21 results about "Porous sic" patented technology

This invention belongs to the field of ceramic composite material manufacturing technology, specifically relating to a method for preparing SiC composite materials based on cold spraying and silicon infiltration. SiC powder is prepared into a suspension, which is then deposited onto a substrate using a cold gas-powered spraying system to form a porous SiC preform coating. The preform coating undergoes post-curing to enhance its cohesive strength. Finally, melt silicon infiltration is performed, causing silicon to react with carbon in the preform to generate a new SiC phase that fills the pores, resulting in a high-density, high-performance SiC composite component. This method combines the advantages of low-temperature forming in cold spraying with silicon infiltration technology. The relatively low substrate temperature during cold spraying effectively avoids the adverse effects of high temperatures on the material structure, maintaining the stability of the original SiC phase. By adjusting the spraying parameters and matching the silicon infiltration process, the free silicon content and the distribution of the newly generated SiC phase in the composite material can be precisely controlled, further improving the material's density and mechanical properties.

The invention relates to the field of superconducting material preparation, and discloses a method for preparing an MgB2-MgB2 superconducting joint through hot pressed sintering, which comprises the following steps: preparing metal magnesium powder and nano boron powder subjected to surface coating treatment into an intermediate connecting agent according to a ratio, and filling a joint area between superconducting wires with the intermediate connecting agent; and hot pressing sintering treatment is carried out under the controlled atmosphere, and a continuous and compact MgB2 phase connection structure is formed. In order to improve the interface bonding quality and oxidation resistance, a porous SiC transition layer can be introduced into the joint interface in advance, and staged atmosphere control is adopted to achieve grain boundary purification and regulation. The method is simple in operation process, low in joint resistance and high in shear strength, has excellent thermal stability and electrochemical stability, and is suitable for actual connection application of high-performance superconducting devices.

The invention relates to the technical field of ceramic / metal heterogeneous material connection, in particular to a method for low-temperature brazing of a porous SiC / TC4 connecting piece based on ultrasonic-assisted pre-dip plating. In order to solve the problems that in the prior art, a porous SiC ceramic structure is prone to damage, and the mechanical property of a connecting piece is low, the method comprises the two steps that firstly, low-temperature brazing filler metal is pre-dip-plated on the surface of porous SiC and TC4 alloy under ultrasonic assistance, the brazing filler metal is promoted to permeate into ceramic pores through the acoustic capillary effect, a bonding layer is formed, the ultrasonic effect is indirectly applied, and the bonding layer is formed; the ceramic matrix is prevented from being damaged; and then, the pre-dip-plated component is subjected to brazing connection at low temperature, and a compact and reliable connector is formed. According to the method, high-strength and low-damage connection of the porous ceramic and the titanium alloy at the low temperature is achieved, the process is simple and convenient, and the method is suitable for preparing complex structural parts in the fields of aerospace, chemical filtration and the like.

The invention provides a brazing method for modified porous SiC ceramic and 2507 duplex stainless steel, and belongs to the technical field of welding. The brazing method comprises the following steps that silicon carbide suspension slurry is prepared; adhering the silicon carbide suspension slurry to the surface of the porous SiC ceramic, drying, discharging glue, and sintering to obtain the modified porous SiC ceramic; and after the surface of the pretreated porous SiC ceramic is polished, 2507 duplex stainless steel, the high-entropy alloy brazing filler metal and the modified porous SiC ceramic are stacked from top to bottom, vacuum brazing is carried out, and natural cooling is carried out at the room temperature after the reaction is finished. According to the method, the porous SiC ceramic surface with poor welding performance is subjected to densification modification treatment, the high-entropy alloy brazing filler metal is good in fluidity and can be well combined with the densified surface layer, the residual stress of the porous ceramic and a metal reaction layer is reduced, and the porous ceramic and metal can form the compact reaction layer with a stable structure under the action of the brazing filler metal.

The invention relates to a method for obtaining at least one ceramic component by joining at least two SiC preforms:-providing at least two porous SiC preforms, such as a green part or a coked part, each having at least one joining surface; providing a bonding slurry comprising-40 to 80 wt.%, preferably 50 to 70 wt.%, of at least one binder,-2 to 20 wt.%, preferably 5 to 18 wt.%, more preferably 8 to 15 wt.%, of silicon carbide particles having a particle size D50 of 10 to 20 [mu] m, preferably 11 to 18 [mu] m, more preferably 11 to 16 [mu] m; -8 to 25 wt%, preferably 9 to 20 wt%, more preferably 10 to 15 wt% of silicon carbide particles having a particle size D50 of 1 to 10 [mu] m, preferably D50 of 2 to 8 [mu] m, more preferably D50 of 2 to 5 [mu] m,-10 to 30 wt%, preferably 12 to 20 wt%, more preferably 13 to 18 wt% of carbon black, -wherein the sum of all the ingredients always totals 100% by weight; -pressing the joining surfaces of the at least two SiC preforms together; -drying the at least two SiC preforms; and-heating the at least two SiC preforms, whereby Si permeates into the SiC preform comprising the dried bonding slurry, thereby obtaining a substantially bonded silicon-silicon carbide (SiSiC) ceramic component.

This invention discloses Y 0.4 Sr 0.6 This invention relates to porous MnO3 perovskite supported materials, their synthesis method, and applications, belonging to the field of catalyst materials for CO2 fuel synthesis through cracking. The invention aims to solve the problems of low stability, low CO yield, and low CO2 conversion rate of catalytic materials in the two-step CO2 catalytic cracking process of solar thermochemical fuel preparation. The method involves mixing EDTA with an ammonia solution, adding deionized water, heating in a water bath, and magnetically stirring. Y(NO3)3·6H2O, Mn(NO3)2·4H2O, and Sr(NO3)2 powder are added, followed by citric acid monohydrate. Ammonia is added to adjust the pH value, while maintaining heating and stirring. The mixture is dried, ground, calcined, and then ground again. It is then mixed with deionized water, and the suspension is dropwise applied to a porous SiC framework and purged. The mixture is then dried. This invention utilizes Y... 0.4 Sr 0.6 The MnO3 powder material adheres to the porous SiC framework, which enhances the gas-solid reaction contact area between the powder material and CO2, thereby increasing the redox reaction rate. The heating rate of the material is accelerated, and the photothermal conversion efficiency and overall efficiency are improved.

The invention belongs to the technical field of ceramic composite material manufacturing, and particularly relates to a SiC composite material preparation method based on cold spraying and siliconizing, which comprises the following steps: preparing SiC powder into suspension liquid, and depositing the suspension liquid on a substrate by using a cold air power spraying system to form a porous SiC preform coating; performing post-curing treatment on the prefabricated body coating to improve the cohesive strength of the prefabricated body coating; and finally, through melt siliconizing treatment, silicon reacts with carbon in the prefabricated body to generate a new SiC phase, pores are filled with the new SiC phase, and the SiC composite material component with high density and excellent performance is obtained. The advantage of low-temperature forming of low cold spraying is combined with the siliconizing technology, the temperature of a matrix is low in the cold spraying process, the adverse effect of high temperature on the material structure is effectively avoided, and the stability of the original phase of SiC is kept. And by regulating and controlling spraying parameters to be matched with a siliconizing process, the content of free silicon in the composite material and the distribution state of a newly generated SiC phase can be accurately controlled, and the compactness and the mechanical property of the material are further improved.

The invention relates to the technical field of 3D printing, and particularly discloses a preparation method of a fiber-reinforced porous SiC ceramic sandwich structure. The DIW technology is used for achieving one-time forming of the component with the complex three-dimensional structure, a mold does not need to be prepared in advance, the prepared ceramic component does not need to be subjected to follow-up machining, and the preparation cost is low. After the blank is printed, densification can be completed only through one-time sintering, and a complex post-treatment process is not needed. The shrinkage rate of the core material and the shrinkage rate of the panel material can be matched with each other by adjusting the proportion of the PMMA to the carbon fiber of the core slurry, so that the damage of the interface between the panel layer and the core layer caused by mismatching of the shrinkage rates in the sintering process is reduced, and the mechanical strength of the sandwich structure is improved. The thickness of the panel and the core of the sandwich structure can be flexibly and conveniently adjusted through the DIW technology, and therefore differential regulation and control over the functionality or the mechanical property of the sandwich structure are achieved.

The invention provides a microreactor for electrochemically synthesizing ammonia, the microreactor comprises a membrane electrode assembly and two flow field plates, the membrane electrode assembly comprises a flaky cathode, an anode and a proton exchange membrane, the cathode comprises a substrate and a nitrogen reduction electrocatalyst, and the substrate is a silicon carbide-hexagonal boron nitride composite ceramic material with a porous structure. The electrochemical ammonia synthesis system further comprises a gas supply unit, an electrolyte circulating unit, a power supply, a detection unit, a product separation unit and an intelligent control unit. The invention further provides an electrochemical ammonia synthesis method which comprises the steps of system preparation and activation, continuous reaction process, online monitoring and optimal control, product collection and the like. The porous SiC-BN composite ceramic is used as a cathode substrate material, so that the reaction efficiency is greatly improved, and meanwhile, the transmission rate of reactants and products is also improved. The gas-liquid-solid three-phase reaction interface in the membrane electrode assembly is greatly improved, and the stability of the membrane electrode assembly under the microscopic condition is also greatly enhanced.

This invention discloses a method for low-temperature preparation of water-resistant, oxygen-resistant bulk modified SiC with boron-containing mesophase assistance. f This paper relates to the field of composite materials technology, specifically SiC composite materials, their preparation methods, and applications. The method includes the preparation of porous SiC... f / SiC composite material; obtain boron-containing resin precursor solution; porous SiC f After immersing the SiC composite material in a boron-containing resin precursor solution, a cured composite is obtained. The cured composite is then held at 900–1100℃ for 2–4 hours to obtain a pyrolysis composite. This pyrolysis composite is then coated with Y-Si powder and further wrapped with graphite paper. Finally, it undergoes a reaction melt infiltration process under vacuum at 1260–1300℃ for 10–30 minutes to obtain water-resistant, oxygen-modified SiC. f / SiC composite materials. This invention utilizes mesophase-assisted preparation of modified SiC. f / SiC composite materials, on the one hand, reduce the preparation temperature and reduce fiber damage; on the other hand, they avoid the premature appearance of the low-temperature Y-Si phase and improve the ultimate service temperature of the composite material.

The invention discloses an AlSiC high-thermal-conductivity packaging material based on a photovoltaic silicon sludge in-situ synthesized porous SiC skeleton and a preparation method of the AlSiC high-thermal-conductivity packaging material, and belongs to the field of industrial solid waste high-valued utilization. The preparation method comprises the following steps: adding a metal / aluminum oxide bonding layer precursor, mixing with silicon mud powder, carbon source powder, a bonding agent and a pore forming agent, granulating, forming, and treating by a variable atmosphere gradient high-temperature sintering process to synthesize a 6H-SiC porous skeleton coated with metal or aluminum oxide nanoparticles in situ; the wettability of the aluminum melt on the surfaces of the silicon carbide particles is improved due to the existence of the metal or aluminum oxide nanoparticles, and the AlSiC composite material prepared after vacuum pressure aluminizing is higher in density, better in heat conductivity and good in structural controllability. By adjusting parameters such as the proportioning proportion, the forming process and the sintering process system, the silicon carbide crystal form and the porosity, pore size and distribution of the porous prefabricated blank are accurately controlled, and the quality requirement of the aluminum silicon carbide material on the silicon carbide porous prefabricated blank is met.

The application provides a method for preparing porous ceramics by sol modification of SiC particles and photocuring, which comprises the following steps: forming a uniform SiO2 coating on the surface of SiC particles by sol treatment; then, configuring the modified SiC particles into a photocuring printing slurry for manufacturing a SiC blank with a complex shape; and finally, preparing porous SiC ceramics through a debinding and sintering process. The SiO2 coating can not only improve the photocuring printing performance of the SiC particles, but also effectively avoid the direct reaction between Al and SiC to generate harmful phase Al4C3 in the subsequent metal infiltration process. The method is simple in process, controllable and stable and reliable in parameters, and the obtained porous SiC ceramics have a continuous three-dimensional pore structure, and the pore structure and size are suitable for the flow and complete filling of aluminum melt, so that the porous SiC ceramics can be used for preparing high specific SiC / Al composite materials with a complex structure, and the photocuring printing technology can be expected to be applied to the fields of deep color ceramic printing and the manufacturing of SiC / metal composite materials with a complex structure.

The invention provides a brazing connection method for porous SiC ceramic and 2507 duplex stainless steel, and belongs to the technical field of porous ceramic and metal welding, and the brazing connection method comprises the following steps: plating a layer of TiSn alloy brazing filler metal on the surface of the porous SiC ceramic as a plating layer by adopting ultrasonic-assisted brazing, and then carrying out polishing and ultrasonic cleaning to obtain a SiC / TiSn composite material; the surface of the 2507 duplex stainless steel is ground and then subjected to ultrasonic cleaning, and pretreated 2507 duplex stainless steel is obtained; and the pretreated 2507 duplex stainless steel, the high-entropy alloy brazing filler metal and the SiC / TiSn composite material are stacked from top to bottom and then subjected to vacuum brazing, and after the reaction is finished, natural cooling is conducted at the room temperature. According to the method, the TiSn alloy brazing filler metal is ultrasonically plated on the surface of the porous SiC ceramic with poor welding performance, the wettability of the TiSn alloy to the ceramic surface is high, the high-entropy alloy brazing filler metal is good in fluidity and can be well combined with a TiSn alloy plating layer, and the residual stress of the porous SiC ceramic and a metal reaction layer is reduced.

The application relates to the technical field of brush plating liquid preparation, in particular to a brush plating liquid for processing a gold-finger gold plating layer of a PCB and a preparation process thereof. The brush plating liquid comprises a nickel plating liquid and a gold plating liquid. The nickel plating liquid comprises nickel sulfate, acetic acid, deionized water and modified porous SiC-nano nickel particles. The gold plating liquid comprises potassium cyanide, potassium citrate, deionized water and wrapped porous SiC-nano silver particles. Through the process of nickel plating first and then gold plating, an effective physical barrier layer between copper and gold is formed by the nickel layer, which fundamentally prevents the mutual diffusion of copper and gold during high-temperature or long-term power use, and solves the problem of gold brittleness. The porous SiC preferentially bears the friction load, greatly reduces the wear rate of the plating layer, the modified porous SiC-nano nickel particles fill the micropores of the nickel layer, the wrapped porous SiC-nano silver particles fill the micropores of the gold plating layer, the double-layer plating layer structure is more compact, the corrosion resistance of the plating layer is improved, and the wrapped porous SiC-nano silver particles also effectively reduce the temperature rise and improve the current resistance of the gold finger.

The invention provides a preparation method of a low residual silicon SiC composite material and a preparation method of liquid phenolic resin, and relates to the technical field of preparation of SiC composites.The preparation method comprises the steps that a SiC fiber preform is prepared from SiC fiber bundles and placed in a graphite mold to be shaped, and a fiber preform with the graphite mold is obtained; preparing a SiC interface layer to obtain a porous SiC / BN / Si-C-N composite material with a graphite mold; depositing a SiC matrix to obtain a porous SiC / BN / Si-C-N / SiC composite material; and carrying out impregnation, cracking and siliconizing treatment on the porous SiC / BN / Si-C-N / SiC composite material by using liquid phenolic resin to obtain the SiC / BN / Si-C-N / SiC composite material. The SiC composite material prepared by the preparation method has the characteristics of small porosity, high strength and low preparation cost.

The invention relates to SiC ceramic based on improved precursor impregnation and pyrolysis and current reinforced sintering densification printing biscuit and a preparation method thereof. The particles of the SiC ceramic are of a core-shell structure with SiC as a core and a SiC-AlN solid solution as a shell. The preparation method comprises the following steps: (1) carrying out binder jet printing on composite powder containing SiC and AlN to respectively obtain a porous SiC biscuit and a sacrificial mold biscuit which is in a negative geometrical shape with the porous SiC biscuit; (2) the porous SiC biscuit and the sacrificial mold biscuit are subjected to debonding, dipping, curing and cracking, and a porous SiC reinforced biscuit and a sacrificial mold reinforced biscuit are obtained; and (3) assembling the porous SiC reinforced biscuit and the sacrificial mold reinforced biscuit according to a geometrical shape corresponding relation to form an assembly part, performing current reinforced sintering under uniaxial pressure, and then removing the sintered sacrificial mold to obtain the SiC ceramic material.

The invention relates to a ceramic connecting layer with a sandwich structure and a ceramic connecting piece, and belongs to the technical field of ceramic materials. The invention discloses a ceramic connecting layer with a sandwich structure, which comprises SiC-Si layers and Si layers, one Si layer is sandwiched between every two SiC-Si layers, and part of silicon in the Si layers enters the porous SiC-C structures of the SiC-Si layers. The invention also discloses a preparation method of the ceramic connecting layer with the sandwich structure, which comprises the following steps: sequentially stacking SiC-C slurry and / or SiC-C cast film with a silicon source, and then carrying out vacuum sintering to obtain the ceramic connecting layer with the sandwich structure. The ceramic connecting layer of the sandwich structure is adopted, thermal expansion coefficients of materials of all the layers are gradually transited, thermal expansion differences at the interface of silicon carbide ceramic and the connecting layer are reduced, thermal stress generated in the high-temperature treatment process and the high-low temperature application environment is effectively reduced, and the connecting stability is improved; and the method can be used for connecting small-size and large-size ceramic substrates.

The invention discloses a preparation method and application of a porous SiC / C composite microsphere wave-absorbing material, and relates to the technical field of electromagnetic wave absorbing materials. The invention aims to solve the technical problems that in the prior art, a high-activity SiC nanophase is difficult to uniformly and controllably introduce into a carbon matrix, and a SiC / C composite wave-absorbing material with a porous structure and a good impedance matching characteristic is difficult to construct in one step. The preparation method comprises the following steps: by taking an IRA-900 macroporous resin ball as an organic precursor with structure guiding and carbon source functions, dipping a SiO2 precursor solution and curing the SiO2 precursor solution in an internal pore channel and the surface of the resin ball in situ, so as to form a precursor in which SiO2 and organic resin are uniformly compounded on a microscopic scale; the preparation method comprises the following steps: firstly, preparing a SiO2 component, then carrying out carbonization and magnesiothermic reduction reaction, converting the SiO2 component into superfine SiC nano particles in situ under a relatively mild condition, and tightly combining the superfine SiC nano particles with a three-dimensional interconnected porous carbon skeleton formed by resin carbonization, so as to construct the porous SiC / C composite microspheres in one step.

The invention discloses a high-temperature-resistant silicon carbide crucible and a preparation method thereof, and relates to the technical field of silicon carbide crucibles, and the preparation method comprises the following steps: uniformly mixing alpha-SiC powder, composite resin and hexamethylenetetramine, adding ethanol, uniformly stirring, carrying out cold isostatic compaction, carrying out staged curing, and carrying out staged pyrolysis to obtain a porous SiC preform; soaking in a Ni2SO4 aqueous solution, and obtaining a nanowire layer SiC prefabricated body by adopting a chemical vapor reaction method; embedding the nanowire layer SiC prefabricated body into embedding powder, and preserving heat in an Ar atmosphere to prepare a transition layer to obtain a transition layer SiC prefabricated body; the preparation method comprises the following steps: uniformly mixing Yb2O3 powder, composite resin and polyvinyl butyral, adding ethanol, uniformly stirring, and carrying out film casting to obtain a Yb2O3 film; the Yb2O3 film is attached to the surface of the transition layer SiC prefabricated body, curing, pyrolysis, molten Si permeation in the Ar atmosphere and sintering are conducted, and the high-temperature-resistant silicon carbide crucible is obtained.

The invention provides a SiC catalytic composite material. The SiC catalytic composite material comprises a porous SiC matrix, a 3C-SiC nanowire doped with Ni is loaded on the hole wall of the porous SiC substrate; cuO / ZnO / CeO2 / NiO catalysts are loaded on the surfaces of the pore walls of the porous SiC substrate and the surfaces of the 3C-SiC nanowires. The invention also provides a preparation method of the SiC catalytic composite material and application of the SiC catalytic composite material in the field of catalytic reforming hydrogen production.

The invention belongs to the technical field of metal-based composite material preparation, and particularly relates to a high-strength aluminum-based composite material preparation method based on rapid laminar infiltration, which is characterized by comprising the steps of prefabricated body preparation, aluminum melt preparation, heating preparation, rapid laminar infiltration treatment and heat treatment, the aluminum melt comprises the following components: 0.1-6.0% of Ni, 0.2-2.0% of Fe, 0.1-0.5% of La and the balance of Al and inevitable impurity elements, and the aluminum melt comprises the following components in percentage by weight: 0.1-2.0% of Ni, 0.2-2.0% of Fe, 0.1-0.5% of La and the balance of Al and inevitable impurity elements. The total content of impurity elements is less than or equal to 0.05%; rapid laminar infiltration treatment: putting a mold into an extruder in place, putting the porous SiC prefabricated body on the mold, rapidly pouring the aluminum melt into the mold, closing the mold, and pressurizing; and carrying out T6 heat treatment to obtain the high-strength aluminum-based composite material. The method has the beneficial effects that the base material is the Al-Ni-Fe alloy, the alloy has a low eutectic point, the alloy fluidity is excellent at the eutectic point or hypoeutectic position, and efficient application of the high-strength aluminum-based composite material of the SiC with the high volume fraction (larger than or equal to 50%) is achieved under the technical conditions of extrusion casting and rapid laminar infiltration.