Preparation method of high-temperature-resistant composite ceramic material

Abstract

The invention discloses a preparation method of a high-temperature-resistant composite ceramic material, and relates to the field of composite ceramic materials. When the high-temperature-resistant composite ceramic material is prepared, boron nitride nanosheets are dispersed, then are subjected to electrical negative treatment by using metal lithium particles, and then react with oxygen to obtain hydroxylated nano boron nitride; the preparation method comprises the following steps: reacting mullite whiskers with hydroxymethyl triethoxy silane to obtain modified mullite whiskers; initiating and coupling chloromethyl trichlorosilane through magnesium powder to prepare polycarbosilane; polycarbosilane and maleic anhydride are subjected to a reaction, and modified polycarbosilane is prepared; and uniformly mixing the modified polycarbosilane, a polystyrene pore-foaming agent, hydroxylated nano boron nitride and the modified mullite whisker, and calcining to obtain the high-temperature-resistant composite ceramic material. The high-temperature-resistant composite ceramic material prepared by the invention has excellent high temperature resistance, heat preservation property and mechanical property.

Description

Technical Field

[0001] The present invention relates to the field of composite ceramic materials, and specifically to a preparation method of a high-temperature resistant composite ceramic material. Background Art

[0002] Porous ceramic matrix composites are regarded as an ideal alternative material for porous medium transpiration cooling materials due to their excellent properties, including low density, low thermal expansion coefficient, excellent thermal shock resistance, high-temperature oxidation resistance, etc. Among them, silicon carbide-based porous ceramics have received extensive attention from researchers in this field due to their excellent properties such as good mechanical properties, thermal shock resistance, and corrosion resistance. Silicon carbide ceramics, also known as carborundum, are covalent inorganic substances. Their composition forms a regular tetrahedral crystal structure similar to diamond with equal amounts of silicon and carbon. The unique structure endows silicon carbide ceramics with excellent properties. Silicon carbide ceramics are widely used in extreme places such as aerospace engines, thermal protection material systems, hypersonic propulsion systems, and nuclear energy engineering due to their excellent high-temperature resistance, oxidation resistance, wear resistance, thermal stability, and chemical erosion resistance. However, at the same time, due to the inherent chemical bond characteristics of ceramic materials, it is difficult for dislocation movement to occur in their internal microstructure, resulting in relatively large inherent brittleness of ceramic materials. Therefore, the present invention prepares a high-temperature resistant composite ceramic material with excellent mechanical properties. Summary of the Invention

[0003] The purpose of the present invention is to provide a preparation method of a high-temperature resistant composite ceramic material to solve the problems existing in the prior art.

[0004] To solve the above technical problems, the present invention provides the following technical solutions: A preparation method of a high-temperature resistant composite ceramic material, wherein the high-temperature resistant composite ceramic material is obtained by calcining a mixture of modified polycarbosilane, polystyrene pore-forming agent, hydroxylated nano-boron nitride, and modified mullite whiskers.

[0005] As an optimization, the polystyrene pore-forming agent is from Dongguan Baolimei Plastic Raw Material Co., Ltd.

[0006] As an optimization, the modified polycarbosilane is prepared by coupling chloromethyltrichlorosilane with magnesium powder and then reacting with maleic anhydride.

[0007] As an optimization, the nickel acetylacetonate dihydrate is from Wuhan Chengtian Fine Chemical Co., Ltd.

[0008] As an optimization, the hydroxylated nano-boron nitride is obtained by dispersing boron nitride nanosheets, electro-negativizing them with lithium metal particles, and then reacting with oxygen.

[0009] As an optimization, the boron nitride nanosheets are from Hubei Xinyuhong Biomedical Technology Co., Ltd.

[0010] As an optimization, the modified mullite whiskers are obtained by reacting mullite whiskers with hydroxymethyltriethoxysilane.

[0011] As an optimization, the mullite whiskers are of 800-mesh type and are from Shijiazhuang Ultra-fine New Material Technology Co., Ltd.

[0012] As an optimization, the preparation method of the high-temperature resistant composite ceramic material comprises the following preparation steps: (1) Mix boron nitride nanosheets and N-methylpyrrolidone at a mass ratio of 1:(900 - 1100), ultrasonically crush for 47 - 49 h, then centrifuge, take the supernatant and let it stand for sedimentation, filter with a 0.05 - 0.15 μm filter membrane, wash with absolute ethanol 3 - 5 times, and dry at 75 - 85 °C for 23 - 25 h to obtain dispersed nano boron nitride; Mix the dispersed nano boron nitride and tetrahydrofuran at a mass ratio of 1:(350 - 450), ultrasonically treat for 55 - 65 min, under anhydrous and anaerobic conditions at -79 - 77 °C, add liquid nitrogen, stir at 400 - 600 r / min for 55 - 65 min, add lithium metal particles 1.3 - 1.5 times the mass of the dispersed nano boron nitride, continue stirring for 1 - 2 h, introduce oxygen and continue stirring for 5 - 7 h, uniformly add deionized water 2 - 4 times the mass of the dispersed nano boron nitride within 1 - 3 h, continue stirring for 55 - 65 min, filter with a filter membrane, wash with tetrahydrofuran, chloroform, absolute ethanol and deionized water 3 - 5 times respectively, and dry at 75 - 85 °C for 23 - 25 h to obtain hydroxylated nano boron nitride; (2) Mix mullite whiskers, hydroxymethyltriethoxysilane and an ethanol solution at a mass ratio of 1:(0.04 - 0.06):(35 - 45), add acetic acid to adjust the pH to 3 - 4, stir at 20 - 30 °C and 100 - 200 rpm for 5 - 7 h, then filter, wash with absolute ethanol and deionized water 3 - 5 times respectively, and dry at 75 - 85 °C for 23 - 25 h to obtain modified mullite whiskers; (3) Mix chloromethyltrichlorosilane, magnesium powder, and tetrahydrofuran in a mass ratio of 1:(0.4 - 0.6):(10 - 20), stir at 35 - 45 °C and 100 - 200 rpm for 1 - 2 h in a nitrogen atmosphere, raise the temperature to 55 - 65 °C and keep warm for 11 - 13 h, cool down to -1 - 1 °C, add lithium aluminum hydride in an amount of 0.02 - 0.04 times the mass of chloromethyltrichlorosilane, raise the temperature to 55 - 65 °C and keep warm for 11 - 13 h, quench with hydrochloric acid solution, add n-hexane and deionized water, let it stand for liquid separation and then filter. Wash the lower layer with 4 - 6 mol / L hydrochloric acid solution 3 - 5 times, dry with anhydrous sodium sulfate and then perform rotary evaporation to obtain polycarbosilane; Mix polycarbosilane, maleic anhydride, chloroplatinic acid, and xylene in a mass ratio of 1:(0.04 - 0.06):(0.2 - 0.3):(15 - 25), stir at 75 - 85 °C and 300 - 400 rpm for 2 - 4 h in an argon atmosphere, naturally cool to room temperature and then perform vacuum rotary evaporation, grind and sieve, and keep warm at 95 - 105 °C for 2 - 4 h to obtain modified polycarbosilane; (4) Mix modified polycarbosilane, polystyrene pore-forming agent, hydroxylated nano-boron nitride, modified mullite whiskers, and absolute ethanol in a mass ratio of 1:(0.07 - 0.09):(0.02 - 0.03):(0.01 - 0.03):(1 - 2), ultrasonicate for 25 - 35 min, ball mill at 250 - 350 r / min for 5 - 7 h, stir in a water bath at 85 - 95 °C until viscous, dry at 75 - 85 °C for 11 - 13 h, grind and sieve through a 35 - 45 mesh sieve, load into a mold, heat up to 1400 - 1600 °C at 1 - 3 °C / min and keep warm at 35 - 45 MPa for 55 - 65 min in a nitrogen atmosphere, cool down to room temperature with the furnace, take out and polish to obtain a high-temperature resistant composite ceramic material.

[0013] As an optimization, the ultrasonic crushing condition in step (1) is 450 - 460 W.

[0014] As an optimization, the sedimentation time in step (1) is 23 - 25 h.

[0015] As an optimization, the amount of liquid nitrogen added in step (1) is 900 - 1000 times the mass of dispersed nano-boron nitride.

[0016] As an optimization, the filter membrane size in step (1) is 0.05 - 0.15 μm.

[0017] As an optimization, the mass fraction of the ethanol solution in step (2) is 90% - 100%.

[0018] As an optimization, the concentration of the hydrochloric acid solution used for quenching in step (3) is 2 - 4 mol / L.

[0019] As an optimization, the particle size of the grinding and sieving in step (3) is 40 - 60 mesh.

[0020] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: When preparing the high-temperature resistant composite ceramic material of the present invention, boron nitride nanosheets are dispersed, electro-negativized with lithium metal particles and then reacted with oxygen to obtain hydroxylated nano-boron nitride; mullite whiskers and hydroxymethyltriethoxysilane are reacted to obtain modified mullite whiskers; chloromethyltrichlorosilane is coupled through magnesium powder initiation to obtain polycarbosilane; then polycarbosilane is reacted with maleic anhydride to obtain modified polycarbosilane; the modified polycarbosilane, polystyrene pore-forming agent, hydroxylated nano-boron nitride and modified mullite whiskers are mixed and calcined to obtain the high-temperature resistant composite ceramic material.

[0021] First of all, boron nitride nanosheets are dispersed, electro-negativized with lithium metal particles and then reacted with oxygen to obtain hydroxylated nano-boron nitride; mullite whiskers and hydroxymethyltriethoxysilane are reacted to obtain modified mullite whiskers; the thermal expansion coefficients of boron nitride nanosheets and mullite whiskers are close to those of silicon carbide ceramics. As reinforcing phases, they can avoid thermal stress caused by mismatched thermal expansion coefficients; the layered structure of boron nitride nanosheets can prevent or deflect cracks. When the material is stressed, mullite whiskers can play a "bridging" role, further increasing the difficulty of crack propagation and improving the mechanical properties of the high-temperature resistant composite ceramic material; the boron nitride nanosheets and mullite whiskers are respectively hydroxylated and modified, and undergo transesterification reaction with maleic anhydride to form ester groups, promoting dispersion crosslinking and further improving the mechanical properties of the high-temperature resistant composite ceramic material.

[0022] Secondly, chloromethyltrichlorosilane is coupled through magnesium powder initiation to obtain polycarbosilane; then polycarbosilane is reacted with maleic anhydride to obtain modified polycarbosilane; the modified polycarbosilane, polystyrene pore-forming agent, hydroxylated nano-boron nitride and modified mullite whiskers are mixed and calcined to obtain the high-temperature resistant composite ceramic material; maleic anhydride is grafted onto polycarbosilane through hydrosilylation, and undergoes transesterification reaction with hydroxylated nano-boron nitride and modified mullite whiskers. The formed ester groups are converted into small molecule gases and overflow during calcination, enriching the pore structure and improving the heat preservation performance of the high-temperature resistant composite ceramic material; at the same time, polystyrene is doped as a pore-forming agent and decomposed into low molecular weight organic gases and escapes during sintering, further improving the heat preservation performance of the high-temperature resistant composite ceramic material; the existence of pores usually reduces the mechanical properties of ceramics. The present invention enriches the pore structure on the basis of retaining high bonding strength, improving the comprehensive performance of the high-temperature resistant composite ceramic material. Specific embodiments

[0023] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention. Example 1:

[0024] A preparation method of a high-temperature resistant composite ceramic material, the preparation method of the high-temperature resistant composite ceramic material comprising the following preparation steps: (1) Mix boron nitride nanosheets and N-methylpyrrolidone in a mass ratio of 1:900, ultrasonically crush at 450 W for 49 h and then centrifuge, take the supernatant and let it stand for sedimentation for 25 h, filter with a 0.05 μm filter membrane, wash 3 times with absolute ethanol, and dry at 75 °C for 25 h to obtain dispersed nano boron nitride; Mix the dispersed nano boron nitride and tetrahydrofuran in a mass ratio of 1:350, ultrasonically vibrate for 55 min, under anhydrous and oxygen-free conditions at -79 °C, add liquid nitrogen 900 times the mass of the dispersed nano boron nitride, stir at 400 r / min for 65 min, add lithium metal particles 1.3 times the mass of the dispersed nano boron nitride, continue to stir for 2 h, introduce oxygen and continue to stir for 7 h, uniformly add deionized water 2 times the mass of the dispersed nano boron nitride within 1 h, continue to stir for 65 min, filter with a 0.05 μm filter membrane, wash 3 times with tetrahydrofuran, chloroform, absolute ethanol and deionized water respectively, and dry at 75 °C for 25 h to obtain hydroxylated nano boron nitride; (2) Mix mullite whiskers, hydroxymethyltriethoxysilane and a 90% ethanol solution in a mass ratio of 1:0.04:35, add acetic acid to adjust the pH to 3, stir at 20 °C and 100 rpm for 7 h and then filter, wash 3 times with absolute ethanol and deionized water respectively, and dry at 75 °C for 25 h to obtain modified mullite whiskers; (3) Mix chloromethyltrichlorosilane, magnesium powder and tetrahydrofuran in a mass ratio of 1:0.4:10, stir in a nitrogen atmosphere at 35 °C and 100 rpm for 2 h, raise the temperature to 55 °C and keep warm for 13 h, lower the temperature to -1 °C, add lithium aluminum hydride 0.02 times the mass of chloromethyltrichlorosilane, raise the temperature to 55 °C and keep warm for 13 h, add a 2 mol / L hydrochloric acid solution to quench, add n-hexane and deionized water, let it stand for stratification and then filter, wash the lower layer 3 times with a 4 mol / L hydrochloric acid solution, dry with anhydrous sodium sulfate and then rotary evaporate to obtain polycarbosilane; Mix polycarbosilane, maleic anhydride, chloroplatinic acid and xylene in a mass ratio of 1:0.04:0.2:15, stir in an argon atmosphere at 75 °C and 300 rpm for 4 h, naturally cool to room temperature and then perform negative pressure rotary evaporation, grind and sieve through a 40-mesh sieve, and keep warm at 95 °C for 4 h to obtain modified polycarbosilane; (4) Mix the modified polycarbosilane, polystyrene pore-forming agent, hydroxylated nano-boron nitride, modified mullite whiskers and absolute ethanol in a mass ratio of 1:0.07:0.02:0.01:1, ultrasonicate for 25 min, ball mill at 250 r / min for 7 h, stir in a water bath at 85 °C until viscous, dry at 75 °C for 13 h, grind and sieve through 35 meshes, load into a mold, heat to 1400 °C at a rate of 1 °C / min in a nitrogen atmosphere, hold at 35 MPa for 65 min, cool to room temperature in the furnace, take out and polish to obtain a high-temperature resistant composite ceramic material. Example 2:

[0025] A preparation method of a high-temperature resistant composite ceramic material, the preparation method of the high-temperature resistant composite ceramic material comprising the following preparation steps: (1) Mix boron nitride nanosheets and N-methylpyrrolidone in a mass ratio of 1:950, ultrasonically crush at 455 W for 48 h and then centrifuge, take the supernatant and let it stand for sedimentation for 24 h, filter with a 0.1 μm filter membrane, wash 4 times with absolute ethanol, and dry at 80 °C for 24 h to obtain dispersed nano-boron nitride; Mix the dispersed nano-boron nitride and tetrahydrofuran in a mass ratio of 1:400, ultrasonicate for 60 min, at -78 °C under anhydrous and anaerobic conditions, add liquid nitrogen 950 times the mass of the dispersed nano-boron nitride, stir at 500 r / min for 60 min, add lithium metal particles 1.4 times the mass of the dispersed nano-boron nitride, continue to stir for 1.5 h, introduce oxygen and continue to stir for 6 h, uniformly add deionized water 3 times the mass of the dispersed nano-boron nitride within 2 h, continue to stir for 60 min, filter with a 0.1 μm filter membrane, wash 4 times with tetrahydrofuran, chloroform, absolute ethanol and deionized water respectively, and dry at 80 °C for 24 h to obtain hydroxylated nano-boron nitride; (2) Mix mullite whiskers, hydroxymethyltriethoxysilane and a 95% ethanol solution in a mass ratio of 1:0.05:40, add acetic acid to adjust the pH to 3.5, stir at 25 °C and 150 rpm for 6 h and then filter, wash 4 times with absolute ethanol and deionized water respectively, and dry at 80 °C for 24 h to obtain modified mullite whiskers; (3) Mix chloromethyltrichlorosilane, magnesium powder, and tetrahydrofuran in a mass ratio of 1:0.5:15, stir at 40 °C and 150 rpm for 1.5 h in a nitrogen atmosphere, raise the temperature to 60 °C and keep it warm for 12 h, cool down to 0 °C, add lithium aluminum hydride in an amount 0.03 times the mass of chloromethyltrichlorosilane, raise the temperature to 60 °C and keep it warm for 12 h, quench with 3 mol / L hydrochloric acid solution, add n-hexane and deionized water, let it stand for layer separation and then filter, wash the lower layer 4 times with 5 mol / L hydrochloric acid solution, dry with anhydrous sodium sulfate and then rotary evaporate to obtain polycarbosilane; Mix polycarbosilane, maleic anhydride, chloroplatinic acid, and xylene in a mass ratio of 1:0.05:0.25:20, stir at 80 °C and 350 rpm for 3 h in an argon atmosphere, naturally cool to room temperature and then perform negative pressure rotary evaporation, grind and sieve through a 50-mesh sieve, and keep it warm at 100 °C for 3 h to obtain modified polycarbosilane; (4) Mix modified polycarbosilane, polystyrene pore-forming agent, hydroxylated nano-boron nitride, modified mullite whiskers, and absolute ethanol in a mass ratio of 1:0.08:0.025:0.02:1.5, ultrasonicate for 30 min, ball mill at 300 r / min for 6 h, stir in a 90 °C water bath until viscous, dry at 80 °C for 12 h, grind and sieve through a 40-mesh sieve, load into a mold, heat up to 1500 °C at 2 °C / min in a nitrogen atmosphere, keep it at 40 MPa for 60 min, cool down to room temperature with the furnace, take out and polish to obtain a high-temperature resistant composite ceramic material. Example 3:

[0026] A preparation method of a high-temperature resistant composite ceramic material, the preparation method of the high-temperature resistant composite ceramic material includes the following preparation steps: (1) Mix boron nitride nanosheets and N-methylpyrrolidone in a mass ratio of 1:1100, ultrasonically crush at 460 W for 47 h and then centrifuge, take the supernatant and let it stand for sedimentation for 23 h, filter with a 0.15 μm filter membrane, wash 5 times with absolute ethanol, dry at 85 °C for 23 h to obtain dispersed nano-boron nitride; Mix dispersed nano-boron nitride and tetrahydrofuran in a mass ratio of 1:450, ultrasonicate for 65 min, at -77 °C under anhydrous and anaerobic conditions, add liquid nitrogen 1000 times the mass of dispersed nano-boron nitride, stir at 600 r / min for 55 min, add metal lithium particles 1.5 times the mass of dispersed nano-boron nitride, continue stirring for 1 h, introduce oxygen and continue stirring for 5 h, uniformly add deionized water 4 times the mass of dispersed nano-boron nitride within 3 h, continue stirring for 55 min, filter with a 0.15 μm filter membrane, wash 5 times with tetrahydrofuran, chloroform, absolute ethanol, and deionized water respectively, dry at 85 °C for 23 h to obtain hydroxylated nano-boron nitride; (2) Mix mullite whiskers, hydroxymethyltriethoxysilane, and an ethanol solution with a mass fraction of 100% at a mass ratio of 1:0.06:45. Add acetic acid to adjust the pH to 4. Stir at 30 °C and 200 rpm for 5 h, then filter. Wash with absolute ethanol and deionized water 5 times each, and dry at 85 °C for 23 h to obtain modified mullite whiskers; (3) Mix chloromethyltrichlorosilane, magnesium powder, and tetrahydrofuran at a mass ratio of 1:0.6:20. Stir at 45 °C and 200 rpm for 1 h in a nitrogen atmosphere, then heat to 65 °C and hold for 11 h. Cool to 1 °C, add lithium aluminum hydride at 0.04 times the mass of chloromethyltrichlorosilane, heat to 65 °C and hold for 11 h. Quench with a 4 mol / L hydrochloric acid solution, add n-hexane and deionized water, let it stand for liquid separation and then filter. Wash the lower layer 5 times with a 6 mol / L hydrochloric acid solution, dry with anhydrous sodium sulfate and then rotary evaporate to obtain polycarbosilane; Mix polycarbosilane, maleic anhydride, chloroplatinic acid, and xylene at a mass ratio of 1:0.06:0.3:25. Stir at 85 °C and 400 rpm for 2 h in an argon atmosphere, naturally cool to room temperature, then perform negative pressure rotary evaporation, grind and sieve through a 60-mesh sieve, and hold at 105 °C for 2 h to obtain modified polycarbosilane; (4) Mix modified polycarbosilane, polystyrene porogen, hydroxylated nano-boron nitride, modified mullite whiskers, and absolute ethanol at a mass ratio of 1:0.09:0.03:0.03:2. Ultrasonic for 35 min, ball mill at 350 r / min for 5 h, stir in a 95 °C water bath until viscous, dry at 85 °C for 11 h, grind and sieve through a 45-mesh sieve, load into a mold, heat to 1600 °C at 3 °C / min in a nitrogen atmosphere, hold at 45 MPa for 55 min, and cool to room temperature with the furnace. Take out and polish to obtain a high-temperature resistant composite ceramic material.

[0027] Comparative Example 1: A preparation method of a high-temperature resistant composite ceramic material, the preparation method of the high-temperature resistant composite ceramic material includes the following preparation steps: (1) Mix boron nitride nanosheets and N-methylpyrrolidone at a mass ratio of 1:950, ultrasonically crush for 48 h at 455 W, then centrifuge. Take the supernatant and let it stand for sedimentation for 24 h, filter with a 0.1 μm filter membrane, wash 4 times with absolute ethanol, and dry at 80 °C for 24 h to obtain dispersed nano boron nitride. Mix the dispersed nano boron nitride and tetrahydrofuran at a mass ratio of 1:400, ultrasonically treat for 60 min. Under anhydrous and anaerobic conditions at -78 °C, add liquid nitrogen 950 times the mass of the dispersed nano boron nitride, stir at 500 r / min for 60 min, add lithium metal particles 1.4 times the mass of the dispersed nano boron nitride, continue stirring for 1.5 h, then introduce oxygen and continue stirring for 6 h. Uniformly add deionized water 3 times the mass of the dispersed nano boron nitride within 2 h, continue stirring for 60 min, filter with a 0.1 μm filter membrane, wash 4 times with tetrahydrofuran, chloroform, absolute ethanol, and deionized water respectively, and dry at 80 °C for 24 h to obtain hydroxylated nano boron nitride; (2) Mix chloromethyltrichlorosilane, magnesium powder, and tetrahydrofuran at a mass ratio of 1:0.5:15, stir at 150 rpm at 40 °C in a nitrogen atmosphere for 1.5 h, raise the temperature to 60 °C and keep it warm for 12 h, cool down to 0 °C, add lithium aluminum hydride 0.03 times the mass of chloromethyltrichlorosilane, raise the temperature to 60 °C and keep it warm for 12 h, quench with 3 mol / L hydrochloric acid solution, add n-hexane and deionized water, let it stand for liquid separation and then filter. Wash the lower layer 4 times with 5 mol / L hydrochloric acid solution, dry with anhydrous sodium sulfate and then rotary evaporate to obtain polycarbosilane. Mix polycarbosilane, maleic anhydride, chloroplatinic acid, and xylene at a mass ratio of 1:0.05:0.25:20, stir at 350 rpm at 80 °C in an argon atmosphere for 3 h, naturally cool to room temperature and then perform negative pressure rotary evaporation, grind and sieve through a 50-mesh sieve, and keep it warm at 100 °C for 3 h to obtain modified polycarbosilane; (3) Mix modified polycarbosilane, polystyrene porogen, hydroxylated nano boron nitride, mullite whiskers, and absolute ethanol at a mass ratio of 1:0.08:0.025:0.02:1.5, ultrasonically treat for 30 min, ball mill at 300 r / min for 6 h, stir in a 90 °C water bath until it becomes viscous, dry at 80 °C for 12 h, grind and sieve through a 40-mesh sieve, load it into a mold, heat up to 1500 °C at 2 °C / min in a nitrogen atmosphere, keep it at 40 MPa for 60 min, cool down to room temperature with the furnace, take it out and polish to obtain a high-temperature resistant composite ceramic material.

[0028] Comparative Example 2: A preparation method of a high-temperature resistant composite ceramic material, the preparation method of the high-temperature resistant composite ceramic material comprising the following preparation steps: (1) Mix boron nitride nanosheets and N-methylpyrrolidone in a mass ratio of 1:950, ultrasonically crush them at 455 W for 48 h, then centrifuge, take the supernatant, let it stand and settle for 24 h, filter it with a 0.1 μm filter membrane, wash it 4 times with absolute ethanol, and dry it at 80 °C for 24 h to obtain dispersed nano boron nitride; Mix the dispersed nano boron nitride and tetrahydrofuran in a mass ratio of 1:400, ultrasonically treat for 60 min, under anhydrous and anaerobic conditions at -78 °C, add liquid nitrogen 950 times the mass of the dispersed nano boron nitride, stir at 500 r / min for 60 min, add lithium metal particles 1.4 times the mass of the dispersed nano boron nitride, continue stirring for 1.5 h, introduce oxygen and continue stirring for 6 h, uniformly add deionized water 3 times the mass of the dispersed nano boron nitride within 2 h, continue stirring for 60 min, filter it with a 0.1 μm filter membrane, wash it 4 times with tetrahydrofuran, chloroform, absolute ethanol and deionized water respectively, and dry it at 80 °C for 24 h to obtain hydroxylated nano boron nitride; (2) Mix mullite whiskers, hydroxymethyltriethoxysilane and a 95% ethanol solution in a mass ratio of 1:0.05:40, add acetic acid to adjust the pH to 3.5, stir at 25 °C and 150 rpm for 6 h, then filter, wash it 4 times with absolute ethanol and deionized water respectively, and dry it at 80 °C for 24 h to obtain modified mullite whiskers; (3) Mix chloromethyltrichlorosilane, magnesium powder and tetrahydrofuran in a mass ratio of 1:0.5:15, stir at 40 °C and 150 rpm for 1.5 h in a nitrogen atmosphere, raise the temperature to 60 °C and keep it warm for 12 h, cool it to 0 °C, add lithium aluminum hydride 0.03 times the mass of chloromethyltrichlorosilane, raise the temperature to 60 °C and keep it warm for 12 h, quench it with 3 mol / L hydrochloric acid solution, add n-hexane and deionized water, let it stand and separate layers, then filter, wash the lower layer 4 times with 5 mol / L hydrochloric acid solution, dry it with anhydrous sodium sulfate and then rotary evaporate to obtain polycarbosilane; (4) Mix polycarbosilane, polystyrene porogen, hydroxylated nano boron nitride, modified mullite whiskers and absolute ethanol in a mass ratio of 1:0.08:0.025:0.02:1.5, ultrasonically treat for 30 min, ball mill at 300 r / min for 6 h, stir in a 90 °C water bath until it becomes viscous, dry it at 80 °C for 12 h, grind and sieve through a 40-mesh screen, load it into a mold, heat it to 1500 °C at a rate of 2 °C / min in a nitrogen atmosphere, keep it at 40 MPa for 60 min, cool it to room temperature with the furnace, take it out and polish to obtain a high-temperature resistant composite ceramic material.

[0029] Comparative Example 3: A preparation method of a high-temperature resistant composite ceramic material, the preparation method of the high-temperature resistant composite ceramic material includes the following preparation steps: (1) Mix boron nitride nanosheets and N-methylpyrrolidone in a mass ratio of 1:950, ultrasonically crush for 48 h at 455 W, then centrifuge. Take the supernatant, let it stand for sedimentation for 24 h, filter with a 0.1 μm filter membrane, wash 4 times with absolute ethanol, and dry at 80 °C for 24 h to obtain dispersed nano boron nitride; Mix the dispersed nano boron nitride and tetrahydrofuran in a mass ratio of 1:400, ultrasonically treat for 60 min. Under anhydrous and anaerobic conditions at -78 °C, add liquid nitrogen 950 times the mass of the dispersed nano boron nitride, stir at 500 r / min for 60 min, add lithium metal particles 1.4 times the mass of the dispersed nano boron nitride, continue stirring for 1.5 h, introduce oxygen and continue stirring for 6 h, uniformly add deionized water 3 times the mass of the dispersed nano boron nitride within 2 h, continue stirring for 60 min, filter with a 0.1 μm filter membrane, wash 4 times with tetrahydrofuran, chloroform, absolute ethanol, and deionized water respectively, and dry at 80 °C for 24 h to obtain hydroxylated nano boron nitride; (2) Mix chloromethyltrichlorosilane, magnesium powder, and tetrahydrofuran in a mass ratio of 1:0.5:15, stir at 150 rpm at 40 °C in a nitrogen atmosphere for 1.5 h, raise the temperature to 60 °C and keep warm for 12 h, cool to 0 °C, add lithium aluminum hydride 0.03 times the mass of chloromethyltrichlorosilane, raise the temperature to 60 °C and keep warm for 12 h, quench with 3 mol / L hydrochloric acid solution, add n-hexane and deionized water, let it stand for layering and then filter. Wash the lower layer 4 times with 5 mol / L hydrochloric acid solution, dry with anhydrous sodium sulfate and then rotary evaporate to obtain polycarbosilane; (4) Mix polycarbosilane, polystyrene porogen, hydroxylated nano boron nitride, mullite whiskers, and absolute ethanol in a mass ratio of 1:0.08:0.025:0.02:1.5, ultrasonically treat for 30 min, ball mill at 300 r / min for 6 h, stir in a 90 °C water bath until viscous, dry at 80 °C for 12 h, grind and sieve through a 40-mesh screen, load into a mold, heat to 1500 °C at a rate of 2 °C / min in a nitrogen atmosphere, keep warm at 40 MPa for 60 min, cool to room temperature with the furnace, take out and polish to obtain a high-temperature resistant composite ceramic material.

[0030] Test Example 1. High-temperature resistance Test method: Weigh 10 mg samples of the high-temperature resistant composite ceramic materials obtained in each example and the comparative example respectively, and use a thermogravimetric analyzer of model TGA / DSC produced by Mettler Toledo AG, Switzerland. Measure the weight loss rate after heating to 1200 °C at a heating rate of 5 °C / min and keeping warm for 1 h in an argon environment.

[0031] 2. Mechanical properties Test method: The high-temperature resistant composite ceramic materials obtained in each example and the comparative examples were tested for compressive strength = failure load / stress area using a HY-0380 universal mechanical tester from Shanghai Hengyi Precision Instrument Co., Ltd. in accordance with GB / T1964.

[0032] 3. Heat preservation Test method: The high-temperature resistant composite ceramic materials obtained in each example and the comparative examples were taken to measure the porosity = (wet weight - dry weight) / (wet weight - floating weight) * 100% using an AuY120 electronic analytical balance produced by Shimadzu Corporation of Japan in accordance with GB / T25995.

[0033] Table 1 below gives the analysis results of the high-temperature resistance, heat preservation, and mechanical properties of the high-temperature resistant composite ceramic materials of Examples 1-3 and Comparative Examples 1-3 of the present invention.

[0034] Table 1 Weight loss rate % Flexural strength MPa Porosity % Example 1 0.63 38.8 45.6 Example 2 0.61 39.4 45.8 Example 3 0.69 38.2 45.5 Comparative Example 1 0.71 39.6 39.3 Comparative Example 2 0.69 41.2 21.7 Comparative Example 3 0.72 40.9 18.4 From the comparison of the experimental data of Examples 1-3 and Comparative Examples 1-3 in Table 1, it can be found that the high-temperature resistant composite ceramic materials prepared by the present invention have good high-temperature resistance, heat preservation, and mechanical properties.

[0035] By comparison, the thermal weight loss rates of Examples 1, 2, and 3 compared with Comparative Examples 1, 2, and 3 illustrate that the high-temperature resistant composite ceramic materials prepared by the present invention have good high-temperature resistance.

[0036] By comparison, Examples 1, 2, and 3 have lower bending strength and higher porosity compared with Comparative Example 1, which shows that mullite whiskers have good grain boundary bonding ability. Using mullite whiskers as the reinforcing phase, when the material is stressed, it plays a "bridging" role, increasing the difficulty of crack propagation and improving the mechanical properties of the high-temperature resistant composite ceramic materials. At the same time, maleic anhydride is grafted onto polycarbosilane by hydrosilylation and undergoes transesterification reaction with modified mullite whiskers. During the calcination process, the ester groups are converted into small molecule gases and overflow, forming a pore structure and improving the heat preservation performance of the high-temperature resistant composite ceramic materials.

[0037] By comparison, Examples 1, 2, and 3 have lower bending strength and higher porosity compared with Comparative Example 2, which shows that maleic anhydride is grafted onto polycarbosilane by hydrosilylation and undergoes transesterification reaction with hydroxylated nano-boron nitride and modified mullite whiskers. The formed ester groups are converted into small molecule gases and overflow during the calcination process, enriching the pore structure and improving the heat preservation performance of the high-temperature resistant composite ceramic materials.

[0038] The specific embodiments described above have further elaborated on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above description is only the specific embodiments of the present invention and is not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation method of a high-temperature resistant composite ceramic material, characterized in that, The high-temperature resistant composite ceramic material is obtained by calcining a mixture of modified polycarbosilane, polystyrene pore-forming agent, hydroxylated nano-boron nitride, and modified mullite whiskers; The modified polycarbosilane is prepared by reacting chloromethyltrichlorosilane through magnesium powder-induced coupling and then reacting with maleic anhydride; The hydroxylated nano-boron nitride is obtained by dispersing boron nitride nanosheets, electro-negativizing them with lithium metal particles, and then reacting with oxygen; The modified mullite whiskers are obtained by reacting mullite whiskers with hydroxymethyltriethoxysilane.

2. The preparation method of a high-temperature resistant composite ceramic material according to claim 1, characterized in that, It includes the following preparation steps: (1) Mix boron nitride nanosheets and N-methylpyrrolidone at a mass ratio of 1:(900 - 1100), ultrasonically crush for 47 - 49 h, then centrifuge, take the supernatant for static sedimentation, filter with a 0.05 - 0.15 μm filter membrane, wash with absolute ethanol 3 - 5 times, dry at 75 - 85 °C for 23 - 25 h to obtain dispersed nano-boron nitride; Mix the dispersed nano-boron nitride and tetrahydrofuran at a mass ratio of 1:(350 - 450), ultrasonically treat for 55 - 65 min, under anhydrous and anaerobic conditions, at -79 - 77 °C, add liquid nitrogen, stir at 400 - 600 r / min for 55 - 65 min, add lithium metal particles 1.3 - 1.5 times the mass of the dispersed nano-boron nitride, continue stirring for 1 - 2 h, introduce oxygen and continue stirring for 5 - 7 h, uniformly add deionized water 2 - 4 times the mass of the dispersed nano-boron nitride within 1 - 3 h, continue stirring for 55 - 65 min, filter with a filter membrane, wash with tetrahydrofuran, chloroform, absolute ethanol, and deionized water 3 - 5 times respectively, dry at 75 - 85 °C for 23 - 25 h to obtain hydroxylated nano-boron nitride; (2) Mix mullite whiskers, hydroxymethyltriethoxysilane, and ethanol solution at a mass ratio of 1:(0.04 - 0.06):(35 - 45), add acetic acid to adjust the pH to 3 - 4, stir at 20 - 30 °C and 100 - 200 rpm for 5 - 7 h, then filter, wash with absolute ethanol and deionized water 3 - 5 times respectively, dry at 75 - 85 °C for 23 - 25 h to obtain modified mullite whiskers; (3) Mix chloromethyltrichlorosilane, magnesium powder, and tetrahydrofuran at a mass ratio of 1:(0.4 - 0.6):(10 - 20), stir at 35 - 45 °C and 100 - 200 rpm for 1 - 2 h in a nitrogen atmosphere, heat up to 55 - 65 °C and keep warm for 11 - 13 h, cool down to -1 - 1 °C, add lithium aluminum hydride in an amount of 0.02 - 0.04 times the mass of chloromethyltrichlorosilane, heat up to 55 - 65 °C and keep warm for 11 - 13 h, quench with hydrochloric acid solution, add n-hexane and deionized water, let it stand for liquid separation and then filter, wash the lower layer with 4 - 6 mol / L hydrochloric acid solution for 3 - 5 times, dry with anhydrous sodium sulfate and then perform rotary evaporation to obtain polycarbosilane; Mix polycarbosilane, maleic anhydride, chloroplatinic acid, and xylene at a mass ratio of 1:(0.04 - 0.06):(0.2 - 0.3):(15 - 25), stir at 75 - 85 °C and 300 - 400 rpm for 2 - 4 h in an argon atmosphere, naturally cool to room temperature and then perform vacuum rotary evaporation, grind and sieve, and keep warm at 95 - 105 °C for 2 - 4 h to obtain modified polycarbosilane; (4) Mix modified polycarbosilane, polystyrene porogen, hydroxylated nano boron nitride, modified mullite whiskers, and absolute ethanol at a mass ratio of 1:(0.07 - 0.09):(0.02 - 0.03):(0.01 - 0.03):(1 - 2), ultrasonicate for 25 - 35 min, ball mill at 250 - 350 r / min for 5 - 7 h, stir in a water bath at 85 - 95 °C until viscous, dry at 75 - 85 °C for 11 - 13 h, grind and sieve through a 35 - 45 mesh sieve, load into a mold, heat up to 1400 - 1600 °C at a rate of 1 - 3 °C / min and keep warm at 35 - 45 MPa for 55 - 65 min in a nitrogen atmosphere, cool down to room temperature with the furnace, take out and polish to obtain a high-temperature resistant composite ceramic material.

3. The preparation method of a high-temperature resistant composite ceramic material according to claim 2, characterized in that, The ultrasonic crushing conditions in step (1) are 450 - 460 W.

4. The preparation method of a high-temperature resistant composite ceramic material according to claim 2, characterized in that, The sedimentation time in step (1) is 23 - 25 h.

5. The preparation method of a high-temperature resistant composite ceramic material according to claim 2, wherein, The amount of liquid nitrogen added in step (1) is 900 - 1000 times the mass of dispersed nano boron nitride.

6. The preparation method of a high-temperature resistant composite ceramic material according to claim 2, characterized in that The filter membrane size in step (1) is 0.05 - 0.15 μm.

7. The preparation method of a high-temperature resistant composite ceramic material according to claim 2, characterized in that The mass fraction of the ethanol solution in step (2) is 90% - 100%.

8. The preparation method of a high-temperature resistant composite ceramic material according to claim 2, characterized in that, The concentration of the hydrochloric acid solution used for quenching in step (3) is 2 - 4 mol / L.

9. The preparation method of a high-temperature resistant composite ceramic material according to claim 2, characterized in that, The particle size of the grinding and sieving in step (3) is 40 - 60 mesh.