Abstract: A method for detachably gluing at least one porous substrate to another material using at least one layer of a detachable adhesive comprising an ungluing admixture adapted for generating gases which, by gas expansion or gas migration towards at least one of the interfaces of the detachable adhesive layer, weakens the adhesive bond when heated by a detaching control, the aforementioned method including, before gluing, applying a metal sealing coating onto at least one of the substrates.

Abstract: A reinforcing fiber of the non-oxide ceramic type or of carbon to be used in the manufacture of a composite material with a glass, glass-ceramic or ceramic matrix, which composite exhibits good oxidative stability, is treated using a process comprising the steps consisting of: if necessary, oxidizing the fiber superficially or depositing thereon a layer of the same composition but including oxygen; placing the fiber in a chemical vapor deposition vessel; carrying out a pre-treatment at a temperature of 850.degree. to 1250.degree. C., in the presence of hydrogen, at a pressure of 50 to 300 mbar; injecting a mixture of neutral carrier gas and ammonia; stopping the injection and adjusting the pressure to a value of 1 to 10 mbar; injecting AlCl.sub.3 in a neutral diluting gas; producing on the fiber a deposit of AlN by simultaneously injecting a mixture of AlCl.sub.3 and a neutral carrier gas, and a mixture of NH.sub.

Abstract: Apparatus is provide for the fabrication of fiber composites composed of a fiber-reinforced vitreous or glass-ceramic matrix by winding fibers preimpregnated with constituents of the matrix onto a mandrel. The apparatus includes a furnace into which a winding mandrel can be introduced; elements for driving the mandrel in rotation around its axis inside the furnace; transit elements including a slot parallel to the axis of the mandrel positioned in the wall of the furnace for delivering fibers into the furnace; elements including a head for delivering fibers from supply spools positioned outside the furnace to the mandrel inside the furnace via the transit elements; and elements for actuating and controlling delivery of fibers and driving in rotation of the mandrel comprising elements for actuating and controlling the elements for driving the mandrel and the head for delivering the fibers as a function of winding parameters.

Abstract: In the process according to the invention, a gel is prepared by hydrolysis and polycondensation of precursor compounds which comprise at least silicon alcoholate and aluminum alcoholate and inorganic compounds of lithium and/or magnesium, the solvent is removed, and the gel obtained is subjected to a heat treatment resulting in dehydration and oxidation, then to compacting and ceramisization.The composition obtained is substantially in the form of solid ceramic solutions, such as .beta.-spodumene, cordierite and mullite.