Mesophase pitch-based graphite and Joule hot pressed sintering preparation method thereof

Abstract

The invention belongs to the technical field of nonmetal material processing, and particularly relates to mesophase pitch-based graphite and a Joule hot pressing sintering preparation method thereof. A Joule hot pressing sintering process is adopted, mesophase pitch is used as a carbon source, mesophase pitch-based carbon powder obtained through low-temperature carbonization is used as a sintering raw material, and a proper amount of carbon powder is weighed and put into a mold of Joule hot pressing equipment to reach a certain thickness; the method comprises the following steps: compacting carbon powder through pressurization, and sintering and graphitizing the carbon powder in a Joule heat heating manner to finally obtain the mesophase pitch-based graphite block with the density of 2.19 g / cm < 3 >. Compared with traditional hot pressing sintering, the graphite prepared through the Joule hot pressing sintering technology has the advantages that the density is high, graphite defects are low, too many complex processes are not needed, the density is high once the graphite is prepared, and the preparation time is short compared with traditional sintering time; and a reference is provided for a method for densifying mesophase pitch-based graphite and reducing graphite defects.

Description

Technical Field

[0001] The invention belongs to the technical field of graphite preparation, and in particular relates to a method for preparing graphite material by sintering mesophase pitch-based carbon as a raw material through Joule hot pressing. Background Art

[0002] Mesophase pitch is easy to graphitize and has excellent orientation. It is widely used as the matrix carbon of high thermal conductivity carbon / carbon composite materials. It has excellent thermal conductivity and is an important raw material for high thermal conductivity materials. However, it is difficult for mesophase pitch-based carbon to form a densified block because the mesophase pitch easily expands during the carbonization process, causing many voids, making it difficult to densify, which in turn greatly reduces the material performance. Hot pressing sintering is a process in which pressure is applied to the sintered powder in a mold and the temperature is raised for sintering. This process is mainly heated by graphite sheets, which results in a very slow heating process. At the same time, the powder is heated for a long time due to uneven heating, so that the sintering cycle of the entire powder is long. For the sintering of amorphous carbon powder, some binders are often added and then sintered, but the performance of the sintered material is not particularly good, and the process is cumbersome and complicated. At present, the graphite directly hot-pressed by sintering amorphous carbon powder has problems such as low density and high graphite defects. Summary of the invention

[0003] One of the purposes of the present invention is to provide a method for preparing mesophase asphalt-based graphite sintered by Joule heat. The method performs Joule hot pressing and sintering on the mesophase asphalt-based carbon powder after low-temperature carbonization. The gaps between the carbon powders are reduced by cold pressing, and the contact between them is closer. Then, an electric current is passed through the compacted carbon powder by Joule heat. After heat is generated inside the carbon powder due to atomic vibration, the temperature rises rapidly to a very high temperature, thereby graphitizing and densifying the low-temperature carbonized carbon powder. The density of the obtained graphite material reaches 2.19g / cm 3 Obviously higher than the 1.86g / cm prepared by traditional hot pressing 3 High, while the defects of graphite are greatly reduced.

[0004] To achieve the above object, the present invention adopts the following technical scheme: a method for preparing mesophase asphalt-based graphite, comprising the following steps:

[0005] Step A, putting the mesophase pitch into a graphite boat, and then putting them into a quartz glass tube furnace together, performing low-temperature carbonization in a protective atmosphere, and taking them out after cooling to obtain expanded low-temperature pitch carbon;

[0006] Step B, crushing the expanded low-temperature asphalt carbon to obtain carbon powder with a particle size of 2-20 μm;

[0007] Step C, putting carbon powder into a Joule hot pressing mold, calculating the mass of carbon powder required for hot pressing a sintered material of a specific thickness according to the size of the mold, weighing the required carbon powder and putting it into the mold for pre-compaction;

[0008] Step D, transfer the pre-compacted mold to a Joule hot pressing device, pressurize it under a vacuum environment, maintain the set pressure after the pressure reaches the set value, and perform Joule heat heating. When the temperature reaches the set temperature of 1500-2500°C, stop heating and keep it warm for 0.5-60 minutes. After cooling to room temperature, release the pressure to obtain an intermediate phase asphalt-based graphite block.

[0009] Further improvement of the preparation method of mesophase asphalt-based graphite:

[0010] Preferably, the heating rate of the low-temperature carbonization in step A is 0.1-5°C / min, the temperature of the low-temperature carbonization is 500-1100°C, and the holding time is 0.5-120 min.

[0011] Preferably, in step B, the asphalt carbon is crushed at a rotation speed of 200 to 800 r / min for 15 to 300 s.

[0012] Preferably, in step B, the asphalt carbon is crushed at a rotation speed of 250 r / min for 30 seconds.

[0013] Preferably, in step C, the thickness of the hot-pressed sintered material is 1-5 mm, and the amount of mesophase pitch used is 1-50 g.

[0014] Preferably, in step C, the pressure at which the carbon powder is pre-compacted in the mold is 5-20 MPa.

[0015] Preferably, in step D, the pre-compacted mold is transferred to a Joule hot press device, and the pressure is increased at a rate of 1 to 5 MPa / s to reach a set pressure of 5 to 50 MPa.

[0016] Preferably, the Joule heat heating rate in step D is 1500-4000° C. / min.

[0017] Preferably, the Joule hot pressing device in step D is a hot pressing Joule meter produced by Hefei Yuansitu Technology Co., Ltd., with a rated power of 60KW, a voltage of 380V, a frequency of 50HZ, and three phases.

[0018] A second object of the present invention is to provide a mesophase asphalt-based graphite obtained by the preparation method of the mesophase asphalt-based graphite described in any one of the above.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1) The present invention provides a preparation method of mesophase pitch-based graphite sintering, which adopts Joule hot pressing sintering process, uses mesophase pitch as a carbon source and undergoes low-temperature carbonization to obtain mesophase pitch-based carbon powder as a sintering raw material, weighs a certain mass of carbon powder to achieve a certain thickness and puts it into a mold of a Joule hot pressing device, first pressurizes the carbon powder to make it dense, and then sinters the carbon powder by Joule heat heating to graphitize it, and finally achieves a density of 2.19g / cm 3 Mesophase asphalt-based graphite block. Compared with traditional hot pressing sintering, the graphite prepared by the Joule hot pressing sintering process of the present invention has higher density and lower graphite defects, does not require too many complicated processes, and has a very high density once prepared. The preparation time is much shorter than the traditional sintering time, and provides a reference for the densification of mesophase asphalt-based graphite and the method of reducing graphite defects.

[0021] 2) The embodiment of the present invention not only has a simple preparation process, an easy-to-control reaction process, and a short production cycle, but also the prepared mesophase pitch-based graphite has a good density and low graphite defects. It is a new process that is significantly superior to the traditional hot-pressing sintering of mesophase pitch-based graphite. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0023] Figure 1 The scanning electron microscope photographs are obtained by using a scanning electron microscope to detect the morphology of the mesophase asphalt-based graphite blocks prepared in Examples 1, 4, 5, 6 of the present invention and Comparative Examples 1 and 2.

[0024] Figure 2 Raman comparison graphs were detected for the interphase asphalt-based graphite blocks prepared in Examples 1, 4, 5, 6 and Comparative Examples 1 and 2. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present invention.

[0026] Example 1

[0027] This embodiment provides a method for preparing mesophase pitch-based graphite sintering, which specifically includes the following steps:

[0028] Step a1, weigh 25g of mesophase asphalt and put it into a graphite boat, and then put them into a quartz glass tube furnace, under nitrogen (N2≥99.999%) atmosphere, the heating rate is 2°C / min, the temperature is raised to 700°C for low-temperature carbonization, the heat preservation time is 1min, and the expanded low-temperature asphalt carbon is obtained after cooling;

[0029] Step b1, adding the expanded low-temperature asphalt carbon into a crusher, crushing the asphalt carbon at 250 r / min for 30 seconds to obtain carbon powder with a particle size of 2 to 20 μm.

[0030] Step c1, putting the crushed carbon powder into a Joule hot pressing mold, calculating the mass of carbon powder required for hot pressing 1mm thick sintered material according to the size of the mold, weighing the required amount and putting it into the mold for pre-compaction;

[0031] Step d1, transfer the pre-compacted mold to a Joule hot pressing device (Hot Pressing Joule Meter produced by Hefei In-Situ Technology Co., Ltd., rated power 60KW, voltage 380V, frequency 50HZ, three-phase), press at a pressure of 50MPa, and after the pressure reaches the set value, heat up to 2100℃ at a rate of 2000℃ / min, and keep warm for 120s, and finally cool naturally to room temperature to obtain a mesophase asphalt-based graphite block, which is not agglomerated as a whole and has a density of less than 1.85g / cm 3 .

[0032] Example 2

[0033] This embodiment provides a method for preparing mesophase pitch-based graphite sintering, which specifically includes the following steps:

[0034] Step a1, weigh 25g of mesophase asphalt and put it into a graphite boat, and then put them into a quartz glass tube furnace, under nitrogen (N2≥99.999%) atmosphere, the heating rate is 2°C / min, the temperature is raised to 700°C for low-temperature carbonization, the heat preservation time is 1min, and the expanded low-temperature asphalt carbon is obtained after cooling;

[0035] Step b1, adding the expanded low-temperature asphalt carbon into a crusher, crushing the asphalt carbon at 250 r / min for 30 seconds to obtain carbon powder with a particle size of 2 to 20 μm.

[0036] Step c1, putting the crushed carbon powder into a Joule hot pressing mold, calculating the mass of carbon powder required for hot pressing a 3mm thick sintered material according to the size of the mold, weighing the required amount and putting it into the mold for pre-compaction;

[0037] Step d1, transfer the pre-compacted mold to a Joule hot pressing device (Hot Pressing Joule Meter produced by Hefei In-Situ Technology Co., Ltd., rated power 60KW, voltage 380V, frequency 50HZ, three-phase), press at a pressure of 50MPa, and after the pressure reaches the set value, heat up to 2100℃ at a rate of 2000℃ / min, and keep warm for 120s, and finally cool naturally to room temperature to obtain a mesophase asphalt-based graphite block, which is a whole block with a density of 1.97g / cm 3 .

[0038] Example 3

[0039] This embodiment provides a method for preparing mesophase pitch-based graphite sintering, which specifically includes the following steps:

[0040] Step a1, weigh 25g of mesophase asphalt and put it into a graphite boat, and then put them into a quartz glass tube furnace, under nitrogen (N2≥99.999%) atmosphere, the heating rate is 2°C / min, the temperature is raised to 700°C for low-temperature carbonization, the heat preservation time is 1min, and the expanded low-temperature asphalt carbon is obtained after cooling;

[0041] Step b1, adding the expanded low-temperature asphalt carbon into a crusher, crushing the asphalt carbon at 250 r / min for 30 seconds to obtain carbon powder with a particle size of 2 to 20 μm.

[0042] Step c1, putting the crushed carbon powder into a Joule hot pressing mold, calculating the mass of carbon powder required for hot pressing a 5mm thick sintered material according to the size of the mold, weighing the required amount and putting it into the mold for pre-compaction;

[0043] Step d1, transfer the pre-compacted mold to a Joule hot pressing device (Hot Pressing Joule Meter produced by Hefei In-Situ Technology Co., Ltd., rated power 60KW, voltage 380V, frequency 50HZ, three-phase), press at a pressure of 50MPa, and after the pressure reaches the set value, heat up to 2100℃ at a rate of 2000℃ / min, and keep warm for 120s, and finally cool naturally to room temperature to obtain a mesophase asphalt-based graphite block, which is not agglomerated as a whole and has a density of less than 1.85g / cm 3 .

[0044] Example 4

[0045] This embodiment provides a method for preparing mesophase pitch-based graphite sintering, which specifically includes the following steps:

[0046] Step a1, weigh 25g of mesophase asphalt and put it into a graphite boat, and then put them into a quartz glass tube furnace, under nitrogen (N2≥99.999%) atmosphere, the heating rate is 2°C / min, the temperature is raised to 700°C for low-temperature carbonization, the heat preservation time is 1min, and the expanded low-temperature asphalt carbon is obtained after cooling;

[0047] Step b1, adding the expanded low-temperature asphalt carbon into a crusher, crushing the asphalt carbon at 250 r / min for 30 seconds to obtain carbon powder with a particle size of 2 to 20 μm.

[0048] Step c1, putting the crushed carbon powder into a Joule hot pressing mold, calculating the mass of carbon powder required for hot pressing a 3mm thick sintered material according to the size of the mold, weighing the required amount and putting it into the mold for pre-compaction;

[0049] Step d1, transfer the pre-compacted mold to a Joule hot pressing device (Hot Pressing Joule Meter produced by Hefei Yuanzui Technology Co., Ltd., rated power 60KW, voltage 380V, frequency 50HZ, three-phase), press at a pressure of 50Mpa, and after the pressure reaches the set value, heat up to 2100℃ at a rate of 2000℃ / s, and keep warm for 180s, and finally cool naturally to room temperature to obtain a mesophase asphalt-based graphite block, which is a whole block with a density of 2.01g / cm 3 .

[0050] Example 5

[0051] This embodiment provides a method for preparing mesophase pitch-based graphite sintering, which specifically includes the following steps:

[0052] Step a1, weigh 25g of mesophase asphalt and put it into a graphite boat, and then put them into a quartz glass tube furnace, under nitrogen (N2≥99.999%) atmosphere, the heating rate is 2°C / min, the temperature is raised to 700°C for low-temperature carbonization, the heat preservation time is 1min, and the expanded low-temperature asphalt carbon is obtained after cooling;

[0053] Step b1, adding the expanded low-temperature asphalt carbon into a crusher, crushing the asphalt carbon at 250 r / min for 30 seconds to obtain carbon powder with a particle size of 2 to 20 μm.

[0054] Step c1, putting the crushed carbon powder into a Joule hot pressing mold, calculating the mass of carbon powder required for hot pressing a 3mm thick sintered material according to the size of the mold, weighing the required amount and putting it into the mold for pre-compaction;

[0055] Step d1, transfer the pre-compacted mold to a Joule hot pressing device (Hot Pressing Joule Meter produced by Hefei In-Situ Technology Co., Ltd., rated power 60KW, voltage 380V, frequency 50HZ, three-phase), press at a pressure of 50Mpa, and after the pressure reaches the set value, heat up to 2100℃ at a rate of 2000℃ / s, and keep warm for 300s, and finally cool naturally to room temperature to obtain a mesophase asphalt-based graphite block, which is a whole block with a density of 2.19g / cm 3 .

[0056] Example 6

[0057] This embodiment provides a method for preparing mesophase pitch-based graphite sintering, which specifically includes the following steps:

[0058] This embodiment provides a method for preparing mesophase pitch-based graphite sintering, which specifically includes the following steps:

[0059] Step a1, weigh 25g of mesophase asphalt and put it into a graphite boat, and then put them into a quartz glass tube furnace, under nitrogen (N2≥99.999%) atmosphere, the heating rate is 2°C / min, the temperature is raised to 700°C for low-temperature carbonization, the heat preservation time is 1min, and the expanded low-temperature asphalt carbon is obtained after cooling;

[0060] Step b1, adding the expanded low-temperature asphalt carbon into a crusher, crushing the asphalt carbon at 250 r / min for 30 seconds to obtain carbon powder with a particle size of 2 to 20 μm.

[0061] Step c1, putting the crushed carbon powder into a Joule hot pressing mold, calculating the mass of carbon powder required for hot pressing a 3mm thick sintered material according to the size of the mold, weighing the required amount and putting it into the mold for pre-compaction;

[0062] Step d1, transfer the pre-compacted mold to a Joule hot pressing device (Hot Pressing Joule Meter produced by Hefei Yuanzui Technology Co., Ltd., rated power 60KW, voltage 380V, frequency 50HZ, three-phase), press at a pressure of 50Mpa, and after the pressure reaches the set value, heat up to 2100℃ at a rate of 2000℃ / s, and keep warm for 480s, and finally cool naturally to room temperature to obtain a mesophase asphalt-based graphite block, which is a whole block with a density of 2.18g / cm 3 .

[0063] Example 7

[0064] This embodiment provides a method for preparing mesophase pitch-based graphite sintering, which specifically includes the following steps:

[0065] Step a1, weigh 25g of mesophase asphalt and put it into a graphite boat, and then put them into a quartz glass tube furnace, under nitrogen (N2≥99.999%) atmosphere, the heating rate is 2°C / min, the temperature is raised to 700°C for low-temperature carbonization, the heat preservation time is 1min, and the expanded low-temperature asphalt carbon is obtained after cooling;

[0066] Step b1, adding the expanded low-temperature asphalt carbon into a crusher, crushing the asphalt carbon at 250 r / min for 30 seconds to obtain carbon powder with a particle size of 2 to 20 μm.

[0067] Step c1, putting the crushed carbon powder into a Joule hot pressing mold, calculating the mass of carbon powder required for hot pressing a 3mm thick sintered material according to the size of the mold, weighing the required amount and putting it into the mold for pre-compaction;

[0068] Step d1, transfer the pre-compacted mold to a Joule hot pressing device (Hot Pressing Joule Meter produced by Hefei In-Situ Technology Co., Ltd., rated power 60KW, voltage 380V, frequency 50HZ, three-phase), press at a pressure of 50MPa, and after the pressure reaches the set value, heat up to 1500℃ at a rate of 2000℃ / min, and keep warm for 120s, and finally cool naturally to room temperature to obtain a mesophase asphalt-based graphite block, which is not agglomerated as a whole and has a density of less than 1.85g / cm 3 .

[0069] Example 8

[0070] This embodiment provides a method for preparing mesophase pitch-based graphite sintering, which specifically includes the following steps:

[0071] Step a1, weigh 25g of mesophase asphalt and put it into a graphite boat, and then put them into a quartz glass tube furnace, under nitrogen (N2≥99.999%) atmosphere, the heating rate is 2°C / min, the temperature is raised to 700°C for low-temperature carbonization, the heat preservation time is 1min, and the expanded low-temperature asphalt carbon is obtained after cooling;

[0072] Step b1, adding the expanded low-temperature asphalt carbon into a crusher, crushing the asphalt carbon at 250 r / min for 30 seconds to obtain carbon powder with a particle size of 2 to 20 μm.

[0073] Step c1, putting the crushed carbon powder into a Joule hot pressing mold, calculating the mass of carbon powder required for hot pressing a 3mm thick sintered material according to the size of the mold, weighing the required amount and putting it into the mold for pre-compaction;

[0074] Step d1, transfer the pre-compacted mold to a Joule hot pressing device (Hot Pressing Joule Meter produced by Hefei In-Situ Technology Co., Ltd., rated power 60KW, voltage 380V, frequency 50HZ, three-phase), press at a pressure of 50MPa, and after the pressure reaches the set value, heat up to 1800℃ at a rate of 2000℃ / min, and keep warm for 120s, and finally cool naturally to room temperature to obtain a mesophase asphalt-based graphite block, which is not agglomerated as a whole and has a density of less than 1.85g / cm 3 .

[0075] Example 9

[0076] This embodiment provides a method for preparing mesophase pitch-based graphite sintering, which specifically includes the following steps:

[0077] Step a1, weigh 25g of mesophase asphalt and put it into a graphite boat, and then put them into a quartz glass tube furnace, under nitrogen (N2≥99.999%) atmosphere, the heating rate is 2°C / min, the temperature is raised to 700°C for low-temperature carbonization, the heat preservation time is 1min, and the expanded low-temperature asphalt carbon is obtained after cooling;

[0078] Step b1, adding the expanded low-temperature asphalt carbon into a crusher, crushing the asphalt carbon at 250 r / min for 30 seconds to obtain carbon powder with a particle size of 2 to 20 μm.

[0079] Step c1, putting the crushed carbon powder into a Joule hot pressing mold, calculating the mass of carbon powder required for hot pressing a 3mm thick sintered material according to the size of the mold, weighing the required amount and putting it into the mold for pre-compaction;

[0080] Step d1, transfer the pre-compacted mold to a Joule hot pressing device (Hot Pressing Joule Meter produced by Hefei In-Situ Technology Co., Ltd., rated power 60KW, voltage 380V, frequency 50HZ, three-phase), press at a pressure of 50MPa, and after the pressure reaches the set value, heat to 2000℃ at a rate of 2000℃ / min, and keep warm for 120s, and finally cool naturally to room temperature to obtain a mesophase asphalt-based graphite block, which is not agglomerated as a whole and has a density of less than 1.85g / cm 3 .

[0081] Comparative Example 1

[0082] A method for preparing sintered mesophase pitch-based graphite may include the following steps:

[0083] Step a1, weigh 25g of mesophase asphalt and put it into a graphite boat, and then put them into a quartz glass tube furnace, under nitrogen (N2≥99.999%) atmosphere, the heating rate is 2°C / min, the temperature is raised to 700°C for low-temperature carbonization, the heat preservation time is 1min, and the expanded low-temperature asphalt carbon is obtained after cooling;

[0084] Step b1, adding the expanded low-temperature asphalt carbon into a crusher, crushing the asphalt carbon at 250 r / min for 30 seconds to obtain carbon powder with a particle size of 2 to 20 μm.

[0085] Step c1, putting the crushed carbon powder into a Joule hot pressing mold, calculating the mass of carbon powder required for hot pressing a 3mm thick sintered material according to the size of the mold, weighing the required amount and putting it into the mold for pre-compaction;

[0086] Step d1, transfer the pre-compacted mold to a Joule hot pressing device (Hot Pressing Joule Meter produced by Hefei In-Situ Technology Co., Ltd., rated power 60KW, voltage 380V, frequency 50HZ, three-phase), press at a pressure of 50Mpa, and after the pressure reaches the set value, heat up to 2100℃ at a rate of 2000℃ / s, keep warm for 60s, and finally cool naturally to room temperature to obtain a mesophase asphalt-based graphite block with a density of 1.89g / cm 3 .

[0087] Comparative Example 2

[0088] A method for preparing sintered mesophase pitch-based graphite may include the following steps:

[0089] Step a1, weigh 25g of mesophase asphalt and put it into a graphite boat, and then put them into a quartz glass tube furnace, under nitrogen (N2≥99.999%) atmosphere, the heating rate is 2°C / min, the temperature is raised to 700°C for low-temperature carbonization, the heat preservation time is 1min, and the expanded low-temperature asphalt carbon is obtained after cooling;

[0090] Step b1, adding the expanded low-temperature asphalt carbon into a crusher, crushing the asphalt carbon at 250 r / min for 30 seconds to obtain carbon powder with a particle size of 2 to 20 μm.

[0091] Step c1, putting the crushed carbon powder into a hot pressing mold, calculating the mass of carbon powder required for hot pressing 3mm thick sintered material according to the size of the mold, weighing the required amount and putting it into the mold for pre-compaction;

[0092] Step d1, transfer the pre-compacted mold to a common hot pressing device (vacuum hot pressing sintering system produced by Shanghai Chenhua Technology Co., Ltd., model ZT-60-22Y, rated power 60KW, voltage 380V, frequency 50HZ, three-phase), press at a pressure of 50Mpa, and after the pressure reaches the set value, heat up to 2100℃ at a rate of 2000℃ / s, and keep warm for 1h, and finally cool naturally to room temperature to obtain a mesophase asphalt-based graphite block with a density of 1.85g / cm 3 .

[0093] Morphology observation and density and graphite defect characterization

[0094] The hot pressing thickness of the sintered materials in Examples 1, 2, and 3 were 1 mm, 3 mm, and 5 mm, respectively. The other process conditions were the same (in a Joule hot pressing device, heat preservation at 2100°C for 120 s). The densities of the obtained mesophase asphalt-based graphite blocks were 1.85 g / cm 3 , 1.97g / cm 3 and 1.85g / cm 3 From the comparison of Examples 1-3, it can be seen that the hot pressing thickness of the sintered material has a certain influence on the sintering effect of the material. When the hot pressing thickness of the sintered material is controlled at about 3 mm, the sintering effect is better. Under the hot pressing thickness of Examples 1 and 3, the mesophase asphalt-based graphite finally obtained does not form a block as a whole.

[0095] The hot-pressed thickness of the sintered materials in Examples 2, 7, 8, and 9 was 3 mm. The sintered materials were placed in a Joule hot press and kept at 2100°C, 1500°C, 1800°C, and 2000°C for 120 seconds. Only the mesophase asphalt-based graphite blocks prepared at 2100°C formed blocks with a density higher than 1.85 g / cm 3 Reached 1.97g / cm 3 ; From the comparison of Examples 2, 7, 8, and 9, it can be seen that as the Joule hot pressing sintering temperature increases to 2100°C, the sintering effect of the mesophase asphalt-based graphite block can be well reflected, among which 2100°C is the optimal Joule hot pressing sintering temperature.

[0096] The mesophase asphalt-based graphites obtained in Examples 1, 4, 5, 6 of the present invention and Comparative Examples 1 and 2 were subjected to morphological observation and density and graphite defect characterization, thereby obtaining the following results:

[0097] (1) The morphology of the mesophase asphalt-based graphite prepared in Examples 1, 4, 5, 6 and Comparative Example 1 and Comparative Example 2 of the present invention was detected by scanning electron microscopy, and the following was obtained: Figure 1 The scanning electron microscope photo shown. Figure 1 (a) is a FESEM photograph of the mesophase asphalt-based graphite prepared in Example 1 of the present invention at a magnification of 500; Figure 1 (b) is a FESEM photograph of the interphase asphalt-based graphite prepared in Example 4 of the present invention at a magnification of 500; Figure 1 (c) is a FESEM photograph of the interphase asphalt-based graphite prepared in Example 5 of the present invention at a magnification of 500; Figure 1 (d) is a FESEM photograph of the interphase asphalt-based graphite prepared in Example 6 of the present invention at a magnification of 500; Figure 1 (e) is a FESEM photograph of the substrate prepared in Comparative Example 1 of the present invention at a magnification of 500; Figure 1 (f) is a FESEM photo of the substrate prepared in comparative example 2 of the present invention at a magnification of 500. Examples 1, 4, 5, and 6 are respectively the cases where the Joule hot pressing holding time is 120s, 180s, 300s, and 480s, while comparative examples 1 and 2 are the cases where the Joule hot pressing holding time is 60s and the hot pressing sintering is 1h. Figure 1 It can be seen that as the Joule hot pressing sintering holding time increases, the sintering of the mesophase pitch-based graphite becomes stronger and the graphite density increases. Among them, the material density of Example 4 reaches the best; the sintering effects of Comparative Examples 1 and 2 are not ideal.

[0098] (2) The spectrum of graphite is collected using a confocal Raman system with an excitation wavelength of 532 nm, thereby obtaining the following: Figure 2 Raman spectrum shown. Figure 2 is the Raman spectrum of the mesophase asphalt-based graphite prepared in Examples 1, 4, 5, 6 and Comparative Examples 1 and 2 of the present invention; Figure 2 It can be seen that the intensity ratio of the D peak and the G peak in the Raman spectrum of the intermediate phase asphalt-based graphite prepared in Example 6 of the present invention is the smallest, which proves the lowest graphite defects. At the same time, the intermediate phase asphalt-based graphite prepared in Comparative Example 2 has the highest graphite defects among all materials, and Comparative Example 1 is the second highest.

[0099] In summary, the embodiments of the present invention not only have a simple preparation process, an easy-to-control reaction process, and a short production cycle, but also the prepared mesophase asphalt-based graphite takes less time than traditional hot pressing and sintering, has better density, and lower graphite defects.

[0100] Those skilled in the art should understand that the above are only some specific embodiments of the present invention, rather than all embodiments. It should be noted that for those of ordinary skill in the art, many modifications and improvements can be made, and all modifications or improvements that do not exceed the scope of protection of the present invention should be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing mesophase pitch-based graphite by Joule hot pressing sintering, characterized in that: The following steps are involved: Step A, putting the mesophase pitch into a graphite boat, and then putting them into a quartz glass tube furnace together, performing low-temperature carbonization in a protective atmosphere, and taking them out after cooling to obtain expanded low-temperature pitch carbon; Step B, crushing the expanded low-temperature asphalt carbon to obtain carbon powder with a particle size of 2-20 μm; Step C, putting carbon powder into a Joule hot pressing mold, calculating the mass of carbon powder required for hot pressing a sintered material of a specific thickness according to the size of the mold, weighing the required carbon powder and putting it into the mold for pre-compaction; Step D, transfer the pre-compacted mold to a Joule hot pressing device, pressurize it under a vacuum environment, maintain the set pressure after the pressure reaches the set value, and perform Joule heat heating. When the temperature reaches the set temperature of 1500-2500°C, stop heating and keep it warm for 0.5-60 minutes. After cooling to room temperature, release the pressure to obtain an intermediate phase asphalt-based graphite block.

2. The method for preparing mesophase pitch-based graphite by Joule hot pressing and sintering according to claim 1, characterized in that: In step A, the heating rate of low-temperature carbonization is 0.1-5°C / min, the temperature of low-temperature carbonization is 500-1100°C, and the holding time is 0.5-120min.

3. The method for preparing mesophase pitch-based graphite by Joule hot pressing and sintering according to claim 1, characterized in that: In step B, the asphalt carbon is crushed at a rotation speed of 200 to 800 r / min for 15 to 300 seconds.

4. The method for preparing mesophase pitch-based graphite by Joule hot pressing and sintering according to claim 1, characterized in that: In step B, the asphalt carbon is crushed at a rotation speed of 250 r / min for 30 seconds.

5. The method for preparing mesophase pitch-based graphite by Joule hot pressing sintering according to claim 1, characterized in that: In step C, the thickness of the hot-pressed sintered material is 1-5 mm, and the amount of mesophase pitch used is 1-50 g.

6. The method for preparing mesophase pitch-based graphite by Joule hot pressing sintering according to claim 1, characterized in that: In step C, the carbon powder is placed in the mold for pre-compaction at a pressure of 5-20 MPa.

7. The method for preparing mesophase pitch-based graphite by Joule hot pressing and sintering according to claim 1, characterized in that: In step D, the pre-compacted mold is transferred to a Joule hot press device, and the pressure is increased at a rate of 1 to 5 MPa / s to reach a set pressure of 5 to 50 MPa.

8. The method for preparing mesophase pitch-based graphite by Joule hot pressing sintering according to claim 1, characterized in that: The Joule heat heating rate in step D is 1500-4000° C. / min.

9. The method for preparing mesophase pitch-based graphite by Joule hot pressing sintering according to claim 1, characterized in that: The Joule hot pressing device in step D is a hot pressing Joule meter produced by Hefei Yuansitu Technology Co., Ltd., with a rated power of 60KW, a voltage of 380V, a frequency of 50HZ, and three phases.

10. A mesophase pitch-based graphite obtained by the Joule hot pressing and sintering preparation method of the mesophase pitch-based graphite according to any one of claims 1 to 9.

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