2085 results about "Chemical vapor deposition" patented technology

The invention discloses a method for preparing a single-layer tungsten diselenide nanoband based on a space confinement strategy. By changing the flow and the growth time of hydrogen, effective control on the width and the thickness of a nanoband can be realized. The method comprises the following steps: uniformly spraying tungsten trioxide powder to one substrate, then covering the substrate by the other substrate, and forming micro reaction space which is of a 'sandwich'-like structure. Growth of a tungsten diselenide nanoband is carried out by utilizing a constant-pressure chemical vapor deposition method; physicochemical characteristics of a one-dimensional transition metal chalcogenide strongly depend on suspension key types on the edge of the one-dimensional transition metal chalcogenide, metallic properties are displayed by an ultranarrow band, and conversion from the metallic properties to semiconductor properties can be displayed from the edge to the center of a wider band; the tungsten diselenide nanoband is widely applied to micro-nano photoelectric devices due to the special property; industrial production of the tungsten diselenide nanoband can be realized through an experimental method of the invention.

Provided herein are methods and apparatuses for reducing line bending when depositing a metal such as tungsten, molybdenum, ruthenium, or cobalt into features on substrates by periodically exposing the feature to nitrogen, oxygen, or ammonia during atomic layer deposition, chemical vapor deposition, or sequential chemical vapor deposition to reduce interactions between metal deposited onto sidewalls of a feature. Methods are suitable for deposition into V-shaped features.

The invention discloses a preparation method of a phosphorus / silicon composite negative electrode material, and belongs to the technical field of lithium battery negative electrode materials. The method comprises the following steps: putting porous carbon into a CVD (Chemical Vapor Deposition) furnace, vacuumizing, heating to 180-230 DEG C, and keeping the temperature for 50-70 minutes; the temperature is increased to 600-800 DEG C, SiH4 silane gas is introduced, cracking deposition is carried out, and the deposition time is 2-3 h; cooling to 300-500 DEG C, introducing a phosphorus source, and permeating into mesopores of 2-50 nm; and cooling the CVD furnace to 260-350 DEG C, and keeping the temperature for 24-72 hours, so that the simple substance is phosphatized into the amorphous red phosphorus nanoparticles. Nanocrystallized phosphorus and silicon are compounded into porous carbon channels, and the characteristic that the lithiation potential of a phosphorus negative electrode is high is utilized, so that the negative electrode is far away from the lithium precipitation potential; meanwhile, the lithiation gram volume of the phosphorus negative electrode is also very high, and the gram volume of the material is not reduced. Silicon is deposited firstly, then phosphorus is deposited, and the silicon is deposited on the innermost side of a pore channel; and expansion in the phosphorus / silicon lithiation process is inhibited by utilizing the confinement of the porous carbon, so that circulation is guaranteed.

The invention discloses a diamond film and a preparation method and application thereof, and the preparation method comprises the steps: taking a substrate material matched with the lattice constant of a diamond film material as a substrate, and carrying out the surface treatment of the substrate; mixed reaction gas comprising 80%-95% of hydrogen, 3%-8% of methane and 2%-12% of auxiliary gas is introduced, wherein the auxiliary gas comprises at least one of argon, chlorine, hydrogen fluoride and hydrogen chloride; carrying out controlled chemical vapor deposition at 850-1000 DEG C under the pressure of not less than 21 kPa, and growing a diamond film on the surface of the substrate; and annealing the diamond film. According to the method, chemical vapor deposition is controlled through cooperation of auxiliary gas and temperature-pressure gradient, and non-corrosion high-speed growth of the high-purity monocrystal diamond film is achieved; in combination with a dynamic annealing process, lattice defects are effectively repaired, the comprehensive performance is optimized, and the reliability of the thin film serving as a heat dissipation component and other applications is remarkably improved.

The invention discloses a graphite piece silicon carbide coating and a preparation method thereof, and belongs to the technical field of inorganic non-metallic materials. The method comprises the following steps: firstly, carrying out surface polishing, cleaning and drying pretreatment on a graphite piece; then a solution containing phosphinazine functionalized silazane and a boron-silicon carlamide compound is adopted for spraying the pretreated graphite piece, drying and curing are conducted, and a surface modification layer is formed; and finally, placing the surface-modified graphite piece in chemical vapor deposition equipment, and depositing at specific temperature, pressure and atmosphere to form the silicon carbide coating. According to the method, uniform nucleation and crystallization of the silicon carbide coating are effectively promoted through unique surface modification treatment, and the compactness and uniformity of the coating and the binding force of the coating and a matrix are remarkably improved. The obtained coating graphite piece has excellent thermal corrosion resistance, oxidation resistance and mechanical property, the service life and the use frequency of the coating graphite piece in semiconductor epitaxial equipment are remarkably prolonged, the whole preparation process is environmentally friendly, and the coating graphite piece is suitable for coating treatment of a large graphite base material.

The invention relates to the technical field of semiconductor etching materials, and provides a method for preparing a high-resistivity silicon carbide material and the silicon carbide material. The method comprises the following steps that a substrate is placed in chemical vapor deposition equipment, the chemical vapor deposition equipment is vacuumized, and then inert gas is introduced; silicon carbon source gas and carrier gas are injected into the chemical vapor deposition equipment through a first gas inlet channel, boron source gas is injected into the chemical vapor deposition equipment through a second gas inlet channel, and silicon carbide is deposited on the surface of the substrate through a chemical vapor deposition process; after gradient annealing is carried out, the substrate is removed; wherein in the step 2, the distance between the air inlet of the first air inlet channel and the air inlet of the second air inlet channel is larger than or equal to 20 cm. According to the method, the doping amount of boron in silicon carbide can be obviously improved, so that the resistivity of silicon carbide is improved, and the etching resistance of silicon carbide is improved.

The invention discloses a method for preparing a hard carbon negative electrode material, the hard carbon negative electrode material and a sodium-ion battery, belongs to the technical field of energy materials, and solves the problems that the existing hard carbon negative electrode material is complex in microstructure and indefinite in sodium storage mechanism, and the traditional preparation method cannot effectively increase the internal closed pore volume, so that the high-platform capacity development is limited, and the sodium-ion battery is difficult to use. And the improvement of the energy density of the sodium-ion battery is restricted. Comprising the following steps: drying and crushing coconut shells; pre-carbonizing the treated coconut shell to obtain a carbonized material; uniformly mixing the carbonized material with an activating agent to obtain a mixed material; carrying out an activation reaction to obtain a biomass-based porous carbon mixed material; washing until the solution is neutral; carrying out activation reaction on the washed material to obtain the biomass-based porous carbon material with high specific surface area and high microporosity; and carrying out variable-temperature chemical vapor deposition reaction to obtain the hard carbon negative electrode material. The method is suitable for a large-scale preparation scene of the hard carbon negative electrode material with abundant closed pores.

The invention provides a silicon carbide trench MOSFET device with a three-side trench structure and a preparation method thereof, and the method comprises the steps: growing a silicon carbide epitaxy on a silicon carbide substrate, and carrying out the injection to form a P-well region; forming a first barrier layer on the P-well region, and performing injection to form a P + region; removing the first barrier layer to form a second barrier layer, and performing injection to form an N + region; removing the second barrier layer, and simultaneously performing rapid thermal annealing on the P-well region, the P + region and the N + region; forming a third barrier layer, and etching to form a gate trench region; removing the third barrier layer, and performing dry-oxygen thermal oxidation to form a gate oxide layer; forming polycrystalline silicon by using chemical vapor deposition; after the polycrystalline silicon is doped, etching is carried out to form a grid electrode; and depositing metal to form a drain electrode and a source electrode, and performing rapid thermal annealing on the drain electrode and the source electrode to form ohmic contact. By arranging the three-side groove structure, the area of the channel is increased, and conduction resistance is reduced.

The invention relates to the technical field of lithium ion batteries, in particular to a silicon-carbon negative electrode material and a preparation method thereof. The preparation method of the silicon-carbon negative electrode material comprises the following steps: carrying out liquid-phase coating treatment on a porous carbon material and a fast ion conductor precursor to form a porous carbon material coated with a fast ion conductor so as to prepare a modified porous carbon material; carrying out first chemical vapor deposition treatment by taking silane gas as a deposition precursor, and depositing nano silicon on the surface of the modified porous carbon material to prepare a silicon-carbon core; and carrying out secondary chemical vapor deposition treatment by taking a soft carbon gas source as a deposition precursor in an inert gas atmosphere, and depositing nano soft carbon on the surface of the silicon-carbon inner core to prepare the silicon-carbon negative electrode material. The preparation method of the silicon-carbon negative electrode material solves the technical problem that the electrochemical performance of the silicon-carbon material is poor due to the fact that the volume of the existing silicon material is expanded and the ionic conduction performance is reduced by a carbon coating technology.

The utility model provides an isolation structure and a chemical vapor deposition device, the isolation structure is arranged in a reaction cavity of the vapor deposition device, a heating device is arranged in the reaction cavity, the reaction cavity comprises a first annular cover, a second annular cover and a third annular cover, the first annular cover comprises a first space used for accommodating the heating device, and the second annular cover comprises a second space used for accommodating the heating device; the second annular cover is arranged on the first annular cover in a sleeving manner; the ring width of the second annular cover is larger than that of the first annular cover, so that a cavity is formed between the first annular cover and the second annular cover. The isolation structure blocks a flowing path of reaction gas in the reaction cavity, and corrosion of the reaction gas to the radio frequency induction coil and the bottom wall of the reaction cavity is reduced; and meanwhile, the radiation heat dissipation of the wafer tray on the radio frequency induction coil is isolated, so that the temperature influence of thermal radiation on the radio frequency induction coil is weakened, and the uniformity of thin film deposition is improved.

The invention relates to the technical field of electrolytic copper foil processing, printed circuit board processing and electrolytic copper foil, in particular to a preparation method of a bi-component stripping layer carrier copper foil and the bi-component stripping layer carrier copper foil. The preparation method provided by the invention comprises the following steps: preparing a carrier copper layer; preparing a first inorganic stripping layer on the smooth surface of the carrier copper layer through an electrochemical / physical vapor deposition method; preparing a second inorganic stripping layer on the surface of the first inorganic stripping layer through a low-temperature chemical vapor deposition method; preparing an ultra-thin copper layer on the surface of the second inorganic stripping layer through a pulse electrochemical deposition method; carrying out roughening treatment on the ultra-thin copper layer; and constructing a non-copper functional layer on the surface of the roughened ultra-thin copper layer, and carrying out silane coupling agent coating treatment to obtain the double-component stripping layer carrier copper foil. The two-component inorganic matter is used as the stripping layer of the carrier copper foil, the heat resistance of the stripping layer of the carrier copper foil is improved, and meanwhile the stability of the separating force between the ultra-thin copper layer and the carrier copper layer is improved.

The invention belongs to the technical field of photoelectric detection, and discloses a molybdenum ditelluride / nickel ditelluride heterojunction-based photoelectric detector and a preparation method and application thereof, and the molybdenum ditelluride / nickel ditelluride heterojunction-based photoelectric detector is prepared by stripping single crystal molybdenum ditelluride onto an oxide layer silicon substrate through a mechanical stripping method to obtain a molybdenum ditelluride nanosheet; a nickel ditelluride nanosheet is obtained through a chemical vapor deposition method; the molybdenum ditelluride nanosheet is transferred to the nickel ditelluride nanosheet through a PVA dry transfer method to form an overlapped part, and a molybdenum ditelluride / nickel ditelluride heterojunction is formed; and preparing electrodes at two ends of the molybdenum ditelluride / nickel ditelluride heterojunction through electron beam evaporation or thermal evaporation. The photoelectric detector utilizes a built-in electric field generated by a two-dimensional material heterojunction interface to effectively improve the photoelectric conversion efficiency and response speed of a visible light wave band.

The invention provides a multiband photoresponse nerve synapse device based on a two-dimensional and organic heterostructure, an array and application, and belongs to the technical field of organic electric solid-state devices. The device provided by the invention adopts a three-end bottom gate top contact structure and comprises a gate substrate, an insulating layer, a channel layer and a source / drain electrode, and the channel layer forms an II-type heterojunction by a two-dimensional semiconductor material with a narrow-band gap characteristic and an organic semiconductor material. The heterostructure realizes ultraviolet to far infrared (365nm-10 [mu] m) multiband photoelectric response, and shows synaptic plasticity under light pulse modulation, including short-term enhancement, long-term enhancement and learning-forgetting-re-learning characteristics. Large-area array preparation of the device can be realized through methods such as chemical vapor deposition, solution spin coating, jet printing or layer-by-layer self-assembly. The technology not only can be used for brain-like learning and memory simulation, but also can be applied to the fields of sensing and memory integrated intelligent systems, optical neural networks, artificial vision, multi-mode intelligent sensing and the like.

The invention discloses a preparation method and application of a zinc-bromine flow battery positive electrode material, and belongs to the field of zinc-bromine flow batteries. The preparation method comprises the following steps: firstly, cleaning and activating a carbon-based three-dimensional conductive network substrate by adopting plasmas, performing oxygen / argon plasma etching, and performing chemical vapor deposition on carbon to prepare three-dimensional porous carbon; then growing a metal oxide nanocrystalline array on the three-dimensional porous carbon by a hydrothermal method, and carrying out ammonia gas calcination to convert the metal oxide nanocrystalline array into a metal nitride nanocrystalline array; then preparing an electro-deposition solution containing tin bismuth salt and an aniline-bromine source polymerization solution, and constructing Sn-Bi bimetallic nanoparticles and a polyaniline-bromine complex layer on the metal nitride nanocrystalline array / three-dimensional porous carbon precursor through electro-deposition and electro-polymerization in sequence to finally prepare the high-performance zinc-bromine battery positive electrode material. The positive electrode material has high conductivity, excellent Br2 / Br <-> catalytic activity and structural stability, and the coulombic efficiency, the voltage efficiency and the energy efficiency of the battery are remarkably improved.

The invention discloses a preparation method of a high-conductivity and low-thermal-conductivity carbon-carbon composite material electrode, and relates to the technical field of electrode preparation, the preparation method comprises the following steps: mixing nano carbon spheres, an organic binder and a solvent to obtain a mixed slurry, respectively coating the mixed slurry on a PAN-based carbon fiber web and pitch-based carbon fiber non-woven cloth, and drying to obtain the high-conductivity and low-thermal-conductivity carbon-carbon composite material electrode. Then preparing a preform by alternately laying and needling the PAN-based carbon fiber web coated with the mixed slurry and pitch-based carbon fiber non-woven cloth, pretreating the preform by adopting a chemical vapor deposition technology to obtain an intermediate I, and treating the intermediate I in a pressure impregnation tank and a carbonization and graphitization furnace to obtain an intermediate II; and carrying out pressure impregnation-carbonization treatment on the intermediate II to obtain the carbon / carbon composite material. According to the preparation method of the high-conductivity and low-heat-conductivity carbon-carbon composite material electrode, the material has high conductivity and low heat conductivity, a carrier is provided for precise heat management under specific conditions in a high-temperature furnace, and the energy consumption of equipment is reduced.

The invention provides a heterojunction quantum well and a preparation method thereof, and the method comprises the steps: providing a substrate, and forming a heterojunction quantum well at one side of the substrate through a chemical vapor deposition method; the heterojunction quantum well comprises a first barrier layer, a quantum well layer and a second barrier layer which are stacked in sequence, the first barrier layer is located between the quantum well layer and the substrate, the first barrier layer and the second barrier layer are both made of germanium-silicon, when the heterojunction quantum well is a silicon heterojunction quantum well, the quantum well layer is a silicon quantum well layer, and when the heterojunction quantum well is a silicon quantum well layer, the second barrier layer is a silicon quantum well layer. When the heterojunction quantum well is a germanium heterojunction quantum well, the quantum well layer is a germanium quantum well layer; in the process of forming the heterojunction quantum well, the precursor is decomposed in a target temperature range, and a product obtained through decomposition is deposited on one side of the substrate to obtain the heterojunction quantum well; the precursor is subjected to multi-stage reaction during decomposition, and the target temperature range is 300-550 DEG C; the interface quality of the heterojunction quantum well can be greatly improved, the surface roughness of the film layer can be reduced, and high-quality preparation of the heterojunction quantum well is realized.

The invention discloses a high-valued utilization method of waste biomass, which comprises the following steps: firstly, applying current to the waste biomass containing carbon element to generate Joule heat, and generating a high-temperature environment in an extremely short time, so as to realize rapid carbonization of the biomass; then conductive carbon black or other auxiliaries do not need to be additionally added, current is applied again to generate Joule heat, a higher-temperature environment is generated within an extremely short time, and graphitization transformation of the biochar is achieved. Compared with traditional pyrolysis, hydrothermal, roasting or chemical vapor deposition methods, the flash Joule thermal method has the advantages of being easy and convenient to operate, short in consumed time, low in energy consumption, high in efficiency, high in safety, environmentally friendly and the like, and is suitable for high-value utilization of various biomass resources and green preparation of graphene materials.

The invention relates to an oxychloride gate dielectric material and a preparation method and application thereof. The preparation method comprises the following steps: respectively placing a chloride precursor and a substrate material at the bottom and a single-side opening of a same reaction container with a single-side opening, and placing the reaction container with an opening at one side in a chemical vapor deposition device, with the opening positioned at one side of a vent in the chemical vapor deposition device, regulating the relative humidity of the reaction chamber, and depositing on the surface of the substrate material to obtain the oxychloride gate dielectric material. According to the invention, a chemical vapor deposition preparation process is adopted to control and obtain the oxychloride gate dielectric material with controllable and uniform morphology, so that the problems of random shape and non-uniform morphology of the oxychloride gate dielectric material in the chemical vapor deposition process are solved, the controllable growth of the material is realized, and the material has a high dielectric constant; the material also has an atomic-scale flat surface and is applied to a transistor device and / or a capacitor device, and the device has higher performance.

The invention relates to the technical field of semiconductor material preparation, and provides a TaC composite coating process based on a carbon nanostructure transition layer and a product thereof. The method comprises the following steps: a) pretreating the surface of a base material to form a groove, b) introducing a carbon source gas, carrying out first chemical vapor deposition under the action of a metal salt catalyst to grow carbon nanoparticles, and depositing the base material pretreated in the step a) to obtain a transition layer deposition base material, c) gasifying a tantalum source, mixing the gasified tantalum source with the carbon source gas, a reaction gas and a carrier gas, and carrying out second chemical vapor deposition to obtain the transition layer deposition base material. And second chemical vapor deposition is conducted, the transition layer deposition base material is filled with the fine grain particle layer, then deposition continues to be conducted on the surface of the transition layer deposition base material to form the coarse grain particle layer, and finally the TaC composite coating is obtained. According to the method, the compactness of the coating can be improved, the bonding strength of the coating and the base material is enhanced, the performance of the TaC composite coating is improved, the service life of the TaC composite coating is prolonged, and the reliability of the TaC composite coating is improved.

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 provides a preparation method of a PdSe2 / Bi2O2Se Van der Waals heterojunction self-driven photoelectric detector, and relates to construction of a two-dimensional material heterostructure and application of the two-dimensional material heterostructure to a photoelectric device. The method comprises the following steps; the preparation method comprises the following steps: preparing nanosheets through a chemical vapor deposition (CVD) process; respectively preparing a PdSe2 nanosheet and a Bi2O2Se nanosheet by adopting the CVD process; and preparing a heterostructure: transferring the PdSe2 nanosheet to the surface of the Bi2O2Se nanosheet in a dry transfer mode to form a Van der Waals heterojunction structure with a clean interface and tight interlayer coupling. The transfer technology keeps the lattice and morphology of the two-dimensional material complete, and reduces organic residues and solvent pollution influences. The heterojunction structure is combined with the narrow band gap of PdSe2 and the broad spectrum response characteristic of Bi2O2Se, and efficient photoelectric conversion from visible light to near-infrared light is achieved. And an electric field is built in the p-n type heterojunction, so that the device is self-driven without external bias voltage, and has the performance of low power consumption and the like. And the method is low in process thermal budget, high in compatibility and suitable for various substrates, and a technical path is provided for construction of the flexible photoelectric detector.

The invention belongs to the technical field of preparation of single-walled carbon nanotube fibers, and particularly relates to a preparation method of high-conductivity single-walled carbon nanotube fibers, which comprises the following steps: preparing a single-walled carbon nanotube crude product by a chemical vapor deposition method, pickling and purifying, and oxidizing and purifying at high temperature to obtain a single-walled carbon nanotube; the preparation method comprises the following steps: adding a single-walled carbon nanotube into a poly [2, 5-dihydroxy-1, 4-phenylene pyridine diimidazole] aqueous solution, dispersing, and collecting supernatant liquid to obtain a single-walled carbon nanotube purified liquid; adding chlorosulfonic acid into the single-walled carbon nanotube purified solution in an argon atmosphere to obtain a single-walled carbon nanotube spinning solution; and injecting the single-walled carbon nanotube spinning solution into a coagulating bath in an argon atmosphere to prepare the single-walled carbon nanotube fiber. According to the invention, the poly [2, 5-dihydroxy-1, 4-phenylenediimidazole] is adopted to selectively disperse the metallic single-walled carbon nanotubes, and the gold single-walled carbon nanotubes in the single-walled carbon nanotube fibers are high in purity, so that the conductivity can be improved.

The invention relates to the technical field of preparation of single-walled carbon nanotubes, in particular to a chemical vapor deposition reactor, an FCCVD reaction device and a batch continuous preparation method of single-walled carbon nanotubes. By optimizing the structure of the reactor, the flow field in the reactor is further optimized, uniform distribution of gas is realized, and in-situ growth of catalyst particles and uniformity of the particle size are maintained. Results of the embodiment show that the reaction process is strengthened through optimization design of the reactor, batch continuous preparation of the single-walled carbon nanotubes can be achieved, the utilization efficiency of the catalyst is greatly improved, the yield of the unit catalyst is greatly improved, and the prepared SWCNT is high in quality.

The invention provides improved techniques for bonding devices using copper-to-copper or other types of bonds. A substrate is cleaned to remove surface oxides and contaminants and then rinsed. The rinsed substrate is provided to coating unit where a protective coating is applied to the substrate. The protective coating may be applied by immersing the substrate in a bath or via chemical vapor deposition. In an aspect, the protective coating may be copper selective so that the protective coating is only applied to copper features of the substrate. The protective coating minimizes formation of oxides and other bond weakening forces that may form during bonding processes, such as bonding a copper wire to a copper bond pad of the substrate. In an aspect, an annealing process is used to cure the protective coating and remove small imperfections and other abnormalities in the protective coating prior to the bonding process.

The invention belongs to the technical field of electronic packaging carrier plates, and discloses an ultrathin diamond carrier plate and a preparation method and application thereof.The preparation method comprises the steps that a heterogeneous substrate is selected, cleaned and subjected to seed crystal, and then a sacrificial layer is introduced; growing a compact and continuous ultrathin diamond film on the substrate pretreated in the step 1 through chemical vapor deposition; sequentially carrying out surface cleaning, activation and modification on the diamond film; constructing a metal layer structure required by conductive wiring and a heat dissipation substrate on the surface of the diamond carrier plate; the ultrathin diamond film deposited on the heterogeneous substrate is separated from the substrate, and a self-supporting diamond carrier plate is obtained; the heat-conducting property of the packaging substrate is remarkably improved, and an ultrathin structure with controllable thickness can be prepared; a reliable diamond film heterogeneous substrate growth and stripping process is provided, so that an independent support plate can be conveniently obtained from a growth substrate by the thin film; the metallization adhesive force of the surface of the carrier plate is enhanced, high-density circuit patterning on the surface of the substrate is supported, and the packaging reliability is improved.

The invention discloses an all-chemical vapor deposition preparation method of a carbon-carbon heater with the density of 1.6-1.8 g / cm < 3 >, and belongs to the technical field of carbon-carbon heater preparation. The scheme comprises the following steps: 1) preparing a carbon fiber preform with the volume density of 0.5 + / -0.03 g / cm < 3 > by adopting a needling process; 2) taking natural gas as a carbon source, taking low-molecular mixed hydrocarbon gas as auxiliary gas, and performing densification treatment on the carbon fiber preform by adopting an all-chemical vapor deposition method in a nitrogen or argon atmosphere; and (3) carrying out high-temperature graphitization treatment on the densified preform, and sleeving a graphite tool into the heater for fixing in the treatment process, so as to prepare the carbon-carbon heater with the density of 1.6-1.8 g / cm < 3 >. The carbon-carbon heater prepared by the preparation method has the characteristics of stable heat supply, no resistance fluctuation, good corrosion resistance, long service life, short preparation period and the like.

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 discloses a FeNi-C-CNTs-carbon fiber composite material and a preparation method and application thereof, and the preparation method comprises the following steps: (1) cutting carbon fibers into short fibers, dispersing the short fibers into fiber bundles, fixing the fiber bundles, and carrying out electrostatic dispersion; (2) spraying an adhesive on the surface of the dispersed carbon fiber to form an adhesive layer on the surface of the carbon fiber, and then pre-curing the adhesive; and (3) carrying out chemical vapor deposition by adopting a horizontal tube furnace and taking a mixture of ferric acetylacetonate and nickel acetylacetonate as a metal precursor. In the FeNi-C-CNTs-carbon fiber composite material, the FeNi alloy nanoparticles and the carbon nanotubes cooperatively construct a three-dimensional conductive network, wave absorbing mechanisms such as magnetic loss, dielectric loss and multiple scattering are strengthened by means of the unique structure, the wave absorbing performance is remarkably improved, the effective frequency band is widened, and the composite material has excellent microwave absorbing performance and structural stability.

The invention discloses a method for preparing a single-walled carbon nanotube, and belongs to the technical field of single-walled carbon nanotubes. When the single-walled carbon nanotube is prepared, the single-walled carbon nanotube is grown by using a chemical vapor deposition method; then, the grown single-walled carbon nanotubes are subjected to acid pickling, then, the carbon tubes are sorted and purified by adopting a polymer dispersant, and finally, the polymer dispersant is removed to obtain the single-walled carbon nanotubes; the polymer dispersant disclosed by the invention is obtained by reacting an aldehyde-terminated fluorenyl surfactant with diamino dipyridyl; wherein the aldehyde-terminated fluorenyl surfactant is obtained by polymerizing 9, 9-di-n-octylfluorene-2, 7-diboric acid di-pinacol ester and quaternary ammonium salt containing 2, 7-dibromofluorene, and then reacting with 5-formyl-2-thiopheneboronic acid pinacol ester for end capping; the prepared single-walled carbon nanotube is relatively high in purity and relatively high in finished product conversion rate.

The invention belongs to the technical field of hard alloy surface engineering, and particularly relates to an MT-TiCN gradient coating of a hard alloy cutter and a preparation method of the MT-TiCN gradient coating. The coating sequentially comprises a TiN bottom layer, an MT-TiCN gradient layer, a transition layer and an Al2O3 layer from inside to outside, wherein the C / N atomic proportion of the MT-TiCN gradient layer is in gradient distribution from rich N to rich C in the thickness direction. The coating is prepared through a medium-temperature chemical vapor deposition process, the internal stress of the coating is effectively relieved, and the bonding strength, toughness and wear resistance of the coating and a matrix are remarkably improved.