A ceramic matrix composite material and a preparation method thereof

Abstract

The present invention belongs to the technical field of ceramic matrix composites, and particularly relates to a ceramic matrix composite and a preparation method thereof. In the prepreg layer of the present invention, the components and content gradient distribution of ceramic fillers alleviate the mismatch of thermal expansion coefficients between layers through the gradient distribution of ceramic components. The high melting point HfB2 in the outer layer (the first layer) and the HfB2-ZrC in the second outer layer provide excellent ablation resistance and delay matrix oxidation for the composite material through a collaborative ablation resistance component; the ZrC-SiBCN ultra-high temperature matrix in the second inner layer not only has excellent high temperature mechanical properties but also further reduces the service temperature of the thermal structure in the innermost layer (the m-th layer); furthermore, the inner layer C / SiBCN thermal structure serving at a lower temperature fully demonstrates its advantage of high specific strength. Therefore, the ceramic matrix composite provided by the present invention can not only achieve oxidation resistance and ablation resistance of the outer layer, but also achieve lightweight, high strength and high temperature resistance of the inner layer material.

Description

Technical Field

[0001] The present invention belongs to the technical field of ceramic matrix composites, and particularly relates to a ceramic matrix composite and a preparation method thereof. Background Art

[0002] When aerospace vehicles fly at high speeds in the atmosphere or near space, they often have to face extremely complex service environments, such as high-temperature oxidation, severe ablation, mechanical peeling, complex loads, etc. Ultra-high temperature ceramic matrix composites based on elements such as Ti, Zr, and Hf are often used to prepare the thermal protection systems of aerospace vehicles. Among ultra-high temperature ceramics, since a molten boron glass phase will be generated during the oxidation process of HfB2, and HfO2 has a melting point as high as 2900 °C, it is often used as an ablation-resistant matrix. Since ZrC does not have a carbothermal reduction reaction with carbon fibers and has a slightly lower density, it is often used as an ultra-high temperature thermal structure matrix. Moreover, the material system of MC-MB2 is also widely used to further enhance the mechanical properties and ablation resistance of ultra-high temperature ceramics. However, ultra-high temperature ceramics themselves are brittle, difficult to densify and sinter, and have a high density. Therefore, it is difficult for ultra-high temperature ceramic matrix composites to meet the service requirements of being lightweight and high-strength. Summary of the Invention

[0003] In view of this, the present invention provides a ceramic matrix composite and a preparation method thereof, and the ceramic matrix composite provided by the present invention has the characteristics of being lightweight and high-strength.

[0004] In order to achieve the above purposes, the present invention provides the following technical solutions:

[0005] The present invention provides a ceramic matrix composite, including n layers of prepregs; each layer of prepreg includes a reinforcement and a ceramic matrix composite unit fixed on the reinforcement; the ceramic matrix composite unit includes m layers of ceramic matrix composite layers; n≥4;

[0006] The components of the ceramic matrix composite layer include a polysilaboronitride matrix and ceramic fillers; the ceramic fillers include HfB2 and / or ZrC;

[0007] In the ceramic matrix composite, the ceramic fillers show a gradient change along one side to the other side in the thickness direction. From the first layer to the a-th layer, the mass percentage of HfB2 in the ceramic matrix composite layer decreases in a gradient of 30% to 0%, and the mass percentage of ZrC in the ceramic matrix composite layer increases in a gradient of 0 to 30%;

[0008] From the a-th layer to the b-th layer, the mass percentage of HfB2 in the ceramic matrix composite layer is 0%; the mass percentage of ZrC in the ceramic matrix composite layer decreases in a gradient of 30 to 0%;

[0009] The mass percentage of HfB2 from the b-th layer to the m-th layer in the ceramic matrix composite layer is 0%; the mass percentage of ZrC in the ceramic matrix composite layer is 0%;

[0010] The value range of a is 4 to 6; the value range of the difference between b and a is 3 to 4; the value range of the difference between m and b is 1 to 3.

[0011] Preferably, the particle sizes of the HfB2 and ZrC are independently 100 to 3000 nm.

[0012] Preferably, in the ceramic matrix composite material, the difference in the doping mass of a single ceramic filler in adjacent two ceramic matrix composite layers does not exceed 10%.

[0013] The present invention also provides a preparation method of the above-mentioned ceramic matrix composite material, including the following steps:

[0014] Disperse ceramic particles with different masses into a polysilaborazane matrix to obtain a slurry containing ceramic fillers with gradient concentrations;

[0015] Form films from the slurry containing ceramic fillers with gradient concentrations respectively to obtain film adhesives containing ceramic fillers with gradient concentrations;

[0016] Compound the reinforcement and the film adhesives of the m layers containing ceramic fillers with gradient concentrations to obtain n prepregs;

[0017] After laying the n prepregs, perform first curing and first pyrolysis in sequence to obtain a composite material blank; the laying direction is: along the thickness direction, from the first layer to the a-th layer, the mass percentage of HfB2 in the ceramic matrix composite layer decreases in a gradient of 30% to 0%, and the mass percentage of ZrC in the ceramic matrix composite layer increases in a gradient of 0 to 30%; from the a-th layer to the b-th layer, the mass percentage of HfB2 in the ceramic matrix composite layer is 0%; the mass percentage of ZrC in the ceramic matrix composite layer decreases in a gradient of 30 to 0%; from the b-th layer to the m-th layer, the mass percentage of HfB2 in the ceramic matrix composite layer is 0%; the mass percentage of ZrC in the ceramic matrix composite layer is 0%; the value range of a is 4 to 6; the value range of the difference between b and a is 3 to 4; the value range of the difference between m and b is 1 to 3;

[0018] After impregnating the composite material blank with a low-viscosity polysilaborazane, perform second curing and second pyrolysis in sequence; the normal temperature viscosity of the low-viscosity polyborosilazane is 300 to 600 mPa·S;

[0019] Repeat the impregnation, second curing and second pyrolysis 3 to 8 times to obtain the ceramic matrix composite material.

[0020] Preferably, the reinforcing body is a carbon fiber cloth containing a carbon interface; the thickness of the carbon interface is 50 to 300 nm.

[0021] Preferably, the dispersion is high-speed stirring dispersion, and the rotation speed of the high-speed stirring dispersion is 10,000 to 20,000 rpm.

[0022] Preferably, the temperature of the first curing is 150 to 300 °C, and the pressure is 2 to 4 MPa; the temperature of the first pyrolysis is 500 to 1100 °C.

[0023] Preferably, the temperature and pressure rising procedure of the first curing is as follows:

[0024] Raise the temperature from room temperature to 150 - 160 °C within 90 min and keep warm for 1 h;

[0025] Raise the temperature from 150 - 160 °C to 170 - 175 °C within 10 min and keep warm for 1 h;

[0026] Raise the temperature from 170 - 175 °C to 180 - 190 °C within 10 min and keep warm for 1 h;

[0027] Raise the temperature from 180 - 190 °C to the target temperature within 20 min and keep warm for 1 - 6 h, and apply pressure to the first curing pressure during the heat preservation period; the target temperature is 200 - 300 °C.

[0028] Preferably, the temperature rising procedure of the first pyrolysis is as follows:

[0029] Raise the temperature from room temperature to 300 °C within 1 h and keep warm for 15 min;

[0030] Raise the temperature from 300 °C to 350 °C within 15 min and keep warm for 15 min;

[0031] Raise the temperature from 350 °C to 400 °C within 15 min and keep warm for 15 min;

[0032] Raise the temperature from 400 °C to 500 °C within 1 h and keep warm for 1 - 2 h;

[0033] Raise the temperature from 500 °C to 600 °C within 1 h and keep warm for 1 - 2 h;

[0034] Raise the temperature from 600 °C to 700 °C within 1 h and keep warm for 1 - 2 h;

[0035] Raise the temperature from 700 °C to the target temperature within 3 h and keep warm for 1 - 2 h;

[0036] The target temperature is 900 - 1100 °C.

[0037] Preferably, the impregnation is pressure impregnation; the pressure of the pressure impregnation is 0.3 to 0.5 MPa; the time of the pressure impregnation is 5 to 15 min.

[0038] The present invention provides a ceramic matrix composite material, comprising n layers of prepregs; each layer of prepreg comprises a reinforcement and a ceramic matrix composite unit fixed on the reinforcement; the ceramic matrix composite unit comprises m layers of ceramic matrix composite layers; n≥4; the components of the ceramic matrix composite layer comprise a polysiloxazane matrix and ceramic fillers; the ceramic fillers comprise HfB2 and / or ZrC; in the ceramic matrix composite material, the ceramic fillers show a gradient change along one side to the other side in the thickness direction. From the first layer to the a-th layer, the mass percentage of HfB2 in the ceramic matrix composite layer decreases in a gradient of 30% to 0%, and the mass percentage of ZrC in the ceramic matrix composite layer increases in a gradient of 0 to 30%; from the a-th layer to the b-th layer, the mass percentage of HfB2 in the ceramic matrix composite layer is 0%; the mass percentage of ZrC in the ceramic matrix composite layer decreases in a gradient of 30 to 0%; from the b-th layer to the m-th layer, the mass percentage of HfB2 in the ceramic matrix composite layer is 0%; the mass percentage of ZrC in the ceramic matrix composite layer is 0%; the value range of a is 4 to 6; the value range of the difference between b and a is 3 to 4; the value range of the difference between m and b is 1 to 3. The component and content gradient distribution of the ceramic fillers in the prepreg layer of the present invention alleviates the mismatch of the coefficient of thermal expansion between layers through the gradient distribution of the ceramic components. The high melting point HfB2 in the outer layer (the first layer) and the HfB2-ZrC in the sub-outer layer provide excellent ablation resistance performance for the composite material and delay the oxidation of the matrix in a synergistic manner; the ZrC-SiBCN ultra-high temperature matrix in the sub-inner layer not only has excellent high temperature mechanical properties but also further reduces the service temperature of the thermal structure in the innermost layer (the m-th layer); further, the C / SiBCN thermal structure in the inner layer serving at a lower temperature fully demonstrates its advantage of high specific strength. Therefore, the ceramic matrix composite material provided by the present invention can not only achieve oxidation resistance and ablation resistance of the outer layer, but also achieve light weight, high strength and high temperature resistance of the inner layer material.

[0039] The data of the examples show that: the density of the ceramic matrix composite material is about 1.8 to 2 g / cm 3 , the flexural strength is 250 to 350 MPa, and the linear ablation rate at a flame temperature of 2200 °C is as low as 0.76×10 -3 ~2.1×10 -3 mm / s. Detailed implementation manners

[0040] The present invention provides a ceramic matrix composite material, comprising n layers of prepregs; each layer of prepreg comprises a reinforcement and a ceramic matrix composite unit fixed on the reinforcement; the ceramic matrix composite unit comprises m layers of ceramic matrix composite layers; n≥4;

[0041] The components of the ceramic matrix composite layer include a polysilazane matrix and ceramic fillers; the ceramic fillers include HfB2 and / or ZrC;

[0042] In the ceramic matrix composite material, the ceramic fillers show a gradient change from one side to the other along the thickness direction. From the first layer to the a-th layer, the mass percentage of HfB2 in the ceramic matrix composite layer decreases in a gradient of 30% to 0%, and the mass percentage of ZrC in the ceramic matrix composite layer increases in a gradient of 0 to 30%;

[0043] From the a-th layer to the b-th layer, the mass percentage of HfB2 in the ceramic matrix composite layer is 0%; the mass percentage of ZrC in the ceramic matrix composite layer decreases in a gradient of 30 to 0%;

[0044] From the b-th layer to the m-th layer, the mass percentage of HfB2 in the ceramic matrix composite layer is 0%; the mass percentage of ZrC in the ceramic matrix composite layer is 0%;

[0045] The value range of a is 4 to 6; the value range of the difference between b and a is 3 to 4; the value range of the difference between m and b is 1 to 3.

[0046] The ceramic matrix composite material provided by the present invention includes n layers of prepregs; each prepreg includes a reinforcement and a ceramic matrix composite unit fixed on the reinforcement; the ceramic matrix composite unit includes m layers of ceramic matrix composite layers.

[0047] In the present invention, the ceramic matrix composite unit includes m layers of ceramic matrix composite layers; the components of the ceramic matrix composite layer include a polysilazane matrix and ceramic fillers; the ceramic fillers include HfB2 and / or ZrC. In the present invention, the particle sizes of HfB2 and ZrC are independently preferably 100 to 3000 nm, more preferably 500 to 2000 nm.

[0048] In the present invention, the ceramic fillers show a gradient change from one side to the other along the thickness direction. From the first layer to the a-th layer, the mass percentage of HfB2 in the ceramic matrix composite layer decreases in a gradient of 30% to 0%, and the mass percentage of ZrC in the ceramic matrix composite layer increases in a gradient of 0 to 30%; from the a-th layer to the b-th layer, the mass percentage of HfB2 in the ceramic matrix composite layer is 0%; the mass percentage of ZrC in the ceramic matrix composite layer decreases in a gradient of 30 to 0%; from the b-th layer to the m-th layer, the mass percentage of HfB2 in the ceramic matrix composite layer is 0%; the mass percentage of ZrC in the ceramic matrix composite layer is 0%; the value range of a is 4 to 6; the value range of the difference between b and a is 3 to 4; the value range of the difference between m and b is 1 to 3.

[0049] In the present invention, taking m as 8 as an example; in the ceramic matrix composite material, along the thickness direction, from the outside to the inside, the mass percentages of HfB2 in the first layer (the outermost layer), the second layer, the third layer, the fourth layer, the fifth layer, the sixth layer, the seventh layer, and the eighth layer of ceramic matrix composite layers are preferably 30%, 20%, 10%, 0%, 0%, 0%, 0%, 0%;

[0050] The mass percentages of ZrC in the 1st to 8th layers of ceramic matrix composite layers are preferably 0%, 10%, 20%, 30%, 20%, 10%, 0%, 0%.

[0051] In the present invention, in the ceramic matrix composite material, the doping mass difference of a single ceramic filler in adjacent two layers of ceramic matrix composite layers is preferably not more than 10%, and more preferably 5 - 8%.

[0052] The present invention also provides a preparation method of the above-mentioned ceramic matrix composite material, including the following steps:

[0053] Disperse ceramic particles with different masses into a polysilazane matrix to obtain a slurry containing ceramic fillers with gradient concentrations;

[0054] Form films from the slurry containing ceramic fillers with gradient concentrations respectively to obtain film adhesives containing ceramic fillers with gradient concentrations;

[0055] Compound the reinforcement and m layers of film adhesives containing ceramic fillers with gradient concentrations to obtain n prepregs;

[0056] After laying the n prepregs, perform first curing and first pyrolysis in sequence to obtain a composite material blank; the laying direction is: along the thickness direction, from the first layer to the a-th layer, the mass percentage of HfB2 in the ceramic matrix composite layer decreases in a gradient of 30% - 0%, and the mass percentage of ZrC in the ceramic matrix composite layer increases in a gradient of 0 - 30%; from the a-th layer to the b-th layer, the mass percentage of HfB2 in the ceramic matrix composite layer is 0%; the mass percentage of ZrC in the ceramic matrix composite layer decreases in a gradient of 30 - 0%; from the b-th layer to the m-th layer, the mass percentage of HfB2 in the ceramic matrix composite layer is 0%; the mass percentage of ZrC in the ceramic matrix composite layer is 0%; the value range of a is 4 - 6; the value range of the difference between b and a is 3 - 4; the value range of the difference between m and b is 1 - 3;

[0057] After impregnating the composite material blank with a low-viscosity polysilazane, perform second curing and second pyrolysis in sequence; the normal temperature viscosity of the low-viscosity polyborosilazane is 300 - 600 mPa·S;

[0058] Repeat the impregnation, second curing, and second pyrolysis 3 - 8 times to obtain the ceramic matrix composite material.

[0059] In the present invention, ceramic particles of different qualities are dispersed into a polysilazane matrix to obtain a slurry containing ceramic fillers with a gradient concentration.

[0060] In the present invention, the polysilazane matrix is preferably obtained by mixing liquid polysilazane and solid polysilazane. In the present invention, the viscosity of the polysilazane matrix is preferably 5×10 3 ~3×10 5 Pa·S, and more preferably (5~10)×10 4 mPa·S.

[0061] In the present invention, the dispersion is preferably as follows: after mixing ceramic particles of different qualities and liquid polysilazane, solid polysilazane is added thereto and heated for dissolution to obtain a slurry containing ceramic fillers with a gradient concentration.

[0062] In the present invention, the temperature for heating and dissolution is preferably 50~70°C, and more preferably 60°C.

[0063] In the present invention, the dispersion is preferably high-speed stirring dispersion; the rotation speed of the high-speed stirring dispersion is 10000~20000 rpm, and the time is 30 min.

[0064] After obtaining the slurry containing ceramic fillers with a gradient concentration, in the present invention, the slurry containing ceramic fillers with a gradient concentration is formed into films respectively to obtain a film adhesive containing ceramic fillers with a gradient concentration.

[0065] In the present invention, the film formation is preferably knife coating film formation.

[0066] After obtaining the film adhesive containing ceramic fillers with a gradient concentration, in the present invention, a reinforcing body and m film adhesives containing ceramic fillers with a gradient concentration are compounded to obtain n prepregs;

[0067] In the present invention, the compounding method is preferably adhesion. In the present invention, the adhesion is preferably roll pressing adhesion; the temperature of the roll for roll pressing adhesion is preferably 80~100°C.

[0068] In the present invention, the reinforcing body is a modified carbon fiber cloth; the modified carbon fiber cloth includes a carbon fiber cloth and a carbon layer on the surface of the carbon fiber cloth. The carbon fiber cloth is preferably a UD cloth, plain weave cloth, twill weave cloth or satin weave cloth of commercial T or M series carbon fibers, and more preferably a plain weave cloth, twill weave cloth or satin weave cloth of T300 grade carbon fibers. In the present invention, the thickness of the carbon interface is preferably 50~300 nm, and more preferably 100~200 nm.

[0069] In the present invention, the preparation of the modified carbon fiber cloth is preferably as follows: using propylene as a carbon source, chemical deposition is carried out on the surface of the carbon fiber cloth to obtain a carbon fiber cloth with a carbon interface.

[0070] In the present invention, the conditions for chemical deposition include: the deposition temperature is preferably 950 °C, the pressure is preferably 1 kPa, and the residence time is preferably 3 s.

[0071] In the present invention, after the compounding, it is preferably further included to cool the compounded prepreg and then bond it with the release paper for standby.

[0072] After obtaining the prepreg, in the present invention, the n prepregs are laid up and then subjected to first curing and first pyrolysis in sequence to obtain a composite blank; the laying direction is: along the thickness direction, from the first layer to the a-th layer, the mass percentage of HfB2 in the ceramic matrix composite layer decreases in a gradient of 30% to 0%, and the mass percentage of ZrC in the ceramic matrix composite layer increases in a gradient of 0 to 30%; from the a-th layer to the b-th layer, the mass percentage of HfB2 in the ceramic matrix composite layer is 0%; the mass percentage of ZrC in the ceramic matrix composite layer decreases in a gradient of 30 to 0%; from the b-th layer to the m-th layer, the mass percentage of HfB2 in the ceramic matrix composite layer is 0%; the mass percentage of ZrC in the ceramic matrix composite layer is 0%; the value range of a is 4 to 6; the value range of the difference between b and a is 3 to 4; the value range of the difference between m and b is 1 to 3.

[0073] In the present invention, the temperature of the first curing is preferably 150 to 300 °C, more preferably 150 to 280 °C; the pressure is preferably 2 to 4 MPa, more preferably 2.5 to 3.5 MPa; the time is preferably 4 to 9 h, more preferably 6 to 8 h. In the present invention, the temperature and pressure rising procedure of the first curing is preferably: rising from room temperature to 150 to 160 °C within 90 min and holding for 1 h; rising from 150 to 160 °C to 170 to 175 °C within 10 min and holding for 1 h; rising from 170 to 175 °C to 180 to 190 °C within 10 min and holding for 1 h; rising from 180 to 190 °C to the target temperature within 20 min and holding for 1 to 6 h, and pressurizing to the pressure of the first curing during the holding period; the target temperature is 200 to 300 °C. In the present invention, the first curing is preferably carried out in a flat vulcanizer or an oven.

[0074] In the present invention, the temperature of the first pyrolysis is preferably 500 to 1100 °C, more preferably 1000 °C; the pressure is preferably 3 MPa; the time is preferably 5 to 10 h.

[0075] In the present invention, the temperature rising procedure of the first pyrolysis is preferably: rising from room temperature to 300 °C within 1 h and holding for 15 min;

[0076] rising from 300 °C to 350 °C within 15 min and holding for 15 min;

[0077] rising from 350 °C to 400 °C within 15 min and holding for 15 min;

[0078] Heat up from 400 °C to 500 °C within 1 h and keep the temperature for 1 - 2 h;

[0079] Heat up from 500 °C to 600 °C within 1 h and keep the temperature for 1 - 2 h;

[0080] Heat up from 600 °C to 700 °C within 1 h and keep the temperature for 1 - 2 h;

[0081] Heat up from 700 °C to the target temperature within 3 h and keep the temperature for 1 - 2 h;

[0082] The target temperature is 900 - 1100 °C.

[0083] After obtaining the composite material blank, the present invention impregnates the composite material blank with low-viscosity polysilaboronitride, and then performs second curing and second pyrolysis in sequence; repeat the impregnation, second curing and second pyrolysis 3 - 8 times to obtain the ceramic matrix composite material.

[0084] In the present invention, the normal temperature viscosity of the low-viscosity polysilaboronitride is 300 - 600 mPa·S, and more preferably 400 - 500 mPa·S.

[0085] In the present invention, the impregnation is preferably pressure impregnation; the pressure of the pressure impregnation is preferably 0.3 - 0.5 MPa, more preferably 0.4 MPa; the time of the pressure impregnation is preferably 10 min.

[0086] In the present invention, the number of repetitions of the impregnation, second curing and second pyrolysis is preferably 3 - 8 times.

[0087] In the present invention, a solvent-free high-viscosity polysilaboronitride film is used to load ceramic particles. After the prepreg is cured, the ceramization yield is high. The subsequent densification of the prepared gradient ceramic matrix composite material can be achieved only by 3 - 8 rounds of liquid polysilaboronitride impregnation and pyrolysis. Due to the higher ceramization yield, low-cost polysilaboronitride and no use of RMI for subsequent densification, compared with the existing gradient ceramic matrix composite material preparation technology, the present invention has a shorter preparation time, lower cost and more excellent high-temperature mechanical properties. Compared with the existing technologies that achieve the integration of light weight, high strength and anti-ablative performance by coating method or layered matrix method, the present invention greatly eliminates the thermal expansion and thermal stress mismatch between different functional layers due to the gradient distribution of components.

[0088] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0089] Example 1

[0090] (1) Use T300-1k plain weave fabric as the reinforcement, and its areal density is 150 g / m 2Using propylene as the gas source, the carbon fiber plain cloth was subjected to pyrolytic carbon (PyC) interfacial deposition treatment at a deposition temperature of 950 °C, a pressure of 1 kPa, and a residence time of 3 s. The average thickness of the interface of the deposited fiber cloth was about 150 nm, and the areal density after deposition was about 200 g / m 2 ;

[0091] (2) Using a high-speed shear emulsifying disperser, ZrC with an average particle size of 500 nm and HfB2 were dispersed into liquid polysilaboronitride at a rotation speed of 20,000 rpm for 30 min. Then, solid polysilaboronitride (with a mass of 40% of the liquid polysilaboronitride) was mechanically stirred and heated to dissolve (dissolution temperature: 60 °C) into the liquid polysilaboronitride, and then it was knife-coated into a film and cooled to room temperature to obtain a glue film.

[0092] The prepared glue films respectively contained 30 wt% HfB2, 20 wt% HfB2 - 10 wt% ZrC, 10 wt% HfB2 - 20 wt% ZrC, 30 wt% ZrC, 20 wt% ZrC, 10 wt% ZrC ceramic particles. At the same time, a pure SiBCN glue film without loaded ceramic particles was prepared.

[0093] (3) Using the heating roll method, two layers of glue films and one layer of plain cloth with a carbon interface were bonded into a prepreg. The heating temperature was 80 °C, the linear speed of the pressure roller machine was 4 m / min. After the bonded prepreg was cooled by air blowing, it was bonded with release paper, and the prepreg was wound up and stored frozen for standby.

[0094] (4) The prepared prepreg was laid up, and the mass percentage distribution of each layer of glue film components was as follows:

[0095] The first layer (the outermost ablation layer): Cf / SiBCN - 30 wt% HfB2

[0096] The second layer: Cf / SiBCN - 20 wt% HfB2 - 10 wt% ZrC

[0097] The third layer: Cf / SiBCN - 10 wt% HfB2 - 20 wt% ZrC

[0098] The fourth layer: Cf / SiBCN - 30 wt% ZrC

[0099] The fifth layer: Cf / SiBCN - 20 wt% ZrC

[0100] The sixth layer: Cf / SiBCN - 10 wt% ZrC

[0101] The seventh layer: Cf / SiBCN

[0102] The eighth layer: Cf / SiBCN

[0103] The ninth layer: Cf / SiBCN

[0104] The tenth layer: Cf / SiBCN

[0105] (5) The composite material after layup is placed on a flat vulcanizing machine and cured under pressure and heat. The curing regime is as follows: heat up to 150 °C within 90 min and hold for 1 h, apply pressure up to 2 MPa during the holding period; heat up from 150 °C to 170 °C within 10 min and hold for 1 h; heat up from 170 °C to 180 °C within 10 min and hold for 1 h; heat up from 180 °C to 200 °C within 20 min and hold for 2 h, the constant pressure value is 4 MPa during the holding period at 200 °C; heat up from 200 °C to 280 °C within 1 h and then cure and hold for 1 h, and finally slowly cool to room temperature.

[0106] (6) The cured composite material is placed in a hot-pressing sintering furnace for pyrolysis. The pyrolysis regime is as follows: apply pressure up to 3 MPa, heat up to 300 °C within 1 h and hold for 15 min; heat up to 350 °C within 15 min and hold for 15 min; heat up to 400 °C within 15 min and hold for 15 min; heat up to 500 °C within 1 h and hold for 1 h; heat up to 600 °C within 1 h and hold for 1 h; heat up to 700 °C within 1 h and hold for 1 h; heat up to 900 °C within 3 h and hold for 1 h; cool down to 600 °C within 3 h and hold for 1 h; cool down to 400 °C within 1 h and hold for 1 h; then cool down to room temperature within 10 h.

[0107] (7) The composite material after pyrolysis is placed in a heating and pressure impregnation tank to impregnate with low-viscosity (300 - 600 mPa·S) polyborosilazane. The heating temperature is 100 °C, the pressure is 0.3 - 0.5 MPa, and the impregnation time is 10 min. After impregnation, the sample is taken out and wrapped with tin foil and placed in an oven for curing. The curing temperature regime is the same as that in step (5). After curing, the composite material is pyrolyzed at high temperature in an atmosphere furnace, and the pyrolysis temperature regime is the same as that in step (6).

[0108] (8) Repeat step 7 for a total of 6 times.

[0109] Example 2

[0110] (1) Use the T700 carbon fiber 12k spread fabric as the reinforcement, and its areal density is 200 g / m 2 . Use propylene as the gas source to conduct pyrolytic carbon (PyC) interface deposition treatment on the carbon fiber plain weave fabric. The deposition temperature is 950 °C, the pressure is 1 kPa, and the residence time is 3 s. The average thickness of the fiber cloth interface after deposition is about 150 nm, and the areal density after deposition is about 200 g / m 2 ;

[0111] (2) Use a high-speed shear emulsifying and dispersing machine to disperse ZrC and HfB2 with an average particle size of 500 nm into liquid polysilaboronitride at a rotation speed of 20,000 rpm for 30 minutes. Then, mechanically stir and heat to dissolve solid polysilaboronitride (with a mass of 40% of the liquid polysilaboronitride) and dicumyl peroxide (with a mass of 1% of the liquid polysilaboronitride) (dissolution temperature is 60 °C) into the liquid polysilaboronitride, and then scrape it into a film and cool it to room temperature to obtain a glue film.

[0112] The prepared glue films respectively contain 30 wt% HfB2, 20 wt% HfB2 - 10 wt% ZrC, 10 wt% HfB2 - 20 wt% ZrC, 30 wt% ZrC, 20 wt% ZrC, 10 wt% ZrC ceramic particles. At the same time, a pure SiBCN glue film without loaded ceramic particles was prepared.

[0113] (3) Use the heating roll method to bond two layers of glue films and a plain weave cloth with a carbon-containing interface into a prepreg. The heating temperature is 80 °C, the linear speed of the pressure roller machine is 4 m / min. After the bonded prepreg is cooled by blowing air, it is bonded with release paper, and the prepreg is wound up and stored frozen for standby.

[0114] (4) Lay up the prepared prepreg. The mass percentage distribution of each layer of glue film components is as follows:

[0115] The first layer (the outermost ablation layer): Cf / SiBCN - 30 wt% HfB2

[0116] The second layer: Cf / SiBCN - 20 wt% HfB2 - 10 wt% ZrC

[0117] The third layer: Cf / SiBCN - 10 wt% HfB2 - 20 wt% ZrC

[0118] The fourth layer: Cf / SiBCN - 30 wt% ZrC

[0119] The fifth layer: Cf / SiBCN - 20 wt% ZrC

[0120] The sixth layer: Cf / SiBCN - 10 wt% ZrC

[0121] The seventh layer: Cf / SiBCN

[0122] The eighth layer: Cf / SiBCN

[0123] The ninth layer: Cf / SiBCN

[0124] The tenth layer: Cf / SiBCN

[0125] (5) The composite material after layering is placed on a flat vulcanizing machine and cured under pressure and heat. The curing regime is as follows: Heat up to 150 °C within 90 min and hold for 1 h, apply pressure up to 2 MPa during the holding period; heat up from 150 °C to 170 °C within 10 min and hold for 1 h; heat up from 170 °C to 180 °C within 10 min and hold for 1 h; heat up from 180 °C to 200 °C within 20 min and hold for 2 h, the constant pressure value is 4 MPa during the holding period at 200 °C, and finally cool down slowly to room temperature.

[0126] (6) The cured composite material is placed in a hot-pressing sintering furnace for pyrolysis. The pyrolysis regime is as follows: Apply pressure up to 3 MPa, heat up to 300 °C within 1 h and hold for 15 min; heat up within 15 min to 350 °C and hold for 15 min; heat up within 15 min to 400 °C and hold for 15 min; heat up to 500 °C within 1 h and hold for 1 h; heat up to 600 °C within 1 h and hold for 1 h; heat up to 700 °C within 1 h and hold for 1 h; heat up to 1000 °C within 3 h and hold for 1 h; cool down to 600 °C within 3 h and hold for 1 h; cool down to 400 °C within 1 h and hold for 1 h; then cool down to room temperature within 10 h.

[0127] (7) The composite material after pyrolysis is placed in a heating and pressure impregnation tank to impregnate with low-viscosity (300 - 600 mPa·S) polyborosilazane. The heating temperature is 100 °C, the pressure is 0.3 - 0.5 MPa, and the impregnation time is 10 min. After impregnation, take out the sample and wrap it with tin foil and place it in an oven for curing. The curing temperature regime is the same as in step (5). After curing, perform high-temperature pyrolysis on the composite material using an atmosphere furnace. The pyrolysis temperature regime is the same as in step (6).

[0128] (8) Repeat step 7 three times in total.

[0129] The density of the lightweight, high-strength and anti-ablative gradient ceramic matrix composite material prepared in Example 1 is 2.06 g / cm3, the room-temperature flexural strength can reach 312 MPa, and the room-temperature tensile strength can reach 277 MPa; at a flame temperature of 2200 °C, the average linear ablation rate in 30 s is only 0.82×10 -3 mm / s.

[0130] The density of the lightweight, high-strength and anti-ablative gradient ceramic matrix composite material prepared in Example 2 is 1.92 g / cm3, the room-temperature flexural strength can reach 272 MPa, and the room-temperature tensile strength can reach 296 MPa; at a flame temperature of 2200 °C, the average linear ablation rate in 30 s is 2.1×10 -3 mm / s.

[0131] Example 3

[0132] Example 3 is different from Example 1 in that: in step (2), the average particle size of the ZrC and HfB2 ceramic powders used is 2 μm, and mechanical stirring (stirring speed is 600 rpm) is used to disperse the ceramic particles in the liquid polyborosilazane.

[0133] The density of the lightweight, high-strength and anti-ablative gradient ceramic matrix composite prepared in this example is 2.11 g / cm3, the room temperature bending strength can reach 281 MPa, and the room temperature tensile strength can reach 249 MPa; at a flame temperature of 2200 °C, the average linear ablation rate in 30 s is 0.76×10 -3 mm / s.

[0134] Comparative Example 1

[0135] (1) T300-1k plain weave fabric is used as the reinforcement, and its areal density is 150 g / m 2 . Propylene is used as the gas source for PyC interface deposition treatment of the carbon fiber plain weave fabric. The deposition temperature is 950 °C, the pressure is 1 kPa, and the residence time is 3 s. The average thickness of the interface of the deposited fiber fabric is about 150 nm, and the areal density after deposition is about 200 g / m 2 .

[0136] (2) Mechanical stirring is used to disperse ZrC with an average particle size of 2 μm into the liquid polyborosilazane, and its mass fraction is 30%. Then, solid polyborosilazane (with a mass of 40% of the liquid polyborosilazane) is mechanically stirred and heated to dissolve (dissolution temperature is 60 °C) into the liquid polyborosilazane, and then it is scrape-coated into a film and cooled to room temperature to obtain a ZrC-containing film with 30 wt%.

[0137] (3) The heating roll method is used to bond two layers of the film and one layer of the plain weave fabric with a carbon interface into a prepreg. The heating temperature is 80 °C, the linear speed of the calender is 4 m / min. After the bonded prepreg is cooled by air blowing, it is bonded to the release paper, and the prepreg is wound up and stored frozen for later use.

[0138] (4) The prepared prepreg is laid up, and 10 layers are laid.

[0139] (5) The laminated composite material is placed on a flat vulcanizer and pressurized and heated for curing. The curing regime is: heated to 150 °C within 90 min and held for 1 h, pressurized to 2 MPa during the holding period; heated from 150 °C to 170 °C within 10 min and held for 1 h; heated from 170 °C to 180 °C within 10 min and held for 1 h; heated from 180 °C to 200 °C within 20 min and held for 2 h, the constant pressure value during the holding period at 200 °C is 4 MPa; heated from 200 °C to 280 °C within 1 h and then cured and held for 1 h, and finally slowly cooled to room temperature.

[0140] (6) Place the cured composite material in a hot press sintering furnace for pyrolysis. The pyrolysis regime is as follows: pressurize to 3 MPa, heat up to 300 °C within 1 h and hold for 15 min; heat up to 350 °C within 15 min and hold for 15 min; heat up to 400 °C within 15 min and hold for 15 min; heat up to 500 °C within 1 h and hold for 1 h; heat up to 600 °C within 1 h and hold for 1 h; heat up to 700 °C within 1 h and hold for 1 h; heat up to 900 °C within 3 h and hold for 1 h; cool down to 600 °C within 3 h and hold for 1 h; cool down to 400 °C within 1 h and hold for 1 h; then cool down to room temperature within 10 h.

[0141] (7) Place the pyrolyzed composite material in a heating and pressure impregnation tank to impregnate with low-viscosity (300 - 600 mPa·S) polyborosilazane. The heating temperature is 100 °C, the pressure is 0.3 - 0.5 MPa, and the impregnation time is 10 min. After impregnation, take out the sample and wrap it with tin foil and place it in an oven for curing. The curing temperature regime is the same as that in step (5). After curing, perform high-temperature pyrolysis on the composite material using an atmosphere furnace. The pyrolysis temperature regime is the same as that in step (6).

[0142] (8) Repeat step 7 six times.

[0143] The density of the C / SiBCN-ZrC ceramic matrix composite material prepared in this comparative example is 2.18 g / cm 3 , the room temperature flexural strength can reach 321 MPa, and the room temperature tensile strength can reach 264 MPa; at a flame temperature of 2200 °C, the average linear ablation rate within 30 s is 9.4×10 -3 mm / s.

[0144] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A ceramic matrix composite material, characterized in that, It includes n layers of prepregs; each layer of prepreg includes a reinforcement and a ceramic matrix composite unit fixed on the reinforcement; the ceramic matrix composite unit includes m layers of ceramic matrix composite layers; n≥4; the reinforcement is a modified carbon fiber cloth, and the modified carbon fiber cloth includes a carbon fiber cloth and a carbon layer on the surface of the carbon fiber cloth; the thickness of the carbon layer is 50 - 300 nm; The components of the ceramic matrix composite layer include a polysilazane matrix and ceramic fillers; the ceramic fillers include HfB2 and / or ZrC; In the ceramic matrix composite material, the ceramic fillers show a gradient change from one side to the other along the thickness direction. From the first layer to the a-th layer, the mass percentage of HfB2 in the ceramic matrix composite layer decreases in a gradient of 30% - 0%, and the mass percentage of ZrC in the ceramic matrix composite layer increases in a gradient of 0 - 30%; From the a-th layer to the b-th layer, the mass percentage of HfB2 in the ceramic matrix composite layer is 0%; the mass percentage of ZrC in the ceramic matrix composite layer decreases in a gradient of 30 - 0%; From the b-th layer to the m-th layer, the mass percentage of HfB2 in the ceramic matrix composite layer is 0%; The mass percentage of ZrC in the ceramic matrix composite layer is 0%; The value range of a is 4 - 6; the value range of the difference between b and a is 3 - 4; the value range of the difference between m and b is 1 - 3.

2. The ceramic matrix composite material according to claim 1, characterized in that The particle sizes of HfB2 and ZrC are independently 100 - 3000 nm.

3. The ceramic matrix composite material according to claim 1 or 2, characterized in that In the ceramic matrix composite material, the difference in the doping mass of a single ceramic filler between adjacent two ceramic matrix composite layers does not exceed 10%.

4. The preparation method of the ceramic matrix composite material according to any one of claims 1 to 3, characterized in that, It includes the following steps: Disperse ceramic particles with different masses into the polysilazane matrix to obtain a slurry containing ceramic fillers with gradient concentrations; Form films from the slurry containing ceramic fillers with gradient concentrations respectively to obtain adhesive films containing ceramic fillers with gradient concentrations; Composite the reinforcement and m adhesive films containing ceramic fillers with gradient concentrations to obtain n prepregs; After laying the n prepregs, perform first curing and first pyrolysis in sequence to obtain a composite material blank; the laying direction is: along the thickness direction, from the first layer to the a-th layer, the mass percentage of HfB2 in the ceramic matrix composite layer decreases in a gradient of 30% - 0%, and the mass percentage of ZrC in the ceramic matrix composite layer increases in a gradient of 0 - 30%; from the a-th layer to the b-th layer, the mass percentage of HfB2 in the ceramic matrix composite layer is 0%; the mass percentage of ZrC in the ceramic matrix composite layer decreases in a gradient of 30 - 0%; from the b-th layer to the m-th layer, the mass percentage of HfB2 in the ceramic matrix composite layer is 0%; the mass percentage of ZrC in the ceramic matrix composite layer is 0%; the value range of a is 4 - 6; the value range of the difference between b and a is 3 - 4; the value range of the difference between m and b is 1 - 3; After impregnating the composite material blank with a low-viscosity polysilazane, perform second curing and second pyrolysis in sequence; the normal-temperature viscosity of the low-viscosity polysilazane is 300 - 600 mPa·S; Repeat the impregnation, second curing and second pyrolysis 3 - 8 times to obtain the ceramic matrix composite material.

5. The preparation method according to claim 4, characterized in that, The dispersion is carried out by high-speed stirring dispersion, and the rotation speed of the high-speed stirring dispersion is 10,000 - 20,000 rpm.

6. The preparation method according to claim 4, characterized in that, The temperature of the first curing is 150 - 300 °C, and the pressure is 2 - 4 MPa; the temperature of the first pyrolysis is 500 - 1100 °C.

7. The preparation method according to claim 4 or 6, characterized in that, The temperature and pressure increasing program of the first curing is as follows: Heat up from room temperature to 150 - 160 °C within 90 min and keep the temperature for 1 h; Heat up from 150 - 160 °C to 170 - 175 °C within 10 min and keep the temperature for 1 h; Heat up from 170 - 175 °C to 180 - 190 °C within 10 min and keep the temperature for 1 h; Heat up from 180 - 190 °C to the target temperature within 20 min and keep the temperature for 1 - 6 h. During the heat preservation period, pressurize to the pressure of the first curing; the target temperature is 200 - 300 °C.

8. The preparation method according to claim 4 or 6, characterized in that, The temperature increasing program of the first pyrolysis is as follows: Heat up from room temperature to 300 °C within 1 h and keep the temperature for 15 min; Heat up from 300 °C to 350 °C within 15 min and keep the temperature for 15 min; Heat up from 350 °C to 400 °C within 15 min and keep the temperature for 15 min; Heat up from 400 °C to 500 °C within 1 h and keep the temperature for 1 - 2 h; Heat up from 500 °C to 600 °C within 1 h and keep the temperature for 1 - 2 h; Heat up from 600 °C to 700 °C within 1 h and keep the temperature for 1 - 2 h; Heat up from 700 °C to the target temperature within 3 h and keep the temperature for 1 - 2 h; The target temperature is 900 - 1100 °C.

9. The preparation method according to claim 4, characterized in that, The impregnation is carried out under pressure; the pressure of the pressure impregnation is 0.3 - 0.5 MPa; the time of the pressure impregnation is 5 - 15 min.