摘要:
The invention relates to a method of fabricating a composite material part comprising fiber reinforcement densified by a matrix, the method comprising the steps of: making a fiber preform consolidated by impregnating (S4) a fiber texture made up of yarns with a liquid consolidation composition containing a precursor for a consolidating material, and by transforming (S7) the precursor into consolidating material by pyrolysis so as to obtain a consolidated preform that is held in shape; and densifying (S8) the consolidated fiber preform by chemical vapor infiltration; the method being characterized in that it includes, prior to impregnation (S4) of the fiber texture with the consolidation liquid composition, a step of filling (S2) the pores of the yarns of said fiber texture by means of a filler composition.
摘要:
Multilayer weaving is used to form a fiber blank having a longitudinal direction corresponding to the longitudinal direction of the vane to be made and comprising across its thickness a first woven portion with a plurality of layers of yarns interlinked by weaving, and also a second and third woven portions. The first portion is situated between the second and third portions and interlinked thereto by weaving over only a fraction of its longitudinal dimension. A preform for the vane is formed by folding out, on either side of the first portion, segments of the second and third portions not interlinked with the first portion, by shaping the first portion to form a preform portion for the airfoil of the vane, and by shaping the folded-out segments of the second and third portions to form preform portions for the inner and outer platforms of the vane to be fabricated.
摘要:
In order to protect a substrate having at least a portion adjacent to a surface that is made of a refractory material containing silicon, while the substrate is in use at high temperature in a medium that is oxidizing and wet, there is formed on the surface of the substrate an environmental barrier that contains no boron and that has at least one layer that is essentially constituted by a system of oxides formed by at least one rare earth oxide, silica, and alumina, and that is capable of self-healing by maintaining the presence of at least one solid phase in a temperature range extending up to at least 1400° C. approximately.
摘要:
An assembly comprising first and second parts made of composite material held one against the other by at least one fastener system comprising a bolt having a flat head from which there extends a threaded portion, and a nut having a flat head from which there extends a shank including tapping suitable for co-operating with the threaded portion of the bolt. The head of the bolt bears against a countersink formed in the first part. The head of the nut bears against a countersink formed in the second part. The fastener system is suitable, during axial expansion of the fastener system, for causing each head to tilt towards the countersink in which it is housed.
摘要:
A method of smoothing the surface of a ceramic matrix composite material part that presents a surface that is undulating and rough. The method includes depositing a refractory vitreous coating on the surface of the part, the vitreous coating essentially containing silica, alumina, baryte, and lime.
摘要:
The method comprises: using chemical vapor infiltration to form a first continuous interphase on the fibers of a fiber structure made of refractory fibers, the interphase having a thickness of no more than 100 nanometers; impregnating the fiber structure with a consolidation composition comprising a carbon or ceramic precursor resin; forming a fiber preform that is consolidated by shaping the impregnated fiber structure and using pyrolysis to transform the resin into a discontinuous solid residue of carbon or ceramic; using chemical vapor infiltration to form a second continuous interphase layer; and densifying the preform with a refractory matrix. This preserves the capacity of the fiber structure to deform so as to enable a fiber preform to be obtained that is of complex shape, while nevertheless guaranteeing the presence of a continuous interphase between the fibers and the matrix.
摘要:
A turbine nozzle comprises a plurality of composite material vanes, each vane comprising an inner platform, an outer platform with attachment tabs on the outside, and at least one airfoil extending between the inner and outer platforms and secured thereto. The attachment tabs of the vanes are engaged on a metal assembly ring supporting all of the vanes, extending continuously along the outer platforms of adjacent vanes, and forming a distinct assembly part between the vanes and a turbine casing.
摘要:
A method for fabricating turbine engine blade or vane made of composite material includes: performing three-dimensional weaving to make a single-piece fiber blank; shaping the fiber blank to obtain a single-piece fiber preform having a first portion forming a preform for at least a blade/vane airfoil, at least one second portion forming a preform for an inner part of a blade/vane inner platform or for an outer part of a blade/vane outer platform, and at least one third portion forming a preform for an outer part of a blade/vane inner platform or for an inner part of a blade/vane outer platform; and densifying the fiber preform with a matrix to obtain a composite material blade, and forming a single piece with an inner and/or outer platform(s) incorporated therein.
摘要:
A method of fabricating a composite-material turbomachine blade having platform incorporated therein includes separately making a blade platform element that includes rigidified fiber reinforcement and that has a shape close to that of a platform of the blade to be fabricated, with at least one opening being formed through the platform element. The opening has the shape of the profile of the airfoil of the blade to be fabricated. Three-dimensional weaving is used to make a flexible fiber blank as a single piece that includes blade airfoil-and-root preform portions. The platform element is engaged, via its opening, on the flexible fiber blank while deforming it so as to assemble the platform element with the fiber blank. The fiber blank is shaped together with the platform element assembled thereon to obtain a blade preform of a shape that is close to the shape of the blade to be fabricated. After shaping, the blade preform is consolidated in its shape in a shaper. Additionally, final densification of the consolidated blade preform is performed in order to obtain a composite-material blade having an incorporated platform.
摘要:
The subject of the present invention is a pyrotechnic method for generating gas at two successive flow rates—a first flow rate then a second flow rate, said first flow rate being higher than said second flow rate—which comprises: the combustion of a first pyrotechnic charge (10) in a first combustion chamber (1) discharging into a second combustion chamber (2) via at least one nozzle (3); and the combustion of a second pyrotechnic charge (20) in said second combustion chamber (2) discharging to the outside via at least one vent (21). Characteristically, said first chamber (1) operates at high pressure and said second chamber (2) operates at low pressure. Another subject of the invention is a pyrotechnic gas generator suitable for the implementation of said method.The invention is most particularly applicable in the context of side protection airbags (“curtain airbags”), used in automobile safety.