A method for preparing high-strength and high-purity graphite materials

Abstract

This invention relates to the field of graphite materials technology, and more specifically to a method for preparing high-strength, high-purity graphite materials. The method includes: dispersing diamond micron powder, carbon black, phenolic resin, and a surfactant in anhydrous ethanol in a predetermined proportion to form a slurry; drying and granulating the slurry; pre-pressing and dehydrating / curing the slurry; and finally sintering the slurry in a spark plasma sintering furnace to obtain high-strength, high-purity graphite materials. The graphite material prepared by this invention has a bulk density ≥ 2.0 g / cm³. 3 Vickers microhardness ≥1.78GPa, compressive strength ≥380MPa.

Description

Technical Field

[0001] This invention relates to the field of graphite materials technology, and more specifically, to a method for preparing high-strength, high-purity graphite materials. Background Technology

[0002] Graphite is an important industrial material with advantages such as high melting point, corrosion resistance, good electrical conductivity, and high thermal and electrical conductivity. It is widely used in many fields such as electronics, aerospace, energy, chemical industry, metallurgy, machinery, and petrochemicals. With the continuous advancement of science and technology, increasingly higher requirements are being placed on the strength, hardness, purity, and toughness of graphite. Therefore, the preparation of high-strength and high-purity graphite materials has received attention from both academia and industry.

[0003] Chinese Patent (CN112830784A) discloses a method for preparing glassy carbon materials using nanodiamonds as a precursor via spark plasma sintering. Chinese Patent (CN 110357074A) also discloses a method for preparing nano-onion carbon porous materials by in-situ transformation of nanodiamonds under high temperature and pressureless conditions, followed by high temperature and low pressure sintering.

[0004] Although advancements in manufacturing technology have significantly reduced the production cost of diamond, the price of nanodiamond powder remains relatively high. 50 Diamond micropowder with a diameter of about 50nm is currently priced at over 10,000 yuan / kg, far exceeding the price of most graphite materials on the market. This limits the widespread application of high-performance graphite prepared based on the diamond conversion method.

[0005] Researching and optimizing the preparation method of high-performance graphite based on diamond conversion can improve the performance of graphite materials while reducing production costs, which is of great significance for promoting technological progress in the high-performance graphite materials industry. Summary of the Invention

[0006] In view of this, and in view of the shortcomings of the prior art, the present invention provides a method for preparing high-strength and high-purity graphite materials, thereby achieving the goal of preparing high-performance graphite materials in a more economical and simple way.

[0007] To achieve the above objectives, the method for preparing high-strength, high-purity graphite materials provided by this invention includes:

[0008] Mixing and pulping: Weigh out diamond micro powder, carbon black, phenolic resin and surfactant in a predetermined ratio, disperse them in anhydrous ethanol to prepare a mixed slurry;

[0009] Drying and granulation: The mixed slurry is dried, crushed, and sieved to obtain granulated powder;

[0010] Pre-compression molding and dehydration curing are performed to solidify the granulated powder and obtain solid blocks.

[0011] Sintering: The solid block material is placed into a graphite mold and sintered in a spark plasma sintering furnace to obtain graphite material.

[0012] Optionally, the diamond micropowder has a D50 of less than 5 μm.

[0013] Optionally, the original particle size D50 of the activated carbon black micro powder is less than 50 nm, and the carbon black is preferably pyrolytic carbon black.

[0014] Optionally, the phenolic resin is an alcohol-soluble powdered phenolic resin.

[0015] Optionally, the surfactant is one of polyethyleneimine or tetramethylammonium hydroxide.

[0016] Optionally, the ratio of diamond micro powder: activated carbon black: phenolic resin: surfactant: anhydrous ethanol is 100:3-50:5-30:0.5-3:130.2-457.5.

[0017] Optionally, in the mixing and pulping step, the dispersion time is 1 to 10 hours.

[0018] Optionally, in the drying and granulation step, the drying temperature is 40–80°C.

[0019] Optionally, in the pre-compression molding and dehydration curing steps, the temperature is 140–200°C and the pressure is 10–50 MPa.

[0020] Optionally, in the sintering step, the pressure is 40-70 MPa, the sintering temperature is 1600-2000℃, the holding time is 5-60 minutes, and the heating rate is 50-300℃ / minute.

[0021] The beneficial effects of this invention are:

[0022] 1. Compared with the process of using pure diamond powder as a precursor, the present invention prepares high-strength graphite materials by introducing activated carbon black as a second carbon source. Without reducing the material performance, the production cost of the material is greatly reduced, which is conducive to promoting the industrial application of high-performance graphite materials.

[0023] 2. Compared with the process of preparing high-strength graphite materials using "diamond + carbon black", this invention improves the uniformity of dispersion by introducing phenolic resin as a binder and mixing it with anhydrous ethanol as a solvent liquid phase. Combined with post-processing steps such as drying, crushing, and granulation, this further enhances the uniformity of diamond and carbon black distribution, avoiding the reduction in material properties caused by uneven distribution of the first carbon source (diamond) and the second carbon source (carbon black). Furthermore, the binding and curing properties of phenolic resin ensure that the uniformly dispersed diamond and carbon black undergo minimal relative displacement during product preparation, minimizing the risk of reduced uniformity. Phenolic resin can also be pyrolyzed in situ at high temperatures to generate highly reactive carbon elements, improving the system's reactivity and enhancing the performance of the resulting product.

[0024] 3. Through preforming and warm-press dehydration and curing treatment, the amount of raw material filling can be increased, making full use of the graphite mold of SPS, which is especially suitable for preparing large-size graphite materials.

[0025] 4. Compared with existing methods for preparing high-performance graphite materials based on diamond conversion, this invention significantly reduces production costs, has a relatively simple process, high production efficiency, and does not cause a reduction in material performance. It has obvious comprehensive advantages in cost and performance, and is particularly suitable for industrial-scale preparation of high-performance graphite materials and products. Detailed Implementation

[0026] The following reference Figure 1 This invention describes a method for preparing a high-strength, high-purity graphite material according to an embodiment of the present invention. In this description, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature, that is, include one or more of that feature. In the description of the present invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified. When a feature "includes or contains" one or more of the features it encompasses, unless otherwise specifically described, this indicates that other features are not excluded and may be further included.

[0027] In the description of this embodiment, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0028] Figure 1 This is a process flow diagram of a high-strength, high-purity graphite material according to an embodiment of the present invention. Figure 1 As shown, this invention discloses a method for preparing a high-strength, high-purity graphite material, the preparation method comprising the following steps:

[0029] Step S10: Mixing and slurry preparation. Weigh diamond micro powder, carbon black, phenolic resin and surfactant in a preset ratio, disperse them in anhydrous ethanol to prepare a mixed slurry.

[0030] Step S20, drying and granulation: the mixed slurry is dried, crushed and sieved to obtain granulated powder;

[0031] Step S30, pre-compression molding and dehydration curing, the granulated powder is cured to obtain solid block material;

[0032] Step S40, sintering: The solid block material is placed into a graphite mold and sintered in a spark plasma sintering furnace to obtain graphite material.

[0033] In some embodiments of the present invention, the D50 of the diamond micropowder is less than 5 μm. In this embodiment, the D50 of the diamond micropowder is less than 5 μm, which provides a suitable specific surface area, resulting in a more uniform mixture.

[0034] In some embodiments of the present invention, the original particle size D50 of the activated carbon black micro powder is less than 50 nm, and the carbon black is preferably pyrolytic carbon black.

[0035] In this embodiment, the particle size of the activated carbon black powder is selected to give it a suitable specific surface area, resulting in a more uniform mixture.

[0036] In some embodiments of the present invention, the phenolic resin is an alcohol-soluble powdered phenolic resin. In this embodiment, the powdered phenolic resin is selected as a high-performance synthetic resin with excellent heat resistance, chemical corrosion resistance, and mechanical strength.

[0037] In some embodiments of the present invention, the surfactant is one of polyethyleneimine or tetramethylammonium hydroxide.

[0038] In some embodiments of the present invention, the ratio of diamond micro powder: activated carbon black: phenolic resin: surfactant: anhydrous ethanol is 100:3-50:5-30:0.5-3:130.2-457.5.

[0039] In this embodiment, diamond micro powder, activated carbon black, phenolic resin, surfactant and anhydrous ethanol are selected in appropriate proportions to prepare a graphite material with a high carbon content.

[0040] In some embodiments of the present invention, the dispersion time in the mixing and pulping step is 1 to 10 hours. In this embodiment, a dispersion time of 1 to 10 hours is selected, which has a better dispersion effect. It should be noted that the dispersion time can be any value from 1 to 10, such as 1.5 hours, 3 hours, 5 hours, 7 hours, etc.

[0041] In some embodiments of the present invention, the drying temperature in the drying and granulation step is 40–80°C. Specifically, it can be any value within the range of 40–80°C, such as 45°C, 50°C, 65°C, 70°C, etc.

[0042] In this embodiment, the drying temperature is 40-80°C to facilitate the evaporation of the liquid.

[0043] In some embodiments of the present invention, the temperature is 140–200°C and the pressure is 10–50 MPa in the pre-compression molding and dehydration curing steps.

[0044] In this embodiment, the pre-compression pressure is any value between 10 and 50 MPa. This pressure range ensures that the particles are compressed into clumps without causing excessively dense powder buildup, making processing and molding difficult. It also avoids machine damage and increased production costs caused by excessive pressure. The dehydration temperature is any value between 140 and 200°C, such as 145°C, 150°C, 165°C, 180°C, etc. This temperature setting allows for sufficient evaporation of moisture from the particles while avoiding energy waste caused by excessively high temperatures.

[0045] In some embodiments of the present invention, during the sintering step, the pressure is 40-70 MPa, the sintering temperature is 1600-2000°C, the holding time is 5-60 minutes, and the heating rate is 50-300°C / minute.

[0046] In this embodiment, the sintering temperature is 1600–2000℃, the holding time is 5–60 minutes, and the heating rate is 50–300℃ / minute to ensure a complete chemical reaction.

[0047] The present invention will be explained in detail below with several embodiments. The technical solutions in the embodiments of the present invention will be clearly and completely described. The described embodiments are only some embodiments of the present invention, and not all embodiments.

[0048] Example 1

[0049] A method for preparing a high-strength, high-purity graphite material includes the following steps:

[0050] 1) Raw material dispersion and slurry preparation

[0051] Weigh out 100 parts by weight of diamond micro powder, 3 parts by weight of activated carbon black, 5 parts by weight of phenolic resin and 0.5 parts by weight of polyethyleneimine, add 160 parts by weight of anhydrous ethanol, and ultrasonically disperse for 5 hours to ensure uniform mixing of all components and obtain a mixed slurry.

[0052] 2) Slurry drying and granulation

[0053] The mixed slurry obtained in step 1) is placed in a vacuum drying oven and dried at 50°C until the ethanol content of the solid phase is about 1.5%. Then it is ground and crushed in an agate mortar and granulated through a 60-mesh standard sieve.

[0054] 3) Pre-compression molding and dehydration curing

[0055] The granulated powder obtained in step 2) is loaded into an alloy mold and heated at 160℃ and 30MPa for 30 minutes to fully dehydrate and cure the phenolic resin, thus obtaining a solid block material.

[0056] 4) SPS sintering

[0057] The material processed in step 3) is placed into a graphite mold and then loaded into an SPS furnace. The vacuum is evacuated to below 0.1 Pa, a pressure of 40 MPa is applied, and the temperature is raised to 1800 °C at a rate of 100 °C / min. The temperature is held for 10 minutes to obtain a high-strength and high-purity graphite material.

[0058] The obtained graphite blocks were tested and found to have a carbon content of 99.995%, a bulk density of 1.58 g / cm3, a Vickers microhardness of 1.78 GPa, and a compressive strength of 380.78 MPa.

[0059] Example 2

[0060] A method for preparing a high-strength, high-purity graphite material includes the following steps:

[0061] 1) Raw material dispersion and slurry preparation

[0062] Weigh out 100 parts by weight of diamond micro powder, 30 parts by weight of activated carbon black, 5 parts by weight of phenolic resin and 0.8 parts by weight of polyethyleneimine, add 210 parts by weight of anhydrous ethanol, and ultrasonically disperse for 6 hours to ensure uniform mixing of all components and obtain a mixed slurry.

[0063] 2) Slurry drying and granulation

[0064] The mixed slurry obtained in step 1) is placed in a vacuum drying oven and dried at 50°C until the ethanol content of the solid phase is about 1.5%. Then it is ground and crushed in an agate mortar and granulated through a 60-mesh standard sieve.

[0065] 3) Pre-compression molding and dehydration curing

[0066] The granulated powder obtained in step 2) is loaded into an alloy mold and heated at 160℃ and 30MPa for 30 minutes to fully dehydrate and cure the phenolic resin, thus obtaining a solid block material.

[0067] 4) SPS sintering

[0068] The material processed in step 3) is placed into a graphite mold and then loaded into an SPS furnace. The vacuum is evacuated to below 0.1 Pa, a pressure of 40 MPa is applied, and the temperature is raised to 1800 °C at a rate of 100 °C / min. The temperature is held for 10 minutes to obtain a high-strength and high-purity graphite material.

[0069] The obtained graphite blocks were tested and found to have a carbon content of 99.997%, a bulk density of 1.61 g / cm3, a Vickers microhardness of 1.85 GPa, and a compressive strength of 410.22 MPa.

[0070] Example 3

[0071] A method for preparing a high-strength, high-purity graphite material includes the following steps:

[0072] 1) Raw material dispersion and slurry preparation

[0073] Weigh out 100 parts by weight of diamond micro powder, 30 parts by weight of activated carbon black, 20 parts by weight of phenolic resin and 1.0 part by weight of polyethyleneimine, add 280 parts by weight of anhydrous ethanol, and ultrasonically disperse for 6 hours to make the components uniformly mixed to obtain a mixed slurry.

[0074] 2) Slurry drying and granulation

[0075] The mixed slurry obtained in step 1) is placed in a vacuum drying oven and dried at 50°C until the ethanol content of the solid phase is about 1.5%. Then it is ground and crushed in an agate mortar and granulated through a 60-mesh standard sieve.

[0076] 3) Pre-compression molding and dehydration curing

[0077] The granulated powder obtained in step 2) is loaded into an alloy mold and heated at 160℃ and 30MPa for 30 minutes to fully dehydrate and cure the phenolic resin, thus obtaining a solid block material.

[0078] 4) SPS sintering

[0079] The material processed in step 3) is placed into a graphite mold and then loaded into an SPS furnace. The vacuum is evacuated to below 0.1 Pa, a pressure of 40 MPa is applied, and the temperature is raised to 1800 °C at a rate of 100 °C / min. The temperature is held for 10 minutes to obtain a high-strength and high-purity graphite material.

[0080] The obtained graphite blocks were tested and found to have a carbon content of 99.995%, a bulk density of 1.62 g / cm3, a Vickers microhardness of 1.91 GPa, and a compressive strength of 430.56 MPa.

[0081] Example 4

[0082] A method for preparing a high-strength, high-purity graphite material includes the following steps:

[0083] 1) Raw material dispersion and slurry preparation

[0084] Weigh out 100 parts by weight of diamond micro powder, 3 parts by weight of activated carbon black, 20 parts by weight of phenolic resin and 0.5 parts by weight of polyethyleneimine, add 200 parts by weight of anhydrous ethanol, and ultrasonically disperse for 6 hours to ensure uniform mixing of all components and obtain a mixed slurry.

[0085] 2) Slurry drying and granulation

[0086] The mixed slurry obtained in step 1) is placed in a vacuum drying oven and dried at 50°C until the ethanol content of the solid phase is about 1.5%. Then it is ground and crushed in an agate mortar and granulated through a 60-mesh standard sieve.

[0087] 3) Pre-compression molding and dehydration curing

[0088] The granulated powder obtained in step 2) is loaded into an alloy mold and heated at 160℃ and 30MPa for 30 minutes to fully dehydrate and cure the phenolic resin, thus obtaining a solid block material.

[0089] 4) SPS sintering

[0090] The material processed in step 3) is placed into a graphite mold and then loaded into an SPS furnace. The vacuum is evacuated to below 0.1 Pa, a pressure of 40 MPa is applied, and the temperature is raised to 1800 °C at a rate of 100 °C / min. The temperature is held for 10 minutes to obtain a high-strength and high-purity graphite material.

[0091] The obtained graphite blocks were tested and found to have a carbon content of 99.996%, a bulk density of 1.62 g / cm3, a Vickers microhardness of 1.98 GPa, and a compressive strength of 480.66 MPa.

[0092] Example 5

[0093] A method for preparing a high-strength, high-purity graphite material includes the following steps:

[0094] 1) Raw material dispersion and slurry preparation

[0095] Weigh out 100 parts by weight of diamond micro powder, 30 parts by weight of activated carbon black, 20 parts by weight of phenolic resin and 1.0 part by weight of polyethyleneimine, add 280 parts by weight of anhydrous ethanol, and ultrasonically disperse for 6 hours to make the components uniformly mixed to obtain a mixed slurry.

[0096] 2) Slurry drying and granulation

[0097] The mixed slurry obtained in step 1) is placed in a vacuum drying oven and dried at 50°C until the ethanol content of the solid phase is about 1.5%. Then it is ground and crushed in an agate mortar and granulated through a 60-mesh standard sieve.

[0098] 3) Pre-compression molding and dehydration curing

[0099] The granulated powder obtained in step 2) is loaded into an alloy mold and heated at 160℃ and 50MPa for 30 minutes to fully dehydrate and cure the phenolic resin, thus obtaining a solid block material.

[0100] 4) SPS sintering

[0101] The material processed in step 3) is placed into a graphite mold and then loaded into an SPS furnace. The vacuum is evacuated to below 0.1 Pa, a pressure of 70 MPa is applied, and the temperature is raised to 1800 °C at a rate of 100 °C / min. The temperature is held for 10 minutes to obtain a high-strength and high-purity graphite material.

[0102] The obtained graphite blocks were tested and found to have a carbon content of 99.998%, a bulk density of 1.64 g / cm3, a Vickers microhardness of 1.98 GPa, and a compressive strength of 540.33 MPa.

[0103] Example 6

[0104] A method for preparing a high-strength, high-purity graphite material includes the following steps:

[0105] 1) Raw material dispersion and slurry preparation

[0106] Weigh out 100 parts by weight of diamond micro powder, 30 parts by weight of activated carbon black, 20 parts by weight of phenolic resin and 1.0 part by weight of polyethyleneimine, add 280 parts by weight of anhydrous ethanol, and ultrasonically disperse for 6 hours to make the components uniformly mixed to obtain a mixed slurry.

[0107] 2) Slurry drying and granulation

[0108] The mixed slurry obtained in step 1) is placed in a vacuum drying oven and dried at 50°C until the ethanol content of the solid phase is about 1.5%. Then it is ground and crushed in an agate mortar and granulated through a 60-mesh standard sieve.

[0109] 3) Pre-compression molding and dehydration curing

[0110] The granulated powder obtained in step 2) is loaded into an alloy mold and heated at 200℃ and 50MPa for 30 minutes to fully dehydrate and cure the phenolic resin, thus obtaining a solid block material.

[0111] 4) SPS sintering

[0112] The material processed in step 3) is placed into a graphite mold and then loaded into an SPS furnace. The vacuum is evacuated to below 0.1 Pa, a pressure of 70 MPa is applied, and the temperature is raised to 2000 °C at a rate of 100 °C / min. The temperature is held for 10 minutes to obtain a high-strength and high-purity graphite material.

[0113] The obtained graphite blocks were tested and found to have a carbon content of 99.997%, a bulk density of 1.71 g / cm3, a Vickers microhardness of 2.25 GPa, and a compressive strength of 620.12 MPa.

[0114] Comparative Example 1:

[0115] A method for preparing a high-strength, high-purity graphite material includes the following steps:

[0116] 1) Raw material dispersion and slurry preparation

[0117] Weigh out 100 parts of diamond micro powder and 3 parts of activated carbon black by weight, and grind them in an agate mortar to make the components evenly mixed.

[0118] 2) SPS sintering

[0119] The material processed in step 1) is placed into a graphite mold and then loaded into an SPS furnace. The vacuum is evacuated to below 0.1 Pa, a pressure of 40 MPa is applied, and the temperature is raised to 1800 °C at a rate of 100 °C / min. The temperature is held for 10 minutes to obtain a high-strength and high-purity graphite material.

[0120] The obtained graphite blocks were tested and found to have a carbon content of 99.995%, a bulk density of 1.57 g / cm3, a Vickers microhardness of 1.65 GPa, and a compressive strength of 270.66 MPa.

[0121] Comparative Example 2:

[0122] 1) Raw material dispersion and slurry preparation

[0123] Weigh out 100 parts by weight of diamond micro powder, 3 parts by weight of activated carbon black, and 5 parts by weight of phenolic resin. Grind them in an agate mortar to make the components evenly mixed.

[0124] 2) SPS sintering

[0125] The material processed in step 1) is placed into a graphite mold and then loaded into an SPS furnace. The vacuum is evacuated to below 0.1 Pa, a pressure of 40 MPa is applied, and the temperature is raised to 1800 °C at a rate of 100 °C / min. The temperature is held for 10 minutes to obtain a high-strength and high-purity graphite material.

[0126] The obtained graphite blocks were tested and found to have a carbon content of 99.997%, a bulk density of 1.57 g / cm3, a Vickers microhardness of 1.68 GPa, and a compressive strength of 285.20 MPa.

[0127] Comparative Example 3:

[0128] A method for preparing a high-strength, high-purity graphite material includes the following steps:

[0129] 1) Raw material dispersion and slurry preparation

[0130] Weigh out 100 parts by weight of diamond micro powder, 3 parts by weight of activated carbon black, and 5 parts by weight of phenolic resin. Grind them in an agate mortar to make the components evenly mixed.

[0131] 2) Pre-compression molding and dehydration curing

[0132] The granulated powder obtained in step 1) is loaded into an alloy mold and heated at 160℃ and 30MPa for 30 minutes to fully dehydrate and cure the phenolic resin, thus obtaining a solid block material.

[0133] 3) SPS sintering

[0134] The material processed in step 2) is placed into a graphite mold and then loaded into an SPS furnace. The vacuum is evacuated to below 0.1 Pa, a pressure of 40 MPa is applied, and the temperature is raised to 1800 °C at a rate of 100 °C / min. The temperature is held for 10 minutes to obtain a high-strength and high-purity graphite material.

[0135] The obtained graphite blocks were tested and found to have a carbon content of 99.996%, a bulk density of 1.58 g / cm3, a Vickers microhardness of 1.75 GPa, and a compressive strength of 330.80 MPa.

[0136] Comparative Example 4

[0137] A method for preparing a high-strength, high-purity graphite material includes the following steps:

[0138] 1) Raw material dispersion and slurry preparation

[0139] Weigh out 100 parts by weight of diamond micro powder, 3 parts by weight of activated carbon black, 5 parts by weight of phenolic resin and 0.5 parts by weight of polyethyleneimine, add 160 parts by weight of anhydrous ethanol, and ultrasonically disperse for 5 hours to ensure uniform mixing of all components and obtain a mixed slurry.

[0140] 2) Slurry drying and crushing

[0141] The mixed slurry obtained in step 1) is placed in a vacuum drying oven and dried at 50°C until the ethanol content of the solid phase is about 1.5%. It is then simply crushed until it can be loaded into the alloy mold, without grinding or granulation.

[0142] 3) Pre-compression molding and dehydration curing

[0143] The granulated powder obtained in step 2) is loaded into an alloy mold and heated at 160℃ and 30MPa for 30 minutes to fully dehydrate and cure the phenolic resin, thus obtaining a solid block material.

[0144] 4) SPS sintering

[0145] The material processed in step 3) is placed into a graphite mold and then loaded into an SPS furnace. The vacuum is evacuated to below 0.1 Pa, a pressure of 40 MPa is applied, and the temperature is raised to 1800 °C at a rate of 100 °C / min. The temperature is held for 10 minutes to obtain a high-strength and high-purity graphite material.

[0146] The obtained graphite blocks were tested and found to have a carbon content of 99.997%, a bulk density of 1.68 g / cm3, a Vickers microhardness of 1.76 GPa, and a compressive strength of 338.50 MPa.

[0147] The graphite materials prepared according to Examples 1-6 and Comparative Examples 1 and 2 were experimentally analyzed. The analysis dimensions included the carbon content, bulk density, Vickers microhardness, and compressive strength of the graphite materials. The analysis results are shown in Table 1.

[0148] Table 1 Performance test results of graphite materials

[0149]

[0150] Results analysis:

[0151] 1. As can be seen from Examples 1-6, overall, with the increase of phenolic resin content, the bulk density, microhardness and compressive strength of the obtained graphite blocks all increase; with the increase of curing temperature and pressure, the bulk density, microhardness and compressive strength of the obtained graphite blocks all increase; with the increase of SPS sintering temperature and pressure, the bulk density, microhardness and compressive strength of the obtained graphite blocks all increase.

[0152] 2. By comparing Comparative Example 1 and Example 1, it can be seen that, under the same process conditions, without adding phenolic resin and without using liquid phase mixing, granulation and curing processes, the bulk density, microhardness and compressive strength of the obtained graphite blocks are significantly reduced.

[0153] 3. By comparing Comparative Example 2, Comparative Example 1 and Example 1, it can be seen that, under the same process conditions, although phenolic resin was added, the mixing uniformity of the raw materials was worse because the liquid phase mixing, granulation and curing process was not adopted, resulting in poor uniformity of the graphite block material. Consequently, the bulk density, microhardness and compressive strength of the material were reduced.

[0154] 4. By comparing Comparative Examples 3, 2, and 1 with Example 1, it can be seen that, under the same conditions, although phenolic resin was added and a curing process was adopted, the uniformity of the raw material mixing was worse because liquid phase mixing and granulation processes were not used. This resulted in poor uniformity of the graphite block material, and consequently, the bulk density, microhardness, and compressive strength of the material were all reduced.

[0155] 5. By comparing Comparative Examples 4, 3, 2, and 1 with Example 1, it can be seen that, under the same conditions, although phenolic resin was added and liquid-phase mixing and curing processes were adopted, the uniformity of the raw material mixing was still poor due to the lack of granulation process, resulting in insufficient uniformity of the graphite block material. Consequently, the bulk density, microhardness, and compressive strength of the material were still relatively low.

[0156] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solutions of the present invention, as long as they do not depart from the spirit and scope of the technical solutions of the present invention, should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing a high-strength, high-purity graphite material, characterized in that, The preparation method includes: mixing and slurry preparation, weighing diamond micro powder, carbon black, phenolic resin and surfactant in a preset ratio, dispersing them in anhydrous ethanol to obtain a mixed slurry; Drying and granulation: The mixed slurry is dried, crushed, and sieved to obtain granulated powder; Pre-compression molding and dehydration curing are performed, followed by further curing of the granulated powder to obtain solid block material; Sintering: The solid block material is placed in a graphite mold and sintered in a spark plasma sintering furnace to obtain graphite material. The ratio of diamond micro powder to carbon black to phenolic resin to surfactant to anhydrous ethanol is 100:(3~50):(5~30):(0.5~3):(130.2~457.5) by mass. In the pre-compression molding and dehydration curing steps, the temperature is 140~200℃ and the pressure is 10~50MPa.

2. The method for preparing high-strength, high-purity graphite material according to claim 1, characterized in that, The diamond micro powder D 50 Less than 5μm.

3. The method for preparing high-strength, high-purity graphite material according to claim 1, characterized in that, The primary particle size D of the carbon black 50 The carbon black is less than 50 nm and is pyrolytic carbon black.

4. The method for preparing high-strength, high-purity graphite material according to claim 1, characterized in that, The phenolic resin is an alcohol-soluble powdered phenolic resin.

5. The method for preparing high-strength, high-purity graphite material according to claim 1, characterized in that, The surfactant is either polyethyleneimine or tetramethylammonium hydroxide.

6. The method for preparing high-strength, high-purity graphite material according to any one of claims 1-5, characterized in that, In the mixing and pulping step, the dispersion time is 1 to 10 hours.

7. The method for preparing high-strength, high-purity graphite material according to claim 1, characterized in that, In the drying and granulation step, the drying temperature is 40~80℃.

8. The method for preparing high-strength, high-purity graphite material according to any one of claims 1-5, characterized in that, In the sintering step, the pressure is 40~70MPa, the sintering temperature is 1600~2000℃, the holding time is 5~60 minutes, and the heating rate is 50~300℃ / minute.

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