Abstract: A plurality of unidirectional sheets (30a, 30b, 30c) are superposed in different directions and they are bonded together. At least one of the unidirectional sheets is made by spreading a tow so as to obtain uniform thickness, width not less than 5 cm, and a weight of no more than 300 g/m2, cohesion being imparted to the sheet so as to enable it to be handled prior to being superposed with other sheets. Advantageously, the unidirectional sheets are made of carbon fibers and are obtained by spreading out large tows.

Abstract: A method of obtaining fiber textures of carbon from a cellulose precursor includes the steps of: spinning cellulose filaments (12) from a viscose solution or a cellulose solution; subjecting the cellulose filaments to washing in water (21); impregnating the washed and non-dried cellulose filaments with an aqueous emulsion (41) of at least one organosilicon additive; drying the impregnated cellulose filaments; and obtaining a fiber texture made up of impregnated and dried cellulose filaments prior to carbonization.

Abstract: A method of obtaining fiber textures of carbon from a cellulose precursor includes the steps of: spinning cellulose filaments (12) from a viscose solution or a cellulose solution; subjecting the cellulose filaments to washing in water (21); impregnating the washed and non-dried cellulose filaments with an aqueous emulsion (41) of at least one organosilicon additive; drying the impregnated cellulose filaments; and obtaining a fiber texture made up of impregnated and dried cellulose filaments prior to carbonization.

Abstract: A plurality of unidirectional sheets (30a, 30b, 30c) are superposed in different directions and they are bonded together. At least one of the unidirectional sheets is made by spreading a tow so as to obtain uniform thickness, width not less than 5 cm, and a weight of no more than 300 g/m2, cohesion being imparted to the sheet so as to enable it to be handled prior to being superposed with other sheets. Advantageously, the unidirectional sheets are made of carbon fibers and are obtained by spreading out large tows.

Abstract: Carbon nanotubes are incorporated in the fiber structure by growing them on the refractory fibers of the substrate so as to obtain a three-dimensional substrate made of refractory fibers and enriched in carbon nanotubes. The substrate is densified with a matrix to form a part of composite material such as a friction part of C/C composite material.

Abstract: The subject of the present invention is a method of obtaining fibrous carbon materials by carbonization of cellulosic fibrous materials carried out continuously or batchwise in the presence of at least one organosilicon compound. Characteristically, said organosilicon compound is chosen from the family of crosslinked, cyclic or branched oligomers and resins, which have a number-average molecular mass of between 500 and 10 000 and which consist of units of formula SiO4 (called Q4 units) and units of formula SiOxRy (OR?)z.

Abstract: The subject of the present invention is a method of obtaining fibrous carbon materials by carbonization of cellulosic fibrous materials carried out continuously or batchwise in the presence of at least one organosilicon compound. Characteristically, said organosilicon compound is chosen from the family of cyclic, linear or branched polyhydrosiloxanes which are substituted with methyl and/or phenyl groups and the number-average molecular mass of which is between 250 and 10 000, advantageously between 2 500 and 5 000.

Abstract: The invention relates to a porous structure, characterized in that it comprises a porous matrix (15) made of carbon fabric, said porous matrix being bounded on at least one of its faces (17, 21) by an impermeable layer (19, 23) made of an element chosen from carbon fibres, carbon nanotubes and glassy carbon, said impermeable layer being linked to the porous matrix via carbon-carbon bonds. The invention also relates to a process for manufacturing such porous structures. Application to the fields of fuel cells and heat exchangers.

Abstract: The carbonization of cellulose fiber fabric comprises an initial stage of heat treatment up to 250° C. to 350° C., with a relatively high mean temperature rise speed of 10° C./min to 60° C./min, an intermediate stage up to 350° C. to 500° C. with a lower mean temperature rise speed of 2° C./min to 10° C./min, and a final stage up to 500° C. to 750° C. with a mean temperature rise speed that is again raised to 5° C./min to 40° C./min.

Abstract: A plurality of unidirectional sheets (30a, 30b, 30c) are superposed in different directions and they are bonded together. At least one of the unidirectional sheets is made by spreading a tow so as to obtain uniform thickness, width not less than 5 cm, and a weight of no more than 300 g/m2, cohesion being imparted to the sheet so as to enable it to be handled prior to being superposed with other sheets. Advantageously, the unidirectional sheets are made of carbon fibers and are obtained by spreading out large tows.

Abstract: Carbon nanotubes are incorporated in the fiber structure by growing them on the refractory fibers of the substrate so as to obtain a three-dimensional substrate made of refractory fibers and enriched in carbon nanotubes. The substrate is densified with a matrix to form a part of composite material such as a friction part of C/C composite material.

Abstract: A plurality of unidirectional sheets (30a, 30b, 30c) are superposed in different directions and they are bonded together. At least one of the unidirectional sheets is made by spreading a tow so as to obtain uniform thickness, width not less than 5 cm, and a weight of no more than 300 g/m2, cohesion being imparted to the sheet so as to enable it to be handled prior to being superposed with other sheets. Advantageously, the unidirectional sheets are made of carbon fibers and are obtained by spreading out large tows.

Abstract: Method and machine for producing multiaxial fibrous webs. A plurality of unidirectional sheets (30a, 30b, 30c) are superposed in different directions and they are bonded together. At least one of the unidirectional sheets is made by spreading a tow so as to obtain uniform thickness, width not less than 5 cm, and a weight of no more than 300 g/m2, cohesion being imparted to the sheet so as to enable it to be handled prior to being superposed with other sheets. Advantageously, the unidirectional sheets are made of carbon fibers and are obtained by spreading out large tows.

Abstract: A plurality of unidirectional sheets (30a, 30b, 30c) are superposed in different directions and they are bonded together. At least one of the unidirectional sheets is made by spreading a tow so as to obtain uniform thickness, width not less than 5 cm, and a weight of no more than 300 g/m2, cohesion being imparted to the sheet so as to enable it to be handled prior to being superposed with other sheets. Advantageously, the unidirectional sheets are made of carbon fibers and are obtained by spreading out large tows.

Abstract: The subject of the present invention is a method of obtaining fibrous carbon materials by carbonization of cellulosic fibrous materials carried out continuously or batchwise in the presence of at least one organosilicon compound. Characteristically, said organosilicon compound is chosen from the family of cyclic, linear or branched polyhydrosiloxanes which are substituted with methyl and/or phenyl groups and the number-average molecular mass of which is between 250 and 10,000, advantageously between 2,500 and 5,000.

Abstract: The subject of the present invention is a method of obtaining fibrous carbon materials by carbonization of cellulosic fibrous materials carried out continuously or batchwise in the presence of at least one organosilicon compound. Characteristically, said organosilicon compound is chosen from the family of crosslinked, cyclic or branched oligomers and resins, which have a number-average molecular mass of between 500 and 10 000 and which consist of units of formula SiO4 (called Q4 units) and units of formula SiOxRy (OR′)z.

Abstract: To make an annular fiber structure, a strip-shaped fabric (50), is used which is made up of two superposed unidirectional sheets, with the directions of the sheets forming opposite angles relative to the longitudinal direction of the strip, the two sheets being bonded together so as to form deformable elementary meshes, the fabric being wound while being deformed so as to transform it into a flat helix, the elementary meshes deforming in such a manner that variation in mass per unit area between the inside and outside diameters of the turns remains small, and the flat turns are pressed against one another.

Abstract: A yarn is formed from discontinuous parallel fibers which are not twisted and which are held together by a covering yarn of sacrificial material wound around the fibers. The fibers comprise an intimate mixture of fibers of at least two different natures selected from carbon fibers or pre-oxidized polyacrylonitrile based carbon precursor fibers, or anisotropic or isotropic pitch based carbon precursor fibers, or phenolic or cellulosic based carbon precursor fibers, and ceramic fibers or ceramic precursor fibers. The mixture of fibers comprises, in its carbon state, at least 15% by weight of high strength fibers, having a tensile strength of at least 1500 MPa and a modulus of at least 150 MPa, and at least 15% by weight of fibers with a low Young's modulus of at most 100 GPa.

Abstract: A yarn is formed from discontinuous parallel fibers which are not twisted d which are held together by a covering yarn of sacrificial material wound around the fibers. The fibers comprise an intimate mixture of fibers of at least two different natures selected from carbon fibers or pre-oxidized polyacrylonitrile based carbon precursor fibers, or anisotropic or isotropic pitch based carbon precursor fibers, or phenolic or cellulosic based carbon precursor fibers, and ceramic fibers or ceramic precursor fibers. The mixture of fibers comprises, in its carbon state, at least 15% by weight of high strength fibers, having a tensile strength of at least 1500 MPa and a modulus of at least 150 MPa, and at least 15% by weight of fibers with a low Young's modulus of at most 100 GPa.

Abstract: Fiber preforms for use in the manufacture of composite material annular ps are made by winding superposed layers of a strip of cloth (10) of spiral or helical shape comprising substantially helical warp threads and substantially radial weft threads. The mass per unit area of the warp of the helical cloth increases between its inside diameter and its outside diameter, and the layers of the strip of cloth are needled so as to be bonded together by fibers pulled from the yarn of the cloth, the increase in mass per unit area of the warp at least approximately compensating, in terms of density per unit volume of the preform, the decrease in density of the weft between the inside diameter and the outside diameter.