Silicon carbide reinforced graphite material, method for producing the same, and use thereof

Abstract

The application relates to the field of material science and engineering, and discloses a silicon carbide reinforced graphite material and a preparation method and application thereof. The preparation method of the silicon carbide reinforced graphite material comprises the steps of graphite pretreatment, polysilazane impregnation, high-temperature reaction, cooling and post-treatment. The silicon carbide reinforced graphite material is successfully prepared through the method of high-vacuum pretreatment, polysilazane impregnation and high-temperature reaction, and the hardness, oxidation resistance and impact resistance of the graphite are significantly improved. The method has the advantages of simple process, low cost and significant performance improvement, and has a wide application prospect.

Description

Technical Field

[0001] This invention relates to the field of materials science and engineering, and more specifically, to a silicon carbide reinforced graphite material, its preparation method, and its application. Background Technology

[0002] Graphite materials are widely used in metallurgy, chemical industry, machinery, electronics, and aerospace due to their excellent electrical conductivity, thermal conductivity, and chemical stability. However, graphite's relatively low hardness, oxidation resistance, and impact resistance limit its application in extreme environments.

[0003] To improve the overall performance of graphite materials, existing technologies typically employ surface coatings or composite materials. Surface coatings involve applying an antioxidant coating to the graphite surface. While this improves oxidation resistance, the coating's adhesion to the substrate is weak, making it prone to peeling, and its improvement on overall mechanical properties is limited. Composite materials involve combining graphite with reinforcing particles through powder metallurgy, hot pressing, or sintering. While this can increase the material's hardness and strength, the process is complex, energy-intensive, and the introduced reinforcing phase is often unevenly distributed, leading to internal defects and affecting its thermal conductivity, electrical conductivity, and structural integrity.

[0004] Therefore, developing a method that is simple in process, low in cost, and can significantly improve the overall performance of graphite materials has important application value. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing graphite materials in terms of hardness, oxidation resistance, and impact resistance, as well as the problems of easy coating peeling, complex composite material processing, and uneven distribution of reinforcing phases in existing reinforcement methods. Therefore, this invention provides a method for preparing silicon carbide-reinforced graphite materials through polysilazane impregnation and high-temperature reaction, which improves the hardness, oxidation resistance, and impact resistance of graphite materials.

[0006] To achieve the above-mentioned objectives, the present invention employs the following technical solution:

[0007] In a first aspect, the present invention provides a method for preparing a silicon carbide reinforced graphite material, comprising the following steps:

[0008] Step 1, graphite pretreatment;

[0009] The porous graphite matrix is ​​placed in a high vacuum environment to remove surface and internal impurities and gases;

[0010] Step 2, impregnation with polysilazane;

[0011] The pretreated graphite material is impregnated in a polysilazane solution under vacuum or pressure assistance.

[0012] Step 3, high-temperature reaction;

[0013] The impregnated graphite matrix is ​​subjected to a high-temperature reaction under an inert atmosphere, which causes the polysilazane to crack and react with the graphite matrix to generate silicon carbide.

[0014] Step 4, cooling and post-processing;

[0015] After the reaction is complete, the material is cooled to room temperature, and the surface is polished and cleaned to obtain silicon carbide reinforced graphite material.

[0016] Furthermore, in step 1, the vacuum level of the high vacuum environment is not less than 10. -3 Pa, and the holding time shall not be less than 12 hours.

[0017] Furthermore, the porous graphite matrix has a porosity of 20-40% and a pore size distribution of 1-10 μm.

[0018] Furthermore, in step 2, the mass concentration of the polysilazane solution is 10-30%; and the impregnation time is 2-4 hours.

[0019] Furthermore, in step 2, the number of immersions is 1 to 3, and a pre-drying treatment is performed after each immersion. The drying temperature is 80 to 120°C, and the drying time is 1 to 2 hours.

[0020] Furthermore, in step 3, the inert atmosphere is nitrogen, argon, or helium;

[0021] The inert atmosphere gas flow rate is 0.5~2L / min.

[0022] Furthermore, in step 3, the high-temperature reaction includes:

[0023] The temperature was increased to 800-1200℃ at a rate of 5-10℃ / min for the first stage of reaction, and the reaction time was 1-3 hours.

[0024] The second stage reaction was carried out by raising the temperature to 1400-1800℃ at a rate of 3-5℃ / min, and the reaction time was 2-4 hours.

[0025] Furthermore, in step 4, the material is cooled to room temperature at a cooling rate of 5~10℃ / min;

[0026] Surface polishing is performed using diamond grinding wheels or silicon carbide sandpaper, with a polishing precision of Ra≤0.8μm.

[0027] Secondly, the present invention provides a silicon carbide reinforced graphite material, which is prepared by the method described above.

[0028] Thirdly, the present invention provides the application of silicon carbide reinforced graphite materials prepared by the method in the fields of metallurgy, chemical industry, machinery, electronics and aerospace.

[0029] In summary, the present invention has the following beneficial effects:

[0030] This invention successfully prepared silicon carbide-reinforced graphite materials through high-vacuum pretreatment, polysilazane impregnation, and high-temperature reaction, significantly improving the hardness, oxidation resistance, and impact resistance of graphite. This method is simple, low-cost, and provides significant performance improvements, showing broad application prospects. Detailed Implementation

[0031] The technical solutions and effects of the present invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely for explaining the invention and are not intended to limit the invention.

[0032] Example 1

[0033] This embodiment provides a silicon carbide reinforced graphite material, which is prepared through the following steps:

[0034] Step 1, Graphite Pretreatment

[0035] The porous graphite matrix is ​​placed in a high vacuum environment to remove surface and internal impurities and gases;

[0036] Among them, the vacuum level of the high vacuum environment is not less than 10. -3 Pa, and the holding time shall not be less than 12 hours.

[0037] The porous graphite matrix has a porosity of 20% and a pore size distribution of 1~10μm.

[0038] Step 2, impregnation with polysilazane

[0039] The pretreated graphite material is impregnated in a polysilazane solution under vacuum or pressure.

[0040] The polysilazane solution has a mass concentration of 10%; the impregnation time is 4 hours.

[0041] The immersion was performed once, followed by pre-drying at 80℃ for 2 hours.

[0042] Step 3, high-temperature reaction

[0043] The impregnated graphite matrix is ​​subjected to a high-temperature reaction under an inert atmosphere, which causes the polysilazane to crack and react with the graphite matrix to generate silicon carbide.

[0044] The inert atmosphere is nitrogen.

[0045] The inert atmosphere gas flow rate is 0.5 L / min;

[0046] High-temperature reactions include:

[0047] The temperature was increased to 800℃ at a rate of 5℃ / min for the first stage of reaction, and the reaction time was 3h.

[0048] The second stage reaction was carried out by heating to 1400℃ at a rate of 3℃ / min for 4 hours.

[0049] Step 4, Cooling and Post-processing

[0050] After the reaction is complete, the material is cooled to room temperature, and the surface is polished and cleaned to obtain silicon carbide reinforced graphite material.

[0051] The material was cooled to room temperature at a rate of 5°C / min.

[0052] Surface polishing is performed using diamond grinding wheels or silicon carbide sandpaper, with a polishing precision of Ra≤0.8μm.

[0053] Example 2

[0054] This embodiment provides a silicon carbide reinforced graphite material, which is prepared through the following steps:

[0055] Step 1, Graphite Pretreatment

[0056] The porous graphite matrix is ​​placed in a high vacuum environment to remove surface and internal impurities and gases.

[0057] Among them, the vacuum level of the high vacuum environment is not less than 10. -3 Pa, the retention time shall not be less than 12 hours;

[0058] The porous graphite matrix has a porosity of 30% and a pore size distribution of 1~10μm.

[0059] Step 2, impregnation with polysilazane

[0060] The pretreated graphite material is impregnated in a polysilazane solution under vacuum or pressure.

[0061] The polysilazane solution has a mass concentration of 10%; the impregnation time is 4 hours.

[0062] The immersion was performed once, followed by pre-drying at 80℃ for 2 hours.

[0063] Step 3, high-temperature reaction

[0064] The impregnated graphite matrix is ​​subjected to a high-temperature reaction under an inert atmosphere, which causes the polysilazane to crack and react with the graphite matrix to generate silicon carbide.

[0065] The inert atmosphere is nitrogen.

[0066] The inert atmosphere gas flow rate is 0.5 L / min.

[0067] High-temperature reactions include:

[0068] The temperature was increased to 800℃ at a rate of 5℃ / min for the first stage of reaction, and the reaction time was 3h.

[0069] The second stage reaction was carried out by heating to 1400℃ at a rate of 3℃ / min for 4 hours.

[0070] Step 4, Cooling and Post-processing

[0071] After the reaction is complete, the material is cooled to room temperature, and the surface is polished and cleaned to obtain silicon carbide reinforced graphite material.

[0072] The material was cooled to room temperature at a rate of 5°C / min.

[0073] Surface polishing is performed using diamond grinding wheels or silicon carbide sandpaper, with a polishing precision of Ra≤0.8μm.

[0074] Example 3

[0075] This embodiment provides a silicon carbide reinforced graphite material, which is prepared through the following steps:

[0076] Step 1, Graphite Pretreatment

[0077] The porous graphite matrix is ​​placed in a high vacuum environment to remove surface and internal impurities and gases.

[0078] Among them, the vacuum level of the high vacuum environment is not less than 10. -3 Pa, the retention time shall not be less than 12 hours;

[0079] The porous graphite matrix has a porosity of 40% and a pore size distribution of 1~10μm.

[0080] Step 2, impregnation with polysilazane

[0081] The pretreated graphite material is impregnated in a polysilazane solution under vacuum or pressure.

[0082] The polysilazane solution has a mass concentration of 10%; the impregnation time is 4 hours.

[0083] The immersion was performed once, followed by pre-drying at 80℃ for 2 hours.

[0084] Step 3, high-temperature reaction

[0085] The impregnated graphite matrix is ​​subjected to a high-temperature reaction under an inert atmosphere, which causes the polysilazane to crack and react with the graphite matrix to generate silicon carbide.

[0086] The inert atmosphere is nitrogen.

[0087] The inert atmosphere gas flow rate is 0.5 L / min.

[0088] High-temperature reactions include:

[0089] The temperature was increased to 800℃ at a rate of 5℃ / min for the first stage of reaction, and the reaction time was 3h.

[0090] The second stage reaction was carried out by heating to 1400℃ at a rate of 3℃ / min for 4 hours.

[0091] Step 4, Cooling and Post-processing

[0092] After the reaction is complete, the material is cooled to room temperature, and the surface is polished and cleaned to obtain silicon carbide reinforced graphite material.

[0093] The material was cooled to room temperature at a rate of 5°C / min.

[0094] Surface polishing is performed using diamond grinding wheels or silicon carbide sandpaper, with a polishing precision of Ra≤0.8μm.

[0095] Example 4

[0096] This embodiment provides a silicon carbide reinforced graphite material, which is prepared through the following steps:

[0097] Step 1, Graphite Pretreatment

[0098] The porous graphite matrix is ​​placed in a high vacuum environment to remove surface and internal impurities and gases.

[0099] Among them, the vacuum level of the high vacuum environment is not less than 10. -3 Pa, the retention time shall not be less than 12 hours;

[0100] The porous graphite matrix has a porosity of 20% and a pore size distribution of 1~10μm.

[0101] Step 2, impregnation with polysilazane

[0102] The pretreated graphite material is impregnated in a polysilazane solution under vacuum or pressure.

[0103] The polysilazane solution has a mass concentration of 10%; the impregnation time is 4 hours.

[0104] The immersion was performed once, followed by pre-drying at 80℃ for 2 hours.

[0105] Step 3, high-temperature reaction

[0106] The impregnated graphite matrix is ​​subjected to a high-temperature reaction under an inert atmosphere, which causes the polysilazane to crack and react with the graphite matrix to generate silicon carbide.

[0107] The inert atmosphere is nitrogen.

[0108] The inert atmosphere gas flow rate is 0.5 L / min.

[0109] High-temperature reactions include:

[0110] The temperature was increased to 800℃ at a rate of 5℃ / min for the first stage of reaction, and the reaction time was 3h.

[0111] The second stage reaction was carried out by heating to 1400℃ at a rate of 3℃ / min for 4 hours.

[0112] Step 4, Cooling and Post-processing

[0113] After the reaction is complete, the material is cooled to room temperature, and the surface is polished and cleaned to obtain silicon carbide reinforced graphite material.

[0114] The material was cooled to room temperature at a rate of 5°C / min.

[0115] Surface polishing is performed using diamond grinding wheels or silicon carbide sandpaper, with a polishing precision of Ra≤0.8μm.

[0116] Example 5

[0117] This embodiment provides a silicon carbide reinforced graphite material, which is prepared through the following steps:

[0118] Step 1, Graphite Pretreatment

[0119] The porous graphite matrix is ​​placed in a high vacuum environment to remove surface and internal impurities and gases.

[0120] Among them, the vacuum level of the high vacuum environment is not less than 10. -3 Pa, the retention time shall not be less than 12 hours;

[0121] The porous graphite matrix has a porosity of 20% and a pore size distribution of 1~10μm.

[0122] Step 2, impregnation with polysilazane

[0123] The pretreated graphite material is impregnated in a polysilazane solution under vacuum or pressure.

[0124] The polysilazane solution has a mass concentration of 20%; the impregnation time is 4 hours.

[0125] The immersion was performed once, followed by pre-drying at 80℃ for 2 hours.

[0126] Step 3, high-temperature reaction

[0127] The impregnated graphite matrix is ​​subjected to a high-temperature reaction under an inert atmosphere, which causes the polysilazane to crack and react with the graphite matrix to generate silicon carbide.

[0128] The inert atmosphere is nitrogen.

[0129] The inert atmosphere gas flow rate is 0.5 L / min.

[0130] High-temperature reactions include:

[0131] The temperature was increased to 800℃ at a rate of 5℃ / min for the first stage of reaction, and the reaction time was 3h.

[0132] The second stage reaction was carried out by heating to 1400℃ at a rate of 3℃ / min for 4 hours.

[0133] Step 4, Cooling and Post-processing

[0134] After the reaction is complete, the material is cooled to room temperature, and the surface is polished and cleaned to obtain silicon carbide reinforced graphite material.

[0135] The material was cooled to room temperature at a rate of 5°C / min.

[0136] Surface polishing is performed using diamond grinding wheels or silicon carbide sandpaper, with a polishing precision of Ra≤0.8μm.

[0137] Example 6

[0138] This embodiment provides a silicon carbide reinforced graphite material, which is prepared through the following steps:

[0139] Step 1, Graphite Pretreatment

[0140] The porous graphite matrix is ​​placed in a high vacuum environment to remove surface and internal impurities and gases.

[0141] Among them, the vacuum level of the high vacuum environment is not less than 10. -3 Pa, and the holding time shall not be less than 12 hours.

[0142] The porous graphite matrix has a porosity of 20% and a pore size distribution of 1~10μm.

[0143] Step 2, impregnation with polysilazane

[0144] The pretreated graphite material is impregnated in a polysilazane solution under vacuum or pressure.

[0145] The polysilazane solution has a mass concentration of 30%; the impregnation time is 4 hours.

[0146] The immersion was performed once, followed by pre-drying at 80℃ for 2 hours.

[0147] Step 3, high-temperature reaction

[0148] The impregnated graphite matrix is ​​subjected to a high-temperature reaction under an inert atmosphere, which causes the polysilazane to crack and react with the graphite matrix to generate silicon carbide.

[0149] The inert atmosphere is nitrogen.

[0150] The inert atmosphere gas flow rate is 0.5 L / min.

[0151] High-temperature reactions include:

[0152] The temperature was increased to 800℃ at a rate of 5℃ / min for the first stage of reaction, and the reaction time was 3h.

[0153] The second stage reaction was carried out by heating to 1400℃ at a rate of 3℃ / min for 4 hours.

[0154] Step 4, Cooling and Post-processing

[0155] After the reaction is complete, the material is cooled to room temperature, and the surface is polished and cleaned to obtain silicon carbide reinforced graphite material.

[0156] The material was cooled to room temperature at a rate of 5°C / min.

[0157] Surface polishing is performed using diamond grinding wheels or silicon carbide sandpaper, with a polishing precision of Ra≤0.8μm.

[0158] Example 7

[0159] This embodiment provides a silicon carbide reinforced graphite material, which is prepared through the following steps:

[0160] Step 1, Graphite Pretreatment

[0161] The porous graphite matrix is ​​placed in a high vacuum environment to remove surface and internal impurities and gases.

[0162] Among them, the vacuum level of the high vacuum environment is not less than 10. -3Pa, and the holding time shall not be less than 12 hours.

[0163] The porous graphite matrix has a porosity of 20% and a pore size distribution of 1~10μm.

[0164] Step 2, impregnation with polysilazane

[0165] The pretreated graphite material is impregnated in a polysilazane solution under vacuum or pressure.

[0166] The polysilazane solution has a mass concentration of 10% and the impregnation time is 4 hours.

[0167] The immersion was performed three times, followed by pre-drying at 120°C for 1 hour.

[0168] Step 3, high-temperature reaction

[0169] The impregnated graphite matrix is ​​subjected to a high-temperature reaction under an inert atmosphere, which causes the polysilazane to crack and react with the graphite matrix to generate silicon carbide.

[0170] The inert atmosphere is nitrogen.

[0171] The inert atmosphere gas flow rate is 0.5 L / min.

[0172] High-temperature reactions include:

[0173] The temperature was increased to 800℃ at a rate of 5℃ / min for the first stage of reaction, and the reaction time was 3h.

[0174] The second stage reaction was carried out by heating to 1400℃ at a rate of 3℃ / min for 4 hours.

[0175] Step 4, Cooling and Post-processing

[0176] After the reaction is complete, the material is cooled to room temperature, and the surface is polished and cleaned to obtain silicon carbide reinforced graphite material.

[0177] The material was cooled to room temperature at a rate of 5°C / min.

[0178] Surface polishing is performed using diamond grinding wheels or silicon carbide sandpaper, with a polishing precision of Ra≤0.8μm.

[0179] Example 8

[0180] This embodiment provides a silicon carbide reinforced graphite material, which is prepared through the following steps:

[0181] Step 1, Graphite Pretreatment

[0182] The porous graphite matrix is ​​placed in a high vacuum environment to remove surface and internal impurities and gases.

[0183] Among them, the vacuum level of the high vacuum environment is not less than 10. -3 Pa, the retention time shall not be less than 12 hours;

[0184] The porous graphite matrix has a porosity of 20% and a pore size distribution of 1~10μm.

[0185] Step 2, impregnation with polysilazane

[0186] The pretreated graphite material is impregnated in a polysilazane solution under vacuum or pressure.

[0187] The polysilazane solution has a mass concentration of 10%; the impregnation time is 4 hours.

[0188] The immersion was performed once, followed by pre-drying at 80℃ for 2 hours.

[0189] Step 3, high-temperature reaction

[0190] The impregnated graphite matrix is ​​subjected to a high-temperature reaction under an inert atmosphere, which causes the polysilazane to crack and react with the graphite matrix to generate silicon carbide.

[0191] The inert atmosphere is argon.

[0192] The inert atmosphere gas flow rate is 2 L / min.

[0193] High-temperature reactions include:

[0194] The temperature was increased to 800℃ at a rate of 5℃ / min for the first stage of reaction, and the reaction time was 3h.

[0195] The second stage reaction was carried out by heating to 1400℃ at a rate of 3℃ / min for 4 hours.

[0196] Step 4, Cooling and Post-processing

[0197] After the reaction is complete, the material is cooled to room temperature, and the surface is polished and cleaned to obtain silicon carbide reinforced graphite material.

[0198] The material was cooled to room temperature at a rate of 10℃ / min.

[0199] Surface polishing is performed using diamond grinding wheels or silicon carbide sandpaper, with a polishing precision of Ra≤0.8μm.

[0200] Example 9

[0201] This embodiment provides a silicon carbide reinforced graphite material, which is prepared through the following steps:

[0202] Step 1, Graphite Pretreatment

[0203] The porous graphite matrix is ​​placed in a high vacuum environment to remove surface and internal impurities and gases.

[0204] Among them, the vacuum level of the high vacuum environment is not less than 10. -3 Pa, and the holding time shall not be less than 12 hours.

[0205] The porous graphite matrix has a porosity of 20% and a pore size distribution of 1~10μm.

[0206] Step 2, impregnation with polysilazane

[0207] The pretreated graphite material is impregnated in a polysilazane solution under vacuum or pressure.

[0208] The polysilazane solution has a mass concentration of 10% and the impregnation time is 4 hours.

[0209] The immersion was performed once, followed by pre-drying at 80℃ for 2 hours.

[0210] Step 3, high-temperature reaction

[0211] The impregnated graphite matrix is ​​subjected to a high-temperature reaction under an inert atmosphere, which causes the polysilazane to crack and react with the graphite matrix to generate silicon carbide.

[0212] The inert atmosphere is nitrogen.

[0213] The inert atmosphere gas flow rate is 0.5 L / min.

[0214] High-temperature reactions include:

[0215] The temperature was increased to 1200℃ at a rate of 10℃ / min for the first stage of reaction, and the reaction time was 1 hour.

[0216] The second stage reaction was carried out by heating to 1800℃ at a rate of 5℃ / min for 2 hours.

[0217] Step 4, Cooling and Post-processing

[0218] After the reaction is complete, the material is cooled to room temperature, and the surface is polished and cleaned to obtain silicon carbide reinforced graphite material.

[0219] The material was cooled to room temperature at a rate of 5°C / min.

[0220] Surface polishing is performed using diamond grinding wheels or silicon carbide sandpaper, with a polishing precision of Ra≤0.8μm.

[0221] Comparative Example 1

[0222] This comparative example provides a graphite material prepared through the following steps:

[0223] Step 1, graphite pretreatment: The porous graphite matrix is ​​placed in a natural environment without high vacuum treatment; the porosity of the porous graphite matrix is ​​20%, and the pore size distribution is 1~10μm.

[0224] Step 2, direct drying: dry the unimpregnated graphite matrix at 80°C for 2 hours.

[0225] Step 3, high temperature treatment: The dried graphite matrix is ​​heated to 800°C in air at a heating rate of 5°C / min and held at that temperature for 3 hours.

[0226] Step 4, post-cooling treatment: allow the material to cool naturally to room temperature without polishing, and obtain the graphite material for comparison.

[0227] Comparative Example 2

[0228] This comparative example provides a graphite material prepared through the following steps:

[0229] Step 1, Graphite Pretreatment

[0230] The porous graphite matrix is ​​placed in a high vacuum environment to remove surface and internal impurities and gases.

[0231] Among them, the vacuum level of the high vacuum environment is not less than 10. -3 Pa, the retention time shall not be less than 12 hours;

[0232] The porous graphite matrix has a porosity of 20% and a pore size distribution of 1~10μm.

[0233] Step 2, impregnation with polysilazane

[0234] The pretreated graphite material is impregnated in a polysilazane solution under vacuum or pressure.

[0235] The polysilazane solution has a mass concentration of 10%; the impregnation time is 4 hours.

[0236] The immersion was performed once, followed by pre-drying at 80℃ for 2 hours.

[0237] Step 3, high-temperature reaction

[0238] The impregnated graphite matrix is ​​subjected to a high-temperature reaction under an inert atmosphere, which causes the polysilazane to crack and react with the graphite matrix to generate silicon carbide.

[0239] The inert atmosphere is nitrogen.

[0240] The inert atmosphere gas flow rate is 0.5 L / min.

[0241] High-temperature reactions include:

[0242] The temperature was increased to 1400℃ at a rate of 5℃ / min, and the reaction time was 7h.

[0243] Step 4, Cooling and Post-processing

[0244] After the reaction is complete, the material is cooled to room temperature, and the surface is polished and cleaned to obtain silicon carbide reinforced graphite material.

[0245] The material was cooled to room temperature at a rate of 5°C / min.

[0246] Surface polishing is performed using diamond grinding wheels or silicon carbide sandpaper, with a polishing precision of Ra≤0.8μm.

[0247] Performance testing

[0248] The material samples prepared in Examples 1-9 and the material samples in Comparative Examples 1-2 were tested for hardness, oxidation resistance and impact resistance.

[0249] Hardness was tested according to the method in GB / T 4340.1-2024 "Metallic materials - Vickers hardness test - Part 1: Test method";

[0250] Antioxidant properties were tested according to the methods in GB / T 3003-2017 "Refractory Fibers and Products";

[0251] Impact resistance was tested according to the method of ASTM D6110-2017.

[0252] The test results are shown in Table 1:

[0253] Table 1

[0254]

[0255] As shown in Table 1, the silicon carbide reinforced graphite materials prepared in Examples 1-9 are significantly superior to Comparative Examples 1 and 2 in terms of hardness, oxidation resistance, and impact resistance.

[0256] The hardness data shows that the average Vickers hardness HV5 of the examples all exceeded 90, with Example 7 reaching 146±7, while Comparative Example 1 was only 45±2 and Comparative Example 2 was 70±4. This indicates that the hardness of the material was greatly improved after processing such as polysilazane impregnation and high-temperature reaction.

[0257] The antioxidant data show that the mass loss rate of the examples after 10 cycles of oxidation is less than 4%, and Example 7 is the best example with a loss rate as low as 0.9%. In contrast, the mass loss rate of Comparative Example 1 is close to 100%, and that of Comparative Example 2 is 18.9%. This indicates that the silicon carbide reinforced structure can effectively suppress the mass loss of the material under high-temperature oxidation environment and improve its antioxidant stability.

[0258] The impact resistance data show that the average impact toughness of all examples exceeds 0.8 J / cm. 2 In contrast, Comparative Example 1 only has 0.10 J / cm³. 2 Comparative Example 2 has a value of 0.33 J / cm³. 2 .

[0259] In summary, this invention has successfully prepared silicon carbide reinforced graphite materials with excellent comprehensive performance by optimizing graphite pretreatment, polysilazane impregnation parameters, high-temperature reaction conditions, and cooling post-treatment processes.

[0260] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A method for preparing a silicon carbide-reinforced graphite material, characterized in that, Includes the following steps: Step 1, graphite pretreatment; The porous graphite matrix is ​​placed in a high vacuum environment to remove surface and internal impurities and gases; Step 2, impregnation with polysilazane; The pretreated graphite material is impregnated in a polysilazane solution under vacuum or pressure assistance; the mass concentration of the polysilazane solution is 10-30%; the impregnation time is 2-4 hours, the number of impregnations is 1-3 times, and a pre-drying treatment is performed after each impregnation at a temperature of 80-120℃ for 1-2 hours. Step 3, high-temperature reaction; The impregnated graphite matrix is ​​subjected to a high-temperature reaction under an inert atmosphere, causing the polysilazane to crack and react with the graphite matrix to generate silicon carbide; the high-temperature reaction is a two-stage heating reaction: The first stage of the reaction: the temperature is increased to 800-1200℃ at a rate of 5-10℃ / min, and the reaction time is 1-3h; The second stage of the reaction: the temperature is increased to 1400-1800℃ at a rate of 3-5℃ / min, and the reaction time is 2-4h; Step 4, cooling and post-processing; After the reaction is complete, the material is cooled to room temperature, and the surface is polished and cleaned to obtain silicon carbide reinforced graphite material.

2. The method for preparing silicon carbide reinforced graphite material according to claim 1, characterized in that, In step 1, the vacuum level of the high vacuum environment is not less than 10. -3 Pa, and the holding time shall not be less than 12 hours.

3. The method for preparing silicon carbide reinforced graphite material according to claim 1, characterized in that, The porous graphite matrix has a porosity of 20-40% and a pore size distribution of 1-10 μm.

4. The method for preparing silicon carbide reinforced graphite material according to claim 1, characterized in that, In step 3, the inert atmosphere is nitrogen, argon, or helium. The inert atmosphere gas flow rate is 0.5~2L / min.

5. The method for preparing silicon carbide reinforced graphite material according to claim 1, characterized in that, In step 4, the material is cooled to room temperature at a cooling rate of 5~10℃ / min; Surface polishing is performed using diamond grinding wheels or silicon carbide sandpaper, with a polishing precision of Ra≤0.8μm.

6. A silicon carbide-reinforced graphite material, characterized in that, Prepared by the method according to any one of claims 1-5.

7. The application of silicon carbide reinforced graphite materials prepared by the method of any one of claims 1-5 in the fields of metallurgy, chemical industry, machinery, electronics and aerospace.

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