Carbon-carbon composite sagger and preparation method and application thereof

Abstract

The invention belongs to the technical field of sagger preparation, and particularly relates to a carbon-carbon composite sagger and a preparation method and application thereof. The carbon-carbon composite sagger provided by the invention is prepared by the following steps: 1) alternately laying and needling a carbon fiber web coated with a water-based carburant and carbon fiber plain cloth to obtain a preform; the water-based carburant comprises water, carbon material particles and coal tar pitch powder; and 2) impregnating the preform obtained in the step 1) in resin for compression molding, and then carbonizing and thermally depositing a carbon coating to obtain the carbon-carbon composite sagger. The sagger is simple in overall preparation process, high in operability, low in production cost and high in manufacturing efficiency, and the prepared carbon-carbon composite sagger is high in bending strength and long in service life.

Description

Technical Field

[0001] The invention belongs to the technical field of sagger preparation, and in particular relates to a carbon-carbon composite sagger and a preparation method and application thereof. Background Art

[0002] Sagger is a new type of special tooling for preparing raw materials such as ternary lithium in the lithium battery industry. Traditional industry saggers are mainly made of inorganic non-metallic materials or graphite materials, which are pressed and baked. The main disadvantage is that the mechanical properties of the materials are poor (low bending strength), and they are prone to wear, collision damage, cracking, etc., which shortens the service life of the sagger.

[0003] The new continuous fiber preform carbon-carbon sagger has the advantages of good sealing and high mechanical properties. It can not only effectively solve the problem of its short service life, but also slow down the corrosion rate of the crucible by corrosive metal to a certain extent, thereby effectively reducing its life cycle cost. Moreover, the thickness can be thinner than that of graphite sagger, which increases its negative electrode raw material loading capacity and develops rapidly.

[0004] However, the existing continuous fiber preform carbon-carbon sagger has limited improvement in bending strength and service life, and the preform process adopts a method of reserving dimensions for later machining, resulting in low raw material utilization and complex preparation process (preform preparation, chemical vapor infiltration CVI, impregnation carbonization PIP, high-temperature graphitization, machining, coating), resulting in a long manufacturing cycle and high production cost. Summary of the invention

[0005] Therefore, the technical problem to be solved by the present invention is to overcome the defects of the carbon-carbon sagger prepared by the prior art, such as limited improvement in bending strength and service life, complex process, long manufacturing cycle and high production cost, so as to provide a carbon-carbon composite sagger and its preparation method and application.

[0006] The present invention provides a method for preparing a carbon-carbon composite sagger, comprising the following steps:

[0007] 1) alternately layering a carbon fiber web coated with a water-based recarburizer and a carbon fiber plain cloth, and needle punching to obtain a preform;

[0008] The water-based recarburizer comprises water, carbon material particles and coal tar pitch powder;

[0009] 2) The preform obtained in step 1) is immersed in resin for compression molding, and then carbonized and thermally deposited with a carbon coating to obtain the carbon-carbon composite sagger.

[0010] The present invention does not need to specifically limit the number of layers of the carbon fiber mesh coated with water-based carburizer and the carbon fiber plain cloth alternately laid, and it can be specifically adjusted according to the thickness of the final required sagger, and the thickness of the carbon fiber mesh coated with water-based carburizer and the carbon fiber plain cloth alternately laid can reach the preset thickness of the sagger, and the optional carbon fiber mesh coated with water-based carburizer and the carbon fiber plain cloth alternately laid once is a layer, it can be understood that first a carbon fiber mesh coated with water-based carburizer is laid, and then a carbon fiber plain cloth is laid, which is an alternate layer once, which is a layer; first a carbon fiber mesh coated with water-based carburizer is laid, and then a carbon fiber plain cloth is laid, and then a carbon fiber mesh coated with water-based carburizer is laid, and then a carbon fiber plain cloth is laid twice, which is two layers; optionally, the carbon fiber mesh coated with water-based carburizer and the carbon fiber plain cloth are alternately laid to obtain 7-10 layers.

[0011] Preferably, the acupuncture depth in step 1) is 12-16 mm, and the acupuncture step size is 4.5-8 mm / needle.

[0012] Optionally, the needle spacing in the acupuncture step in step 1) is 6-8 mm; further optionally, the needle spacing in the acupuncture step is 8 mm.

[0013] Preferably, the mass ratio of the carbon material particles to the coal tar pitch powder in step 1) is 1:(0.1-0.3);

[0014] The mass ratio of the total mass of the carbon material particles and the coal tar pitch powder to water is 1:(1-1.5);

[0015] The mass ratio of the total mass of the carbon fiber mesh and the carbon fiber plain cloth to the water-based recarburizer is 1.6:(0.8-1).

[0016] Preferably, the carbon material particles in step 1) are selected from graphite powder.

[0017] Preferably, the resin in step 2) is selected from at least one of phenolic resin, furan resin and epoxy resin;

[0018] The mass ratio of the resin to the preform is (0.8-1):0.8;

[0019] The compression molding temperature is 80-250° C., the compression molding pressure is 3-60 MPa, and the compression molding time is 2-2.5 h.

[0020] Preferably, the carbonization temperature is 800-1100° C., and the carbonization time is 40-50 h.

[0021] Preferably, the thermal deposition temperature in step 2) is 900-1100° C., the thermal deposition time is 10-300 h, and the pyrolysis gas during thermal deposition is an organic carbon source gas;

[0022] The organic carbon source gas is selected from at least one of methane and propane;

[0023] Preferably, the organic carbon source gas is methane.

[0024] The present invention provides a carbon-carbon composite sagger, which is prepared by the method for preparing the carbon-carbon composite sagger.

[0025] The present invention provides an application of the carbon-carbon composite sagger described above in the preparation of battery materials.

[0026] The technical solution of the present invention has the following advantages:

[0027] (1) The preparation method of the carbon-carbon composite sagger provided by the present invention comprises the following steps: 1) alternately layering a carbon fiber mesh coated with a water-based recarburizer and a carbon fiber plain cloth, and needle punching to obtain a preform; the water-based recarburizer comprises water, carbon material particles, and coal tar pitch powder; 2) immersing the preform obtained in step 1) in a resin, compression molding, and then carbonizing and thermally depositing a carbon coating to obtain the carbon-carbon composite sagger. The present invention alternately layers a carbon fiber mesh coated with a specific water-based carburizer and a carbon fiber plain cloth, and uses a specific needling step to perform needling treatment, which can quickly increase density, reduce subsequent densification processes, and improve the mechanical properties of the sagger. At the same time, it can slow down the corrosion rate of the sagger by corrosive metals to a certain extent, reduce the destructive force of the roasting environment on the sagger body and surface, and improve the service life of the sagger; and the present invention prepares a preform through a specific preparation process, and introduces a carburizing phase, which can achieve near-net forming, reduce subsequent densification processes and machining processes, impregnation carbonization, high-temperature graphitization and other processes; the overall preparation process of the sagger of the present invention is simple, highly operable, low in production cost, and high in production efficiency, and the prepared carbon-carbon composite sagger has high bending strength and a long service life.

[0028] (2) In the method for preparing the carbon-carbon composite sagger provided by the present invention, the needling depth in step 1) is 12-16 mm, and the needling step amount is 4.8-8 mm / needle. The present invention further improves the bending strength and service life of the carbon-carbon composite sagger by selecting a specific needling step amount.

[0029] (3) In the method for preparing the carbon-carbon composite sagger provided by the present invention, the resin in step 2) is selected from at least one of phenolic resin, furan resin, and epoxy resin; the above-mentioned specific resin is selected, which has low volatility during the curing process, less pores caused by residual gas inside the sagger, or a high residual carbon rate, can achieve a densification effect, so that the bending strength and service life of the prepared carbon-carbon composite sagger are further improved.

[0030] (4) The method for preparing the carbon-carbon composite sagger provided by the present invention can control the size and shape of the product by using different molds, and different molds can also be selected according to actual needs. DETAILED DESCRIPTION

[0031] The following examples are provided for a better understanding of the present invention, but are not intended to limit the best mode of implementation, nor to limit the content and protection scope of the present invention. Any product identical or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior arts shall fall within the protection scope of the present invention.

[0032] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in the field can be used. If no manufacturer is specified for the reagents or instruments used, they are all conventional reagent products that can be obtained commercially.

[0033] Example 1

[0034] This embodiment provides a method for preparing a carbon-carbon composite sagger, comprising the following steps:

[0035] 1) 8 layers of carbon fiber mesh coated with water-based carburizer and carbon fiber plain cloth are alternately laid (one layer is one layer), the total mass ratio of the carbon fiber mesh and the carbon fiber plain cloth to the mass ratio of the water-based carburizer is 1.6:0.9, and then acupuncture is performed, the needle spacing of the acupuncture is 8 mm, the acupuncture depth is 14 mm, and the acupuncture step amount is 8 mm / needle, to obtain a preform;

[0036] The water-based recarburizer comprises water, graphite powder and coal tar pitch powder; the mass ratio of the graphite powder to the coal tar pitch powder is 1:0.2; the mass ratio of the total mass of the graphite powder and the coal tar pitch powder to water is 1:1.3;

[0037] 2) The preform obtained in step 1) is immersed in phenolic resin and molded with a mold, the mass ratio of the resin to the preform is 0.9:0.8, the molding temperature is 150°C, the molding pressure is 40MPa, the molding time is 2.3h, and then carbonized at 950°C for 45h, and then thermally deposited with a carbon coating, the pyrolysis gas during thermal deposition is methane gas, the thermal deposition temperature is 1000°C, and the thermal deposition time is 150h, to obtain the carbon-carbon composite sagger.

[0038] Example 2

[0039] This embodiment provides a method for preparing a carbon-carbon composite sagger, comprising the following steps:

[0040] 1) 8 layers of carbon fiber mesh coated with water-based carburizer and carbon fiber plain cloth are alternately laid (one layer is one layer), the total mass ratio of the carbon fiber mesh and the carbon fiber plain cloth to the mass ratio of the water-based carburizer is 1.6:1, and then acupuncture is performed, the needle spacing of the acupuncture is 8 mm, the acupuncture depth is 12 mm, and the acupuncture step amount is 7 mm / needle, to obtain a preform;

[0041] The water-based recarburizer comprises water, graphite powder and coal tar pitch powder; the mass ratio of the graphite powder to the coal tar pitch powder is 1:0.1; the mass ratio of the total mass of the graphite powder and the coal tar pitch powder to water is 1:1;

[0042] 2) The preform obtained in step 1) is immersed in a phenolic resin and compression molded with a mold, wherein the mass ratio of the resin to the preform is 0.8:0.8, the compression molding temperature is 80°C, the compression molding pressure is 3MPa, and the compression molding time is 2.5h, and then carbonized at 800°C for 40h, and then thermally deposited with a carbon coating, the pyrolysis gas during thermal deposition is methane gas, the thermal deposition temperature is 900°C, and the thermal deposition time is 300h, to obtain the carbon-carbon composite sagger.

[0043] Example 3

[0044] This embodiment provides a method for preparing a carbon-carbon composite sagger, comprising the following steps:

[0045] 1) 8 layers of carbon fiber mesh coated with water-based carburizer and carbon fiber plain cloth are alternately laid (one layer is one layer), the total mass ratio of the carbon fiber mesh and the carbon fiber plain cloth to the mass ratio of the water-based carburizer is 1.6:0.8, and then acupuncture is performed, the needle spacing of the acupuncture is 8 mm, the acupuncture depth is 16 mm, and the acupuncture step amount is 4.5 mm / needle, to obtain a preform;

[0046] The water-based recarburizer comprises water, graphite powder and coal tar pitch powder; the mass ratio of the graphite powder to the coal tar pitch powder is 1:0.3; the mass ratio of the total mass of the graphite powder and the coal tar pitch powder to water is 1:1.5;

[0047] 2) The preform obtained in step 1) is immersed in phenolic resin and molded with a mold, the mass ratio of the resin to the preform is 1:0.8, the molding temperature is 250°C, the molding pressure is 60MPa, the molding time is 2h, and then carbonized at 1100°C for 50h, and then thermally deposited with a carbon coating, the pyrolysis gas during thermal deposition is methane gas, the thermal deposition temperature is 1100°C, and the thermal deposition time is 10h, to obtain the carbon-carbon composite sagger.

[0048] Example 4

[0049] This embodiment provides a method for preparing a carbon-carbon composite sagger, which is different from Embodiment 1 only in that the needle penetration step amount in step 1) is 3.5 mm / needle.

[0050] Comparative Example 1

[0051] This comparative example provides a method for preparing a sagger, which differs from Example 1 in that in step 1), 8 layers of carbon fiber mesh and carbon fiber plain cloth are alternately laid (one layer is one layer of alternating carbon fiber mesh and carbon fiber plain cloth), and then acupuncture is performed, the needle spacing of the acupuncture is 8 mm, the acupuncture depth is 14 mm, and the acupuncture step amount is 8 mm / needle to obtain a preform.

[0052] Comparative Example 2

[0053] This comparative example provides a method for preparing a sagger, which is different from Example 1 in that in step 1), 8 layers of carbon fiber mesh and carbon fiber plain cloth coated with a water-based carburizer are alternately laid (one layer is one layer of carbon fiber mesh and carbon fiber plain cloth), the total mass ratio of the carbon fiber mesh and carbon fiber plain cloth to the mass ratio of the water-based carburizer is 1.6:0.9, and then acupuncture is performed, the needle spacing of the acupuncture is 8 mm, the acupuncture depth is 14 mm, and the acupuncture step amount is 8 mm / needle, to obtain a preform;

[0054] The water-based recarburizer includes water, graphite powder and coal tar pitch powder; the mass ratio of the graphite powder to the coal tar pitch powder is 1:0.2; the mass ratio of the total mass of the graphite powder and the coal tar pitch powder to water is 1:1.3.

[0055] Comparative Example 3

[0056] This comparative example provides a method for preparing a sagger, comprising the following steps:

[0057] A mixture of graphite powder, silicon carbide powder, phenolic resin powder and chopped carbon fiber (length 7-10 mm) in a mass ratio of 5:1:1:2 is then molded using a mold, the molding temperature is 150°C, the molding pressure is 40MPa, the molding time is 2.3h, and then carbonized at 950°C for 45h, and then a carbon coating is thermally deposited, the pyrolysis gas during thermal deposition is methane gas, the thermal deposition temperature is 1000°C, and the thermal deposition time is 150h, to obtain the sagger.

[0058] Test Case

[0059] The saggers of Examples 1-4 and Comparative Examples 1-3 of the present invention were subjected to a bending strength test, and the test method was based on the standard GB / T 1449-2005.

[0060] The service life of the saggers of Examples 1-4 of the present invention and Comparative Examples 1-3 was tested. The test method was to keep the temperature at 900°C for 200 hours in an inert gas atmosphere, and observe the surface state after the insulation. The appearance of cracks on the surface indicates that the service life is short. The evaluation criteria for cracks: more than 3 fine cracks less than 1 mm appear on the surface of the sagger, or at least 1 crack with a width of more than 1 mm; the evaluation criteria for microcracks: 1-2 fine cracks less than 1 mm appear on the surface of the sagger; the evaluation criteria for a good surface: no cracks on the surface of the sagger. The test results are shown in Table 1.

[0061] Table 1

[0062] Bending strength / MPa Surface state Example 1 80 Good surface Example 2 75 Good surface Example 3 70 Good surface Example 4 60 Micro cracks appear Comparative Example 1 55 Cracks appear Comparative Example 2 55 Cracks appear Comparative Example 3 30 Cracks appear

[0063] As can be seen from Table 1, the bending strength of Examples 1-3 is significantly higher than that of Comparative Examples 1-3, and the surface of Examples 1-3 is good without cracks, indicating that the carbon-carbon sagger prepared by the present invention has good mechanical properties and a long service life. In fact, in the actual production process of the factory, the service life of the saggers of Example 1 and Comparative Example 3 under the same working environment is indeed different, which is consistent with the trend of the experimental results of 900°C insulation for 200h under an inert gas atmosphere. The actual service life of the sagger of Example 1 is 6 months, while the actual service life of the sagger of Comparative Example 3 is 3 months. The bending strength of Example 4 is significantly lower than that of other embodiments, and the surface crack situation is slightly worse than that of Examples 1-3, indicating that further limiting the stepping amount of acupuncture can cooperate with the specific process of the present invention to further improve the sagger with good mechanical properties and a long service life.

[0064] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the present invention.

Claims

1. A method for preparing a carbon-carbon composite sagger, characterized in that: The following steps are involved: 1) alternately layering a carbon fiber web coated with a water-based recarburizer and a carbon fiber plain cloth, and needle punching to obtain a preform; The water-based recarburizer comprises water, carbon material particles and coal tar pitch powder; 2) The preform obtained in step 1) is immersed in resin for compression molding, and then carbonized and thermally deposited with a carbon coating to obtain the carbon-carbon composite sagger.

2. The method for preparing the carbon-carbon composite sagger according to claim 1, characterized in that: In step 1), the acupuncture depth is 12-16 mm, and the acupuncture step is 4.5-8 mm / needle.

3. The method for preparing the carbon-carbon composite sagger according to claim 1 or 2, characterized in that: The mass ratio of the carbon material particles to the coal tar pitch powder in step 1) is 1:(0.1-0.3); The mass ratio of the total mass of the carbon material particles and the coal tar pitch powder to water is 1:(1-1.5); The mass ratio of the total mass of the carbon fiber mesh and the carbon fiber plain cloth to the water-based recarburizer is 1.6:(0.8-1).

4. The method for preparing the carbon-carbon composite sagger according to any one of claims 1 to 3, characterized in that: The carbon material particles in step 1) are selected from graphite powder.

5. The method for preparing the carbon-carbon composite sagger according to any one of claims 1 to 4, characterized in that: The resin in step 2) is selected from at least one of phenolic resin, furan resin and epoxy resin; The mass ratio of the resin to the preform is (0.8-1):0.8; The compression molding temperature is 80-250° C., the compression molding pressure is 3-60 MPa, and the compression molding time is 2-2.5 h.

6. The method for preparing the carbon-carbon composite sagger according to any one of claims 1 to 5, characterized in that: The carbonization temperature is 800-1100° C., and the carbonization time is 40-50 hours.

7. The method for preparing the carbon-carbon composite sagger according to any one of claims 1 to 6, characterized in that: In step 2), the thermal deposition temperature is 900-1100° C., the thermal deposition time is 10-300 hours, and the pyrolysis gas during thermal deposition is an organic carbon source gas.

8. The method for preparing the carbon-carbon composite sagger according to claim 7, characterized in that: The organic carbon source gas is selected from at least one of methane and propane; Preferably, the organic carbon source gas is methane.

9. A carbon-carbon composite sagger, characterized in that: The carbon-carbon composite sagger is prepared by the preparation method of any one of claims 1 to 8.

10. Use of the carbon-carbon composite sagger according to claim 9 in the preparation of battery materials.