398 results about "Pyrolytic carbon" patented technology

The invention discloses a method for recovering phosphorus through anaerobic digestion by adding sludge-based biochar, which comprises the following steps of: firing dewatered sludge serving as a raw material under an anaerobic condition to obtain carbonized carbon; or firing under an aerobic condition to obtain pyrolytic carbon, adding any sludge-based biochar obtained by firing into the hydrothermal dewatered sludge, and carrying out anaerobic digestion on the hydrothermal dewatered sludge; the hydrothermal dewatered sludge is obtained by performing hydrothermal pretreatment on dewatered sludge; and carrying out phosphorus recovery on the sludge-based biochar subjected to anaerobic digestion by utilizing a magnetic separation method. Compared with the traditional method for recovering the phosphate fertilizer from the sludge incineration ash, the recovery method disclosed by the invention is green and pollution-free, belongs to a sludge treatment mode of treating waste with waste, realizes effective combination of a heat treatment mode and a biological treatment mode, and has a good practical application value. Moreover, the prepared sludge-based biochar has the property of magnetism, so that the recovery rate of the subsequent blue iron ore is increased, and the separation difficulty and economic investment are reduced.

A composite, comprising a binder, the binder comprising one or more of polymeric, metallic, or ceramic, or pyrolytic carbon binder and a nanostructured carbon having a cellular structure. The cellular structure comprises one or more cell walls having a structure formed by a template and one or more cavities. Each cavity is substantially enclosed by the one or more cell walls and substantially unimpregnated by a liquid or solid.

The invention belongs to the technical field of lithium ion battery negative electrode materials, and particularly relates to a method for preparing porous carbon through secondary utilization of porous carbon airflow fine powder, which comprises the following steps: (S1) mixing the porous carbon airflow fine powder and a binder according to a mass ratio of 100: (15-30), and then carrying out curing reaction to obtain a precursor; the binder comprises thermosetting phenolic resin, an epoxy silane coupling agent and fumed silica; (S2) after crushing and screening the precursor, performing pyrolysis carbonization in an inert atmosphere to obtain pyrolytic carbon; and (S3) activating the pyrolytic carbon under an activation atmosphere condition to obtain the porous carbon material. According to the method, the specific adhesive is utilized, the airflow fine powder which is difficult to recycle is well reutilized, additional equipment does not need to be added, the airflow fine powder does not need to be subjected to complicated particle size screening, and secondary utilization of the airflow fine powder can be completed through existing equipment.

The invention relates to the technical field of negative electrode materials, in particular to a cylindrical silicon-carbon negative electrode material and a preparation method and application thereof. The silicon-carbon negative electrode material comprises a cylindrical porous carbon skeleton with the diameter of 5-15 [mu] m and the length of 2-20 [mu] m, 10-65% of amorphous nanometer silicon is deposited on the inner wall of a pore channel, a pyrolytic carbon layer is coated on the inner wall of the pore channel, and the carbon skeleton can be doped with 0-10% of nitrogen. The preparation method comprises the steps of resin extrusion molding, carbonization, pore forming, airflow crushing, nanometer silicon deposition and pyrolytic carbon coating. The obtained material has excellent compression resistance and conductivity, is simple to prepare, and can improve the capacity, the first effect and the conductivity and reduce the expansion rate when being used for a lithium battery.

The invention provides a preparation method of a high-temperature-resistant graphite pipe for spectral analysis, and belongs to the technical field of spectral analysis, and the preparation method comprises the following steps: S1, preparing a high-purity graphite pipe matrix and carrying out surface activation treatment; s2, preparing composite sol, wherein the composite sol is formed by mixing silica sol, molybdate and phytic acid; s3, infiltrating the composite sol into the graphite matrix by adopting a vacuum-pressurization alternate impregnation process; s4, carrying out stepped heating heat treatment in an inert environment to form a SiC-MoSi composite reinforced phase; and S5, depositing a pyrolytic carbon layer on the inner wall of the graphite pipe. The silica sol, the molybdate and the phytic acid have a synergistic effect to form a SiC-MoSi composite phase, the phytic acid can prevent the molybdate from gathering and can promote the growth of SiC whiskers in heat treatment, so that the anti-oxidation temperature of the graphite pipe is increased, the temperature resistance and the heat stability of the graphite pipe are improved, and the anti-oxidation performance of the graphite pipe is improved. And finally, the use frequency of the graphite pipe is greatly increased.

The invention relates to a preparation method of a ceramic-based composite material, in particular to a preparation method of a ceramic-based composite material with a pyrolytic carbon-carbon nanotube interface, which is used for solving the problem that in the aspect of improving the thermal conductivity of an interface layer, metals such as Fe, Co, Ni and the like are widely used as catalysts for growing carbon nanotubes at present, so that the thermal conductivity of the interface layer is improved. Carbon nanotubes obtained through a traditional preparation method are prone to agglomeration and uneven in distribution, the risk of the preparation process is high, the carbon nanotubes are not suitable for large-scale production, although metal particles can be reduced through a chemical plating method, the particle sizes of the metal particles are not controlled, the distribution of the metal particles is uneven, and the requirement of a chemical vapor reduction method for distribution of an earlier-stage metal salt solution is high. And the defect is difficult to realize easily. According to the preparation method of the ceramic-based composite material with the pyrolytic carbon-carbon nanotube interface, the ceramic-based composite material with the pyrolytic carbon-carbon nanotube interface is finally obtained through pretreatment, solution A preparation, metal salt solution in-situ reduction and chemical vapor deposition in sequence.

The invention discloses a ceramic component gradient modified C / C-SiC-ZrC composite material and a preparation method thereof, and belongs to the technical field of carbon / carbon composite material matrix modification preparation, a carbon fiber preform and a heating element are placed in chemical liquid phase vaporization deposition equipment, a precursor solution is added until the carbon fiber preform is fully soaked, and a ceramic component gradient modified C / C-SiC-ZrC composite material is obtained; and carrying out chemical liquid phase vaporization deposition reaction to obtain the low-density C / C composite material with porosity in unidirectional gradient distribution. And putting the mixture into a graphite crucible with a carbon-rich area facing downwards and a carbon-less area facing upwards, completely putting the graphite crucible into the ceramic powder for modification, reacting and infiltrating, and cooling to room temperature to obtain the C / C-SiC-ZrC composite material with the gradient modified ceramic components. The end with high ceramic content endows the material with a high-temperature thermal protection function, the end with high pyrolytic carbon content can effectively conduct heat generated in a ceramic-rich area, and the end with low ceramic content can effectively conduct heat generated in a ceramic-rich area. Due to the gradient design from the ceramic-rich area to the carbon-rich area, the material has high-temperature oxidation resistance and ablation resistance and is light, and lightweight design of an aerospace thermal protection structure is facilitated.

The invention discloses an expansion-resistant lithium battery pole piece material for an unmanned aerial vehicle and a preparation method of the expansion-resistant lithium battery pole piece material, and belongs to the technical field of lithium batteries. Silicon dioxide / carbon fiber composite powder serves as a matrix, the surface of the matrix is coated with a long-chain alkyl cardanol grafted glucose layer, and pyrolysis carbonization is performed to obtain the expansion-resistant lithium battery pole piece material. Carboxyl groups in glucose and isocyanate on the surface of the modified silicon dioxide / carbon fiber composite powder are subjected to an amine esterification reaction, carbon dioxide is generated, the porosity of the material is further improved, cardanol-coated lithium-containing composite powder is obtained, nanometer aluminum oxide is deposited on the cardanol-coated lithium-containing composite powder through a coprecipitation method, and the composite material is obtained. By forming a ternary composite structure with the silicon dioxide / carbon fiber composite powder as a core layer, the carbonized long-chain alkyl cardanol grafted glucose as a middle layer and the nanometer aluminum oxide as an outermost layer, the volume expansion can be better and synergistically relieved on the premise that the porosity is not affected.

The invention provides a high-strength winding thin-wall SiC composite cladding tube and a preparation method thereof. A preparation method of a high-strength winding thin-wall SiC composite cladding tube comprises the steps that silicon carbide fibers are wound and laid around a core mold, the winding pre-tightening force is smaller than or equal to 10 N. The winding mode comprises the first mode that one layer of annular winding is conducted firstly, then one layer of spiral winding is conducted, and the number of fiber intersection points in the whole annular direction at a certain position of the outer surface of the core mold is 1. One-layer annular winding is carried out firstly, then two-layer spiral winding is carried out, the number of fiber intersection points in the whole annular direction at a certain position of the outer surface of the core mold is 3, and a prefabricated body is obtained; carrying out a densification deposition process on the preform, wherein the densification deposition process comprises PyC pyrolytic carbon interface deposition, CVI chemical vapor infiltration and CVD chemical vapor deposition; and precise inner circle and outer circle machining is conducted, and the SiC composite cladding pipe is obtained. According to the preparation method disclosed by the invention, through a specific dry winding mode and a densification deposition process, the SiC composite material tube blank is higher in density and better in mechanical property.

The invention provides a method for improving the reduction performance of pyrolytic carbon in biological sludge and application of the pyrolytic carbon in reduction of steel dust and sludge, and aims at solving the problems of high energy consumption and high carbon emission of a traditional reducing agent in the steel industry and promoting efficient utilization of biomass resources in the field of steel and iron metallurgy. The method comprises the following steps: extracting biological sludge carbon through a toluene solvent to remove oil, and deashing through a sulfuric acid solution, so that the adsorption capacity and catalytic performance of the biological sludge carbon are enhanced, and the reduction efficiency of the biological sludge carbon in the ferrous metallurgy process is improved. The biological sludge carbon subjected to dust removal and oil removal treatment has the specific surface area of 159 m < 2 > / g, the pore volume of 0.14 cm < 3 > / g and the average pore size of 3.4 nm, the specific surface area is remarkably increased, the metallization ratio after the reduction reaction is also greatly improved, and the effectiveness of the method in the aspect of improving the reduction performance of the biological sludge carbon is proved. The carbon emission of the iron and steel industry can be reduced, and powerful support is provided for sustainable development of the iron and steel industry.

The invention relates to the field of energy, in particular to a graded porous carbon material and a preparation method thereof.The method comprises the steps that thermoplastic phenolic resin is prepared, and the thermoplastic phenolic resin is low-molecular-weight resole; curing the thermoplastic phenolic resin to obtain thermosetting phenolic resin; carbonizing the thermosetting phenolic resin to obtain a carbide; and activating the carbide to obtain the graded porous carbon. According to the method, the micro-mesoporous graded carbon is formed, conveying holes matched with the deposition pore volume are provided, the pore channel resistance is reduced, and the silicon loading efficiency is improved; the graphitization degree is obviously improved, so that the conductivity of pyrolytic carbon is improved.

The invention relates to a high-performance hafnium-based ultrahigh-temperature ceramic-based composite material and a preparation method thereof. The method comprises the following steps: depositing pyrolytic carbon on the carbon fiber surface of a carbon fiber preform through a CVD (Chemical Vapor Deposition) method; preparing a hafnium oxide interface layer on the surface of the pyrolytic carbon through an atomic layer deposition method, and performing ultra-fast annealing treatment to form a pyrolytic carbon-hafnium oxide composite interface layer; carrying out a reaction with a matrix containing a pyrolytic carbon-hafnium oxide composite interface layer through an impregnation pyrolysis method; a hafnium carbide coating is prepared on the surface of the composite material matrix through a CVD method; and preparing a hafnium oxide coating on the surface of the hafnium carbide coating through an atomic layer deposition method, and carrying out ultra-fast annealing treatment to prepare the high-performance hafnium-based ultra-high-temperature ceramic-based composite material. According to the preparation method, the pyrolytic carbon-hafnium oxide composite interface layer is prepared by adopting an atomic layer deposition process and depending on ultra-fast annealing treatment, and meanwhile, the hafnium carbide-hafnium oxide composite coating is prepared, so that the mechanical property of the composite material in a high-temperature aerobic environment is remarkably improved.

The invention discloses a lignocellulose biomass-based hard carbon negative electrode material as well as a preparation method and application thereof. The method comprises the following steps: carrying out hydrothermal pretreatment on lignocellulose biomass by using low-corrosivity maleic acid, and regulating and controlling the composition of the lignocellulose biomass, the maleic acid and the lignocellulose to obtain a precursor rich in lignin and cellulose; in the pyrolysis and carbonization process, the thermal stability of the precursor is improved, and the lignin can more effectively inhibit the rapid concentrated pyrolysis of cellulose, so that the rearrangement of pyrolysis products is weakened. The method is beneficial for preventing overgrowth of hard carbon graphite microcrystals during high-temperature carbonization, so that the hard carbon material with large interlayer spacing and abundant small-size closed pores is prepared. The hard carbon material shows high specific capacity and excellent rate capability when being applied to the negative electrode of the sodium-ion battery. Meanwhile, xylose and furfural generated by decomposition of hemicellulose in a liquid phase can be effectively collected, and full-component utilization of biomass is achieved. The requirements of green production are met, and industrial application is easy to realize.

The invention relates to the technical field of coal gangue pyrolysis separation, and discloses a coal gangue pyrolysis carbon ash separation reactor which comprises a base and further comprises a processing mechanism which comprises a driving disc fixedly connected to the top end of the base, a driving assembly arranged above the base and a feeding cylinder arranged on the driving assembly, the conveying assembly and the separating mechanism are arranged above the base, the separating mechanism comprises a fixing plate fixedly connected to the top end of the base and a separating assembly arranged on the outer side of the fixing plate, and the processing barrel is driven by a driving disc to obliquely rotate, so that coal gangue repeatedly slides up and down in the barrel and collides with multiple layers of filter plates; according to the device, hot air flow is promoted to be in full contact with materials while particles are crushed, the problem of uneven local temperature of traditional static pyrolysis is avoided, meanwhile, a linear array structure is formed by the filter plates and the connecting rods, the material disturbance frequency is increased, 360-degree rotary heating is achieved in cooperation with hot air flow introduced through an air valve, the pyrolysis efficiency and uniformity are remarkably improved, and carbon residues are reduced.

The invention discloses a method for preparing a C / C-SiC composite material through multi-stage recovery of carbon / carbon composite material processing waste, and belongs to the technical field of C / C composite material preparation. The method comprises the following steps: carrying out multi-stage screening treatment on the carbon / carbon composite material processing waste, and screening and separating short carbon fibers and pyrolytic carbon powder; mixing the screened short carbon fibers and pyrolytic carbon powder with phenolic resin, industrial silicon powder and SiC powder, and preparing a fiber reinforced resin block in a mold pressing manner; and carrying out one-step continuous carbonization and ceramic heat treatment on the fiber reinforced resin block to finally obtain the C / C-SiC composite material. According to the method, high-added-value recycling of the C / C processing waste is achieved, the process is simple, the cost is low, operation is convenient and fast, the problems of resource waste and environmental pollution caused by existing waste treatment are solved, and the prepared C / C-SiC composite material is excellent in performance and can be widely applied to the fields of aerospace, high-end manufacturing and the like.

The invention relates to a preparation method of a high-thermal-conductivity Cf / SiC composite material, belongs to the technical field of fiber reinforced ceramic matrix composite material preparation, solves the technical problems of long preparation period and high cost, and comprises the following steps: chemical vapor infiltration: depositing a pyrolytic carbon interface on the fiber surface of a fiber preform; preparing a catalyst solution; immersing the fiber preform deposited with the pyrolytic carbon interface into a catalyst solution, and carrying out vacuum impregnation; carrying out heat treatment on the pretreated fiber preform; carrying out chemical vapor infiltration on the Cf / SiC composite material on which the SiC nanowires grow; carrying out impregnation pyrolysis on the precursor, and carrying out vacuum impregnation on an ultrahigh-temperature ceramic precursor and a phenolic resin solution; and infiltrating the reaction melt to obtain the high-thermal-conductivity Cf / SiC composite material. The method is used for preparing the high-thermal-conductivity Cf / SiC composite material.

The invention provides a fiber-bismuth ferrite-polymer converted ceramic wave-absorbing composite material and a preparation method and application thereof, and the fiber-bismuth ferrite-polymer converted ceramic wave-absorbing composite material comprises the following components by volume fraction: 10-40% of a fiber reinforcement, 1-10% of a fiber interface and 50-89% of a ceramic matrix, the ceramic matrix comprises a bismuth ferrite-based ceramic phase which accounts for 10-45% of the ceramic matrix and a polymer conversion ceramic phase which is distributed around the bismuth ferrite-based ceramic phase and accounts for 55-90% of the ceramic matrix, and the polymer conversion ceramic phase is selected from one or more of SiC, Si3N4, SiOC, SiCN and SiBCN; the fiber interface is selected from one or more of pyrolytic carbon, boron nitride and silicon carbide. The bismuth ferrite-based material is combined with the fiber-reinforced polymer conversion ceramic, so that the wave-absorbing effect can be further improved, and the high-temperature stability and oxidation resistance of the material can be remarkably improved.

The application discloses a preparation method of a carbon molecular sieve adsorbent for methane-nitrogen separation. The method comprises the following steps: 1) grinding graphite powder and placing the same in a metal salt solution, drying after sufficient stirring to obtain modified graphite; 2) placing phenolic resin powder in a metal salt solution, drying after sufficient stirring to obtain modified resin; 3) mixing the modified graphite and the modified resin, adding tar into the mixture, kneading and then extruding into a strip shape; 4) sufficiently drying the formed material, then transferring the material into a gas atmosphere calcination furnace, and calcining the material under an inert gas atmosphere for a certain time; and 5) performing programmed temperature heating on the obtained material under an inert gas atmosphere, introducing a carbon source, and depositing pyrolytic carbon on the surface of the material by a gas phase deposition method to obtain a carbon molecular sieve adsorption material. The carbon molecular sieve material is used as an adsorbent by adopting a pressure swing adsorption technology, has high adsorption capacity for nitrogen and high methane-nitrogen selectivity in methane-nitrogen separation application, and has a good industrial application prospect.

According to the catalyst for generating ethylene through electrocatalytic reduction of carbon dioxide, a CuO / SrCO3 heterojunction is synthesized through high-temperature liquid-phase pyrolysis and carbonization, an energy barrier of a reaction intermediate can be optimized through the electron effect of a heterojunction interface carried by the catalyst, efficient adsorption of OCHCHgroups of the reaction intermediate is achieved, and the catalytic activity of ethylene is improved. Further proton coupling of the intermediate is promoted, and finally, a target reduction product C2H4 is efficiently generated; meanwhile, the stability of the structure is guaranteed by a stable heterojunction surface of the heterojunction, so that the heterojunction has excellent durability.

The invention relates to the technical field of lithium ion battery negative electrode materials, in particular to a preparation method of a silicon-carbon composite negative electrode material with improved safety, which comprises the following steps: (S1) reacting a first phenol monomer, a second phenol monomer and an aldehyde monomer, sequentially curing twice to obtain a phenolic resin block, and sequentially crushing, pre-oxidizing, pyrolyzing and carbonizing to obtain a silicon-carbon composite negative electrode material; pyrolytic carbon is obtained; the second phenol monomer is cardiac phenol; (S2) carrying out activated pore-forming on the pyrolytic carbon, and carrying out high-temperature treatment in an inert atmosphere to obtain porous carbon; and (S3) sequentially performing vapor phase silicon deposition and carbon coating on the porous carbon to obtain the silicon-carbon composite negative electrode material. By adjusting a monomer formula and a secondary curing process in resin synthesis, regulation and control on the hybridization degree of SP3 and SP2 are realized, the crosslinking degree and mechanical strength of the resin are improved, the defects of a porous carbon substrate are reduced, and a silicon-carbon negative electrode material with a certain grain size can be prepared during later-stage deposition; the high performance of the silicon-carbon negative electrode material is maintained, and the silicon-carbon negative electrode material also has higher safety.

The invention discloses a pyrolysis carbonization treatment system for sludge and a carbonization treatment method thereof. The pyrolysis carbonization treatment system comprises a sludge pretreatment device, a multi-section carbonization furnace and a tail gas treatment device which are communicated in sequence, the sludge pretreatment device comprises a plate-and-frame filter press and a paddle dryer which are connected with each other; a combustion-supporting device for receiving drying tail gas and supporting combustion for the multi-section carbonization furnace is arranged at the top of the paddle dryer; the multi-section carbonization furnace comprises a drying layer, a carbonization layer and an activation layer which are communicated from top to bottom, and a steam injector for injecting steam into the activation layer and a combustor for secondarily heating the activation layer are mounted on the outer wall of the multi-section carbonization furnace; compared with the prior art, the separation between the drying tail gas and the sludge is realized through the paddle dryer, the generated drying tail gas is supplied to the multi-section carbonization furnace for combustion under the action of the combustion-supporting device, and the anoxic combustion in the multi-section carbonization furnace is realized under the action of limited sludge gas, so that the carbonization requirement of the sludge in the multi-section carbonization furnace is met; and the sludge in the multi-section carbonization furnace is pyrolyzed, carbonized and activated.

The invention relates to a uniform carbon-coated mesoporous silicon carbon negative electrode material and a preparation method and application thereof.The preparation method comprises the steps that a product obtained after pyrolysis and carbonization of a biomass carbon source is subjected to alkali activation treatment, acid pickling, drying, smashing, passivation, water washing and drying are conducted to obtain a mesoporous carbon matrix, nanometer silicon particles are deposited in pores of the mesoporous carbon matrix, and the uniform carbon-coated mesoporous silicon carbon negative electrode material is obtained. Then selecting a low-temperature carbonization material and polyethylene glycol to perform pre-carbonization and complete carbonization treatment on the mesoporous silicon carbon material to obtain a carbon coating layer, and finally obtaining the uniform carbon-coated mesoporous silicon carbon negative electrode material. When the uniform carbon-coated mesoporous silicon carbon negative electrode material is applied to a lithium battery, the mesoporous skeleton can effectively inhibit volume expansion of silicon in a battery circulation process, and the uniform carbon-coated layer can effectively reduce the risk of direct contact between the negative electrode material and an electrolyte, so that a stable SE I film is formed to reduce the occurrence of side reactions; and the first coulombic efficiency and the cycle performance of the battery are further improved.

The application discloses a kind of high thermal conductivity unidirectional carbon / carbon composite material and preparation method thereof, carbon fiber bundle is spread, carbon fiber bundle is flat, and flat carbon fiber bundle is obtained;Flat carbon fiber bundle is arranged in parallel, and weaving is carried out, and carbon fiber cloth is obtained;Pyrolytic carbon is deposited to carbon fiber cloth;The carbon fiber cloth of pyrolytic carbon deposition is pre-graphitized;Pre-graphitized carbon fiber cloth of preset layer number is laminated, and preform is obtained;Flat carbon fiber bundle is arranged in imitation bricklaying structure;Preform is clamped along the thickness direction, and pyrolytic carbon is deposited to preform densification, then graphitization treatment is carried out, and high thermal conductivity unidirectional carbon / carbon composite material is obtained.The structure and arrangement mode of fiber bundle and unidirectional fiber cloth are controlled and designed, cross-scale structure design on micro-mesoscopic-macro scale is realized, and unidirectional C / C composite material with high thermal conductivity, high bearing and ultra-light is obtained.

The invention relates to a process for treating carbon black, which process comprises gasification of a carbon black-containing feedstock at a temperature of from 730°C to 950°C. The carbon black-containing feedstock is typically pyrolytic carbon black, such as recycled carbon black. It is believed that the resulting treated carbon black has a lower coke content and, as a result, the resulting rubber articles have improved properties.

The application discloses a multi-component carbon fiber reinforced composite material and a low-temperature infiltration preparation method. The reaction infiltration technology is adopted, a low-melting-point infiltrant is used as a carrier, a high-melting-point component is introduced into the C / C composite material at low temperature, different components are enriched in different regions according to the reaction rate difference of each component and pyrolytic carbon, the internal content of the low-melting-point phase is reduced, and the ablation resistance is improved.

The invention belongs to the technical field of lithium ion battery negative electrode materials, and particularly relates to a method for preparing a silicon-carbon composite negative electrode material by using porous carbon jet powder fine powder, which comprises the following steps: (S1) mixing the porous carbon jet powder fine powder and a binder according to a mass ratio of 100: (12-18), and then carrying out curing reaction to obtain a precursor; the binder comprises the following raw materials: petroleum asphalt, a polyamide acid solution, cellulose nanofibers, an epoxy silane coupling agent alcohol-water solution, nickelocene and / or nickel acetylacetonate, and toluene. (S2) after crushing and screening the precursor, performing pyrolysis carbonization in an inert atmosphere to obtain pyrolytic carbon; (S3) activating the pyrolytic carbon under an activation atmosphere condition to obtain a porous carbon material; and (S4) carrying out silane deposition on the porous carbon to obtain the silicon-carbon composite negative electrode material. According to the preparation method, the binder with specific components is adopted, so that the porous carbon airflow fine powder is recycled, and the silicon-carbon composite negative electrode material with excellent electrochemical performance is prepared.

The invention discloses a method and a system for recycling a carbon fiber composite material through step-by-step thermal cracking based on a nitrogen atmosphere, the nitrogen atmosphere is adopted to replace a high-vacuum system, so that the equipment investment and maintenance cost are greatly reduced, meanwhile, the explosion risk caused by air back-suction is effectively prevented through positive pressure protection, and the method and the system are more suitable for industrial amplification; through a two-step method strategy of taking oil at a low-temperature section and removing residues at a high-temperature section, the cracking process is refined, macromolecular oil products are quickly removed under nitrogen carrying by first-stage low-temperature cracking, secondary cracking is effectively inhibited, and first-stage cracked oil which is simpler in component, higher in quality and easy to refine is obtained; long-time high-temperature exposure of the fibers is avoided through step-by-step cracking, decomposition products can be taken away in time through nitrogen flow, deposition of pyrolytic carbon on the surfaces of the fibers is reduced, the fibers with the clean surfaces can be obtained through follow-up short-time oxidation, and the retention rate of the tensile strength of the fibers can reach 90% or above.

The invention discloses a silicon nitride aerogel compounded high-temperature-resistant rigid heat-insulation tile and a preparation method thereof, and belongs to the technical field of heat-insulation tile preparation, and the method comprises the following steps: adding a dispersing agent into pretreated high-temperature-resistant fibers, uniformly dispersing, carrying out vacuum filtration, drying, uniformly mixing with deionized water, pouring into a mold, and freeze-drying to obtain the high-temperature-resistant rigid heat-insulation tile. Carrying out carbon deposition treatment in carbon source gas to deposit pyrolytic carbon on the surface of the green body to obtain a dry green body of the heat insulation tile; and uniformly mixing polysilazane, ferrocene and xylene to obtain a polysilazane precursor solution, and injecting the polysilazane precursor solution into the heat insulation tile dry blank for heat treatment to obtain the silicon nitride aerogel compounded high-temperature-resistant light rigid heat insulation tile. The material has the advantages of strong mechanics, excellent heat insulation, high temperature resistance, oxidation resistance, balanced comprehensive performance, low density and small porosity, and is suitable for the fields of spaceflight, high-temperature equipment and the like. The strength and nucleation are improved by constructing a multi-stage structure and pyrolytic carbon, a binder-free process is green, aerogel is compounded and insulated, and the process is controllable and easy to scale.

The invention belongs to the technical field of thermal structure materials, and particularly discloses a high-temperature-oxidation-resistant carbon fiber reinforced boron nitride-based composite material and a preparation method thereof. According to the carbon fiber reinforced boron nitride-based composite material, the high-temperature oxidation resistant coating made of cracked carbon is formed on the surface of the carbon fiber, the thickness of the high-temperature oxidation resistant coating is reasonably controlled to serve as a reinforcement body, and the density of the reinforcement body is controlled within a reasonable range; according to the coating, the boron nitride matrix and the carbon fibers are uniformly mixed, direct oxidation of the carbon fibers in the coating can be protected and delayed, certain mechanical properties are kept in a high-temperature environment, the strong interaction between the boron nitride matrix and the carbon fibers is reduced, the excellent mechanical properties of the whole material are achieved, and brittle fracture is avoided. Meanwhile, due to the existence of the high-temperature oxidation resistant coating, the skeleton stability of the reinforcement is also guaranteed, the linear ablation rate of the composite material is reduced, and the ablation resistance is improved.

The application discloses a method for recovering graphite from carbon residues of waste lithium ion batteries and regenerated graphite, and relates to the technical field of lithium battery recycling. The carbon residues of waste lithium ion batteries after acid leaching are subjected to heat treatment, in the heat treatment process, the inorganic impurities and organic impurities in the carbon residues can be dissociated into smaller particles, which is convenient for removal in subsequent processes; the pyrolysis carbon residues obtained through heat treatment are subjected to scattering treatment and screening to obtain small particle materials, and the excess large particle impurities are removed; then, through grinding and grading, graphite coarse powder with a particle size Dv50 of 12-15 mu m is obtained, and since the ash impurities are mainly concentrated in the fine powder, the ash can be effectively removed after grading. The heat treatment-scattering, screening-grinding and grading linkage technical means proposed in the application does not need to add additional chemical reagents, but only relies on several physical technical means, which not only can achieve the effect of removing ash impurities, but also can effectively remove amorphous carbon, and the method is simple, easy to operate, safe and environment-friendly.