Abstract: A centrifugal pump with an open-faced impeller for conveying a working liquid, the pump comprising at least one open-faced impeller provided with blades placed inside a casing defining a suction pipe facing the bottoms of the blades in the vicinity of a central shaft that drives the impeller and forming a part of a rotary assembly, and a delivery pipe fitted with a fixed diffuser disposed facing the peripheral ends of the blades. An active axial balancing system for the rotary assembly, which balancing system is integrated in the impeller and comprises a balancing chamber interposed between the rear face of the body of the impeller and an outer rear portion of the casing.

Abstract: The present invention relates to synthetic phyllosilicates having a lamellar structure of the type T--O--T devoid of OH.sup.- and F.sup.- ions. Said phyllosilicates are very resistant to oxidation and possess a high thermal stability. The invention further relates to a process for the preparation of said phyllosilicates.

Abstract: A loader device for an automatic space treatment furnace having a longitudinal axis and means for driving the furnace in guided translation along said longitudinal axis. The loader device is disposed in the vicinity of the furnace and comprises both a cartridge-carrying carousel fitted with a set of cartridge holders removably receiving sealed closed cartridges each designed to contain a sample for treatment in said space furnace, the cartridges being disposed in the carousel parallel to its axis of rotation, and a control mechanism for imparting indexed rotary drive to the cartridge holders. The carousel is itself mounted relative to the furnace in such a manner that its axis of rotation forms a predetermined angle a relative to the longitudinal axis of the furnace, and each cartridge holder of the carousel co-operates with a tilting mechanism to enable each cartridge to take up a working position in which the axis of the cartridge is tilted through said predetermined angle .alpha.

Abstract: An enclosure containing hot gases cooled by transpiration includes means for applying a cooling fluid, said means comprising a hydraulic calibration sheath applied on the outside face of a porous wall that forms the inside portion of the enclosure, said sheath being made of a material that is proof to the cooling liquid and that is perforated by a multiplicity of microperforations having a distribution density that varies progressively over various different portions of said wall so as to provide greater perforation density wherever the heat flow to be cooled reaching the porous wall is high, and a cooling fluid feed volume formed between the sheath secured to the porous wall and an outer sealing envelope so as to apply a pre-determined flow rate per unit of area to said sheath in various different zones of the wall of the enclosure, spacers being interposed between the hydraulic calibration sheath and the outer sealing envelope.

Abstract: The gas is preheated by means of at least one screen disposed transversely relative to the flow of gas penetrating into the enclosure. The screen is provided with passages for the flow of gas and is fixed inside a peripheral wall to define a channel to enable the gas to flow through the preheating apparatus, it is also provided with fins which project from its surface, the screen and the fins being made of a refractory sheet material, in particular a sheet of laminated graphite.

Abstract: The present invention relates to an electrically controlled leakproof valve having a fluid feed channel and at least one channel for delivering said fluid, rotary displacement of a distributor plug in said valve being under the control of an actuator. The actuator comprises an axially pierced rotor through which the fluid from the feed channel flows without headloss, the actuator being connected to the valve body in leakproof manner without using dynamic sealing devices. The present leakproof valve is particularly suitable for use in corrosive environments, and in particular under cryogenic conditions.

Abstract: The damping system comprises at least one resonant acoustic cavity disposed around the combustion chamber and having a shape and dimensions such that it functions simultaneously as a quarter-wave resonator and with tangential coupling the resonant acoustic cavity comprises:a) a main annular part whose half axial section has a very elongate shape with a width dimension "e" which is very small compared to its longitudinal dimension "L.sub.1 " which extends substantially parallel to the axis of symmetry of the combustion chamber, the mean radius "R" of the main annular part being close to the equivalent radius of modes of oscillation to be damped, and b) an annular coupling part which originates from the main annular part and which opens into the combustion chamber near to a longitudinal or radial pressure anti-node, the annular coupling part having a length "L.sub.2 " in a half axial section and a width dimension "h" very much less than the sum of the longitudinal dimension "L.sub.

Abstract: A method of densifying a porous substrate by means of a matrix containing carbon, for obtaining an article made of a composite material, the method comprising the following steps:providing on one side of a substrate to be densified a slip containing submicron carbon powder;establishing a pressure difference to force the slip through the substrate;filtering the liquid that has passed through the substrate to retain the carbon powder inside the substrate; andwhen densification of the substrate by means of the carbon powder has terminated, drying the densified substrate and transforming a carbon precursor introduced into the substrate into carbon by carbonization, thereby binding the powder constituting the matrix.

Abstract: A gun barrel lining made of composite material having refractory fiber reinforcement and a ceramic matrix, the fiber reinforcement comprises a cylindrical inner portion constituted by a three-dimensional fiber texture and a cylindrical outer portion surrounding the inner portion and having the same axis, the outer portion being constituted by a strip wound around the inner portion, and the inner and outer portions being codensified by the ceramic matrix.

Abstract: A fiber preform is initially consolidated by being impregnated with a thermosetting impregnation composition that contains a ceramic precursor, and by heat treatment at the end of which the precursor has been transformed into ceramic, without passing through a meltable phase. The consolidated preform is then densified. The impregnation composition is constituted by a mixture of a thermosetting monomer and a ceramic precursor polymer, and the monomer is cross-linked during the heat treatment so as to achieve "in situ" cross-linking of the polymer mixture prior to transforming the precursor into ceramic.

Abstract: Anti-oxidation protection for a silicon compound under both an active oxidation condition and a passive oxidation condition is achieved by forming an intermediate layer devoid of the element silicon between the surface of the silicon compound ceramic, such as SiC, and a silica based vitreous outer layer, such as SiO.sub.2, to be subsequently deposited. The intermediate layer is made of alumina (Al.sub.2 O.sub.3) or an alumina precursor, so as to constitute a reaction barrier between the silicon compound and the silica outer layer on the one hand, and trap any amount of silica that may be formed by an oxidation of the silicon compound.

Abstract: A structural connection is obtained between elements (21, 22) of the reinforcement texture to be assembled by using at least one blocking means (23). The latter is made of a fibrous texture that is compacted prior to being inserted in a corresponding lodging formed in at least one of the elements of the reinforcement texture in order to conform with the shape of the lodging. The blocking means (23) then locks itself into the lodging by relaxation of its fibrous texture, as a result of a removal of the prior compacting. The blocking means can be in the form of a dowel (23) inserted inside aligned lodgings formed in the elements (21, 22) of the reinforcement texture to be assembled, or may alternatively be part of one of the elements of reinforcement texture to be assembled.

Abstract: The thermostructural composite material is produced by forming a fibrous preform made from refractory fibers coated with a sizing agent. The preform is densified by a refractory matrix, in particular ceramic, while a carbon interphase is provided between the fibers and the matrix. The fibrous preform is made from refractory fibers coated with a sizing agent of the type that leaves behind a carbon residue upon thermal decomposition. The carbon interphase is produced by the thermal degradation of the sizing agent, occurring for example after the preform is made. The sizing agent is chosen among phenolic, acrylic and cellulose resins, and in particular carboxymethylcellulose.

Abstract: The deployment mechanism comprises three identical operative assemblies mounted on a fixed main frame. Each operative assembly comprises a linear actuator and first and second links disposed in such a manner as to ensure self-locking in a deployed position by causing the axes of the following three hinges to pass to or slightly beyond a dead point where they are in alignment: the hinge between the main frame and a first zone of the first link; the hinge between the upstream end of the second link and a second zone of the first link; and the hinge between the downstream end of the second link and a link support mounted on the deployable portion of the nozzle. The actuator is secured and anchored to a non-deployable portion of the nozzle and it includes a drive member whose free end is hinged to a third zone of the first link, and it is deactivated in both of the final positions, i.e. when the deployable portion is deployed and when it is retracted.

Abstract: The process is particularly well suited to the manufacture of composite materials, where a fibrous reinforcement texture is to be impregnated by a densifying matrix, and comprises the steps of:preparing a slurry containing a solid charge in the form of finely divided particles dispersed in a carrier liquid, which preferably contains an organic compound,placing a substrate inside an enclosure,creating a vacuum inside the enclosure, andcausing the slurry to pass through the substrate by means of a pressure difference.Uniformity of charge integration is ensured by forcing the slurry to pass through the substrate several times, in successively opposite directions. The concentration of solid charge in the slurry can be determined as a function of an intended charge percentage by volume in said substrate.

Abstract: The retractable-gasket ball valve includes sealing means fixed on the valve body, and including, in particular, a gasket for providing sealing between the shutter member and the valve body when the shutter member is in a closed position, and further including a slide for causing said sealing means to move between a retracted position which is also a rest position in which the sealing means is spaced spart from the spherical shutter member, and a contact position in which the gasket is pressed against the shutter member. The valve includes a first resilient element of low stiffness which tends to separate the sealing means from the shutter member when the valve is brought to its open position, and a second resilient element of relatively greater stiffness which is put under tension by the slide a few degrees before the mechanical closure position of the valve when the gasket is in contact with the shutter member, and which exerts control pressure on said gasket in contact with the shutter member.

Abstract: To make a laminated flexible bearing constituted by rigid reinforcing layers made of composite material alternating with layers of rubber or elastomer, each reinforcing layer is formed by winding a resin preimpregnated thread directly on the underlying layer of rubber or elastomer. Advantageously, the flexible bearing is made by alternating layers formed by winding a resin pre-impregnated thread and layers formed of non-vulcanized rubber or elastomer, after which the resin is polymerized and the rubber or elastomer is vulcanized simultaneously.

Abstract: A valve with redundancy on closing comprises a single valve body, first and second substantially hemispherical hollow valve members disposed inside said valve body, each including an orifice allowing fluid to pass therethrough, independent first and second rotary drive means for the first and second hemispherical valve members, and first and second sealing devices each comprising at least one annular gasket and each associated with a respective one of the first and second valve members, the first and second valve members being of different diameters and one being nestable inside the other. It is preferable for at least one of the sealing devices to be retractable so as to avoid confining fluid inside the valve.

Abstract: The manufacture of a refractory composite material protected against corrosion and comprising fibrous reinforcement densified by a matrix, comprises a step of forming, either within the matrix or at its surface, at least one continuous layer constituted by a ternary silicon-boron-carbon system obtained by chemical vapor deposition or infiltration. The elements silicon and boron are thereby distributed uniformly, with the boron content in the Si-B-C system being not less than 5% in atom percentage.

Abstract: The surface tension tank is designed to feed a liquid propellant to a main engine and to at least one auxiliary engine or receiver of a space vehicle or satellite. The tank comprises a common shell containing at least two compartments of different sizes that are separated by a diaphragm provided with at least one strainer for providing communication between the large compartment and the small compartment. A pressurization gas feed orifice opens out into the large compartment. A liquid expulsion device is placed in the small compartment, and means for delivering liquid to the members to be fed are essentially disposed along a direction that differs little from the direction of the main acceleration imparted by the main engine, in such a direction as to accelerate liquid flow therealong.