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US-12623972-B2 - Prepreg for ceramic matrix composite

US12623972B2US 12623972 B2US12623972 B2US 12623972B2US-12623972-B2

Abstract

A prepreg including a support with, for more than 90% of the weight thereof, of ceramic fibers, and a thermoreversible liquefiable gel covering, at least in part, at least one portion of the ceramic fibers. The liquefiable gel including: 20% to 60% of ceramic particles and 0% to 10% of metal particles, both as percentage by volume based on the volume of the liquefiable gel; 0.2% to 10% of a thermoreversible hydrocolloid and 0% to 7% of one or more other constituents, both as a percentage by weight on the basis of the total weight of the ceramic particles and metal particles; the balance to 100% being water. It being possible for the ceramic particles and the metal particles to be replaced, partially or completely, by precursors of ceramic particles and of metal particles, respectively, capable of forming, by heat treatment above 200° C., ceramic particles and metal particles, respectively.

Inventors

  • Jérôme Leloup
  • Franceline Marguerite Louise Villermaux
  • Christian His

Assignees

  • SAINT-GOBAIN CENTRE DE RECHERCHES ET D'ETUDES EUROPEEN

Dates

Publication Date
20260512
Application Date
20210126
Priority Date
20200127

Claims (20)

  1. 1 . A prepreg comprising a support comprising more than 90% by weight of ceramic fibers and a thermoreversible liquefiable gel covering, at least in part, at least a portion of said ceramic fibers, said liquefiable gel comprising: ceramic particles and/or precursors of ceramic particles able to form, by a heat treatment of said precursors, at a temperature of greater than 200° C., such said ceramic particles, the total amount of the ceramic particles in the liquefiable gel and of the ceramic particles formed by said heat treatment being from 20% to 60%, as percentage by volume based on the volume of the liquefiable gel; metallic particles and/or precursors of metallic particles able to form, by a heat treatment of said precursors, at a temperature of greater than 200° C., such said metallic particles, the total amount of the metallic particles in the liquefiable gel and of the metallic particles formed by said heat treatment being from 0% to 10%, as percentage by volume based on the volume of the liquefiable gel; 0.2% to 10% of a thermoreversible hydrocolloid, as percentage by mass based on the total mass of the ceramic particles and of the metallic particles; 0% to 7% of one or more other constituents, as percentage by mass based on the total mass of the ceramic particles and of the metallic particles; the remainder to 100% being water, the water content by volume in the liquefiable gel being greater than 40%; such as to become liquid on heating.
  2. 2 . The prepreg as claimed in claim 1 , in which: the total amount of the ceramic particles in the liquefiable gel and of the ceramic particles formed by said heat treatment is greater than 25% and less than 55%, as percentage by volume based on the volume of the liquefiable gel, and/or the thermoreversible hydrocolloid is present in an amount of greater than 0.4%, as percentage by mass based on the total mass of the ceramic particles and of the metallic particles.
  3. 3 . The prepreg as claimed in claim 1 , in which: the ceramic particles of the liquefiable gel and the ceramic particles formed by said heat treatment are chosen from particles comprising more than 90% by weight of oxide(s), particles comprising more than 90% by weight of nitride(s), particles comprising more than 90% by weight of carbide(s), particles comprising more than 90% by weight of boride(s), and mixtures of these particles; and/or the thermoreversible hydrocolloid of the liquefiable gel is chosen from a gelatin, agar, a mixture of carrageenan and of a compound providing sodium cations and/or potassium cations and/or calcium cations, a mixture of furcellaria and of a sugar, a mixture of konjac gum and of xanthan gum, in a mass ratio of greater than 0.8 and less than 1.2, a mixture of locust bean gum and of xanthan gum, in a mass ratio of greater than 0.67 and less than 1.5, and a mixture of chitosan and of pectin, having a mass ratio of the amount of pectin to the amount of pectin and of chitosan of greater than 0.2 and less than 0.8.
  4. 4 . The prepreg as claimed in claim 3 , in which: more than 90% by volume of the ceramic particles in a set of particles consisting of the ceramic particles of the liquefiable gel and of the ceramic particles formed by said heat treatment comprise more than 90% by weight of oxide(s); and/or the thermoreversible hydrocolloid of the liquefiable gel is chosen from a gelatin, a mixture of chitosan and of pectin, having a mass ratio of the amount of pectin to the amount of pectin and of chitosan of greater than 0.2 and less than 0.8.
  5. 5 . The prepreg as claimed in claim 4 , in which more than 95% by volume of the ceramic particles in said set of particles comprise more than 99% by weight of oxide(s), and exhibit a chemical analysis such that Al 2 O 3 +SiO 2 ≥95%, as percentage by mass based on the oxides.
  6. 6 . The prepreg as claimed in claim 1 , in which: more than 90% by number of the ceramic fibers of the support, optionally assembled in the form of yarns, have a length of greater than 10 mm and an equivalent diameter, measured at half-length, of greater than 2 μm and less than 50 μm; and/or the ceramic fibers of the support comprise more than 90% by weight of oxide(s) and/or of nitride(s) and/or of carbide(s) and/or of boride(s) and/or of carbon; and/or the support is a single yarn, a web of yarns, a braid of yarns, a knit of yarns or an entanglement of fibers, said yarn or more than 50% of the yarns or of the ceramic fibers, as percentage by number, is/are coated, for more than 50% of their outer surfaces, with liquefiable gel.
  7. 7 . The prepreg as claimed in claim 6 , in which the ceramic fibers of the support, optionally assembled in the form of yarns, comprise more than 95% by weight of oxide(s), and exhibit a chemical analysis such that Al 2 O 3 +SiO 2 ≥95%, as percentage by mass based on the oxides.
  8. 8 . The prepreg as claimed in claim 7 , in which the ceramic fibers of the support, optionally assembled in the form of yarns, are chosen from glass fibers, amorphous silica fibers, corundum fibers, mullite fibers, mullite-corundum fibers and mixtures thereof.
  9. 9 . The prepreg as claimed in claim 1 , in which the support consists of a plurality of superposed webs.
  10. 10 . The prepreg as claimed in claim 1 , in which, in the liquefiable gel, the total amount of the ceramic particles in the liquefiable gel and of the ceramic particles formed by said heat treatment is greater than 25% and less than 55%, as percentage by volume based on the volume of the liquefiable gel, the ceramic particles of the liquefiable gel and the ceramic particles formed by said heat treatment being chosen from particles comprising more than 90% by weight oxide(s), particles comprising more than 90% by weight of nitride(s), particles comprising more than 90% by weight of carbide(s), particles comprising more than 90% by weight of boride(s), and mixtures of these particles; the whole of said ceramic particles of the liquefiable gel and said ceramic particles formed by said heat treatment exhibiting, by volume, a median size D 50 of less than 5 μm and greater than 0.1 μm, and a 99 percentile, D 99 , of less than 50 μm; and the thermoreversible hydrocolloid is present in an amount of greater than 0.4% and less than 9%, as percentage by mass based on the mass of the ceramic particles, said thermoreversible hydrocolloid being chosen from a gelatin, agar, a mixture of carrageenan and of a compound providing sodium cations and/or potassium cations and/or calcium cations, a mixture of furcellaria and of a sugar, a mixture of konjac gum and of xanthan gum, in a mass ratio of greater than 0.8 and less than 1.2, a mixture of locust bean gum and of xanthan gum, in a mass ratio of greater than 0.67 and less than 1.5, a mixture of chitosan and of pectin, having a mass ratio of the amount of pectin to the amount of pectin and of chitosan of greater than 0.2 and less than 0.8; and the other constituents are organic and present in an amount of greater than 0.1% and less than 6%, as percentage by mass based on the mass of the ceramic particles, said other constituents being chosen from dispersants, binders, biocidal agents, antifoam agents, thickeners, plasticizers, drying regulators and mixtures thereof; in the support, more than 90% by number of the ceramic fibers of the support, optionally assembled in the form of yarns, have a length of greater than 10 mm and an equivalent diameter, measured at half-length, of greater than 2 μm and less than 50 μm; and the ceramic fibers, optionally assembled in the form of yarns, represent more than 90% of the mass of the support, said ceramic fibers, optionally assembled in the form of yarns, comprising more than 90% by weight of oxide(s) and/or of nitride(s) and/or of carbide(s) and/or of boride(s) and/or of carbon; the support being a single yarn, a web of yarns, a braid of yarns, a knit of yarns or an entanglement of fibers, said single yarn or more than 50% of the yarns or of the fibers, as percentage by number, being coated, for more than 50% of their outer surfaces, with liquefiable gel.
  11. 11 . The prepreg as claimed in claim 1 , in which, in the liquefiable gel, the total amount of the ceramic particles in the liquefiable gel and of the ceramic particles formed by said heat treatment is greater than 25% and less than 55%, as percentage by volume based on the volume of the liquefiable gel, the ceramic particles of the liquefiable gel and the ceramic particles formed by said heat treatment being chosen from particles comprising more than 90% by weight of oxide(s), particles comprising more than 90% by weight consisting of nitride(s), particles comprising more than 90% by weight consisting of carbide(s), particles comprising more than 90% by weight consisting of boride(s), and mixtures of these particles; and the total amount of the metallic particles in the liquefiable gel and of the metallic particles formed by said heat treatment is greater than 0.5% and less than 9%, as percentage by volume based on the volume of the liquefiable gel, the whole of said ceramic particles of the liquefiable gel, of said ceramic particles formed by said heat treatment, of said metallic particles of the liquefiable gel, and of said metallic particles formed by said heat treatment exhibiting, by volume, a median size D 50 of less than 5 μm and greater than 0.1 μm, and a 99 percentile, D 99 , of less than 50 μm; the thermoreversible hydrocolloid is present in an amount of greater than 0.4% and less than 9%, as percentage by mass based on the sum of the mass of said ceramic particles of the liquefiable gel, of said ceramic particles formed by said heat treatment, of said metallic particles of the liquefiable gel, and of said metallic particles formed by said heat treatment; and being chosen from a gelatin, agar, a mixture of carrageenan and of a compound providing sodium cations and/or potassium cations and/or calcium cations, a mixture of furcellaria and of a sugar, a mixture of konjac gum and of xanthan gum, in a mass ratio of greater than 0.8 and less than 1.2, a mixture of locust bean gum and of xanthan gum, in a mass ratio of greater than 0.67 and less than 1.5, a mixture of chitosan and of pectin, having a mass ratio of the amount of pectin to the amount of pectin and of chitosan of greater than 0.2 and less than 0.8; and the other constituents are organic and present in an amount of greater than 0.1% and less than 6%, as percentage by mass based on the sum of the mass of said ceramic particles of the liquefiable gel, of said ceramic particles formed by said heat treatment, of said metallic particles of the liquefiable gel, and of said metallic particles formed by said heat treatment, said other constituents being chosen from dispersants, binders, biocidal agents, antifoam agents, thickeners, plasticizers, drying regulators and mixtures thereof; and in the support, more than 90% by number of the ceramic fibers of the support, optionally assembled in the form of yarns, have a length of greater than 10 mm and an equivalent diameter, measured at half-length, of greater than 2 μm and less than 50 μm; and the ceramic fibers, optionally assembled in the form of yarns, represent more than 90% of the mass of the support, said ceramic fibers, optionally assembled in the form of yarns, comprising more than 90% by weight of oxide(s) and/or of nitride(s) and/or of carbide(s) and/or of boride(s) and/or of carbon; the support being a single yarn, a web of yarns, a braid of yarns, a knit of yarns or an entanglement of fibers, said single yarn or more than 50% of the yarns or of the fibers, as percentage by number, being coated, for more than 50% of their outer surfaces, with liquefiable gel.
  12. 12 . The prepreg as claimed in claim 1 , in which: the thermoreversible hydrocolloid is present in an amount of less than 7%, as percentage by mass based on the total mass of said ceramic particles of the liquefiable gel, of said ceramic particles formed by said heat treatment, of said metallic particles of the liquefiable gel, and of said metallic particles formed by said heat treatment.
  13. 13 . The prepreg as claimed in claim 1 , in which, in the liquefiable gel, the total amount of the ceramic particles in the liquefiable gel and of the ceramic particles formed by said heat treatment is greater than 30% and less than 50%, as percentage by volume based on the volume of the liquefiable gel, more than 95% by volume of the set of particles comprising said ceramic particles of the liquefiable gel and of said ceramic particles formed by said heat treatment comprising more than 99% by weight of oxide(s), and exhibiting a chemical analysis such that Al 2 O 3 +SiO 2 ≥95%, as percentage by mass based on the oxides; and the whole of the said ceramic particles of the liquefiable gel and of said ceramic particles formed by said heat treatment exhibiting, by volume, a median size D 50 of less than 5 μm and greater than 0.1 μm, and a 99 percentile, D 99 , of less than 50 μm; and the thermoreversible hydrocolloid is present in an amount of greater than 0.5% and less than 4%, as percentage by mass based on the mass of the ceramic particles, said thermoreversible hydrocolloid being a gelatin; and the other constituents are organic and present in an amount of greater than 0.1% and less than 6%, as percentage by mass based on the mass of the ceramic particles, said other organic constituents being chosen from dispersants, binders, biocidal agents, antifoam agents, thickeners, plasticizers, drying regulators and mixtures thereof; and in the support, more than 90% by number of the ceramic fibers of the support, optionally assembled in the form of yarns, have a length of greater than 10 mm and an equivalent diameter, measured at half-length, of greater than 2 μm and less than 30 μm; and the ceramic fibers, optionally assembled in the form of yarns, represent more than 90% of the mass of the support, and said ceramic fibers, optionally assembled in the form of yarns, comprising more than 95% by weight of oxide(s) and exhibiting a chemical analysis such that Al 2 O 3 +SiO 2 ≥95%, as percentage by mass based on the oxides; the support being a single yarn, a web of yarns, a braid of yarns, a knit of yarns or an entanglement of fibers, said yarn or more than 50% of the yarns or of the fibers, as percentage by number, being coated, for more than 50% of their outer surfaces, with liquefiable gel.
  14. 14 . The prepreg as claimed in claim 1 , in which: the total amount of the metallic particles in the liquefiable gel and of the metallic particles formed by said heat treatment is greater than 0.5% and less than 9%, as percentage by volume based on the volume of the liquefiable gel; and/or one or more other constituents are present in an amount of greater than 0.5% and less than 6%, as percentage by mass based on the total mass of said ceramic particles of the liquefiable gel, of said ceramic particles formed by said heat treatment, of said metallic particles of the liquefiable gel, and of said metallic particles formed by said heat treatment.
  15. 15 . The prepreg as claimed in claim 14 , in which the thermoreversible hydrocolloid is in an amount of greater than 0.5% and less than 4%, as percentage by mass based on the total mass of said ceramic particles of the liquefiable gel, of said ceramic particles formed by said heat treatment, of said metallic particles of the liquefiable gel, and of said metallic particles formed by said heat treatment and/or the other constituent(s) is/are organic and chosen from dispersants, binders, biocidal agents, antifoam agents, thickeners, plasticizers, drying regulators and mixtures thereof.
  16. 16 . The prepreg as claimed in claim 1 , in which the ratio of the amount by mass of said other constituents to the amount by mass of thermoreversible hydrocolloid is less than 1, the amounts of thermoreversible hydrocolloid and of the “other constituents” being expressed as percentage by mass based on the total mass of said ceramic particles of the liquefiable gel, of said ceramic particles formed by said heat treatment, of said metallic particles of the liquefiable gel, and of said metallic particles formed by said heat treatment.
  17. 17 . The prepreg as claimed in claim 16 , in which said ratio is less than 0.6.
  18. 18 . A kit comprising a prepreg as claimed in claim 1 , and a hermetic bag, said prepreg being packed in said hermetic bag.
  19. 19 . A method for manufacturing a prepreg according to claim 1 , said method comprising the following steps: 1) preparing a gellable liquid having the following composition: 20% to 60% of ceramic particles, as percentage by volume based on the volume of the gellable liquid; 0% to 10% of metallic particles, as percentage by volume based on the volume of the gellable liquid; 0.2% to 10% of a thermoreversible hydrocolloid, as percentage by mass based on the total mass of the ceramic particles and of the metallic particles; 0% to 7% of one or more other constituents, as percentage by mass based on the total mass of the ceramic particles and of the metallic particles; the remainder to 100% being water; 2) applying said gellable liquid to ceramic fibers of a fibrous support; 3) gelling said gellable liquid in the form of a liquefiable gel by reducing the temperature of said gellable liquid, so as to obtain the prepreg; 4) storing the prepreg.
  20. 20 . The method for manufacturing a prepreg as claimed in claim 19 , in which the thermoreversible hydrocolloid is chosen so that the gelling temperature of the gellable liquid is greater than 20° C. and less than 60° C.

Description

TECHNICAL FIELD The invention relates to a prepreg intended in particular for the manufacture of a ceramic matrix component, in particular a ceramic matrix composite, or CMC. The invention also relates to a method for manufacturing such a prepreg and to a method for manufacturing a ceramic matrix component, in particular a CMC, from said prepreg. PRIOR ART A ceramic matrix component is a product essentially composed of ceramic fibers bonded together by a ceramic matrix. When it is sintered, it is known as “CMC”. A CMC exhibits high mechanical properties even at high temperatures. A ceramic matrix component may be manufactured by superposing prepregs each consisting of a fabric impregnated with a slurry of ceramic particles. The prepregs are flexible so as to be able to assume the desired shape. They may then be dried and preferably sintered to form a CMC. However, a ceramic matrix component, and in particular a CMC, manufactured from prepregs that have been stored for a long period or under poor conditions, exhibits degraded mechanical properties. There is therefore a continuing need for a prepreg exhibiting a better storability. The present invention is targeted at meeting this need, at least partially. DISCLOSURE OF THE INVENTION Summary of the Invention According to the invention, this aim is achieved by means of a prepreg comprising a support consisting, for more than 90%, more than 95% and preferably 100%, of its mass, of ceramic fibers, and a thermoreversible liquefiable gel covering, at least in part, at least a portion of said ceramic fibers, said liquefiable gel consisting of: 20% to 60% of ceramic particles, as percentage by volume based on the volume of the liquefiable gel;0% to 10% of metallic particles, as percentage by volume based on the volume of the liquefiable gel;0.2% to 10% of a thermoreversible hydrocolloid, as percentage by mass based on the total mass of the ceramic particles and of the metallic particles;0% to 7% of one or more other, preferably organic, constituents, as percentage by mass based on the total mass of the ceramic particles and of the metallic particles;the remainder to 100% being water, it being possible for the ceramic particles and the metallic particles to be partially or entirely replaced by precursors, in the form of particles or otherwise, of ceramic particles and of metallic particles, respectively, that are able to form, by heat treatment at a temperature of preferably greater than 200° C., preferably greater than 300° C., preferably greater than 400° C., ceramic particles and metallic particles, respectively. As will be seen in more detail in the remainder of the description, the inventors have discovered that such a prepreg retains its properties, in particular its deformability and bonding properties, even after a long period of storage. Without being bound by this theory, the inventors believe that the liquefiable gel limits the flow between the ceramic fibers of the support and/or on the support, and hence the migration of the ceramic and metallic particles. In addition, the water remains, at least partially, trapped within the gel, which limits evaporation and makes it possible to retain a composition which is substantially constant over time. The prepreg therefore advantageously remains homogeneous. Moreover, the composition of the liquefiable gel allows it to become liquid again by simple heating, and hence to become readily deformable again. However, the inventors have discovered that the specificity of this composition is not detrimental to the qualities of the ceramic matrix component, in particular of the CMC obtained. This transformation of the liquefiable gel is thermoreversible, the liquid obtained being a liquid which is gellable simply by cooling. The prepreg thus remains well suited to the manufacture of a ceramic matrix component, in particular of a CMC. Lastly, the retention of the water limits, or even eliminates, the need to add water during the manufacture of the ceramic matrix component. The method for manufacturing the ceramic matrix component is advantageously simplified as a result. A prepreg according to the invention may also comprise one or more of the following optional and preferred features: the liquefiable gel comprises:ceramic particles, in an amount of greater than 25% and less than 55%, as percentage by volume based on the volume of the liquefiable gel; and/ormetallic particles, in an amount of greater than 0.5% and less than 9%, as percentage by volume based on the volume of the liquefiable gel; and/ora thermoreversible hydrocolloid, in an amount of greater than 0.4% and less than 7%, as percentage by mass based on the total mass of the ceramic particles and of the metallic particles; and/orone or more other, preferably organic, constituents, in an amount of greater than 0.5% and less than 6%, as percentage by mass based on the total mass of the ceramic particles and of the metallic particles;the thermoreversible hydrocoll