A method for sealing pores on a graphite surface based on a phase separation resin coating derived carbon

Abstract

The application provides a method for sealing pores of a graphite surface based on phase separation resin coating derived carbon, comprising the following steps: S1. mixing epoxy resin and epoxy soybean oil in proportion, defoaming, adding a curing agent, and uniformly mixing to obtain a pore sealing agent; S2. adding a diluent to the pore sealing agent prepared in step S1, and diluting to obtain a pore sealing solution; S3. coating or spraying the pore sealing solution prepared in step S2 on the surface of a graphite substrate after cleaning and drying for one or more times; S4. curing the graphite substrate obtained in the above step at a gradient temperature to obtain a graphite substrate loaded with resin; and S5. carbonizing the graphite substrate loaded with resin in an inert atmosphere at a high temperature to obtain a pore-sealed graphite material. The carbon formed by coating the resin coating on the surface of the graphite after high-temperature graphitization is used to seal the pores of the graphite surface, has good coating adhesion, and further improves the durability of the graphite sealing and the service life of the graphite product.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of graphite material sealing, in particular to a method for sealing the surface of graphite based on phase separation resin coating derived carbon. BACKGROUND

[0002] Graphite sealing is to form a protective film or coating on the surface of graphite by physical, chemical or electrochemical methods to reduce or eliminate its pores. By controlling or reducing the pores, sealing can optimize the performance of graphite and improve its efficiency in catalysis, adsorption, lubrication, heat management, corrosion prevention, etc. At the same time, sealing treatment can also improve the stability, durability and service life of graphite materials to meet more extensive application requirements.

[0003] Common graphite sealing methods include: chemical vapor deposition (CVD), in which a gas precursor (such as methane) is decomposed at high temperature to deposit a thin film on the surface of graphite, sealing the pores; coating / surface modification, in which materials with sealing ability (such as resin, polymer, oxide, etc.) are coated on the surface of graphite to form a protective layer. Electrochemical sealing, in which an electrochemical method is used in an electrolyte to deposit a metal or non-metal thin film on the surface of graphite to seal the pores. This method is often used for battery electrode materials and can provide sealing effect without damaging the structure of graphite. For application scenarios that require improved chemical stability, high temperature resistance and mechanical strength of graphite, coating resin and sealing by high temperature carbonization is an effective treatment method and is simpler to operate than CVD and other methods, making it easier to apply in practice. SUMMARY

[0004] The technical problem to be solved is to provide a method for sealing the surface of graphite based on phase separation resin coating derived carbon, which uses the carbon formed by the resin coating on the surface of graphite after high temperature graphitization to seal the surface of graphite.

[0005] Technical solution: A method for sealing the surface of graphite based on phase separation resin coating derived carbon, comprising the following steps: S1. Mix epoxy resin and epoxy soybean oil in proportion, defoam, add curing agent, mix uniformly, and obtain a sealing agent;

[0006] S2. Add a diluent to the sealing agent prepared in step S1 to dilute and obtain a sealing solution;

[0007] S3. Apply or spray the sealing solution prepared in step S2 one or more times on the surface of the cleaned and dried graphite substrate;

[0008] S4. Cure the graphite substrate obtained in the above step at a gradient temperature to obtain a graphite substrate loaded with resin;

[0009] S5. The graphite substrate loaded with resin is carbonized at high temperature under inert atmosphere to obtain a sealed graphite material.

[0010] Preferably, the mass ratio of the epoxy resin and the epoxy soybean oil is 5-9.5:0.5-5.

[0011] Preferably, the mass ratio of the epoxy resin and the curing agent is 5.5-7:3-4.5.

[0012] Preferably, the diluent in step S2 is any one or several of ethanol, acetone or butanone, and the mass ratio of the sealing agent to the diluent is 1-2:1-2.

[0013] Preferably, the coating amount of the sealing solution on the surface of the graphite substrate in step S3 is 2-10 mg / cm 2 .

[0014] Preferably, the temperature for gradient curing in step S4 is 75-85℃, 95-105℃ and 115-125℃ respectively for 1h.

[0015] Preferably, the temperature for high-temperature carbonization in step S5 is 1500-2800℃.

[0016] Beneficial effects: The graphite sealing method has the following advantages:

[0017] 1. The phase separation technology is used to form a multi-phase resin in the resin slurry, the epoxy soybean oil and the epoxy resin are used to induce the formation of microspherical droplets of the epoxy resin in the multi-phase resin slurry, and the sealing effect on the surface of the graphite is achieved by forming spherical resin and derived carbon during the subsequent curing and high-temperature carbonization process;

[0018] 2. The microspherical droplets formed based on the phase separation technology and the microspherical resin formed by curing have good adhesion to the surface of the graphite, so that the derived sealing carbon coating has good coating adhesion, thereby improving the durability of the graphite sealing and prolonging the service life of the graphite product;

[0019] 3. The phase separation resin coating in the present application can locally shrink and pyrolyze in each microsphere range during high-temperature pyrolysis, and form a uniform and dense sealing carbon coating under the accumulation of multiple layers of microspheres, avoiding the cracking problem caused by shrinkage during pyrolysis of a single homogeneous epoxy resin, and improving the yield and production efficiency of the product;

[0020] 4. The graphite surface sealing technical solution has simple equipment and process requirements, low process cost and easy operation, and is more environmentally friendly and safe compared to CVD sealing, electrochemical sealing and other technologies, and has a broad application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is an operation flow chart of a graphite surface sealing technology based on phase separation resin coating derived carbon provided by the present application;

[0022] Figure 2 is a scanning electron microscope graph of the graphite surface after sealing of the graphite surface sealing technology based on phase separation resin coating derived carbon obtained in Example 1;

[0023] Figure 3 is a scanning electron microscope graph of the graphite surface after high temperature carbonization of the single homogeneous epoxy resin coating on the graphite surface obtained in Comparative Example 4;

[0024] Figure 4 is a scanning electron microscope graph of the graphite surface after sealing of the graphite surface sealing technology based on phase separation resin coating derived carbon obtained in Example 1(a) and Comparative Example 5(b). DETAILED DESCRIPTION

[0025] The present application will be further described in conjunction with examples below, and the following examples are an explanation of the present application and the present application is not limited to the following examples:

[0026] Example 1

[0027] A method of sealing the graphite surface based on phase separation resin coating derived carbon, comprising the following steps:

[0028] S1. The epoxy resin and epoxy soybean oil are mixed uniformly at a mass ratio of 5:0.5, defoaming is performed, then 651 low molecular polyamide is added, the mass ratio of the epoxy resin and the curing agent is 7:3, and uniform mixing is performed to obtain a sealing agent;

[0029] S2. Ethanol is added to the sealing agent prepared in step S1 to obtain a sealing solution with a concentration of 50wt% after dilution;

[0030] S3. The sealing solution prepared in step S2 is brushed on the surface of the cleaned and dried graphite substrate, the sealing solution is first coated at a coating amount of 2mg / cm 2 , dried at 80℃, and then resin coating is performed again, and the coating amount of each time is 1mg / cm 2 , and the final coating amount is 10mg / cm 2 ;

[0031] S4. The graphite substrate obtained in the above steps is cured at 80-100-120℃ for 1h respectively to obtain a graphite substrate loaded with resin;

[0032] S5. The graphite substrate loaded with resin is subjected to high temperature carbonization at 1500℃ under an inert atmosphere to obtain a sealed graphite material.

[0033] Example 2

[0034] A method for sealing the surface of graphite based on phase separation resin coating derived carbon, comprising the following steps:

[0035] S1. Mix epoxy resin and epoxy soybean oil at a mass ratio of 5:0.5, then add 651 low molecular polyamide after defoaming, mix evenly, get the sealing agent, the mass ratio of epoxy resin and curing agent is 7:3;

[0036] S2. Add ethanol to the sealing agent prepared in step S1 to dilute and obtain a sealing solution with a concentration of 50wt%;

[0037] S3. Apply the sealing solution prepared in step S2 to the surface of the cleaned and dried graphite substrate, first apply the sealing solution at a coating amount of 2mg / cm 2 , dry at 80℃, then apply the resin again, each time the coating amount is 1mg / cm 2 , and the final coating amount is 6mg / cm 2 ;

[0038] S4. Cure the graphite substrate obtained in the above steps at 80-100-120℃ for 1h respectively to obtain a graphite substrate loaded with resin;

[0039] S5. Carbonize the graphite substrate loaded with resin at 1500℃ under inert atmosphere to obtain a sealed graphite material.

[0040] Example 3

[0041] A method for sealing the surface of graphite based on phase separation resin coating derived carbon, comprising the following steps:

[0042] S1. Mix epoxy resin and epoxy soybean oil at a mass ratio of 5:0.5, then add 651 low molecular polyamide after defoaming, mix evenly, get the sealing agent, the mass ratio of epoxy resin and curing agent is 7:3;

[0043] S2. Add ethanol to the sealing agent prepared in step S1 to dilute and obtain a sealing solution with a concentration of 50wt%;

[0044] S3. Apply the sealing solution prepared in step S2 to the surface of the cleaned and dried graphite substrate, the coating amount of the sealing solution is 2mg / cm 2 ;

[0045] S4. Cure the graphite substrate obtained in the above steps at 80-100-120℃ for 1h respectively to obtain a graphite substrate loaded with resin;

[0046] S5. Carbonize the graphite substrate loaded with resin at 1500℃ under inert atmosphere to obtain a sealed graphite material.

[0047] Example 4

[0048] A method for sealing the surface of graphite based on phase separation resin coating derived carbon, comprising the following steps:

[0049] S1. Mix epoxy resin and epoxy soybean oil uniformly at a mass ratio of 9.5:5, then add 651 low molecular polyamide after defoaming, the mass ratio of epoxy resin and curing agent is 7:3, mix uniformly to obtain a sealing agent;

[0050] S2. Add ethanol to the sealing agent prepared in step S1 to dilute to obtain a sealing solution with a concentration of 50wt%;

[0051] S3. Apply the sealing solution prepared in step S2 to the surface of the cleaned and dried graphite substrate, first apply the sealing solution at a coating amount of 2mg / cm 2 , dry at 80°C, then apply the resin again, each time at a coating amount of 1mg / cm 2 , and finally at a coating amount of 10mg / cm 2 ;

[0052] S4. Cure the graphite substrate obtained in the above steps at 80-100-120°C for 1h respectively to obtain a graphite substrate loaded with resin;

[0053] S5. High-temperature carbonize the graphite substrate loaded with resin at 1500°C under an inert atmosphere to obtain a sealed graphite material.

[0054] Comparative Example 1

[0055] A method for sealing the surface of graphite based on phase separation resin coating derived carbon, comprising the following steps:

[0056] S1. Mix epoxy resin and epoxy soybean oil uniformly at a mass ratio of 5:0.5, then add 651 low molecular polyamide after defoaming, the mass ratio of epoxy resin and curing agent is 7:3, mix uniformly to obtain a sealing agent;

[0057] S2. Add ethanol to the sealing agent prepared in step S1 to dilute to obtain a sealing solution with a concentration of 50wt%;

[0058] S3. Apply the sealing solution prepared in step S2 to the surface of the cleaned and dried graphite substrate, the sealing solution is applied at a coating amount of 1mg / cm 2 ;

[0059] S4. Cure the graphite substrate obtained in the above steps at 80-100-120°C for 1h respectively to obtain a graphite substrate loaded with resin;

[0060] S5. The resin-loaded graphite substrate is subjected to high-temperature carbonization at 1500°C under an inert atmosphere to obtain a sealed graphite material.

[0061] Comparative Example 2

[0062] A method for sealing the surface of graphite based on phase separation resin coating derived carbon, comprising the following steps:

[0063] S1. The epoxy resin and epoxy soybean oil are mixed uniformly at a mass ratio of 20:1, defoaming is performed, and then 651 low-molecular polyamide is added, the mass ratio of the epoxy resin and the curing agent is 7:3, and uniform mixing is performed to obtain a sealing agent;

[0064] S2. Ethanol is added to the sealing agent prepared in step S1 to obtain a sealing solution with a concentration of 50wt% after dilution;

[0065] S3. The sealing solution prepared in step S2 is brushed on the surface of the cleaned and dried graphite substrate, the sealing solution is first applied at a coating amount of 2mg / cm 2 , and after drying at 80°C, resin coating is performed again, and the coating amount is 1mg / cm 2 each time, and the final coating amount is 10mg / cm 2 ;

[0066] S4. The graphite substrate obtained in the above step is cured at 80-100-120°C for 1h each time to obtain a resin-loaded graphite substrate;

[0067] S5. The resin-loaded graphite substrate is subjected to high-temperature carbonization at 1500°C under an inert atmosphere to obtain a sealed graphite material.

[0068] Comparative Example 3

[0069] A method for sealing the surface of graphite based on phase separation resin coating derived carbon, comprising the following steps:

[0070] S1. The epoxy resin and epoxy soybean oil are mixed uniformly at a mass ratio of 1:2, defoaming is performed, and then 651 low-molecular polyamide is added, the mass ratio of the epoxy resin and the curing agent is 7:3, and uniform mixing is performed to obtain a sealing agent;

[0071] S2. Ethanol is added to the sealing agent prepared in step S1 to obtain a sealing solution with a concentration of 50wt% after dilution;

[0072] S3. The sealing solution prepared in step S2 is brushed on the surface of the cleaned and dried graphite substrate, the sealing solution is first applied at a coating amount of 2mg / cm 2 , and after drying at 80°C, resin coating is performed again, and the coating amount is 1mg / cm 2 each time, and the final coating amount is 10mg / cm 2 ;

[0073] S4. The graphite substrate obtained in the above step is cured at 80-100-120°C for 1 h each to obtain a resin-loaded graphite substrate;

[0074] S5. The resin-loaded graphite substrate is subjected to high-temperature carbonization at 1500°C under an inert atmosphere to obtain a sealed graphite material.

[0075] Comparative Example 4

[0076] A method for sealing the surface of graphite based on epoxy resin coating derived carbon, comprising the following steps:

[0077] S1. Apply epoxy resin to the surface of the graphite substrate after cleaning and drying, first apply the sealing solution at a coating amount of 2 mg / cm 2 , dry at 80°C, and then apply the resin again, each time at a coating amount of 1 mg / cm 2 , and finally at a coating amount of 10 mg / cm 2 ;

[0078] S2. The graphite substrate obtained in the above step is cured at 80-100-120°C for 1 h each to obtain a resin-loaded graphite substrate;

[0079] S3. The resin-loaded graphite substrate is subjected to high-temperature carbonization at 1500°C under an inert atmosphere to obtain a sealed graphite material.

[0080] Comparative Example 5

[0081] A method for sealing the surface of graphite based on phase separation resin coating derived carbon, comprising the following steps:

[0082] S1. Mix epoxy resin and epoxy soybean oil uniformly at a mass ratio of 5:0.5, then add 651 low molecular polyamide after defoaming, mix uniformly at a mass ratio of 7:3 of epoxy resin and curing agent to obtain a sealing agent;

[0083] S2. Add ethanol to the sealing agent prepared in step S1 to dilute to obtain a sealing solution with a concentration of 50 wt%;

[0084] S3. Apply the sealing solution prepared in step S2 to the surface of the graphite substrate after cleaning and drying, first apply the sealing solution at a coating amount of 2 mg / cm 2 , dry at 80°C, and then apply the resin again, each time at a coating amount of 1 mg / cm 2 , and finally at a coating amount of 10 mg / cm 2 ;

[0085] S4. The graphite substrate obtained in the above step is cured at 100°C for 2 h to obtain a resin-loaded graphite substrate;

[0086] S5. The resin-loaded graphite substrate is subjected to high-temperature carbonization at 1500°C under an inert atmosphere to obtain a sealed graphite material.

[0087] Comparative Example 6

[0088] A method for sealing the surface of a graphite based on phase separation resin coating-derived carbon, comprising the following steps:

[0089] S1. The epoxy resin and epoxy soybean oil are mixed uniformly at a mass ratio of 5:0.5, defoaming is performed, then 651 low-molecular polyamide is added, the mass ratio of the epoxy resin and the curing agent is 7:3, and uniform mixing is performed to obtain a sealing agent;

[0090] S2. Ethanol is added to the sealing agent prepared in step S1 to obtain a sealing solution with a concentration of 50wt%;

[0091] S3. The sealing solution prepared in step S2 is brushed on the surface of the cleaned and dried graphite substrate, the sealing solution is first coated at a coating amount of 2mg / cm 2 , and after drying at 80°C, the resin is coated again, and each coating amount is 1mg / cm 2 , and the final coating amount is 10mg / cm 2 ;

[0092] S4. The graphite substrate obtained in the above steps is cured at 80-120°C for 1h respectively to obtain a resin-loaded graphite substrate;

[0093] S5. The resin-loaded graphite substrate is subjected to high-temperature carbonization at 1500°C under an inert atmosphere to obtain a sealed graphite material. Performance test: the surface morphology of the impregnated graphite is analyzed using a scanning electron microscope; the porosity of the impregnated graphite sample is measured using a high-performance automatic mercury injection apparatus; and the bending strength of the impregnated graphite sample is measured using a three-point bending method.

[0094]

[0095]

[0096] The test results show that the phase separation epoxy resin impregnation-coating-carbonization sealing effectively reduces the porosity of the graphite product and improves the bending strength. With the increase of the coating amount, the porosity of the graphite product decreases, and when the coating amount reaches 7mg / cm 2 , the porosity reaches a limit. With the increase of the coating amount, the bending strength of the graphite product also gradually increases.

[0097] As Figure 2 , 3As shown, in combination with the scanning electron microscope and the above table, it can be seen that the graphite surface sealing coating obtained by Comparative Example 4 has obvious agglomeration phenomenon, while the sealing coating based on phase separation epoxy resin obtained by Example 1 is more uniform. The more uniform layer is conducive to improve the sealing effect, reduce the porosity of the graphite product, and improve its mechanical strength. In addition, as shown in the following table, the sealing coating of epoxy resin obtained by Comparative Example 5 has obvious cracking after carbonization. The existence of cracks destroys the integrity of the sealing coating, seriously affecting the porosity and mechanical strength of the graphite product. Figure 4

[0098] Obviously, the above examples are only examples for the purpose of clarity, and are not limitations on the embodiments. Based on the above description, other different forms of changes or variations can also be made by those skilled in the art. Here, it is not necessary and impossible to exhaust all the embodiments. The obvious changes or variations derived therefrom are still within the protection scope of the present application.​

Claims

1. A method for sealing pores on graphite surfaces based on carbon derived from phase-separated resin coatings, characterized in that, Includes the following steps: S1. After mixing epoxy resin and epoxy soybean oil in a certain proportion, defoaming is performed, then curing agent is added and mixed evenly to obtain a sealing agent; S2. Add a diluent to the sealing agent prepared in step S1 to dilute and obtain a sealing solution; S3. Apply the sealing solution prepared in step S2 to the surface of the cleaned and dried graphite substrate by brushing or spraying once or multiple times. S4. The graphite substrate obtained in the above steps is cured at a gradient temperature to obtain a resin-loaded graphite substrate; S5. The graphite substrate loaded with resin is carbonized at high temperature under an inert atmosphere to obtain a pore-sealing graphite material; The mass ratio of epoxy resin to epoxy soybean oil is 5-9.5:0.5-5, and the coating amount of the sealing solution on the graphite substrate surface in step S3 is 2-10 mg / cm². 2 In step S4, the gradient curing temperatures are 75–85℃, 95–105℃, and 115–125℃, respectively, for 1 hour each.

2. The method for sealing pores on graphite surfaces based on carbon derived from phase-separated resin coating according to claim 1, characterized in that: The mass ratio of epoxy resin to curing agent is 5.5~7:3~4.

5.

3. The method for sealing pores on graphite surfaces based on carbon derived from phase-separated resin coating according to claim 1, characterized in that: In step S2, the diluent is any one or more of ethanol, acetone, or butanone, and the mass ratio of the sealing agent to the diluent is 1~2:1~2.

4. The method for sealing pores on graphite surfaces based on carbon derived from phase-separated resin coating according to claim 1, characterized in that: The high-temperature carbonization temperature in step S5 is 1500~2800℃.

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