Abstract: A gas diffusion electrode comprises a cloth (12) of activated carbon fibers having a first face coated in a hydrophobic material (14) and a second face on which particles of catalyst (16) are fixed directly and are dispersed in substantially uniform manner over the fibers. The electrode can be used in an electrochemical cell of a proton exchange membrane fuel-cell battery, or in an electrochemical reactor, e.g. for making chlorine and caustic soda.

Abstract: A carbon fiber fabric having large specific surface area is made using a rayon precursor, and a catalyst is fixed on the fabric by impregnation or by cationic exchange. The carbon fiber fabric has pores with a mean size lying in the range 0.3 nm to 3 nm, a carbon content greater than 99%, and a high density of functional groups per unit area which favors the dispersion of metal catalyst in the form of fine particles and which is good for highly selective catalytic reactions in fine chemistry.

Abstract: The carbon fibers present a mean lattice surface spacing (d002) not less than 0.36 nm, preferably 0.38 nm, at a crystallite size such that the mean height (Lc) lies in the range 0.7 nm to 0.3 nm and the mean width (La) lies in the range 2 nm to 6 nm, and it presents total porosity lying in the range 10% to 30%. The electrode is preferably a rayon-precursor carbon cloth and it constitutes the anode (10) of a secondary cell having a cathode (20) which includes lithium enabling lithium ions to be inserted and de-inserted, and an electrolyte (30).

Abstract: An alloy of zirconium and niobium that includes erbium as a consumable neutron poison, its method of preparation and a component comprising said alloy are provided. This invention relates to an alloy of zirconium and niobium that includes erbium as a consumable neutron poison. The invention also relates to a method for the preparation and conversion of said alloy and a component comprising said alloy. Such an alloy is particularly intended for the manufacture of cladding and/or other elements or structural components of fuel assemblies for nuclear reactors using water as coolant.

Abstract: A fabric made of fibers of a carbon-precursor cellulose material is impregnated with a composition containing at least one inorganic ingredient having a function of promoting dehydration of cellulose, and the fabric is subjected to heat treatment. This treatment consists in raising temperature at a speed lying in the range 1.degree. C./min to 15.degree. C./min followed by keeping the temperature constant in the range 350.degree. C. to 500.degree. C., and it is followed by a step of washing the fabric. This produces directly an activated fabric of carbon fibers having a specific surface area of not less than 600 m.sup.2 /g, without subsequent activation treatment at a higher temperature.

Abstract: An activation furnace for activating a fiber sleet having carbonized yarn filaments includes a horizontal activation enclosure containing a heater, an inlet section and an outlet section through which the fiber sheet travels. A supply of oxidizing gaseous fluid is provided within the enclosure, that further includes one heat treatment zone and, at opposite ends of the enclosure, a temperature-raising zone and a temperature-lowering zone. The inlet and outlet sections are fitted with airlocks connected to cooling and suction devices.

Abstract: A method of activating a fiber sheet comprising carbonized filaments or spun carbonized yarn includes causing the sheet to travel horizontally through a furnace including at least one horizontal heat treatment zone in which there is maintained a regular and uniform temperature lying in the range of 800.degree. C. to 1000.degree. C. at a linear speed lying in the range 1 to 5 cm/min. over the length of the heat treatment zone and maintaining at least in the zone a constant flow of an oxidizing gaseous fluid that is uniformly distributed therein and at a pressure close to atmospheric pressure. A temperature-raising zone and a temperature-lowering zone are located at opposite ends of the treatment zone relative to the travel direction of the sheet and inlet and outlet sections of the treatment zone are fitted with air locks having cooling and suction systems.