Abstract: An interposition layer (12) is formed on the outside surface of a part (10) made of thermostructural composite material containing carbon, and a metal case is formed by casting molten metal (22) around the part provided with its interposition layer. The interposition layer has closed porosity and it is proof against the metal of the case, such that shrinkage of the metal during cooling is absorbed by compacting or collapsing the porosity of the interposition layer, thereby preserving the integrity of the metal case, and the interposition layer constitutes a diffusion barrier preventing eutetics forming by contact between the metal of the case and the composite material.

Abstract: Prior to applying an impregnation composition constituted by a solution of at least one phosphate, a part made of composite material is treated in depth by means of an aqueous solution that penetrates into the open internal pores of the composite material, and is then dried. The aqueous solution contains an additive which, after drying, imparts to the composite material, increased wettability by the impregnation composition. The additive contained in the aqueous solution is preferably constituted by at least one wetting agent that is soluble in water and non-ionic, such as an oxyethylenated fatty acid, an oxyethylenated fatty alcohol, an oxyethylenated alkyl-phenol or an ester of a high polyol.

Abstract: A material is impregnated with an aqueous solution containing precursors of a glass-containing phosphate base modified at least by the presence of zinc oxide, then dried and heat treated to form an internal oxidation protection constituted by the modified phosphate glass-containing base. The precursors are introduced into the aqueous solution so as to form a glass-containing base in which the molar ratio between the glass modifying oxides, comprising zinc oxide, and the glass forming oxides, principally comprising or consisting of phosphoric anhydride, is sufficiently high, in particular at least 0.6, preferably 0.9, to confer a resistance to corrosion by moisture on the glass-containing phosphate base.

Abstract: Each friction face of a brake disk (10) is masked (plates 40, 46) to isolate and seal the exterior from liquids, and the disk is immersed in a bath (30) of impregnating composition containing at least one substance which can form a protective layer against oxidation. Impregnation is effected by establishing a pressure difference between the pressure at the exterior of the exposed surfaces of the immersed brake disk (10) and the pressure inside the internal open pore space of the brake disk, without completely evacuating the latter, to force the impregnating composition to penetrate into the internal open pore space of the disk to a certain depth from the exposed surfaces, to form an internal oxidation protection. The pressure difference is adjusted depending on the desired depth of penetration of the impregnating composition into the internal open pore space.

Abstract: The method comprises forming a coating on the product of composite material to be protected. The coating contains a mixture of a non-oxide refractory ceramic in finely-divided form, at least one refractory oxide in finely-divided form and providing healing properties by forming a glass, and a binder constituted by a polymer that is a precursor of a non-oxide refractory ceramic. The polymer is transformed into a ceramic to obtain a protective layer comprising a non-oxide refractory ceramic phase and a healing phase which together constitute two interpenetrating lattices. After the ceramic precursor polymer has been transformed, a final heat treatment step may be performed at a temperature higher than the softening or melting temperature of the healing phase.

Abstract: A ceramic material based on Sialon, in particular on .beta.'-Sialon is obtained by reducing an aluminosilicate precursor by means of a gas phase comprising a mixture of hydrogen and nitrogen doped with a gaseous carbon compound. The gaseous carbon compound is a gas containing carbon in combined form, e.g. an alkane, and its concentration by volume in the gas is less than 3%. The method is particularly suitable for forming Sialon-based coatings on substrates that are solid or fibrous. For composite materials constituted by a fiber preform densified by means of a matrix, the method can be used to form an interphase coating on the fibers of the preform prior to densifying the preform, or the method can be used to form a matrix that is based on Sialon.

Abstract: Anti-oxidation protection for a silicon compound under both an active oxidation condition and a passive oxidation condition is achieved by forming an intermediate layer devoid of the element silicon between the surface of the silicon compound ceramic, such as SiC, and a silica based vitreous outer layer, such as SiO.sub.2, to be subsequently deposited. The intermediate layer is made of alumina (Al.sub.2 O.sub.3) or an alumina precursor, so as to constitute a reaction barrier between the silicon compound and the silica outer layer on the one hand, and trap any amount of silica that may be formed by an oxidation of the silicon compound.

Abstract: A porous substrate is placed inside an enclosure and a gas flow is injected into the enclosure under predetermined conditions of temperature and pressure to form a solid deposit within the accessible pores inside the substrate. A wall that is permeable to the gas flow is interposed on the path of the flow between its inlet into the enclosure and the substrate, the wall not being in contact with the substrate, thereby forming around the substrate a region which is free from strong turbulence so that infiltration is performed essentially under diffusion conditions, thereby minimizing the deposition gradient within the volume of the substrate.

Abstract: A layer (16) forming interphase in a material having a lamellar structure is situated between the fibers of the texture and the matrix, and at least one layer (14) forming control interphase is situated between the surface of the fibers (10) and the lamellar interphase (16) in such a way as to define, for those cracks which have spread through the matrix (18) and the lamellar interphase (16), a preferential propagation zone away from direct contact with the actual fibers (10).

Abstract: In order to obtain a reinforcement texture made essentially of silicon compound based ceramic fibers in the production of a composite material, the fibers are spun from a ceramic presursor in the molten state, after which they are submitted to a partial cross-linking in view of making the fibers infusible. The cross-linking of the fibers in the precursor in the infusible state is continued and, while they are maintained in the organic state, the cross-linked fibers are submitted to one or several textile-forming operations, such as weaving, layering, needling . . . in order to arrive at the multidirectional texture. Then, the texture is submitted to a heat treatment by pyrolysis to induce the ceramic state of the fibers and so obtain the required texture, which is essentially made of ceramic fibers having a silicon compound base, in particular silicon carbide.

Abstract: In order to obtain a reinforcement texture made essentially of silicon compound based ceramic fibers in the production of a composite material, the fibers are spun from a ceramic precursor in the molten state, after which they are submitted to a partial cross-linking in view of making the fibers infusible. The cross-linking of the fibers in the precursor in the infusible state is continued and, while they are maintained in the organic state, the cross-linked fibers are submitted to one or several textile-forming operations, such as weaving, layering, needling . . . in order to arrive at the multidirectional texture. Then, the texture is submitted to a heat treatment by pyrolysis to induce the ceramic state of the fibers and so obtain the required texture, which is essentially made of ceramic fibers having a silicon compound base, in particular silicon carbide.

Abstract: A composite structure having a fibrous reinforcing body formed from fibers of a refractory material, a ceramic matrix surrounding the fibers of the reinforcing body and an intermediate layer of a refractory material having a laminar structure disposed between the fibers of the refractory material having a laminar structure disposed between the fibers of the refractory material and the ceramic matrix and adherent to both. The intermediate layer has a thickness sufficient to reduce the susceptibility of the structure to crack propagation and to increase impact strength but not exceeding 3.0 microns. The intermediate layer is also elastically deformable in shear and has an elongation at break greater than the matrix.

Abstract: A thin, refractory, intermediate adhesive layer of laminar structure is deposited in oriented fashion on the reinforcing fibers by chemical vapor deposition, this intermediate layer having a greater elongation at break than the matrix and having a thickness of between 0.2 and 3 micrometers; the material forming the intermediate layer can be laminar pyrocarbon or boron nitride; the ceramic matrix is then infiltered, preferably by chemical vapor deposition, inside the pores of the reinforcement.

Abstract: The present invention relates to a composite material, of the type comprising a matrix in resin coke carbon and a refractory fibrous reinforcement, wherein the elementary fibers composing the fibrous reinforcement are coated before use with a layer of pyrolytic carbon the thickness of which layer can vary between 0.01 .mu.m and 1.0 .mu.m.The invention further relates to a method for preparing said material.

Abstract: The present invention relates to a process for making bioactive coatings on osseous prostheses, wherein a mist of particles containing calcium ions and orthophosphate ions is made from solutions and said mist is brought into contact with a substrate (notably an implant) made of inert material under such operational conditions that a hydroxyapatite coating is formed by reaction on the hot surface of said inert substrate, said process being characterized by the fact that the operating conditions to make the deposit are selected so that a liquid film forms on the hot surface of said substrate during the deposition.