A method for preparing a high-strength foamed carbon material

Abstract

The application discloses a preparation method of high-strength foam carbon material, and the pore diameter of the prepared foam carbon is 1-30 mu m. The foam carbon material has low thermal conductivity, high strength and strong electromagnetic wave absorption capacity, and can be widely applied in the fields of heat insulation, adsorption, filtration, electromagnetic shielding, catalyst carrier and the like. The technical scheme of the application comprises the following steps: step one, pouring water, carbon powder, silica sol, wetting agent, liquid alkane and emulsifier into a ball mill, and ball milling at a speed of 10-500 r / min for 25-35 min to prepare a mixed slurry; step two, pouring the mixed slurry obtained in the step one into a stirring barrel for continuous stirring, adding a solidifying agent to cross-link and solidify the mixed slurry, and obtaining a viscous slurry; and step three, pouring the viscous slurry obtained in the step two into a mold, and performing solidification and drying in a constant-temperature and constant-humidity box to finally obtain the foam carbon material.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of materials, and particularly relates to a preparation method of high-strength foam carbon material. BACKGROUND

[0002] The porosity and pore size of the foam carbon material have important influences on the performance of the material. The pore structure of the foam carbon prepared by the current preparation method is related to the inherent pore structure of the polymer precursor, is difficult to control, and the size is generally large. The smaller the pore size of the pore, the higher the strength of the material, and the lower the thermal conductivity. In addition, the porosity of the material can be adjusted to widen the application field thereof. Therefore, it is crucial to explore an efficient method for preparing the material with the advantages of high strength, low pore size, adjustable porosity, and the like. The emulsion template method is generally a new method for preparing porous ceramics. By adjusting the water / oil volume ratio, the pore size and porosity of the foam carbon can be easily changed, and the evaporation of the oil droplets to form the pores is realized in the drying and curing process. The current emulsion template method has not been used in carbon materials, because the emulsion method relies on the effect of the emulsifier at the oil-water interface in the emulsification process, and the carbon material needs to have sufficient wettability for dispersion in water, and the wettability process will affect the emulsification effect. How to coordinate the emulsification and wettability effect, that is, how to uniformly emulsify without affecting the dispersion of the carbon to achieve high solid content is actually very difficult. SUMMARY

[0003] The application provides a preparation method of high-strength foam carbon material. The application adopts carbon powder as raw material, and prepares foam carbon by combining the emulsion method with the silica sol gel, so that the material has a pore size of 1-30 mu m and adjustable porosity. The preparation method is simple, easy to operate, low in cost, and non-toxic, and the prepared foam carbon has a wide application prospect in the fields of renewable energy, heat insulation, and wave absorption.

[0004] The application provides a preparation method of high-strength foam carbon material, which comprises the following steps:

[0005] Step one, water, carbon powder, silica sol, wetting agent, liquid alkane and emulsifier are poured into a ball mill, and ball milling is carried out at a speed of 10-500 r / min for 25-35 min to prepare a mixed slurry;

[0006] Step two, the mixed slurry obtained in step one is poured into a stirring barrel for continuous stirring, and a curing agent is added to crosslink and cure the mixed slurry, so that a viscous slurry is obtained;

[0007] Step three, the viscous slurry obtained in step two is poured into a mold, and solidification and drying are carried out in a constant-temperature and constant-humidity box, and finally the foam carbon material is obtained.

[0008] The carbon powder particle size in step one is 0.1-10 mu m, the SiO2 content in the silica sol is 10-30%, the mass ratio of water, carbon powder and silica sol is 0-3:1-9:1, and the C:Si molar ratio in the carbon powder and silica sol is 3:1.

[0009] The liquid alkane in step one has a carbon atom number greater than 5, including n-octane, n-hexane, 2-methylpentane and heptane.

[0010] The addition amount of the liquid alkane is 0.5-8 times the volume of the water in the silica sol, the liquid alkane plays a pore-forming role, and the maximum addition amount is 0.5-8 times, and more will not be able to be formed.

[0011] The emulsifier is Tween 80, and the addition amount is 3-10% of the mass of the carbon powder.

[0012] The wetting agent in step one includes but is not limited to polyether wetting agent, ammonium wetting agent and high molecular dispersant, and the addition amount is 0.2-3% of the mass of the carbon powder.

[0013] The polyether wetting agent includes a fatty alcohol polyoxyethylene ether.

[0014] The ammonium wetting agent includes one or a mixture of several of dodecyl fatty amine, hexadecyl fatty amine and octadecyl fatty amine.

[0015] The high molecular dispersant includes one or a mixture of several of polyacrylic acid sodium salt, polyvinyl alcohol, polyethylene glycol and paraffin.

[0016] The curing agent in step two is NH4Cl, the mass ratio of NH4Cl:H2O is 1:5, and the addition amount is 0.2-2% of the mass of the carbon powder.

[0017] The curing and drying temperature in step three is 30-80 DEG C, and the curing and drying time is 0.1-100 h.

[0018] Compared with the prior art, the present application has the following beneficial effects:

[0019] The present application uses carbon powder as raw material, and prepares a foam carbon with a pore size of 1-30 mu m by a method of emulsion combined with silica sol gel, because the carbon powder particles are attached to form pore walls to form a pore size, therefore the particle size of the carbon powder used is smaller than the pore size, and the carbon powder particle size is 0.1-10 mu m; and the pore size can be adjusted according to the slurry ratio, and the porosity can be controlled according to the oil-water ratio.

[0020] The preparation method of the present application is simple, easy to operate, low in cost and non-toxic.

[0021] The foam carbon material of the present application has low thermal conductivity, high strength and strong electromagnetic wave absorption capacity, and can be widely used in heat insulation, adsorption, filtration, electromagnetic shielding, catalyst carrier and other fields. Attached Figure Description

[0022] Figure 1 SEM image of the foamed carbon prepared in Example 1 of the present invention;

[0023] Figure 2 SEM image of the foamed carbon prepared in Example 2 of the present invention;

[0024] Figure 3 SEM image of the foamed carbon prepared in Example 3 of the present invention;

[0025] Figure 4 SEM image of the foamed carbon prepared in Example 4 of the present invention;

[0026] Figure 5 This is a photograph of the foamed carbon prepared in Example 1 of the present invention. Detailed Implementation

[0027] Example 1:

[0028] Step 1: Pour water, toner, and silica sol into a ball mill at a mass ratio of 0:1:1. At the same time, add 3% Tween 80 (by mass of toner), 0.5 times the volume of water in the silica sol, and 0.2% hexadecyl fatty amine (by mass of toner) into the ball mill. Ball mill at 10 r / min for 25 min to obtain a mixed slurry.

[0029] The C:Si molar ratio in the toner and silica sol is 3:1, the SiO2 content in the silica sol is 10%, and the toner particle size is 0.1μm.

[0030] Step 2: Pour the mixed slurry obtained in Step 1 into a mixing tank and continue stirring. Add NH4Cl, with a mass ratio of NH4Cl to H2O of 1:5, and the amount added accounts for 0.2% of the mass of the toner. This will allow the mixture to crosslink and solidify, resulting in a viscous slurry.

[0031] Step 3: Pour the viscous slurry obtained in Step 2 into a mold and cure and dry it in a constant temperature and humidity chamber at 30°C for 0.1 hours to obtain foamed carbon material.

[0032] The toner used in Example 1 has a particle size of 0.1 μm, and the average pore size obtained is 15 μm.

[0033] Example 2:

[0034] Step one, water, carbon powder and silica sol are poured into the ball mill according to the mass ratio of 1:2:1, at the same time, 5% of the carbon powder quality of Tween 80, 1 times of the volume of water in the silica sol of n-hexane and 1% of the carbon powder quality of sodium polyacrylate are added into the ball mill, and the ball mill is operated at the speed of 100 r / min for 30 min to prepare the mixed slurry.

[0035] The C:Si molar ratio in the carbon powder and the silica sol is 3:1, the SiO2 content in the silica sol is 15%, and the carbon powder particle size is 2 μm.

[0036] Step two, the mixed slurry obtained in step one is poured into the stirring barrel for continuous stirring, NH4Cl is added, the mass ratio of NH4Cl:H2O is 1:5, and the amount of addition is 0.7% of the carbon powder quality, so as to cross-link and solidify, and a viscous slurry is obtained.

[0037] Step three, the viscous slurry obtained in step two is poured into a mold, and solidification and drying are carried out in a constant temperature and humidity box, the solidification and drying temperature is 40℃, the solidification and drying time is 10h, and finally a foamed carbon material is obtained.

[0038] The carbon powder particle size used in this example 2 is 1 μm, and the average pore size obtained is 17 μm.

[0039] Example 3:

[0040] Step one, water, carbon powder and silica sol are poured into the ball mill according to the mass ratio of 2:3:1, at the same time, 6% of the carbon powder quality of Tween 80, 3 times of the volume of water in the silica sol of 2-methylpentane and 2% of the carbon powder quality of dodecyl fatty amine are added into the ball mill, and the ball mill is operated at the speed of 200 r / min for 31 min to prepare the mixed slurry.

[0041] The C:Si molar ratio in the carbon powder and the silica sol is 3:1, the SiO2 content in the silica sol is 20%, and the carbon powder particle size is 5 μm.

[0042] Step two, the mixed slurry obtained in step one is poured into the stirring barrel for continuous stirring, NH4Cl is added, the mass ratio of NH4Cl:H2O is 1:5, and the amount of addition is 1.5% of the carbon powder quality, so as to cross-link and solidify, and a viscous slurry is obtained.

[0043] Step three, the viscous slurry obtained in step two is poured into a mold, and solidification and drying are carried out in a constant temperature and humidity box, the solidification and drying temperature is 70℃, respectively dried at 30℃ for 24h, 50℃ for 24h, 80℃ for 24h, and finally a foamed carbon material is obtained.

[0044] The carbon powder particle size used in this example 3 is 5 μm, and the average pore size obtained is 14 μm.

[0045] Example 4:

[0046] Step one, water, carbon powder and silica sol are poured into a ball mill according to the mass ratio of 3:9:1, and 10% of the mass of the carbon powder, Tween 80, 8 times the volume of the water in the silica sol, and 3% of the mass of the carbon powder are added to the ball mill, and the mixture is ball milled at a speed of 500 r / min for 35 min to obtain a mixed slurry.

[0047] The C:Si molar ratio in the carbon powder and the silica sol is 3:1, the SiO2 content in the silica sol is 30%, and the particle size of the carbon powder is 10 μm.

[0048] Step two, the mixed slurry obtained in step one is poured into a stirring barrel for continuous stirring, and NH4Cl is added, the mass ratio of NH4Cl:H2O is 1:5, and the amount of NH4Cl added is 2% of the mass of the carbon powder, so as to cross-link and solidify, and a viscous slurry is obtained.

[0049] Step three, the viscous slurry obtained in step two is poured into a mold, and solidification and drying are carried out in a constant temperature and humidity box, the solidification and drying temperature is 80℃, the solidification and drying time is 100 h, and finally a foamed carbon material is obtained.

[0050] The carbon powder used in this example 4 has a particle size of 10 μm, and the average pore size obtained is 9 μm.

[0051] The above is only an embodiment of the present application, and does not limit the present application in any form, and the present application can also have other forms of embodiments according to the above structure and function, and does not list them one by one. Therefore, any skilled person in the art, without departing from the scope of the technical solutions of the present application, according to the technical essence of the present application, any simple modification, equivalent change and modification of the above embodiments, still belongs to the scope of the technical solutions of the present application.

Claims

1. A method for preparing a high-strength foamed carbon material, characterized in that: Includes the following steps: Step 1: Pour water, carbon powder, silica sol, wetting agent, liquid alkane and emulsifier into a ball mill and ball mill at a speed of 10-500 r / min for 25-35 min to obtain a mixed slurry; Step 2: Pour the mixed slurry obtained in Step 1 into a mixing tank and continue stirring. Add a curing agent to crosslink and cure the mixture, resulting in a viscous slurry. Step 3: Pour the viscous slurry obtained in Step 2 into a mold, and cure and dry it in a constant temperature and humidity chamber to finally obtain foamed carbon material.

2. The method for preparing a high-strength foamed carbon material according to claim 1, characterized in that: The liquid alkanes in step one have more than 5 carbon atoms, including n-octane, n-hexane, 2-methylpentane, and heptane.

3. A method for preparing a high-strength foamed carbon material according to claim 1 or 2, characterized in that: The amount of liquid alkanes added is 0.5-8 times the volume of water in the silica sol.

4. The method for preparing a high-strength foamed carbon material according to claim 1, characterized in that: The emulsifier is Tween 80, and the amount added accounts for 3-10% of the mass of the toner.

5. The method for preparing a high-strength foamed carbon material according to claim 1, characterized in that: The wetting agent mentioned in step one includes polyether wetting agents, ammonium wetting agents, and polymeric dispersants, and the amount added accounts for 0.2-3% of the mass of the toner.

6. The method for preparing a high-strength foamed carbon material according to claim 5, characterized in that: Polyether wetting agents include fatty alcohol polyoxyethylene ethers.

7. The method for preparing a high-strength foamed carbon material according to claim 5, characterized in that: Ammonium wetting agents include one or a mixture of several of dodecyl fatty amines, hexadecyl fatty amines, and octadecyl fatty amines.

8. The method for preparing a high-strength foamed carbon material according to claim 5, characterized in that: Polymer dispersants include one or a mixture of several of sodium polyacrylate, polyvinyl alcohol, polyethylene glycol, and paraffin.

9. The method for preparing a high-strength foamed carbon material according to claim 1, characterized in that: The curing agent mentioned in step two is NH4Cl, with a mass ratio of NH4Cl to H2O of 1:5, and the amount added accounts for 0.2-2% of the mass of the toner.

10. The method for preparing a high-strength foamed carbon material according to claim 1, characterized in that: The curing and drying temperature in step three is 30-80℃, and the curing and drying time is 0.1-100h.

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