A preparation method and device for composite boron carbide ceramics

Abstract

The present invention relates to the technical field of boron carbide ceramics, and specifically to a preparation method and device for composite boron carbide ceramics, wherein the preparation method for composite boron carbide ceramics comprises the following steps: using thermosetting organic material monomers and boron carbide powders for ball milling to obtain a gel mixture; degassing and pouring the obtained gel mixture, curing, heating and carbonizing, and then molding to obtain a carbon-containing composite material; vacuum siliconizing and reaction sintering the carbon-containing composite material, and then turning off the outer silicon layer to obtain a composite boron carbide ceramic; wherein, after the gel is poured, at least two pieces of carbon fiber reinforcement materials are immersed in the gel. Boron carbide is uniform in the entire system, and carbon fiber reinforcement materials are provided inside the gel. After carbonization and molding, the boron carbide material can achieve both an increase in density and a uniform dispersion of the carbon source, which is beneficial to the subsequent reaction sintering and an increase in fracture toughness.

Description

Technical Field

[0001] The invention relates to the technical field of boron carbide ceramics, and in particular to a preparation method and device of composite boron carbide ceramics. Background Art

[0002] Boron carbide is a compound with excellent performance and stable chemical properties. It also has a strong ability to absorb seeds. Based on these excellent properties, boron carbide has been widely used in many fields such as wear-resistant and corrosion-resistant devices, bulletproof armor, nuclear energy, etc. The atomic radius of B and C is very close, and the difference in electronegativity between the two is very small, forming a strong covalent bond. Boron carbide is easy to agglomerate during sintering, and the fracture toughness of the finished product is very low. These two fatal weaknesses have greatly limited the application of boron carbide ceramics.

[0003] The invention patent with application number 201610156941.3 discloses a gel injection molding preparation method for reaction-sintered boron carbide ceramic composite materials: 1): Mix resorcinol, formaldehyde, sodium carbonate and deionized water, add B4C powder to form a B4C mixed slurry; 2): The mixed slurry is vacuum degassed and sealed by injection molding; Sol gelation is carried out in a water bath and aged for 4 to 50 hours; After normal pressure drying, high-temperature carbonization is performed to obtain a B4C / C blank; 3): Silicon is placed on the B4C / C blank, and high-temperature infiltration is performed to obtain a sintered body, and excess silicon is removed by cooling to obtain a reaction-sintered boron carbide ceramic composite material. The strength of the obtained B4C / C blank is 10 to 50 MPa, which is conducive to mechanical processing and can be used to prepare complex-shaped products; the Vickers hardness of the reaction-sintered boron carbide ceramic composite material is 17 to 26 GPa, the flexural strength is 255 to 484 MPa, and the fracture toughness is 3 to 5 MPa·m 1 / 2 Although the uniformity is improved to a certain extent, the fracture toughness is not significantly improved.

[0004] Therefore, there is an urgent need for a preparation method of composite boron carbide ceramics to solve the above technical problems, make up for the problem of low fracture toughness of boron carbide ceramics, and expand the application range of boron carbide ceramics. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a method and device for preparing composite boron carbide ceramics, so as to reduce the "bridge arch effect" during the molding process, reduce the gap between powders, make the boron carbide ceramics denser, and thus improve its fracture toughness.

[0006] The technical solution adopted by this application to solve this technical problem is:

[0007] A method for preparing a composite boron carbide ceramic comprises the following steps:

[0008] Step S1: ball milling a thermosetting organic material monomer and boron carbide powder to obtain a gel mixture;

[0009] Step S2: degassing, pouring and curing the gel mixture obtained in step S1, heating and carbonizing it, and then molding it to obtain a carbon-containing composite material;

[0010] Step S3: vacuum siliconizing and reaction sintering the carbon-containing composite material obtained in step S3, and then turning off the outer silicon layer to obtain a composite boron carbide ceramic;

[0011] Wherein, in said step S2, after the gel is poured, at least two pieces of carbon fiber reinforced materials are immersed in the gel, and after carbonization, there is a gap between at least two pieces of carbon fiber reinforced materials and between the carbon fiber reinforced materials and the surface of the carbon-containing composite material.

[0012] In order to enhance the fracture toughness of boron carbide ceramics, carbon fiber materials are used to strengthen boron carbide ceramics. After being strengthened with carbon fiber materials, the fracture performance of boron carbide ceramics can be greatly enhanced, and it has better mechanical properties.

[0013] The present invention uses gel and boron carbide powder for mixed ball milling, so that the boron carbide ceramic powder is dispersed more evenly, and the agglomeration problem is reduced. After the gel is solidified, the boron carbide ceramic is quickly fixed in the gel, and the whole system is in a uniform state. After carbonization, most of the materials in the gel are gasified and volatilized, and the carbon atoms are retained to form porous carbon. The porous carbon is formed by carbonization of organic gel materials, and they are coated on the surface of boron carbide particles and carbon fibers. During the sintering process, they react and sinter with boron carbide and silicon, and limit the growth of boron carbide particles, and also form a bracket to support the gaps between boron carbide particles. However, their strength is not high. After molding, the bracket formed by the porous carbon can be broken, so that the boron carbide material can achieve an increase in density and ensure the uniform dispersion of the carbon source, which is beneficial to the later reaction sintering. Molding can also provide initial prestress for the carbon fibers, and improve the overall mechanical properties of the material.

[0014] There is a distance between the carbon fiber reinforced material and the surface of the gel. On the one hand, it can ensure that the carbon fiber is immersed in the gel to increase the bonding strength. On the other hand, it can avoid damaging the carbon fiber during the subsequent turning process after molding, thereby affecting the overall mechanical properties of the material.

[0015] Furthermore, in step S2, the molding pressure is 100-150 MPa, and the holding time is 1 min.

[0016] The molding pressure can cause the carbon brackets between the boron carbide particles to break, the distance between the boron carbide particles to decrease, the composite material as a whole to be more dense, and the fracture toughness to be higher after molding. The thickness of the material after molding can be controlled by adjusting the pouring thickness.

[0017] Furthermore, the carbon fiber reinforced material is a carbon fiber mesh or a carbon fiber felt, and the carbon fiber felt is a loose felt formed by air-laying carbon fibers without needle punching, and has a density of 9-11 kg / m3.

[0018] The pores between the fibers of the unneedled carbon fiber felt are relatively large, allowing the gel material to carry the boron carbide material into the spaces between the carbon fibers to form an infiltration, thereby allowing the carbon fibers to occupy a larger volume within the composite boron carbide ceramic material and forming a three-dimensional network within the composite boron carbide ceramic, thereby producing a stronger composite reinforcement effect.

[0019] Furthermore, in step S2, the carbonization heating rate is 5-10°C / min, the carbonization temperature is 850-950°C, and the insulation time is 1-2h.

[0020] The carbonization temperature here is preferably 900°C. Too high a temperature can easily lead to damage of the carbon fibers and affect the mechanical properties. Too low a temperature can cause the carbon in the gel mixture to be completely carbonized. Even if the carbonization time is extended, the carbonization cannot be completed well. Instead, a large amount of gas is generated during the sintering process, which has an adverse effect on the reaction sintering of boron carbide.

[0021] Furthermore, in step S1, the thermosetting organic material is a phenolic resin material, and the mass ratio of the phenolic resin to boron carbide is 3-5:5-7.

[0022] Among various thermosetting organic materials, phenolic resin has good wetting properties on carbon fibers and can have a good wetting effect with carbon fibers. The porous carbon formed after carbonization can also have good bonding strength with carbon fibers to strengthen the connection.

[0023] Furthermore, the average particle size of the boron carbide powder is 3.5-5 μm.

[0024] A preparation device for composite boron carbide ceramics, comprising a ball mill, a grouting machine, a mold, a molding machine and a vacuum sintering furnace, wherein the mold is composed of a "U"-shaped frame and two side plates, the two side plates are hinged to the "U"-shaped frame, the two side plates are buckled on both sides of the "U"-shaped frame to form a trough body with one side open, and the surfaces of the two side plates facing each other are both provided with a limiting mechanism connected to the "U"-shaped frame;

[0025] Each side plate is evenly distributed with connection holes, and positioning nails are connected in the connection holes. The positioning nails are used to connect the carbon fiber reinforced material.

[0026] Furthermore, the positioning pin is a columnar material made of hard plastic such as phenolic resin, and two bosses are provided on the positioning pin, which are respectively used to limit the insertion depth of the positioning pin in the connecting hole and the distance between the carbon fiber reinforced material and the side plate.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. The present invention uses gel and boron carbide powder for mixed ball milling. After the gel is solidified, the boron carbide ceramic is quickly fixed in the gel, and the entire system is in a uniform state. After carbonization, the gel forms porous carbon, which is coated on the surface of the boron carbide particles and carbon fibers, strengthens the toughening effect of the carbon fibers, and forms a bracket to support the gaps between the boron carbide particles. After molding, the bracket formed by the porous carbon can be broken, so that the boron carbide material can not only achieve an increased density, but also ensure the uniform dispersion of the carbon source, which is beneficial to the subsequent reaction sintering.

[0029] 2. The carbon fiber reinforced material of the present invention has a distance from the gel surface, which can not only strengthen the boron carbide ceramic material, but also avoid damage to the carbon fiber reinforced material due to turning during the processing after molding, thereby causing damage to the mechanical properties of the composite material. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a cross-sectional photo of the composite boron carbide ceramic prepared by the present invention.

[0031] Figure 2 It is a structural schematic diagram of the mold of the present invention (in use state);

[0032] Figure 3 yes Figure 2 AA section view;

[0033] Figure 4 It is a structural schematic diagram of the mold of the present invention (open state);

[0034] Figure 5 It is a structural schematic diagram of the positioning pin of the present invention.

[0035] The numbers in the attached drawings are: 1, "U"-shaped frame; 2, side panel; 3, hinge; 4, step; 5, sealing strip; 6, latch; 7, positioning ring; 8, connecting hole; 9, positioning pin; 10, boss. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments.

[0037] Embodiment 1:

[0038] A method for preparing a composite boron carbide ceramic comprises the following steps:

[0039] The monomers of phenolic resin (phenol and formaldehyde), ethanol and boron carbide powder are mixed in a mass ratio of 3:1:7, and ball milled for more than 24 hours to form a uniform dispersion. Silicon carbide balls are used for grinding, and the material-to-ball ratio is 1.5:1. During the ball milling process, the material temperature is strictly controlled not to exceed 30° C. A curing agent is added to the uniform dispersion, and stirred evenly to obtain a gel mixture;

[0040] The gel mixture is poured into a mold coated with a release agent, wherein two layers of carbon fiber felt are provided in the mold with a spacing from the inner wall of the mold, wherein the carbon fiber felt is a mesh felt material which is not needle-punched after air-forming, and has large pores between adjacent fibers. After vacuum degassing, the material is added to an environment of 75-85°C for curing, and demolded after curing. The cured material is dried at 110°C-120°C for 1-2h, and the dried material is transferred to a carbonization furnace for carbonization, and the temperature is increased to 850°C at a heating rate of 5-10°C / min, and the temperature is kept for 2h. After cooling with the furnace, the carbonized material is taken and put into a molding press for molding. The molding pressure is 150MPa and the pressure is maintained for 1min to reduce the thickness of the material, thereby obtaining a carbon-containing composite material;

[0041] The obtained carbon-containing composite material is subjected to vacuum siliconization reaction sintering at a sintering temperature of 1600-1650° C., and then the outer layer of silicon is turned off to obtain composite boron carbide ceramics.

[0042] Embodiment 2:

[0043] A method for preparing a composite boron carbide ceramic comprises the following steps:

[0044] Phenolic resin monomers (phenol and formaldehyde), ethanol and boron carbide powder are mixed in a mass ratio of 4:1:6, and ball milled for more than 24 hours to form a uniform dispersion. Silicon carbide balls are used for grinding, and the material-to-ball ratio is 1.5:1. During the ball milling process, the material temperature is strictly controlled not to exceed 30° C. A curing agent is added to the uniform dispersion, and stirred evenly to obtain a gel mixture;

[0045] The gel mixture is poured into a mold coated with a release agent, wherein two layers of carbon fiber felt are provided in the mold and are spaced apart from the inner wall of the mold. After vacuum degassing, the mixture is added to an environment of 75-85°C for curing, and demolded after curing. The cured material is dried at 110-120°C for 1-2 hours, and the dried material is transferred to a carbonization furnace for carbonization, and the temperature is increased to 850°C at a heating rate of 5-10°C / min, and the temperature is kept for 2 hours. After cooling with the furnace, the carbonized material is taken and placed in a molding press for molding. The molding pressure is 150MPa and the pressure is maintained for 1 minute to reduce the thickness of the material, thereby obtaining a carbon-containing composite material.

[0046] The obtained carbon-containing composite material is subjected to vacuum siliconization reaction sintering at a sintering temperature of 1600-1650° C., and then the outer layer of silicon is turned off to obtain composite boron carbide ceramics.

[0047] Embodiment three:

[0048] A method for preparing a composite boron carbide ceramic comprises the following steps:

[0049] The monomers of phenolic resin (phenol and formaldehyde), ethanol and boron carbide powder are mixed in a mass ratio of 5:1.5:5, and ball milled for more than 24 hours to form a uniform dispersion. Silicon carbide balls are used for grinding, and the material-to-ball ratio is 1.5:1. During the ball milling process, the material temperature is strictly controlled not to exceed 30° C. A curing agent is added to the uniform dispersion, and stirred evenly to obtain a gel mixture;

[0050] The gel mixture is poured into a mold coated with a release agent, and two layers of carbon fiber felt are arranged in the mold with a distance from the inner wall of the mold. After vacuum degassing, it is added to an environment of 75-85°C for curing, and demolded after curing. The cured material is dried at 110°C-120°C for 1-2 hours, and the dried material is transferred to a carbonization furnace for carbonization, and the temperature is increased to 850°C at a heating rate of 5-10°C / min, and the temperature is kept for 1.5 hours. After cooling with the furnace, the carbonized material is taken and put into a molding machine for molding. The molding pressure is 150MPa and the pressure is maintained for 1 minute to reduce the thickness of the material to obtain a carbon-containing composite material;

[0051] The obtained carbon-containing composite material is subjected to vacuum siliconization reaction sintering at a sintering temperature of 1600-1650° C., and then the outer layer of silicon is turned off to obtain composite boron carbide ceramics.

[0052] Embodiment 4:

[0053] A method for preparing a composite boron carbide ceramic comprises the following steps:

[0054] The monomers of phenolic resin (phenol and formaldehyde), ethanol and boron carbide powder are mixed in a mass ratio of 5:1.5:5, and ball milled for more than 24 hours to form a uniform dispersion. Silicon carbide balls are used for grinding, and the material-to-ball ratio is 1.5:1. During the ball milling process, the material temperature is strictly controlled not to exceed 30° C. A curing agent is added to the uniform dispersion, and stirred evenly to obtain a gel mixture;

[0055] The gel mixture is poured into a mold coated with a release agent, wherein two layers of carbon fiber felt are provided in the mold and are spaced apart from the inner wall of the mold. After vacuum degassing, the mixture is added to an environment of 75-85°C for curing, and demolded after curing. The cured material is dried at 110-120°C for 1-2 hours, and the dried material is transferred to a carbonization furnace for carbonization, and the temperature is increased to 950°C at a heating rate of 5-10°C / min, and the temperature is kept for 2 hours. After cooling with the furnace, the carbonized material is taken and placed in a molding press for molding. The molding pressure is 150MPa and the pressure is maintained for 1 minute to reduce the thickness of the material, thereby obtaining a carbon-containing composite material.

[0056] The obtained carbon-containing composite material is subjected to vacuum siliconization reaction sintering at a sintering temperature of 1600-1650° C., and then the outer layer of silicon is turned off to obtain composite boron carbide ceramics.

[0057] Embodiment five:

[0058] A method for preparing a composite boron carbide ceramic comprises the following steps:

[0059] The monomers of phenolic resin (phenol and formaldehyde), ethanol and boron carbide powder are mixed in a mass ratio of 5:1.5:5, and ball milled for more than 24 hours to form a uniform dispersion. Silicon carbide balls are used for grinding, and the material-to-ball ratio is 1.5:1. During the ball milling process, the material temperature is strictly controlled not to exceed 30° C. A curing agent is added to the uniform dispersion, and stirred evenly to obtain a gel mixture;

[0060] The gel mixture is poured into a mold coated with a release agent, and two layers of carbon fiber felt are arranged in the mold with a distance from the inner wall of the mold. After vacuum degassing, it is added to an environment of 75-85°C for curing, and demolded after curing. The cured material is dried at 110°C-120°C for 1-2 hours, and the dried material is transferred to a carbonization furnace for carbonization, and the temperature is increased to 1000°C at a heating rate of 5-10°C / min, and the temperature is kept for 1.5 hours. After cooling with the furnace, the carbonized material is taken and put into a molding machine for molding. The molding pressure is 150MPa and the pressure is maintained for 1 minute to reduce the thickness of the material to obtain a carbon-containing composite material;

[0061] The obtained carbon-containing composite material is subjected to vacuum siliconization reaction sintering at a sintering temperature of 1600-1650° C., and then the outer layer of silicon is turned off to obtain composite boron carbide ceramics.

[0062] Embodiment six:

[0063] A method for preparing a composite boron carbide ceramic comprises the following steps:

[0064] The monomers of phenolic resin (phenol and formaldehyde), ethanol and boron carbide powder are mixed in a mass ratio of 5:1.5:5, and ball milled for more than 24 hours to form a uniform dispersion. Silicon carbide balls are used for grinding, and the material-to-ball ratio is 1.5:1. During the ball milling process, the material temperature is strictly controlled not to exceed 30° C. A curing agent is added to the uniform dispersion, and stirred evenly to obtain a gel mixture;

[0065] The gel mixture is poured into a mold coated with a release agent, wherein the mold is provided with two layers of carbon fiber felt spaced from the inner wall of the mold, and the carbon fiber felt is pretreated to remove the sizing agent, i.e., it is soaked in acetone, and the soaked carbon fiber felt is rinsed with alcohol and then dried; after vacuum degassing, it is added to an environment of 75-85°C for curing, demoulding after curing, and the cured material is dried at 110°C-120°C for 1-2h, and the dried material is transferred to a carbonization furnace for carbonization, and the temperature is increased to 900°C at a heating rate of 5-10°C / min, and the temperature is kept for 1.5h, and after cooling with the furnace, the carbonized material is taken and put into a molding machine for molding, and the molding pressure is 150MPa and the pressure is maintained for 1min to reduce the thickness, so as to obtain a carbon-containing composite material;

[0066] The obtained carbon-containing composite material is subjected to vacuum siliconization reaction sintering at a sintering temperature of 1600-1650° C., and then the outer layer of silicon is turned off to obtain composite boron carbide ceramics.

[0067] Comparative Example:

[0068] A method for preparing a composite boron carbide ceramic comprises the following steps:

[0069] The monomers of phenolic resin (phenol and formaldehyde), ethanol and boron carbide powder are mixed in a mass ratio of 5:1.5:5, and ball milled for more than 24 hours to form a uniform dispersion. Silicon carbide balls are used for grinding, and the material-to-ball ratio is 1.5:1. During the ball milling process, the material temperature is strictly controlled not to exceed 30° C. A curing agent is added to the uniform dispersion, and stirred evenly to obtain a gel mixture;

[0070] The gel mixture is poured into a mold coated with a release agent, and after vacuum degassing, it is added to a 75-85°C environment for curing, and demolded after curing. The cured material is dried at 110°C-120°C for 1-2 hours, and the dried material is transferred to a carbonization furnace for carbonization, and the temperature is increased to 900°C at a heating rate of 5-10°C / min, and the temperature is kept for 2 hours. After cooling with the furnace, the carbonized material is taken and put into a molding machine for molding. The molding pressure is 150MPa and the pressure is maintained for 1 minute to reduce the thickness of the material to obtain a carbon-containing composite material;

[0071] The obtained carbon-containing composite material is subjected to vacuum siliconization reaction sintering at a sintering temperature of 1600-1650° C., and then the outer layer of silicon is turned off to obtain composite boron carbide ceramics.

[0072] Figure 1 The cross-sectional photograph of the composite boron carbide ceramic prepared by the present invention is given. The product obtained in the above embodiment is tested for Vickers hardness, bending strength and fracture toughness. The results are as follows:

[0073] Example Vickers hardness(GPa) Flexural strength(MPa) <![CDATA[Fracture toughness (MPa·m 1 / 2 )]]> Embodiment 1 16 483 16.23 Embodiment 2 17 496 16.52 Embodiment 3 18 522 16.84 Embodiment 4 18 596 18.20 Embodiment 5 18 534 13.69 Embodiment 6 18 602 18.02 Comparative Example 19 415 4.89

[0074] Among them: Vickers hardness test method adopts GB / T16534 engineering ceramics Vickers hardness test method

[0075] The bending strength test method adopts GB / T4741-1999 ceramic material bending test method

[0076] The fracture toughness test method adopts BG / T23806-2009 fine ceramic fracture toughness test method

[0077] It can be seen from the above tests that the preparation method of the composite boron carbide ceramic has no obvious effect on the hardness of the composite boron carbide ceramic, but has a significant improvement in the bending strength and fracture toughness.

[0078] The apparatus used in the preparation method of the composite boron carbide ceramic includes a ball mill, a slip casting machine, a mold, a molding machine and a vacuum sintering furnace, wherein the mold is homemade, such as Figure 2 , Figure 3 and Figure 4 As shown, the mold is composed of a "U"-shaped frame 1 and two side panels 2, the two side panels 2 are connected to the "U"-shaped frame 1 via hinges 3, and the two side panels 2 are buckled on both sides of the "U"-shaped frame 1 to form a trough body with one side open. In order to prevent leakage, the "U"-shaped frame 1 is provided with a step 4 corresponding to the two frame frames, and the surface of the step 4 is provided with a sealing groove, and a sealing strip 5 is provided in the sealing groove. When the two side panels 2 are buckled on both sides of the "U"-shaped frame 1, the opposite surfaces of the two side panels 2 are respectively abutted against the sealing strip 5, and the opposite surfaces of the two side panels 2 are provided with latches 6, and the latches 6 are inserted into the positioning rings 7 on both sides of the "U"-shaped frame 1 to limit the two side panels 2;

[0079] Each side plate 2 is evenly provided with connection holes 8, and positioning nails 9 are connected in the connection holes 8. The positioning nails 9 are used to connect the carbon fiber felt. Figure 5 As shown, the positioning pin 9 is a columnar material made of hard plastic such as phenolic resin, and two bosses 10 are provided on the positioning pin 9, which are used to limit the insertion depth of the positioning pin 9 in the connecting hole 8 and the distance between the carbon fiber felt and the side plate 2 respectively.

[0080] The positioning pins 9 made of hard plastics such as phenolic resin can be integrated with the gel mixture after the gel mixture is solidified, and can be carbonized together during carbonization to eventually form a part of the composite boron carbide ceramic.

[0081] In the preparation method of the composite boron carbide ceramic of the present invention, the phenolic resin can also be replaced by an organic material in the form of heat curing or controlled reaction curing, as long as it can form residual carbon material during the carbonization process. The carbon fiber felt can also be replaced by asbestos mesh or basalt mesh. Without paying any creative labor, the present invention can be expanded to a variety of embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention and are not used to limit the present invention.

Claims

1. A method for preparing a composite boron carbide ceramic, characterized in that: The following steps are involved: Step S1: ball milling a thermosetting organic material monomer and boron carbide powder to obtain a gel mixture; Step S2: degassing, pouring and curing the gel mixture obtained in step S1, heating and carbonizing it, and then molding it to obtain a carbon-containing composite material; Step S3: vacuum siliconizing and reaction sintering the carbon-containing composite material obtained in step S3, and then turning off the outer silicon layer to obtain a composite boron carbide ceramic; Wherein, in said step S2, after the gel is poured, at least two pieces of carbon fiber reinforced materials are immersed in the gel, and after carbonization, there is a gap between at least two pieces of carbon fiber reinforced materials and between the carbon fiber reinforced materials and the surface of the carbon-containing composite material.

2. The method for preparing the composite boron carbide ceramic according to claim 1, characterized in that: The carbon fiber reinforced material is a carbon fiber mesh or a carbon fiber felt. The carbon fiber felt is a loose felt formed by air-forming carbon fibers without needle punching, and has a density of 9-11 kg / m3.

3. The method for preparing the composite boron carbide ceramic according to claim 1, characterized in that: In step S2, the molding pressure is 100-150 MPa, and the holding time is 1 min.

4. The method for preparing the composite boron carbide ceramic according to claim 1, characterized in that: In step S2, the carbonization heating rate is 5-10°C / min, the carbonization temperature is 850-950°C, and the insulation time is 1-2h.

5. The method for preparing the composite boron carbide ceramic according to claim 1, characterized in that: In the step S1, the thermosetting organic material is a phenolic resin material, and the mass ratio of the phenolic resin to boron carbide is 3-5:5-7.

6. The method for preparing a composite boron carbide ceramic according to claim 1, characterized in that: The average particle size of the boron carbide powder is 3.5-10 μm.

7. A preparation device for composite boron carbide ceramics, used to implement the preparation method for composite boron carbide ceramics according to any one of claims 1 to 6, characterized in that: The invention comprises a ball mill, a grouting machine, a mold, a molding machine and a vacuum sintering furnace, wherein the mold is composed of a "U"-shaped frame (1) and two side plates (2), the two side plates (2) are hinged to the "U"-shaped frame (1), the two side plates (2) are buckled on both sides of the "U"-shaped frame (1) to form a trough body with one side open, and the surfaces opposite to each other of the two side plates (2) are provided with a limiting mechanism connected to the "U"-shaped frame (1); Each side plate (2) is evenly distributed with connection holes (8), and positioning nails (9) are connected in the connection holes (8). The positioning nails (9) are used to connect the carbon fiber reinforced material.

8. The preparation device of composite boron carbide ceramic according to claim 7, characterized in that: Each positioning pin (9) is provided with two bosses (10), which are used to limit the insertion depth of the positioning pin (9) in the connection hole (8) and the distance between the carbon fiber reinforced material and the side plate (2), respectively.

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