A high-performance carbon ceramic material and its preparation method

Abstract

This invention relates to the field of composite material technology, specifically to a high-performance carbon ceramic material and its preparation method, comprising a carbon fiber matrix; pyrolytic carbon filling and coating the carbon fiber matrix; and a reinforcing ceramic phase dispersed in the pyrolytic carbon, wherein the reinforcing ceramic phase comprises boron carbide and silicon carbide. The carbon ceramic material prepared by this invention has good mechanical properties and wear resistance.

Description

Technical Field

[0001] This invention relates to the field of composite materials technology, specifically to a high-performance carbon ceramic material and its preparation method. Background Technology

[0002] Carbon-ceramic composites are a new type of ceramic material that has been gradually developed since the 1980s. They include carbon fiber (or whisker) toughened (or reinforced) ceramic matrix composites, carbon particle dispersion reinforced ceramic matrix composites, in-situ grown ceramic composites, graded functional composite ceramics, and nano-ceramic composites.

[0003] While existing carbon-ceramic composite materials have good wear resistance, they generally have low toughness and are prone to deformation and fracture when subjected to large external forces. Summary of the Invention

[0004] Purpose of the invention: To address the above-mentioned technical problems, this invention proposes a high-performance carbon ceramic material and its preparation method.

[0005] The technical solution adopted is as follows:

[0006] A high-performance carbon ceramic material, comprising a carbon fiber matrix;

[0007] Pyrolytic carbon fills and coats the carbon fiber matrix;

[0008] and the reinforcing ceramic phase dispersed in the pyrolytic carbon;

[0009] The reinforced ceramic phase includes boron carbide and silicon carbide.

[0010] This invention also provides a method for preparing high-performance carbon ceramic materials, as detailed below:

[0011] S1: A polyaniline transition layer and a polysilazane precursor layer are formed on the surface of carbon fiber cloth, and then heated at 1400-1500℃ for 1-4 hours for pyrolysis.

[0012] S2: Impregnate carbon fiber cloth with organic resin solution and heat to cure it. Repeat this process several times to obtain a sheet.

[0013] S3: The sheet material is stacked in a mold and hot-pressed to form a blank. The temperature during hot pressing is 600-800℃ and the pressure is 5-15MPa.

[0014] S4: Heat the billet to 1500-1600℃ and sinter for 1-4 hours, then alternately deposit pyrolytic carbon and boron carbide in the vapor phase multiple times.

[0015] Furthermore, S1 also includes a high-temperature oxidation treatment of carbon fiber cloth.

[0016] Furthermore, the specific operation of S1 is as follows:

[0017] Carbon fiber cloth is heated to 400-450℃ in air and kept at that temperature for 30-60 minutes for oxidation treatment. Then it is ultrasonically cleaned with acetone, washed with water, and dried. It is then immersed in a polyaniline solution and dried to form a polyaniline transition layer. Finally, it is immersed in a polysilazane solution and dried to form a polysilazane precursor layer.

[0018] Furthermore, the polysilazane solution comprises polysilazane, silicon powder, and solvent in a weight ratio of 3-9:1-3:90-110.

[0019] Further, the solvent is any one or a combination of propylene glycol methyl ether acetate, butyl acetate, amyl acetate, methyl isobutyl ketone, and methyl amyl ketone.

[0020] Furthermore, the organic resin solution in S2 is an epoxy-modified phenolic resin solution.

[0021] Furthermore, the preparation method of the epoxy-modified phenolic resin solution is as follows:

[0022] Add phenol and polyvinyl alcohol to sodium hydroxide solution, heat to 85-95℃ and stir until homogeneous, add formaldehyde, continue stirring for 120-180 min, add 1,4-butanediol diglycidyl ether and continue stirring for 30-60 min, then return to room temperature.

[0023] Furthermore, propane is used as the gas source during the vapor-phase deposition of pyrolyzed carbon, and the temperature is 1000-1200℃.

[0024] Furthermore, during the vapor deposition of boron carbide, the gas source is methane, hydrogen, and boron trichloride, and the temperature is 1000-1200℃.

[0025] The beneficial effects of this invention are:

[0026] This invention provides a high-performance carbon ceramic material, in which a polyaniline transition layer and a polysilazane precursor layer are formed on carbon fibers during preparation. The polyaniline can improve the bonding strength between carbon fibers and polysilazane and increase the amount of polysilazane adhesion.

[0027] Polyaniline and polysilazane are decomposed by heating to generate a large amount of carbonaceous and silicon raw materials. In the carbothermic reduction reaction system composed of carbonaceous and silicon raw materials and silicon powder, a large amount of intermediate reactants SiO and CO are generated. SiO reacts with C to generate SiC crystal nuclei. Silicon powder also reacts directly with C to generate some SiC crystal nuclei. SiO and CO also react to generate a large amount of SiC. A large number of SiC whiskers are generated in situ between the carbon fibers. SiC whiskers can not only improve the mechanical strength of the material, but also increase the loading of organic resin to a certain extent.

[0028] Epoxy-modified phenolic resin reacts the unreacted phenolic hydroxyl groups with epoxy groups to form ether bonds. Under the same number of impregnations, the loading of organic resin is increased, the crosslinking density is improved, the char residue is increased, and the thermal deformation under decomposition conditions is small.

[0029] Alternating deposition of pyrolytic carbon and boron carbide can form a weak interfacial bond with the carbon ceramic material matrix, which promotes the toughening mechanism such as fiber pull-out during crack propagation and improves the structural mechanical strength.

[0030] After testing, the high-performance carbon ceramic material prepared by this invention has good mechanical properties and wear resistance. Attached Figure Description

[0031] Figure 1 This is a SEM image of the in-situ generated SiC whiskers in Example 1;

[0032] Figure 2 This is a SEM image of the cross-section of the carbon-ceramic material prepared in Example 1. Detailed Implementation

[0033] Unless otherwise specified in the examples, the conditions were performed under standard conditions or as recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products. Techniques not mentioned in this invention refer to existing technologies. Unless otherwise specified, the following examples and comparative examples are parallel experiments, using the same processing steps and parameters.

[0034] Example 1:

[0035] A method for preparing high-performance carbon ceramic materials:

[0036] S1: Carbon fiber cloth (thickness 0.111mm, 200g / m²) 2 The carbon fiber was heated to 450℃ in air and kept at that temperature for 40 minutes to remove the sizing agent from the surface and leave etching marks and active groups. Then, it was added to acetone and ultrasonically cleaned for 15 minutes. After cleaning, it was rinsed with distilled water and dried. A 5 wt% polyaniline DMF solution was prepared, and the carbon fiber was placed in it and immersed for 10 minutes. After being removed, it was placed in an oven and dried at 80℃ for 8 hours to form a polyaniline transition layer. Then, it was immersed in a polysilazane solution for 10 minutes and dried at 120℃ for 8 hours to form a polysilazane precursor layer. The polysilazane solution included polysilazane, silicon powder and butyl acetate in a weight ratio of 5:2:93. Then, it was heated to 1450℃ at a rate of 20℃ / min and heated for pyrolysis for 2 hours.

[0037] S2: Add 941.1g of phenol and 15g of polyvinyl alcohol to 50L of 2.5wt% sodium hydroxide solution, heat to 90℃ and stir evenly. Add 1216.2g of 37wt% formaldehyde and continue stirring for 160min. Add 505.6g of 1,4-butanediol diglycidyl ether and continue stirring for 40min. Return to room temperature to obtain epoxy-modified phenolic resin solution. Vacuum impregnate carbon fiber cloth in it for 30min, remove it and heat to 200℃ for 2h. Repeat the vacuum impregnation-heat curing operation twice to obtain sheet material.

[0038] S3: The above-mentioned sheets are stacked in parallel in a mold and hot-pressed to form a blank. The thickness of the blank is controlled by controlling the number of stacked sheets. The temperature during hot pressing is 800℃ and the pressure is 7.5MPa.

[0039] S4: After sintering the above-mentioned green body at 1600℃ for 2 hours, pyrolytic carbon and boron carbide are deposited alternately in the vapor phase. The vapor phase deposition is carried out in the YHGYL-CJL-CVD chemical vapor deposition equipment of Yuanhang. When depositing pyrolytic carbon, the gas source is propane and the dilution gas is nitrogen. The flow ratio of propane to nitrogen is 120 ml / min: 30 ml / min, the temperature is 1200℃, and the deposition time is 3 hours. When depositing boron carbide, the gas source is methane, hydrogen, and boron trichloride. The flow ratio of methane, hydrogen, and boron trichloride is 20 ml / min: 35 ml / min: 100 ml / min, the temperature is 1200℃, and the deposition time is 3 hours. Pyrolytic carbon and boron carbide are deposited alternately twice.

[0040] Example 2:

[0041] It is basically the same as Example 1, except that the vacuum impregnation-heat curing operation is repeated three times in S2.

[0042] Example 3:

[0043] It is basically the same as Example 1, except that the vacuum impregnation-heat curing operation is repeated four times in S2.

[0044] Comparative Example 1:

[0045] It is basically the same as Example 1, except that it does not contain a polyaniline transition layer.

[0046] Comparative Example 2:

[0047] It is basically the same as Example 1, except that it does not contain a polysilazane precursor layer.

[0048] Comparative Example 3:

[0049] The method is basically the same as in Example 1, except that a commercially available water-soluble phenolic resin solution of the same concentration is used instead of the epoxy-modified phenolic resin solution.

[0050] Comparative Example 4:

[0051] It is basically the same as Example 1, except that it does not contain vapor-deposited pyrolytic carbon.

[0052] Comparative Example 5:

[0053] It is basically the same as Example 1, except that it does not contain vapor-deposited boron carbide.

[0054] Performance testing:

[0055] The high-performance carbon ceramic materials prepared in Examples 1-3 and Comparative Examples 1-5 of this invention were used as samples for performance testing.

[0056] The specific testing method is as follows:

[0057] The density of the sample was tested using the Archimedes displacement method.

[0058] The bending strength and fracture toughness of the specimens were tested on an electronic universal testing machine. The loading speed was 0.5 mm / min, the specimen size was 30 mm × 5 mm × 4 mm, and the fixed span was 20 mm.

[0059] Testing machine model: MM-200; Sample size: 7mm×7mm×30mm; Friction type: sliding dry friction; The material of the grinding pair is 9Cr18, the size is φ50mm×10mm, the surface roughness is 1.6, the test conditions are: rotation speed 200r / min, pressure 250N, running time 10h;

[0060] The test results are shown in Table 1.

[0061] Table 1:

[0062]

[0063] As shown in Table 1 above, the carbon ceramic material prepared by this invention has good mechanical properties and excellent wear resistance.

[0064] The comparison of Examples 1-3 shows that the loading of phenolic resin reaches saturation after three repeated vacuum impregnation-heat curing operations, and further increasing the number of operations has little effect on improving various properties.

[0065] In Comparative Example 1, the absence of a polyaniline transition layer resulted in a decrease in the bonding performance between the polysilazane precursor layer and the carbon fiber, a reduction in the amount of adhesion, and a decrease in the number of in-situ generated silicon carbide whiskers, which in turn led to a decrease in a series of indicators.

[0066] In Comparative Example 2, due to the absence of a polysilazane precursor layer, silicon carbide whiskers could not be generated in situ, leading to a decrease in a series of indicators.

[0067] In Comparative Example 3, the crosslinking density of commercially available water-soluble phenolic resin is inferior to that of the epoxy-modified phenolic resin prepared in this invention. Under the same number of impregnations, the resin loading is reduced, which in turn leads to a decrease in density and a decline in mechanical properties.

[0068] In Comparative Examples 4-5, the lack of vapor-deposited pyrolytic carbon and boron carbide prevented the filling of pores within the material, thus hindering the toughening mechanism of pyrolytic carbon and boron carbide and leading to a decline in a series of indicators.

[0069] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A high-performance carbon ceramic material, characterized in that, Including carbon fiber matrix; Pyrolytic carbon fills and coats the carbon fiber matrix; and the reinforcing ceramic phase dispersed in the pyrolytic carbon; The reinforced ceramic phase includes boron carbide and silicon carbide; The preparation method of the above-mentioned high-performance carbon ceramic materials is as follows: S1: Heat the carbon fiber cloth to 400-450℃ in air and keep it at that temperature for 30-60 minutes for oxidation treatment. Then, clean it with acetone by ultrasonication, wash it with water, and dry it. Then, immerse it in a polyaniline solution and dry it to form a polyaniline transition layer. Then, immerse it in a polysilazane solution and dry it to form a polysilazane precursor layer. Heat it at 1400-1500℃ for 1-4 hours for pyrolysis. S2: Impregnate carbon fiber cloth with organic resin solution and heat to cure it. Repeat this process several times to obtain a sheet. S3: The sheet material is stacked in a mold and hot-pressed to form a blank. The temperature during hot pressing is 600-800℃ and the pressure is 5-15MPa. S4: Heat the billet to 1500-1600℃ and sinter for 1-4 hours, then alternately deposit pyrolytic carbon and boron carbide in the vapor phase multiple times. The polysilazane solution comprises polysilazane, silicon powder, and solvent in a weight ratio of 3-9:1-3:90-110; The organic resin solution in S2 is an epoxy-modified phenolic resin solution.

2. The high-performance carbon ceramic material as described in claim 1, characterized in that, The solvent is any one or a combination of propylene glycol methyl ether acetate, butyl acetate, amyl acetate, methyl isobutyl ketone, and methyl amyl ketone.

3. The high-performance carbon ceramic material as described in claim 1, characterized in that, The preparation method of the epoxy-modified phenolic resin solution is as follows: Add phenol and polyvinyl alcohol to sodium hydroxide solution, heat to 85-95℃ and stir until homogeneous, add formaldehyde, continue stirring for 120-180 min, add 1,4-butanediol diglycidyl ether and continue stirring for 30-60 min, then return to room temperature.

4. The high-performance carbon ceramic material as described in claim 1, characterized in that, During the vapor phase deposition of pyrolyzed carbon, propane is used as the gas source, and the temperature is 1000-1200℃.

5. The high-performance carbon ceramic material as described in claim 1, characterized in that, When depositing boron carbide in the vapor phase, the gas source is methane, hydrogen and boron trichloride, and the temperature is 1000-1200℃.

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