent diameter greater than 2 μm and less than 30 μm, measured at half its total length, The ceramic fibers, which may be optionally assembled in the form of yarn, account for more than 90% of the mass of the support, and The ceramic fiber, which may be optionally assembled in the form of a yarn, consists of more than 95% by mass of one or more oxides, and the mass percentage based on the oxides is Al ２ O ３ +SiO ２ The chemical analysis shows that it is ≥95%. The support is a single yarn, a yarn web, a yarn braid, a yarn knit, or an entanglement of fibers, wherein more than 50% of the yarn, or more than 50% of the number of the yarns or fibers, has its outer surface coated with a liquefiable gel. The prepreg according to any one of claims 1 to 10.

15. The metal particles are present in an amount greater than 0.5% and less than 9% of the volume of the liquefiable gel, and / or One or more other components are present in an amount greater than 0.5% and less than 6% of the total mass of the ceramic particles and the metal particles. The prepreg according to any one of claims 1 to 14.

16. The prepreg according to claim 15, wherein the amount of the thermoreversible hydrophilic colloid is greater than 0.5% and less than 4% by mass relative to the total mass of the ceramic particles and the metal particles.

17. The prepreg according to any one of claims 1 to 16, wherein the ratio of the amount of the "other components" to the mass of the thermoreversible hydrophilic colloid is less than 1, and the amount of the thermoreversible hydrophilic colloid and the amount of the "other components" are expressed as a mass percentage of the total mass of the ceramic particles and the metal particles.

18. The prepreg according to claim 17, wherein the ratio is less than 0.

6.

19. A prepreg according to any one of claims 1 to 18, contained in an airtight bag.

20. A method for producing a prepreg that forms a CMC, 1) Prepare a gellable liquid having the following composition: The ceramic particles constitute 20% to 60% of the volume of the gelatable liquid, As a volume percentage relative to the volume of the gelable liquid, 0% to 10% of metal particles, A thermoreversible hydrophilic colloid, as a mass percentage of the total mass of the ceramic particles and the metal particles, is present in an amount of 0.2% to 10%. One or more other components, in mass percentage of 0% to 7% of the total mass of the ceramic particles and the metal particles. Remaining water up to 100%, The thermoreversible hydrophilic colloid is selected from gelatin; agar; a mixture of carrageenan and a compound providing sodium cations and / or potassium cations and / or calcium cations; a mixture of furcellaria and sugar; a mixture of konjac gum and xanthan gum; a mixture of locust bean gum and xanthan gum; and a mixture of chitosan and pectin. The one or more other components are organic and selected from dispersants, binders, biocides, defoamers, thickeners, plasticizers, drying regulators, and mixtures thereof. 2) Applying the gellable liquid to the ceramic fibers of the fibrous support, 3) By lowering the temperature of the gellable liquid, the gellable liquid is gelled into a liquefiable gel form to obtain the prepreg. 4) Store the prepreg. The method comprising the step of

21. A method for producing a prepreg according to claim 20, wherein the thermoreversible hydrophilic colloid is selected such that the gelling temperature of the gellable liquid is greater than 20°C and less than 60°C.

22. A method for producing ceramic matrix components, 5) To convert a liquefiable gel into a gellable liquid, liquefy a liquefiable gel of a prepreg described in any one of claims 1 to 19 or a prepreg manufactured according to the method of claim 20 or 21. 6) Molding the prepreg to obtain a deformable preform, 7) Optionally, to gel the gellable liquid and obtain a cured preform. 8) Dry the preform obtained from step 6) or optionally from step 7) to obtain a ceramic matrix component. 9) Optionally, sinter the ceramic matrix component obtained from step 8). The method comprising the step of

23. A method for storing a prepreg as described in any one of claims 1 to 19 or a prepreg manufactured according to the method of claim 20 or 21, wherein the prepreg is stored in an airtight bag for more than one month.

24. A method for storing a prepreg according to claim 23, wherein the prepreg is stored for more than six months.

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