Abstract: The invention relates to a process for producing a ceramic matrix composite (CMC) part by infiltration of a suspension (S) of a ceramic powder into a fibrous reinforcement (14). A suspension (S) of ceramic powder containing particles of chosen particle size, dispersed in at least one solvent, is prepared. The infiltration of the suspension is carried out in a single step in the fibrous reinforcement (14) positioned between a mold (12) and a permeable membrane (16), which makes it possible to apply a vacuum (V) and to subsequently remove the solvent from the suspension through the permeable membrane (16). The invention applies to the production of large-sized parts of complex shape, in particular in the field of aeronautics and aerospace engineering.

Abstract: The invention relates to a process for producing a ceramic matrix composite (CMC) part by infiltration of a suspension (S) of a ceramic powder into a fibrous reinforcement (14). A suspension (S) of ceramic powder containing particles of chosen particle size, dispersed in at least one solvent, is prepared. The infiltration of the suspension is carried out in a single step in the fibrous reinforcement (14) positioned between a mould (12) and a permeable membrane (16), which makes it possible to apply a vacuum (V) and to subsequently remove the solvent from the suspension through the permeable membrane (16). The invention applies to the production of large-sized parts of complex shape, in particular in the field of aeronautics and aerospace engineering.

Abstract: The present invention provides: fiber preforms sheathed in a boron nitride coating, said coating (generated on said previously-prepared fiber preforms) having a structure that is original: microporous and granular; thermostructural composite materials in which the reinforcing fabric is constituted by said fiber preforms; and methods of preparing said fiber preforms and said thermostructural composite materials, respectively. The composites of the invention have their fiber preforms, based on fibers (F), sheathed in an original interphase (IBN) and embedded in the densification matrix (M).

Abstract: The present method of manufacturing a ceramic composite material, composed of matrix and reinforcing materials and an intermediate weak interfice material, creates a composite material particuarly intended for use at temperatures above 1400° C. and in an oxidizing environment. The matrix and reinforcing materials consist of the same or different ceramic oxides having a melting point above 1600° C. The interface material provides in combination with the matrix and reinforcing materials a stress field liable to micro aciding. The reinforcing material is immersed into a powder slurry containing carbon (C) and ZrO2 so as to be coated thereby and then dried. After which, the thus created composite material is subjected to green forming and densifying steps. Finally, the composite material undergoes a heat-treatment in air leaving a porous structure of the interface material.

Abstract: Woven or nonwoven long fiber sheets filled with two precursors each constituting an intermediate stage in a process for the preparation of a vitreous ceramic composition by the sol-gel route by hydrolysis and polycondensation using alcoholates or analogous compounds as the starting materials, that is to say an interface precursor in the form of a gel rich in water and a matrix precursor in the form of discrete particles capable of sintering at relatively low temperature, are stacked; the fibrous structure is compressed in the direction of stacking and the whole is heat-treated in order to convert the two precursors into a continuous matrix.

Abstract: In the process according to the invention, a gel is prepared by hydrolysis and polycondensation of precursor compounds which comprise at least silicon alcoholate and aluminum alcoholate and inorganic compounds of lithium and/or magnesium, the solvent is removed, and the gel obtained is subjected to a heat treatment resulting in dehydration and oxidation, then to compacting and ceramisization.The composition obtained is substantially in the form of solid ceramic solutions, such as .beta.-spodumene, cordierite and mullite.

Abstract: The matrix is formed by particles of ceramic material which are introduced into the empty spaces of a fibrous structure and are bonded to one another by bridges of ceramic material obtained by in situ pyrolysis of a liquid polymer.By means of this process, a composite material of low porosity, despite a high reduction in volume during pyrolysis, is obtained relatively rapidly.

Abstract: Low viscosity, crosslinkable polysilanes that are liquid at ambient temperatures and essentially free of volatiles, well adapted for conversion into silicon carbide ceramics at elevated temperatures, are prepared by (a) reacting at least one silane monomer of the formula (1):R.sup.1 R.sup.2 SiCl.sub.2 (1)in which R.sup.1 is a hydrogen atom or a hydrocarbon radical and R.sup.2 is a vinyl radical, with at least one organic or organosilicon monochlorinated comonomer, in the presence of molten sodium in an organic solvent and wherein the ratio r.sub.1 of the number of moles of the silane monomer of formula (1) to the number of moles of the monochlorinated comonomer ranges from 0.