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 method comprises forming at least one external coating on the surface of the product to be protected, the coating being constituted by a composition mainly containing a mixture of phosphates, of silica, and of alumina belonging to a P.sub.2 O.sub.5 --SiO.sub.2 --Al.sub.2 O.sub.3 system, and, after drying, implementing heat treatment at a temperature that is sufficient at least to transform the external coating into an insoluble cement capable of forming a self-sealing glass. The external coating is formed of a liquid suspension that is applied by spray-painting or by means of a brush, the suspension containing said mixture of phosphates, of silica, and of alumina. Prior to forming the external coating, the product may be impregnated to the core within the residual open pores of the composite material, using a liquid solution of phosphates, of sodium, and of potassium.

Abstract: In a process according to the invention, before a carbon/fiber ceramic matrix is densified, the carbon fiber reinforcement material is subjected to a thermal treatment in a non-oxidizing environment at a temperature greater than 1300.degree. C. and less than 2200.degree. C., to act on the bonding between the fibers and the matrix. If a preform of the carbon fiber reinforcement material is formed prior to densification by a matrix, then the thermal treatment may be performed on the preform, prior to densification by the matrix. If the matrix is densified by chemical vapor infiltration inside a furnace, then the thermal treatment may be performed inside the infiltration furnace prior to the densification. The thermal treatment achieves a significant improvement in the strength of the resulting composite material.

Abstract: A method of densifying a porous substrate by means of a matrix containing carbon, for obtaining an article made of a composite material, the method comprising the following steps:providing on one side of a substrate to be densified a slip containing submicron carbon powder;establishing a pressure difference to force the slip through the substrate;filtering the liquid that has passed through the substrate to retain the carbon powder inside the substrate; andwhen densification of the substrate by means of the carbon powder has terminated, drying the densified substrate and transforming a carbon precursor introduced into the substrate into carbon by carbonization, thereby binding the powder constituting the matrix.

Abstract: A composite material containing carbon is protected against oxidation by forming, on the composite material, an inner layer, an intermediate layer containing boron or a boron compound, and an outer layer of silicon carbide. The inner layer formed on the composite material before the intermediate layer is formed, is made of a refractory carbide that does not contain boron and that is at least 60 microns thick, said inner layer insulating the intermediate layer from the carbon contained in the composite material.

Abstract: A process is provided for obtaining an article which is made of a carbon-containing composite material and which is protected against oxidation. The composite material, which is obtained by densifying a porous fibrous texture with a matrix and which exhibits a residual internal porosity, is impregnated under a vacuum with an alkaline compound in a liquid solution. The article is dried and heat-treated at a temperature sufficient to cause the alkaline compound to line the surfaces of the internal pores, thereby constituting the residual porosity and forming a continuous auto-cicatrizing internal protective coating. An additional external protective layer comprised of a wear- and oxidation-resistant material may be applied.

Abstract: There is provided a process for the hydrogenolysis of raw humid peat by treating untreated peat as obtained from the bog with carbon monoxide at a temperature of from 350.degree. to 373.degree. C. and under a pressure up to 35 MPa and recovering bitumen-like compounds from the non-aqueous phase.

Abstract: There is provided a novel process for preparing a carbon supported metal catalyst which comprises impregnating a peat material selected from finely divided peat, ammoniated peat and humic materials derived from peat with an aqueous solution of a metallic salt, drying the impregnated peat and pyrolyzing same in an inert atmosphere to yield a carbon supported metal and/or metal oxide.