CN112723887A - Preparation method of high-density ultrafine particle graphite for ionization chamber - Google Patents
Preparation method of high-density ultrafine particle graphite for ionization chamber Download PDFInfo
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Abstract
The invention provides a preparation method of high-density ultrafine particle graphite for an ionization chamber, which comprises the following steps: crushing coal tar pitch, stirring with first organic solvent at 50-100 deg.C, extracting insoluble substance, crushing, and stirring with second organic solvent at 50-100 deg.C to obtain soluble substance solution; adding the soluble substance solution as a binder into a kneader to perform liquid phase mixing when the temperature of the ultrafine-particle-size aggregate carbon in the kneader reaches a preset temperature, heating to a constant temperature above the boiling point of the second organic solvent, and evaporating the solvent to obtain a paste; crushing the paste to obtain pressed powder; filling the pressed powder into a die for compression molding, maintaining pressure and relieving pressure to obtain a green body sample; carbonizing the green body sample in an inert atmosphere, heating to a first preset carbonization final temperature, and keeping to obtain a carbonized product; and (3) carrying out impregnation densification treatment and pressure maintaining on the carbonized product, carrying out secondary carbonization after impregnation is finished, keeping at a second preset carbonization final temperature, carrying out graphitization treatment and maintenance, cooling and discharging from the furnace.
Description
Technical Field
The invention relates to a preparation technology of high-density ultrafine-grained graphite for an ionization chamber, in particular to a preparation method of high-density ultrafine-grained graphite for the ionization chamber by adopting a liquid-phase mixing process.
Background
High-density carbon/graphite material (density is more than or equal to 1.82 g/cm)3And the particle size of the aggregate is less than or equal to 20 mu m), has the characteristics of low porosity, high specific strength, excellent heat conductivity, high purity, good thermal shock resistance, self-lubricating inertia, good thermal stability in corrosive atmosphere, strong stability to acid-base chemical corrosion and the like, and is widely applied to the civil and aerospace aviation and nuclear industry fields of air ionization chambers, reactor moderators/reflectors, reactor gamma irradiation resistant interaxial sealing materials, electric spark processing, metal continuous casting, pulling of monocrystalline silicon crucibles, evaporators, missile/rocket nozzles, aerospace plane interaxial sealing materials and the like.
The rapid development of science and technology requires materials with the characteristics of high densification, multiple functionalization and the like so as to meet the working requirements of the materials under complex and harsh environmental conditions. Fine graphite particles have incomparable advantages such as high mechanical strength, low porosity and pore size distribution, and excellent surface fine processing characteristics, because the raw material particles are fine and have a compact and uniform structure.
Song King Bright et al (Preparation of binding nanopore-isotropic graph for inhibiting the liquid fluoride salt and Xe)135(iii) duration for molten salt nuclear reactor, carbon 79(2014) 36-45); liu Lang, Song Yong loyalty et al (a preparation method of a mould pressing binderless high-strength high-density material, No. CN101265102A) uses mesophase carbon microspheres as raw materials to prepare carbon/graphite materials by a binderless self-sintering process, and the preparation process is simple and the production is carried outThe period is short. Liu Zhan et al (a preparation method of graphite material, an authorization notice number: CN 101648808B) adopts asphalt coke with a particle size of less than 20 μm as aggregate carbon, and the graphite developed by the secondary coke process has better thermal physical properties. However, the volume shrinkage of the product in the heat treatment stage of the two processes is too large, so that the sample is easy to crack, and the industrialization of material preparation cannot be realized in a short time. The density and the grain size of the graphite material are critical to the strength of the material, the micronization and the density increase of the graphite grains are simultaneously realized, and the excellent performance of the produced graphite cannot be compared with that of high-density and high-strength graphite. However, for the conventional graphite preparation process, the smaller the particle size of the aggregate carbon is, the larger the specific surface area and the surface energy of the particles are, the more easily the particles are agglomerated with each other to form defects, and finally the performance of the graphite product is reduced and even the graphite product is cracked; in addition, the amount of binder pitch required to achieve a uniform coating structure is also increasing. The asphalt is composed of hydrocarbon and a large amount of polycyclic aromatic hydrocarbon, the group composition of the asphalt is divided into gamma components according to the chemical similarity and compatibility rule, namely, the toluene soluble substance mainly plays the role of a solvent to adjust the fluidity of the asphalt and improve the wettability of the asphalt to aggregate; the beta component, namely the quinoline soluble matter insoluble in toluene is the main component playing a role in bonding in the asphalt; the alpha component, quinoline insoluble, is the primary carrier for carbon residue formation. During the heat treatment, mainly the beta and gamma components are thermally decomposed to generate low-component gas. Therefore, the increase of the content of the binder pitch causes the increase of the low component emission, and the difficulty of the heat treatment process of the product is increased, which is particularly obvious for large-size products.
The Xigeli group is taken as a top-grade carbon research and development and production enterprise in the world, aiming at providing the highest-end graphite, the size enlargement of the ultrafine particle graphite cannot be realized until now, the RINGSDORFF-R8710/8650 ultrafine particle graphite is applied to an air ionization chamber and precise discharge machining, the standard blank size of the product only reaches 610mm multiplied by 390mm multiplied by 190mm/1230mm multiplied by 480mm multiplied by 260mm, the graphite with the standard size is difficult to be acquired in China, and the price is expensive. ZXF-5Q of POCO in the United states and HPG-510 of carbon in east ocean in Japan can realize high density and high strength, but products with the thickness of more than 150mm in three directions are difficult to obtain in China.
In conclusion, the traditional graphite production process route cannot meet the preparation process requirements of the ultrafine particle graphite, and the preparation and wide application of the material are severely restricted. At present, the performance of common carbon/graphite materials cannot meet the use requirements of special fields, and particularly, the development of a preparation scheme of a high-density carbon/graphite material with ultrafine particles, which is easy to amplify, is urgently needed for the graphite material for nuclear reactors, aerospace and large-scale air ionization chambers.
Disclosure of Invention
The invention aims to provide a preparation method of high-density ultrafine particle graphite for an ionization chamber, which has a compact microstructure, a fine grain size and excellent thermophysical properties.
Based on the chemical similarity and intermiscibility rule, the invention adopts an organic solvent to carry out component cutting on the binder asphalt, selects the asphalt effective binding beta component as the binder to be uniformly coated on the aggregate carbon with the superfine particle size in a liquid phase dispersion and mixing mode, on one hand, the mutual agglomeration among superfine particles is avoided, the interface combination of the binder and the aggregate carbon is improved, on the other hand, the effective binding beta component is cut out as the binder to reduce the discharge amount of low components on the premise of ensuring the strength of the product, thereby reducing the heat treatment difficulty of the product; and (3) performing isostatic pressing, carbonization, impregnation and high-temperature graphitization on the paste pressing powder to prepare the high-density fine-grain-size carbon/graphite material.
The invention provides a preparation method of high-density ultrafine particle graphite for an ionization chamber, which comprises the following steps:
step S1, crushing coal tar pitch, stirring the crushed coal tar pitch and a first organic solvent at the temperature of 50-100 ℃, extracting to obtain insoluble substances, drying the solvent, crushing the insoluble substances again, and fully stirring the dried insoluble substances and a second organic solvent at the temperature of 50-100 ℃ to obtain a soluble substance solution;
step S2, when the temperature of the ultrafine-particle-size aggregate carbon in the kneading machine reaches a preset temperature, adding a soluble substance solution of a second organic solvent as a binder into the kneading machine for liquid-phase mixing for a first preset time, then heating to a temperature above the boiling point of the second organic solvent, keeping the temperature for a second preset time, and evaporating the solvent to obtain a paste;
step S3, crushing the paste to obtain pressed powder;
step S4, filling the pressed powder into a die, pressing and forming under the first pressure condition, keeping the pressure for a third preset time, and relieving the pressure to obtain a green body sample;
step S5, carbonizing the green body sample in an inert atmosphere, heating at a first preset heating rate to reach a first preset carbonization final temperature, and keeping the first preset constant temperature time to obtain a carbonized product;
and step S6, carrying out impregnation densification treatment on the carbonized product at a preset pressure value, maintaining the pressure for a fourth preset time, carrying out secondary carbonization at a second preset temperature rise rate after the impregnation is finished, reaching a second preset carbonization final temperature, keeping the second preset constant temperature time, carrying out graphitization treatment, keeping the third preset constant temperature time, cooling and discharging.
In step S1, the coal tar pitch is crushed into 20-50 μm fragments, the fragments and the first organic solvent are stirred for 30-120min at 50-100 ℃, insoluble substances are obtained by adopting a Buchner funnel negative pressure suction filtration method, the insoluble substances are crushed again after the solvent is dried to 20-50 μm fragments, and the fragments and the second organic solvent are fully stirred for 30-120min at 50-100 ℃.
Wherein the first organic solvent is a mixed solution of one or more of the following solvents: toluene, benzene, n-hexane, acetone; and/or the second organic solvent is a mixed solution of one or more of the following solvents: quinoline, pyridine, azomethyl pyrrolidone and tetrahydrofuran.
In the step S2, when the temperature of the ultrafine particle size aggregate carbon in the kneader reaches 50 to 120 ℃, adding a soluble substance solution of a second organic solvent as a binder into the kneader to perform liquid phase mixing for 1 to 3 hours, then heating to a temperature higher than the boiling point of the second organic solvent, maintaining the temperature for 1 to 3 hours, and evaporating the solvent to obtain the paste.
Wherein the aggregate carbon is asphalt coke, petroleum coke or needle coke.
Wherein the second organic solvent soluble substance accounts for 22-35% of the total mass of the mixed raw materials consisting of the second organic solvent soluble substance and the aggregate carbon.
Wherein, in the step S3, the paste is crushed to a size of 5-50 μm.
In the step S4, the pressed powder is put into a die, pressed into a mold under the pressure of 120-200MPa, kept for 10-30min, and decompressed to obtain a green body sample.
In the step S5, the green body sample is carbonized in argon gas, the temperature is raised at a rate of 2-6 ℃/min to reach a final carbonization temperature of 1000 and 1050 ℃, and the temperature is maintained for 20-60min to obtain a carbonized product.
In the step S6, the carbonized product is subjected to impregnation densification treatment under 2-4MPa, pressure is maintained for 1-3h, secondary carbonization is performed at a preset temperature rise rate of 5-10 ℃/min after impregnation is finished, the final temperature of the second preset carbonization is 1000-1050 ℃, the temperature is maintained for 20-60min, graphitization treatment is performed, the temperature is maintained for 0.5-1h, and the carbonized product is cooled and taken out of the furnace.
The invention has the following advantages:
the ultrafine grain size aggregate carbon (1-20 mu m) is used as the raw material, so that the defects and pores in the raw material particles are reduced, and the grain refinement of the graphite material is realized. According to the chemical similarity and compatibility rule, the coal pitch is subjected to multi-section component cutting by adopting an organic solvent, components which have small asphalt molecular weight and are difficult to coke and form carbon are removed, the discharge amount of low components in the heat treatment stage is reduced, and the roasting difficulty is reduced; avoiding the influence of the large molecular weight of the asphalt and the carbon black component on the uniformly mixed coating structure. The asphalt effective bonding beta component, namely the second organic solvent is used as the bonding agent to be uniformly coated on the ultrafine-grain-size aggregate carbon in a liquid-phase dispersion mixing mode, so that on the premise of ensuring the product performance, mutual agglomeration among ultrafine grains is avoided, and on the other hand, the interface bonding of the bonding agent and the aggregate carbon is improved. Adopts a fine cutting mode to the asphalt, enlarges the proportion of effective components and ensures that the density is more than or equal to 1.82g/cm3The preparation difficulty of the graphite material with the ultrafine grain diameter is greatly reduced, and the industrial popularization is facilitated.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure.
Drawings
Other features, objects, and advantages of the present disclosure will become more apparent from the following detailed description of non-limiting embodiments when taken in conjunction with the accompanying drawings. In the drawings:
fig. 1 is a schematic flow chart of a method for preparing highly dense ultrafine graphite particles for an ionization chamber according to an embodiment of the present invention.
Detailed Description
Hereinafter, exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily implement them. Also, for the sake of clarity, parts not relevant to the description of the exemplary embodiments are omitted in the drawings.
In the present disclosure, it is to be understood that terms such as "including" or "having," etc., are intended to indicate the presence of the disclosed features, numbers, steps, behaviors, components, parts, or combinations thereof, and are not intended to preclude the possibility that one or more other features, numbers, steps, behaviors, components, parts, or combinations thereof may be present or added.
It should be further noted that the embodiments and features of the embodiments in the present disclosure may be combined with each other without conflict. The present disclosure will be described in detail below with reference to the accompanying drawings in conjunction with embodiments.
Fig. 1 is a schematic flow chart of a method for preparing highly dense ultrafine graphite particles for an ionization chamber according to an embodiment of the present invention, and as shown in fig. 1, the method for preparing highly dense ultrafine graphite particles for an ionization chamber according to the present invention includes the following steps:
step S1, crushing coal tar pitch, stirring the crushed coal tar pitch and a first organic solvent at the temperature of 50-100 ℃, extracting to obtain insoluble substances, drying the solvent, crushing the insoluble substances again, and fully stirring the dried insoluble substances and a second organic solvent at the temperature of 50-100 ℃ to obtain a soluble substance solution;
wherein the softening point of the coal pitch is 70-270 ℃.
In one embodiment of the invention, the bitumen and insolubles may be broken into pieces of size 20-50 μm.
In one embodiment of the present invention, the crushed asphalt and the first organic solvent or the second organic solvent may be stirred at a temperature of 50 to 100 ℃ for 30 to 120 min.
In one embodiment of the present invention, the first organic solvent may be a mixed solution of one or more of the following solvents: toluene, benzene, n-hexane and acetone, wherein the second organic solvent can be a mixed solution of one or more of the following solvents: quinoline, pyridine, azomethyl pyrrolidone and tetrahydrofuran.
In one embodiment of the present invention, the insoluble materials in the first organic solvent and the second organic solvent can be extracted by a buchner funnel negative pressure filtration method.
And step S2, when the temperature of the ultrafine-particle-size aggregate carbon in the kneading machine reaches a preset temperature, adding a soluble substance solution of a second organic solvent as a binder into the kneading machine for liquid-phase mixing for a first preset time, then heating to a temperature above the boiling point of the second organic solvent, keeping the temperature for a second preset time, and evaporating the solvent to obtain the paste.
The preset temperature is 50-120 ℃, the first preset time is 1-3h, and the second preset time is 1-3 h.
In one embodiment of the invention, the aggregate carbon can be pitch coke, petroleum coke, needle coke and the like, the average particle size of the aggregate carbon is 1-20 μm, the residual carbon is 55-85%, the volatile matter is 20-60%, and the ash content is less than or equal to 0.1%.
In one embodiment of the invention, the second organic solvent soluble substance accounts for 22-35% of the total mass of the mixed raw materials consisting of the second organic solvent soluble substance and the aggregate carbon.
Step S3, crushing the paste to obtain pressed powder;
in one embodiment of the invention, the paste may be crushed to a size of 5-50 μm.
Step S4, filling the pressed powder into a die, pressing and forming under the first pressure condition, keeping the pressure for a third preset time, and relieving the pressure to obtain a green body sample;
wherein the first pressure may be 120-.
Step S5, carbonizing the green body sample in an inert atmosphere, heating at a first preset heating rate to reach a first preset carbonization final temperature, and keeping the first preset constant temperature time to obtain a carbonized product;
in one embodiment of the present invention, the inert atmosphere is argon.
In an embodiment of the present invention, the first predetermined temperature rise rate may be 2 to 6 ℃/min.
In an embodiment of the present invention, the final temperature of the first pre-determined carbonization may be 1000-.
In an embodiment of the present invention, the first preset constant temperature time may be 20 to 60 min.
And step S6, carrying out impregnation densification treatment on the carbonized product at a preset pressure value, maintaining the pressure for a fourth preset time, carrying out secondary carbonization at a second preset temperature rise rate after the impregnation is finished, reaching a second preset carbonization final temperature, keeping the second preset constant temperature time, carrying out graphitization treatment, keeping the third preset constant temperature time, cooling and discharging.
In one embodiment of the invention, the impregnant used in the impregnation densification treatment can be selected from modified asphalt, the softening point is 100-110 ℃, the carbon residue value is not less than 53 percent, and the ash content is not more than 0.1 percent.
In an embodiment of the present invention, the preset pressure value may be 2 to 4MPa, and the fourth preset time period may be 1 to 3 hours.
In an embodiment of the invention, the second predetermined temperature-increasing rate may be 5-10 ℃/min.
In an embodiment of the present invention, the second preset final carbonization temperature may be 1000-.
In an embodiment of the present invention, the second preset constant temperature time may be 20 to 60min, and the third preset constant temperature time may be 0.5 to 1 h.
In one embodiment of the present invention, the graphitization temperature in the graphitization treatment is controlled to 2700-.
The method for preparing the highly densified ultrafine graphite particles for use in an ionization chamber according to the present invention will now be explained and illustrated with reference to several specific examples.
Example 1
Crushing coal tar pitch with a softening point of 270 ℃ to 20 mu m, stirring the crushed coal tar pitch with toluene at the temperature of 50 ℃ for 30min, extracting insoluble substances, drying the solvent, crushing the crushed coal tar pitch to 20 mu m again, and stirring the crushed coal tar pitch and the quinoline solvent at the temperature of 50 ℃ for 30min to obtain a soluble substance solution. When the temperature of the pitch coke with the average particle size of 1 mu m in the kneader reaches 120 ℃, adding a soluble substance solution dissolved in the quinoline solvent as a binder into the kneader for liquid phase mixing for 1h, wherein the binder accounts for 35%, then heating to 260 ℃, keeping the temperature for 1h, and evaporating the solvent to obtain the paste. The paste was crushed to 5 μm to obtain a pressed powder. And (3) putting the pressed powder into a mold for pressing and forming under 200MPa, maintaining the pressure for 30min, and relieving the pressure to obtain a green body sample. And (3) carbonizing the green blank sample in argon at the heating rate of 2 ℃/min and the final carbonization temperature of 1000 ℃ for 20-60min to obtain a carbonized product. Carrying out impregnation densification treatment on the carbonized product, selecting modified asphalt as an impregnant (the softening point is 100-.
Example 2
Crushing coal tar pitch with softening point of 80 ℃ to 50 μm, stirring with acetone at 100 ℃ for 120min, extracting insoluble substances, drying solvent, crushing to 50 μm, stirring with pyridine solvent at 100 ℃ for 120min to obtain soluble substance solution. When the temperature of the pitch coke with the average particle size of 15 mu m in the kneader reaches 50 ℃, adding a soluble substance solution dissolved in a pyridine solvent as a binder into the kneader for liquid phase mixing for 3h, wherein the binder accounts for 25%, then heating to 140 ℃, keeping the temperature for 3h, and evaporating the solvent to obtain the paste. The paste was crushed to 50 μm to obtain a pressed powder. And (3) putting the pressed powder into a mold for pressing and forming under 120MPa, maintaining the pressure for 10min, and relieving the pressure to obtain a green body sample. And (3) carbonizing the green blank sample in argon at the heating rate of 6 ℃/min and the final carbonization temperature of 1050 ℃ for 60min to obtain a carbonized product. Carrying out impregnation densification treatment on the carbonized product, selecting modified asphalt as an impregnant (the softening point is 100-.
Example 3
Crushing coal tar pitch with a softening point of 110 ℃ to 30 mu m, stirring the crushed coal tar pitch with toluene at a temperature of 80 ℃ for 90min, extracting insoluble substances, drying the solvent, crushing the crushed coal tar pitch to 30 mu m again, and stirring the crushed coal tar pitch with tetrahydrofuran at a temperature of 80 ℃ for 90min to obtain a soluble substance solution. When the temperature of the pitch coke with the average particle size of 10 mu m in the kneader reaches 100 ℃, adding a soluble substance solution dissolved in a tetrahydrofuran solvent as a binder into the kneader for liquid phase mixing for 2h, wherein the binder accounts for 27%, then heating to 80 ℃, keeping the temperature for 2h, and evaporating the solvent to obtain the paste. The paste was crushed to 20 μm to obtain a pressed powder. And (3) putting the pressed powder into a die at 160MPa for compression molding, maintaining the pressure for 20min, and relieving the pressure to obtain a green body sample. And (3) carbonizing the green blank sample in argon at the heating rate of 4 ℃/min and the final carbonization temperature of 1000 ℃ for 40min to obtain a carbonized product. Carrying out impregnation densification treatment on the carbonized product, selecting modified asphalt as an impregnant (the softening point is 100-.
Example 4
Crushing coal tar pitch with softening point of 180 ℃ to 30 mu m, stirring with n-hexane at 50 ℃ for 30min, extracting insoluble substances, drying solvent, crushing again to 30 mu m, stirring with NMP at 50 ℃ for 30min to obtain soluble substance solution. Adding soluble matter solution dissolved by NMP solvent as a binder into a kneader to perform liquid phase mixing for 1h when the temperature of the pitch coke with the average particle size of 20 mu m in the kneader reaches 100 ℃, heating to 220 ℃, keeping the temperature for 3h, and evaporating the solvent to obtain the paste. The paste was crushed to 50 μm to obtain a pressed powder. And (3) putting the pressed powder into a mold for pressing and forming under 200MPa, maintaining the pressure for 30min, and relieving the pressure to obtain a green body sample. And (3) carbonizing the green blank sample in argon at the heating rate of 2 ℃/min and the final carbonization temperature of 1000 ℃ for 60min to obtain a carbonized product. Carrying out impregnation densification treatment on the carbonized product, selecting modified asphalt as an impregnant (the softening point is 100-.
Example 5
Crushing coal tar pitch with softening point of 110 ℃ to 20 mu m, stirring with acetone at 50 ℃ for 120min, extracting insoluble substances, drying solvent, crushing again to 20 mu m, and stirring with tetrahydrofuran at 50 ℃ for 120min to obtain soluble substance solution. When the temperature of petroleum coke with the average grain diameter of 3 mu m in the kneader reaches 90 ℃, adding a soluble substance solution dissolved in tetrahydrofuran solvent as a binder into the kneader for liquid phase mixing for 1h, wherein the binder accounts for 30%, then heating to 80 ℃, keeping the temperature for 2h, and evaporating the solvent to obtain the paste. The paste was crushed to 10 μm to obtain a pressed powder. And (3) putting the pressed powder into a mold for pressing and forming under 200MPa, maintaining the pressure for 30min, and relieving the pressure to obtain a green body sample. And (3) carbonizing the green blank sample in argon at the heating rate of 6 ℃/min and the final carbonization temperature of 1000 ℃ for 30min to obtain a carbonized product. Carrying out impregnation densification treatment on the carbonized product, selecting modified asphalt as an impregnant (the softening point is 100-.
Example 6
Crushing coal tar pitch with a softening point of 270 ℃ to 20 mu m, stirring the crushed coal tar pitch with benzene at the temperature of 100 ℃ for 120min, extracting insoluble substances, drying the solvent, crushing the crushed coal tar pitch to 20 mu m again, and stirring the crushed coal tar pitch with quinoline at the temperature of 100 ℃ for 120min to obtain a soluble substance solution. When the temperature of the needle coke with the average particle size of 20 mu m in the kneader reaches 120 ℃, adding a soluble substance solution dissolved in the quinoline solvent as a binder into the kneader for liquid phase mixing for 3h, wherein the binder accounts for 22%, then heating to 260 ℃, keeping the temperature for 3h, and evaporating the solvent to obtain the paste. The paste was crushed to 25 μm to obtain a pressed powder. And (3) putting the pressed powder into a mold for pressing and forming under the pressure of 180MPa, maintaining the pressure for 30min, and relieving the pressure to obtain a green body sample. And (3) carbonizing the green blank sample in argon at the heating rate of 2 ℃/min and the final carbonization temperature of 1000 ℃ for 20min to obtain a carbonized product. Carrying out impregnation densification treatment on the carbonized product, selecting modified asphalt as an impregnant (the softening point is 100-.
The basic performance indexes of the high-density ultrafine-grained graphite for the ionization chamber prepared according to the above embodiment are shown in table 1:
TABLE 1
The foregoing description is only exemplary of the preferred embodiments of the disclosure and is illustrative of the principles of the technology employed. It will be appreciated by those skilled in the art that the scope of the invention in the present disclosure is not limited to the specific combination of the above-mentioned features, but also encompasses other embodiments in which any combination of the above-mentioned features or their equivalents is possible without departing from the inventive concept. For example, the above features and (but not limited to) the features disclosed in this disclosure having similar functions are replaced with each other to form the technical solution.
Claims (10)
1. A preparation method of high-density ultrafine particle graphite for an ionization chamber is characterized by comprising the following steps:
step S1, crushing coal tar pitch, stirring the crushed coal tar pitch and a first organic solvent at the temperature of 50-100 ℃, extracting to obtain insoluble substances, drying the solvent, crushing the insoluble substances again, and fully stirring the dried insoluble substances and a second organic solvent at the temperature of 50-100 ℃ to obtain a soluble substance solution;
step S2, when the temperature of the ultrafine-particle-size aggregate carbon in the kneading machine reaches a preset temperature, adding a soluble substance solution of a second organic solvent as a binder into the kneading machine for liquid-phase mixing for a first preset time, then heating to a temperature above the boiling point of the second organic solvent, keeping the temperature for a second preset time, and evaporating the solvent to obtain a paste;
step S3, crushing the paste to obtain pressed powder;
step S4, filling the pressed powder into a die, pressing and forming under the first pressure condition, keeping the pressure for a third preset time, and relieving the pressure to obtain a green body sample;
step S5, carbonizing the green body sample in an inert atmosphere, heating at a first preset heating rate to reach a first preset carbonization final temperature, and keeping the first preset constant temperature time to obtain a carbonized product;
and step S6, carrying out impregnation densification treatment on the carbonized product at a preset pressure value, maintaining the pressure for a fourth preset time, carrying out secondary carbonization at a second preset temperature rise rate after the impregnation is finished, reaching a second preset carbonization final temperature, keeping the second preset constant temperature time, carrying out graphitization treatment, keeping the third preset constant temperature time, cooling and discharging.
2. The method according to claim 1, wherein in step S1, the coal tar pitch is crushed into 20-50 μm fragments, and is mixed with the first organic solvent at 50-100 ℃ for 30-120min, the insoluble substance is extracted by vacuum filtration using a buchner funnel, and after drying the solvent, the insoluble substance is crushed again into 20-50 μm fragments, and is mixed with the second organic solvent at 50-100 ℃ for 30-120 min.
3. The method according to claim 1 or 2, wherein the first organic solvent is a mixture of one or more of the following solvents: toluene, benzene, n-hexane, acetone; and/or the second organic solvent is a mixed solution of one or more of the following solvents: quinoline, pyridine, azomethyl pyrrolidone and tetrahydrofuran.
4. The method as claimed in claim 1, wherein in step S2, when the temperature of the ultra-fine particle size aggregate carbon in the kneader reaches 50-120 ℃, a soluble substance solution of a second organic solvent is added as a binder into the kneader for liquid phase mixing for 1-3h, then the temperature is raised to a temperature higher than the boiling point of the second organic solvent, the temperature is kept constant for 1-3h, and the solvent is evaporated to obtain the paste.
5. The method of claim 1 or 4, wherein the aggregate char is pitch coke, petroleum coke, or needle coke.
6. The method according to claim 1 or 4, wherein the second organic solvent soluble substance accounts for 22-35% of the total mass of the mixed raw material consisting of the second organic solvent soluble substance and the aggregate carbon.
7. The method of claim 1, wherein in step S3, the paste is crushed to a size of 5-50 μ ι η.
8. The method according to claim 1, wherein in step S4, the pressed powder is filled into a mold, and is pressed into a molded product under the pressure of 200MPa for 10-30min, and a green sample is obtained after pressure relief.
9. The method as claimed in claim 1, wherein in step S5, the green compact sample is carbonized in argon gas, and the temperature is raised at a rate of 2-6 ℃/min to reach a final carbonization temperature of 1000-1050 ℃, and is maintained for 20-60min to obtain a carbonized product.
10. The method according to claim 1, wherein in step S6, the carbonized product is subjected to impregnation densification treatment under 2-4MPa, and pressure is maintained for 1-3h, after the impregnation is completed, secondary carbonization is performed at a preset temperature rise rate of 5-10 ℃/min to reach a second preset carbonization final temperature of 1000-.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116354741A (en) * | 2022-12-21 | 2023-06-30 | 中国人民解放军96901部队23分队 | Method for preparing low-density hierarchical pore isostatic pressing graphite material by template method |
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