Abstract: The carbon-carbon composite material is obtained by densification with a pyrolytic carbon matrix originating from a precursor in gaseous state at least in a main external phase of the matrix, and, at the end of the densification, final heat treatment is performed at a temperature lying in the range 1400° C. to 1800° C.

Abstract: The carbon-carbon composite material is obtained by densification with a pyrolytic carbon matrix originating from a precursor in gaseous state at least in a main external phase of the matrix, and, at the end of the densification, final heat treatment is performed at a temperature lying in the range 1400° C. to 1800° C.

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: Preforms for producing annular parts of composite material are produced by inding a strip (1) of fibrous material around an elliptical mandrel (10) to produce an elliptical sleeve which can be cut obliquely, cutting taking place either before or after one or more densification steps. The cutting plane is inclined relative to the right cross section of the elliptical sleeve, and the inner and outer portions of the cut rings are machined to obtain circular elements. Such elements can produce annular parts of composite material having a reduced tendency to delanination under circumferential stress. The superposed layers are needling together during winding. A uniform needling density per unit area can be obtained by controlled displacement of the needle board (5) and of the elliptical mandrel (10) relative to each other as the mandrel turns, to compensate for the eccentricity of the cross section of the mandrel. These methods are particularly suitable for producing brake disk preforms.