CN115974520A - Preparation method of short carbon fiber composite material - Google Patents
Preparation method of short carbon fiber composite material Download PDFInfo
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- CN115974520A CN115974520A CN202310069982.9A CN202310069982A CN115974520A CN 115974520 A CN115974520 A CN 115974520A CN 202310069982 A CN202310069982 A CN 202310069982A CN 115974520 A CN115974520 A CN 115974520A
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- 229920000049 Carbon (fiber) Polymers 0.000 title claims abstract description 122
- 239000004917 carbon fiber Substances 0.000 title claims abstract description 122
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 title claims abstract description 78
- 239000002131 composite material Substances 0.000 title claims abstract description 29
- 238000002360 preparation method Methods 0.000 title claims abstract description 11
- 238000001035 drying Methods 0.000 claims abstract description 62
- 239000000243 solution Substances 0.000 claims abstract description 58
- PXIPVTKHYLBLMZ-UHFFFAOYSA-N Sodium azide Chemical compound [Na+].[N-]=[N+]=[N-] PXIPVTKHYLBLMZ-UHFFFAOYSA-N 0.000 claims abstract description 52
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 claims abstract description 39
- 238000005406 washing Methods 0.000 claims abstract description 31
- UIIMBOGNXHQVGW-UHFFFAOYSA-M Sodium bicarbonate Chemical compound [Na+].OC([O-])=O UIIMBOGNXHQVGW-UHFFFAOYSA-M 0.000 claims abstract description 30
- 238000002791 soaking Methods 0.000 claims abstract description 27
- KGBXLFKZBHKPEV-UHFFFAOYSA-N boric acid Chemical compound OB(O)O KGBXLFKZBHKPEV-UHFFFAOYSA-N 0.000 claims abstract description 26
- 239000004327 boric acid Substances 0.000 claims abstract description 26
- 239000002904 solvent Substances 0.000 claims abstract description 16
- 238000010301 surface-oxidation reaction Methods 0.000 claims abstract description 16
- 230000032683 aging Effects 0.000 claims abstract description 15
- 239000007864 aqueous solution Substances 0.000 claims abstract description 15
- 229910000030 sodium bicarbonate Inorganic materials 0.000 claims abstract description 15
- 235000017557 sodium bicarbonate Nutrition 0.000 claims abstract description 15
- 238000001027 hydrothermal synthesis Methods 0.000 claims abstract description 13
- 239000002253 acid Substances 0.000 claims abstract description 4
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 44
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 30
- 239000008367 deionised water Substances 0.000 claims description 29
- 229910021641 deionized water Inorganic materials 0.000 claims description 29
- YMWUJEATGCHHMB-UHFFFAOYSA-N Dichloromethane Chemical compound ClCCl YMWUJEATGCHHMB-UHFFFAOYSA-N 0.000 claims description 27
- 238000002156 mixing Methods 0.000 claims description 27
- 238000003756 stirring Methods 0.000 claims description 27
- 238000006243 chemical reaction Methods 0.000 claims description 26
- 238000010438 heat treatment Methods 0.000 claims description 21
- 229910052582 BN Inorganic materials 0.000 claims description 18
- PZNSFCLAULLKQX-UHFFFAOYSA-N Boron nitride Chemical compound N#B PZNSFCLAULLKQX-UHFFFAOYSA-N 0.000 claims description 18
- TWRXJAOTZQYOKJ-UHFFFAOYSA-L Magnesium chloride Chemical compound [Mg+2].[Cl-].[Cl-] TWRXJAOTZQYOKJ-UHFFFAOYSA-L 0.000 claims description 18
- 239000004964 aerogel Substances 0.000 claims description 16
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 14
- 239000011259 mixed solution Substances 0.000 claims description 14
- BOTDANWDWHJENH-UHFFFAOYSA-N Tetraethyl orthosilicate Chemical compound CCO[Si](OCC)(OCC)OCC BOTDANWDWHJENH-UHFFFAOYSA-N 0.000 claims description 13
- 235000019441 ethanol Nutrition 0.000 claims description 10
- 230000007935 neutral effect Effects 0.000 claims description 10
- 238000007789 sealing Methods 0.000 claims description 10
- ATRRKUHOCOJYRX-UHFFFAOYSA-N Ammonium bicarbonate Chemical compound [NH4+].OC([O-])=O ATRRKUHOCOJYRX-UHFFFAOYSA-N 0.000 claims description 9
- 229910000013 Ammonium bicarbonate Inorganic materials 0.000 claims description 9
- 235000012538 ammonium bicarbonate Nutrition 0.000 claims description 9
- 239000001099 ammonium carbonate Substances 0.000 claims description 9
- 229910001629 magnesium chloride Inorganic materials 0.000 claims description 9
- 230000003647 oxidation Effects 0.000 claims description 9
- 238000007254 oxidation reaction Methods 0.000 claims description 9
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 8
- 238000000034 method Methods 0.000 claims description 8
- 229910017604 nitric acid Inorganic materials 0.000 claims description 8
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 6
- 239000012774 insulation material Substances 0.000 claims description 6
- 239000012629 purifying agent Substances 0.000 claims description 6
- 239000000377 silicon dioxide Substances 0.000 claims description 5
- 235000012239 silicon dioxide Nutrition 0.000 claims description 5
- NEHMKBQYUWJMIP-UHFFFAOYSA-N chloromethane Chemical compound ClC NEHMKBQYUWJMIP-UHFFFAOYSA-N 0.000 claims description 4
- 230000007062 hydrolysis Effects 0.000 claims description 3
- 238000006460 hydrolysis reaction Methods 0.000 claims description 3
- HEDRZPFGACZZDS-UHFFFAOYSA-N Chloroform Chemical compound ClC(Cl)Cl HEDRZPFGACZZDS-UHFFFAOYSA-N 0.000 claims description 2
- 229960001701 chloroform Drugs 0.000 claims description 2
- 150000001721 carbon Chemical class 0.000 abstract description 11
- 239000006185 dispersion Substances 0.000 abstract description 3
- 229910021645 metal ion Inorganic materials 0.000 abstract description 3
- JLVVSXFLKOJNIY-UHFFFAOYSA-N Magnesium ion Chemical compound [Mg+2] JLVVSXFLKOJNIY-UHFFFAOYSA-N 0.000 abstract description 2
- 239000000443 aerosol Substances 0.000 abstract description 2
- 229910001425 magnesium ion Inorganic materials 0.000 abstract description 2
- 230000000052 comparative effect Effects 0.000 description 14
- 239000000463 material Substances 0.000 description 12
- 239000000499 gel Substances 0.000 description 11
- 238000001816 cooling Methods 0.000 description 9
- 230000000694 effects Effects 0.000 description 8
- 239000000835 fiber Substances 0.000 description 7
- 238000012360 testing method Methods 0.000 description 6
- 239000000203 mixture Substances 0.000 description 5
- 239000004965 Silica aerogel Substances 0.000 description 4
- 230000004048 modification Effects 0.000 description 4
- 238000012986 modification Methods 0.000 description 4
- 239000000395 magnesium oxide Substances 0.000 description 3
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 3
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 description 3
- 238000000746 purification Methods 0.000 description 3
- 239000011240 wet gel Substances 0.000 description 3
- YKTSYUJCYHOUJP-UHFFFAOYSA-N [O--].[Al+3].[Al+3].[O-][Si]([O-])([O-])[O-] Chemical compound [O--].[Al+3].[Al+3].[O-][Si]([O-])([O-])[O-] YKTSYUJCYHOUJP-UHFFFAOYSA-N 0.000 description 2
- 238000002048 anodisation reaction Methods 0.000 description 2
- 238000011065 in-situ storage Methods 0.000 description 2
- 238000009413 insulation Methods 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- JMANVNJQNLATNU-UHFFFAOYSA-N oxalonitrile Chemical compound N#CC#N JMANVNJQNLATNU-UHFFFAOYSA-N 0.000 description 2
- 238000004321 preservation Methods 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- 238000005054 agglomeration Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
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- 239000002612 dispersion medium Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 125000005842 heteroatom Chemical group 0.000 description 1
- -1 heteroatom ions Chemical class 0.000 description 1
- 230000003301 hydrolyzing effect Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 239000011810 insulating material Substances 0.000 description 1
- 238000004377 microelectronic Methods 0.000 description 1
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- 239000002245 particle Substances 0.000 description 1
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- 239000011343 solid material Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000011882 ultra-fine particle Substances 0.000 description 1
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- Chemical Or Physical Treatment Of Fibers (AREA)
- Carbon And Carbon Compounds (AREA)
- Inorganic Fibers (AREA)
Abstract
The invention provides a preparation method of a chopped carbon fiber composite material, which comprises the following steps: selecting chopped carbon fibers, purifying at high temperature to remove metal ions in the chopped carbon fibers, then soaking the chopped carbon fibers in an acid solution, carrying out anode surface oxidation treatment in an electrolytic bath, soaking the solution containing magnesium ions, drying, then soaking the chopped carbon fibers in a solution containing boric acid and sodium azide for hydrothermal reaction, taking out, washing and drying to obtain modified carbon fibers, adding the modified carbon fibers into silica sol for uniform dispersion, standing and aging, soaking the modified carbon fibers in a sodium bicarbonate aqueous solution for solvent replacement and drying to obtain the chopped carbon fiber composite material with an aerosol structure.
Description
Technical Field
The invention relates to a preparation method of a chopped carbon fiber composite material, in particular to a chopped carbon fiber silicon dioxide aerogel composite heat-insulating material.
Background
With the progress of science and technology, the fields of military affairs, national defense, solar energy, semiconductors, heat treatment and the like all relate to the use of heat insulation materials, and particularly, the rapid development of solar energy and semiconductors in recent years makes the demands on the heat insulation materials more prominent.
The aerogel is a light nano solid material which is formed by mutually gathering nano-scale ultrafine particles to form a nano porous network structure and is filled with gaseous dispersion media in network pores. It exhibits excellent thermal insulation, heat preservation, flame retardancy, and excellent chemical stability. Has wide application potential in the aspects of thermal, acoustic, optical, microelectronic, particle detection and the like.
However, silica aerogel materials have defects in the materials themselves due to the large surface tension during the drying process, and the low density, which results in low inherent strength, high brittleness, easy cracking and the like of the silica aerogel materials, limits the practical use thereof.
Chinese application publication CN110282947A discloses a high-strength composite aerogel thermal insulation material, which adopts carbon nitride fibers and aluminum silicate fibers to modify together, so as to improve the mechanical properties and thermal insulation performance of silica aerogel to a certain extent, but the comprehensive properties of the silica aerogel can not reach the satisfactory degree of wider industrial application.
Disclosure of Invention
The invention provides a preparation method of a chopped carbon fiber composite material, which comprises the following steps: the preparation method comprises the steps of selecting chopped carbon fibers, purifying at high temperature to remove metal ions in the chopped carbon fibers, then soaking the chopped carbon fibers in an acid solution, carrying out anode surface oxidation treatment in an electrolytic bath, soaking the solution containing magnesium ions, drying, then soaking the solution containing boric acid and sodium azide for hydrothermal reaction, taking out, washing and drying to obtain modified carbon fibers, adding the modified carbon fibers into silica sol for uniform dispersion, standing and aging, then soaking the modified carbon fibers in a sodium bicarbonate aqueous solution for solvent replacement and drying to obtain the chopped carbon fiber composite material with an aerosol structure.
The preparation method of the short carbon fiber composite material is characterized by comprising the following specific preparation steps:
1) Selecting short carbon fibers, placing the short carbon fibers in a heating furnace, introducing a purifying agent, and heating and purifying in a closed manner;
2) Soaking the purified chopped carbon fibers into an acid solution, and carrying out anodic surface oxidation treatment in an electrolytic bath; soaking the treated carbon fiber into a magnesium chloride solution, adding ammonium bicarbonate, stirring, taking out and drying;
3) Immersing the carbon fiber obtained in the step 2) into a solution containing boric acid and sodium azide for hydrothermal reaction, taking out, washing and drying at high temperature to obtain modified carbon fiber;
4) Tetraethyl orthosilicate, absolute ethyl alcohol and deionized water are mixed, and hydrochloric acid solution is added for hydrolysis to prepare silicon dioxide sol;
5) Mixing the modified carbon fiber obtained in the step (3) with the silica sol, standing and aging, and then soaking in a sodium bicarbonate aqueous solution for solvent replacement; and drying, washing and drying the replaced gel to obtain the chopped carbon fiber composite material.
Further, in the step 1), short carbon fibers with the length of 1-10mm are selected, the short carbon fibers are placed in a heating furnace, a purifying agent is introduced, the purifying agent is selected from one or more of monochloromethane, dichloromethane and trichloromethane, the short carbon fibers are hermetically heated for 4-6 hours at the temperature of 800-1000 ℃, cooled to room temperature, washed and dried, and the purified short carbon fibers are obtained.
Further, the step 2) is as follows: immersing the purified chopped carbon fibers into a nitric acid solution with the mass fraction of 50-60%, carrying out anodic surface oxidation treatment in an electrolytic cell, wherein the oxidation voltage is 4-5V, the treatment time is 10-30min, taking out the chopped carbon fibers after the anodic surface oxidation treatment is finished, immersing the chopped carbon fibers into a magnesium chloride solution containing 1-2wt%, dropwise adding ammonium bicarbonate to adjust the pH value of the solution to be about 8, stirring, taking out and drying.
Further, step 3) is as follows: preparing solutions respectively containing boric acid and sodium azide, and mixing the solutions according to the molar ratio of the boric acid to the sodium azide being 1; and (3) placing the carbon fiber obtained in the step (2) into the mixed solution, then sealing the reaction kettle, placing the reaction kettle into a constant-temperature hydrothermal reaction at 350-400 ℃ for 15-20h to obtain the carbon fiber with boron nitride grains on the surface, washing, and drying at 250-300 ℃ for 10-15h to obtain the modified carbon fiber.
Further, the step 4) is as follows: tetraethyl orthosilicate, absolute ethyl alcohol and deionized water are mixed according to the mass ratio of 8-10.
Further, step 5) is as follows: mixing the modified carbon fiber obtained in the step (3) with the silica sol, wherein the addition amount of the modified carbon fiber is 5-20wt% of the silica sol, uniformly stirring, adjusting the pH to be neutral, standing, adding ethanol with the same mass as the silica sol, standing, aging, and then soaking in 1-1.5mol/L sodium bicarbonate aqueous solution for solvent replacement until the reaction is complete; and drying, washing and drying the replaced gel to obtain the aerogel, namely the chopped carbon fiber composite material.
Further, the chopped carbon fiber composite material is an aerogel thermal insulation material and is prepared by the method.
The invention has the beneficial technical effects
1) Boron nitride is generated in situ through a hydrothermal reaction, and is heated, dried and cured, so that the branched structure on the surface of the carbon fiber is increased, the combination degree of the carbon fiber and silicon dioxide gel is improved, the strength of the chopped fiber is improved through the modification of the boron nitride, and the mechanical property of the material is improved;
2) The boron nitride is subjected to electrolytic treatment before the electrolytic treatment, so that polar groups on the surface of the carbon fiber are increased, the adhesion effect of the boron nitride on the surface of the carbon fiber is improved, and the boron nitride is purified before the electrolytic treatment, so that the content of heteroatom metal ions in the carbon fiber is reduced, and the side reaction of the metal heteroatom ions in the electrolytic process is avoided;
3) The inventor finds that magnesium oxide is formed by in-situ hydrolysis on the surface of the electrolyzed chopped fiber, the dispersion performance of the chopped fiber in silica sol is improved, agglomeration is avoided, the mechanical property is favorably improved, and the carbon fiber modified by magnesium oxide has a lower thermal conductivity.
Detailed Description
The present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to these examples within the scope not exceeding the gist thereof.
Since the mechanical properties and thermal conductivity of the product are significantly affected by the length of the carbon fibers and the ratio of the carbon fibers to the silica sol, only carbon fibers having a length of 5mm are used in the examples and comparative examples of the present application, and the modified carbon fibers are added in an amount of 10wt% of the silica sol to compare the effects of the different treatment steps on the properties of the product, but the above parameters should not be construed as limiting the present invention, and it is well within the ability of those skilled in the art to practice the present invention in other ranges of parameters.
Example 1
1) Selecting short carbon fibers with the length of 5 mm; placing the mixture in a heating furnace, introducing dichloromethane, heating the mixture to 800 ℃ in a sealed manner, preserving heat for 6 hours, naturally cooling the mixture to room temperature, washing the mixture for 5 times by using deionized water, and drying the mixture to obtain purified short carbon fibers;
2) Immersing the purified chopped carbon fibers into a nitric acid solution with the mass fraction of 50%, carrying out anodic surface oxidation treatment in an electrolytic cell, wherein the oxidation voltage is 5V, the treatment time is 15min, taking out, immersing into a magnesium chloride solution with the concentration of 1.5wt%, dropwise adding an ammonium bicarbonate solution to adjust the pH value of the solution to be 8, stirring for 1h, taking out and drying;
3) Respectively preparing solutions containing boric acid and sodium azide, wherein the concentrations of the boric acid and the sodium azide are respectively 0.02mol/L, and mixing and uniformly stirring the solutions of the boric acid and the sodium azide to obtain a mixed solution; placing the carbon fiber obtained in the step 2 into the mixed solution, then sealing the reaction kettle, placing the reaction kettle at a constant temperature of 350 ℃ for hydrothermal reaction for 20 hours to obtain carbon fiber with boron nitride grains on the surface, washing, and drying at a constant temperature of 250 ℃ for 15 hours to obtain modified carbon fiber;
4) Mixing tetraethyl orthosilicate, absolute ethyl alcohol and deionized water according to a mass ratio of 1;
5) Mixing the modified carbon fiber obtained in the step 3 and the silica sol obtained in the step 4, wherein the addition amount of the modified carbon fiber is 10wt% of the silica sol, uniformly stirring, adjusting the pH to be neutral, standing, adding ethanol with the same mass as the silica sol, standing, aging, and then soaking in 1mol/L sodium bicarbonate aqueous solution for solvent replacement until the reaction is complete; and drying the replaced gel, washing with deionized water, and drying to obtain the aerogel, namely the chopped carbon fiber composite material.
Example 2
1) Selecting short carbon fibers with the length of 5 mm; placing in a heating furnace, introducing dichloromethane, heating to 800 ℃ in a sealed manner, preserving heat for 6h, naturally cooling to room temperature, washing with deionized water for 5 times, and drying to obtain purified short carbon fibers;
2) Immersing the purified chopped carbon fibers into a nitric acid solution with the mass fraction of 60%, carrying out anodic surface oxidation treatment in an electrolytic cell, wherein the oxidation voltage is 4V, the treatment time is 30min, taking out the chopped carbon fibers after the anodic surface oxidation treatment is finished, immersing the chopped carbon fibers into a magnesium chloride solution with the concentration of 1.5wt%, dropwise adding an ammonium bicarbonate solution to adjust the pH value of the solution to be 8, stirring, taking out and drying;
3) Respectively preparing solutions containing boric acid and sodium azide, wherein the concentrations of the boric acid and the sodium azide are respectively 0.02mol/L, and mixing and uniformly stirring the solutions of the boric acid and the sodium azide to obtain a mixed solution; placing the carbon fiber obtained in the step 2 into the mixed solution, then sealing the reaction kettle, placing the reaction kettle at a constant temperature of 400 ℃ for hydrothermal reaction for 15 hours to obtain carbon fiber with boron nitride grains on the surface, washing, and drying at a constant temperature of 300 ℃ for 10 hours to obtain modified carbon fiber;
4) Mixing tetraethyl orthosilicate, absolute ethyl alcohol and deionized water according to a mass ratio of 1;
5) Mixing the modified carbon fiber obtained in the step 3 and the silica sol obtained in the step 4, wherein the addition amount of the modified carbon fiber is 10wt% of the silica sol, uniformly stirring, adjusting the pH to be neutral, standing, then adding ethanol with the same mass as the silica sol, standing, aging, and then soaking in 1.5mol/L sodium bicarbonate aqueous solution for solvent replacement until the reaction is complete; and drying the gel after replacement, washing with deionized water, and drying to obtain the aerogel, namely the chopped carbon fiber composite material.
Example 3
1) Selecting short carbon fibers with the length of 5 mm; placing in a heating furnace, introducing dichloromethane, heating to 800 ℃ in a sealed manner, preserving heat for 6h, naturally cooling to room temperature, washing with deionized water for 5 times, and drying to obtain purified short carbon fibers;
2) Immersing the purified chopped carbon fibers into a nitric acid solution with the mass fraction of 55%, carrying out anodic surface oxidation treatment in an electrolytic cell, wherein the oxidation voltage is 4.5V, the treatment time is 20min, taking out the chopped carbon fibers after the anodic surface oxidation treatment is finished, immersing the chopped carbon fibers into a magnesium chloride solution with the concentration of 1.5wt%, dropwise adding an ammonium bicarbonate solution to adjust the pH value of the solution to be 8, stirring, taking out and drying;
3) Respectively preparing solutions containing boric acid and sodium azide, wherein the concentrations of the boric acid and the sodium azide are respectively 0.02mol/L, and mixing and uniformly stirring the solutions of the boric acid and the sodium azide to obtain a mixed solution; placing the carbon fiber obtained in the step 2 into the mixed solution, then sealing the reaction kettle, placing the reaction kettle at a constant temperature of 400 ℃ for hydrothermal reaction for 20 hours to obtain carbon fiber with boron nitride grains on the surface, washing, and drying at a constant temperature of 300 ℃ for 15 hours to obtain modified carbon fiber;
4) Tetraethyl orthosilicate, absolute ethyl alcohol and deionized water are mixed according to the mass ratio of 1;
5) Mixing the modified carbon fiber obtained in the step (3) and the silica sol obtained in the step (4), wherein the addition amount of the modified carbon fiber is 10wt% of the silica sol, uniformly stirring, adjusting the pH to be neutral, standing, then adding ethanol with the same mass as the silica sol, standing, aging, and then soaking in 1.5mol/L sodium bicarbonate aqueous solution for solvent replacement until the reaction is complete; and drying the replaced gel, washing with deionized water, and drying to obtain the aerogel, namely the chopped carbon fiber composite material.
Comparative example 1
(1) At room temperature, tetraethyl orthosilicate, absolute ethanol and deionized water were mixed in a molar ratio of 1: 4, mixing, stirring for 2.5h, then adding a hydrochloric acid solution to adjust the pH value to be about 3, and hydrolyzing at 50 ℃ to obtain silicon dioxide sol;
(2) Taking 60 parts of the silica sol prepared in the step (1), adding 3 parts of carbon nitride fibers with the length of 5mm and 3 parts of aluminum silicate fibers with the length of 5mm, adjusting the pH value to be about 7, uniformly dispersing by ultrasonic stirring, and sealing and standing the silica sol to obtain a composite wet gel;
(3) Adding 50 parts of absolute ethyl alcohol into the composite wet gel obtained in the step (2), sealing, placing in a water bath kettle at 20 ℃, standing, aging for 24 hours, and then soaking in a sodium bicarbonate aqueous solution of 0.12g/mL for solvent replacement for 12 hours;
(4) And taking out the composite wet gel after solvent replacement, drying at 70 ℃ for 12min, cleaning with deionized water, and drying at 120 ℃ for 12h to obtain the high-strength composite aerogel thermal insulation material.
Comparative example 2
1) Selecting short carbon fibers with the length of 5 mm; placing in a heating furnace, introducing dichloromethane, heating to 800 ℃ in a sealed manner, preserving heat for 6h, naturally cooling to room temperature, washing with deionized water for 5 times, and drying to obtain purified short carbon fibers;
2) Respectively preparing solutions containing boric acid and sodium azide, wherein the concentrations of the boric acid and the sodium azide are respectively 0.02mol/L, and mixing and uniformly stirring the solutions of the boric acid and the sodium azide to obtain a mixed solution; placing the carbon fiber obtained in the step 1 into the mixed solution, then sealing the reaction kettle, placing the reaction kettle at a constant temperature of 400 ℃ for hydrothermal reaction for 20 hours to obtain carbon fiber with boron nitride grains on the surface, washing, and drying at a constant temperature of 300 ℃ for 15 hours to obtain modified carbon fiber;
3) Mixing tetraethyl orthosilicate, absolute ethyl alcohol and deionized water according to a mass ratio of 1;
4) Mixing modified carbon fiber and silica sol, wherein the addition amount of the modified carbon fiber is 10wt% of the silica sol, uniformly stirring, adjusting the pH value to be neutral, standing, adding ethanol with the same mass as the silica sol, standing, aging, and then soaking in 1.5mol/L sodium bicarbonate aqueous solution for solvent replacement until the reaction is complete; and drying the replaced gel, washing with deionized water, and drying to obtain the aerogel, namely the chopped carbon fiber composite material.
Comparative example 3
1) Soaking short carbon fibers with the length of 5mm into a nitric acid solution with the mass fraction of 55%, carrying out anode surface oxidation treatment in an electrolytic bath, wherein the oxidation voltage is 4.5V, the treatment time is 20min, taking out after the treatment, soaking the short carbon fibers into a magnesium chloride solution with the concentration of 1.5wt%, dropwise adding an ammonium bicarbonate solution to adjust the pH value of the solution to be 8, stirring, taking out and drying;
2) Respectively preparing solutions containing boric acid and sodium azide, wherein the concentrations of the boric acid and the sodium azide are respectively 0.02mol/L, and mixing and uniformly stirring the solutions of the boric acid and the sodium azide to obtain a mixed solution; placing the carbon fiber obtained in the step 2 into the mixed solution, then sealing the reaction kettle, placing the reaction kettle at a constant temperature of 400 ℃ for hydrothermal reaction for 20 hours to obtain carbon fiber with boron nitride grains on the surface, washing, and drying at a constant temperature of 300 ℃ for 15 hours to obtain modified carbon fiber;
3) Mixing tetraethyl orthosilicate, absolute ethyl alcohol and deionized water according to a mass ratio of 1;
4) Mixing modified carbon fibers and silica sol, wherein the addition amount of the modified carbon fibers is 10wt% of the silica sol, uniformly stirring, adjusting the pH value to be neutral, standing, adding ethanol with the same mass as the silica sol, standing, aging, and then soaking in 1.5mol/L sodium bicarbonate aqueous solution for solvent replacement until the reaction is complete; and drying the replaced gel, washing with deionized water, and drying to obtain the aerogel, namely the chopped carbon fiber composite material.
Comparative example 4
1) Selecting short carbon fibers with the length of 5 mm; placing in a heating furnace, introducing dichloromethane, heating to 800 ℃ in a sealed manner, preserving heat for 6h, naturally cooling to room temperature, washing with deionized water for 5 times, and drying to obtain purified short carbon fibers;
2) Immersing the purified chopped carbon fibers into a nitric acid solution with the mass fraction of 55%, carrying out anode surface oxidation treatment in an electrolytic bath, wherein the oxidation voltage is 4.5V, the treatment time is 20min, and taking out and drying after the treatment is finished;
3) Respectively preparing solutions containing boric acid and sodium azide, wherein the concentrations of the boric acid and the sodium azide are respectively 0.02mol/L, and mixing and uniformly stirring the solutions of the boric acid and the sodium azide to obtain a mixed solution; placing the carbon fiber obtained in the step 2 into the mixed solution, then sealing the reaction kettle, placing the reaction kettle at a constant temperature of 400 ℃ for hydrothermal reaction for 20 hours to obtain carbon fiber with boron nitride grains on the surface, washing, and drying at a constant temperature of 300 ℃ for 15 hours to obtain modified carbon fiber;
4) Tetraethyl orthosilicate, absolute ethyl alcohol and deionized water are mixed according to the mass ratio of 1;
5) Mixing the modified carbon fiber obtained in the step 3 and the silica sol obtained in the step 4, wherein the addition amount of the modified carbon fiber is 10wt% of the silica sol, uniformly stirring, adjusting the pH to be neutral, standing, then adding ethanol with the same mass as the silica sol, standing, aging, and then soaking in 1.5mol/L sodium bicarbonate aqueous solution for solvent replacement until the reaction is complete; and drying the replaced gel, washing with deionized water, and drying to obtain the aerogel, namely the chopped carbon fiber composite material.
Comparative example 5
1) Selecting short carbon fibers with the length of 5 mm; placing in a heating furnace, introducing dichloromethane, heating to 800 ℃ in a sealed manner, preserving heat for 6h, naturally cooling to room temperature, washing with deionized water for 5 times, and drying to obtain purified short carbon fibers;
2) Immersing the purified chopped carbon fibers into a nitric acid solution with the mass fraction of 55%, carrying out anodic surface oxidation treatment in an electrolytic cell, wherein the oxidation voltage is 4.5V, the treatment time is 20min, taking out the chopped carbon fibers after the treatment, immersing the chopped carbon fibers into a magnesium chloride solution with the concentration of 1.5wt%, dropwise adding an ammonium bicarbonate solution to adjust the pH value of the solution to be 8, stirring, taking out and drying;
3) Mixing tetraethyl orthosilicate, absolute ethyl alcohol and deionized water according to a mass ratio of 1;
4) Mixing carbon fibers and silica sol, wherein the addition amount of the modified carbon fibers is 10wt% of the silica sol, uniformly stirring, adjusting the pH value to be neutral, standing, adding ethanol with the same mass as the silica sol, standing, aging, and then soaking in 1.5mol/L sodium bicarbonate aqueous solution for solvent replacement until the reaction is complete; and drying the replaced gel, washing with deionized water, and drying to obtain the aerogel, namely the chopped carbon fiber composite material.
Comparative example 6
1) Selecting short carbon fibers with the length of 5 mm; placing in a heating furnace, introducing dichloromethane, heating to 800 ℃ in a sealed manner, preserving heat for 6h, naturally cooling to room temperature, washing with deionized water for 5 times, and drying to obtain purified short carbon fibers;
2) Mixing tetraethyl orthosilicate, absolute ethyl alcohol and deionized water according to a mass ratio of 1;
3) Mixing carbon fibers and the silica sol, wherein the addition amount of the modified carbon fibers is 10wt% of the silica sol, uniformly stirring, adjusting the pH value to be neutral, standing, adding ethanol with the same mass as the silica sol, standing, aging, and then soaking in 1.5mol/L sodium bicarbonate aqueous solution for solvent replacement until the reaction is complete; and drying the replaced gel, washing with deionized water, and drying to obtain the aerogel, namely the chopped carbon fiber composite material.
Experiments and data
The material of the invention was tested for its properties using the following test conditions, wherein comparative example 1 is a product disclosed in the background art CN 110282947A.
Compressive strength
Drying a carbon fiber sample with the size of 80mm multiplied by 20mm to constant weight, cooling to room temperature, placing the sample on a pressure bearing plate of a testing machine, enabling the center of the pressure bearing plate of the testing machine to coincide with the center of the sample, starting the testing machine, and adjusting a ball seat when an upper pressure plate is close to the sample to enable the pressure surface of the sample to be in uniform contact with the pressure bearing plate; the sample was loaded at a rate of 10mm/min until the sample was destroyed and the compression set value was recorded. When the specimen was not broken at 5% compressive deformation, the load at 5% compressive deformation of the specimen was the breaking load recorded breaking load P1. The compressive strength calculation formula is as follows:
A＝P1/S；
in the formula: a is the compressive strength of the sample, MPa; p1 is the breaking load of the sample, N; s is the pressed area of the sample, mm 2 ；
Heat conductivity
And (3) drying a carbon fiber heat-preservation cylinder sample with the size of 80mm multiplied by 20mm to constant weight, cooling to room temperature, and placing the sample in an intelligent double-plate heat conductivity coefficient tester to test the heat conductivity coefficient of the sample at room temperature. The test results are shown in table 1 below:
TABLE 1
As can be seen from the comparison of the data of examples 1 to 3 and from comparative example 1, the material of the invention has higher mechanical properties and a lower thermal conductivity; the data of the comparative example 2 show that the anodic oxidation modification before the boron nitride is compounded can improve the adhesion degree of the boron nitride, and has great influence on the mechanical properties of the material; the data of comparative example 3 show that the purification process has an important effect on the reduction of the thermal conductivity while affecting the mechanical properties of the material, probably because the unpurified metal impurities generate oxides in the preparation process or affect the adhesion of boron nitride, thereby having a negative effect on the properties of the material; based on comparative example 4, it can be seen that the modification of magnesium oxide has a very significant effect on the improvement of the mechanical properties of the material and the reduction of the thermal conductivity; as can be seen in comparative examples 5 and 6, the modification of boron nitride has a large effect on the material, while the purification and anodization steps mainly affect the boron nitride combination step, while the purification and anodization steps alone have little effect on the material.
While the present invention has been described in detail with reference to the preferred embodiments, it should be understood that the above description should not be taken as limiting the invention.
Claims (7)
1. The preparation method of the chopped carbon fiber composite material is characterized by comprising the following specific preparation steps:
1) Selecting short carbon fibers, placing the short carbon fibers in a heating furnace, introducing a purifying agent, and heating and purifying in a closed manner;
2) Soaking the purified chopped carbon fibers into an acid solution, and carrying out anodic surface oxidation treatment in an electrolytic cell; soaking the treated carbon fiber into a magnesium chloride solution, adding ammonium bicarbonate, stirring, taking out and drying;
3) Immersing the carbon fiber obtained in the step 2) into a solution containing boric acid and sodium azide for hydrothermal reaction, taking out, washing and drying at high temperature to obtain modified carbon fiber;
4) Tetraethyl orthosilicate, absolute ethyl alcohol and deionized water are mixed, and hydrochloric acid solution is added for hydrolysis to prepare silicon dioxide sol;
5) Mixing the modified carbon fiber obtained in the step (3) with the silica sol, standing and aging, and then soaking in a sodium bicarbonate aqueous solution for solvent replacement; and drying, washing and drying the replaced gel to obtain the chopped carbon fiber composite material.
2. The method according to claim 1, wherein the short carbon fibers with the length of 1-10mm are selected in the step 1), the short carbon fibers are placed in a heating furnace, a purifying agent is introduced, the purifying agent is selected from one or more of monochloromethane, dichloromethane and trichloromethane, the short carbon fibers are heated in a sealed manner at 800-1000 ℃ for 4-6h, cooled to room temperature, washed and dried, and the purified short carbon fibers are obtained.
3. The method of claim 1, wherein step 2) comprises: immersing the purified chopped carbon fibers into a nitric acid solution with the mass fraction of 50-60%, carrying out anodic surface oxidation treatment in an electrolytic cell, wherein the oxidation voltage is 4-5V, the treatment time is 10-30min, taking out the chopped carbon fibers after the anodic surface oxidation treatment is finished, immersing the chopped carbon fibers into a magnesium chloride solution containing 1-2wt%, dropwise adding ammonium bicarbonate to adjust the pH value of the solution to be about 8, stirring, taking out and drying.
4. The method of claim 1, wherein step 3) is: preparing solutions respectively containing boric acid and sodium azide, mixing the solutions according to the molar ratio of boric acid to sodium azide of 1; and (3) placing the carbon fiber obtained in the step (2) into the mixed solution, then sealing the reaction kettle, placing the reaction kettle into a constant-temperature hydrothermal reaction at 350-400 ℃ for 15-20h to obtain the carbon fiber with boron nitride grains on the surface, washing, and drying at 250-300 ℃ for 10-15h to obtain the modified carbon fiber.
5. The method of claim 1, wherein step 4) is: tetraethyl orthosilicate, absolute ethyl alcohol and deionized water are mixed according to the mass ratio of 8-10.
6. The method of claim 1, wherein step 5) is: mixing the modified carbon fiber obtained in the step (3) with the silica sol, wherein the addition amount of the modified carbon fiber is 5-20wt% of the silica sol, uniformly stirring, adjusting the pH to be neutral, standing, adding ethanol with the same mass as the silica sol, standing, aging, and then soaking in 1-1.5mol/L sodium bicarbonate aqueous solution for solvent replacement until the reaction is complete; and drying, washing and drying the replaced gel to obtain the aerogel, namely the chopped carbon fiber composite material.
7. A chopped carbon fiber composite material which is an aerogel thermal insulation material, characterized in that it is prepared by the method of any one of claims 1 to 6.
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| US3351484A (en) * | 1963-11-14 | 1967-11-07 | Hitco | Carbon fibers and method |
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| CN103588989A (en) * | 2013-11-01 | 2014-02-19 | 华东理工大学 | Method for recovery of carbon fiber by use of low temperature molten salt |
| CN107326655A (en) * | 2017-07-11 | 2017-11-07 | 湖南金戈新材料有限责任公司 | A kind of method of carbon fiber surface modification |
| CN110282947A (en) * | 2019-06-13 | 2019-09-27 | 深圳诺必达节能环保有限公司 | A kind of high-strength composite aeroge thermal insulation material and preparation method thereof |
| CN113981697A (en) * | 2021-12-15 | 2022-01-28 | 四川大学 | Carbon fiber surface interface modification method and modified carbon fiber thereof |
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| US3351484A (en) * | 1963-11-14 | 1967-11-07 | Hitco | Carbon fibers and method |
| JP2009114557A (en) * | 2007-11-02 | 2009-05-28 | Toho Tenax Co Ltd | Uniformly surface-treated carbon fiber and method for producing the same |
| CN103588989A (en) * | 2013-11-01 | 2014-02-19 | 华东理工大学 | Method for recovery of carbon fiber by use of low temperature molten salt |
| CN107326655A (en) * | 2017-07-11 | 2017-11-07 | 湖南金戈新材料有限责任公司 | A kind of method of carbon fiber surface modification |
| CN110282947A (en) * | 2019-06-13 | 2019-09-27 | 深圳诺必达节能环保有限公司 | A kind of high-strength composite aeroge thermal insulation material and preparation method thereof |
| CN113981697A (en) * | 2021-12-15 | 2022-01-28 | 四川大学 | Carbon fiber surface interface modification method and modified carbon fiber thereof |
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