Abstract: A part is made of a composite material having an alumina matrix by impregnating a fiber texture with a fluid composition containing a liquid precursor of alumina, a thermoplastic resin, and a suspension of alumina powder, and subsequently convening the precursor into alumina. Additional solid fillers may be added to the impregnation composition. The impregnated fiber texture is preferably made by draping and molding plies that are pre-impregnated with said composition.

Abstract: The process is particularly well suited to the manufacture of composite materials, where a fibrous reinforcement texture is to be impregnated by a densifying matrix, and comprises the steps of:preparing a slurry containing a solid charge in the form of finely divided particles dispersed in a carrier liquid, which preferably contains an organic compound,placing a substrate inside an enclosure,creating a vacuum inside the enclosure, andcausing the slurry to pass through the substrate by means of a pressure difference.Uniformity of charge integration is ensured by forcing the slurry to pass through the substrate several times, in successively opposite directions. The concentration of solid charge in the slurry can be determined as a function of an intended charge percentage by volume in said substrate.

Abstract: A microwave antenna capable of operating at high temperature comprises at least one waveguide opening to the outside through an opening in a covering panel and including a tubular portion integrally formed with the panel, projecting inwards therefrom, and connected to the remainder of the panel around the opening, the panel and the integrated waveguide being made of a refractory composite material capable of ensuring microwave propagation and constituting a structural element capable of being raised to high temperature. The waveguide is filled with a refractory dielectric material such as an alumina-alumina type composite material.

Abstract: A laminated tubular fibrous structure is produced using a tubular braid and folding over its wall in order to form corrugations or wrinkles superposed in axial direction. The tubular braid is brought over a mandrel of which the inner diameter corresponds to that of the structure to be produced, by causing the braid to pass around a forming head which is mounted on the mandrel and of which the outer diameter corresponds to that of the structure to be produced, and at least one yarn is wound following a helicoidal path on the braid, around the mandrel and at the front of the forming head, between said head and a counter-piece of which the faces in facing relationship have shapes corresponding to the shape of the wrinkles to be produced, the winding of the yarn being performed while the forming head is moving away from the counter-piece progressively with the formation of the wrinkles.