181 results about "Graphite substrate" patented technology

The invention belongs to the technical field of semiconductors, and particularly relates to a gradient transition composite tantalum carbide coating and a preparation method thereof.The gradient transition composite tantalum carbide coating is located on the surface of a graphite substrate material and sequentially comprises a pyrolytic carbon coating, a tantalum carbide-pyrolytic carbon composite coating and a tantalum carbide coating from inside to outside; wherein the thermal expansion coefficient of the pyrolytic carbon coating is 2.5-4.5 * 10 <-6 > / K, the thermal expansion coefficient of the composite coating is 4.5-6.0 * 10 <-6 > / K, and the thermal expansion coefficient of the tantalum carbide coating is 6.1-8.0 * 10 <-6 > / K. According to the gradient transition structure of the coating, the problem that thermal expansion coefficients between the coating and a base body are not matched is solved, the thermal shock resistance of the coating is effectively improved, meanwhile, the pinning effect can be achieved, the adhesive force between the coatings is enhanced, and the service life of a product is prolonged; compared with a single tantalum carbide coating, crack accumulation and through holes cannot be generated.

The preparation method comprises the following steps: brushing ultrahigh-temperature ceramic oxide slurry on the surface of a graphite base material, carrying out first heat treatment to obtain a porous transition layer, then brushing ultrahigh-temperature carbide slurry on the surface of the porous transition layer, and carrying out second heat treatment to obtain the high-temperature-stable and corrosion-resistant multi-layer composite ceramic coating on the surface of the graphite base material. The preparation method comprises the following steps: performing primary heat treatment on the surface of an ultra-high-temperature carbide layer, drying to obtain the ultra-high-temperature carbide layer, performing roughening treatment on the surface of the ultra-high-temperature carbide layer by adopting ultra-high-temperature carbide slurry, performing secondary heat treatment to obtain a rough carbide layer, and performing point pressure on the surface of the rough carbide layer by adopting metal carbide ceramic mixed slurry to obtain dense bulges; according to the method disclosed by the invention, not only can the bonding firmness among the layers be remarkably improved, but also the situation that the graphite base material and the surface protection layer react at high temperature, so that the coating fails and falls off is effectively avoided, the use limit of the protection layer is further enhanced, and the method has a wide application prospect.

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 belongs to the technical field of ultrahigh-temperature ceramic materials, and discloses a high-purity porous tantalum carbide ceramic and a preparation method and application thereof.The preparation method comprises the steps that a porous graphite substrate is horizontally placed in a vertical vapor deposition chamber, after the chamber is vacuumized, argon is introduced, the reaction air pressure is increased to 10-100 mbar, and the graphite substrate is heated to the deposition temperature of the tantalum element; inorganic tantalum salt and hydrogen are conveyed into the cavity, and tantalum element deposition of the first area is achieved; argon is introduced into the reaction chamber, the reaction air pressure is pressurized, the carrier gas flow of the inorganic tantalum salt is increased, the deposition temperature of the tantalum element is increased, tantalum element deposition of the second area is achieved, and the process is repeated to achieve sequential deposition of the tantalum element on the porous graphite substrate from inside to outside; after the tantalum element is completely deposited, the high-purity porous graphite substrate is heated and reacts to obtain tantalum carbide, reaction conditions are adjusted, so that reaction airflow gradually permeates at different depths of the porous material, and Ta is uniformly deposited at different positions.

The invention relates to a method for enhancing the dispersibility of a graphite aqueous solution by using an anionic composite surfactant based on molecular dynamics simulation, which comprises the following steps: establishing an initial model, introducing graphite unit cells, and constructing water molecules and anionic surfactant molecules; performing energy minimization operation on the initial model, and performing geometric optimization on the initial model; establishing an intermediate model, wherein the intermediate model comprises a graphite substrate model, an anionic composite surfactant overall model and a water molecule overall model; combining the intermediate models to form a graphite / anionic composite surfactant / water interface model; carrying out geometric optimization on the graphite / anionic composite surfactant / water interface model; selecting a proper interatomic interaction potential function, and setting proper simulation parameters and steps so as to perform molecular dynamics simulation on the final interface model; and obtaining dynamic information of the interface model. The method has the beneficial effects that the operation is simple, the cost is low, the precision is high, and the optimization of the formula of the composite surfactant is facilitated.

The invention provides a silicified graphite material, a silicified graphite casting mold and a preparation method of the silicified graphite casting mold, and relates to the technical field of nickel-based high-temperature alloy and titanium alloy casting. The silicified graphite material provided by the invention comprises a porous graphite matrix and a silicon carbide layer wrapping the surface of the porous graphite matrix, the porous graphite substrate has a hierarchical porous structure, the hierarchical porous structure comprises closed holes and penetrating holes, the aperture of the closed holes is 0.001-0.05 mm, the penetrating holes penetrate through the porous graphite substrate, and the penetrating holes comprise first-level penetrating holes with the aperture of 0.03-0.2 mm and second-level penetrating holes with the aperture of 0.1-1 mm; and the silicon carbide layer uniformly wraps the external surface of the hierarchical porous graphite matrix and the surfaces of the internal through holes. The silicified graphite material not only has good thermal stability and thermal conductivity, but also has good high-temperature oxidation resistance, good corrosion resistance, high mechanical strength, excellent air permeability and good dimensional stability.

The invention provides a deposition method and system for chemical vapor deposition of silicon carbide, and the method comprises the following steps: S1, providing a graphite base material, putting the base material into a reaction module, starting a rotating device, introducing silane gas, controlling the reaction temperature to be 1100-1200 DEG C, and continuously reacting for 5-10 minutes to form silicon carbide grains on the surface of the base material; s2, the temperature of the reaction module is lowered to 400-500 DEG C, annealing treatment is conducted on the base material with the silicon carbide crystal grains formed on the surface, the reaction time is not shorter than 5 min, and the flatness of the silicon carbide crystal grains is improved; and S3, the gas supply module introduces at least three kinds of process gas into the reaction module, the temperature of the reaction module is adjusted to rise to 1300-1500 DEG C, and the silicon carbide film is deposited on the surface of the base material. Through annealing treatment, the flatness of silicon carbide grains is remarkably improved, the deposition efficiency of the silicon carbide thin film is optimized, internal stress generated in the deposition process is effectively reduced, the uniformity and consistency of a deposition layer are ensured through application of the rotating device, and the overall quality of the silicon carbide thin film is further improved.

The invention provides a 1500-DEG C thermal shock and oxidation resistant plasma spraying method for a Si coating on the surface of graphite, coating graphite and application. The method comprises the following steps that the to-be-sprayed surface of a graphite matrix is pretreated; spraying the to-be-sprayed surface by adopting a plasma spraying technology to obtain a Si coating on the to-be-sprayed surface; carrying out heat treatment on the graphite matrix with the Si coating in a vacuum environment by adopting a vacuum heat treatment technology, so that part of solid silicon in the Si coating is molten into liquid silicon or silicon steam, and the liquid silicon or silicon steam permeates into the graphite matrix containing air holes under the action of capillary tubes, so that part of liquid silicon or silicon steam and the graphite matrix are subjected to chemical reaction; and thus, the gradient transition Si / SiC coating is obtained through in-situ growth on the to-be-sprayed surface of the graphite matrix. According to the method provided by the invention, the problem that a traditional method for spraying the Si coating on the surface of the graphite in a plasma manner cannot be used in an environment of 1500 DEG C is solved.

The invention belongs to the technical field of silicon carbide coatings, and particularly relates to a method for quickly depositing a silicon carbide coating through CVD (Chemical Vapor Deposition), which comprises the following steps: pretreating a graphite substrate; debugging the equipment; placing the pretreated substrate in a reaction furnace, closing a furnace door, starting a vacuum system, pumping the pressure in the reaction furnace to-Pa, and reducing the interference of air in the furnace on the reaction; introducing a small amount of hydrogen into the reaction furnace, rapidly raising the temperature in the furnace to 800-900 DEG C, maintaining the temperature, then introducing a very small amount of silicon source and carbon source gas, and carrying out preliminary deposition on the surface of the substrate; and hydrogen, silicon tetrachloride and methane are sequentially introduced. The preparation method of the CVD silicon carbide coating can solve the problems of low deposition rate, long preparation period and the like when the existing CVD process is used for preparing the silicon carbide coating, so that the production efficiency can be greatly improved, the cost can be reduced, and the preparation method has important significance in promoting the application of the silicon carbide coating in more fields.

The invention discloses a method for preparing a carbide coating with high bonding strength on a graphite surface. The method comprises the following steps: roughening the graphite surface to obtain roughened graphite, coating transition layer slurry on the roughened graphite surface, performing first sintering to obtain a transition layer, coating surface layer slurry on the transition layer surface, and performing second sintering to obtain the carbide coating. According to the preparation method, the synergistic effect of chemical bonding and mechanical embedding is achieved by optimizing the surface roughness, designing the transition layer and sintering the carbide coating, the carbide coating with the high interface bonding force is prepared on the graphite surface, and the preparation method is suitable for surface modification of graphite-based materials under the harsh working conditions of high temperature, high corrosion and the like.

The utility model discloses an electric heating body with graphite as a substrate, which comprises a graphite substrate, an insulating heat conduction coating is arranged on the outer surface of the graphite substrate, and an electrified heating layer is arranged on the outer surface of the insulating heat conduction coating. According to the electric heating body, the graphite with excellent heat-conducting property is used as the substrate, and the insulating heat-conducting coating is additionally arranged between the outer surface of the graphite and the electric heating layer in order to be matched with the electric heating layer for use, so that heat generated by the electric heating layer is quickly transferred to the graphite through the insulating heat-conducting coating to realize quick heating, and the electric heating body is high in heat efficiency; and the electrified heating layer is separated from a heated substance (such as water) by the graphite and the insulating heat-conducting coating, so that the heated substance is separated from electricity, such as water-electricity separation, the use is safer, and in addition, the graphite is easy to form a gasification core in the heating process, so that boiled water is continuously discharged.

The invention provides a composite carbon layer coated graphite matched silicon carbon material and a preparation method thereof, and the preparation method comprises the following steps: coating asphalt on a graphite base material to obtain coated graphite; introducing a carbon source gas to carry out chemical vapor deposition on the coated graphite, and generating a graphite nano bridging structure with specific orientation on the surface of the coated graphite to obtain modified graphite; and preparing a silicon-carbon base material, and mixing the silicon-carbon base material with the modified graphite to obtain the composite carbon layer coated graphite matched silicon-carbon material. By constructing the graphite nanometer bridging structure and the carbon layer, the synchronous transmission efficiency of electrons and lithium ions is improved, the resistance is reduced, and the charging and discharging efficiency of the battery is improved. By introducing the silicon-carbon base material, the lithium storage capacity of the material is remarkably improved, and the charge-discharge capacity of the battery is improved. The graphite nanometer bridging structure and the porous carbon layer structure enhance the structural stability of the material, reduce material pulverization and capacity fading caused by silicon volume expansion, and prolong the service life of the battery.

The invention discloses a preparation method of a SiC coating graphite base transition layer. The technical problems that in the prior art, the bonding force between a SiC coating and a graphite base is insufficient, and the compactness of the coating is poor are solved. The method comprises the following steps: gradient functionalization pretreatment: carrying out plasma microcosmic roughening treatment and organosilicon compound dipping-pyrolysis-nitriding treatment on a graphite base to form a Si-C-O-N functionalized transition layer; multi-stage pulse chemical vapor deposition is carried out, low-temperature seed layer deposition, medium-temperature growth layer deposition and high-temperature densification layer deposition are carried out in three stages, and different pulse periods and precursor combinations are adopted; in-situ plasma auxiliary treatment is conducted, and plasma treatment is conducted at the deposition stage interval and after the final stage is completed. Strong interface combination of the graphite substrate and the SiC coating is achieved through unique gradient functionalization pretreatment, the coating density is improved through the multi-stage pulse CVD technology, the performance of the SiC coating graphite base in semiconductor processing and high-temperature plasma environments is remarkably improved, and the service life of the SiC coating graphite base in the semiconductor processing and high-temperature plasma environments is remarkably prolonged.

The present invention belongs to the technical field of composite silicon-based negative electrode materials and discloses a composite silicon-based negative electrode material, a preparation method, and a solid-state battery. The composite silicon-based negative electrode material comprises a graphite substrate and silicon carbide nanowires and nanosilicon particles attached to the surface of the graphite substrate. The silicon carbide nanowires are interwoven to form a network structure, and the nanosilicon particles are dispersed in the network structure. The nanosilicon particles are dispersed in the network of interwoven silicon carbide nanowires, presenting a porous structure similar to that of reinforced concrete. The porous structure provides space for volume expansion, mitigating damage to the electrode structure caused by volume expansion during lithium insertion and extraction of the silicon-based negative electrode. At the same time, the one-dimensional silicon carbide therein, due to its high mechanical strength, can mitigate damage to the electrode structure caused by long-term cycling of the silicon negative electrode, thereby improving the mechanical properties of the silicon negative electrode and thus improving the cycling performance of the silicon electrode.

The invention relates to a novel silicon-carbon material and a preparation method and application thereof, the silicon-carbon material comprises a graphite substrate, a silicon layer coating the outer surface of the graphite substrate and a silicon carbide layer coating the outer surface of the silicon layer, and a graphite-silicon-silicon carbide three-layer composite structure is formed; wherein the silicon layer and the silicon carbide layer are formed by one-time continuous deposition through a chemical vapor deposition process; the silicon carbon material is applied to a negative electrode material of a lithium ion battery. According to the novel silicon-carbon material as well as the preparation method and the application thereof, a single chemical vapor deposition process is adopted, and selective deposition of a silicon material and a silicon carbide material is realized by accurately regulating and controlling the hydrogen content in a deposition atmosphere on the premise of not changing equipment and raw materials; according to the method, the novel silicon carbon material with the SiC coated silicon structure (SiC coated Si / G) is successfully prepared.

The invention provides an inner hole plasma spraying high-bonding-strength bonding layer and Y2O3 coating material and a preparation technology thereof. The bonding layer comprises a middle transition layer formed after Si and C on the surface of a graphite matrix are subjected to a chemical reaction. The inner hole plasma spraying high-bonding-strength bonding layer provided by the invention is composed of a silicon carbide transition layer generated by in-situ reaction of molten silicon and carbon on the surface of a graphite matrix, and can form a Si-O-M bridged bond with a subsequent ceramic coating, so that interface bonding is converted into chemical bonding from mechanical anchoring, and the bonding strength is improved. And meanwhile, by utilizing the thermal expansion characteristic of silicon carbide between graphite and ceramic, the purposes of buffering thermal mismatch stress step by step on the atomic scale, blocking high-temperature diffusion of carbon elements and endowing the coating with lasting high bonding strength and thermal cycling stability are achieved.

The invention discloses an interpenetrating network structure tantalum carbide composite coating as well as a preparation method and application thereof, and relates to the technical field of graphite materials. Comprising the following steps: 1, preparing a carbide coating with an interpenetrating network structure on a graphite substrate; 2, cleaning and drying the carbide coating with the interpenetrating network structure, mixing inorganic tantalum salt, alkane and hydrogen according to the molar ratio of (2-5): (2-5): (1-2) in an inert atmosphere by taking argon as carrier gas, and then carrying out CVD (Chemical Vapor Deposition) under the conditions that the pressure of the mixed gas is 5-100 mbar, the deposition temperature is 1000-1800 DEG C and the deposition time is 6-10 hours to obtain the interpenetrating network structure carbide coating. The yield of the TaC coating is improved, the binding force of the coating and a substrate material is improved, and cracking of the coating is reduced.

The invention discloses a composite material and a preparation method thereof, an electrode and a battery, and relates to the technical field of new energy. The composite material comprises a graphite matrix, a first coating carbon layer coating the graphite matrix, and a second coating carbon layer coating the first coating carbon layer, wherein the material of the first carbon coating layer comprises carbon nanotubes, and the material of the second carbon coating layer comprises biomass carbon source derived carbon, zeolite imidazate framework material derived carbon and resin derived carbon. The composite material provided by the embodiment of the invention has relatively high conductivity.

The invention relates to the technical field of semiconductor material preparation, and provides a method for improving the interface bonding strength of a SiC coating on the surface of a graphite base material and a product thereof. The method comprises the following steps: S1, placing a graphite base material in a carbon nanotube suspension, and forming a carbon nanotube coating layer on the surface of the graphite base material by adopting an electrophoresis method; s2, the graphite base material treated in the step S1 is placed in chemical vapor deposition equipment, the chemical vapor deposition equipment is vacuumized, and then the deposition equipment is cleaned with inert gas; and S3, mixed gas of silicon carbon source gas, reaction gas and carrier gas is introduced into chemical vapor deposition equipment, and the SiC coating is deposited on the surface of the carbon nanotube coating layer by adopting a chemical vapor deposition process. According to the method, the interface bonding force between the silicon carbide coating and the graphite substrate can be increased, so that the subsequent silicon carbide coating is not easy to peel off in the use process, and the service life and the reliability of the silicon carbide coating material are improved.

A field emission (FE) cathode for a vacuum electronic device (VED) includes a graphite substrate or framework in the shape of a hollow cylinder, and at least one continuous carbon nanotube (CNT) fiber in tension or compression around at least a portion of the graphite substrate. The at least one continuous CNT fiber can include a filament, yarn, braided yarn, film, fabric, or combination thereof. The at least one continuous CNT fiber is secured to the electrically conductive substrate by vacuum brazing or any other suitable means.

The application discloses a kind of multilayer composite ceramic coating with high-temperature stability and corrosion resistance on graphite surface and a preparation method thereof, ultra-high temperature ceramic oxide slurry is brushed on the surface of graphite substrate, first heat treatment is carried out, porous transition layer is obtained, then ultra-high temperature carbide slurry is brushed on the surface of porous transition layer, ultra-high temperature carbide layer is obtained after drying, then roughening treatment is carried out on the surface of ultra-high temperature carbide layer using ultra-high temperature carbide slurry, then second heat treatment is carried out, rough carbide layer is obtained, then dense projection is obtained by point pressure on the surface of rough carbide layer using metal carbide ceramic mixed slurry, and protective layer material is sprayed, and the method of the application can significantly improve the firmness of each layer, effectively avoid the reaction between graphite substrate and surface protective layer at high temperature, leading to coating failure and falling off, further enhance the use limit of protective layer, and have wide application prospect.

This invention discloses a graphite part, its preparation method, its application, and its evaluation method. The graphite part includes a graphite substrate and an amorphous carbon coating disposed on the surface of the graphite substrate. The graphite part satisfies Q=Y×Δρ×(Ra^0.5) / d≥4.0: By coupling the coating's energy dissipation capacity (Y), the substrate's gradient densification degree (Δρ), the substrate's surface morphology characteristics (Ra^0.5), and the coating's geometric constraints (d) to a single parameter Q, quantitative characterization and engineering controllability of the crack resistance performance of the amorphous carbon coating during high-temperature carbonization are achieved. In the graphite part prepared when Q≥4.0, the amorphous carbon coating does not crack or shed powder, which is beneficial for its application in ion implanters.

The present invention belongs to the technical field of ultra-high temperature ceramic materials and discloses a high-purity porous tantalum carbide ceramic, a preparation method thereof, and an application thereof. The present invention comprises the following steps: placing a porous graphite substrate horizontally in a vertical vapor deposition chamber, evacuating the chamber, introducing argon gas, increasing the reaction gas pressure to 10-100 mbar, and heating the graphite substrate to a deposition temperature of the tantalum element; delivering an inorganic tantalum salt and hydrogen into the chamber to deposit the tantalum element in a first region; introducing argon gas into the reaction chamber to increase the reaction gas pressure, increasing the carrier gas flow of the inorganic tantalum salt, and increasing the deposition temperature of the tantalum element to deposit the tantalum element in a second region, and repeating the process to deposit the tantalum element on the porous graphite substrate from the inside out; and after the tantalum element is deposited, heating the high-purity porous graphite substrate to react and obtain tantalum carbide. By adjusting the reaction conditions, the reaction gas flow gradually penetrates the porous material at different depths, and the tantalum is uniformly deposited at different positions.

The invention discloses a graphite negative electrode material and a preparation method thereof, a pole piece and an electrochemical device. The preparation method of the graphite negative electrode material comprises the following steps: performing heat treatment on a raw material mixture comprising graphite, an indium source and a solvent, thereby obtaining the graphite negative electrode material, wherein the mass ratio of the indium source to the graphite is 0.2%-2%; the indium source is an indium-containing compound; the temperature of the heat treatment is 200-1000 DEG C. The graphite negative electrode material comprises a graphite base material and a coating layer coating the surface of the graphite base material, and the coating layer comprises an indium element. When the graphite negative electrode material is actually applied to an electrochemical device such as a lithium battery, the lithium ion conductivity can be effectively improved, meanwhile, the stability of a formed SEI film is effectively improved, and finally, the comprehensive electrochemical performance such as the first coulombic efficiency, the cycle and storage stability and the like of the obtained lithium battery is integrally improved.

The invention discloses a preparation method and application of doped graphite, and belongs to the technical field of doped graphite. The method comprises the following steps: performing vacuum annealing on a single crystal metal substrate adsorbed with a doped element compound to obtain a doped element embedded single crystal metal substrate; the single crystal metal substrate embedded with the doping elements is attached to a graphite base material, heat preservation is conducted for 1-3 h at the temperature of 1000-1500 DEG C in a non-oxidizing atmosphere, then heat preservation is conducted for 4-12 h at the temperature of 700-900 DEG C, and the doped graphite is obtained after cooling. According to the invention, the doping elements are embedded into the single crystal metal substrate, and the graphite is doped through variable temperature growth, so that the super-lubricity is maintained while the doping uniformity and controllability are ensured, and the method is more suitable for being applied to electronic devices needing to maintain the super-lubricity.

The invention provides a method for repairing a wafer carrying disc, and the method comprises the following steps: providing a wafer carrying disc to be repaired, the wafer carrying disc to be repaired comprises a graphite substrate and a silicon carbide coating, the graphite substrate comprises a first surface and a second surface which are oppositely arranged, and the silicon carbide coating is located on the first surface; the to-be-repaired wafer loading disc is provided with a concave hole, and the concave hole penetrates through the silicon carbide coating and a part of the thickness of the graphite substrate; filling the concave hole with a repair material comprising a resin material, and graphitizing the resin material to obtain a graphitized repair structure; the maximum distance between the surface, away from the second surface, of the graphitization repair structure and the second surface is smaller than the distance between the surface, away from the graphite substrate, of the silicon carbide coating and the second surface; and forming a silicon carbide repairing structure in the concave hole, wherein the surface, away from the graphite substrate, of the silicon carbide repairing structure is flush with the surface, away from the graphite substrate, of the silicon carbide coating. Recycling and reusing of the wafer carrying disc can be achieved.

The invention provides a large-area (100) oriented metal organic framework ZIF-8 film as well as a preparation method and application thereof. Specifically, the method comprises the following steps: enabling at least part of the surface of a graphite substrate to be in contact with a ZIF-8 film synthesis solution containing Zn < 2 + > and 2-methylimidazole, enabling the Zn < 2 + > to react with the 2-methylimidazole, and forming the ZIF-8 alignment film on the graphite substrate. The ZIF-8 oriented film prepared by the method disclosed by the invention is uniform and compact, is highly oriented and has high H2 selective separation performance.

The invention belongs to the technical field of photoelectrocatalysis, and particularly discloses an integrated photo-anode and a preparation method and application thereof and a photoelectrode, the integrated photo-anode comprises a graphite substrate, the graphite substrate is made of high-purity graphite, and the surface roughness of the graphite substrate is within 3.5 microns; the active layer is arranged on the surface of one side of the graphite substrate, the component of the active layer is SiC, and the active layer is of a loose porous structure; and the interface resistance of the integrated photo-anode is 10-50 ohms. The integrated photo-anode has universality and good conductivity, and the photoelectrochemical water decomposition characteristic is excellent.

The invention belongs to the technical field of material preparation, and discloses a CVD (chemical vapor deposition) protection method for a special-shaped area of a graphite matrix, which comprises the following steps: S1, filling the special-shaped area of the graphite matrix with slurry which comprises expanded graphite powder, deionized water, polyethylene glycol and carbon nanotubes; s2, carrying out heat preservation for 5-15 minutes at the temperature of 200-300 DEG C in an inert atmosphere, and then carrying out heat preservation for 15-25 minutes at the temperature of 500-600 DEG C, so that the porosity of the slurry is kept at 40%-60%; s3, preparing a coating on the surface of the graphite substrate by using a CVD (chemical vapor deposition) process; and S4, removing the slurry and the coating of the graphite substrate in the special-shaped area. According to the method, the problem that a coating material is prone to non-uniform deposition in the CVD process of the special-shaped graphite piece is solved, the requirements for high-temperature stability, complex geometric adaptability, interface bonding reliability and process compatibility are met, and the problems that the coating precision is out of control, materials are wasted, and product performance is reduced are solved.

The invention relates to a device and a method for preparing polycrystalline silicon carbide, polycrystalline silicon carbide and application thereof. The apparatus comprises: a crucible; the graphite substrate is arranged on the crucible and is positioned at the upper part of the crucible; the air channel structure is arranged in the crucible and is used for introducing air into the crucible; the baffle is arranged in the crucible, a gap is formed between the baffle and the graphite substrate, a projection covers the graphite substrate, and a gap is formed between the baffle and the bottom wall of the crucible; and the heater is arranged in the crucible and is lower than the baffle. The device can be used for manufacturing polycrystalline silicon carbide with low resistivity.