945 results about "Sic fiber" patented technology

A fibrous silicon carbide substrate is disclosed that provides porosity through an open network of pores resulting from an intertangled arrangement of silicon carbide fibers. The fibrous structure is formed from mixing carbon or organic fibers with silicon based additives, and forming a honeycomb substrate. The carbon or organic fibers are heated in an inert environment to form silicon carbide through a reaction of the carbon in the fibers and the silicon-based additives.

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.

The invention discloses microwave absorbing ceramic of a silicon carbide compound material and a preparation method thereof. The microwave absorbing ceramic has a multifunctional layer laminated structure which comprises a matching layer, a depletion layer, a dielectric layer and a reflecting layer, wherein the matching layer, the depletion layer and the dielectric layer are respectively made of a continuous silicon carbide fiber reinforced silicon carbide-based compound material; the reflecting layer is made of a continuous carbon fiber reinforced silicon carbide-based compound material; andcontinuous silicon carbide fiber and continuous carbon fiber have different electrical resistivity. The preparation method comprises the flowing steps of: selecting a reinforced material; preparing asizing agent; preparing a rough blank; and preparing a finished product. The microwave absorbing ceramic has a wider absorbing frequency band, a higher mechanical property and a heat-resistant function.

The invention provides a composite core for a power grid transmission line wire and a preparation method thereof. The composite core has high strength, high toughness, high glass-transition temperature and surface cleanness. Materials of the composite core comprise a resin material and a strengthening material. The resin material comprises a thermosetting resin, a curing agent, an accelerating agent, a releasing agent, a flexibilizer and nanometer particles. The strengthening material is one kind or a plurality of kinds of carbon fiber, glass fiber, basalt fiber, boron fiber, aramid fiber, silicon carbonate fiber and protein bound iodine (PBI) fiber. The content of composite core fiber Vf=50-80%, tensile strength of the composite core is not lower than 2100MPa, and glass transition temperature of the composite core is not lower than 180 DEG C. The toughness of the composite core is remarkably improved, and breakage and cracking probability caused by brittleness factors in production, transportation and wire hanging construction processes are reduced.

The invention discloses a preparation method of a silicon carbide fiber reinforced silicon carbide composite material. The preparation method comprises the following steps of preparing a SiC fiber knitted piece, placing the SiC fiber knitted piece into a vacuum furnace to carry out chemical vapor deposition through adopting methane or propylene as feed gas and a pressure difference method to deposit a carbon coating on the surface of the SiC fiber knitted piece, carrying out a vacuum impregnation process on the SiC fiber knitted piece deposited with the carbon coating through adopting a liquid SiC ceramic precursor as impregnation liquid, putting the impregnated SiC fiber knitted piece into a mold, carrying out thermal molding crosslinking in a dynamic nitrogen atmosphere, putting the crosslinked SiC fiber knitted piece into a cracking furnace to carry out high temperature cracking in a dynamic nitrogen atmosphere, repeating a vacuum impregnation-thermal molding crosslinking-high temperature cracking cycle so as to finish preparation until the weight increment of a sample obtained after the vacuum impregnation-thermal molding crosslinking-high temperature cracking cycle is less than 1% of the weight increment of the sample obtained after the previous cycle. The preparation method has the advantages of short period, low cost, low pollution and toxic effects, etc.

The invention relates to a method for manufacturing silicon carbide fibre with high temperature resistance. Low molecular silane LPS is used as a raw material and has a reaction with an organic compound containing dense elements to synthesize AL, Y-containing polycarbosilane, namely PACS and PYCS; the PACS and PYCS are manufactured into continuous PACS and PYCS fibre by melt spinning; the PACS and PYCS fibre are subjected to infusible treatment to produce infusible fibre which can control the oxygen content; and the infusible fibre is calcinated and sintered at a high temperature under the protection of an inert atmosphere, thereby preparing SiC fibre with high crystallization and high temperature resistance. The method has the advantages of simple process, convenient operation, easy implementation by utilizing equipment for producing a common SiC fibre and low manufacturing cost; and a product produced by the method has the excellent characteristics of high strength, high temperature resistance, high oxidation resistance, etc. and is suitable for batch preparation in industry.

The disclosed preparation method for SiCf/SiC composite material comprises: selecting Polycarbosilane as predecessor and domestic continual silicon carbide fiber as reinforcement phase; preparing SiC coating on SiC fiber surface; then, preparing SiCf/SiC composite material with predecessor immersion and crack technique; finally, preparing an integral anti-oxidation coating on material surface. This invention needs only simple device and short production period.

The invention relates to a nuclear fuel cladding totally or partially made of a composite material with a ceramic matrix containing silicon carbide (SiC) fibers as a matrix reinforcement and an interphase layer provided between said matrix and said fibers, the matrix including at least one carbide selected from titanium carbide (TiC), zirconium carbide (ZrC), or ternary titanium silicon carbide (Ti₃SiC₂).

When irradiated and at temperatures of between 800° C. and 1200° C., said cladding can mechanically maintain the nuclear fuel within the cladding while enabling optimal thermal-energy transfer towards the coolant.

The invention also relates to a method for making the nuclear fuel cladding.

A SiCf/SiC ceramic-based composite material with composite interfaces is characterized by comprising CVD-SiC coating, a PIP-SiC matrix, the composite interfaces and SiC fiber, wherein the CVD-SiC coating is silicon carbide coating prepared through a chemical vapor deposition method, and has the thickness of 100-500 microns; the composite interfaces are formed by alternately and periodically overlapping any two or three of a BN interface, a ZrO2 interface, an LaPO4 interface and an SiC interface, and the cycle period frequency is 3-5 times; the PIP-SiC matrix is silicon carbide formed through in-situ pyrolysis of polycarbosilane; the SiC fiber accounts for 40-60% of the composite material by volume, a pyrolytic carbon layer with the thickness of 5-20 nanometers is formed on the surface thereof. A preparation method comprises the following steps: preparing multiple layers of composite interfaces on the surface of the silicon carbide fiber by different preparation processes, then fillingthe SiC matrix by a PIP method, and finally preparing the surface SiC coating by a CVD method. The SiCf/SiC ceramic-based composite material prepared through the preparation method provided by the invention is high in toughness and strong in antioxidant capacity, and the preparation process is simple.

The invention discloses a preparation method of a silicon carbide fiber with a boron nitride structure surface layer. The preparation method comprises the following steps of: 1, preparing a continuous polycarbosilane fiber through melt spinning; 2, carrying out melting-free treatment; and 3, nitriding for decarbonizing, and then sintering at high temperature. The preparation method has the advantages of simple process, convenience in implementation and low cost. The silicon carbide fiber with the boron nitride structure surface layer, prepared by the invention, has good properties of resisting high temperature and oxidization, is improved in fiber interface, and is enhanced in property of a fiber reinforced composite.

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.

The invention relates to a preparation method of silicon carbide fibers with a silicon nitride surface layer. The preparation method comprises the following steps of: using polycarbosilane (PCS) which is prepared by using organic silicon polymers through high-temperature cracking as raw materials, conducting melt-spinning to obtain continuous PCS polymer fibers, placing the continuous PCS polymerfibers in the atmosphere of air or activated gas for non-melting treatment, placing the non-melting fibers in a high-temperature atmosphere furnace for high-temperature nitration and decarbonization under the atmosphere of ammonia with certain concentration, and further sintering for densification at high temperature to obtain the silicon carbide fibers with the silicon nitride surface layer. Thepreparation method of the silicon carbide fibers with the silicon nitride surface layer has the advantages that the process and the equipment are simple, the cost of the prepared silicon carbide fibers is low and the resistivity is adjustable.

The method provides a method for in-situ growing carbon nanotubes on fiber surfaces, namely a method for directly growing carbon nanotubes on surfaces of fibers (carbon fibers, glass fibers, silicon carbide fibers, alumina fibers, high silica fibers, mullite fibers and the like). In the method, normal hexane, hexane, benzene, toluene, dimethylbenzene, ethanol or acetone is used as a carbon source, ferrocene is used as a catalyst, a sulfur compound such as sulfur, thiophene and the like are used as an accelerator, and hydrogen, argon, nitrogen, helium or the mixture of hydrogen, inert gas and the like is used as carrier gas, a horizontal reacting furnace device is used to direct grow the carbon nanotubes on the fiber surfaces under the conditions that the temperature ranges from 600 DEG C to 1000 DEG C and the carrier gas flow velocity is 10-2000ml/min. The method has the following advantage: the carbon nanotubes are directly grown on the fiber surfaces without depositing catalyst particles on the fiber surfaces in advance, which is beneficial to the large-scale growth of the carbon nanotubes on the surfaces of the fiber fabrics.

A novel polycrystalline stoichiometric fine SiC fiber substantially free of impurities is produced using a novel pre-ceramic polymer. The pre-ceramic polymer is prepared by reacting a mixture of chlorodisilane, boron trichloride, and a vinyl chlorodisilane with an excess of hexamethyldisilazane to form the pre-ceramic polymer resin, which may then be melt-spun, cured, pyrolyzed and heat-treated to obtain the finished SiC fiber. The manufacturing process for the production of the fine SiC ceramic fiber allows for flexibility with respect to cross-linking, in that low-cost thermal treatments may replace more complex methods, while obtaining fibers with improved materials properties as compared to currently available SiC fibers.

The production process of continuously preparing SiC fibre includes the following steps: dissolving high-molecular polymer in solvent to prepare skin solution, dissolving or dispersing the dispersingagent, high-molecular polymer, SiC powder and sintering adjuvant into solvent to prepare core solution, extruding skin solution and core solution from microhole of skin-core composite spinning component under the pressure to make skin solution cover exterior of the core solution, using wet process or dry process to solidifying fluid-flow wire, drawing, drying and winding so as to obtain raw fibre, its core portion is ceramic powder adhered by polymer and its skin portion is made of pure high-molecular material.

The invention provides a preparation method for high-temperature-resistance high-crystallized near-stoichiometric-ratio continuous SiC fiber. The preparation method comprises the steps: 1) enabling a polycarbosilane polymer to react with heterogeneous element compound to prepare a precursor and then spinning the precursor to obtain continuous fibril; 2) presintering and sintering the continuous fibril after the continuous fibril is treated in a non-melting mode to obtain the high-temperature-resistance high-crystallized near-stoichiometric-ratio continuous SiC fiber. According to the preparation method, heterogeneous elements are introduced into fiber in a precursor synthesizing process, and then boride is introduced into the fiber in non-melting or high-temperature presintering and sintering processes; a synergistic effect between the heterogeneous elements and the boride is utilized, so that SiC fiber crystal grains can rapidly grow under presintering and sintering high-temperature environment, meanwhile the SiC fiber is prevented from generating a loose and porous structure, and densification is achieved; thus, the dense high-crystallized near-stoichiometric-ratio continuous SiC fiber is obtained.

The invention discloses a SiCf/SiC ceramic-based composite material with a composite interface. The SiCf/SiC ceramic-based composite material with the composite interface has the characteristic of comprising a CVD-SiC coating, a PIP-SiC matrix, the composite interface and SiC fiber, wherein the CVD-SiC coating is a silicon carbide coating which is prepared by using a chemical vapor deposition method and has a thickness of 100-500 [mu]m, the composite interface is formed through alternate cyclic overlapping of arbitrary two or three of a BN interface, a ZrO2 interface, a LaPO4 interface and a SiC interface, and the cyclic number is 3-5 times; and the PIP-SiC matrix is silicon carbide formed through in-situ pyrolysis of polycarbosilane, the volume of the SiC fiber accounts for 40-60% of thevolume of the composite material, and a pyrolytic carbon layer of 5-20 nm thick is formed on the surface. The preparation method comprises the steps: preparing the multi-layer composite interface on the surface of the silicon carbide fiber by using different preparation processes, then filling a SiC matrix by using a PIP method, and finally preparing a surface SiC coating by using a CVD method. The prepared SiCf/SiC ceramic-based composite material has high toughness, high oxidation resistance and a simple preparation process.

The invention discloses a method for preparing an integral turbine blade disc based on a SiC fiber ceramic matrix composite material, which is used for solving the technical problem of the poor practicability of the existing integral turbine blade disc preparation method. The technical scheme is as follows. Firstly, a plane polar coordinate weaving method is adopted to prepare a turbine blade discprefabricated body unit layer, so that continuous SiC fibers are arranged in two principal stress directions in the warp direction and the weft direction. Then Z-direction puncture, sewing and die pressing are adopted to finish the shaping of the prefabricated body. A BN interface layer is prepared on the surface of the SiC fiber of the prefabricated body by utilizing a chemical vapor infiltration method. The prefabricated body of the turbine disc is pre-densified by adopting a chemical vapor infiltration process. The turbine disc blade is processed by adopting a cubic boron nitride or diamond special cutter on a multi-axis numerical control machine tool. Finally, an anti-oxidation coating is prepared. As the prefabricated body is provided with the continuous SiC fibers in two main principal directions in the warp direction and the weft direction, the bearing performance of the integral turbine blade disc is improved, the preparation period of the integral turbine blade disc is shortened, and the practicability is good.

In various embodiments, composite materials containing a ceramic matrix and a carbon nanotube-infused fiber material are described herein. Illustrative ceramic matrices include, for example, binary, ternary and quaternary metal or non-metal borides, oxides, nitrides and carbides. The ceramic matrix can also be a cement. The fiber materials can be continuous or chopped fibers and include, for example, glass fibers, carbon fibers, metal fibers, ceramic fibers, organic fibers, silicon carbide fibers, boron carbide fibers, silicon nitride fibers and aluminum oxide fibers. The composite materials can further include a passivation layer overcoating at least the carbon nanotube-infused fiber material and, optionally, the plurality of carbon nanotubes. The fiber material can be distributed uniformly, non-uniformly or in a gradient manner in the ceramic matrix. Non-uniform distributions may be used to form impart different mechanical, electrical or thermal properties to different regions of the ceramic matrix.

The invention relates to an in-situ growth SiC nanowire reinforced SiC ceramic matrix composite material. The in-situ growth SiC nanowire reinforced SiC ceramic matrix composite material consists of areinforced fiber, SiC nanowires, an interface layer and an SiC matrix, and is characterized in that the SiC nanowires are grown on the reinforced fiber in an in-situ manner; the surface of the reinforced fiber and the surfaces of the SiC nanowires are coated with the interface layer; the SiC matrix is filled in a gap surrounded by the reinforced fiber and the SiC nanowires; the reinforced fiber is C fiber or SiC fiber; the diameters of the SiC nanowires are 50 to 200 nm, and the lengths of the SiC nanowires are 0.5 to 3 mm; the interface layer is PyC or BN, and the thickness of the interfacelayer is 0.02 to 0.1 micron. The in-situ growth SiC nanowire reinforced SiC ceramic matrix composite material effectively solves the problem that the SiC nanowires are relatively difficult to distribute uniformly in a fiber perform, and in addition the advantage of the SiC nanowires for the SiC ceramic matrix composite material is sufficiently developed through the in-situ growth SiC nanowires.