543 results about "Chemical vapor infiltration" patented technology

In the present embodiment, in the production of a heat-resistant composite material resulting from impregnating a ceramic fiber preform with silicon carbide, a mixed gas containing starting material gas, an additive gas, and a carrier gas is supplied to a substrate having a minute structure such as a preform stored in an electric furnace, silicon carbide is deposited to form a film by means of a chemical vapor deposition method or a chemical vapor infiltration method, and the film formation growth speed and embedding uniformity are controlled by means of the amount of additive gas added to the starting material gas, the starting material gas contains tetramethylsilane, and the additive gas contains a molecule containing chlorine such as methyl chloride or hydrogen chloride. The film formation growth speed and embedding uniformity of the silicon carbide are both achieved.

A method of densifying a porous substrate with a matrix, includes subdividing the pores present in the porous substrate so as to form in the substrate a network of micropores, the subdividing being performed with a filler composition comprising at least one carbon-containing phase or carbide-containing phase that is accessible via the network of micropores; and infiltrating the network of micropores formed by the filler material by reactive chemical vapor infiltration, the infiltration being performed with a reactive gas composition that does not contain carbon and that includes at least one element suitable for reacting with the carbon of the filler composition in order to form a carbide.

This invention relates to preparation method gas phase siliconizing technique preparing high compact fiber reinforcement SiC group composite material. Protection layer interface is formed on fiber surface through gas phase or liquid phase, then they are dipped and cracked through nm SiC slime to make certain density precast body of fiber reinforcement SiC group. Carbon is added into the body through dipping and cracking way to form group body with certain pore, the group body penetrates inner part of the multi-hole body through gas phase silicon after it is high temperature treated, then it reacts with carbon and fills the pore to get compact basal body. The density of the material can reach 2.25-2.30g / cm3, open porosity is 3-6 percent; it is large more higher than traditional method of getting Cf / SiC material.

The invention relates to a carbon fiber reinforced boron carbide composite material and a preparation method thereof. The preparation method comprises the following steps of: preparing a carbon fiber preform by adopting a needling, puncturing or three-dimensional weaving process; and depositing boron carbide matrix in the porous carbon fiber preform by osmosis to form the compact carbon fiber reinforced boron carbide composite material. Aiming at a certain specific application environment, a boron carbide coat can be deposited on the surface of a sample by adopting the same chemical vapor osmosis process. The carbon fiber reinforced boron carbide-based composite material manufactured by the method has the characteristics of good mechanical property, toughness superior to that of the traditional sintered boron carbide, compact structure, light weight, abrasion resistance and high hardness, and is suitable to be applied to a high-temperature light structural component.

A process for producing a silicon-containing CMC article. The process entails depositing one or more coating layers on silicon carbide (SiC) fibers, drawing the coated SiC fibers through a slurry to produce slurry-coated fiber material, and then processing the slurry-coated SiC fiber material to form unidirectional prepreg tapes. The tapes are stacked and then fired to yield a porous preform. The porous preform is then further densified by infiltrating the porosity therein to yield a CMC article. Infiltration can be achieved by a series of polymer infiltration and pyrolysis (PIP) steps, by melt infiltration (MI) after filling the porosity in the preform with carbon or one or more refractory metal, by chemical vapor infiltration (CVI), or by a combination of these infiltration techniques.

A crystal whisker and particle toughened ceramic-based composition used to make large thin-wall member is prepared through granulating to prepare the coagulated substance of crystal whiskers and particles, preparing the prefabricated body of crystal whisker-particle reinforcing body, and depositing the ceramic base in said prefabricated body by chemical vapour osmosis process.

A thermal treatment process for improving thermo-mechanical properties of ceramic matrix composite materials such as silicon carbide (SiC) matrix composites is described. The treatment process removes excess silicon and / or other process-related defects from the SiC-based matrix as well as the fiber interfacial coating. This invention can be practiced with minimal strength loss for as-fabricated composites formed from high-strength continuous-length ceramic and carbon-based fibers that are functionally stable to 1600° C. and above. The invention provides a method for significantly improving composite thermal conductivity and creep resistance, and for reducing composite porosity. It has been demonstrated using state-of-the-art 2D woven SiC / SiC composites containing Sylramic-iBN SiC fibers, boron-nitride-based interfacial coatings, and hybrid matrices that are based on SIC formed by chemical vapor infiltration (CVI) and by a combination of CNI, SiC particulate infiltration, polymer infiltration and pyrolysis, and melt infiltration of silicon, silicon-based alloys, and silicides.

A method of fabricating a complex part out of composite material including three-dimensional woven fiber reinforcement densified by a matrix, the method including three-dimensionally weaving a continuous fiber strip including a succession of fiber blanks for preforms of a plurality of parts that are to be fabricated; subsequently cutting individual fiber blanks out from the strip, each blank being a one-piece blank; shaping a cut-out blank to obtain a one-piece fiber preform having a shape that is close to the shape of a part that is to be fabricated; consolidating the preform in the desired shape; and densifying the consolidated preform by forming a matrix by chemical vapor infiltration.

The invention relates to a method for manufacturing a self-healing silicon carbide ceramic matrix composite. The method comprises the following steps: preparing fiber preform; filtrating a pyrolytic carbon interface layer by chemical gas phase; carrying out thermal treatment on the interface layer; infiltrating silicon carbide and boron carbide substrate by chemical gas phase alternately; and depositing three silicon carbide coatings by the chemical gas phase. The method has strong designability, simple process and good repeatability. The ceramic matrix composite manufactured by the method has good high temperature resistance and oxidation resistance, has excellent mechanical performance and thermal performance, and can meet the use requirement of a sealing strip / an adjustment sheet, an interior cone and other components of a high thrust-weight ratio aeroengine.

The invention discloses a method for preparing a carbon / carbon-silicon carbide composite material for bearings. The preparation method comprises the following steps: preparing a carbon fiber integral felt of 0.15-0.30g / cm<3> from polyacrylonitrile preoxidized fibers through puncture carbonization, or preparing a non-woven cloth carbon fiber integral felt of 0.4-0.6g / cm<3> from non-woven cloth and a mesh tyre through puncture carbonization in an alternating lamination manner; preparing C / C porous preform with density of 1.35-1.75g / cm<3> by adopting a chemical vapor infiltration (CVI) and resin precursor infiltration and pyrolysis (PIP) comprehensive process, and performing a high-temperature treatment at 2,250-2,600 DEG C in the Ar gas protective atmosphere; and vacuumizing, then introducing Ar gas, heating to 2,200-2,350 DEG C to perform liquid silicon infiltration, and preserving heat for 1.5 hours. The method is a preparation method of the carbon / carbon-silicon carbide (C / C-SiC) composite material with little residual silicon and low abrasion rate for bearings.

A liquid composition is applied onto the surface of the part to be treated, the composition containing a ceramic precursor polymer and a refractory solid filler. After cross-linking, the polymer is transformed into ceramic by heat treatment, and subsequently ceramic is deposited by chemical vapor infiltration. Before the chemical vapor infiltration step, the surface of the part is shaved so as to return the composite part to its initial shape so that the chemical vapor infiltration forms a deposit that fills in the residual micropores in the shaved surface of the part.

The invention discloses novel liquid polycarbosilane which is low in viscosity and high in storage stability and is crosslinkable, a preparation method of novel liquid polycarbosilane, and an application of novel liquid polycarbosilane. Polycarbosilane is prepared by adopting chloromethyl alkoxy silane or mixtures of chloromethyl alkoxy silane as raw materials by virtue of Grignard coupling reaction and reduction reaction, and the structure of polycarbosilane is shown in a formula (I) in the specification. The structure simultaneously contains Si-H bonds and unsaturated bonds such as C=C bonds, can be subjected to self-crosslinking and curing under a certain condition, has relatively high ceramic yield, and can be used as a silicon carbide precursor of a polymer precursor impregnation pyrolysis (PIP) process. Polycarbosilane disclosed by the invention is adjustable in structural composition, good in storage stability, low in viscosity and relatively low in boiling point, and has the utilization potentiality of being used as a silicon carbide ceramic precursor for chemical vapor deposition / chemical vapor infiltration (CVD / CVI). In addition, polycarbosilane can also be used for replacing commonly-used divinyl benzene to serve as a crosslinking agent of solid-state polycarbosilane (PCS).

To densify thin porous substrates (1) by chemical vapor infiltration, the invention proposes using loading tooling (10) comprising a tubular duct (10) disposed between first and second plates (12, 13) and around which the thin substrates for densification are disposed radially. The tooling as loaded in this way is then placed inside a reaction chamber (20) in an infiltration oven having a reactive gas admission inlet (21) connected to the tubular duct (11) to enable a reactive gas to be admitted into the duct which distributes the gas along the main faces on the substrates (1) in a flow direction that is essentially radial. The reactive gas can also flow in the opposite direction, i.e. it can be admitted into the tooling (10) from its outer envelope (16) and can be removed via the duct (11).

The present invention relates to a method of producing carbon fiber reinforced ceramic matrix composites, the method of producing carbon fiber reinforced ceramic matrix composites according to the present invention is characterized in that the method comprises the steps of: producing a carbon fiber reinforced resin composite that is molded with a mixture in which carbon fibers and polymer precursors containing carbon are mixed; producing a carbon fiber reinforced carbon composite by depositing pyrolytic carbon during a rapid thermal gradient chemical vapor infiltration process while increasing the deposition speed in a direction from the inside to the outside by performing a thermal treatment on said carbon fiber reinforced resin composite at high temperature; and infiltrating liquid-phase silicon into the pores of said carbon fiber reinforced carbon composite. The method of producing carbon fiber reinforced ceramic matrix composites according to the present invention as described above has the effect of improving the properties of carbon fiber reinforced ceramic matrix composites, and it is possible to deposit a pyrolytic carbon layer at a deposition speed 5-10 times faster than other conventional chemical vapor infiltration processes, thereby showing a remarkably improved effect in terms of manufacturing process, time, and cost.

A carbon-carbon composite for friction products comprises an outer friction part and a load bearing structure part supporting the friction part. The friction part contains a mixture of carbon fibers, pitch powder and graphite powder, whereas the structure part is comprised of a pack of alternating layers of the mixture and layers of one member selected from the group consisting of carbon fabrics, carbon-based prepregs and carbon-based, segmented prepregs. The carbon-carbon composite is formed by way of aternatingly piling up layers of a mixture of carbon fibers, pitch powder and graphite powder and layers of one member selected from the group consisting of carbon fabrics, carbon-based prepregs and carbon-based, segmented prepregs one above the other to provide a preform, heating and pressing the preform within a mold to obtain a green body, carbonizing the green body to prepare a carbonized body, impregnating the carbonized body with pitch powder and recarbonizing the impregnated body, and subjecting the impregnated and recarbonized body to chemical vapor infiltration with hydrocarbon gas.

Annular substrates (20) are stacked in an enclosure where they define an inside volume (24) and an outer volume (26) outside the stack. A gas containing at least one precursor of a matrix material to be deposited within the pores of the substrates is channeled inside the enclosure to a first one (24) of the two volumes, and a residual gas is extracted from the enclosure from the other one (26) of the volumes. One or more leakage passages (22) allow the volumes to communicate with each other, other than through the substrates. The total section of the leakage passages has a value lying between a minimum value for ensuring that a maximum gas pressure in the first volume is not exceeded until the end of densification, and a maximum value such that a pressure difference is indeed established between the two volumes from the beginning of densification.

The invention relates to a preparation method for a carbon / carbon-copper composite material, which belongs to the technical field of special carbon fiber composite materials. The preparation method mainly comprises the following preparation processes: preparation of carbon fiber green bodies; preparation of carbon / carbon preforms; and preparation of the carbon / carbon-copper composite material. The preparation processes comprise the following steps: firstly, cross-linking fibers in a pre-oxidized fiber felt of polyacrylonitrile by using needle-punching; secondly, performing carbonization on the needle-punched pre-oxidized fiber felt to form a carbon fiber needle-punched felt; thirdly, depositing pyrolytic carbon on the surfaces of the carbon fibers by using a chemical vapor infiltration (CVI) process, or densifying the carbon fibers by using a process combining the CVI process and resin impregnation, wherein the carbon fibers are adhered together through the pyrolytic carbon or the pyrolytic carbon and resin carbon to form a porous carbon / carbon composite material preform; and fourthly, performing high-temperature treatment on the porous carbon / carbon composite material preform, and impregnating the solution of copper into the carbon / carbon composite material preform by using a gas pressure infiltration method to obtain the carbon / carbon-copper composite material finally.

A method of manufacturing a turbine engine component is disclosed. The method includes the steps of providing a plurality of ceramic cloth plies, each ply having woven ceramic fiber tows and at least one fugitive fiber tow, laying up the plurality of plies in a preselected arrangement to form a turbine engine component shape, oxidizing the fugitive fibers to produce fugitive fiber void regions in the ply, rigidizing the component shape to form a coated component preform using chemical vapor infiltration, partially densifying the coated component preform using carbon-containing slurry, and further densifying the coated component preform with at least silicon to form a ceramic matrix composite turbine engine component having matrix rich regions.

The invention discloses a method for manufacturing carbon / ceramic braking linings used in an industrial brake, which comprises the following steps: carbon fiber performs are prepared by a needle method; low-density C / C composite material is prepared by a chemical gas permeation method after the carbon fiber performs are treated in high temperature; the C / C composite material is treated in high temperature, machined and then the molten silicon infiltration is carried out on the C / C material in a high temperature vacuum furnace; Sic is formed by the Si and C reaction to prepare C / C-SiC baking material; and finally after the C / C-SiC baking material is machined, the C / C-SiC baking material is riveted with the steel backing by a rivet in a cold way to prepare the needed C / C-SiC baking material used in an industrial brake. The carbon / ceramic braking lining manufactured by the method has higher mechanical property and excellent frictional wear performance and is used in the industrial brake.

The invention relates to a rapid preparation method for a C / SiC composite material. The method is characterized by including the steps of: 1. depositing a pyrolytic carbon interface on a thin layer carbon fiber preform surface by a chemical vapor deposition process; 2. infiltrating the thin layer carbon fiber perform of the deposited PyC interface in a polycarbosilane mixed solution, and then carrying out cross-linking curing and pyrolysis in order under protective atmosphere to obtain a thin layer C / SiC composite material; 3. repeating the previous step 2-3 times; and 4. stacking a plurality of single-layer composite materials in a graphite die to conduct spark plasma sintering (SPS), thus rapidly obtaining a compact C / SiC composite material finally. The method provided by the invention makes full use of the characteristics of short thin layer infiltration time of PIP (precursor infiltration and pyrolysis) method and rapid sintering of SPS method to realize preparation of the C / SiC composite material, is suitable for compaction of small compact components, saves 95% of time than the traditional CVI (chemical vapor infiltration) method and PIP method, also significantly improves the compactness of the composite material, and reduces the making cost of the composite material.

A preparation method of a three-dimensional needling carbon / carborundum composite material bolt adopts a three-dimensional needling fiber prefabrication body to prepare the composite material bolt. Pyrolytic carbon is deposited on the prefabrication body, carborundum substrates are deposited through chemical vapor infiltration (CVI), and a bolt bar blank and a bolt cap blank are obtained. The carborundum substrates of the bolt bar blank and the bolt cap blank which are obtained through machining are deposited through the CVI, a carborundum anti-oxidation coating is deposited through the CVI, and a three-dimensional needling C / SiC composite material bolt end product with the shear strength being 80-100MP is obtained. Compared with the prior art, the preparation method has the advantages that the number of times for getting into a furnace is reduced by 6-10, the densifying period is shorter, and the production cost is reduced. By means of a test of a CK6180-3000 numerically controlled lathe, the preparation method is small in diamond grinding wheel abrasion, hour norm for machining 30 bolt threads is reduced by about 10 hours, and as the abrasion of a grinding wheel is less, the working accuracy is improved, and industrialized batch production is achieved.

The invention discloses a C-C-SiC-ZrC ceramic matrix composite and a preparation method thereof. The C-C-SiC-ZrC ceramic matrix composite comprises C fiber, a C matrix, an SiC matrix and a ZrC matrix, and is characterized in that the SiC matrix exists between a C / C framework and the ZrC matrix. The preparation method comprises the steps as follows: the C fiber is woven or laminated to form an enhancement structure, pyrolytic carbon is deposited with a chemical vapor infiltration method, then the synthesized C / C framework is subjected to high-temperature graphitization, an SiC densified composite is introduced through liquid-phase infiltration and pyrolysis of polycarbosilane, boron-containing phenolic resin is soaked, C is formed through pyrolysis, metal Zr is infiltrated with an infiltration method, and high-temperature heat treatment is performed to obtain the C-C-SiC-ZrC ceramic matrix composite. The C-C-SiC-ZrC ceramic matrix composite has excellent performance including high strength, superhigh temperature resistance, antioxidation, thermal shock resistance and the like.

The invention belongs to the field of composite material manufacture, and relates to a method for manufacturing SiC / SiC composite material pin with a precursor infiltration and pyrolysis method. The method is characterized in that firstly, a 1K SiC fiber bundle is taken as a raw material; a fiber prefabricate of the pin is manufactured by adopting a 2D weaving mode; the pin fiber prefabricate is placed in a graphite mould for moulding, and then an interface layer is manufactured through chemical vapor infiltration (CVI); a base body is manufactured through precursor infiltration and pyrolysis (PIP), so that the SiC / SiC composite material pin is manufactured; and the manufactured SiC / SiC composite material pin is high in strength and good in tenacity. Compared with an original two-dimensional stacking structure composite material pin, the SiC / SiC composite material pin has the advantages that no layering problem exists; and before being manufactured into the pin, the two-dimensional stacking structure composite material needs to be cut and manufactured into long-strip-shaped firstly, and then is subjected to pin moulding manufacture, so that layering and performance lowering of the composite material are easily caused, and the two-dimensional stacking structure composite material pin is high in manufacture cost and low in efficiency. According to the method, the manufacture efficiency and mechanical performance stability of the pin are improved, and the method has a wide market promotion and application prospect.

Methods for manufacturing porous nuclear fuel elements for use in advanced high temperature gas-cooled nuclear reactors (HTGR's). Advanced uranium bi-carbide, uranium tri-carbide and uranium carbonitride nuclear fuels can be used. These fuels have high melting temperatures, high thermal conductivity, and high resistance to erosion by hot hydrogen gas. Tri-carbide fuels, such as (U,Zr,Nb)C, can be fabricated using chemical vapor infiltration (CVI) to simultaneously deposit each of the three separate carbides, e.g., UC, ZrC, and NbC in a single CVI step. By using CVI, a thin coating of nuclear fuel may be deposited inside of a highly porous skeletal structure made, for example, of reticulated vitreous carbon foam.

A composite material part is made by forming a fiber preform (20), forming holes (22) extending within the preform from at least one face thereof, and densifying the preform with a matrix formed at least in part by a chemical vapor infiltration (CVI) type process. The holes (22) are formed by removing material from the preform with fibers being ruptured, for example by machining using a jet of water under pressure, the arrangement of the fibers in the preform with the holes being substantially unchanged compared with the initial arrangement before the holes were formed. This enables the densification gradient to be greatly reduced, and it is possible in a single densification cycle to obtain a density that, in the prior art, required a plurality of cycles separated by intermediate scalping.

The invention relates to a chemical vapor deposition method of a Si-B-C-N amorphous ceramic. The chemical vapor deposition method comprises the following steps of: suspending a substrate material on a matching sample bracket of a vacuum furnace, putting samples in a centre of an isothermal region in the furnace and preparing even Si-B-C-N amorphous ceramic on the surface / interior of the substrate material by using a CVD (Chemical Vapor Deposition) / CVI (Chemical Vapor Infiltration) method. The Si-B-C-N amorphous ceramic prepared by the chemical vapor deposition method can be applied to an interface, a matrix and a coating of a continuous fiber-reinforced ceramic matrix composite, has the advantages of excellent properties such as good high-temperature stability, good anti-oxidation property, strong creep resisting capability, low density, low coefficient of thermal expansion and low heat conductivity coefficient and the like, can replace materials such as SiC and Si3N4, further improves the using temperatures and prolongs the service lives of thermal structure ceramics and ceramic matrix composites and has a great application potentiality in the isothermal and long-life field of aircraft engines and industrial gas turbines; and meanwhile, the Si-B-C-N amorphous ceramic also has electrical properties similar to the semiconductors and interesting optical properties and is widely used in the fields of high-temperature invisibility, semiconductors, photoelectricity, communication and control.

Annular substrates (20) are stacked in an enclosure where they define an inside volume (24) and an outer volume (26) outside the stack. A gas containing at least one precursor of a matrix material to be deposited within the pores of the substrates is channeled inside the enclosure to a first one (24) of the two volumes, and a residual gas is extracted from the enclosure from the other one (26) of the volumes. One or more leakage passages (22) allow the volumes to communicate with each other, other than through the substrates. The total section of the leakage passages has a value lying between a minimum value for ensuring that a maximum gas pressure in the first volume is not exceeded until the end of densification, and a maximum value such that a pressure difference is indeed established between the two volumes from the beginning of densification.

The present invention generally relates to a woven preform for reinforced composite materials and a method of making thereof. Specifically, the present invention is a method of machine weaving fiber preforms for polymer matrix composites that consist of closed perimeters with multiple intersecting members in their interiors. More specifically, the invention is a woven preform and a method of forming thereof with closed cells at the outer edges with continuous hoop reinforcement in each cell of the preform. The woven preform is woven flat in both the warp and weft directions, and then unfolded to achieve the final shape of the structure, and can be processed into composite structural components using known methods such as resin transfer molding or chemical vapor infiltration. Thus, complicated shapes of all sizes can be woven on a conventional loom using the instant method.

A method of densifying porous substrates by chemical vapor infiltration comprises loading porous substrates for densification in a loading zone of an enclosure (10), heating the internal volume of the enclosure, and introducing a reagent gas into the enclosure though an inlet situated at one end of the enclosure. Before coming into contact with substrates (20) situated in the loading zone, the reagent gas admitted into the enclosure is preheated, at least in part, by passing along a duct (30) connected to the gas inlet and extending through the loading zone, the duct being raised to the temperature inside the enclosure, and the preheated reagent gas is distributed in the loading zone through one or more openings (33) formed in the side wall (32) of the duct, along the duct.

The invention discloses a carbon / carbon / silicon carbide composite material with a simple preparation technology and silicon steam corrosion resistance, and a preparation method. The carbon / carbon / silicon carbide composite material is characterized by being prepared by a process that a carbon fiber prefabricated body is machined and purified after being subjected to pyrolytic carbon and silicon carbide alternating densification or pyrolytic carbon and silicon carbide mixing densification with a chemical vapor infiltration method. The density of the carbon / carbon / silicon carbide composite material is 1.3-2.5g.cm<3>, the flexural strength is more than or equal to 300MPa, and the fracture toughness is more than or equal to 15MPa.m<1 / 2>. According to the carbon / carbon / silicon carbide composite material disclosed by the invention, corrosion on the core part carbon fiber of the carbon / carbon / silicon carbide composite material by silicon steam can be effectively inhibited. The flexural strength of the prepared carbon / carbon / silicon carbide composite material is more than 300MPa which is 2-5 times of that of carbon / carbon composite material, the fracture toughness is more than or equal to 15MPa.m<1 / 2>, the silicon steam corrosion resistance capability is improved by 5-10 times in comparison with that of the carbon / carbon composite material, and the service life of the carbon / carbon / silicon carbide composite material is drastically prolonged. Meanwhile, the higher strength of the carbon / carbon / silicon carbide composite material is favorable for improving the safety of a thermal field.