A method for pressureless carbonization of high tensile property dense carbon plate
By controlling the thickness of the wet gel and the deformation of the gel network in a pressureless carbonization process, the problems of insufficient density and tensile properties in pressureless carbonization are solved, and high-performance carbon plates are prepared, which are suitable for aerospace, new energy thermal management and high-end equipment structural components.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HARBIN INST OF TECH
- Filing Date
- 2026-05-26
- Publication Date
- 2026-06-26
AI Technical Summary
Existing technologies make it difficult to produce carbon plates with high density and high tensile properties under pressureless conditions, which limits their application in high-end fields.
High tensile strength dense carbon plates are prepared by controlling the critical thickness of wet gel and combining thermal polymerization, gel network deformation and pre-carbonization processes. This includes preparing glucose and acrylamide solutions, forming wet gels and then carbonizing them under pressureless conditions.
The process achieves complete densification and high tensile properties of carbon plates under pressureless conditions, producing carbon plates with smooth surfaces and continuous structures, possessing excellent mechanical properties, meeting the needs of high-end applications, and with simple and low-cost processes.
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Figure CN122277253A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of carbon-based material preparation technology, and in particular to a pressureless carbonization preparation method for a dense carbon plate with high tensile properties. Background Technology
[0002] Dense carbon plates possess comprehensive advantages such as low density, high modulus, high thermal conductivity, and corrosion resistance. They have irreplaceable application value in fields such as aerospace, new energy thermal management, and high-end equipment structural components. Their completely dense internal structure can ensure the mechanical stability of the material, and the continuous and uniform carbon skeleton can significantly improve thermal conductivity. They can simultaneously achieve structural support and functional bearing, making them a key material for expanding the high-end application scenarios of carbon-based materials.
[0003] Currently, the industrial production of dense carbon sheets mainly falls into two technical routes: pressure carbonization and pressureless carbonization. While pressure carbonization can yield carbon sheets with high density, it suffers from high equipment investment, complex processes, and limitations on forming dimensions due to tooling constraints, making it difficult to achieve large-scale production of large-sized components. Furthermore, uneven stress distribution during carbonization can easily lead to cracking and deformation of the sheets. Pressureless carbonization offers advantages such as low cost, simple process, and flexible forming, effectively avoiding the shortcomings of pressure processes. However, limited by the properties of traditional precursor materials, it generally suffers from uneven shrinkage and low residual carbon content, resulting in carbon sheets with high porosity and discontinuous structures, making them highly susceptible to cracking and breakage, and essentially unable to form a complete material with stable tensile properties. In addition, existing dense carbon preparation technologies such as resin impregnation and biomass carbonization generally suffer from cumbersome steps and poor process controllability, making it difficult to simultaneously achieve a synergistic improvement in carbon sheet density and mechanical properties, thus failing to meet the dual demands of high performance and low-cost large-scale production.
[0004] In summary, existing technologies struggle to produce fully dense carbon plate materials with excellent mechanical properties under pressureless conditions, hindering the widespread application of high-performance carbon plates in high-end fields. Therefore, developing a novel method that is simple, low-cost, and capable of producing high-density, high-tensile-performance carbon plates under pressureless conditions is an urgent need to overcome current technological bottlenecks and fill relevant technological gaps. Summary of the Invention
[0005] The purpose of this invention is to provide a pressureless carbonization preparation method for high tensile strength dense carbon plates, so as to solve the problems existing in the prior art.
[0006] To achieve the above objectives, the present invention provides the following solution: This invention provides a pressureless carbonization preparation method for high tensile strength dense carbon plates, comprising the following steps: (1) Preparation of board stock solution: Dissolve glucose and acrylamide in water, add initiator, crosslinking agent and sodium alginate, disperse evenly to obtain board stock solution; (2) The original liquid of the board is injected into the mold, the thickness of the original liquid layer is controlled to be 1-1.5 mm, and the mixture is heated and polymerized to form a wet gel to obtain a polyacrylamide gel board; (3) Apply a pressure of 2500-3000 Pa to the polyacrylamide gel plate to deform the gel network, and then perform pre-carbonization treatment; (4) The plate after pre-carbonization treatment in step (3) is placed in a vacuum environment and carbonized under pressureless conditions to obtain the high tensile strength dense carbon plate.
[0007] Furthermore, the mass ratio of glucose, acrylamide, and water is 10:1 to 12:100.
[0008] Furthermore, the initiator is ammonium persulfate, and the crosslinking agent is N,N'-methylenebisacrylamide; the mass ratio of the initiator to acrylamide is 1:40-5:40, and the mass ratio of the crosslinking agent to acrylamide is 1:40-5:40.
[0009] Furthermore, the amount of sodium alginate added is 0.1-0.5% of the mass of the original solution used to make the board.
[0010] Furthermore, the temperature of the thermal polymerization is 60-100℃, and the time is 70-100min.
[0011] Furthermore, the pre-carbonization treatment is carried out at a temperature of 220-250℃ for 1-3 hours; the carbonization treatment is carried out at a temperature of 1400-1600℃ for 1-3 hours.
[0012] Furthermore, in the carbonization process, the temperature is increased to the target temperature at a heating rate of 0.2-0.4℃ / min.
[0013] The present invention further provides a high tensile strength dense carbon plate prepared by the above preparation method.
[0014] This invention achieves complete densification and high tensile properties of carbon plates under pressureless conditions by precisely controlling the critical thickness of the wet gel.
[0015] The critical thickness refers to the maximum thickness at which the wet gel obtained after injection molding and thermal polymerization can maintain complete density, without cracking or porosity under pressureless carbonization conditions. When the thickness of the wet gel is below this critical thickness, although densification can be achieved, it is difficult to meet the requirements of macroscopic applications. When the thickness exceeds this critical thickness, the gel network is prone to uneven shrinkage and internal stress concentration during carbonization, which in turn leads to porosity and cracking of the carbon plate, making it impossible to obtain a complete and dense high-performance carbon plate.
[0016] Based on the aforementioned critical thickness characteristics, this invention controls the thickness of the wet gel to near the critical thickness. Through the synergistic regulation of thermal polymerization, moderate deformation of the gel network, and pre-carbonization processes, the macromolecular network and small molecule components within the gel system can fully interact, improving structural uniformity and pyrolysis stability. This enables complete densification after pressureless carbonization, resulting in carbon plates with macroscopic dimensions, high density, and excellent tensile properties. This overcomes the limitation of traditional pressureless carbonization, which can only produce thin, low-performance carbon materials.
[0017] The present invention discloses the following technical effects: This invention optimizes the regularity of the gel network by controlling the precursor structure and carbonization process, thereby suppressing porosity and structural defects at the source and achieving high densification of carbon plates under pressureless conditions. The carbon plates prepared by this invention have a smooth surface, continuous structure, no obvious defects, and excellent mechanical properties. Furthermore, this invention's process leverages the advantages of low cost and flexible molding in pressureless carbonization, eliminating the need for complex pressurization equipment. The process is simple and controllable, overcoming the performance limitations of traditional pressureless carbonization technology. It enables the large-scale production of high-performance carbon plates, meeting the needs of high-end applications in multiple fields, and combining technological innovation with industrial practicality. Attached Figure Description
[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0019] Figure 1 This is a photograph of the polyacrylamide gel plate prepared in Example 1 of the present invention.
[0020] Figure 2 This is a photograph of the pre-carbonized dense plate prepared in Example 1 of the present invention.
[0021] Figure 3 This is a physical image of the carbon plate material prepared in Example 1 of the present invention.
[0022] Figure 4 The image shows the Raman spectrum of the carbon plate material obtained after carbonization at 1400℃ in Example 1 of this invention.
[0023] Figure 5 This is a cross-sectional view of the carbon plate material prepared in Example 1 of the present invention.
[0024] Figure 6 The tensile properties of four batches of carbon plate materials prepared in Example 3 of this invention are shown in the diagram.
[0025] Figure 7 The tensile properties of two batches of carbon plate material prepared in Example 1 of this invention are shown in the diagram.
[0026] Figure 8 The images show the microstructures of the carbon plate materials prepared in Examples 1, 3, 1, and 2; where (a) is Example 1, (b) is Example 3, (c) is Comparative Example 1, and (d) is Comparative Example 2. Detailed Implementation
[0027] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.
[0028] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.
[0029] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.
[0030] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.
[0031] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.
[0032] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.
[0033] Example 1 This embodiment provides a pressureless carbonization method for preparing high tensile strength dense carbon plates, and the preparation steps are as follows: (1) Weigh 10 parts glucose and 4 parts acrylamide, add them to 100 parts deionized water and stir to dissolve; then add 0.1 parts ammonium persulfate as a thermal polymerization initiator, 0.1 parts N,N'-methylenebisacrylamide as a crosslinking agent, and add sodium alginate accounting for 0.5% of the total mass of the board stock solution as an auxiliary gelling agent and thickener. Stir the above mixture thoroughly for 30 minutes, and after ultrasonic dispersion, obtain the board stock solution.
[0034] (2) Inject the original liquid of the board into the mold, control the thickness of the gel original liquid to 1 mm, place it in a 60 ℃ environment for thermal polymerization, keep it at the temperature for 70 min, form a wet gel, and obtain a polyacrylamide gel board.
[0035] (3) Apply 2500 Pa pressure to the polyacrylamide gel plate to deform the gel network appropriately, and then pre-carbonize it at 220 °C for 2 h to obtain a pre-carbonized dense plate.
[0036] (4) Place the pre-carbonized plate into a vacuum furnace and perform high-temperature carbonization under pressureless conditions: heat up to 1400 ℃ at a heating rate of 0.4 ℃ / min, hold for 2 h, and cool with the furnace to obtain a fully dense carbon plate material with high tensile properties.
[0037] The actual image of the polyacrylamide gel plate prepared in Example 1 is shown below. Figure 1 As shown in the image, a physical picture of the pre-carbonized dense board is as follows. Figure 2 As shown, the final product, a physical image of the carbon fiber plate material, is as follows. Figure 3 As shown.
[0038] Figure 4 This is the Raman spectrum of the carbon plate material in Example 1 of the present invention. The Raman spectrum shows a peak at approximately 1350 cm⁻¹. -1 and 1580 cm -1 The presence of distinct D and G peaks at 1350 cm⁻¹ is typical of Raman spectra of amorphous carbon or graphite-like carbon. In the Raman spectra of carbon materials, the peak at 1350 cm⁻¹ is... -1 Peak D at 1580 cm -1 The G peak at 2700 cm⁻¹ is the core characteristic peak. -1The nearby 2D peaks provide important evidence of the degree of graphitization. The D peak corresponds to defects, edge structures, and disordered regions in the carbon lattice, representing a characteristic response of sp³ hybrid carbon and lattice distortion in carbon materials. The G peak originates from the in-plane stretching vibrations of sp² hybrid carbon, directly reflecting the degree of graphitization order in the carbon material. The 2D peak is a two-phonon resonance scattering peak; its intensity and shape further characterize the stacking order of the sp² carbon layers, appearing only in carbon materials with a high degree of graphitization. The figure shows a distinct 2D peak, along with prominent D and G peaks, indicating the presence of a few-layer graphene-amorphous carbon composite structure in the material.
[0039] Cross-sectional view of the carbon plate material prepared in Example 1 is shown below. Figure 5 .
[0040] Example 2 This embodiment provides a pressureless carbonization method for preparing high tensile strength dense carbon plates, and the preparation steps are as follows: (1) Weigh 10 parts glucose and 6 parts acrylamide, add them to 100 parts deionized water and stir to dissolve; then add 0.15 parts ammonium persulfate as a thermal polymerization initiator, 0.15 parts N,N'-methylenebisacrylamide as a crosslinking agent, and add sodium alginate accounting for 0.5% of the total mass of the board stock solution as an auxiliary gelling agent and thickener. Stir the above mixture thoroughly for 30 minutes to form a wet gel, and then disperse it evenly by ultrasonication to obtain the board stock solution.
[0041] (2) Inject the original liquid of the board into the mold, control the thickness of the gel original liquid to be 1.5 mm, place it in a 60 ℃ environment for thermal polymerization, keep it at the temperature for 80 min, and obtain polyacrylamide gel board.
[0042] (3) Apply 3000 Pa pressure to the polyacrylamide gel plate to deform the gel network appropriately, and then pre-carbonize it at 230 °C for 2 h to obtain a pre-carbonized dense plate.
[0043] (4) Place the pre-carbonized plate into a vacuum furnace and perform high-temperature carbonization under pressureless conditions: heat up to 1600 ℃ at a heating rate of 0.3 ℃ / min, hold for 2 h, and cool with the furnace to obtain a fully dense carbon plate material with high tensile properties.
[0044] Example 3 This embodiment provides a pressureless carbonization method for preparing high tensile strength dense carbon plates, and the preparation steps are as follows: (1) Weigh 10 parts glucose and 8 parts acrylamide, add them to 100 parts deionized water and stir to dissolve; then add 0.2 parts ammonium persulfate as a thermal polymerization initiator, 0.2 parts N,N'-methylenebisacrylamide as a crosslinking agent, and add sodium alginate accounting for 0.5% of the total mass of the board stock solution as an auxiliary gelling agent and thickener. Stir the above mixture thoroughly for 30 minutes, and after ultrasonic dispersion, obtain the board stock solution.
[0045] (2) Inject the original liquid of the board into the mold, control the thickness of the gel original liquid to be 1.5 mm, place it in a 60 ℃ environment for thermal polymerization, keep it at the temperature for 100 min, form a wet gel, and obtain a polyacrylamide gel board.
[0046] (3) Apply 3000 Pa pressure to the polyacrylamide gel plate to deform the gel network appropriately, and then pre-carbonize it at 250 °C for 2 h to obtain a pre-carbonized dense plate.
[0047] (4) Place the pre-carbonized plate into a vacuum furnace and perform high-temperature carbonization under pressureless conditions: heat up to 1600 ℃ at a heating rate of 0.25 ℃ / min, hold for 2 h, and cool with the furnace to obtain a fully dense carbon plate material with high tensile properties.
[0048] Figure 6 The tensile properties of four batches of carbon plate materials prepared in Example 3 of this invention are shown in the diagrams (labeled as 1, 2, 3, and 4, respectively).
[0049] Figure 7 The tensile properties of two batches of pre-carbonized dense plates prepared in Example 1 of the present invention are shown in the diagrams (labeled as 1400-1 and 1400-2, respectively).
[0050] Comparative Example 1 The only difference from Example 1 is that the initial thickness of the wet gel after injection molding is controlled to be 2 mm.
[0051] Comparative Example 2 The only difference from Example 1 is that the initial thickness of the wet gel after injection molding is controlled to be 2.5 mm.
[0052] Figure 8 The images show the microstructures of the carbon plate materials prepared in Examples 1, 3, 1, and 2; where (a) is Example 1, (b) is Example 3, (c) is Comparative Example 1, and (d) is Comparative Example 2.
[0053] Carbon materials prepared by conventional pressureless carbonization have a loose structure, numerous pores, and high mechanical brittleness, making it difficult to conduct tensile property tests. The carbon plate material obtained by this invention has a highly dense structure and excellent matrix continuity, which can be successfully tested for tensile properties, further confirming the low porosity and high density structural characteristics of the material.
[0054] This invention effectively mitigates uneven shrinkage and internal stress concentration during carbonization by limiting the critical thickness range of the wet gel precursor, combined with a synergistic process of gel network regularization treatment, mild pre-carbonization, and low-speed heating in the critical pyrolysis range, thus preventing the rapid escape of small molecules and the formation of micropore defects. The resulting carbon plate material has a smooth and intact macroscopic surface, free from cracks, warping, and visible pores, and the plate structure is compact and continuous.
[0055] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.
Claims
1. A method for preparing high-tensile-strength dense carbon plates by pressureless carbonization, characterized in that, Includes the following steps: (1) Preparation of board stock solution: Dissolve glucose and acrylamide in water, add initiator, crosslinking agent and sodium alginate, disperse evenly to obtain board stock solution; (2) The original liquid of the board is injected into the board mold, the thickness of the original liquid layer is controlled to be 1-1.5 mm, and the mixture is heated and polymerized to form a wet gel to obtain a polyacrylamide gel board. (3) Apply a pressure of 2500-3000 Pa to the polyacrylamide gel plate to deform the gel network, and then perform pre-carbonization treatment; (4) The plate after pre-carbonization treatment in step (3) is placed in a vacuum environment and carbonized under pressureless conditions to obtain the high tensile strength dense carbon plate.
2. The pressureless carbonization preparation method according to claim 1, characterized in that, The mass ratio of glucose, acrylamide, and water is 10:1 to 12:
100.
3. The pressureless carbonization preparation method according to claim 1, characterized in that, The initiator is ammonium persulfate, and the crosslinking agent is N,N'-methylenebisacrylamide; the mass ratio of the initiator to acrylamide is 1:40-5:40, and the mass ratio of the crosslinking agent to acrylamide is 1:40-5:
40.
4. The pressureless carbonization preparation method according to claim 1, characterized in that, The amount of sodium alginate added is 0.1-0.5% of the mass of the original solution used to make the board.
5. The pressureless carbonization preparation method according to claim 1, characterized in that, The heating polymerization is carried out at a temperature of 60-100℃ for a time of 70-100 minutes.
6. The pressureless carbonization preparation method according to claim 1, characterized in that, The pre-carbonization treatment is carried out at a temperature of 220-250℃ for 1-3 hours; the carbonization treatment is carried out at a temperature of 1400-1600℃ for 1-3 hours.
7. The pressureless carbonization preparation method according to claim 6, characterized in that, In the carbonization process, the temperature is increased to the target temperature at a heating rate of 0.2-0.4℃ / min.
8. A dense carbon plate with high tensile properties prepared by the preparation method according to any one of claims 1-7.