Abstract: A coating for providing anti-oxidation protection is formed at least on the surface of the material and it comprises a refractory phase which is formed mainly of the refractory silicide Ti.sub.(0.4-0.95) Mo.sub.(0.6-0.05)Si.sub.2, and which has a branching microstructure forming an armature within which a healing phase is distributed that is constituted by a eutectic which is formed mainly of unbound silicon, of the silicide Ti.sub.(0.4-0.95)Mo.sub.(0.6-0.05) Si.sub.2, and of at least the disilicide TiS.sub.2. The coating is obtained from a mixture of powders that is deposited on the surface of the material and that is subjected to heat treatment under an inert atmosphere.

Abstract: The supersonic distributor for the inlet stage of a turbomachine comprises an outer case, a hub, and a set of peripheral blades disposed in a ring and attached to the hub to provide supersonic speed fluid passages between the blades to transform a flow at high pressure and low speed into a supersonic flow at low pressure. The blades are disposed radially in regular manner within a fluid feed torus. In a section developed on a line corresponding to a given radius, i.e. in a blade-to-blade plane, the blades define a profile in the form of a two-dimensional half-nozzle. This profile has a rectilinear upstream portion, a bulge defining a throat for accelerating the flow to a Mach number equal to 1, the throat being of section that varies with radius, and a downstream portion which terminates in a region of uniform flow at a trailing edge which may be truncated perpendicularly to the axis of rotation.

Abstract: A method of manufacturing a composite material in the form of an annular tube by winding on a mandrel both a reinforcing fiber fabric and a sheet of matrix material, comprising the following steps: 1) preheating the mandrel to a predetermined temperature; 2) fixing the reinforcing fiber fabric and the sheet of matrix material to the mandrel; 3) causing the mandrel to rotate at a nominal speed to wind the fabric and the sheet simultaneously, the fabric and the sheet being subjected to a nominal tension; 4) actuating heating means for heating the material and cooling means for cooling the mandrel; 5) when the tube reaches the desired diameter, stopping both the heating means and the rotation of the mandrel; 6) after a determined duration that is sufficient for; bringing the temperature of the mandrel to the predetermined preheating temperature, stopping the cooling means; and 7) dismounting the mandrel.

Abstract: The present invention relates to an injector of tricoaxial structure comprising a body that is circularly symmetrical about an axis of symmetry, said body being provided with a plurality of injection elements having axes parallel to said axis of symmetry and passing through an injection wall fixed to said body and separating said injector from a combustion member to which it is coupled. According to the invention, each of said injection elements comprises a central injection channel fed with a second propellant and an annular injection slot surrounding said central channel and fed with a first propellant, an additional annular injection channel for the second propellant being formed by a space that exists around each injection element between its side wall and said injection wall, such that the sheet of first propellant flowing from said annular slot is engaged between the central jet and the outer sheet, each of which delivers the second propellant.

Abstract: The substrate (10) is placed in an enclosure (12) and is heated so as to establish therein a temperature gradient such that the substrate has a higher temperature in portions that are remote from its exposed surfaces than at its exposed surfaces. A reaction gas constituting a precursor for the material to be infiltrated is admitted into the enclosure, with formation of the material being enhanced in those portions of the substrate that are at higher temperature. At the beginning of the infiltration process, and at least during the major portion thereof, substrate heating is controlled in such a manner as to maintain the temperature of its exposed surfaces at a value that is no greater than the minimum temperature for the reaction gas to deposit the material that is to be infiltrated, while portions of the substrate that are remote from its exposed surfaces are at a temperature that is greater than the minimum temperature for deposition.

Abstract: The method comprises forming a coating on the product of composite material to be protected. The coating contains a mixture of a non-oxide refractory ceramic in finely-divided form, at least one refractory oxide in finely-divided form and providing healing properties by forming a glass, and a binder constituted by a polymer that is a precursor of a non-oxide refractory ceramic. The polymer is transformed into a ceramic to obtain a protective layer comprising a non-oxide refractory ceramic phase and a healing phase which together constitute two interpenetrating lattices. After the ceramic precursor polymer has been transformed, a final heat treatment step may be performed at a temperature higher than the softening or melting temperature of the healing phase.

Abstract: The present invention relates to a method of thermally and mechanically protecting cables and bundles of cables by use of a sheath braided directly around the element to be protected using a braiding yarn constituted by a plurality of elementary strands formed by interlacing synthetic fibers obtained after cracking and spinning an aramid fiber and a carbonizable oxidized organic fiber. The carbonizable oxidized organic fiber constitutes the major portion of the synthetic fibers making up the elementary strand for the braiding yarn. The invention also provides a thermal and mechanical protective sheath for cables and bundles of cables obtained by the method. In order to improve certain mechanical or thermal characteristics of the sheath, it may be associated with a material made of a fiber additional to said two synthetic fibers, in order to form the elementary strand, or indeed the sheath braided in this way may itself be covered in additional braiding based on aramid fibers.

Abstract: A sealed passage is formed in a part of refractory composite material by inserting a tubular metal lining in a hole in the part, brazing material being interposed between the lining and the hole, and by heating to braze the metal lining to the wall of the hole, so that the metal lining defines a sealed passage (38). The metal lining (39) is plastically deformable under the conditions of use of the part such that differential expansion of thermal origin between the refractory composite material and the metal lining can be compensated by plastic deformation of the lining.

Abstract: The present invention relates to a parallel-sheet injector provided with a body about an axis to which there is coaxially connected at least one annular injection element comprising a central annular injection slit surrounded by two other annular injection slits. The central annular slit is fed with a second propellant which enters at the top of the injection element level with said central slit and the other annular slits are fed with a first propellant which enters at the base of the injection element, on either side of the central slit, and passes through an annular homogenization cavity from which it flows towards the annular slits surrounding the central injection slit. The invention also relates to injection elements which may be used within the scope of this injector.

Abstract: The present invention relates to an electrically-controlled vacuum-enclosed cryogenic valve including firstly a body receiving the seat for a valve member, and inlet and outlet channels for a cryogenic fluid, the body and the channels being disposed in an enclosure in which a vacuum is created, and secondly a moving valve member whose stem is actuated by moving core and a control electromagnetic winding, a return spring pressing the valve member against its seat in the absence of excitation. In accordance with the present invention, the moving core of such a valve is placed inside the vacuum enclosure which is secured to a a sleeve that separates the moving core from the control electromagnetic winding, which is placed outside the enclosure. Preferably, a bellows that is secured both to the valve body and to the stem implements sealing between the vacuum enclosure and the fluid flowing through the channels.

Abstract: A sealed passage is formed in a part of refractory composite material by inserting a tubular metal lining in a hole in the part, brazing material being interposed between the lining and the hole, and by heating to braze the metal lining to the wall of the hole, so that the metal lining defines a sealed passage (38). The metal lining (39) is plastically deformable under the conditions of use of the part such that differential expansion of thermal origin between the refractory composite material and the metal lining can be compensated by plastic deformation of the lining.

Abstract: A part is made of a composite material having an alumina matrix by impregnating a fiber texture with a fluid composition containing a liquid precursor of alumina, a thermoplastic resin, and a suspension of alumina powder, and subsequently convening the precursor into alumina. Additional solid fillers may be added to the impregnation composition. The impregnated fiber texture is preferably made by draping and molding plies that are pre-impregnated with said composition.

Abstract: The present invention relates to an ion-optical system for a gas-discharge ion source, the system comprising a screen grid and an accelerator grid each constituted by a respective frame and a set of wires held parallel by supports and fixed to said frames by means of springs, the frames and the grids being assembled together by means of insulators to which they are fixed. According to the invention, the system further comprises a decelerator grid constituted by a frame and a set of wires, the frame of the decelerator grid being engaged in the frame of the accelerator grid and being separated therefrom by insulators. The supports of the wires are constituted either by a comb-shaped plate or by rollers with at least one of the rollers installed in the screen grid being shaped so as to be barrel-shaped, having a larger diameter in its center than at its ends.

Abstract: The loader device comprises a cartridge-carrying carousel provided with a set of cartridge-holders in which sealed closed cartridges are mounted in removable manner, each cartridge being designed to contain a sample for processing in a space furnace, the device further comprising a control mechanism for imparting indexed rotary drive to the cartridge-holders. The carousel is mounted to one side of the furnace in such a manner that its axis of rotation is parallel to longitudinal axis of the furnace. Each cartridge-holder of the carousel co-operates with a transfer mechanism that includes a translation arm extending perpendicularly to the axis of rotation of the carousel to enable each cartridge to be brought successively into a working position in which the axis of the cartridge is in alignment with the longitudinal axis of the furnace. The control mechanism for imparting rotary drive to the cartridge-holders and the transfer mechanism are activated alternately by a single electric motor.

Abstract: A thermal shielding element which includes a hollow rigid panel in the form of a shell made of a thermostructural composite including fiber reinforcement densified by a matrix, and a thermal insulant filling the panel is obtained by making a rigid block (20) of thermally insulating material of low density, the block having an outside surface whose shape corresponds to the shape of an inside surface of the panel, a fiber preform (11) constituting the reinforcement of the composite material is formed on the block of insulating material, and the fiber preform is densified with the material that constitutes the matrix of the composite material.

Abstract: To manufacture a turbine wheel having blades made of a ceramic or composite material and inserted into a metal hub, firstly blades (16) are manufactured that are right cylindrical, each blade having a base (18) through which a hole is formed; a cylindrical ring (20) is formed, the ring being provided with orifices through which the bases (18) of the respective blades (16) are inserted; the blade bases (18) are successively threaded onto an open annular rigid metal wire (30); the resulting assembly (16, 20, 30) is disposed inside a sealed housing (161); hot isostatic compaction is performed so as to compact a metal alloy in powder form (41) inside the sealed housing (161) so as to make the hub of the turbine wheel (100) while embedding the blade bases (18) and the metal wire (30) by using the powder metallurgy technique; and the outside portion of the sealed housing (161) delimiting the hub of the turbine wheel (101) is machined. Application, in particular, to the field of aeronautical or space engineering.

Abstract: The present invention relates to a system for feeding the engines of a space vehicle with at least one liquid propellant, the system comprising for the purpose of storing said liquid propellant under a pressure greater than the feed pressure, firstly a main tank having no liquid expulsion device, and secondly an auxiliary tank that is smaller than the main tank and that is provided with a device for separating the liquid phase from the gas phase, switching means enabling the auxiliary tank to be selectively refilled with liquid propellant from the main tank; such that liquid propellant that is free from pressurization gas bubbles can always be delivered regardless of the flight conditions of the vehicle, and in particular when it is not possible to take said liquid propellant from the main tank.

Abstract: The pyrolytic carbon lamellar interphase is formed on the reinforcing fibers inside a chamber in which a plurality of successive cycles is performed, each cycle comprising: injecting a reaction gas in which the pyrolytic carbon precursor is selected from alkanes, excluding methane taken as a sole component, alkenes, alkynes, and aromatic hydrocarbons, and mixtures thereof; the gas is maintained inside the chamber for a first predetermined time period to form an interphase layer of controlled thickness of nanometer size; the gaseous reaction products are then evacuated during a second time period; the cycles being performed consecutively in the chamber until the thickness desired for the interphase has been obtained, thereby achieving a lamellar interphase that is highly anisotropic, whose lattice fringe texture has distorted fringes of total length (L.sub.2) not less than 4 nanometers on average with maximum values exceeding 10 nanometers.

Abstract: A method of manufacturing a honeycomb structure of thermostructural composite material comprising a fiber reinforcing fabric densified by a matrix, the fibers of the reinforcing fabric being of a material selected from carbon and ceramics, as is the matrix, the method comprising the following steps:making a three-dimensional fiber fabric by means of superposed two-dimensional plies that are bonded together by means of fibers passing through the plies;making slit-shaped cuts in a staggered configuration through the plies, and through the entire thickness of the fabric;stretching the cut fabric in a direction that is not parallel to the cuts but that is parallel to the plies so as to form cells whose walls are constituted by the lips of the cuts; andwhile the cut texture is held in the stretched state, densifying it using the matrix-constituting material to obtain a rigid honeycomb structure of thermostructural material.

Abstract: A process and a device for the optical measurement of vibrations of rotating turbine blades moving with a specified speed of rotation. In one embodiment, the process comprises the steps of generating three reference signals in response to the detection, by an optical detector, of the passing of a marking made on the hub of a turbine wheel; detecting measurement signals, by another optical detector, in response to the passing of another marking made on at least one of the parts of a turbine blade, the blade undergoing oscillation; determining the time offsets existing between each of the reference signals and each of the measurement signals, these offsets being, in the absence of oscillations of the blade, zero or equal to specified constant values; and calculating the amplitude, frequency and phase components of blade vibration from the various offsets recorded.