CN103626153B - Boron series catalysts is adopted to prepare the method for graphitizable foams charcoal - Google Patents

Abstract

The invention discloses a method for preparing graphitized foamed carbon by adopting a boron catalyst, and relates to a preparation method of graphitized foamed carbon. The invention aims to solve the technical problems of high graphitization transition temperature and long production time of foamed carbon prepared by the existing method. The method is as follows: 1. Add an emulsifier and mesophase pitch powder to the polyvinyl alcohol solution, and then add a boron catalyst to make a suspension; 2. Carbonize the polyurethane foam that has been treated in step 1, and then put it in a vacuum environment. Heat up and keep warm to get graphitized foam carbon. The average pore diameter of the graphitized carbon foam obtained in the present invention is 800 μm, the density is 0.32 g/cm ³ , the porosity is 86%, the compressive strength is 0.2 Mpa, and the graphitization degree can be increased from 18.4% to 60.0%, and the increase rate can reach 226.1%. , thermal conductivity increased by 400%. The graphitization transition temperature of the foamed carbon prepared by the invention is not high, and the production time is short. The invention belongs to the field of preparation of graphitized foam carbon.

Description

Method for preparing graphitized foam carbon with boron catalyst

technical field

The invention relates to a preparation method of graphitized foamed carbon.

Background technique

The earliest foamed carbon was prepared by Walter Ford in 1964 by pyrolysis of thermosetting phenolic foam. In 1992, Hager of the U.S. Air Force Materials Laboratory used mesophase pitch as the raw material for the first time to prepare foamed carbon by foaming technology. In 1998, James Klett of Oak Ridge National Laboratory in the United States used mesophase pitch as raw material to prepare graphitized foamed carbon by self-volatility foaming method. Graphitized carbon foam.

Graphite foam carbon has many excellent properties, such as adjustable pore size and porosity, low density, high specific surface area, high thermal conductivity and specific thermal conductivity, high electrical conductivity and low thermal expansion coefficient, etc. It also has certain mechanical properties. strength. Since its discovery, it has been widely used in many fields such as heat dissipation and heat exchange of electronic equipment, industrial heat exchangers, and new energy batteries. High-performance carbon foam can also be modified according to the application requirements, such as chemical vapor infiltration (CVI), chemical vapor deposition (CVD), copper plating on the surface, or made into sandwich panels, etc., to form a composite Foam materials strengthen different properties (such as mechanical strength, specific surface area, etc.), thereby expanding the application fields of foam carbon.

At present, the preparation of graphitized foamed carbon mainly adopts the self-volatility foaming method. This method was first proposed by James Klett et al.: grind the mesophase pitch into a powder with a certain fineness (usually below 100 mesh) and add it to the foaming mold. In a high-pressure reactor under the protection of an inert atmosphere (the pressure in the kettle ranges from 3-20MPa, or even higher) at a certain heating rate (1-5°C/min) to 400-600°C and keep it for a certain period of time, so that it Melting and decomposition occur, so that the volatile components of the mesophase pitch volatilize to form a foam pore structure, thereby achieving controlled limited foaming. The structure and performance of the product are controlled by adjusting parameters such as foaming temperature, holding time and pressure, and cooling is obtained Foam charcoal. Graphitized foam carbon can be obtained after the raw material is carbonized and high-temperature graphitized (above 2000°C). The foamed carbon prepared by this method has a pore size of 100-800μm, a density of 0.5-2g/cm3, a compressive strength of more than 1Mpa, and a thermal conductivity greater than 50W/mk. The pore structure is mainly circular, and it has different characteristics depending on the foaming conditions. porosity and porosity.

The various excellent properties of foamed carbon are basically related to its high-temperature graphitization treatment process. High thermal conductivity and specific thermal conductivity, high electrical conductivity and low thermal expansion coefficient are all properties of graphite. Graphitization transformation can occur. However, the graphitization transformation is not only related to the properties of the material itself, but also has a lot to do with the graphitization process system: temperature, time, heating rate, etc.

Generally speaking, the graphitization transformation requires an ultra-high temperature above 2000°C. The higher the temperature and the longer the holding time, the more sufficient the graphitization transformation of the material is, which puts high requirements on the performance of the heating furnace. The graphite heating element needs to be used, which makes the manufacturing process of the heating furnace more complicated and expensive, which may also cause a lot of maintenance and repair costs. In industrial production, Acheson graphitization furnaces are used to graphitize carbon materials. The heating temperature is often as high as 2800°C, and the entire production process lasts for several days. It can be expected that the graphitization production process will generate huge energy consumption.

Therefore, it is necessary to study methods to promote the graphitization transition of foamed carbons.

Contents of the invention

The purpose of the present invention is to provide a method for preparing graphitized foamed carbon using a boron catalyst to solve the technical problems of high graphitization transition temperature and long production time in the prior method for preparing foamed carbon.

The method for preparing graphitized foamed carbon by boron catalyst is as follows:

1. Add an emulsifier to the polyvinyl alcohol solution with a mass concentration of 1-4%, stir and mix well, then add the mesophase pitch powder passed through a 200-mesh standard sieve, then add a boron catalyst, and fully stir and mix at room temperature. Suspension is made, the amount of emulsifier added in the suspension is 1‰-1% of the mass of mesophase pitch powder, the amount of boron-based catalyst added is 1-10% of the mass of mesophase pitch powder, and the amount of boron-based The catalyst is one or a combination of boron carbide, boron simple substance, boron oxide and boric acid;

2. According to the ratio of polyurethane foam to mesophase pitch powder mass ratio of 2-8:1, immerse the polyurethane foam in the suspension so that the suspension is evenly distributed inside the polyurethane foam, and then place the polyurethane foam in a blast drying oven fully dry;

3. Under the protection of argon, the polyurethane foam treated in step 2 is raised to 230-250°C at a rate of 1-3°C/min, and kept for 20-120min, cooled, and then heated in an air atmosphere at a temperature of 5-10°C. The speed of ℃/h is raised to 250-300 ℃, and after 1-7 hours of heat preservation, it is cooled with the furnace. Cool down the furnace to complete the carbonization treatment, then raise the temperature to 2100-2400°C at a rate of 5-20°C/min in a vacuum environment, keep it warm for 0.5-2h, and take it out after cooling with the furnace to obtain graphitized foam carbon.

The method for preparing graphitized foamed carbon by boron catalyst is as follows:

1. Add an emulsifier to the polyvinyl alcohol solution with a mass concentration of 1-4%, stir and mix well, then add the mesophase pitch powder passed through a 200-mesh standard sieve, fully stir and mix at room temperature, and make a suspension. The amount of emulsifier added in the suspension is 1‰-1% of the mass of mesophase pitch powder;

2. According to the ratio of polyurethane foam to mesophase pitch powder mass ratio of 2-8:1, immerse the polyurethane foam in the suspension so that the suspension is evenly distributed inside the polyurethane foam, and then place the polyurethane foam in a blast drying oven fully dry;

3. Under the protection of argon, the polyurethane foam treated in step 2 is raised to 230-250°C at a rate of 1-3°C/min, and kept for 20-120min, cooled, and then heated in an air atmosphere at a temperature of 5-10°C. The speed of ℃/h is raised to 250-300 ℃, and after 1-7 hours of heat preservation, it is cooled with the furnace. The furnace cools down to complete the carbonization treatment;

4. Disperse the boron-based catalyst in the dispersant, the amount of the dispersant added is 0-1% of the mass of the boron-based catalyst to obtain a dispersion, and then immerse the product of step three in the dispersion to make the dispersion in the product of step three The internal distribution is uniform, and then the product of step 3 is heated to 2100-2400 ℃ at a heating rate of 5-20 ℃/min in a vacuum environment, kept for 0.5-2h, and taken out after cooling with the furnace to obtain graphitized foam carbon;

In step 4, the addition amount of the boron-based catalyst is 1-10% of the mass of the mesophase pitch powder. The boron-based catalyst is one of boron carbide, boron simple substance, boron oxide and boric acid or a combination of several of them. The preferred dispersant is tetramethylammonium hydroxide or polyethyleneimine.

The emulsifier described in step one is emulsifier OP-10.

The content of the mesophase pitch powder in the first step is 80-90%, the softening point is 220-230°C, and the particle size is less than 74 μm.

The polyurethane foam described in step 2 has a pore size of 300-1500 μm and a density of 15-60 kg/m ³ , and the polyurethane foam is soaked in NaOH and dried.

Boron is a unique graphitization catalyst, which can promote the graphitization process and reduce the graphitization temperature. It is the only catalyst that can form a solid solution with carbon, and can replace the carbon in the graphite lattice, forming a structure different from other catalytic graphitization. of graphite. For this reason, the present invention proposes to mix a certain amount of boron-based catalyst in the carbon source to promote the graphitization transformation process of the foamed carbon material.

There are different methods to measure the graphitization transition of carbon materials, and the most convenient indicator is the degree of graphitization of the material.

The degree of graphitization is the degree to which the crystals of carbon materials are close to perfect graphite. The most commonly used formula for calculating the degree of graphitization is proposed by Marie and Mering. They believe that the interlayer spacing of completely disordered carbon materials is 0.3440nm, and the structure The interlayer spacing of graphite is 0.3354nm, and the interlayer spacing of all carbon materials should be between the two. The closer the interlayer spacing of the crystal is to perfect graphite, the higher the degree of graphitization. Therefore, the interlayer spacing of the material and the interlayer spacing of single crystal graphite The degree of proximity is used as a measure of the degree of graphitization transformation, that is,

In the formula, d ₀₀₂ is the interlayer distance of graphite crystal, which is calculated by Bragg formula, that is

${\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; 002</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; l</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; q</span>}}$

Among them, l is the incident X-ray wavelength, the unit is nm; q is the diffraction angle corresponding to the (002) crystal plane, the unit is °.

The average pore diameter of the graphitized foamed carbon prepared by the present invention is 800 μm, the density is 0.32 g/cm ³ , the porosity is 86%, and the compressive strength is 0.2 Mpa. The foamed carbon has a good three-dimensional interconnected structure. Due to the addition of boron-based catalysts, the degree of graphitization of carbon foam can be increased from 18.4% to 60.0%, an increase of 226.1%, and the thermal conductivity can be increased by 400%. The graphitization transition temperature of the foamed carbon prepared by the invention is not high, and the production time is short.

Detailed ways

The technical solution of the present invention is not limited to the specific embodiments listed below, but also includes any combination of the specific embodiments.

Specific embodiment one: adopt boron series catalyst to prepare the method for graphitized foamed carbon as follows:

1. Add an emulsifier to the polyvinyl alcohol solution with a mass concentration of 1-4%, stir and mix well, then add the mesophase pitch powder passed through a 200-mesh standard sieve, then add a boron catalyst, and fully stir and mix at room temperature. Suspension is made, the amount of emulsifier added in the suspension is 1‰-1% of the mass of mesophase pitch powder, the amount of boron-based catalyst added is 1-10% of the mass of mesophase pitch powder, and the amount of boron-based The catalyst is one or a combination of boron carbide, boron simple substance, boron oxide and boric acid;

2. According to the ratio of polyurethane foam to mesophase pitch powder mass ratio of 2-8:1, immerse the polyurethane foam in the suspension so that the suspension is evenly distributed inside the polyurethane foam, and then place the polyurethane foam in a blast drying oven fully dry;

3. Under the protection of argon, the polyurethane foam treated in step 2 is raised to 230-250°C at a rate of 1-3°C/min, and kept for 20-120min, cooled, and then heated in an air atmosphere at a temperature of 5-10°C. The speed of ℃/h is raised to 250-300 ℃, and after 1-7 hours of heat preservation, it is cooled with the furnace. Cool down the furnace to complete the carbonization treatment, then raise the temperature to 2100-2400°C at a rate of 5-20°C/min in a vacuum environment, keep it warm for 0.5-2h, and take it out after cooling with the furnace to obtain graphitized foam carbon.

When the boron-based catalyst described in this embodiment is a composition, the ratios between the components are arbitrary.

Embodiment 2: This embodiment is different from Embodiment 1 in that the emulsifier described in step 1 is emulsifier OP-10. Others are the same as in the first embodiment.

Embodiment 3: This embodiment differs from Embodiment 1 or Embodiment 2 in that the content of mesophase pitch powder in step 1 is 80-90%, the softening point is 220-230°C, and the particle size is less than 74 μm. Others are different from the first or second specific embodiment.

Embodiment 4: This embodiment differs from Embodiments 1 to 3 in that the polyurethane foam described in step 2 has a pore size of 300-1500 μm and a density of 15-60 kg/m ³ , and the polyurethane foam is soaked in NaOH and dried . Others are the same as those in the first to third specific embodiments.

The process of adopting NaOH soaking treatment polyurethane foam in the present embodiment is as follows:

Cut the polyurethane foam into small pieces of 100*100*20mm, soak it in NaOH solution with a mass concentration of 10%, wash it with water after soaking for 6-72 hours, and then dry it in an oven for 8-15 hours.

Embodiment 5: This embodiment differs from Embodiments 1 to 4 in that the amount of emulsifier added to the suspension described in step 1 is 0.5% of the mass of the mesophase pitch powder. Others are the same as one of the specific embodiments 1 to 4.

Specific embodiment six: the present embodiment adopts boron series catalyst to prepare the method for graphitized foamed carbon as follows:

1. Add an emulsifier to the polyvinyl alcohol solution with a mass concentration of 1-4%, stir and mix well, then add the mesophase pitch powder passed through a 200-mesh standard sieve, fully stir and mix at room temperature, and make a suspension. The amount of emulsifier added in the suspension is 1‰-1% of the mass of mesophase pitch powder;

2. According to the ratio of polyurethane foam to mesophase pitch powder mass ratio of 2-8:1, immerse the polyurethane foam in the suspension so that the suspension is evenly distributed inside the polyurethane foam, and then place the polyurethane foam in a blast drying oven fully dry;

3. Under the protection of argon, the polyurethane foam treated in step 2 is raised to 230-250°C at a rate of 1-3°C/min, and kept for 20-120min, cooled, and then heated in an air atmosphere at a temperature of 5-10°C. The speed of ℃/h is raised to 250-300 ℃, and after 1-7 hours of heat preservation, it is cooled with the furnace. The furnace cools down to complete the carbonization treatment;

4. Disperse the boron-based catalyst in the dispersant, the amount of the dispersant added is 0-1% of the mass of the boron-based catalyst to obtain a dispersion, and then immerse the product of step three in the dispersion to make the dispersion in the product of step three The internal distribution is uniform, and then the product of step 3 is heated to 2100-2400 ℃ at a heating rate of 5-20 ℃/min in a vacuum environment, kept for 0.5-2h, and taken out after cooling with the furnace to obtain graphitized foam carbon;

In step 4, the addition amount of the boron-based catalyst is 1-10% of the mass of the mesophase pitch powder. The boron-based catalyst is one of boron carbide, boron simple substance, boron oxide and boric acid or a combination of several of them. The preferred dispersant is tetramethylammonium hydroxide or polyethyleneimine.

When the boron-based catalyst described in this embodiment is a composition, the ratios between the components are arbitrary.

Embodiment 7: The difference between this embodiment and Embodiment 6 or 7 is that the emulsifier described in step 1 is emulsifier OP-10. Others are the same as in Embodiment 6 or 7.

Embodiment 8: This embodiment differs from Embodiments 6 to 7 in that the content of mesophase pitch powder in step 1 is 80-90%, the softening point is 220-230°C, and the particle size is less than 74 μm. Others are the same as one of the sixth to seventh embodiments.

Specific embodiment nine: the difference between this embodiment and one of specific embodiments six to eight is that the polyurethane foam described in step 2 has a pore size of 300-1500 μm and a density of 15-60 kg/m ³ , and the polyurethane foam is soaked in NaOH and dry. Others are the same as one of the sixth to eighth specific embodiments.

The process of adopting NaOH soaking treatment polyurethane foam in the present embodiment is as follows:

Cut the polyurethane foam into small pieces of 100*100*20mm, soak it in NaOH solution with a mass concentration of 10%, wash it with water after soaking for 6-72 hours, and then dry it in an oven for 8-15 hours.

Embodiment 10: This embodiment differs from Embodiment 6 to Embodiment 9 in that the amount of emulsifier added to the suspension described in step 1 is 0.5% of the mass of the mesophase pitch powder. Others are the same as one of the sixth to ninth specific embodiments.

Adopt following experiment verification effect of the present invention:

experiment one:

The method for preparing graphitized foamed carbon by boron catalyst is as follows:

1. Polyurethane foam with a pore size of 1300 μm and a density of 34 g/ ^cm3 is cut into small pieces of 100*100*20 mm, soaked in NaOH solution with a mass concentration of 10%, washed with water after 6 hours, and dried in an oven for 8 hours ;

Add an emulsifier to the polyvinyl alcohol solution with a mass concentration of 3%, stir and mix well, then add the mesophase pitch powder passed through a 200-mesh standard sieve, then add a boron catalyst, stir and mix well at room temperature to make a suspension , the amount of emulsifier added in the suspension is 1‰ of the mass of mesophase pitch powder, the amount of boron-based catalyst added is 3% of the mass of mesophase pitch powder, and the boron-based catalyst is boron carbide micropowder (B4C, powder Particle size 2-5μm);

2. According to the ratio of polyurethane foam to mesophase pitch powder mass ratio of 4:1, immerse the polyurethane foam in the suspension so that the suspension is evenly distributed inside the polyurethane foam, and then place the polyurethane foam in a blast drying oven to fully dry ;

3. Under the protection of argon, the polyurethane foam treated in step 2 is raised to 235°C at a rate of 2°C/min, kept for 60 minutes, cooled, and then raised to 300°C at a rate of 10°C/h in an air atmosphere. ℃, keep warm for 3 hours, then cool with the furnace, raise the temperature up to 1000°C at a rate of 5°C/min under the protection of inert gas or in a vacuum environment, cool down with the furnace after holding for 1 hour, complete the carbonization treatment, and then in a vacuum environment at 10°C/min Raise the temperature to 2200°C at a heating rate of min, keep it warm for 2 hours, take it out after cooling with the furnace, and obtain graphitized foamed carbon.

The graphitized carbon foam prepared in this experiment has an average pore size of 800 μm, a density of 0.32 g/cm ³ , a porosity of 86%, and a compressive strength of 0.2 Mpa. The foam carbon has a good three-dimensional interconnected structure.

Due to the addition of boron carbide (B4C), the degree of graphitization of carbon foam increased from 18.4% to 60.0%, an increase of 226.1%, and the thermal conductivity increased by 400%.

Experiment 2:

The method for preparing graphitized foamed carbon by boron catalyst is as follows:

1. Polyurethane foam with a pore size of 1300 μm and a density of 34 g/ ^cm3 is cut into small pieces of 100*100*20 mm, soaked in NaOH solution with a mass concentration of 10%, washed with water after 6 hours, and dried in an oven for 8 hours ;

Add an emulsifier to the polyvinyl alcohol solution with a mass concentration of 3%, stir and mix well, then add the mesophase pitch powder passed through a 200-mesh standard sieve, then add a boron catalyst, stir and mix well at room temperature to make a suspension , the amount of emulsifier added in the suspension is 1‰ of the mass of mesophase pitch powder, the amount of boron-based catalyst added is 5% of the mass of mesophase pitch powder, and the boron-based catalyst is boron carbide micropowder (B4C, powder Particle size 2-5μm);

2. According to the ratio of polyurethane foam to mesophase pitch powder mass ratio of 4:1, immerse the polyurethane foam in the suspension so that the suspension is evenly distributed inside the polyurethane foam, and then place the polyurethane foam in a blast drying oven to fully dry ;

3. Under the protection of argon, the polyurethane foam treated in step 2 is raised to 235°C at a rate of 2°C/min, kept for 60 minutes, cooled, and then raised to 300°C at a rate of 10°C/h in an air atmosphere. ℃, keep warm for 3 hours and then cool with the furnace, under the protection of inert gas or vacuum environment, the temperature rises to 1000 ℃ at a rate of 5 ℃/min, and after 1 hour of heat preservation, cool down with the furnace to complete the carbonization treatment;

4. Disperse the boron-based catalyst in the dispersant. The amount of dispersant added is 0.5% of the mass of the boron-based catalyst to obtain a dispersion, and then immerse the product of step 3 in the dispersion to distribute the dispersion inside the product of step 3. Uniform (dried after soaking in vacuum for 1 hour, the boron carbide content on the surface of the foam carbon after drying was measured to be 1.04%), and then the product in step 3 was heated up to 2200°C at a heating rate of 10°C/min in a vacuum environment , keep warm for 2 hours, take it out after cooling with the furnace, and obtain graphitized foamed carbon;

In step 4, the addition amount of the boron-based catalyst is 1% of the mass of the mesophase pitch powder, the boron-based catalyst is boron carbide, and the dispersant is tetramethylammonium hydroxide.

The average pore size of the graphitized carbon foam obtained in this experiment is 800 μm, the density is 0.32 g/cm ³ , the porosity is 86%, and the compressive strength is 0.2 Mpa. Due to the addition of boron carbide (B4C), the degree of graphitization of carbon foam increased from 18.4% to 48.2%, an increase of 162.0%, and the thermal conductivity increased by 250%.

Experiment three:

The method for preparing graphitized foamed carbon by boron catalyst is as follows:

1. Polyurethane foam with a pore size of 1300 μm and a density of 34 g/ ^cm3 is cut into small pieces of 100*100*20 mm, soaked in NaOH solution with a mass concentration of 10%, washed with water after 6 hours, and dried in an oven for 8 hours ;

Add an emulsifier to the polyvinyl alcohol solution with a mass concentration of 3%, stir and mix well, then add the mesophase pitch powder passed through a 200-mesh standard sieve, then add a boron catalyst, stir and mix well at room temperature to make a suspension , the amount of emulsifier added in the suspension is 15% of the mass of mesophase pitch powder, the amount of boron catalyst added is 3% of the mass of mesophase pitch powder, and the boron catalyst is boric acid;

2. According to the ratio of polyurethane foam to mesophase pitch powder mass ratio of 4:1, immerse the polyurethane foam in the suspension so that the suspension is evenly distributed inside the polyurethane foam, and then place the polyurethane foam in a blast drying oven to fully dry ;

3. Under the protection of argon, the polyurethane foam treated in step 2 is raised to 235°C at a rate of 2°C/min, kept for 60 minutes, cooled, and then raised to 300°C at a rate of 10°C/h in an air atmosphere. ℃, keep warm for 3 hours, then cool with the furnace, raise the temperature up to 1000°C at a rate of 5°C/min under the protection of inert gas or in a vacuum environment, cool down with the furnace after holding for 1 hour, complete the carbonization treatment, and then in a vacuum environment at 10°C/min Raise the temperature to 2200°C at a heating rate of min, keep it warm for 2 hours, take it out after cooling with the furnace, and obtain graphitized foamed carbon.

The average pore size of the graphitized carbon foam prepared in this experiment is 800 μm, the density is 0.32 g/cm ³ , the porosity is 86%, and the compressive strength is 0.1 Mpa. The foam carbon has a good three-dimensional interconnected structure. Due to the addition of boric acid (H3BO3), the degree of graphitization of carbon foam increased from 18.4% to 36.3%, an increase of 97.3%, and the thermal conductivity increased by 200%.

It can be seen that the addition of a large amount of boric acid reduces the compressive strength of foam carbon, but does not change its pore structure and density.

Experiment 4:

The method for preparing graphitized foamed carbon by boron catalyst is as follows:

1. Polyurethane foam with a pore size of 1300 μm and a density of 34 g/ ^cm3 is cut into small pieces of 100*100*20 mm, soaked in NaOH solution with a mass concentration of 10%, washed with water after 6 hours, and dried in an oven for 8 hours ;

Add an emulsifier to the polyvinyl alcohol solution with a mass concentration of 3%, stir and mix well, then add the mesophase pitch powder passed through a 200-mesh standard sieve, then add a boron catalyst, stir and mix well at room temperature to make a suspension , the amount of emulsifier added in the suspension is 2% of the mass of mesophase pitch powder, the amount of boron-based catalyst added is 3% of the mass of mesophase pitch powder, and the boron-based catalyst is simple boron;

2. According to the ratio of polyurethane foam to mesophase pitch powder mass ratio of 4:1, immerse the polyurethane foam in the suspension so that the suspension is evenly distributed inside the polyurethane foam, and then place the polyurethane foam in a blast drying oven to fully dry ;

3. Under the protection of argon, the polyurethane foam treated in step 2 is raised to 235°C at a rate of 2°C/min, kept for 60 minutes, cooled, and then raised to 300°C at a rate of 10°C/h in an air atmosphere. ℃, keep warm for 3 hours, then cool with the furnace, raise the temperature up to 1000°C at a rate of 5°C/min under the protection of inert gas or in a vacuum environment, cool down with the furnace after holding for 1 hour, complete the carbonization treatment, and then in a vacuum environment at 10°C/min Raise the temperature to 2200°C at a heating rate of min, keep it warm for 2 hours, take it out after cooling with the furnace, and obtain graphitized foamed carbon.

The graphitized carbon foam prepared in this experiment has an average pore size of 800 μm, a density of 0.32 g/cm ³ , a porosity of 86%, and a compressive strength of 0.2 Mpa. The foam carbon has a good three-dimensional interconnected structure.

Due to the addition of boron, the degree of graphitization of carbon foam increased from 18.4% to 51.2%, an increase of 178.3%, and the thermal conductivity also increased by 300%.

Claims (6)

1. adopt boron series catalyst to prepare the method for graphitized foamed carbon, it is characterized in that adopting boron series catalyst to prepare the method for graphitized foamed carbon is as follows: 1. Add an emulsifier to the polyvinyl alcohol solution with a mass concentration of 1-4%. After stirring and mixing, add the mesophase pitch powder passed through a 200-mesh standard sieve, then add a boron catalyst, and fully stir and mix at room temperature. Suspension is made, the amount of emulsifier added in the suspension is 1‰-1% of the mass of mesophase pitch powder, the amount of boron-based catalyst added is 1-10% of the mass of mesophase pitch powder, and the boron-based The catalyst is one or a combination of boron carbide, boron simple substance, boron oxide and boric acid; 2. According to the ratio of polyurethane foam to mesophase pitch powder mass ratio of 2-8:1, immerse the polyurethane foam in the suspension so that the suspension is evenly distributed inside the polyurethane foam, and then place the polyurethane foam in a blast drying oven fully dry; 3. Under the protection of argon, the polyurethane foam treated in step 2 is raised to 230-250°C at a rate of 1-3°C/min, and kept for 20-120min, cooled, and then heated in an air atmosphere at a temperature of 5-10°C. The speed of ℃/h is raised to 250-300 ℃, and after 1-7 hours of heat preservation, it is cooled with the furnace. Cool down the furnace, complete the carbonization treatment, then raise the temperature to 2100-2400°C at a heating rate of 5-20°C/min in a vacuum environment, keep it warm for 0.5-2h, and take it out after cooling with the furnace to obtain graphitized foam carbon; The emulsifier described in step 1 is emulsifier OP-10, The polyurethane foam described in step 2 has a pore size of 300-1500 μm and a density of 15-60 kg/m ³ , and the polyurethane foam is soaked in NaOH and dried. 2. the method for preparing graphitized foamed carbon using a boron catalyst according to claim 1, characterized in that the content of the mesophase pitch powder described in step 1 is 80-90%, the softening point is 220-230 ° C, the particle size Less than 74μm. 3. The method for preparing graphitized foamed carbon using a boron catalyst according to claim 1, wherein the amount of emulsifier added in the suspension described in step 1 is 0.5% of the mass of mesophase pitch powder. 4. adopt boron series catalyst to prepare the method for graphitized foamed carbon, it is characterized in that adopting boron series catalyst to prepare the method for graphitized foamed carbon is as follows: 1. Add an emulsifier to a polyvinyl alcohol solution with a mass concentration of 1-4%, stir and mix, then add mesophase pitch powder passed through a 200-mesh standard sieve, fully stir and mix at room temperature, and make a suspension. The amount of emulsifier added in the suspension is 1‰-1% of the mass of mesophase pitch powder; 2. According to the ratio of polyurethane foam to mesophase pitch powder mass ratio of 2-8:1, immerse the polyurethane foam in the suspension so that the suspension is evenly distributed inside the polyurethane foam, and then place the polyurethane foam in a blast drying oven fully dry; 3. Under the protection of argon, the polyurethane foam treated in step 2 is raised to 230-250°C at a rate of 1-3°C/min, and kept for 20-120min, cooled, and then heated in an air atmosphere at a temperature of 5-10°C. The speed of ℃/h is raised to 250-300 ℃, and after 1-7 hours of heat preservation, it is cooled with the furnace. The furnace cools down to complete the carbonization treatment; 4. Disperse the boron-based catalyst in the dispersant. The amount of dispersant added is 0-1% of the mass of the boron-based catalyst to obtain a dispersion, and then the product of step three is immersed in the dispersion to make the dispersion in the product of step three The internal distribution is uniform, and then the product of step 3 is heated to 2100-2400 ℃ at a heating rate of 5-20 ℃/min in a vacuum environment, kept for 0.5-2h, and taken out after cooling with the furnace to obtain graphitized foam carbon; In step 4, the amount of the boron-based catalyst added is 1-10% of the mass of the mesophase pitch powder. The boron-based catalyst is one of boron carbide, boron simple substance, boron oxide and boric acid or a combination of several of them. The dispersant is tetramethylammonium hydroxide or polyethyleneimine; The emulsifier described in step 1 is emulsifier OP-10; The polyurethane foam described in step 2 has a pore size of 300-1500 μm and a density of 15-60 kg/m ³ , and the polyurethane foam is soaked in NaOH and dried. 5. The method for preparing graphitized foamed carbon using a boron catalyst according to claim 4, characterized in that the content of the mesophase pitch powder described in step 1 is 80-90%, the softening point is 220-230°C, and the particle size Less than 74μm. 6. The method for preparing graphitized foamed carbon using a boron catalyst according to claim 4, characterized in that the amount of emulsifier added in the suspension described in step 1 is 0.5% of the mass of mesophase pitch powder.