Graphite surface hole sealing method based on phase separation resin coating derived carbon

Abstract

The invention provides a graphite surface hole sealing method based on phase separation resin coating derived carbon, which comprises the following steps: S1, uniformly mixing epoxy resin and epoxidized soybean oil in proportion, defoaming, adding a curing agent, and uniformly mixing to obtain a hole sealing agent; s2, adding a diluent into the hole sealing agent prepared in the step S1, and diluting to obtain a hole sealing solution; s3, brushing or spraying the hole sealing solution prepared in the step S2 on the surface of the cleaned and dried graphite base material for one or more times; s4, curing the graphite base material obtained in the previous step at a gradient temperature to obtain a resin-loaded graphite base material; and S5, carrying out high-temperature carbonization on the resin-loaded graphite base material in an inert atmosphere to obtain the hole-sealing graphite material. According to the invention, the carbon formed by high-temperature graphitization of the resin coating coated on the graphite surface is used for sealing holes on the graphite surface, so that the graphite surface has good coating bonding property, the durability of graphite hole sealing is further improved, and the service life of a graphite product is prolonged.

Description

Technical Field

[0001] The invention relates to the field of graphite material pore sealing, and in particular to a graphite surface pore sealing method based on phase separation resin coating derived carbon. Background Art

[0002] Graphite sealing is to form a protective film or coating on the graphite surface 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, thermal management, corrosion protection, etc. At the same time, sealing can also improve the stability, durability and service life of graphite materials to meet a wider range of application needs. Common graphite sealing methods include: chemical vapor deposition (CVD), in which a gas precursor (such as methane) decomposes under high temperature conditions to deposit a thin film on the graphite surface to seal the pores; coating / surface modification, in which a material with sealing ability (such as resin, polymer, oxide, etc.) is coated on the graphite surface to form a protective layer. Electrochemical sealing, using electrochemical methods in an electrolyte, deposits metal or non-metallic films on the graphite surface to seal the pores. This method is commonly used in battery electrode materials and can provide a sealing effect without destroying the graphite structure. For applications that require improving the chemical stability, high temperature resistance and mechanical strength of graphite, coating with resin and sealing by high-temperature carbonization is an effective treatment method, and compared with methods such as CVD, it is simple to operate and easier to apply in practice. Summary of the invention

[0003] Technical problem to be solved: The purpose of the present invention is to provide a method for sealing the graphite surface based on phase separation resin coating derived carbon, and the graphite surface is sealed by using the carbon formed after high-temperature graphitization of the resin coating coated on the graphite surface.

[0004] Technical solution: A method for sealing the surface of graphite based on phase separation resin coating derived carbon, comprising the following steps: S1. mixing epoxy resin and epoxy soybean oil in proportion, adding a curing agent after defoaming, and mixing evenly to obtain a sealing agent; S2. Add a diluent to the sealing agent prepared in step S1 to dilute the sealing solution; S3. Brushing or spraying the sealing solution prepared in step S2 once or multiple times on the surface of the cleaned and dried graphite substrate; S4. The graphite substrate obtained in the above step is cured at a gradient temperature to obtain a graphite substrate loaded with a resin; S5. Carbonizing the resin-loaded graphite substrate at high temperature under an inert atmosphere to obtain a sealed graphite material. Preferably, the mass ratio of the epoxy resin to the epoxidized soybean oil is 5-9.5:0.5-5. Preferably, the mass ratio of the epoxy resin to the curing agent is 5.5-7:3-4.5. Preferably, the diluent in step S2 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. Preferably, the coating amount of the sealing solution on the surface of the graphite substrate in step S3 is 2-10 mg / cm 2 . Preferably, the temperature of the gradient curing in step S4 is 75-85° C., 95-105° C., and 115-125° C., respectively, for 1 hour each. Preferably, the temperature of high temperature carbonization in step S5 is 1500-2800°C. Beneficial effects: The graphite sealing method of the present invention has the following advantages: 1. Use phase separation technology to form multiphase resin in the resin slurry, and use the different surface tensions of epoxy soybean oil and epoxy resin to induce the epoxy resin to form microspherical droplets in the multiphase resin slurry. With the subsequent curing and high-temperature carbonization process, spherical resin and derived carbon are formed to achieve the pore sealing effect on the graphite surface; 2. The microsphere droplets formed by the phase separation technology and the microsphere resin formed by the solidification have good bonding with the graphite surface, so that the derived sealing carbon coating has good coating bonding, thereby improving the durability of the graphite sealing and the service life of the graphite products; 3. The phase separation resin coating of the present invention can shrink and pyrolyze locally within each microsphere during high-temperature pyrolysis, and form a uniform and dense pore-sealing carbon coating under the accumulation of multiple layers of microspheres, thereby avoiding the cracking caused by shrinkage of a single homogeneous epoxy resin during pyrolysis, and improving the product yield and production efficiency; 4. The graphite surface sealing technology involved in the present invention has simple requirements on equipment and process, low process cost and easy operation. At the same time, compared with CVD sealing, electrochemical sealing and other technologies, it is safer and more environmentally friendly and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 It is an operation flow chart of a graphite surface sealing technology based on phase separation resin coating derived carbon provided by the present invention; Figure 2 This is a scanning electron microscope image of a graphite surface sealed by a graphite surface sealing technology based on phase separation resin coating derived carbon obtained in Example 1; Figure 3 This is a scanning electron microscope image of the single homogeneous epoxy resin coating obtained in Comparative Example 4 after high-temperature carbonization on the graphite surface; Figure 41 is a scanning electron microscope image of the graphite surface after sealing obtained in Example 1 (a) and Comparative Example 5 (b) using the graphite surface sealing technology based on phase separation resin coating derived carbon. DETAILED DESCRIPTION The present invention will be further described below in conjunction with embodiments, which are explanations of the present invention and are not limited to the following embodiments: Example 1 A method for sealing graphite surfaces based on phase separation resin coating derived carbon comprises the following steps: S1. The epoxy resin and epoxy soybean oil were mixed in a mass ratio of 5:0.5, and then defoamed and added with 651 low molecular weight polyamide, the mass ratio of epoxy resin and curing agent was 7:3, and mixed to obtain a sealing agent; S2. Add ethanol to the sealing agent prepared in step S1 and dilute to obtain a sealing solution having a concentration of 50 wt %; 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 2 mg / cm 2 After drying at 80°C, the resin was applied again, with the coating amount of 1 mg / cm 2 The final coating amount is 10mg / cm 2 ; S4. The graphite substrate obtained in the above step is cured at 80-100-120°C for 1h each to obtain a graphite substrate loaded with a resin; 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. Example 2 A method for sealing graphite surfaces based on phase separation resin coating derived carbon comprises the following steps: S1. The epoxy resin and epoxy soybean oil were mixed in a mass ratio of 5:0.5, and then defoamed and added with 651 low molecular weight polyamide, the mass ratio of epoxy resin and curing agent was 7:3, and mixed to obtain a sealing agent; S2. Add ethanol to the sealing agent prepared in step S1 and dilute to obtain a sealing solution having a concentration of 50 wt %; 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 2 mg / cm 2 After drying at 80°C, the resin was applied again, with the coating amount of 1 mg / cm 2 The final coating amount is 6 mg / cm 2 ; S4. The graphite substrate obtained in the above step is cured at 80-100-120°C for 1h each to obtain a graphite substrate loaded with a resin; 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. Example 3 A method for sealing graphite surfaces based on phase separation resin coating derived carbon comprises the following steps: S1. The epoxy resin and epoxy soybean oil were mixed in a mass ratio of 5:0.5, and then defoamed and added with 651 low molecular weight polyamide, the mass ratio of epoxy resin and curing agent was 7:3, and mixed to obtain a sealing agent; S2. Add ethanol to the sealing agent prepared in step S1 and dilute to obtain a sealing solution having a concentration of 50 wt %; S3. Apply the sealing solution prepared in step S2 to the surface of the cleaned and dried graphite substrate. The sealing solution is applied in an amount of 2 mg / cm 2 ; S4. The graphite substrate obtained in the above step is cured at 80-100-120°C for 1h each to obtain a graphite substrate loaded with a resin; 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. Example 4 A method for sealing graphite surfaces based on phase separation resin coating derived carbon comprises the following steps: S1. The epoxy resin and epoxy soybean oil were mixed in a mass ratio of 9.5:5, and then defoamed and added with 651 low molecular weight polyamide, the mass ratio of epoxy resin and curing agent was 7:3, and mixed to obtain a sealing agent; S2. Add ethanol to the sealing agent prepared in step S1 and dilute to obtain a sealing solution having a concentration of 50 wt %; 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 2 mg / cm 2 After drying at 80°C, the resin was applied again, with the coating amount of 1 mg / cm 2 The final coating amount is 10mg / cm 2 ; S4. The graphite substrate obtained in the above step is cured at 80-100-120°C for 1h each to obtain a graphite substrate loaded with a resin; 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. Comparative Example 1 A method for sealing graphite surfaces based on phase separation resin coating derived carbon comprises the following steps: S1. The epoxy resin and epoxy soybean oil were mixed in a mass ratio of 5:0.5, and then defoamed and added with 651 low molecular weight polyamide, the mass ratio of epoxy resin and curing agent was 7:3, and mixed to obtain a sealing agent; S2. Add ethanol to the sealing agent prepared in step S1 and dilute to obtain a sealing solution having a concentration of 50 wt %; S3. Apply the sealing solution prepared in step S2 to the surface of the graphite substrate after cleaning and drying, and the sealing solution is applied in an amount of 1 mg / cm 2 ; S4. The graphite substrate obtained in the above step is cured at 80-100-120°C for 1h each to obtain a graphite substrate loaded with a resin; 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. Comparative Example 2 A method for sealing graphite surfaces based on phase separation resin coating derived carbon comprises the following steps: S1. The epoxy resin and epoxy soybean oil were mixed in a mass ratio of 20:1, and then 651 low molecular weight polyamide was added after defoaming, the mass ratio of epoxy resin and curing agent was 7:3, and mixed to obtain a sealing agent; S2. Add ethanol to the sealing agent prepared in step S1 and dilute to obtain a sealing solution having a concentration of 50 wt %; 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 2 mg / cm 2 After drying at 80°C, the resin was applied again, with the coating amount of 1 mg / cm 2 The final coating amount is 10mg / cm 2 ;; S4. The graphite substrate obtained in the above step is cured at 80-100-120°C for 1h each to obtain a graphite substrate loaded with a resin; 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. Comparative Example 3 A method for sealing graphite surfaces based on phase separation resin coating derived carbon comprises the following steps: S1. The epoxy resin and the epoxy soybean oil were mixed in a mass ratio of 1:2, and after defoaming, 651 low molecular weight polyamide, epoxy resin and curing agent were added in a mass ratio of 7:3, and mixed to obtain a sealing agent; S2. Add ethanol to the sealing agent prepared in step S1 and dilute to obtain a sealing solution having a concentration of 50 wt %; 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 2 mg / cm 2 After drying at 80°C, the resin was applied again, with the coating amount of 1 mg / cm 2 The final coating amount is 10mg / cm 2 ; S4. The graphite substrate obtained in the above step is cured at 80-100-120°C for 1h each to obtain a graphite substrate loaded with a resin; 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. Comparative Example 4 A method for sealing graphite surfaces based on epoxy resin coating derived carbon comprises the following steps: S1. Apply epoxy resin to the surface of the cleaned and dried graphite substrate. First, apply the sealing solution at a coating amount of 2 mg / cm 2 After drying at 80°C, the resin was applied again, with the coating amount of 1 mg / cm 2 The final coating amount is 10mg / cm 2 ; S2. The graphite substrate obtained in the above step was cured at 80-100-120°C for 1h each to obtain a graphite substrate loaded with a resin; S3. The resin-loaded graphite substrate is subjected to high-temperature carbonization at 1500° C. in an inert atmosphere to obtain a sealed graphite material. Comparative Example 5 A method for sealing graphite surfaces based on phase separation resin coating derived carbon comprises the following steps: S1. The epoxy resin and epoxy soybean oil were mixed in a mass ratio of 5:0.5, and then defoamed and added with 651 low molecular weight polyamide, the mass ratio of epoxy resin and curing agent was 7:3, and mixed to obtain a sealing agent; S2. Add ethanol to the sealing agent prepared in step S1 and dilute to obtain a sealing solution having a concentration of 50 wt %; 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 2 mg / cm 2 After drying at 80°C, the resin was applied again, with the coating amount of 1 mg / cm 2 The final coating amount is 10mg / cm 2 ; S4. The graphite substrate obtained in the above step was cured at 100° C. for 2 h to obtain a graphite substrate loaded with a resin; 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. Comparative Example 6 A method for sealing graphite surfaces based on phase separation resin coating derived carbon comprises the following steps: S1. The epoxy resin and epoxy soybean oil were mixed in a mass ratio of 5:0.5, and then defoamed and added with 651 low molecular weight polyamide, the mass ratio of epoxy resin and curing agent was 7:3, and mixed to obtain a sealing agent; S2. Add ethanol to the sealing agent prepared in step S1 and dilute to obtain a sealing solution having a concentration of 50 wt %; 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 2 mg / cm 2 After drying at 80°C, the resin was applied again, with the coating amount of 1 mg / cm 2 The final coating amount is 10mg / cm 2 ; S4. The graphite substrate obtained in the above step was cured at 80-120°C for 1h to obtain a graphite substrate loaded with a resin; S5. The resin-loaded graphite substrate is subjected to high-temperature carbonization at 1500°C in 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 fully automatic mercury intrusion instrument; and the flexural strength of the impregnated graphite sample is measured using a three-point bending method. The test results show that the phase separation epoxy resin impregnation coating-carbonization sealing effectively reduces the porosity of graphite products and improves the bending strength. As the coating amount increases, the porosity of graphite products decreases. When the coating amount reaches 7mg / cm 2 When the coating amount increases, the bending strength of graphite products also increases gradually. like Figure 2 , 3 As shown, combined with the scanning electron microscope and the above table, it can be seen that the graphite surface sealing coating obtained in Comparative Example 4 has obvious agglomeration phenomenon, while the sealing coating based on the phase separation epoxy resin obtained in Example 1 is more uniform. A more uniform layer is conducive to improving the sealing effect, reducing the porosity of the graphite product, and improving its mechanical strength. In addition, Figure 4 As shown, the epoxy resin sealing coating obtained in Comparative Example 5 exhibited obvious cracks after carbonization. The presence of the cracks destroyed the integrity of the sealing coating, seriously affecting the porosity and mechanical strength of the graphite product. 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 invention.

Claims

1. A method for sealing graphite surfaces based on phase separation resin coating derived carbon, characterized in that: The following steps are involved: S1. After the epoxy resin and epoxy soybean oil are mixed evenly in proportion, a curing agent is added after defoaming, and mixed evenly to obtain a sealing agent; S2. Add a diluent to the sealing agent prepared in step S1 to dilute the sealing solution; S3. Brushing or spraying the sealing solution prepared in step S2 once or multiple times on the surface of the cleaned and dried graphite substrate; S4. The graphite substrate obtained in the above step is cured at a gradient temperature to obtain a graphite substrate loaded with a resin; S5. Carbonizing the resin-loaded graphite substrate at high temperature under an inert atmosphere to obtain a sealed graphite material.

2. The method for sealing graphite surface based on phase separation resin coating derived carbon according to claim 1, characterized in that: The mass ratio of the epoxy resin to the epoxy soybean oil is 5-9.5:0.5-5.

3. The method for sealing graphite surface based on phase separation resin coating derived carbon according to claim 1, characterized in that: The mass ratio of the epoxy resin to the curing agent is 5.5-7:3-4.

5.

4. The method for sealing graphite surface based on phase separation resin coating derived carbon 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.

5. The method for sealing graphite surface based on phase separation resin coating derived carbon according to claim 1, characterized in that: The coating amount of the sealing solution on the surface of the graphite substrate in step S3 is 2-10 mg / cm 2 .

6. The method for sealing graphite surface based on phase separation resin coating derived carbon according to claim 1, characterized in that: The temperature of the gradient curing in step S4 is 75-85° C., 95-105° C., and 115-125° C. for 1 hour each.

7. The method for sealing graphite surface based on phase separation resin coating derived carbon according to claim 1, characterized in that: The temperature of high temperature carbonization in step S5 is 1500-2800°C.

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