Preparation method of graphite product and product thereof

Abstract

The invention discloses a preparation method of a graphite product, which is characterized by comprising the following steps: soaking a graphite block or a graphite flake to be treated in liquid resin for 2-5 hours under the pressure environment of 0.5-2 Mpa to obtain a graphite block or a graphite flake subjected to high-pressure impregnation and curing treatment; in an inert atmosphere, putting the graphite block or the graphite flake subjected to high-pressure dipping and curing treatment into a tube furnace for glass carbonization treatment, heating to 400 DEG C at the temperature of 30-400 DEG C at the heating rate of 0.5-10 DEG C per minute in the tube furnace, and then keeping for 2-3 hours after the holding temperature of 600-1200 DEG C is reached at the heating rate of 0.1-5 DEG C per minute; and naturally cooling after the program is finished. Cooling to room temperature, closing the equipment, and taking out a sample to obtain a graphite product with a vitrified carbon coating on the surface. The porosity of the graphite product is reduced, and the application stability of the graphite product in vacuum and other environments is facilitated. And the graphite with the vitrified carbon coating on the surface has better wear resistance and is difficult to fall off, so that the service life of the product is prolonged.

Description

Technical Field

[0001] The present invention relates to the field of new materials, and in particular to a preparation method of a graphite product and the product thereof. Background Art

[0002] Graphite is the crystalline form of elemental carbon and the most stable form of carbon under standard conditions. It consists of stacked graphene layers. In each layer, the carbon atoms are arranged in a honeycomb lattice with a bond length of 0.142 nm and an interplanar spacing of 0.335 nm. The bonds between the layers are relatively weak van der Waals bonds, which are usually occupied by gases. This allows the graphene-like layers to easily separate and slide past each other. As a result, the electrical conductivity perpendicular to the layers is reduced by a factor of about 1000. Synthetic and natural graphite are used on a large scale in pencils, lubricants and electrode production.

[0003] Graphite's high thermal stability and electrical and thermal conductivity make it widely used as an electrode and refractory material in high-temperature material processing applications. Graphite conducts electricity due to the significant electron delocalization within the carbon layers (a phenomenon known as aromaticity). These valence electrons are free to move, allowing them to conduct electricity and be used in applications such as arc lamp electrodes. The conductive properties of graphite powder make it useful as a pressure sensor in carbon microphones.

[0004] Carbon has three possible hybridization states—sp, sp2, and sp3—that enable it to form a variety of stable and metastable allotropes. Pure carbon allotropes exhibit a wide range of physical properties. Glassy carbon (GC), a disordered form of carbon primarily composed of sp2 bonds, is synthesized by the high-temperature pyrolysis of certain cross-linked polymers and has properties intermediate between those of graphite and ceramics. GC has a lower macroscopic density of approximately 1.5 g / cm3, compared to graphite (2.27 g / cm3) and diamond (3.5 g / cm3). Due to its non-graphitizing nature, its properties include chemical resistance and high-temperature stability. GC outperforms graphite in applications such as thermally stable crucibles and electrodes in electrochemical devices. Other applications include medical prosthetics due to its biocompatibility. Recently, this disordered form of carbon has attracted attention as an attractive precursor for the formation of novel high-pressure and high-temperature allotropes. Several different types of GC have been used in various high-pressure studies. Using different forms of glassy carbon may be important because factors such as microstructure and impurity levels are known from amorphous silicon to influence the formation of high-pressure allotropes.

[0005] Glassy carbon (GC) is a non-graphitizable carbon composed of graphite nanocrystals that are isotropically cross-linked between the crystals. This structure provides many important material properties, including high hardness, high-temperature resistance, impermeability, low electrical resistance, chemical resistance, and biocompatibility. These properties make it a useful material for applications in electrochemistry, corrosion, and medicine. GC is commonly used as a reference electrode in electrochemistry, as corrosion protection for current collectors, and as a surgical implant material for humans and animals. Its existence was first revealed in the 1930s and early 1940s, culminating in Rosalind E. Franklin's pioneering research in the 1940s. In the mid-1950s, materials scientist and diamond technology expert Bernard Redfern observed glassy carbon in the laboratories of the Silicon Carbide Company in Manchester, England. He noticed that the transparent tape he was using to secure ceramic samples (rocket nozzles) in a furnace retained certain structural properties after firing in an inert atmosphere. He searched for a polymer matrix that mirrored the structure of diamond and discovered a resol that had been specially prepared to solidify without a catalyst. Crucibles were produced from this phenolic resin and distributed to organisations such as UKAEA Harwell.

[0006] Glassy carbon is typically produced as a bulk material or film by carbonizing a resol-type thermosetting resin precursor. Common precursor resins are phenol formaldehyde and furfuryl alcohol. After coating and before heat treatment, the precursor is cured by temperature or a catalyst. Although most commercially produced glassy carbon materials are carbonized between 1000 and 2000°C, precursor carbonization is achieved by heat treatment in an inert atmosphere at a minimum temperature of 600°C. This production method is limited by the time and temperature required to carbonize the precursor. Polymer carbonization is a high-temperature heat treatment process that typically requires several hours, usually performed in an inert atmosphere, with additional time required to raise and lower the furnace temperature. For high-quality conversion from resin to carbon, a slow ramp rate of 1-5°C / min is used, resulting in typical conversion times of several hours. The high temperature and long carbonization time requirements are a bottleneck to the usability of glassy carbon in all its applications. Furthermore, if the material is to be used as a coating, the substrate itself must undergo the same heat treatment as the glassy carbon. Summary of the Invention

[0007] In order to overcome the above-mentioned defects of the prior art, an object of the present invention is to provide a graphite product.

[0008] By infiltrating glassy carbon into graphite, the friction resistance and sealing performance of graphite products in high-pressure applications are improved. This invention uses a rapid photon curing method or a thermal curing method to produce glassy carbon, converting resin into glassy carbon to produce a new graphite material, thereby overcoming the wear and airtightness issues of graphite products during use.

[0009] In order to achieve the purpose of the present invention, the technical solution adopted is:

[0010] A method for preparing a graphite product comprises the following steps:

[0011] Under a pressure of 0.5-2 MPa, the graphite block or graphite sheet to be treated is immersed in liquid resin for 2-5 hours to obtain a graphite block or graphite sheet after high-pressure impregnation curing treatment;

[0012] In an inert atmosphere, the graphite block or graphite sheet after high pressure impregnation curing is placed into a tube furnace for glass carbonization treatment.

[0013] In a tube furnace, heat the sample from 30-400°C at a rate of 0.5-10°C per minute to 400°C, then heat it at a rate of 0.1-5°C per minute to a holding temperature of 600-1200°C and hold for 2-3 hours.

[0014] After the program is completed, the temperature is naturally lowered to room temperature, the equipment is turned off, and the sample is taken out to obtain a graphite product with a glassy carbon coating on the surface.

[0015] In a preferred embodiment of the present invention, the weight ratio of the liquid resin to the graphite block or graphite sheet to be treated in the high-pressure impregnation treatment is 1-20:100.

[0016] In a preferred embodiment of the present invention, the liquid resin is any one or more of epoxy resin, furfural resin, phenolic resin, furan resin, polyester resin, vinyl ester, bismaleimide, thermosetting polyimide or cyanate ester, preferably epoxy resin or phenolic resin.

[0017] In a preferred embodiment of the present invention, the gas flow rate of the inert atmosphere is 0.5-3 liters / minute, and the inert atmosphere is nitrogen or argon.

[0018] A graphite product is prepared by the preparation method.

[0019] The beneficial effects of the present invention are:

[0020] The porosity of graphite products is reduced, which is beneficial to its stability in vacuum environments. Graphite with a glassy carbon coating on the surface has better wear resistance and is difficult to fall off, extending the service life of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of a graphite block with glassy carbon attached.

[0022] Figure 2 This is the SEM image of the processed glassy carbon.

[0023] Figure 3 This is the Raman spectrum of the processed glassy carbon.

[0024] Figure 4 This is the X-ray diffraction pattern of the processed glassy carbon. DETAILED DESCRIPTION

[0025] To make the objects, technical solutions, and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and examples. However, it should be understood that the specific embodiments described herein are merely intended to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, in the following structure, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion about the concepts of the present invention.

[0026] This invention combines the characteristics of graphite and glassy carbon to create a new product. By combining their high thermal stability, electrical conductivity, thermal conductivity, high hardness, high temperature resistance, and chemical resistance with the airtightness and durability of glassy carbon, this invention reduces graphite shedding during use, further improving product performance and broadening the application prospects of graphite products.

[0027] Example 1

[0028] The graphite block to be treated is immersed in epoxy resin and placed under a pressure of 0.5 MPa for 2 hours. The impregnated sample is placed in a tube furnace. In the tube furnace, the temperature is increased from 30°C to 400°C at a rate of 5°C / minute to 400°C. From 400°C to 800°C, the temperature is increased at a rate of 1°C / minute to a holding temperature of 800°C, where it is held for 2 hours. An inert atmosphere is maintained within the furnace at a constant nitrogen flow rate of 1 liter / minute. After the process is completed, the temperature is allowed to cool naturally. Once the temperature reaches room temperature, the equipment is turned off and the sample is removed for testing.

[0029] Its specific surface area has increased from 0.796m 2 / g dropped to 0.777m 2 / g, indicating that the porosity of the product is significantly reduced.

[0030] Example 2

[0031] The graphite blocks to be treated were immersed in phenolic resin and placed under a pressure of 2 MPa for 5 hours. The cured samples were then placed in a tube furnace. In the tube furnace, the temperature was increased from 30°C to 400°C at a rate of 0.5°C / min to 400°C. From 400°C to 1000°C, the temperature was increased at a rate of 0.1°C / min, reaching a holding temperature of 1000°C and held for 2 hours.

[0032] During the process, a constant nitrogen flow of 2 liters / minute was used to create an inert atmosphere in the furnace. After the process was completed, the temperature was naturally cooled to room temperature, the equipment was turned off, and the sample was taken out for testing. The specific surface area increased from 1.578 m2 before treatment to 1.578 m2.2 / g dropped to 0.820m 2 / g, indicating that the porosity of the product is significantly reduced.

[0033] The basic principles and main features of the invention and the advantages of the invention are shown and described above.

[0034] Those skilled in the art should understand that the present invention is not limited to the above-mentioned embodiments. The above-mentioned embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which shall fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for preparing a graphite product, characterized in that: The steps include: Under a pressure of 0.5-2 MPa, the graphite block or graphite sheet to be treated is immersed in liquid resin for 2-5 hours to obtain a graphite block or graphite sheet after high-pressure impregnation curing treatment; In an inert atmosphere, the graphite block or graphite sheet after high pressure impregnation curing is placed into a tube furnace for glass carbonization treatment. In a tube furnace, heat the sample from 30-400°C at a rate of 0.5-10°C per minute to 400°C, then heat it at a rate of 0.1-5°C per minute to a holding temperature of 600-1200°C and hold for 2-3 hours. After the program is completed, the temperature is naturally lowered to room temperature, the equipment is turned off, and the sample is taken out to obtain a graphite product with a glassy carbon coating on the surface.

2. The method for preparing a graphite product according to claim 1, wherein: The weight ratio of the liquid resin to the graphite block or graphite sheet to be treated in the high-pressure impregnation treatment is 1-20:

100.

3. The method for preparing a graphite product according to claim 1, wherein: The liquid resin is any one or more of epoxy resin, furfural resin, phenolic resin, furan resin, polyester resin, vinyl ester, bismaleimide, thermosetting polyimide or cyanate ester.

4. The method for preparing a graphite product according to claim 1, wherein: The gas flow rate of the inert atmosphere is 0.5-3 liters / minute, and the inert atmosphere is nitrogen or argon.

5. A graphite product, characterized in that: The graphite product is a product prepared by the preparation method according to any one of claims 1 to 4.

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