High-strength graphite crucible and preparation method thereof

Abstract

The invention relates to the technical field of graphite crucibles, and provides a high-strength graphite crucible and a preparation method thereof. The high-strength graphite crucible is prepared from, by weight, 70-80 parts of graphitized coke, 15-20 parts of medium-temperature pitch and 5-10 parts of modified pitch, the modified pitch is composed of first modified pitch and second modified pitch, and the first modified pitch and the second modified pitch are different in needle penetration. According to the technical scheme, the problem of insufficient strength of the graphite crucible in the prior art is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of graphite crucibles, and specifically, to a high-strength graphite crucible and a preparation method thereof. Background Art

[0002] Graphite crucibles are a type of crucibles made mainly of graphite. They have good thermal conductivity and high temperature resistance. During high-temperature use, they have a small coefficient of thermal expansion, certain anti-strain performance against rapid heating and cooling, strong corrosion resistance to acidic and alkaline solutions, and excellent chemical stability; they are applied in fields such as metal casting and chemical synthesis.

[0003] With the continuous development of modern industry, the performance requirements for graphite crucibles are also increasing day by day. Among them, strength is one of the key indicators for measuring the quality and service life of graphite crucibles. However, existing graphite crucibles generally have the problem of insufficient strength. Traditional preparation processes and raw material formulas make the internal structure of graphite crucibles not dense enough, with more pores and defects, which greatly reduces their ability to resist external forces. If a graphite crucible does not have high strength, it is not only prone to deformation, cracking, etc. in a high-temperature environment, shortening the service life of the graphite crucible, increasing production costs, but also may cause material leakage, trigger safety accidents, affect the continuity and stability of production, and at the same time pose potential hazards to the surrounding environment.

[0004] Therefore, it is necessary to develop a high-strength graphite crucible. Summary of the Invention

[0005] The present invention provides a high-strength graphite crucible and a preparation method thereof, which solve the problem of insufficient strength of graphite crucibles in related technologies.

[0006] The technical solution of the present invention is as follows: The present invention provides a high-strength graphite crucible, which comprises the following raw material components in parts by weight: 70 - 80 parts of graphitized coke, 15 - 20 parts of medium-temperature pitch, and 5 - 10 parts of modified pitch. The modified pitch is composed of first modified pitch and second modified pitch, and the penetration degrees of the first modified pitch and the second modified pitch are different.

[0007] As a further technical solution, the softening point of the medium-temperature pitch is 80 - 90 °C.

[0008] As a further technical solution, the penetration degree of the first modified pitch is 45 mm, the penetration degree of the second modified pitch is 90 mm, and the mass ratio of the first modified pitch to the second modified pitch is 3 - 4:1, such as 3:1, 3.2:1, 3.4:1, 3.6:1, 3.8:1, 4:1, and preferably 4:1.

[0009] In the present invention, when the first modified pitch and the second modified pitch are combined in a mass ratio of 3 - 4:1, the performance advantages of the two pitches are fully exerted and synergistic with each other; the first modified pitch with a smaller penetration provides higher hardness, rigidity, abrasion resistance, and initial adhesion, and quickly fixes particles such as graphitized coke during the crucible forming process; the second modified pitch with a larger penetration fills the voids between particles with good fluidity and provides toughness to absorb external impact energy, enhancing the strength of the graphite crucible.

[0010] As a further technical solution, the grading method of the graphitized coke is a three - stage continuous grading, and the three - stage continuous grading includes 0 - 2 mm, 2 - 5 mm, and 5 - 8 mm, and the mass ratio of each stage is 17 - 19:1:1. For example, it can be 17:1:1, 17.5:1:1, 18:1:1, 18.5:1:1, 19:1:1, and preferably 18:1:1.

[0011] In the present invention, the graphitized coke with a three - stage continuous grading can make particles of different particle sizes fill each other, forming a more compact packing structure. The appropriate grading and mass ratio enable the graphitized coke to have better fluidity and plasticity during the process of preparing the crucible. In the forming process, it can be more evenly distributed in the mold cavity, facilitating the forming operation and being conducive to obtaining a graphite crucible with regular shape and high dimensional accuracy.

[0012] The present invention also proposes a preparation method of a high - strength graphite crucible for preparing the high - strength graphite crucible described above, which includes the following steps: adding graphitized coke to medium - temperature pitch and modified pitch for kneading, cooling, and forming to obtain a semi - finished product. After the semi - finished product is impregnated, calcined, and graphitized, the graphite crucible is obtained.

[0013] As a further technical solution, the temperature of the kneading is 145 - 150 °C, preferably 150 °C, and the time of the kneading is 70 - 80 min. For example, it can be 70 min, 72 min, 75 min, 78 min, 80 min, and preferably 70 min.

[0014] In the present invention, the kneading temperature of 145 - 150 °C enables the medium - temperature pitch and the modified pitch to reach a suitable softening state, having good fluidity, and can better penetrate to the surface and pores of the graphitized coke particles, fully wrapping each particle, thereby enhancing the adhesion between particles. Selecting the appropriate kneading temperature and time avoids energy waste caused by too high temperature or too long time, making the production process more energy - efficient and reducing the production cost.

[0015] As a further technical solution, the pressure of the forming is 10 - 15 MPa.

[0016] As a further technical solution, the impregnation is carried out in two steps, and the viscosities of the impregnants used in the two impregnations are different.

[0017] In the present invention, impregnating in two steps and using impregnants with different viscosities can better adapt to the complex internal structure and pore distribution of the graphite crucible. The step-by-step impregnation method can more effectively penetrate the impregnants into each part, ensuring that each part can be fully impregnated, and can more comprehensively and deeply fill the pore structure inside the crucible, reduce the porosity, and improve the quality and performance of the crucible.

[0018] As a further technical solution, the impregnation includes the following steps: adding a first impregnating agent to the semi-finished product, introducing nitrogen, and obtaining a first impregnated blank after the first pressure curing; adding a second impregnating agent to the first impregnated blank, introducing nitrogen, and obtaining a second impregnated blank after the second pressure curing.

[0019] As a further technical solution, the impregnation includes the following steps: adding a first impregnating agent to the semi-finished product, introducing nitrogen, taking it out after the first pressure holding, and obtaining a first impregnated blank after the first curing; adding a second impregnating agent to the first impregnated blank, introducing nitrogen, taking it out after the second pressure holding, and obtaining a second impregnated blank after the second curing.

[0020] In the present invention, after adding the impregnating agent, nitrogen is introduced and pressure is held. Nitrogen can expel the air in the pores of the crucible semi-finished product, forming a relatively vacuum environment, which is beneficial for the impregnating agent to enter the pores more smoothly. At the same time, the operation of holding pressure can increase the penetration driving force of the impregnating agent, enabling the impregnating agent to fill more deeply and fully into the fine pores and complex structures of the crucible, improving the uniformity and density of impregnation, and reducing the porosity of the crucible.

[0021] As a further technical solution, the addition amount of the first impregnating agent should satisfy that the liquid level of the first impregnating agent is 10 mm higher than the top end of the semi-finished product; the addition amount of the second impregnating agent should satisfy that the liquid level of the second impregnating agent is 10 mm higher than the top end of the first impregnated blank.

[0022] As a further technical solution, the pressure of the first pressure application and the pressure of the second pressure application are both 1 MPa, and the time of holding pressure is both 4 h.

[0023] As a further technical solution, the pressure of the first curing is 1.1 MPa, the temperature is 140 °C, the heating rate is 5 °C / h, the time is 5 h, and the gas atmosphere is nitrogen; the pressure of the second curing is 1.1 MPa, the temperature is 140 °C, the heating rate is 5 °C / h, the time is 4 h, and the gas atmosphere is nitrogen.

[0024] As a further technical solution, the first impregnating agent is a thermosetting phenolic resin with a viscosity of 15 - 30 s and a model number of 2124, and the second impregnating agent is a thermosetting phenolic resin with a viscosity of 120 - 250 s and a model number of 2127.

[0025] In the present invention, a method of two - time impregnation using two thermosetting phenolic resins with different viscosities and model numbers as impregnating agents is adopted. For the first time, a thermosetting phenolic resin with a viscosity of 15 - 30 s and a model number of 2124 is used as the first impregnating agent. Its lower viscosity enables the impregnating agent to quickly and fully penetrate into the tiny pores and internal structures of the semi - finished product, effectively filling the pores and laying a foundation for subsequent impregnation and improvement of the overall performance of the crucible. For the second time, a thermosetting phenolic resin with a viscosity of 120 - 250 s and a model number of 2127 is used as the second impregnating agent to further fill and seal the remaining tiny pores, significantly improving the density and strength of the crucible. Through this two - time impregnation process of first impregnating large pores with low - viscosity resin and then impregnating small pores with high - viscosity resin, the internal structure of the high - strength graphite crucible becomes more uniform and dense, effectively reducing the internal defects and porosity of the graphite crucible.

[0026] As a further technical solution, the temperatures of the first impregnating agent and the second impregnating agent are 60 - 70 °C, for example, they can be 60 °C, 62 °C, 64 °C, 66 °C, 68 °C, 70 °C, and the preferred temperature is 70 °C.

[0027] As a further technical solution, the temperature of the roasting is 950 - 1200 °C and the time is 30 d.

[0028] As a further technical solution, the temperature of the graphitization is 2300 - 3000 °C.

[0029] The working principle and beneficial effects of the present invention are as follows: 1. In the present invention, graphitized coke, medium - temperature pitch, and modified pitch are used as raw materials. The graphitized coke provides the basic framework of the crucible and good high - temperature resistance, ensuring the stability of the crucible in a high - temperature use environment. The medium - temperature pitch and modified pitch, as binders, can tightly bond the graphitized coke particles together to form a solid overall structure, thereby effectively improving the strength of the crucible.

[0030] 2. In the present invention, the modified pitch is composed of a first modified pitch and a second modified pitch with different penetration degrees. The modified pitches with different penetration degrees have different performance characteristics. When they cooperate with each other, they can better fill the gaps between graphitized coke particles during the bonding process, forming a more uniform and denser internal structure. The reason is that the first modified pitch with a smaller penetration degree has a relatively higher hardness and is not easy to flow at high temperatures, which can provide a strong initial bonding force. While the second modified pitch with a larger penetration degree is relatively soft and has better fluidity, which can better penetrate into the tiny gaps between graphitized coke particles during the crucible forming process, filling these gaps, thereby further enhancing the bonding force between particles, making the entire graphite crucible structure more dense, and effectively improving the strength of the graphite crucible. Detailed Embodiment

[0031] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0032] In the following examples and comparative examples: Graphitized coke: Purchased from Shanghai Youai Metallurgical Materials Co., Ltd. Medium-temperature pitch: Softening point 80 - 90 °C, purchased from Hebei Hankai Energy Technology Development Co., Ltd. First modified pitch: Penetration degree 45 mm, purchased from Hebei Liujun Trading Co., Ltd. Second modified pitch: Penetration degree 90 mm, purchased from Hebei Liujun Trading Co., Ltd.

[0033] Example 1 A high-strength graphite crucible comprises the following raw material components in parts by weight: 70 parts of graphitized coke, 15 parts of medium-temperature pitch, and 5 parts of modified pitch; wherein the grading particle sizes of the graphitized coke are 0 - 2 mm, 2 - 5 mm, and 5 - 8 mm, and the mass ratio of each particle size level is 18:1:1. The modified pitch is composed of a first modified pitch and a second modified pitch with a mass ratio of 3:1. A preparation method of a high-strength graphite crucible includes the following steps: After proportioning graphitized coke, add medium-temperature pitch and modified pitch, knead at 150 °C for 70 min. After cooling the material, form it under a pressure of 12 MPa to obtain a semi-finished product. Add phenolic resin 2124 at 70 °C to the semi-finished product, and the addition amount should satisfy that the liquid level of phenolic resin 2124 is 10 mm higher than the top of the semi-finished product. Introduce nitrogen, pressurize to 1 MPa, keep the pressure constant for 4 h and then take it out. Under a nitrogen atmosphere, heat it at a heating rate of 5 °C / h to 140 °C, with a pressure of 1.1 MPa, cure for 4 h, roast at 950 °C for 30 d and then graphitize at 2300 °C to obtain the graphite crucible.

[0034] Example 2 A high-strength graphite crucible includes the following raw materials by weight: 75 parts of graphitized coke, 18 parts of medium-temperature pitch, and 8 parts of modified pitch; among them, the grading particle sizes of the graphitized coke are 0 - 2 mm, 2 - 5 mm, and 5 - 8 mm, and the mass ratio of each particle size level is 18:1:1. The modified pitch is composed of a first modified pitch and a second modified pitch with a mass ratio of 3:1. A preparation method of a high-strength graphite crucible includes the following steps: After proportioning graphitized coke, add medium-temperature pitch and modified pitch, knead at 150 °C for 70 min. After cooling the material, form it under a pressure of 10 MPa to obtain a semi-finished product. Add phenolic resin 2124 at 70 °C to the semi-finished product, and the addition amount should satisfy that the liquid level of phenolic resin 2124 is 10 mm higher than the top of the semi-finished product. Introduce nitrogen, pressurize to 1 MPa, keep the pressure constant for 4 h and then take it out. Under a nitrogen atmosphere, heat it at a heating rate of 5 °C / h to 140 °C, with a pressure of 1.1 MPa, cure for 4 h, roast at 1100 °C for 30 d and then graphitize at 2600 °C to obtain the graphite crucible.

[0035] Example 3 A high-strength graphite crucible includes the following raw materials by weight: 80 parts of graphitized coke, 20 parts of medium-temperature pitch, and 10 parts of modified pitch; among them, the grading particle sizes of the graphitized coke are 0 - 2 mm, 2 - 5 mm, and 5 - 8 mm, and the mass ratio of each particle size level is 18:1:1. The modified pitch is composed of a first modified pitch and a second modified pitch with a mass ratio of 3:1. A preparation method of a high-strength graphite crucible includes the following steps: After proportioning graphitized coke, add medium-temperature pitch and modified pitch, knead at 150 °C for 70 min. After cooling the material, form it under a pressure of 15 MPa to obtain a semi-finished product. Add phenolic resin 2124 at 70 °C to the semi-finished product, and the addition amount should satisfy that the liquid level of phenolic resin 2124 is 10 mm higher than the top of the semi-finished product. Introduce nitrogen, pressurize to 1 MPa, keep the pressure constant for 5 h and then take it out. Under a nitrogen atmosphere, heat it at a heating rate of 5 °C / h to 140 °C, with a pressure of 1.1 MPa, cure for 4 h, roast at 1200 °C for 30 d and then graphitize at 3000 °C to obtain the graphite crucible.

[0036] Example 4 Compared with Example 1, the difference in Example 4 is that the modified pitch is composed of a first modified pitch and a second modified pitch with a mass ratio of 4:1.

[0037] Example 5 Compared with Example 4, the difference in Example 5 is that the mass ratio of each particle size level of graphitized coke is 17:1:1.

[0038] Example 6 Compared with Example 4, the difference in Example 6 is that the mass ratio of each particle size level of graphitized coke is 19:1:1.

[0039] Example 7 Compared with Example 4, the difference in Example 7 is that the graded particle size of graphitized coke is 0 - 2 mm and 2 - 5 mm, and the mass ratio of each particle size level is 18:1.

[0040] Example 8 Compared with Example 4, the difference in Example 8 is that the particle size of graphitized coke is only 0 - 2 mm.

[0041] Example 9 Compared with Example 4, the difference in Example 9 is that phenolic resin 2124 is replaced by phenolic resin 2127.

[0042] Example 10 A high-strength graphite crucible, comprising the following raw materials in parts by weight: 70 parts of graphitized coke, 15 parts of medium-temperature pitch, and 5 parts of modified pitch; wherein the graded particle size of graphitized coke is 0 - 2 mm, 2 - 5 mm, and 5 - 8 mm, and the mass ratio of each particle size level is 18:1:1, and the modified pitch is composed of a first modified pitch and a second modified pitch with a mass ratio of 4:1; A preparation method of a high-strength graphite crucible includes the following steps: After proportioning graphitized coke, add medium-temperature pitch and modified pitch, knead at 150 °C for 70 min. After cooling the material, form it under a pressure of 12 MPa to obtain a semi-finished product. Add phenolic resin 2127 at 70 °C to the semi-finished product, and the addition amount should satisfy that the liquid level of phenolic resin 2127 is 10 mm higher than the top of the semi-finished product. Introduce nitrogen, pressurize to 1 MPa, keep the pressure constant for 4 h and then take it out. Under a nitrogen atmosphere, heat it at a heating rate of 5 °C / h to 140 °C, with a pressure of 1.1 MPa, and cure for 5 h to obtain the first impregnated blank. Add phenolic resin 2124 at 70 °C to the first impregnated blank, and the addition amount should satisfy that the liquid level of phenolic resin 2124 is 10 mm higher than the top of the first impregnated blank. Introduce nitrogen, pressurize to 1 MPa, keep the pressure constant for 4 h and then take it out. Under a nitrogen atmosphere, heat it at a heating rate of 5 °C / h to 140 °C, with a pressure of 1.1 MPa, and cure for 4 h to obtain the second impregnated blank. Roast at 950 °C for 30 d and then graphitize at 2300 °C to obtain the graphite crucible.

[0043] Example 11 A high-strength graphite crucible includes the following raw materials in parts by weight: 70 parts of graphitized coke, 15 parts of medium-temperature pitch, and 5 parts of modified pitch; among them, the graded particle sizes of the graphitized coke are 0 - 2 mm, 2 - 5 mm, and 5 - 8 mm, and the mass ratio of each particle size is 18:1:1. The modified pitch is composed of a first modified pitch and a second modified pitch with a mass ratio of 4:1; A preparation method of a high-strength graphite crucible includes the following steps: After proportioning graphitized coke, add medium-temperature pitch and modified pitch, knead at 150 °C for 70 min. After cooling the material, form it under a pressure of 12 MPa to obtain a semi-finished product. Add phenolic resin 2124 at 70 °C to the semi-finished product, and the addition amount should satisfy that the liquid level of phenolic resin 2124 is 10 mm higher than the top of the semi-finished product. Introduce nitrogen, pressurize to 1 MPa, keep the pressure constant for 4 h and then take it out. Under a nitrogen atmosphere, heat it at a heating rate of 5 °C / h to 140 °C, with a pressure of 1.1 MPa, and cure for 4 h to obtain the first impregnated blank. Add phenolic resin 2127 at 70 °C to the first impregnated blank, and the addition amount should satisfy that the liquid level of phenolic resin 2127 is 10 mm higher than the top of the first impregnated blank. Introduce nitrogen, pressurize to 1 MPa, keep the pressure constant for 4 h and then take it out. Under a nitrogen atmosphere, heat it at a heating rate of 5 °C / h to 140 °C, with a pressure of 1.1 MPa, and cure for 5 h to obtain the second impregnated blank. Roast at 950 °C for 30 d and then graphitize at 2300 °C to obtain the graphite crucible.

[0044] Example 12 A high-strength graphite crucible, comprising the following raw materials in parts by weight: 70 parts of graphitized coke, 15 parts of medium-temperature pitch, and 5 parts of modified pitch; wherein the graded particle sizes of the graphitized coke are 0-2 mm, 2-5 mm, and 5-8 mm, and the mass ratio of each particle size is 18:1:1. The modified pitch is composed of a first modified pitch and a second modified pitch with a mass ratio of 4:1; A preparation method of a high-strength graphite crucible, comprising the following steps: after proportioning the graphitized coke, adding medium-temperature pitch and modified pitch, kneading at 150 °C for 70 min. After cooling the material, forming at a pressure of 12 MPa to obtain a semi-finished product. Add phenolic resin 2127 at 70 °C to the semi-finished product, and the addition amount should satisfy that the liquid level of phenolic resin 2127 is 10 mm higher than the top of the semi-finished product. Introduce nitrogen, pressurize to 1 MPa, keep the pressure constant for 4 h and then take out. In a nitrogen atmosphere, heat up at a heating rate of 5 °C / h to 140 °C, with a pressure of 1.1 MPa, and cure for 5 h to obtain the first impregnated blank. Add phenolic resin 2127 at 70 °C to the first impregnated blank, and the addition amount should satisfy that the liquid level of phenolic resin 2127 is 10 mm higher than the top of the first impregnated blank. Introduce nitrogen, pressurize to 1 MPa, keep the pressure constant for 4 h and then take out. In a nitrogen atmosphere, heat up at a heating rate of 5 °C / h to 140 °C, with a pressure of 1.1 MPa, and cure for 5 h to obtain the second impregnated blank. Roast at 950 °C for 30 d and then graphitize at 2300 °C to obtain the graphite crucible.

[0045] Example 13 A high-strength graphite crucible, comprising the following raw materials in parts by weight: 70 parts of graphitized coke, 15 parts of medium-temperature pitch, and 5 parts of modified pitch; wherein the graded particle sizes of the graphitized coke are 0-2 mm, 2-5 mm, and 5-8 mm, and the mass ratio of each particle size is 18:1:1. The modified pitch is composed of a first modified pitch and a second modified pitch with a mass ratio of 4:1; A preparation method of a high-strength graphite crucible, comprising the following steps: after proportioning graphitized coke, adding medium-temperature pitch and modified pitch, kneading at 150 °C for 70 min, after cooling the material, forming under a pressure of 12 MPa to obtain a semi-finished product, adding phenolic resin 2124 at 70 °C to the semi-finished product, and the addition amount should satisfy that the liquid level of phenolic resin 2124 is 10 mm higher than the top of the semi-finished product, introducing nitrogen, pressurizing to 1 MPa, taking out after maintaining the pressure for 4 h, under a nitrogen atmosphere, heating at a heating rate of 5 °C / h to 140 °C, with a pressure of 1.1 MPa, curing for 4 h to obtain a first impregnated blank, adding phenolic resin 2124 at 70 °C to the first impregnated blank, and the addition amount should satisfy that the liquid level of phenolic resin 2124 is 10 mm higher than the top of the first impregnated blank, introducing nitrogen, pressurizing to 1 MPa, taking out after maintaining the pressure for 4 h, under a nitrogen atmosphere, heating at a heating rate of 5 °C / h to 140 °C, with a pressure of 1.1 MPa, curing for 4 h to obtain a second impregnated blank, roasting at 950 °C for 30 d and then graphitizing at 2300 °C to obtain the graphite crucible.

[0046] Comparative Example 1 Compared with Example 1, the difference in Comparative Example 1 is that the modified pitch is only the first modified pitch.

[0047] Comparative Example 2 Compared with Example 1, the difference in Comparative Example 2 is that the modified pitch is only the second modified pitch.

[0048] Comparative Example 3 Compared with Example 1, the difference in Comparative Example 3 is that no modified pitch is added.

[0049] Experimental Example 1 For the graphite crucibles prepared in Examples 1 to 8 and Comparative Examples 1 to 3, according to the test method specified in GB / T 13465.3-2014 "Test Methods for Impervious Graphite Materials - Part 3: Compressive Strength", the compressive strength of the samples was tested, and the sample size was Ф45 mm × 45 mm.

[0050] The test results are shown in Table 1: Table 1 Performance test results of the graphite crucibles prepared in Examples 1 to 8 and Comparative Examples 1 to 3

[0051] As can be seen from Table 1, when the modified pitch is composed of the first modified pitch and the second modified pitch, the strength of the graphite crucible can be improved.

[0052] Experimental Example 2 The apparent porosity of the graphite crucibles prepared in Example 4 and Examples 9 to 13 was tested according to the test method specified in GB / T 2997-2015 "Test Methods for Bulk Density, Apparent Porosity and True Porosity of Dense Shaped Refractory Products".

[0053] The test results are shown in Table 2 as follows: Table 2 Performance test results of the graphite crucibles prepared in Example 4 and Examples 9 to 13

[0054] As can be seen from Table 2, when the impregnation is carried out in two steps and the viscosity of the first impregnating agent is less than that of the second impregnating agent, the apparent porosity of the graphite crucible can be reduced.

[0055] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A high-strength graphite crucible, characterized in that, It comprises the following raw materials in parts by weight: 70 - 80 parts of graphitized coke, 15 - 20 parts of medium-temperature pitch, and 5 - 10 parts of modified pitch, wherein the modified pitch is composed of first modified pitch and second modified pitch, and the penetration degrees of the first modified pitch and the second modified pitch are different.

2. A high-strength graphite crucible according to claim 1, characterized in that, The penetration degree of the first modified pitch is 45 mm, the penetration degree of the second modified pitch is 90 mm, and the mass ratio of the first modified pitch to the second modified pitch is 3 - 4:

1.

3. A high-strength graphite crucible according to claim 1, characterized in that, The grading method of the graphitized coke is three-stage continuous grading, and the three-stage continuous grading includes 0 - 2 mm, 2 - 5 mm, and 5 - 8 mm, and the mass ratio of each stage is 17 - 19:1:

1.

4. A preparation method of a high-strength graphite crucible, which is used to prepare a high-strength graphite crucible as described in any one of claims 1 to 3, and is characterized in that, It includes the following steps: Adding the graphitized coke into the medium-temperature pitch and the modified pitch for kneading, obtaining a semi-finished product through cooling and shaping, and then obtaining a graphite crucible after impregnation, roasting, and graphitization of the semi-finished product.

5. The preparation method of a high-strength graphite crucible according to claim 4, wherein, The temperature of the kneading is 145 - 150 °C, and the time of the kneading is 70 - 80 min.

6. The preparation method of a high-strength graphite crucible according to claim 4, characterized in that, The pressure of the shaping is 10 - 15 MPa.

7. The preparation method of a high-strength graphite crucible according to claim 4, characterized in that, The impregnation is carried out in two times, and the viscosities of the impregnants used in the two impregnations are different.

8. The preparation method of a high-strength graphite crucible according to claim 7, characterized in that, The impregnation includes the following steps: adding a first impregnating agent to the semi-finished product, introducing nitrogen, obtaining a first impregnated blank after the first pressure curing, adding a second impregnating agent to the first impregnated blank, introducing nitrogen, and obtaining a second impregnated blank after the second pressure curing.

9. The preparation method of a high-strength graphite crucible according to claim 8, wherein, The first impregnating agent is a thermosetting phenolic resin with a viscosity of 15 - 30 s and a model number of 2124, and the second impregnating agent is a thermosetting phenolic resin with a viscosity of 120 - 250 s and a model number of 2127.

10. The preparation method of a high-strength graphite crucible according to claim 4, characterized in that, The temperature of the roasting is 950 - 1200 °C, and the time is 30 d.

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