C / C-SiC composite material with surface low-residual silicon coating and preparation method of C / C-SiC composite material

Abstract

The invention belongs to the technical field of composite material coating preparation, and particularly relates to a C / C-SiC composite material with a surface low-residual silicon coating and a preparation method of the C / C-SiC composite material. The method comprises the following steps: brushing a coating on the surface of a C / C substrate, airing, then brushing an inhibition coating to obtain a composite material 1, assembling the composite material 1 with a fusion siliconizing tool to obtain an assembly, then putting the assembly into a high-temperature furnace, carrying out fusion siliconizing to obtain a composite material 2, and then carrying out accurate grinding and polishing to obtain the C / C-SiC composite material with the surface low residual silicon coating. Liquid silicon is permeated into a C / C substrate and a coating at high temperature, the C / C substrate is densified, the SiC coating is generated through reaction, and the content of SiC is larger than 70%; bN capable of inhibiting flowing of liquid silicon is left after resin cracking in the melting siliconizing process of the inhibiting coating, residual silicon on the surface of the SiC coating is little, the situation that the structure of the SiC coating is damaged by brittle failure during silicon removal can be effectively avoided, and the performance of the material is optimized.

Description

Technical Field

[0001] The invention belongs to the technical field of composite material coating preparation, and in particular relates to a C / C-SiC composite material with a low-residual silicon coating on the surface and a preparation method thereof. Background Art

[0002] C / C-SiC composite material is a three-phase composite material of carbon fiber, silicon carbide and silicon. C / C-SiC composite material has excellent properties such as low density, high structural strength, corrosion resistance and high temperature resistance. The surface coating of C / C-SiC composite material has the function of improving the oxidation resistance and wear resistance of the composite material. At present, C / C-SiC is often used in the fields of high-temperature structural materials, friction materials and functional materials. However, there are still some shortcomings in the production process of C / C-SiC composite material: since C / C-SiC composite material is obtained by molten siliconization reaction of C / C composite material, a large amount of residual silicon is easy to appear on the surface of the coating, resulting in high complexity of subsequent processing; and silicon is brittle and hard, and it is easy to damage the SiC coating when it is removed, affecting the excellent performance of C / C-SiC composite material. Therefore, finding a C / C-SiC composite material with a low residual silicon coating on the surface and its preparation method has become an urgent problem to be solved. Summary of the invention

[0003] The object of the present invention is to provide a C / C-SiC composite material with a low-surplus silicon coating on the surface and a preparation method thereof, aiming to solve the problem of a large amount of surplus silicon on the coating surface of the C / C-SiC composite material during production.

[0004] The technical solution of the present invention is:

[0005] A method for preparing a C / C-SiC composite material having a low residual silicon coating on the surface comprises the following steps:

[0006] (1) coating a layer with a thickness of 0.5 to 0.8 mm on one surface of a C / C substrate to obtain a C / C composite material 1;

[0007] (2) after the coating in the C / C composite material 1 in step (1) is dried, a layer of inhibitor coating with a thickness of 0.1 to 0.3 mm is applied on the surface of the coating to obtain a C / C composite material 2;

[0008] (3) the composite material 1 obtained after the inhibitory coating of the C / C composite material 2 in step (2) is dried;

[0009] (4) assembling the composite material 1 in step (3) with a melt-siliconizing tool to obtain an assembly;

[0010] (5) placing the assembly in a high-temperature furnace for melt siliconization, and in a nitrogen atmosphere maintained at 1 atm, heating the temperature from room temperature to 400°C at a heating rate of 1-2°C / min, and keeping the temperature for 0.5-2h; then heating the temperature to 800°C at a heating rate of 1-2°C / min, and keeping the temperature for 1h-2h; then heating the temperature to 1200°C at a heating rate of 1-2°C / min, and keeping the temperature for 2-3h; then evacuating the temperature, and heating the temperature to 1500°C at a heating rate of 1-2°C / min, and keeping the temperature for 0.5-1h; then cooling the temperature naturally to room temperature to obtain composite material 2;

[0011] (6) The composite material 2 is ground to remove the inhibition layer, and then fine-ground and polished to obtain a C / C-SiC composite material with a low residual silicon coating on the surface.

[0012] Furthermore, the C / C matrix described in step (1) is a rectangular plate woven from needle-punched non-woven carbon fiber, with a density range of 1.2 to 1.5 g / cm 3 .

[0013] Furthermore, in step (1), the coating is a uniform mixture of 30wt% to 50wt% SiC powder, 10wt% to 30wt% carbon black, 20wt% to 40wt% water-soluble resin, and 0.3wt% to 0.5wt% modifier, wherein the SiC powder particle size is 10 to 20μm, the carbon black particle size is 3 to 5μm, the water-soluble resin is a polyvinyl alcohol aqueous solution with a water content of 80 to 90wt%, and the modifier is a mixed modified solution of one or more of polyethanol, polyethyleneimine, tetramethylammonium hydroxide, polyacrylic acid, and polyacrylamide.

[0014] Furthermore, the inhibitory coating in step (2) is a uniform mixture of 50wt% to 70wt% anhydrous ethanol, 30wt% to 40wt% BN powder and 4wt% to 8wt% phenolic resin.

[0015] Furthermore, the molten siliconizing tooling described in step (4) includes a BN crucible, carbon wood and silicon.

[0016] Furthermore, the assembly described in step (4) is assembled by spreading some silicon in the BN crucible, placing some carbon wood vertically, and then the carbon wood supports the composite material 1; wherein the carbon wood has the same height and supports the composite material 1 on the opposite side of the coating of the inhibition coating.

[0017] Another object of the present invention is to provide a C / C-SiC composite material with a low residual silicon coating on the surface, comprising a C / SiC matrix and a SiC coating; wherein the C / SiC matrix is ​​obtained by molten siliconization of a C / C matrix; and the SiC coating is obtained by molten siliconization reaction of the coating.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] (1) The present invention adopts a melt siliconizing method to infiltrate liquid silicon into a C / C substrate and a coating at a high temperature to achieve densification of the C / C substrate and reaction to generate a SiC coating. The melt siliconizing method has the advantages of fast melting and infiltration speed, low production cost, and sufficient reaction; the C / SiC substrate obtained by densifying the C / C substrate has the advantages of light weight and dense structure; the SiC coating generated by the reaction has a SiC content of more than 70%.

[0020] (2) In the method of the present invention, the resin of the coating is cracked during the melt siliconization process of the technical solution, leaving BN that can inhibit the flow of liquid silicon. After the melt siliconization is completed, there is no large amount of residual silicon on the surface of the SiC coating, which is convenient for subsequent surface processing; the small amount of residual silicon can effectively avoid the brittle fracture that occurs when removing silicon and destroying the SiC coating structure.

[0021] (3) In the method of the present invention, the melt siliconizing tool adopts a flow diversion method. Specifically, the silicon in the BN crucible is melted into liquid silicon during the melt siliconizing, and the carbon wood block guides the liquid silicon into the C / C matrix through capillary force to complete the melt siliconizing. During the melt siliconizing process, the C / C matrix does not contact the liquid silicon surface, thereby avoiding the adhesion of residual silicon on the surface of the C / C-SiC composite material, which is convenient for subsequent processing.

[0022] (4) The C / C-SiC composite material with a low residual silicon coating on the surface finally prepared by the present invention has a dense structure, a neat surface, and is easy to grind after melt siliconization, which effectively improves the processing efficiency and optimizes the performance of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The drawings described herein are used to provide further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0024] Figure 1 It is a flow chart of the preparation method of the present invention;

[0025] Figure 2 Schematic diagram of the C / C matrix structure of the present invention;

[0026] Figure 3 It is a schematic diagram of the structure of the composite material 1 of the present invention;

[0027] Figure 4 Schematic diagram of the melt siliconizing tooling of the present invention;

[0028] Figure 5 Schematic diagram of the metallographic micrograph of the C / C-SiC composite material coating obtained in Example 1 of the present invention.

[0029] Figure 6 is a schematic diagram of the coating surface of the composite material 2 obtained in Example 1 of the present invention;

[0030] Figure 7 It is a schematic diagram of the coating surface of the composite material 2 obtained in Comparative Example 4 of the present invention.

[0031] In the figure, 1. coating; 2. inhibition coating; 3. BN crucible; 4. carbon wood; 5. silicon powder. DETAILED DESCRIPTION

[0032] The present invention is further illustrated below through the description of specific implementation methods, but this is not a limitation of the present invention. Those skilled in the art can make various modifications or improvements based on the basic idea of ​​the present invention, but as long as they do not deviate from the basic idea of ​​the present invention, they are all within the protection scope of the present invention.

[0033] Example 1 A method for preparing a C / C-SiC composite material having a low residual silicon coating on the surface, referring to Figure 1 As shown, the following steps are included:

[0034] (1) coating a coating 1 with a thickness of 0.5 mm on one surface of a C / C substrate to obtain a C / C composite material 1;

[0035] The C / C matrix is ​​a rectangular plate made of needle-punched carbon fiber with a density range of 1.2g / cm 3 (Refer to Figure 2 As shown); coating 1 is a uniform mixture of 40wt% SiC powder, 30wt% carbon black, 29.5wt% water-soluble resin (specifically a polyvinyl alcohol aqueous solution with a water content of 90wt%) and 0.5wt% polyethanol solution, wherein the SiC powder particle size is 15μm and the carbon black particle size is 3μm;

[0036] (2) after the coating 1 in the C / C composite material 1 in step (1) is dried, a layer of inhibition coating 2 with a thickness of 0.2 mm is applied on the surface of the coating to obtain a C / C composite material 2;

[0037] Wherein, the inhibitory coating 2 is a uniform mixture of 55wt% anhydrous ethanol, 40wt% BN powder, and 5wt% phenolic resin;

[0038] (3) The composite material 1 obtained after the inhibitory coating 2 of the C / C composite material 2 in step (2) is dried (refer to Figure 3 shown);

[0039] (4) In step (3), the composite material 1 is assembled with a melt-siliconized tool to obtain an assembly (refer to Figure 4As shown); wherein, the molten siliconizing tooling comprises a BN crucible 3, carbon wood 4 and silicon powder 5; the molten siliconizing tooling is assembled by spreading a number of silicon powders 5 in the BN crucible 3, and then vertically placing a number of carbon woods 4, the carbon woods 4 being used to support the composite material 1; wherein the carbon woods 4 have a uniform height and are supported on the opposite side of the composite material 1 where the inhibition coating is applied.

[0040] (5) The assembly was placed in a high-temperature furnace for melt siliconization. In a nitrogen atmosphere maintained at 1 atm, the temperature was raised from room temperature to 400°C at a rate of 2°C / min and kept at that temperature for 2 h; then the temperature was raised to 800°C at a rate of 2°C / min and kept at that temperature for 2 h; then the temperature was raised to 1200°C at a rate of 2°C / min and kept at that temperature for 2.5 h; then the vacuum was evacuated and the temperature was raised to 1500°C at a rate of 2°C / min and kept at that temperature for 0.5 h; then the temperature was naturally cooled to room temperature to obtain the composite material 2( Figure 6 is a schematic diagram of the coating surface of the composite material 2); from Figure 6 It can be seen that the coating surface is smooth and has no obvious excess silicon.

[0041] (6) The composite material 2 is ground to remove the inhibition layer, and then fine-ground and polished to obtain a C / C-SiC composite material with a low residual silicon coating on the surface.

[0042] in Figure 5 Figure 1 is a metallographic microscopic diagram of the C / C-SiC composite material coating obtained in this example. Figure 5 It can be seen that in the coating, the crack width is 0.01 mm; SiC and Si are evenly distributed; and the SiC content is greater than 70%.

[0043] Embodiment 2 A method for preparing a C / C-SiC composite material having a low residual silicon coating on the surface comprises the following steps:

[0044] (1) coating a coating 1 with a thickness of 0.6 mm on one surface of a C / C substrate to obtain a C / C composite material 1;

[0045] The C / C matrix is ​​a rectangular plate made of needle-punched carbon fiber with a density range of 1.3g / cm 3 ; Coating 1 is a uniform mixture of 50wt% SiC powder, 20wt% carbon black, 29.6wt% water-soluble resin (specifically, a polyvinyl alcohol aqueous solution with a water content of 85wt%) and 0.4wt% polyacrylamide, wherein the SiC powder particle size is 10μm and the carbon black particle size is 4μm;

[0046] (2) after the coating 1 in the C / C composite material 1 in step (1) is dried, a layer of inhibition coating 2 with a thickness of 0.1 mm is applied on the surface of the coating to obtain a C / C composite material 2;

[0047] Wherein, the inhibition coating 2 is a uniform mixture of 70wt% anhydrous ethanol, 25wt% BN powder, and 5wt% phenolic resin;

[0048] (3) the composite material 1 obtained after the inhibitory coating 2 of the C / C composite material 2 in step (2) is dried;

[0049] (4) In step (3), the composite material 1 is assembled with a melt siliconizing tool to obtain an assembly; wherein the melt siliconizing tool comprises a BN crucible 3, carbon wood 4 and silicon powder 5; the melt siliconizing tool is assembled by spreading a number of silicon powders 5 in the BN crucible 3, and then vertically placing a number of carbon woods 4, the carbon woods 4 being used to support the composite material 1; wherein the height of the carbon woods 4 is consistent, and they are supported on the opposite side of the composite material 1 where the inhibitory coating is applied.

[0050] (5) placing the assembly in a high-temperature furnace for melt siliconization, and in a nitrogen atmosphere maintained at 1 atm, heating the temperature from room temperature to 400°C at a rate of 1°C / min, and keeping the temperature for 1 hour; then heating the temperature to 800°C at a rate of 1°C / min, and keeping the temperature for 1 hour; then heating the temperature to 1200°C at a rate of 1°C / min, and keeping the temperature for 2 hours; then evacuating the temperature, heating the temperature to 1500°C at a rate of 2°C / min, and keeping the temperature for 0.75 hours; then cooling the temperature naturally to room temperature to obtain composite material 2;

[0051] (6) The composite material 2 is ground to remove the inhibition layer, and then fine-ground and polished to obtain a C / C-SiC composite material with a low residual silicon coating on the surface.

[0052] Embodiment 3 A method for preparing a C / C-SiC composite material having a low residual silicon coating on the surface comprises the following steps:

[0053] (1) coating a coating 1 with a thickness of 0.8 mm on one surface of a C / C substrate to obtain a C / C composite material 1;

[0054] The C / C matrix is ​​a rectangular plate made of needle-punched carbon fiber with a density range of 1.5g / cm 3 ; Coating 1 is a uniform mixture of 40wt% SiC powder, 10wt% carbon black, 29.7wt% water-soluble resin (specifically a polyvinyl alcohol aqueous solution with a water content of 90wt%) and 0.3wt% of a mixed solution of polyethanol and polyacrylic acid, wherein the SiC powder particle size is 10μm and the carbon black particle size is 4μm; the weight ratio of polyethanol and polyacrylic acid in the mixed solution is 1:1.

[0055] (2) after the coating 1 in the C / C composite material 1 in step (1) is dried, a layer of inhibition coating 2 with a thickness of 0.3 mm is applied on the surface of the coating to obtain a C / C composite material 2;

[0056] Wherein, the inhibition coating 2 is a uniform mixture of 65wt% anhydrous ethanol, 27wt% BN powder, and 8wt% phenolic resin;

[0057] (3) the composite material 1 obtained after the inhibitory coating 2 of the C / C composite material 2 in step (2) is dried;

[0058] (4) In step (3), the composite material 1 is assembled with a melt siliconizing tool to obtain an assembly; wherein the melt siliconizing tool comprises a BN crucible 3, carbon wood 4 and silicon powder 5; the melt siliconizing tool is assembled by spreading a number of silicon powders 5 in the BN crucible 3, and then vertically placing a number of carbon woods 4, the carbon woods 4 being used to support the composite material 1; wherein the height of the carbon woods 4 is consistent, and they are supported on the opposite side of the composite material 1 where the inhibitory coating is applied.

[0059] (5) placing the assembly in a high-temperature furnace for melt siliconization, and in a nitrogen atmosphere maintained at 1 atm, heating the temperature from room temperature to 400°C at a rate of 2°C / min, and keeping the temperature for 2 h; then heating the temperature to 800°C at a rate of 2°C / min, and keeping the temperature for 2 h; then heating the temperature to 1200°C at a rate of 2°C / min, and keeping the temperature for 3 h; then evacuating the vacuum, heating the temperature to 1500°C at a rate of 2°C / min, and keeping the temperature for 1 h; then cooling the temperature naturally to room temperature to obtain composite material 2;

[0060] (6) The composite material 2 is ground to remove the inhibition layer, and then fine-ground and polished to obtain a C / C-SiC composite material with a low residual silicon coating on the surface.

[0061] The relevant properties of the C / C-SiC composite materials obtained in Examples 1 to 3 were tested, wherein the excess silicon was equal to the mass of the composite material 1 minus the mass of the C / C-SiC composite material. The apparent crack width was observed using a metallographic microscope, and 10 cracks were measured with a ruler to obtain an average value. The density was measured using the Archimedean drainage method. The specific results are shown in Table 1.

[0062] Table 1 Comparison of properties of C / C-SiC composite materials obtained from Example 1 to Example 3

[0063]

[0064] By comparing the data in Table 1, it can be concluded that Example 1 is the best example of the present invention. Further, with reference to the best example, the following comparative examples are added.

[0065] Comparative Example 1 A method for preparing a C / C-SiC composite material having a low-residual silicon coating on the surface,

[0066] Compared with Example 1, the difference of Comparative Example 1 is that in step (1), the coating 1 is a uniform mixture of 58wt% SiC powder, 30wt% carbon black, 29.5wt% water-soluble resin (specifically, a polyvinyl alcohol aqueous solution with a water content of 90wt%), and 0.5wt% polyethanol solution, wherein the SiC powder particle size is 15μm and the carbon black particle size is 3μm. Other operations and process parameters are the same as those of Example 1.

[0067] Comparative Example 2 A method for preparing a C / C-SiC composite material having a low residual silicon coating on the surface,

[0068] Compared with Example 1, the difference of Comparative Example 2 is that in step (2), the inhibitory coating 2 is a uniform mixture of 55wt% anhydrous ethanol, 40wt% BN powder, and 3wt% phenolic resin; other operations and process parameters are the same as those of Example 1.

[0069] Comparative Example 3 A method for preparing a C / C-SiC composite material having a low residual silicon coating on the surface,

[0070] Compared with Example 1, the difference of Comparative Example 3 is that in step (1), coating 1 is a uniform mixture of 40wt% SiC powder, 30wt% carbon black, 29.5wt% water-soluble resin (specifically polyacrylic acid with a water content of 90wt%) and 0.5wt% polyethanol solution, wherein the particle size of SiC powder is 15μm and the particle size of carbon black is 3μm;

[0071] In step (2), the inhibitory coating 2 is a uniform mixture of 55 wt% n-butanol, 40 wt% BN powder, and 5 wt% epoxy resin;

[0072] Other operation and process parameters are the same as those in Example 1.

[0073] Comparative Example 4 A method for preparing a C / C-SiC composite material having a low residual silicon coating on the surface comprises the following steps:

[0074] (1) coating a coating 1 with a thickness of 0.5 mm on one surface of a C / C substrate to obtain a C / C composite material 1;

[0075] The C / C matrix is ​​a rectangular plate made of needle-punched carbon fiber with a density range of 1.2g / cm 3 ; Coating 1 is a uniform mixture of 40wt% SiC powder, 30wt% carbon black, 29.5wt% water-soluble resin (specifically a polyvinyl alcohol aqueous solution with a water content of 90wt%) and 0.5wt% polyethanol solution, wherein the SiC powder particle size is 15μm and the carbon black particle size is 3μm;

[0076] (2) The C / C composite material 1 in step (1) is assembled with a melt siliconizing tool to obtain an assembly; wherein the melt siliconizing tool comprises a BN crucible 3, carbon wood 4 and silicon powder 5; the melt siliconizing tool is assembled by spreading a number of silicon powders 5 in the BN crucible 3, and then vertically placing a number of carbon woods 4, the carbon woods 4 being used to support the composite material 1; wherein the height of the carbon woods 4 is consistent, and they are supported on the opposite side of the composite material 1 where the inhibitory coating is applied.

[0077] (5) placing the assembly in a high-temperature furnace for melt siliconization, and in a nitrogen atmosphere maintained at 1 atmosphere, heating the temperature from room temperature to 400°C at a rate of 2°C / min, and keeping the temperature for 2 hours; then heating the temperature to 800°C at a rate of 2°C / min, and keeping the temperature for 2 hours; then heating the temperature to 1200°C at a rate of 2°C / min, and keeping the temperature for 2.5 hours; then evacuating the temperature, heating the temperature to 1500°C at a rate of 2°C / min, and keeping the temperature for 0.5 hours; then cooling the temperature naturally to room temperature to obtain composite material 2; Figure 7 Schematic diagram of the coating surface of the composite material 2. It can be seen from the figure that the coating surface is uneven and has very obvious excess silicon.

[0078] (6) The composite material 2 is finely ground and polished to obtain a C / C-SiC composite material.

[0079] The same method was used to detect the relevant properties of the C / C-SiC composite materials obtained in Comparative Examples 1 to 4. The specific data are shown in Table 2.

[0080] Table 2 Comparison of relevant properties of C / C-SiC composite materials obtained in Example 1 and Comparative Examples 1-4

[0081]

[0082]

[0083] It can be concluded from the data in Table 2 that the product obtained by the method of the present invention is significantly better than the comparative example in terms of final performance. The present invention adopts a melt siliconizing method to infiltrate liquid silicon into the C / C matrix and coating at a high temperature to achieve densification of the C / C matrix and reaction to generate a SiC coating. The SiC coating generated by the reaction has a SiC content of >70%. In addition, the coating is inhibited from resin cracking during the melt siliconizing process of the technical solution to leave BN that can inhibit the flow of liquid silicon. After the melt siliconizing is completed, there is no large amount of residual silicon on the surface of the SiC coating, which is convenient for subsequent surface processing. The small amount of residual silicon can effectively avoid the brittle fracture that occurs when silicon is removed and destroys the SiC coating structure. Among them, the melt siliconizing tooling adopts a diversion method. The silicon in the BN crucible in the melt siliconizing melts into liquid silicon, and the carbon wood block guides the liquid silicon into the C / C matrix through capillary force to complete the melt siliconizing. During the melt siliconizing process, the C / C matrix does not contact the liquid silicon surface, which avoids the adhesion of residual silicon on the surface of the C / C-SiC composite material, which is convenient for subsequent processing. The C / C-SiC composite material prepared by the method of the invention has a compact structure, a neat surface, and is convenient for grinding and processing after melt siliconization, thereby optimizing the use performance of the material.

[0084] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A method for preparing a C / C-SiC composite material having a low residual silicon coating on the surface, characterized in that: The steps include: (1) coating a layer with a thickness of 0.5 to 0.8 mm on one surface of a C / C substrate to obtain a C / C composite material 1; (2) after the coating in the C / C composite material 1 in step (1) is dried, a layer of inhibitor coating with a thickness of 0.1 to 0.3 mm is applied on the surface of the coating to obtain a C / C composite material 2; (3) the composite material 1 obtained after the inhibitory coating of the C / C composite material 2 in step (2) is dried; (4) assembling the composite material 1 in step (3) with a melt-siliconizing tool to obtain an assembly; (5) placing the assembly in a high-temperature furnace for melt siliconization, and in a nitrogen atmosphere maintained at 1 atmosphere, heating the temperature from room temperature to 400°C at a rate of 1 to 2°C / min, and keeping the temperature for 0.5 to 2 hours; then heating the temperature to 800°C at a rate of 1 to 2°C / min, and keeping the temperature for 1 hour to 2 hours; then heating the temperature to 1200°C at a rate of 1 to 2°C / min, and keeping the temperature for 2 to 3 hours; evacuating the vacuum, heating the temperature to 1500°C at a rate of 1 to 2°C / min, and keeping the temperature constant for 0.5 to 1 hour; then cooling the temperature naturally to room temperature to obtain composite material 2; (6) The composite material 2 is ground to remove the inhibition layer, and then fine-ground and polished to obtain a C / C-SiC composite material with a low residual silicon coating on the surface.

2. The method for preparing a C / C-SiC composite material having a low-residual silicon coating on the surface according to claim 1, characterized in that: The C / C matrix described in step (1) is a rectangular plate made by needle-punching non-woven carbon fiber, with a density range of 1.2 to 1.5 g / cm 3 .

3. The method for preparing a C / C-SiC composite material having a low-residual silicon coating on the surface according to claim 1, characterized in that: The coating in step (1) is a uniform mixture of 30wt% to 50wt% SiC powder, 10wt% to 30wt% carbon black, 20wt% to 40wt% water-soluble resin, and 0.3wt% to 0.5wt% modifier, wherein the SiC powder particle size is 10 to 20μm, the carbon black particle size is 3 to 5μm, the water-soluble resin is a polyvinyl alcohol aqueous solution with a water content of 80 to 90wt%, and the modifier is a mixed modified solution of one or more of polyethanol, polyethyleneimine, tetramethylammonium hydroxide, polyacrylic acid, and polyacrylamide.

4. The method for preparing a C / C-SiC composite material having a low-residual silicon coating on the surface according to claim 1, characterized in that: The inhibitory coating in step (2) is a uniform mixture of 50wt% to 70wt% anhydrous ethanol, 30wt% to 40wt% BN powder and 4wt% to 8wt% phenolic resin.

5. The method for preparing a C / C-SiC composite material having a surface low residual silicon coating according to claim 1, characterized in that: The molten silicon infiltration tooling described in step (4) includes a BN crucible, carbon wood and silicon.

6. The method for preparing a C / C-SiC composite material having a low residual silicon coating on the surface according to claim 1, characterized in that: The assembly described in step (4) is assembled by spreading some silicon in a BN crucible, placing some carbon wood vertically, and then using the carbon wood to support the composite material 1; wherein the carbon wood has the same height and supports the composite material 1 on the opposite side of the coating that inhibits the coating.

7. A C / C-SiC composite material prepared by the method according to any one of claims 1 to 6, characterized in that: The invention comprises a C / SiC substrate and a SiC coating, wherein the C / SiC substrate is obtained by molten siliconization of the C / C substrate; and the SiC coating is obtained by molten siliconization reaction of the coating.

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