Abstract: An acoustic attenuation panel including: a main layer made of a porous material and having two opposite faces; a coating layer arranged on one of the two faces of the main layer; an adhesive film, arranged at the interface between the main layer and the coating layer to assemble same. The main layer is a body made of melamine resin foam having a density between 6 and 6.8 kg/m3 and a porosity rate between 0.978 and 0.984; the coating layer is a fabric with a density between 484 and 526 kg/m3 and a porosity rate between 0.771 and 0.

Abstract: The invention relates to a method of and an installation for the heat treatment of steels, such as heating before hardening, annealing, and carburization, which heat treatment is carried out in a furnace in the presence of a protection or carbon-enrichment atmosphere which flows continuously through the furnace, the atmosphere being obtained by the mixture, before its introduction into the furnace, of a carrier gas including nitrogen and possibly hydrogen, and an active gas constituted by a hydrocarbon, the mixture containing at least 0.2% by volume of hydrocarbon.The active gas may be constituted by ethylene, ethane or acetylene and the treatment is carried out at a temperature between 850.degree. and 1050.degree. C.The installation includes a device for analyzing the atmosphere at the furnace outlet, this analyzer actuating a regulating valve for the inlet flow of active gas through a servo-mechanism, in dependence on the proportion of carbon in the treated steel.

Abstract: The invention relates to a method of and an installation for the heat treatment of steels, such as heating before hardening, annealing, carburization and carbo-nitridation, carried out in a furnace in the presence of a protection or carbon-enrichment atmosphere which flows continuously through the furnace, the atmosphere being obtained by the mixture, before its introduction into the furnace, of a carrier gas including nitrogen and possibly hydrogen, and an active gas constituted by a hydrocarbon, the mixture containing at least 0.2% by volume of hydrocarbon.The active gas may be constituted by ethylene, ethane or acetylene and the treatment is carried out at a temperature between 700.degree. and 1050.degree. C.The installation includes a device for analyzing the atmosphere at the furnace outlet, this analyzer actuating a regulating valve for the inlet flow of active gas through a servo-mechanism, in dependence on the proportion of carbon in the treated steel.