49results about "Silicon carbide" patented technology

A silicon-carbon negative electrode material includes a carbon skeleton having a pore structure and a silicon-based material arranged in the pore structure, where in a region formed by extending from a surface of the silicon-carbon negative electrode material inward by 10 nm away from the surface, a content of high-valence silicon is less than 25% relative to a total amount of low-valence silicon and the high-valence silicon, where the low-valence silicon is silicon with a valence of 0 to 2, and the high-valence silicon is silicon with a valence of 3 to 4.

The application relates to a preparation method of gaseous elemental carbon for synthesizing silicon carbide, which comprises the following steps: S1, placing a carbon source in a reaction chamber 1, heating the carbon source, and obtaining gaseous elemental carbon, wherein the carbon source is high-purity fullerene; S2, placing a silicon source in a reaction chamber 2, heating the silicon source, and heating to 1100-1900 DEG C; S3, under the protection of an inert gas atmosphere, the gaseous elemental carbon flows into the reaction chamber 2, heat preservation reaction is carried out for 4-10 h, the gaseous elemental carbon reacts with the silicon source, and after the reaction is completed, cooling is carried out, and silicon carbide is obtained. The silicon carbide prepared by the method has the characteristics of large particles and high purity, is beneficial to improving the performance of semiconductor materials, and has an excellent industrial application prospect.

Ultrafast Joule heating synthesis methods and systems, and more particularly, ultrafast flash Joule heating upcycling of fiber reinforced plastics (such as waste fiber reinforced plastics, glass fiber reinforced plastics, carbon fiber reinforced plastics, and / or quartz fiber reinforced plastics) and materials including fiber reinforced plastics (such as reinforced metal laminates including glass reinforced aluminum laminates and other glass reinforced metal laminates) to phase-controllable silicon carbide (SiC). Further, ultrafast Joule heating synthesis methods and systems for synthesis include SiC fibers / fibrils (such as SiC nanowires), SiC nanowires, and SiC-containing polymer composites, as well as B4C nanowires.

Regarding a SiC formed body, a small crystal grain size is considered to be preferable, because general wear occurs first at the crystal grain boundaries and therefore the small grain size leads to a reduction in particles generated during the wear. Meanwhile, a large crystal grain size leads to a reduction in volume resistivity, making a SiC formed body suitable for use as a heater among components for semiconductor manufacturing apparatuses. For these reasons, provided are a polycrystalline SiC formed body which has a low volume resistivity and a crystal grain size controlled within a specific range, and a method for producing the same. The polycrystalline SiC formed body has an average crystal grain size of 5.5 µm to 25.0 µm, a nitrogen concentration of 0.27×1020 atoms / cm3 to 5.4×1020 atoms / cm3, and a product of carrier density × Hall mobility of 4.0×1020 atoms / cmVsec to 100×1020 atoms / cmVsec.

This invention provides a rapid and energy-efficient pretreatment method for recovering rare earth elements (REEs) from ore, fly ash, and bauxite residue (red clay). [Solution] The present invention relates to an ultrafast flash Joule heating synthesis method, and more specifically, embodiments of the present invention include an ultrafast synthesis method for recovering metals from ore, fly ash, and bauxite residue (red clay).

The application belongs to the technical field of wave-absorbing materials, and particularly relates to a simple method for in-situ synthesis of FeSi@SiC high-temperature-resistant wave-absorbing material. The method comprises the following steps: dissolving Fe(NO3)3.9H2O in anhydrous ethanol, adding SiC powder, stirring, evaporating anhydrous ethanol in the solution, and heating to remove the combined water in the solid; grinding the solid after the combined water is removed into a powder sample, adding Fe powder and KCl, mixing uniformly, and performing reduction treatment; grinding the reduced solid powder thoroughly, adding hydrochloric acid solution, filtering, washing, and drying to obtain FeSi@SiC. The FeSi@SiC material is in-situ synthesized by the impregnation reduction method in one step, the preparation method is simple, the obtained FeSi@SiC material has high-temperature resistance and wave-absorbing performance, the physical properties do not change under the condition of 1300 DEG C, the material still has magnetism at 673K and excellent wave-absorbing performance, and has considerable industrial application value.

The application discloses a silicon carbide powder purification device and a silicon carbide powder purification method. The silicon carbide powder purification device comprises a crucible, a first gas-permeable partition, a second gas-permeable partition, a first catalyst, a second catalyst and a third catalyst. The bottom of the crucible is provided with a first air inlet, a second air inlet and a third air inlet. The first gas-permeable partition is internally formed with a first space for accommodating first silicon carbide powder. The second gas-permeable partition is located outside the first gas-permeable partition. The first catalyst is used for being laid on the upper surface of the first silicon carbide powder, and the second catalyst is used for being laid on the upper surface of the second silicon carbide powder. The third catalyst is laid on the bottom of the gas-permeable space. The silicon carbide powder purification device can solve the problem of impurity removal of silicon carbide powder with different particle sizes, and can also solve the key problems of efficient discharge of impurities and reduction of calcination loss, thereby providing high-quality, high-quantity and high-consistency powder guarantee for large-size silicon carbide single crystal.

A negative electrode active material for a lithium secondary battery, according to the present invention, includes a silicon-carbon composite including silicon nanoparticles and a carbon-based matrix, wherein the silicon-carbon composite includes 0.5-7 parts by weight of polyvinyl butyral (PVB) based on 100 parts by weight of the silicon nanoparticles.

A negative electrode active material for a lithium secondary battery according to the present invention includes a silicon-carbon-based composite including: silicon nanoparticles; a carbon-based matrix; and a conductive additive, wherein the content of the conductive additive may be 0.2-10 wt% relative to the silicon nanoparticles in the composite.

The present invention relates to nanoparticulate stoichiometric doped or non-doped silicon carbide SiC in the form of secondary particles, which consist of agglomerates of SiC primary particles, wherein the primary particles have a particle size in the range of 40-100 nm and the secondary particles have an average size of 1-10 μm. Furthermore, the present invention relates to an anode of a secondary lithium-ion battery containing the SiC according to the invention and a secondary lithium-ion battery having this anode.

A method of manufacturing silicon carbide seed crystal and method of manufacturing silicon carbide ingot are provided. The silicon carbide seed crystal has a silicon surface and a carbon surface opposite to the silicon surface. A difference D between a basal plane dislocation density BPD1 of the silicon surface BPD1 and a basal plane dislocation density BPD2 of the carbon surface satisfies the following formula (1):D=(BPD1−BPD2) / BPD1≤25%  (1).

A method for forming polycarbosilanes used as precursors for producing silicon carbide fibers or composites includes providing poly(dimethylsilane) (PDMS) as a solid, providing a catalyst, which includes phenylboronic acid or boric acid, and reacting the solid PDMS with the catalyst at a temperature of about 340oC for a sufficient period of time to form the polycarbosilanes. Alternatively, the method may include providing a liquid silane formed from PDMS and heating the liquid silane and the catalyst at a temperature ranging from about 100oC to about 200oC for about 1 to about 2 hours. After heating, reacting the liquid silane with the catalyst at a temperature ranging from about 220oC to about 340 oC for a sufficient period of time to form the polycarbosilanes. The ceramic yield for the synthesized polycarbosilanes is in the range between about 60% to about 74% under inert gas upon heating to 1000oC.

A silicon carbide powder according to the present invention is an aggregate of silicon carbide particles containing the element nitrogen. If the powder is measured in a region down to the depth of 12 nm from an outermost surface by X-ray photoelectron spectroscopy, an integral value of a ratio of a detection intensity of the element nitrogen to a total detection intensity of the element carbon and the element silicon is 0.05 or greater. Moreover, the slope of a change in the ratio thereof is -0.0008 or less. A specific surface area measured using nitrogen is preferably 5 m2 / g to 40 m2 / g. Furthermore, the 50% particle diameter D50 in a quantity distribution measured by observation with a scanning electron microscope is preferably 50 nm to 1000 nm. The present invention also provides a method for manufacturing the silicon carbide powder.

The present application relates to an ultra-fast flash evaporation joule heating synthesis method and a system for implementing the same. The ultra-fast flash evaporation joule heating synthesis method and system, and more particularly, an ultra-fast synthesis method for recovering metals from ores, fly ash, and bauxite residue (red mud).

The present invention relates to a graphite and silicon composite and a lithium secondary battery including same. The graphite and silicon composite includes graphite with a high surface area. By using the graphite with a high surface area, an adhesion effect with silicon particles can be increased and pressure can be absorbed inside a negative electrode material when silicon expands. In addition, employment of the graphite and silicon composite as a negative electrode active material enables the provision of a lithium secondary battery that exhibits excellent initial efficiency, suppression of volume expansion, and excellent lifespan characteristics.

The application discloses a method for deep boron removal of silicon carbide powder and silicon carbide raw material, which comprises the following steps: placing the silicon carbide raw material in a plasma reaction device, inputting a working gas and applying a plasma power source, and performing low-temperature plasma pretreatment to obtain pretreated silicon carbide raw material; wherein the working gas comprises at least one of inert gas and oxygen; mixing the pretreated silicon carbide raw material with deionized water to obtain a suspension, adjusting the pH to 4-8, adding a functionalized adsorption material for adsorption treatment, and performing solid-liquid separation to obtain silicon carbide powder; wherein the functionalized adsorption material comprises an adsorption material containing hydroxyl and / or amine groups. The application combines low-temperature plasma pretreatment with deep boron removal of the functionalized adsorption material, and synergistically achieves the effect of efficient, low-consumption and environmentally-friendly boron removal. The method has the characteristics of low energy consumption, small pollution and easy mass production, and is suitable for the preparation of low-boron silicon carbide powder for semi-insulating silicon carbide crystal growth.

A silicon carbon composite, a negative electrode active material, a negative electrode composition, a negative electrode, a lithium secondary battery, a battery module, and a battery pack are provided. The silicon carbon composite satisfies a condition of 1.3≤((B+C) / A)<4, wherein A is an intensity of a peak having a chemical shift value in the range of 20 ppm to −15 ppm in a 29Si-MAS-NMR spectrum, B is an intensity of a peak having a chemical shift value in the range of −20 ppm to −100 ppm in the 29Si-MAS-NMR spectrum; and C is an intensity of a peak having a chemical shift value in the range of −110 ppm to −140 ppm in the 29Si-MAS-NMR spectrum.

The present invention 29 This invention relates to a silicon-carbon composite having a chemical shift value in the range of 20 ppm to -15 ppm in the Si-MAS-NMR spectrum, a peak B in the range of -20 ppm to -100 ppm, and a peak C in the range of -110 ppm to -140 ppm, as well as a negative electrode active material, negative electrode composition, negative electrode, lithium secondary battery, battery module, and battery pack containing the same.

The application discloses a kind of aluminum ash efficient utilization method, after being finely ground, preheating, microwave heating oxidation denitrification is added to fluidized bed under the assistance of large particle wave-absorbing material, aluminum, aluminum nitride in aluminum ash is converted into alumina, nitrogen, after heat exchange, fluoride, chlorides and other salts are removed by microwave vacuum distillation to denitrification residue, after screening, wave-absorbing material is recycled to microwave flow chlorination deoxidation, alumina, silicon oxide and magnesium oxide in aluminum ash are converted into aluminum chloride, silicon chloride and magnesium chloride, and magnesium chloride enters tailings, and aluminum chloride and silicon chloride are recovered by multistage condensation, respectively, unreacted chlorine and carbon monoxide are recycled by multistage separation.The application uses microwave heating, without balling, oxidation denitrification, distillation desalination and chlorination deoxidation reaction rate is fast, efficiency is high, raw material is widely used, system energy utilization rate is high, can realize large-scale clean and efficient utilization of aluminum ash, with good economic benefit and social benefit.

The present application relates to the technical field of composite materials, and specifically provides a preparation device and method of diamond / silicon carbide composite material and the composite material; the preparation device comprises a furnace body, a heating body, a sintering area, a gas flow meter, a gas inlet, an initial gas pressure control unit, a gas source valve, a gas filling valve, a constant gas pressure control unit, a gas outlet, an evacuation valve, a vacuum pump system, a gas release valve and a constant gas pressure auxiliary unit; the preparation method comprises preparing a diamond preform; and placing the diamond preform and silicon into the preparation device to perform a sintering reaction; by the preparation device, the severe diffusion and reaction of silicon in the infiltration process are controlled by introducing inert protective gas, and the gas flow rate and gas pressure and other parameters in the furnace body are stably regulated and controlled; and the method does not need to add resins, graphite and other carbon sources in the preparation process of the diamond preform, thereby simplifying the process; the prepared composite material reduces the production and preparation cost, and has better thermal and mechanical properties.

The present invention stands directed at polymer derived ceramic material, More specifically, boric acid and 2,4,6-trimethyl-2,4-6-trivinylsilazane are reacted to form a polymeric resin followed by the addition of a crosslinking agent and then subsequent crosslinking and pyrolysis to provide an improved ceramic yield.

The application discloses a method for deeply removing boron from silicon carbide powder and silicon carbide raw material, which comprises the following steps: mixing the silicon carbide raw material, a complexing agent and deionized water, adjusting the pH to 3-5, and performing wet complexation extraction pretreatment to obtain a suspension; mixing the suspension with an adsorbent and then performing adsorption treatment, and performing solid-liquid separation to obtain the silicon carbide powder, wherein the content of boron in the silicon carbide powder is less than or equal to 0.005 ppm; wherein the adsorbent comprises at least one of a boron removal resin and a porous material loaded with a hydroxylated metal oxide. The application combines the wet complexation extraction pretreatment and the adsorption treatment, realizes efficient synergy of mild desorption of boron and targeted capture of boron, reduces the cost and pollution, reduces the boron content of the silicon carbide raw material from 0.1 ppm-1 ppm to below 0.005 ppm, and meets the growth requirement of semi-insulating silicon carbide crystals.

The present disclosure relates to the technical field of battery negative electrode materials, and disclosed are a carbon material, a silicon-carbon negative electrode material, and a preparation method for and a use of the silicon-carbon negative electrode material. In the negative electrode material, silicon is distributed within pores of a porous substrate, and the volume expansion of silicon in a lithium deintercalation process is suppressed by using the pore structure of the porous substrate, thereby improving the cycle performance of the negative electrode material. The silicon-carbon composite material exhibits high sphericity, avoids poor compression resistance due to numerous edges and corners during rolling, and can mitigate the problems of continuous formation of solid electrolyte interface (SEI) films, reduced capacity and poor cycle performance caused by low strength. Porous carbon is prepared using a nanoscale carbon nanotube, facilitating improvement of the electrical conductivity of the porous carbon; and in addition, a tin or germanium element doped into the negative electrode material facilitates deintercalation of lithium ions by lowering the energy barrier of lithium ion transition, thereby improving the initial coulombic efficiency.

The present application relates to solid waste treatment technical field, disclose a kind of process for preparing silicon carbide based on super-enthalpy calcination energy supply of coal gangue and waste, comprising: coal gangue is crushed and sieved, while using the first part of recovery heat of calcining furnace backflow to preheat and send into furnace calcination;Calcination product is leached by hydrochloric acid, liquid phase extraction by-product aluminum salt, solid phase interception obtains silicon dioxide residue;Then, silicon dioxide residue is uniformly mixed with high-carbon waste;System dispatching second part of recovery heat provides high-temperature environment for downstream, drive mixture material to occur carbothermic reduction reaction, product is finally obtained after removing impurities by acid liquid step washing silicon carbide.The present application integrates heat cascade reuse and mineral phase chemical elution, reduces the cost of silicon-carbon source procurement and external heat consumption, and completes the high-value conversion of coal gangue and high-carbon waste.

The application discloses a preparation method of a novel dual-rare earth modified SiC electromagnetic wave absorbing material with a multi-frequency spectrum response and a product prepared by the method. A full-silicon molecular sieve MFI prepared by a hydrothermal reduction method is used as a precursor, high-activity Si / SiO2 powder is obtained through a magnesium hot reduction method, and then the high-activity Si / SiO2 powder is mixed with dual-rare earth elements at a proper ratio, and a composite material rich in SiC nanowires, SiC, Ce5Si4 and Pr5Si4 nanoparticles is successfully prepared through freeze drying and carbonization processes. Multiple heterojunction interfaces constructed in the material are efficiently excited under the action of an applied electromagnetic field, and the multiple heterojunction interfaces induce strong polarization relaxation in a low-frequency (2-6 GHz) wave band, a medium-frequency (6-12 GHz) wave band and a high-frequency (12-18 GHz) wave band, so that the polarization loss capacity of the material is significantly enhanced, and important technical ideas and approaches are provided for the design of the electromagnetic wave absorbing material with the multi-frequency spectrum response.

The application provides a preparation method of high-strength silicon carbide aerogel with a mesoporous structure, and comprises the following steps: mixing an aldehyde precursor, a phenolic precursor, a solvent, a gas-phase reaction catalyst and a cross-linking reaction catalyst, and uniformly stirring to obtain a sol; performing a solvothermal reaction on the sol, and obtaining a gel after cooling; removing the solvent in the gel through supercritical drying to obtain an organic aerogel; heating and raising the temperature of the organic aerogel to perform carbonization and cracking, and obtaining a carbon aerogel after cooling; heating and raising the temperature of the carbon aerogel to perform high-temperature gas-phase silicon infiltration, and obtaining a silicon carbide aerogel after cooling. The phenolic aldehyde-based carbon aerogel with adjustable pore structure and stable physical and chemical properties is used as a template, the silicon carbide aerogel with good thermal stability and excellent high-temperature heat insulation performance is prepared through a high-temperature gas-phase silicon infiltration process, the problems of traditional porous carbon templates and biomass templates, such as difficult pore structure regulation and control and too many impurities, are overcome, and the application of the silicon carbide aerogel in special equipment is promoted.

The application discloses a method for deeply removing impurities from silicon carbide micro powder for photovoltaic, which comprises the following steps: after the raw material of the silicon carbide micro powder is chlorinated and roasted to remove impurities, the obtained roasting product is subjected to a hydrothermal leaching reaction in an alkaline solution; the obtained product is subjected to solid-liquid separation, water washing and drying, and then 2N or above grade silicon carbide micro powder is obtained; and a microwave field is applied synchronously during the hydrothermal leaching reaction. In the method, the deep impurity elements of the micro powder are converted into low-boiling-point chlorides by high-temperature gas-phase chlorination and are removed by volatilization, and the leaching reaction of the roasting product and the alkaline solution is synergistically strengthened by the microwave field, so that the free silicon and the silicon dioxide impurities are completely dissolved and stripped. The method has the advantages of simple process flow, high impurity removal efficiency, no fluorine and environmental protection, and is easy to popularize and apply in the production of high-purity raw materials for photovoltaic, and the purity of the silicon carbide micro powder can be improved to 99.95% or above.

This disclosure provides a method and system for preparing low-defect silicon carbide based on fly ash composition control. By using industrial solid waste fly ash as the main silicon and carbon source, combined with precise composition control and microwave gradient reduction process, and innovatively introducing in-situ monitoring and artificial intelligence closed-loop control, it not only achieves low-cost and resource-efficient utilization of raw materials and significantly reduces energy consumption and preparation costs, but also precisely suppresses the generation of crystal defects by dynamically adjusting reaction parameters in real time. Ultimately, it successfully obtains high-performance silicon carbide materials with complete crystal form, uniform morphology, and low defect density, while realizing the intelligent and precise controllability of the preparation process.

A method for forming polycarbosilanes used as precursors for producing silicon carbide fibers or composites includes providing poly(dimethylsilane) (PDMS) as a solid, providing a catalyst, which includes phenylboronic acid or boric acid, and reacting the solid PDMS with the catalyst at a temperature of about 340° C. for a sufficient period of time to form the polycarbosilanes. Alternatively, the method may include providing a liquid silane formed from PDMS and heating the liquid silane and the catalyst at a temperature ranging from about 100° C. to about 200° C. for about 1 to about 2 hours. After heating, reacting the liquid silane with the catalyst at a temperature ranging from about 220° C. to about 340° C. for a sufficient period of time to form the polycarbosilanes. The ceramic yield for the synthesized polycarbosilanes is in the range between about 60% to about 74% under inert gas upon heating to 1000° C.

The application provides a method and system for preparing high-purity SiC through self-adaptive collaborative conversion of fluctuating fly ash silicon-aluminum ratio, comprising: adopting a differential acid etching technology for silicon-aluminum separation; performing differential acid treatment on high-silicon and low-silicon fly ash to efficiently separate silicon-aluminum components in the fly ash in an acid activation-ultrasonic mechanical chemical coupling mode; adopting a deep deterministic policy gradient algorithm to construct a temperature decision model for precise temperature control; establishing a temperature decision model, and optimizing a temperature rising path and a holding time based on the deep deterministic policy gradient algorithm; in-situ resource utilization of excessive Al2O3 in a low-silicon phase to prepare high-performance SiC; and converting the excessive Al2O3 in the low-silicon phase into a functional carrier that can be used for preparing a composite material through an in-situ chemical reaction. The acid activation-mechanical chemical coupling method is used to dissociate silicon-aluminum in fly ash, a dynamic optimization carbon thermal reduction path mode is fused with a reinforcement learning algorithm, and the two modes are coupled to improve the quality and efficiency of SiC material prepared from fly ash.