Short carbon fiber reinforced carbon-ceramic composite material

Abstract

The invention belongs to the field of carbon-based composite materials, and particularly relates to a short carbon fiber reinforced carbon-ceramic composite material. The preparation method comprises the following steps: mixing mesophase pitch powder and resin powder according to a mass ratio of (5-7): (3-5) to obtain a mixed binder; uniformly mixing nanoscale carbon black serving as a reinforcing phase and sodium dodecyl sulfate serving as a dispersing agent to obtain modified nano carbon black; uniformly mixing the obtained mixed binder with modified carbon black according to the ratio of 100: (1-4) to obtain a mixed binder; weighing the modified carbon black enhanced mixed binder and short carbon fibers according to a mass ratio of (40-60): (40-60), and uniformly mixing to obtain pressed powder; and carrying out hot press molding, carbonization and reactive infiltration to obtain the short carbon fiber reinforced carbon-ceramic composite material. The process is simple and controllable, the obtained product is high in density, high in strength and high in friction coefficient stability, and industrial application is facilitated.

Description

Technical Field

[0001] This invention belongs to the field of carbon-based composite materials, specifically relating to a short carbon fiber reinforced carbon ceramic composite material. Background Technology

[0002] In recent years, lightweight, high-strength, and high-temperature resistant carbon-ceramic composite materials have gradually replaced traditional cast steel in braking systems for automobiles, sports cars, and rail transportation. They offer advantages such as a high and stable coefficient of friction and excellent wear resistance during braking, significantly improving the driving and riding experience. Among these, short-cut carbon fiber reinforced carbon-ceramic composite materials have become a hot research and industrialization area in recent years due to their advantages in formability, isotropic mechanical properties, and cost control.

[0003] Traditional carbon-ceramic composite material preparation processes are based on continuous carbon fiber fabric preforms, using methods such as multiple vapor deposition (CVI) densification and reactive melt infiltration (LSI) to achieve composite structures. However, these processes generally suffer from long cycle times, high porosity, and high preparation costs, limiting their large-scale application. In contrast, carbon-ceramic composite materials prepared using chopped carbon fiber powder and binders can be molded into complex structural parts in a single step through processes such as hot molding and carbonization, significantly improving preparation efficiency and reducing manufacturing costs, thus showing promising prospects for engineering applications.

[0004] Currently, the preparation process of chopped carbon fiber reinforced carbon-ceramic composites still faces several technical bottlenecks: First, insufficient bonding strength between chopped fibers and binders leads to local mechanical property degradation; second, molding and heat treatment process parameters have a significant impact on the microstructure evolution and final performance of the material, and there is still a lack of systematic optimization and control methods.

[0005] Patent 202111634827.4 discloses a method for preparing short-cut carbon fiber composite materials. After the raw materials are washed with acid and alkali, dried, oxidized and surface mechanically modified, they are mixed with resin and prepared by molding, carbonization, vapor deposition and graphitization. This method requires 36 hours of vapor deposition densification and has extremely high cost.

[0006] Patent ZL201911302480.6 discloses a carbon-ceramic composite brake disc and its preparation method. The method involves coating a carbon fiber braid with a ceramic slurry, followed by carbonization and densification to 2.0 g / cm³ via vapor deposition. This method involves carbon fiber braiding and vapor deposition, requiring a lengthy preparation process.

[0007] The general process for preparing carbon-ceramic composites from chopped fibers involves mixing chopped fibers with a binder, followed by hot molding and melt infiltration of Si. This process has a short cycle time and good material uniformity, but its mechanical strength has not yet reached that of carbon-ceramic composites prepared from woven carbon fibers and vapor deposition, thus limiting its applications. The key factors affecting the mechanical properties of carbon-ceramic composites prepared from chopped carbon fibers are the strength of the binder after carbonization and its bonding performance with the carbon fibers.

[0008] Therefore, there is an urgent need to develop a low-cost, simple, and high-performance short-cut carbon fiber carbon-ceramic composite material preparation technology to solve the problems of low preparation efficiency, unstable interface structure, and large performance fluctuations in existing technologies, and to meet the comprehensive requirements of high-end application fields for high strength, wear resistance, and high thermal stability of materials. Summary of the Invention

[0009] This invention provides a method for preparing carbon-ceramic composite materials from short carbon fibers. By optimizing the binder system and modifying with nano-carbon black, the short fiber carbon-ceramic composite material achieves high density, high strength, and stable friction coefficient.

[0010] This invention discloses a short carbon fiber reinforced carbon-ceramic composite material, which is prepared through the following steps:

[0011] Step 1: Preparation of Mixed Adhesive

[0012] Mesophase asphalt powder (particle size 15-100 micrometers) and resin powder (phenolic resin, epoxy resin or furan resin, particle size 15-100 micrometers) are mixed at a mass ratio of 5-7:3-5 to obtain a mixed binder.

[0013] Step 2: Enhance Phase Dispersion

[0014] Nanoscale carbon black was used as the reinforcing phase, and sodium dodecyl sulfonate was used as the dispersant. The carbon black was dissolved in acetone at a mass ratio of 1:1 to 5 and then ultrasonically dispersed to obtain a suspension. The suspension was dried to obtain modified nanoscale carbon black. Subsequently, the mixed binder obtained in step one was mixed with the modified carbon black at a mass ratio of 100:1 to 4 and then crushed to obtain a mixed binder reinforced with modified carbon black.

[0015] Step 3: Powder Preparation

[0016] Modified carbon black reinforced mixed binder and short-cut carbon fibers are weighed and mixed evenly at a mass ratio of 40-60:40-60 to obtain compressed powder.

[0017] Preferably, the length of the chopped carbon fiber is 5 to 8 mm.

[0018] Step 4: Hot pressing

[0019] Pour the powder into a mold heated to 100-200 degrees Celsius and hot press it at 5-10 MPa.

[0020] Preferably, the mold temperature is 120–180 degrees Celsius.

[0021] Preferably, the hot pressing time is 15 to 30 minutes.

[0022] Step 5: Carbonization

[0023] The hot-pressed block is placed in a calcining furnace and carbonized at 950-1050 degrees Celsius in a nitrogen atmosphere for 3-5 hours to obtain the calcined body.

[0024] Preferably, the density of the calcined body is 1.0 to 1.4 g / cm3.

[0025] Step Six: Reaction Melting

[0026] The carbonized calcined body is placed in a graphite crucible. Si powder is weighed and filled into the graphite crucible at a mass ratio of 1.5 to 2.0:1. The crucible is then sealed and placed in a melting furnace. Melting is carried out at 1600 to 1800 degrees Celsius for at least 1 hour, preferably 1 to 3 hours, so that Si reacts fully with the carbon in the bulk to form SiC.

[0027] The advantage of using mesophase pitch in this invention lies in the fact that it contains anisotropic liquid crystal spherulites (mesophase), exhibiting a typical liquid crystal texture under microscopic observation. It is mainly composed of polycyclic aromatic planar molecules with large molecular size and low polarity, making it prone to directional stacking. After carbonization, it easily forms a fine, uniform mosaic or fibrous texture. By bridging with long-chain resin molecules, it improves the uniformity of the friction surface, thereby enhancing the stability of the friction coefficient.

[0028] In step one of this invention, the mass ratio of mesophase pitch powder to resin powder is preferably 5.5~6.5:3.5~4.5, and more preferably 6:4.

[0029] The present invention uses mesophase pitch powder and resin powder in a mass ratio of 5-7:3-5 because at this ratio, the resin will fully wet the mesophase pitch and carbon fiber during hot pressing, resulting in the best material density after hot pressing. Too much mesophase pitch powder will lead to difficulties in molding, rough material surface and too many defects, while too little will lead to poor strength after carbonization.

[0030] The resin is selected from at least one of phenolic resin, epoxy resin, and furan resin.

[0031] In step two of this invention, nano-sized carbon black is used as the reinforcing phase, and sodium dodecyl sulfonate is used as the dispersant. The carbon black is dissolved in acetone at a mass ratio of 1:1 to 4, and the mixture is ultrasonically dispersed for 30 to 60 minutes to obtain a suspension. The suspension is then dried in an oven at 50 to 70 degrees Celsius for 5 to 8 hours to obtain modified nano-carbon black.

[0032] As a further preferred option, the mass ratio of nano-sized carbon black to sodium dodecyl sulfonate is 2:4.5 to 5.5. This includes ratios such as 2:4.5, 2:5, and 2:5.5.

[0033] In step two of this invention, the mixed binder and modified carbon black are mixed and crushed at a mass ratio of 100:1 to 4 to obtain a mixed binder reinforced with modified carbon black with a particle size of less than or equal to 100 micrometers.

[0034] As a further preferred option, in step two, the mass ratio of the mixed binder to the modified carbon black is 100:1.5 to 2.5; this includes small ratio ranges such as 100:1.8 to 2.2 and 100:1.9 to 2.1.

[0035] In step two of this invention, the ratio of the mixed binder to the modified carbon black is controlled to be 100:1 to 4 (preferably 100:1.5 to 2.5) because the strengthening effect of carbon black is more obvious at this ratio. If the amount of modified carbon black is too low, the strengthening effect will be minimal, and if it is too high, the sample will crack due to inconsistent coefficients of thermal expansion during the carbonization process.

[0036] In the process of technological exploration, other dispersants were also tried in step two; however, other dispersants (such as ethanol, acetone, sodium methyl cellulose, etc.) would cause rapid agglomeration of nano-sized carbon black, thereby reducing the performance of the product.

[0037] As a further preferred option, in step three, during the preparation of the powder, the mass ratio of the modified carbon black reinforced mixed binder to the short-cut carbon fibers is 40-60:40-60, preferably 45-55:45-55. This is because the carbon black modified binder has already undergone partial pre-reaction, which affects its formability. If too much modified carbon black reinforced mixed binder is used, it will lead to excessive elastic aftereffects and cracking problems. If too little is used, it will lead to poor formability.

[0038] In step three, the powder is obtained by mixing in the drum mixer for 1 to 2 hours.

[0039] Preferably, the length of the chopped carbon fiber is 6 to 7 mm.

[0040] The carbon-ceramic composite material prepared by the present invention using short-cut carbon fibers has a density >2.0 g / cm3, a hardness >90 HSD, and a compressive strength >200 MPa.

[0041] The test method is to use an HT1000 high-temperature friction and wear tester to test the carbon-ceramic composite material in this invention. The friction pair is a copper-based powder metallurgy material with a friction radius of 3 mm and a rotation speed of 600 r / min.

[0042] Principles and advantages

[0043] In the preparation of carbon-ceramic composites from short carbon fibers, controlling the carbonization texture of the binder holds promise for enhancing the performance of short-cut C / C-SiC fibers. Traditional binders are typically phenolic, epoxy, and polyetheretherketone resins, but their low degree of carbonization and crosslinking leads to insufficient material properties. Mesophase pitch, as another preferred binder material, possesses characteristics such as high fluidity and high residual carbon content, but it tends to form large-scale, fluidized carbonization textures, the strength of which is far lower than that of fine mosaic textures. Therefore, the planar macromolecules of pitch are linked by long molecular chains in the resin. Using the high specific surface area of ​​nano-carbon black to induce the carbonization of the binder pitch to form a fine-scale isotropic mosaic texture holds promise for improving the overall performance of carbon-ceramic composites prepared from short-cut carbon fibers. Attached Figure Description

[0044] Figure 1 A physical image of the product obtained in Example 1.

[0045] Figure 2 The images show the surface morphology of the wear tracks after friction and wear tests on the products of Example 1 and Comparative Example 1. It is clearly visible that the wear track surface of Example 1 is uniform, with only minor wear. In contrast, the surface of Comparative Example 1 shows obvious frictional damage. Detailed Implementation

[0046] Example 1

[0047] Mesophase pitch powder (particle size 30-75 micrometers) and phenolic resin powder (particle size 30-75 micrometers) were weighed at a ratio of 60g and 40g respectively and mixed to obtain a mixed binder. 2g of nano-sized carbon black and 5g of sodium dodecyl sulfonate were dissolved in acetone and ultrasonically dispersed for 45 minutes to obtain a suspension. The suspension was dried in an oven at 60°C for 6.5 hours to obtain modified nano-carbon black (particle size ≤ 100 micrometers). Subsequently, 100g of the mixed binder and 2g of modified carbon black were mixed and placed in a vibrating crusher, and crushed for 10 minutes to obtain a modified carbon black-reinforced mixed binder (particle size ≤ 100 micrometers). 100g of the modified carbon black-reinforced mixed binder and 100g of 6.5mm long carbon fibers were weighed and mixed in a drum mixer for 1.5 hours to obtain pressed powder. The pressed powder was poured into a mold heated to 150°C and pressed under 8MPa pressure for 20 minutes to obtain a compact. The pressed preform was calcined in a calcining furnace at 1000°C under a nitrogen atmosphere for 3 hours to obtain a calcined body. The density of the calcined body was 1.35 g / cm³. Si powder at a mass ratio of 1.8:1 was then placed in a graphite crucible and infiltrated at 1700°C for 2 hours. In this embodiment, the carbon-ceramic composite material prepared from short-cut carbon fibers had a density of 2.12 g / cm³, a hardness of 105 HSD, and a compressive strength of 230 MPa. The average coefficient of friction was 0.32, and the coefficient of friction stability was 0.91.

[0048] Example 2

[0049] Mesophase pitch powder (particle size 30-75 μm) and phenolic resin powder (particle size 30-75 μm) were weighed at 55 g and 45 g respectively and mixed to obtain a mixed binder. 2 g of nano-sized carbon black and 5 g of sodium dodecyl sulfonate were dissolved in acetone and ultrasonically dispersed for 45 minutes to obtain a suspension. The suspension was dried in an oven at 60°C for 6.5 hours to obtain modified nano-carbon black (particle size ≤ 100 μm). Subsequently, 100 g of the mixed binder and 2 g of modified carbon black were mixed and placed in a vibrating crusher, and crushed for 10 minutes to obtain a modified carbon black-reinforced mixed binder (particle size ≤ 100 μm). 100 g of the modified carbon black-reinforced mixed binder and 120 g of 6.5 mm long carbon fibers were weighed and mixed in a drum mixer for 1.5 hours to obtain pressed powder. The pressed powder was poured into a mold heated to 150°C and pressed under 10 MPa pressure for 20 minutes to obtain a pressed compact. The pressed preform was calcined in a calcining furnace at 1000°C under a nitrogen atmosphere for 3 hours to obtain a calcined body. The density of the calcined body was 1.24 g / cm³. Si powder at a mass ratio of 1.9:1 was then placed in a graphite crucible and infiltrated at 1750°C for 2 hours. In this embodiment, the carbon-ceramic composite material prepared from short-cut carbon fibers had a density of 2.04 g / cm³, a hardness of 97 HSD, and a compressive strength of 217 MPa. The average coefficient of friction was 0.31, and the coefficient of friction stability was 0.87.

[0050] Example 3

[0051] Mesophase pitch powder (particle size 30-75 μm), phenolic resin powder (particle size 30-75 μm), and furan resin powder (particle size 30-75 μm) were weighed at 65 g, 20 g, and 15 g respectively and mixed to obtain a mixed binder. 2.5 g of nano-sized carbon black and 6 g of sodium dodecyl sulfonate were dissolved in acetone and ultrasonically dispersed for 45 minutes to obtain a suspension. The suspension was dried in an oven at 60°C for 7 hours to obtain modified nano-carbon black (particle size ≤ 100 μm). Subsequently, 100 g of the mixed binder was mixed with 2.5 g of modified carbon black and placed in a vibrating crusher, crushed for 10 minutes to obtain a modified carbon black-reinforced mixed binder (particle size ≤ 100 μm). 100 g of the modified carbon black-reinforced mixed binder was weighed and mixed with 110 g of 6.5 mm long carbon fibers in a drum mixer for 1.5 hours to obtain pressed powder. The mold was heated to 160°C, and the powder was poured in. The mixture was pressed at 10 MPa for 20 minutes to obtain a compact. The compact was then calcined in a calcining furnace at 1000°C under a nitrogen atmosphere for 3 hours to obtain a calcined body. The density of the calcined body was 1.29 g / cm³. Si powder at a mass ratio of 1.9:1 was used to embed the calcined body in a graphite crucible, and the mixture was infiltrated at 1750°C for 2 hours. In this embodiment, the carbon-ceramic composite material prepared from chopped carbon fibers had a density of 2.09 g / cm³, a hardness of 103 HSD, and a compressive strength of 224 MPa. The average coefficient of friction was 0.33, and the coefficient of friction stability was 0.84.

[0052] Example 4

[0053] Mesophase pitch powder (particle size 30-75 μm), phenolic resin powder (particle size 30-75 μm), and epoxy resin powder (particle size 30-75 μm) were weighed at 65 g, 25 g, and 10 g respectively and mixed to obtain a mixed binder. 2.5 g of nano-sized carbon black and 6 g of sodium dodecyl sulfonate were dissolved in acetone and ultrasonically dispersed for 45 minutes to obtain a suspension. The suspension was dried in an oven at 60°C for 7 hours to obtain modified nano-carbon black (particle size ≤ 100 μm). Subsequently, 100 g of the mixed binder was mixed with 2.5 g of modified carbon black and placed in a vibrating crusher, crushed for 10 minutes to obtain a modified carbon black-reinforced mixed binder (particle size ≤ 100 μm). 100 g of the modified carbon black-reinforced mixed binder was weighed and mixed with 85 g of 6.5 mm long carbon fibers in a drum mixer for 1.5 hours to obtain pressed powder. The mold was heated to 160°C, and the powder was poured in. The mixture was pressed at 10 MPa for 20 minutes to obtain a compact. The compact was then calcined in a calcining furnace at 1000°C under a nitrogen atmosphere for 3 hours to obtain a calcined body. The density of the calcined body was 1.21 g / cm³. Si powder at a mass ratio of 1.8:1 was used to embed the calcined body in a graphite crucible, and the mixture was infiltrated at 1700°C for 2 hours. In this embodiment, the carbon-ceramic composite material prepared from short-cut carbon fibers had a density of 2.11 g / cm³, a hardness of 110 HSD, and a compressive strength of 234 MPa. The average coefficient of friction was 0.35, and the coefficient of friction stability was 0.83.

[0054] Example 5

[0055] Mesophase pitch powder (particle size 30-75 μm), phenolic resin powder (particle size 30-75 μm), and furan resin powder (particle size 30-75 μm) were weighed at 60 g, 25 g, and 15 g respectively and mixed to obtain a mixed binder. 2.5 g of nano-sized carbon black and 6 g of sodium dodecyl sulfonate were dissolved in acetone and ultrasonically dispersed for 45 minutes to obtain a suspension. The suspension was dried at 60°C for 7 hours to obtain modified nano-carbon black (particle size ≤ 100 μm). Subsequently, 100 g of the mixed binder was mixed with 2.5 g of modified carbon black and crushed in a vibrating crusher for 10 minutes to obtain a modified carbon black-reinforced mixed binder (particle size ≤ 100 μm). 100 g of the modified carbon black-reinforced mixed binder was mixed with 95 g of 6.5 mm long carbon fibers in a drum mixer for 1.5 hours to obtain pressed powder. The mold was heated to 160°C and pressed under 10 MPa pressure for 20 minutes to obtain a pressed compact. Calcination: 1000℃, nitrogen atmosphere for 3 hours. Calcinated bulk density: 1.27 g / cm³. Melting: Si powder / calcined bulk = 1.9:1, 1750℃, 2 hours. In this embodiment, the carbon-ceramic composite material prepared from chopped carbon fibers has a density of 2.07 g / cm³, a hardness of 101 HSD, and a compressive strength of 221 MPa. The average coefficient of friction is 0.34, and the coefficient of friction stability is 0.83.

[0056] Example 6

[0057] Mesophase pitch powder (particle size 30-75 μm), phenolic resin powder (particle size 30-75 μm), and epoxy resin powder (particle size 30-75 μm) were weighed at 65 g, 25 g, and 10 g respectively and mixed to obtain a mixed binder. 2.5 g of nano-carbon black and 6 g of sodium dodecyl sulfonate were ultrasonically dispersed for 45 minutes. After drying for 7 hours, modified nano-carbon black (particle size ≤ 100 μm) was obtained. 100 g of the mixed binder and 2.5 g of modified nano-carbon black were crushed for 10 minutes to obtain a reinforced mixed binder (particle size ≤ 100 μm). 100 g of the reinforced mixed binder was weighed and mixed with 120 g of 6.5 mm long carbon fiber for 1.5 hours to obtain pressed powder. The mold was heated to 160℃ and pressed under 10 MPa pressure for 20 minutes to obtain a pressed compact. Calcination: 1000℃ under nitrogen for 3 hours, the calcined volume density was 1.31 g / cm³. Melting and infiltration: Si powder / calcined body = 1.9:1, 1750℃, 2 hours. In this example, the carbon-ceramic composite material prepared from short-cut carbon fibers has a density of 2.11 g / cm3, a hardness of 106 HSD, and a compressive strength of 228 MPa. The average coefficient of friction is 0.35, and the coefficient of friction stability is 0.85.

[0058] Comparative Example 1

[0059] Mesophase pitch powder (particle size 30-75 μm) and phenolic resin powder (particle size 30-75 μm) were weighed at a ratio of 35 g and 65 g respectively and mixed to obtain a mixed binder (particle size ≤ 100 μm). 100 g of the resulting mixed binder was mixed with 100 g of 6.5 mm long carbon fibers in a roller mixer for 1.5 h to obtain pressed powder. The pressed powder was poured into a mold heated to 160 °C and pressed under 10 MPa pressure for 20 minutes to obtain a compact. The compact was calcined in a calcining furnace at 1000 °C in a nitrogen atmosphere for 3 h to obtain a calcined body. The density of the calcined body was 0.87 g / cm³. Si powder at a mass ratio of 1.8:1 was used to embed the calcined body in a graphite crucible, and it was infiltrated at 1700 °C for 2 h. In this comparative example, the carbon-ceramic composite material prepared from short-cut carbon fibers had a density of 1.91 g / cm³, a hardness of 87 HSD, and a compressive strength of 184 MPa. The average coefficient of friction is 0.28, and the coefficient of friction stability is 0.72.

[0060] Comparative Example 2

[0061] Mesophase pitch powder (particle size 30-75 micrometers) and phenolic resin powder (particle size 30-75 micrometers) were weighed in equal amounts of 50g and mixed to obtain a mixed binder (particle size ≤ 100 micrometers). 2g of nano-sized carbon black and 2g of sodium dodecyl sulfonate were dissolved in acetone and ultrasonically dispersed for 45 minutes to obtain a suspension. The suspension was dried in an oven at 60°C for 6.5 hours to obtain modified nano-carbon black (particle size ≤ 100 micrometers). Subsequently, 100g of the mixed binder and 2g of modified carbon black were mixed and placed in a vibrating crusher, and crushed for 10 minutes to obtain a modified carbon black-reinforced mixed binder (particle size ≤ 100 micrometers). 100g of the modified carbon black-reinforced mixed binder and 200g of 6.5mm long carbon fibers were weighed and mixed in a drum mixer for 1.8 hours to obtain pressed powder. The mold was heated to 160°C, and the powder was poured in. The mixture was pressed at 10 MPa for 25 minutes to obtain a compact. The compact was then calcined in a calcining furnace at 1000°C under a nitrogen atmosphere for 3 hours to obtain a calcined body. The density of the calcined body was 0.77 g / cm³. Si powder at a mass ratio of 1.8:1 was used to embed the calcined body in a graphite crucible, and the mixture was infiltrated at 1700°C for 2 hours. In this comparative example, the carbon-ceramic composite material prepared from short-cut carbon fibers had a density of 1.84 g / cm³, a hardness of 68 HSD, and a compressive strength of 151 MPa. The average coefficient of friction was 0.26, and the coefficient of friction stability was 0.70.

[0062] Comparative Example 3

[0063] Mesophase pitch powder (particle size 30-75 μm), phenolic resin powder (particle size 30-75 μm), and furan resin powder (particle size 30-75 μm) were weighed at 50 g, 30 g, and 20 g respectively, and mixed to obtain a mixed binder (particle size ≤ 100 μm). 2 g of nano-sized carbon black and 12 g of sodium dodecyl sulfonate were dissolved in acetone and ultrasonically dispersed for 45 minutes to obtain a suspension. The suspension was dried in an oven at 60°C for 6.5 hours to obtain modified nano-carbon black (particle size ≤ 100 μm). Subsequently, 100 g of the mixed binder was mixed with 2 g of modified carbon black and placed in a vibrating crusher, and crushed for 10 minutes to obtain a modified carbon black-reinforced mixed binder (particle size ≤ 100 μm). 100 g of the modified carbon black-reinforced mixed binder was weighed and mixed with 55 g of 6.5 mm long carbon fibers in a drum mixer for 1.8 hours to obtain pressed powder. The mold was heated to 160°C, and the powder was poured in. The mixture was pressed at 10 MPa for 25 minutes to obtain a compact. The compact was then calcined in a calcining furnace at 1000°C under a nitrogen atmosphere for 3 hours to obtain a calcined body. The density of the calcined body was 0.81 g / cm³. Si powder at a mass ratio of 1.8:1 was used to embed the calcined body in a graphite crucible, and the mixture was infiltrated at 1700°C for 2 hours. In this comparative example, the carbon-ceramic composite material prepared from short-cut carbon fibers had a density of 1.87 g / cm³, a hardness of 95 HSD, and a compressive strength of 168 MPa. The average coefficient of friction was 0.27, and the coefficient of friction stability was 0.73.

[0064] Comparative Example 4

[0065] Mesophase pitch powder (particle size 30-75 μm), phenolic resin powder (particle size 30-75 μm), furan resin powder (particle size 30-75 μm), and epoxy resin powder (particle size 30-75 μm) were weighed and mixed in the following proportions of 50 g, 25 g, 20 g, and 5 g, respectively, to obtain a mixed binder (particle size ≤ 100 μm). 2 g of nano-sized carbon black and 12 g of sodium dodecyl sulfonate were dissolved in acetone and ultrasonically dispersed for 45 minutes to obtain a suspension. The suspension was dried in an oven at 60°C for 6.5 hours to obtain modified nano-carbon black (particle size ≤ 100 μm). Subsequently, 100 g of the mixed binder and 2 g of modified carbon black were mixed and placed in a vibrating crusher, and crushed for 10 minutes to obtain a modified carbon black-reinforced mixed binder (particle size ≤ 100 μm). 100g of modified carbon black-reinforced mixed binder and 100g of 10mm long carbon fibers were weighed and mixed in a roller mixer for 1.5h to obtain pressed powder. The pressed powder was poured into a mold heated to 160°C and pressed under 10MPa pressure for 45 minutes to obtain a compact. The compact was then calcined in a calcining furnace at 1000°C in a nitrogen atmosphere for 3h to obtain a calcined body. The density of the calcined body was 0.79g / cm³. Si powder at a mass ratio of 1.8:1 was used to embed the calcined body in a graphite crucible, and it was infiltrated at 1700°C for 2h. In this comparative example, the carbon-ceramic composite material prepared from short-cut carbon fibers had a density of 1.95g / cm³, a hardness of 88 HSD, and a compressive strength of 174MPa. The average coefficient of friction was 0.25, and the coefficient of friction stability was 0.68.

[0066] Comparative Example 5

[0067] Phenolic resin powder (particle size 30-75 μm), furan resin powder (particle size 30-75 μm), and epoxy resin powder (particle size 30-75 μm) were weighed at 60 g, 25 g, and 15 g respectively, and mixed to obtain a mixed binder (particle size ≤ 100 μm). 2.5 g of nano-sized carbon black and 6 g of sodium dodecyl sulfonate were dissolved in acetone and ultrasonically dispersed for 45 minutes to obtain a suspension. The suspension was dried in an oven at 60°C for 7 hours to obtain modified nano-carbon black (particle size ≤ 100 μm). Subsequently, 100 g of the mixed binder was mixed with 2.5 g of modified carbon black and placed in a vibrating crusher, crushed for 10 minutes to obtain a modified carbon black-reinforced mixed binder (particle size ≤ 100 μm). 100 g of the modified carbon black-reinforced mixed binder and 100 g of 10 mm long carbon fibers were weighed and mixed in a drum mixer for 1.5 hours to obtain pressed powder. The mold was heated to 160°C, and the powder was poured in. The mixture was pressed at 10 MPa for 45 minutes to obtain a compact. The compact was then calcined in a calcining furnace at 1000°C under a nitrogen atmosphere for 3 hours to obtain a calcined body. The density of the calcined body was 0.48 g / cm³. Si powder at a mass ratio of 1.8:1 was used to embed the calcined body in a graphite crucible, and the mixture was infiltrated at 1700°C for 2 hours. In this comparative example, the carbon-ceramic composite material prepared from short-cut carbon fibers had a density of 0.97 g / cm³, a hardness of 45 HSD, and a compressive strength of 97 MPa. The average coefficient of friction was 0.22, and the coefficient of friction stability was 0.65.

[0068] Comparative Example 6

[0069] Mesophase pitch powder (particle size 30-75 μm), phenolic resin powder (particle size 30-75 μm), and furan resin powder (particle size 30-75 μm) were weighed in batches of 50g, 25g, and 25g respectively, and mixed to obtain a mixed binder (particle size ≤ 100 μm). 2g of nano-carbon black and 6g of sodium dodecyl sulfonate were ultrasonically dispersed for 45 minutes. After drying for 6.5 hours, modified nano-carbon black (particle size ≤ 100 μm) was obtained. 100g of the mixed binder and 2g of modified nano-carbon black were crushed for 10 minutes to obtain a reinforced mixed binder. 100g of the reinforced mixed binder was weighed and mixed with 150g of 6.5mm long carbon fibers for 1.8 hours to obtain pressed powder. The mold was heated to 160℃ and pressed under 10MPa pressure for 25 minutes to obtain a pressed compact. Calcination: 1000℃ under nitrogen for 3 hours, the calcined volume density was 0.75g / cm³. Melting and infiltration: Si powder / calcined body = 1.8:1, 1700℃, 2 hours. In this comparative example, the carbon-ceramic composite material prepared by short-cut carbon fibers has a density of 1.82 g / cm3, a hardness of 71 HSD, a compressive strength of 155 MPa, an average coefficient of friction of 0.29, and a coefficient of friction stability of 0.71.

[0070] Comparative Example 7

[0071] Mesophase pitch powder (particle size 100-150 μm) and phenolic resin powder (particle size 100-150 μm) were weighed at a ratio of 60 g and 40 g respectively and mixed to obtain a mixed binder (particle size ≤ 200 μm). 2 g of nano-sized carbon black and 5 g of sodium dodecyl sulfonate were dissolved in acetone and ultrasonically dispersed for 45 minutes to obtain a suspension. The suspension was dried in an oven at 60°C for 6.5 hours to obtain modified nano-carbon black (particle size ≤ 100 μm). Subsequently, 100 g of the mixed binder and 2 g of modified carbon black were mixed and placed in a vibrating crusher, and crushed for 10 minutes to obtain a modified carbon black-reinforced mixed binder. 100 g of the modified carbon black-reinforced mixed binder and 100 g of 6.5 mm long carbon fibers were weighed and mixed in a drum mixer for 1.5 hours to obtain pressed powder. The mold was heated to 150°C, and the powder was poured in. The mixture was pressed at 8 MPa for 20 minutes to obtain a compact. The compact was then calcined in a calcining furnace at 1000°C under a nitrogen atmosphere for 3 hours to obtain a calcined body. The density of the calcined body was 1.13 g / cm³. Si powder at a mass ratio of 1.8:1 was used to embed the calcined body in a graphite crucible, and the mixture was infiltrated at 1700°C for 2 hours. In this comparative example, the carbon-ceramic composite material prepared from short-cut carbon fibers had a density of 1.64 g / cm³, a hardness of 84 HSD, and a compressive strength of 159 MPa. The average coefficient of friction was 0.23, and the coefficient of friction stability was 0.77.

[0072] Comparative Example 8

[0073] Ordinary coal tar pitch powder (non-mesophase pitch, particle size 30–75 μm) and phenolic resin powder (particle size 30–75 μm) were weighed at a ratio of 60 g and 40 g respectively and mixed to obtain a mixed binder. 2 g of nano-sized carbon black and 5 g of sodium dodecyl sulfonate were dissolved in acetone and ultrasonically dispersed for 45 minutes to obtain a suspension. The suspension was dried in an oven at 60 °C for 6.5 hours to obtain modified nano-carbon black (particle size ≤ 100 μm). Subsequently, 100 g of the mixed binder and 2 g of modified carbon black were mixed and placed in a vibrating crusher, and crushed for 10 minutes to obtain a modified carbon black-reinforced mixed binder (particle size ≤ 100 μm).

[0074] 100 g of modified carbon black-reinforced mixed binder and 100 g of 6.5 mm long carbon fibers were weighed and mixed in a roller mixer for 1.5 h to obtain pressed powder. The pressed powder was poured into a mold heated to 150 ℃ and pressed under a pressure of 8 MPa for 20 minutes to obtain a compact. The compact was calcined in a calcining furnace at 1000 ℃ in a nitrogen atmosphere for 3 h to obtain a calcined body with a density of 1.18 g / cm³. The calcined body was buried in a graphite crucible with Si powder at a mass ratio of 1.8:1 and infiltrated at 1700 ℃ for 2 h.

[0075] In this comparative example, the carbon-ceramic composite material prepared from short-cut carbon fibers has a density of 1.67 g / cm³, a hardness of 68 HSD, and a compressive strength of 116 MPa. The average coefficient of friction is 0.22, and the coefficient of friction stability is 0.63. Compared with the example using mesophase pitch, the material density and mechanical properties are significantly reduced, indicating that non-mesophase pitch is not conducive to obtaining a fine and uniform carbonization texture.

[0076] Comparative Example 9

[0077] Mesophase pitch powder (particle size 30–75 μm) and phenolic resin powder (particle size 30–75 μm) were weighed at a ratio of 60 g and 40 g respectively and mixed to obtain a mixed binder. 2 g of nano-sized carbon black and 6 g of sodium methylcellulose were dissolved in ethanol and ultrasonically dispersed for 45 minutes to obtain a suspension. The suspension was dried in an oven at 60 °C for 6.5 hours to obtain nano-carbon black (particle size ≤ 100 μm) treated with other dispersants. Subsequently, 100 g of the mixed binder was mixed with 2 g of the nano-carbon black and placed in a vibrating crusher, and crushed for 10 minutes to obtain a carbon black-reinforced mixed binder (particle size ≤ 100 μm).

[0078] 100 g of the mixed binder and 100 g of 6.5 mm long carbon fiber were weighed and mixed in a roller mixer for 1.5 h to obtain pressed powder. The pressed powder was poured into a mold heated to 150 °C and pressed under 8 MPa pressure for 20 minutes to obtain a compact. The compact was calcined in a calcining furnace at 1000 °C in a nitrogen atmosphere for 3 h to obtain a calcined body with a density of 1.01 g / cm³. The calcined body was buried in a graphite crucible with Si powder at a mass ratio of 1.8:1 and infiltrated at 1700 °C for 2 h.

[0079] In this comparative example, the carbon-ceramic composite material prepared from short-cut carbon fibers has a density of 1.69 g / cm³, a hardness of 71 HSD, and a compressive strength of 129 MPa. The average coefficient of friction is 0.29, and the coefficient of friction stability is 0.55. Compared with the example using sodium dodecyl sulfonate dispersant, the material density, hardness, and compressive strength are significantly reduced, and the coefficient of friction fluctuates more, indicating that other dispersants are difficult to effectively prevent the agglomeration of nano-carbon black, which is not conducive to improving the overall performance of the material.

[0080] .

Claims

1. A short carbon fiber-reinforced carbon ceramic composite material, characterized by: It is prepared by the following steps: Step one mixed binder preparation Mix the mesophase pitch powder and the resin powder in a mass ratio of 5-7:3-5 to obtain a mixed binder; Step two dispersion of the reinforcing phase Use nanoscale carbon black as the reinforcing phase, and dissolve sodium dodecyl sulfonate in acetone in a mass ratio of 1:1-5, and then uniformly disperse by ultrasonic to obtain a suspension; dry the suspension to obtain modified nanoscale carbon black; then mix the mixed binder obtained in step one and the modified carbon black in a mass ratio of 100:1-4, and crush to obtain a mixed binder reinforced by modified carbon black; Step three powder preparation Mix the mixed binder reinforced by modified carbon black and the chopped carbon fiber in a mass ratio of 40-60:40-60 to obtain a powder; The length of the chopped carbon fiber is 5-8 mm; Step four hot-pressing molding Pour the powder into a mold heated to 100-200 degrees Celsius, and hot-press at 5-10 MPa to form a block; Step five carbonization Place the hot-pressed block in a calcination furnace, and carbonize at 950-1050 degrees Celsius in a protective atmosphere for at least 3 hours to obtain a calcined body; Step six reaction infiltration Place the calcined block in a graphite crucible, weigh Si powder in a ratio of 1.5-2.0:1 to the mass of the block, and fill it into the graphite crucible, seal the crucible, and place it in a infiltration furnace, and infiltrate at 1600-1800 degrees Celsius for at least 1 hour to obtain a short carbon fiber reinforced carbon ceramic composite material.

2. The short carbon fiber reinforced carbon-ceramic composite material according to claim 1, characterized in that: The particle size of the mesophase pitch powder is 15-100 microns, and the particle size of the resin powder is 15-100 microns; the resin is selected from at least one of phenolic resin, epoxy resin, and furan resin.

3. The short carbon fiber reinforced carbon-ceramic composite material according to claim 1, characterized in that: In step one, the mass ratio of the mesophase pitch powder to the resin powder is preferably 5.5-6.5:3.5-4.5, and further preferably 6:

4.

4. The short carbon fiber reinforced carbon-ceramic composite material of claim 1, wherein: In step two, nanoscale carbon black is used as the reinforcing phase, and sodium dodecyl sulfonate is used as the dispersant, which is dissolved in acetone in a mass ratio of 1:1-4, and then dispersed by ultrasonic for 30-60 minutes to obtain a suspension. Dry the suspension in an oven at 50-70 degrees Celsius for 5-8 hours to obtain modified nanoscale carbon black.

5. The short carbon fiber reinforced carbon-ceramic composite material of claim 1, wherein: The mass ratio of nanoscale carbon black to sodium dodecyl sulfonate is 2:4.5-5.

5.

6. The short carbon fiber reinforced carbon-ceramic composite material of claim 1, wherein: In step two, the mixed binder and the modified carbon black are mixed and crushed in a mass ratio of 100:1-4 to obtain a mixed binder reinforced by modified carbon black with a particle size of less than or equal to 100 microns.

7. The short carbon fiber reinforced carbon-ceramic composite material of claim 1, wherein: In step two, the mass ratio of the mixed binder to the modified carbon black is 100:1.5-2.

5.

8. The short carbon fiber reinforced carbon-ceramic composite material of claim 1, wherein: In step three, during the preparation of the powder, the mass ratio of the mixed binder reinforced by modified carbon black to the chopped carbon fiber is 45-55:45-55.

9. The short carbon fiber reinforced carbon-ceramic composite material of claim 1, wherein: In step three, mix in a drum mixer for 1-2 hours to obtain the powder.

10. The short carbon fiber reinforced carbon-ceramic composite material of claim 1, wherein: In step three, the length of the chopped carbon fiber is 6-7 mm.

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