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 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 metal static gasket forms an annular body about an axis ZZ′. The profile of the gasket in axial half-section presents an elongated S-shape and comprises a lateral first portion defining the inner peripheral surface of the gasket, a lateral second portion defining the outer peripheral surface of the gasket, said lateral first and second portions being offset from each other along the direction of the axis of the gasket. The gasket also presents a curved third portion of undulating shape having a substantially rectilinear first contact region at one of its ends, and a curved fourth portion of undulating shape having a substantially rectilinear second contact region at one of its end extending perpendicularly to the axis of the gasket in such a manner that the gasket provides sealing between two flanges solely by means of the axial pressure exerted by the flanges.

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 thrust device comprises a valve body (20) having a chamber (24) surrounding part of the needle, at least one gas admission opening (27) opening out into the chamber, and a gas outlet opening (25) opening out into the chamber and defined by a wall portion which co-operates with a nose portion (14) of a moving needle (10) to define an outlet section for gas leaving the chamber. Actuator means (40, 41, 43) control the position of the needle in the valve body by acting on a rear end portion of the needle. The nose (14) of the moving needle (10) has an aerodynamic concave profile (15) and the wall portion (29) which defines the outlet (25) from the chamber is shaped in such a manner as to be capable of directing the exiting gases essentially against the concave side of the nose of the needle, which needle acts as the main member for taking up thrust.

Abstract: A regenerative circuit structure is built up by implementing the following steps in particular: an intermediate layer is made on a support core representing the inner profile of the structure; a series of channels regularly distributed around the core is made with the channels opening to face the intermediate layer, each of the channels being provided with a soluble insert; the support core is preheated and the body of the structure is made by thermal spraying under a vacuum; channels are machined in the body from the outside, and said channels are filled by means of soluble inserts; a closure layer is formed to close the channels in the body, and an outer envelope is formed by thermal spraying under a vacuum, after preheating; and all of the soluble inserts and the intermediate layer are eliminated.

Abstract: The piece made of composite material comprises a plate and a plurality of stiffeners integrally formed with the plate. A metal wall is fixed to the edges of the stiffeners and is provided with passages for circulating the fluid. The plate exposed to the heat flux radiates towards the metal wall through the gaps between the stiffeners, and it also performs the structural function. The invention can be used with structures that are exposed to very high heat flux: the walls of jet combustion chambers, the walls of space plane vehicles, the walls of nuclear fusion reactors.

Abstract: The invention provides a process for checking the bonding of the cellular core of a honeycomb to a skin, said process comprising the steps of: using a light source to illuminate a so-called illuminated zone on the free surface of the honeycomb so as to illuminate the interior of the cells opening out into said illuminated zone, and detecting the emergent light exiting the cells in a so-called observed zone. The minimum distance between said illuminated zone and said observed zone is denoted E and defines a direction D, the distance E being at least equal to the width L1 of the cell mouths measured in the direction D, so as to make it impossible for the illuminated zone and the observed zone to be simultaneously above the mouth of one and the same cell. The invention also provides an instrument for implementing the process.

Abstract: A ceramic heat barrier coating is deposited on a substrate so that the coating has a columnar growth pattern which is interrupted and repeated a number of times throughout its thickness by successive regermination of the ceramic deposit. The regermination is obtained by a vapor phase deposition process wherein a polluting gas is introduced intermittently during the deposition of the ceramic. The resulting ceramic coating has a lower thermal conductivity than conventional columnar ceramic coatings.

Abstract: A diverging ring is displaceable between a retracted position in which it surrounds a first portion of a diverging part and a deployed position in which it is connected to a downstream end of the first portion. A deployment mechanism causes the diverging ring to move from its retracted position to its deployed position under drive from an actuator. A temporary structure, or “insert”, is placed inside the diverging ring so as to transform the diverging section thereof into a non-diverging section, at least over the major portion of the length of the diverging ring, the insert being eliminatable on or after the diverging ring coming into its deployed position.

Abstract: The invention concerns (1) thermochemically treating by pack-cementation a carbon-containing material, which may have an open porosity, to generate a refractory carbide coating on its surface and, if the material is porous, within the material; and (2) the use of specific alloys as a pack for thermochemically treating carbon-containing materials, optionally with an open porosity, in a halogenated atmosphere. Pack-cementation is carried out under reduced pressure using an element E (to be transported and to be reacted with the carbon in the material to generate the expected carbide) alloyed to an element M, and using a halide (chloride or fluoride, preferably a fluoride) of the same element M, of low volatility, present in the solid form.

Abstract: The present invention provides a method of densifying porous structures by chemical vapor infiltration. In characteristic manner, said densification method is implemented using toluene as a precursor for carbon. Said toluene is generally used mixed with at least one carrier gas.

Abstract: The rack is made essentially out of thermostructural composite material and comprises a baseplate (12), a partition (14) extending above the baseplate, and a plurality of support arms (20) fixed to the partition and extending substantially horizontally therefrom to their own free ends, so that parts to be treated (A) can be supported in cantilevered-out positions on said arms.

Abstract: A steerable nozzle for a reaction engine comprises a fixed portion (1) for fixing to the engine, a moving portion (2) hinged to the fixed portion, control means (3) for controlling the moving portion, and one or more resilient assemblies (4) disposed between the fixed portion and the moving portion. The nozzle is characterized in that each resilient assembly comprises at least one fixed resilient stud (40) having a first end secured to the fixed portion and a second end, opposite from the first end, secured to a rigid piece (42); and at least one moving resilient stud (41) having a first end secured to the moving portion and a second end, opposite from the first end, secured to said rigid piece (42). In addition, each moving resilient stud (41) is offset relative to each fixed resilient stud (40) in a circumferential direction of the nozzle.

Abstract: A steerable nozzle for a reaction engine comprises a fixed portion (1) for connection to the engine, a plurality of steerable flaps (21) mounted on one end (11) of the fixed portion, and flap steering means (3, 4, 22, 31). The nozzle is characterized in that the flap steering means comprise a resilient ring (3) having a first circumference secured to said end (11) of the fixed portion and a second circumference connected to the flaps (21), and control means (4) for moving the second circumference of the resilient ring.

Abstract: An axisymmetric, converging-diverging and swiveling exhaust nozzle includes converging flaps (3) driven by an axially displaceable drive ring (7). The diverging flaps (15) are connected by linkrods (20) to a pivoting ring (21). The pivoting ring (21) is mounted in swiveling manner on a spherical segment (30) fixedly joined to the structure (13). In an embodiment variation, the spherical segment (30) is mounted by a sliding connection on the stationary structure. A rotation-blocking system (33) precludes the rotation of the spherical segment (30) about the axis X of the turbojet engine.

Abstract: A fuel valve for a fuel flow injection circuit, operating on electrical energy rather than hydraulic energy. The fuel valve has a valve body, a first fuel inlet opening, and a distribution assembly having a plug rotating in a bushing, the plug and bushing each having an opening slit. The valve body includes a fuel outlet opening section made by an overlapping area between the opening in the bushing and the opening in the plug. A plug position unit is provided to control a position of the plug in rotation, and the plug position unit is disposed in the valve body. The valve body further contains an electric motor that drives a rotation of a reduction gear assembly, the reduction gear assembly comprising an input shaft and an output pinion. The plug comprises a toothed sector engaging on the splines of the reduction gear assembly output pinion such that rotating the electric motor causes a rotation of the plug.

Abstract: A method of improving the oxidation and corrosion resistance of a superalloy article comprises providing a superalloy substrate having a sulphur content which is less than 0.8 ppm by weight, and depositing on the substrate a protective antioxidation coating having a sulphur content also less than 0.8 ppm by weight. A heat barrier layer may also be provided by depositing on the protective anti-oxidation coating a ceramic coating of columnar structure.

Abstract: The seal is composed of butt-jointed segments (1) in which the bearing surface (18) on a rotating part (2) subject to wear, includes a hollow chamber (20) communicating through calibrated orifices (22) with a high pressure containment (8). Therefore, it fills up with gas which tends to force it away from the surface, thus reducing the contact pressure without introducing excessive leaks.

Abstract: A retaining arrangement is provided for retaining a bearing around a stub shaft having a machined cavity and which includes a ring forming a stop for the bearing nut and a locking piece.