Classifications

• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/71—Ceramic products containing macroscopic reinforcing agents
  • C04B35/78—Ceramic products containing macroscopic reinforcing agents containing non-metallic materials
  • C04B35/80—Fibres, filaments, whiskers, platelets, or the like
• • C—CHEMISTRY; METALLURGY
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  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/515—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics
  • C04B35/56—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on carbides or oxycarbides
  • C04B35/565—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on carbides or oxycarbides based on silicon carbide
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/62227—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products obtaining fibres
  • C04B35/62272—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products obtaining fibres based on non-oxide ceramics
  • C04B35/62277—Fibres based on carbides
  • C04B35/62281—Fibres based on carbides based on silicon carbide
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/626—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B
  • C04B35/628—Coating the powders or the macroscopic reinforcing agents
  • C04B35/62844—Coating fibres
  • C04B35/62857—Coating fibres with non-oxide ceramics
  • C04B35/62873—Carbon
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/626—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B
  • C04B35/628—Coating the powders or the macroscopic reinforcing agents
  • C04B35/62884—Coating the powders or the macroscopic reinforcing agents by gas phase techniques
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
  • C04B41/53—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone involving the removal of at least part of the materials of the treated article, e.g. etching, drying of hardened concrete
  • C04B41/5338—Etching
  • C04B41/5353—Wet etching, e.g. with etchants dissolved in organic solvents
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
  • C23C16/02—Pretreatment of the material to be coated
  • C23C16/0227—Pretreatment of the material to be coated by cleaning or etching
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
  • C23C16/22—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the deposition of inorganic material, other than metallic material
  • C23C16/26—Deposition of carbon only
• • D—TEXTILES; PAPER
  • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
  • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
  • D04H13/00—Other non-woven fabrics
  • D04H13/001—Making non-woven fabrics from staple fibres, filaments or yarns, bonded to at least one web-like material, e.g. woven, knitted non-woven fabric, paper, leather, during consolidation
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
  • D06M11/00—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising
  • D06M11/07—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising with halogens; with halogen acids or salts thereof; with oxides or oxyacids of halogens or salts thereof
  • D06M11/11—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising with halogens; with halogen acids or salts thereof; with oxides or oxyacids of halogens or salts thereof with halogen acids or salts thereof
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
  • D06M11/00—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising
  • D06M11/07—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising with halogens; with halogen acids or salts thereof; with oxides or oxyacids of halogens or salts thereof
  • D06M11/11—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising with halogens; with halogen acids or salts thereof; with oxides or oxyacids of halogens or salts thereof with halogen acids or salts thereof
  • D06M11/13—Ammonium halides or halides of elements of Groups 1 or 11 of the Periodic Table
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
  • D06M11/00—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising
  • D06M11/58—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising with nitrogen or compounds thereof, e.g. with nitrides
  • D06M11/64—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising with nitrogen or compounds thereof, e.g. with nitrides with nitrogen oxides; with oxyacids of nitrogen or their salts
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
  • D06M11/00—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising
  • D06M11/73—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising with carbon or compounds thereof
  • D06M11/74—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising with carbon or compounds thereof with carbon or graphite; with carbides; with graphitic acids or their salts
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
  • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
  • C04B2235/50—Constituents or additives of the starting mixture chosen for their shape or used because of their shape or their physical appearance
  • C04B2235/52—Constituents or additives characterised by their shapes
  • C04B2235/5208—Fibers
  • C04B2235/5216—Inorganic
  • C04B2235/524—Non-oxidic, e.g. borides, carbides, silicides or nitrides
  • C04B2235/5244—Silicon carbide
• • D—TEXTILES; PAPER
  • D10—INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
  • D10B—INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
  • D10B2101/00—Inorganic fibres
  • D10B2101/10—Inorganic fibres based on non-oxides other than metals
  • D10B2101/14—Carbides; Nitrides; Silicides; Borides
  • D10B2101/16—Silicon carbide
• • D—TEXTILES; PAPER
  • D10—INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
  • D10B—INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
  • D10B2401/00—Physical properties
  • D10B2401/10—Physical properties porous

Definitions

• the present invention relates to silicon carbide (SiC) fibers used as reinforcement in the manufacture of composite materials.
• the layer is only reduced to a thickness of the order of 0.005 microns, which corresponds to the limit of detection.
• Example 2 thus discloses a mixture of 250 ml of the aqueous HF solution with 250 ml of the HNO 3 solution.
• the acid solution of this example has a nitric acid content of between 4.76 and 5.54 mol / L and an HF content of approximately 11.5 mol / l, ie a molar ratio.
• hydrofluoric acid on nitric acid between 2.08 and 2.41.
• the acid concentrations described in this document are so strong that it is impossible to control the reaction.
• the inventors have thus surprisingly discovered that the combined use of hydrofluoric acid and nitric acid, in aqueous solution, without the addition of acetic acid, made it possible to completely remove the silica layer present on the surface of the carbide fibers.
• microporous carbon layer is a good bonding interface for depositing a pyrolytic carbon layer.
• the carbon does not present any particular structural organization. It is microporous and has very high specific surface areas (of the order of 1500 m 2 / g) associated with pores of very small sizes (pore diameter of about one nanometer).
• a pyrolytic carbon layer is deposited on this microporous carbon layer, the two layers form a mixed carbon interphase which makes it possible to increase the mechanical characteristics of the composite material, in particular with regard to the stress and the deformation at break. .
• the present invention therefore relates to a process for treating silicon carbide fibers comprising the step of chemical treatment of the fibers with an aqueous acid solution containing hydrofluoric acid and nitric acid in order to remove the silica present on the surface of the fibers and form a microporous carbon layer, characterized in that said aqueous solution of acid does not contain acetic acid.
• the inventors have discovered that the combined use of hydrofluoric acid and nitric acid in aqueous solution is more advantageous than the use of each of these acids alone and that their combined use with acetic acid since it allowed to totally eliminate the silica present on the surface of the fibers and to form a microporous carbon layer less than or equal to 100 nm.
• HF eliminates the silica present on the surface of the fibers and HNO3 renders the silica soluble and oxidizes the silicon carbide and oxycarbide of the fiber to allow the creation of the microporous carbon layer.
• this process is not implemented during the fiber manufacturing process or as a washing step of this process, that is to say on fibers having on their surface initial products which have not unreacted, such as for example silicon dioxide particles.
• the method according to the invention therefore does not serve as a simple step of washing the fibers, but allows the formation of a microporous carbon layer on the surface of the fibers.
• the acid ratio that can be used in the context of the present invention depends on the thickness of the desired microporous carbon layer, on the type of fibers to which the treatment is applied (carbide ratio on oxycarbides and carbide types) and on the temperature of the treatment.
• the aqueous acid solution according to the invention contains a molar ratio of hydrofluoric acid / nitric acid of less than 1.5, advantageously less than 1 , 2, still more preferably less than 1, even more preferably less than 0.8, in particular greater than 0.1, more preferably greater than 0.15, still more preferably greater than 0.2.
• the acidic solutions are not too concentrated to be able to manage controllable etching kinetics and therefore good reproducibility of the carbon layer formed.
• the aqueous acid solution according to the invention contains at 20 ° C a nitric acid content of between 0.5 and 5 mol / l, advantageously between 2 and 5 mol / l, in particular between 0.5 and 4 mol / l, especially between 2 and 4 mol / l.
• the aqueous acid solution according to the invention contains, at 20 ° C., a hydrofluoric acid content of between 0.5 and 4 mol / l, advantageously between 0.5 and 3 mol / l, in particular between 0 , 5 and 2.5 mol / l, more particularly between 0.5 and 2 mol / l.
• the amount of HF determines the kinetics of reaction for a given concentration of HN0 3 .
• the chemical treatment step is carried out at ambient temperature, that is to say between 20 and 25 ° C. It is therefore not implemented hot in contrast to what is recommended in the patent application FR2642158 when nitric acid is present.
• the duration of the chemical treatment step depends on the thickness of the microporous carbon layer that one wishes to obtain on the surface of the fiber and the ratio HF / HN0 3 used.
• this step lasts between 10 minutes and 5 hours, advantageously between 3 and 5 hours to obtain a layer less than or equal to 100 nm.
• the chemical treatment step is carried out hot, i.e. at a temperature above room temperature, particularly at about 30 ° C.
• the duration of the chemical treatment step may in this case be lower than at room temperature.
• this step lasts between 10 minutes and 3 hours, preferably between 10 minutes and 2 hours to obtain a layer less than or equal to 100 nm.
• the chemical treatment step is carried out cold, i.e. at a temperature below room temperature, particularly at about 10 ° C. In the case where the temperature of the chemical treatment is about 30 ° C, this step lasts between 2 hours and 8 hours, advantageously between 2 hours and 6 hours to obtain a layer less than or equal to 100 nm.
• the chemical treatment according to the present invention is carried out by dipping the fibers in an aqueous acid solution according to the present invention for the time necessary for the removal of the superficial silica layer and the formation of the microporous carbon.
• the acidic aqueous solution according to the invention contains only water and the HF and HNO3 acids.
• the process according to the present invention may comprise a step of rinsing with water and drying the treated fibers obtained. this allows to eliminate any residual trace of acid solution used in the process according to the present invention.
• the silicon carbide fibers obtained after the treatment according to the present invention have a surface layer of microporous carbon ⁇ 100 nm, advantageously about 50 nm. Even more advantageously, the superficial silica layer present on the untreated fibers has disappeared. Indeed, before treatment the fibers are covered with silica on a variable thickness, the average of which is approximately equal to 0.3 microns. Thanks to the treatment according to the present invention, this layer has completely disappeared.
• the fibers treated by the process according to the present invention may have any form, for example threads, tows, strands, cables, fabrics, felts, braids, mats and even two-dimensional or three-dimensional preforms. These are in particular Nicalon® fibers commercially available from the company NIPPON CARBON Co. It may also be Tyranno ® fibers from UBE Industries.
• the fibers to be treated are covered with a size which can not be removed by the chemical treatment, and the process according to the present invention comprises the preliminary step of almost complete elimination of said size, advantageously by treatment. thermal.
• the acidic aqueous solution according to the invention causes a partial dissolution of a size based on polyvinyl alcohol, it has no effect on the vinyl acetate sizing which can also cover some silicon carbide fibers.
• the subsequent treatment with the aqueous acid solution according to the invention can be completely effective, it is therefore preferable to eliminate beforehand the vinyl acetate sizing.
• the SiC fibers can be subjected to a thermal desensitization treatment (this technique being more effective than a chemical desizing, also usable).
• the SiC fibers are, for example, brought to a temperature of 600 ° C. in the air for 20 seconds. The use of a relatively moderate temperature for a very short period of time avoids a notable oxidation of the silicon carbide.
• the fibers to be treated by the process according to the present invention do not have on their surface residues initial products used in their manufacture, such as for example particles of silica dioxide.
• the method according to the invention comprises the additional step of depositing a pyrolytic carbon layer on the silicon carbide fibers treated by the process according to the present invention. This deposition can be carried out by techniques well known to those skilled in the art, for example as described in the patent application FR2,567,874. This deposit therefore takes place directly on the microporous carbon layer.
• the present invention further relates to a method of manufacturing a fibrous preform comprising forming a fibrous structure based on silicon carbide fibers, the fibers having been treated according to the treatment method according to the present invention.
• the shaping of the preform can be carried out by winding, weaving, stacking, and possibly needling of two-dimensional layers of fabric or plies of cables containing the silicon carbide fibers ...
• the fibers are treated before the formation of the fibrous structure.
• the fibers are used for producing a fiber preform of composite material parts.
• the fibers are treated after formation of the fibrous structure.
• it is the fibrous structure which is directly immersed in the bath containing the acidic aqueous solution according to the present invention.
• the present invention finally relates to a method of manufacturing a composite material part comprising the production of a fiber preform in accordance with the method according to the invention and the densification of said preform.
• the manufacture of composite material parts reinforced with silicon carbide fibers is well known. It generally comprises the production of a ceramic fiber preform having a shape close to that of the part to be manufactured and the densification of the preform by a matrix.
• the fiber preform is the reinforcement of the part whose role is essential vis-à-vis the mechanical properties.
• the densification of the fibrous reinforcement may be carried out by a liquid route (impregnation with a precursor resin of the matrix and transformation by crosslinking and pyrolysis, the process being repeatable) or by a gaseous route (chemical vapor infiltration of the matrix).
• the invention applies in particular to the production of parts made of at least partly ceramic, and advantageously totally ceramic matrix (CMC) composite material, formed by a fibrous reinforcement of silicon carbide fibers densified by at least one matrix.
• partly ceramic or totally ceramic in particular carbide, nitride, refractory oxides, etc.
• Typical examples of such silicon carbide fiber CMC materials are SiC-SiC materials (reinforcement of silicon carbide fibers and silicon carbide matrix).
• Figure 1 shows the atomic concentration of silicon, carbon, nitrogen and oxygen (in%) as a function of the depth (in nm) inside the fiber before treatment (zero corresponds to the surface of the fiber).
• FIG. 2 represents the atomic concentration of silicon, carbon, nitrogen and oxygen (in%) as a function of the thickness of the fiber after treatment according to the invention (zero corresponds to the surface of the fiber).
• the process according to the invention has been carried out on fibrous textures, and more particularly on SiC fiber fabrics produced by the Japanese company NIPPON CARBON Co. Ltd, using a silica elimination and formation treatment.
• a layer of microporous carbon by soaking the textures in a bath containing an aqueous solution of hydrofluoric acid (0.7 mol / l) and nitric acid (3 mol / l) for 4 hours at room temperature.
• the fibrous textures obtained are then rinsed with water and dried.
• the SiC fibers Prior to this treatment, desensitization of the fibrous textures is carried out thermally.
• the SiC fibers are brought to a temperature of 600 ° C in air for 20 seconds.
• the method according to the patent application FR2640258 has been implemented on fibrous textures, and more particularly SiC fiber formed fabrics produced by the Japanese company NIPPON CARBON Co. Ltd using a treatment of silica removal by soaking textures in a bath containing an aqueous solution of hydrofluoric acid (at a concentration of between about 20 and 30 mol%) for about 1 hour at room temperature.
• the fibrous textures obtained are then rinsed with water and dried.
• a desizing fibrous textures is carried out thermally, for example at 600 ° C in air for 20 seconds.
• the fibers before treatment are covered with silica to an average thickness of about 0.3 microns. After this treatment this thickness is reduced to about 0.005 microns and no trace of microporous carbon is present on the surface of the fibers.
• Example 2 The same procedure as in Example 1 is carried out except that the bath contains an aqueous solution of hydrofluoric acid at 2.3 mol / l and nitric acid at 4 mol / l, which the treatment time is 75 minutes and the treatment temperature is 30 ° C.
• the thickness of the microporous carbon layer obtained on the surface of the fibers is 215 nm.
• Example 2 The same procedure is used as in Example 1 except that the treatment time is 30 minutes and the treatment temperature is 30 ° C.
• the thickness of the microporous carbon layer obtained on the surface of the fibers is 30 nm.
• Example 2 The same procedure as in Example 1 is carried out except that the treatment time is 120 minutes and the treatment temperature is 30 ° C.
• the thickness of the microporous carbon layer obtained on the surface of the fibers is 100-90 nm.
• Example 2 The same procedure is used as in Example 1 except that the treatment time is 480 minutes and the treatment temperature is 10 ° C.
• the thickness of the microporous carbon layer obtained on the surface of the fibers is at most 70 nm.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Ceramic Engineering (AREA)
• Manufacturing & Machinery (AREA)
• Materials Engineering (AREA)
• Organic Chemistry (AREA)
• Structural Engineering (AREA)
• Inorganic Chemistry (AREA)
• Textile Engineering (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Mechanical Engineering (AREA)
• General Chemical & Material Sciences (AREA)
• Metallurgy (AREA)
• Nanotechnology (AREA)
• Chemical Or Physical Treatment Of Fibers (AREA)
• Carbon And Carbon Compounds (AREA)

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• 2012
  • 2012-04-13 FR FR1253426A patent/FR2989371B1/fr not_active Expired - Fee Related
• 2013
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  • 2013-04-11 IN IN9029DEN2014 patent/IN2014DN09029A/en unknown
  • 2013-04-11 CA CA2869916A patent/CA2869916A1/fr not_active Abandoned
  • 2013-04-11 RU RU2014144147A patent/RU2641045C2/ru active
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  • 2013-04-11 EP EP13720477.2A patent/EP2836473B1/fr active Active
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