Disordered mesoporous carbon for preparing carbon / carbon composite material and preparation method thereof

Abstract

The present application relates to a kind of disordered mesoporous carbon preparation carbon / carbon composite material and its preparation method, the carbon / carbon composite material is obtained by the composite powder of mesoporous carbon, diamond and carbon fiber mixing is prepared by pressure sintering.The present application utilizes the high sintering activity of mesoporous carbon and the phase transition auxiliary self-pressurization sintering effect of diamond to realize the low-temperature sintering preparation carbon / carbon composite material, compared with traditional carbon / carbon composite material preparation technology, the preparation method of the present application has the advantages such as low preparation temperature, short cycle, low energy consumption, and the composite material also has good mechanical properties.

Description

Technical Field

[0001] This invention belongs to the field of structural engineering, and specifically relates to a method for preparing carbon / carbon composite materials from disordered mesoporous carbon. Background Technology

[0002] Carbon / carbon (C / C) composites are strategic high-tech materials that use carbon fibers as reinforcement embedded in a carbon matrix. These composites exhibit outstanding comprehensive performance, particularly their unique strength characteristics: at high temperatures, their strength and modulus not only do not decrease but actually increase with temperature, while also possessing high fracture toughness and low creep rate. Furthermore, C / C composites possess a series of excellent physical properties, including low density, low coefficient of thermal expansion, excellent thermal shock resistance, and ablation resistance. These properties enable them to maintain good creep resistance and high strength retention over a wide temperature range. Notably, carbon / carbon composites are currently the only known materials that can maintain structural integrity at extreme temperatures above 3000 °C, with a theoretical upper limit of 3500 °C. Based on these unique and superior performance combinations, carbon / carbon composites have been widely used in key fields such as aerospace, defense, high-end industries (e.g., automotive braking systems, thermal components), photovoltaics, and semiconductor manufacturing.

[0003] Currently, the main methods for preparing carbon / carbon composite materials include chemical vapor deposition (CVD) / infiltration (CVI), liquid phase impregnation, and preform molding. CVD and CVI involve introducing hydrocarbon gases (such as methane, propane, and natural gas) into a reactor containing a preform under high temperature and low pressure. The gases undergo pyrolysis on the inner surface of the preform's pores or the surface of its fibers, depositing a pyrolytic carbon (PyC) matrix. The resulting composite matrix has high purity and controllable structure, enabling the fabrication of complex shapes, and the process is relatively clean. However, it suffers from drawbacks such as extremely long production cycles, high costs, and closed pores. Liquid phase impregnation involves immersing the preform in a liquid carbon precursor (such as thermosetting resins: phenolic, furan, or asphalt), impregnating the pores under pressure or vacuum, then curing the resin or coking asphalt, and finally carbonizing at high temperature (>1000 °C) in an inert atmosphere to convert the organic matter into a carbon matrix. This process typically requires multiple impregnation-carbonization cycles. Its advantages include simple equipment and excellent densification effect, but it suffers from easy shrinkage and cracking, affecting mechanical properties. Furthermore, the raw material has a low carbon yield, and the processing generates waste gas, causing environmental pollution. Preform molding involves forming carbon fibers into a skeleton structure (preform) with the desired shape and fiber orientation through weaving (2D, 2.5D, 3D, multi-dimensional weaving), needle punching, winding, and lamination. 3D weaving can significantly improve the interlaminar strength and ablation resistance of materials; however, the weaving technology determines the anisotropy and upper limit of mechanical properties of the material, and complex 3D weaving techniques are difficult and costly.

[0004] Carbon / carbon composites, with their ultra-high high-temperature strength retention, excellent thermophysical properties, and lightweight characteristics, play an irreplaceable role in extreme and harsh environments such as high-temperature thermal structural components in aerospace and high-performance braking systems. However, their complex preparation process and long preparation cycle significantly increase their manufacturing costs, greatly limiting their wider application.

[0005] Therefore, how to achieve a simple and convenient preparation process for carbon / carbon composite materials while ensuring that the strength of the composite materials remains at a high level is a key problem that researchers in this field still need to solve. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a method for preparing carbon / carbon composite materials from disordered mesoporous carbon, so as to achieve simple and convenient preparation of carbon / carbon composite materials with high strength.

[0007] This invention provides a carbon / carbon composite material prepared from disordered mesoporous carbon, which is obtained by pressure sintering of composite powder obtained by mixing mesoporous carbon, diamond and carbon fiber.

[0008] Preferably, the composite powder contains 30-90% mesoporous carbon, 5-30% diamond, and 5-40% carbon fiber by mass fraction.

[0009] Preferably, the mesoporous carbon has a pore size of 4~50 nm, the diamond has a particle size of 10 nm~10 μm, and the carbon fiber has a length of 10~500 μm.

[0010] The present invention also provides a method for preparing the above-mentioned carbon / carbon composite material, comprising the following steps:

[0011] (1) Mesoporous carbon was prepared by using nano-casting method, with asphalt as carbon source and template agent as mold;

[0012] (2) Mesoporous carbon, diamond, and carbon fiber are mixed according to the formula to obtain composite powder;

[0013] (3) Place the dried composite powder into a mold and sinter it under pressure in an inert or reducing atmosphere to obtain carbon / carbon composite material.

[0014] Preferably, the asphalt in step (1) is one or more of natural asphalt, petroleum asphalt, and mesophase asphalt; the template agent is one or more of oxides such as barium oxide, magnesium oxide, iron oxide, copper oxide, zinc oxide, and potassium oxide, or chlorides such as sodium chloride, potassium chloride, and magnesium chloride.

[0015] Preferably, the mass ratio of asphalt to template agent in step (1) is 1:10 to 10:1.

[0016] Preferably, the nano-casting method in step (1) specifically includes: mixing asphalt and template agent evenly by ball milling or heating and stirring; heating the mixed powder to 600~1000 ℃ in an inert atmosphere for carbonization; then placing the carbonized mixed powder in a beaker and adding deionized water, hydrochloric acid or sulfuric acid to remove the template agent to obtain mesoporous carbon powder.

[0017] Preferably, in step (2), mesoporous carbon, diamond, and carbon fiber are mixed evenly by ball milling or ultrasonic dispersion and stirring to prepare composite powder.

[0018] Preferably, the drying temperature in step (3) is 50~60 ℃.

[0019] Preferably, the pressure sintering in step (3) includes hot pressing sintering or discharge plasma sintering.

[0020] Preferably, in step (3), the inert or reducing atmosphere is argon, nitrogen, argon-hydrogen mixture, etc.; the sintering temperature is 1600~2000 ℃, the sintering pressure is 30~100 MPa, and the holding time is 5~300 minutes.

[0021] Beneficial effects

[0022] This invention utilizes the high sintering activity of mesoporous carbon and the phase transformation-assisted self-pressurizing sintering effect of diamond to achieve low-temperature sintering preparation of carbon / carbon composite materials. Compared with traditional carbon / carbon composite material preparation technologies, the preparation method provided by this invention has advantages such as lower preparation temperature, shorter cycle time, and lower energy consumption. Moreover, the composite material also possesses excellent mechanical properties. This invention enables the simple and convenient preparation of high-performance carbon / carbon composite materials and has promising application prospects. Attached Figure Description

[0023] Figure 1 This is a physical image of sample B after sintering in Example 1 of this invention.

[0024] Figure 2 This is a density diagram of each sample in Example 1 of the present invention.

[0025] Figure 3 This is a Young's modulus diagram of each sample in Example 1 of the present invention.

[0026] Figure 4 These are bending strength diagrams of each sample in Embodiment 1 of the present invention.

[0027] Figure 5 These are bending strain diagrams of each sample in Embodiment 1 of the present invention.

[0028] Figure 6 These are the XRD patterns of each sample in Example 2 of this invention.

[0029] Figure 7 These are scanning electron microscope (SEM) images of the sample and mesoporous carbon powder in Example 3 of this invention. Detailed Implementation

[0030] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0031] Example 1

[0032] (1) Mesoporous carbon was prepared using a nano-casting method with petroleum asphalt as the carbon source and magnesium oxide as the mold. The asphalt and magnesium oxide in a mass ratio of 3:7 were mixed evenly by heating and stirring. The mixed powder was then heated to 900 °C in an inert atmosphere for carbonization. The carbonized powder was placed in a beaker and hydrochloric acid was added to remove the magnesium oxide, resulting in mesoporous carbon powder.

[0033] (2) The diamond particle size used in this embodiment is 50 nm and the carbon fiber length is 50 μm.

[0034] Mesoporous carbon was mixed with 10% diamond and 20% carbon fiber by ultrasonic dispersion and stirring. The resulting composite powder was denoted as sample A.

[0035] Using the same method, mesoporous carbon was mixed evenly with 10% diamond and 10% carbon fiber by mass, and the resulting composite powder was denoted as sample B.

[0036] Mesoporous carbon was mixed with 20% diamond and 10% carbon fiber by mass until homogeneous. The resulting composite powder was denoted as sample C.

[0037] Mesoporous carbon was mixed with 30% diamond and 10% carbon fiber by mass until homogeneous. The resulting composite powder was denoted as sample D.

[0038] (3) The dried composite powder was placed in a graphite mold and subjected to discharge plasma sintering at 1800 ℃ and 50 MPa for 5 min to obtain carbon / carbon composite material. A photograph of sample B after sintering is shown below. Figure 1 As shown.

[0039] Mechanical property tests were performed on the samples:

[0040] Bending strength, bending strain, and Young's modulus were measured using a universal testing machine with three-point bending tests. The sample size was 3x4x30 mm. The calculation formulas are shown below.

[0041]

[0042] in, is the bending strength, F is the maximum load, L is the span (i.e., the distance between the two lower support points), b is the width, and h is the thickness.

[0043]

[0044] in, It is bending strain. d is the deflection at the center of the sample (i.e., the distance the sample is pressed down), d is the thickness of the sample, and L is the span.

[0045]

[0046] in, is Young's modulus, L is the span, m is the slope of the initial straight line segment of the force-displacement curve, b is the sample width, and d is the sample thickness.

[0047] Density: The density of a material is measured using a density balance based on Archimedes' principle (buoyancy method).

[0048]

[0049] in, It is the density of the solid sample to be tested. It is the mass of the solid in air. It is the apparent mass of a solid when it is completely submerged in a liquid. It is the density of the auxiliary liquid.

[0050] The densities of each sample after sintering are as follows: Figure 2 As shown, the density of the carbon / carbon composite material generally decreases with the increase of diamond content, with the density reaching a maximum of 1.3915 g / cm³ in sample A. 3 The overall density remains between 1.33 and 1.40 g / cm³. 3 Between. From Figure 3 It can be observed that as the diamond content increases, the Young's modulus of the composite material increases. Furthermore, with the same diamond content, the composite material with a higher proportion of carbon fiber exhibits a higher Young's modulus (maximum 38.80 GPa).

[0051] pass Figure 4 , 5It can be seen that as the diamond content increases, the flexural strength and flexural strain of the composite material both show a decreasing trend. In sample A, which has the highest proportion of carbon fiber, the flexural strength and flexural strain are the lowest. Sample B, on the other hand, has the highest flexural strength (80.64 MPa) and flexural strain (2.11%).

[0052] The above case illustrates that, at lower temperatures and shorter preparation cycles, the mechanical properties of carbon / carbon composite materials can be controlled by adjusting the proportions of the composite components.

[0053] Example 2

[0054] (1) Mesoporous carbon was prepared using a nano-casting method with mesophase pitch as the carbon source and sodium chloride as the mold. The mesophase pitch and sodium oxide were mixed evenly in a mass ratio of 2:8 by heating and stirring. The mixed powder was then heated to 780 °C in an inert atmosphere for carbonization. The carbonized powder was placed in a beaker and hydrochloric acid was added to remove magnesium oxide, resulting in mesoporous carbon powder.

[0055] (2) The diamond particle size used in this embodiment is 100 nm and the carbon fiber length is 100 μm.

[0056] Mesoporous carbon was mixed with 10% diamond and 20% carbon fiber by ultrasonic dispersion and stirring. The resulting composite powder was denoted as sample E.

[0057] Using the same method, mesoporous carbon was mixed evenly with 10% diamond and 10% carbon fiber by mass, and the resulting composite powder was denoted as sample F.

[0058] Mesoporous carbon was mixed with 20% diamond and 10% carbon fiber by mass until homogeneous. The resulting composite powder was denoted as sample G.

[0059] Mesoporous carbon was mixed with 30% diamond and 10% carbon fiber by mass until homogeneous. The resulting composite powder was denoted as sample H.

[0060] (3) The dried composite powder was placed in a graphite mold and hot-pressed at 1800 ℃ and 40 MPa for 60 min. The XRD of the carbon / carbon composite material was obtained as follows: Figure 6 As shown.

[0061] from Figure 6 It is evident that no obvious characteristic diffraction peaks of diamond and carbon fiber were observed in the XRD of the composite material, indicating that the diamond underwent a phase transformation during the sintering process and was converted into onion graphite.

[0062] The above case illustrates that, at lower temperatures and shorter preparation cycles, the degree of graphitization of carbon / carbon composite materials can be controlled by adjusting the proportions of the composite components, especially the content of diamond powder.

[0063] Example 3

[0064] (1) Mesoporous carbon was prepared using a nano-casting method with natural bitumen as the carbon source and magnesium chloride as the mold. Natural bitumen and magnesium oxide were mixed evenly in a mass ratio of 3:7 by heating and stirring. The mixed powder was then heated to 750 °C in an inert atmosphere for carbonization. The carbonized powder was placed in a beaker and dilute hydrochloric acid was added to remove magnesium chloride, yielding mesoporous carbon powder.

[0065] (2) Mesoporous carbon is mixed with 10% diamond (50 nm in diameter) and 20% carbon fiber (50 μm in length) by ultrasonic dispersion and stirring. The resulting composite powder is denoted as Sample I.

[0066] (3) The dried composite powder was placed in a graphite mold and subjected to discharge plasma sintering at 1900 ℃ and 80 MPa for 5 min. The microstructure of the mesoporous carbon powder and sintered sample I is shown in the figure. Figure 7 As shown.

[0067] from Figure 7 It is evident that the mesoporous carbon powder exhibits a distinct cavity structure with thin pore walls. In the cross-section of sample I, clearly visible carbon fibers, approximately 10 μm in diameter, are uniformly distributed without significant agglomeration. Several pores appear in the cross-section of sample I, likely left by the carbon fibers being pulled out of the composite mass during sample fracture. The image also shows uniformly distributed light-colored particles at the nanoscale, comparable in size to onion graphite formed by the diamond phase transition; these light-colored particles are presumably onion graphite particles.

[0068] In summary, the phase transformation expansion of diamond powder generates local pressure, and the composite carbon fiber increases the bulk fracture resistance. Therefore, by reasonably adjusting the ratio of composite components, the mechanical properties of carbon / carbon composite materials can be enhanced and controlled.

Claims

1. A carbon / carbon composite material prepared from disordered mesoporous carbon, characterized in that, The carbon / carbon composite material is prepared by pressure sintering of composite powder obtained by mixing mesoporous carbon, diamond and carbon fiber.

2. The carbon / carbon composite material prepared from disordered mesoporous carbon according to claim 1, characterized in that, The composite powder contains 30-90% mesoporous carbon, 5-30% diamond, and 5-40% carbon fiber by mass fraction.

3. The carbon / carbon composite material prepared from disordered mesoporous carbon according to claim 1, characterized in that, The mesoporous carbon has a pore size of 4~50 nm, the diamond has a particle size of 10 nm~10 μm, and the carbon fiber has a length of 10~500 μm.

4. A method for preparing a carbon / carbon composite material from disordered mesoporous carbon, comprising the following steps: (1) Mesoporous carbon was prepared by using nano-casting method, with asphalt as carbon source and template agent as mold; (2) Mesoporous carbon, diamond, and carbon fiber are mixed according to the formula to obtain composite powder; (3) Place the dried composite powder into a mold and sinter it under pressure in an inert or reducing atmosphere to obtain carbon / carbon composite material.

5. The preparation method according to claim 4, characterized in that, In step (1), the asphalt is one or more of natural asphalt, petroleum asphalt, and mesophase asphalt; the template agent is one or more of barium oxide, magnesium oxide, iron oxide, copper oxide, zinc oxide, potassium oxide, or sodium chloride, potassium chloride, and magnesium chloride.

6. The preparation method according to claim 4, characterized in that, In step (1), the mass ratio of asphalt to template agent is 1:10 to 10:

1.

7. The preparation method according to claim 4, characterized in that, The nano-casting method in step (1) specifically includes: mixing asphalt and template agent evenly by ball milling or heating and stirring, and heating the mixed powder to 600~1000 ℃ in an inert atmosphere for carbonization; then placing the carbonized mixed powder in a beaker and adding deionized water, hydrochloric acid or sulfuric acid to remove the template agent to obtain mesoporous carbon powder.

8. The preparation method according to claim 4, characterized in that, In step (2), mesoporous carbon, diamond, and carbon fiber are mixed evenly by ball milling or ultrasonic dispersion and stirring to prepare composite powder.

9. The preparation method according to claim 4, characterized in that, The pressure sintering in step (3) includes hot pressing sintering or discharge plasma sintering.

10. The preparation method according to claim 4, characterized in that, In step (3), the inert or reducing atmosphere is argon, nitrogen or argon-hydrogen mixture; the sintering temperature is 1600~2000 ℃, the sintering pressure is 30~100 MPa, and the holding time is 5~300 minutes.

Images