Ultra-high temperature ceramic of ZrB2 / SiC / TiB2 and its preparation method

Abstract

The present invention provides a ultra-high temperature ceramic of ZrB2 / SiC / TiB2 and a preparation method thereof, belonging to the field of ultra-high temperature ceramics; the preparation method includes steps of preparing SiC / TiB2 composite particles, modifying SiC / TiB2 composite particles, compounding, preparing ceramic slurry, and forming and calcining; the compounding step is to put the modified SiC / TiB2 composite particles and the modified ZrB2 particles into N-methylpyrrolidone, stir evenly, then add 4,4'-bismaleimide diphenylmethane, and stir at 110-115 °C for 2.8-3.2 h to obtain ZrB2 / SiC / TiB2 particles; the ceramic product prepared by the present invention has high interfacial bonding strength, uniform internal structure, relatively high toughness and strength, good temperature resistance, stable overall performance, and excellent comprehensive performance.

Description

Technical Field

[0001] The present invention belongs to the field of ultra-high temperature ceramics, and in particular relates to an ultra-high temperature ceramic of ZrB2 / SiC / TiB2 and a preparation method thereof. Background Art

[0002] Ultra-high temperature ceramics are a type of ceramic material that can be used for a long time in extremely high temperature environments (usually over 2000°C). This type of ceramic material can still maintain good mechanical properties and antioxidant properties in extremely high temperature environments. With the rapid development of aerospace, high-speed aircraft, and advanced energy, the performance requirements of materials in ultra-high temperature environments are becoming increasingly stringent. The research and development of ultra-high temperature ceramics has become a difficult problem that technicians urgently need to solve. A single ceramic material is often difficult to meet these complex performance requirements, so it has become an inevitable trend to compound ceramic materials with different properties.

[0003] ZrB2-based ceramics are one of the most widely studied ultra-high temperature ceramic systems. They have a melting point of up to 3245°C, high hardness, good electrical conductivity and thermal conductivity, and can maintain good structural stability in ultra-high temperature environments. However, ZrB2 ceramics are easily oxidized to form ZrO2 and B2O3 in a high-temperature oxidizing environment, among which B2O3 is easily volatile at high temperatures, resulting in a sharp decline in material performance. In order to improve this problem, SiC is usually added. SiO2 and B2O3 generated after SiC oxidation form a borosilicate glass phase, which effectively fills the pores on the surface of the material and prevents further diffusion of oxygen, thereby improving the oxidation resistance of ZrB2-based ceramics. However, ZrB2-SiC ceramics have the defects of poor toughness and poor thermal shock resistance. The introduction of TiB2 can further improve the defects of ZrB2-SiC ceramics, improve sintering performance, and enhance the electrical and thermal conductivity of the composite ceramic material, thereby enhancing the stability of the product.

[0004] Therefore, the composite material of ZrB2, SiC and TiB2 can achieve complementary advantages in performance, so that the composite material has the high melting point and good conductivity of ZrB2, the oxidation resistance and thermal shock resistance of SiC, and the high hardness and chemical stability of TiB2, thus meeting the requirements for use in extreme environments such as ultra-high temperature and strong corrosion.

[0005] However, there are differences in the physical properties of ZrB2, SiC, and TiB2 powders. Agglomeration and segregation are likely to occur during the mixing process, making it difficult to achieve uniform dispersion. This will result in non-uniform internal structure and unstable performance of the composite material, reducing the overall performance of the material. Moreover, ZrB2, SiC, and TiB2 all have high melting points and strong covalent bond bindings, making it difficult for atomic diffusion during the sintering process and difficult to achieve densification. During the composite process, chemical reactions are likely to occur at their interfaces, forming brittle phases and weakening the interface bonding strength. In addition, there are certain differences in the thermal expansion coefficients of different materials. During the preparation and use processes, thermal stress will be generated due to temperature changes, which may lead to the generation and expansion of interface cracks, further damaging the interface bonding and affecting the reliability of the material, thus limiting the temperature resistance performance of the material. Summary of the Invention

[0006] To solve the technical problems existing in the prior art, the present invention provides a ultra-high temperature ceramic of ZrB2 / SiC / TiB2 and its preparation method. The ultra-high temperature ceramic has high interface bonding strength, uniform internal structure, relatively high toughness and strength, good temperature resistance, stable overall performance, and excellent comprehensive performance.

[0007] In view of the above technical problems, the present invention adopts the following technical solutions:

[0008] A preparation method of a ultra-high temperature ceramic of ZrB2 / SiC / TiB2, comprising steps of preparing SiC / TiB2 composite particles, modifying SiC / TiB2 composite particles, compounding, preparing ceramic slurry, and forming and calcining, which are specifically as follows:

[0009] 1. Preparing SiC / TiB2 composite particles

[0010] (1) Pretreatment of SiC

[0011] Place SiC particles in a sealed container, introduce 4.8 - 5.2 wt% hydrofluoric acid with a mass 5 - 7 times that of the SiC particles, raise the temperature to 66 - 70 °C, keep warm for 1.8 - 2.2 h, filter out the solid matter, after washing, then put it into a 32 - 37 wt% hydrogen peroxide solution with a mass 5 - 8 times that of the SiC particles, raise the temperature to 73 - 78 °C, keep warm for 3.0 - 4.0 h. After the heat preservation ends, filter, wash, and dry to obtain pretreated SiC particles;

[0012] The particle size of the SiC particles is 150 - 170 nm;

[0013] (2) Coating

[0014] Put the pretreated SiC particles into the coating solution, add polyvinylpyrrolidone, stir at 32 - 37 °C for 35 - 45 min. After stirring, perform homogenization treatment with a homogenization time of 4.0 - 6.0 min and a homogenization pressure of 1.0 - 1.3 MPa. After the homogenization treatment, stir in a constant temperature water bath at 62 - 67 °C and stir at 75 - 85 rpm for 9 - 11 h. After stirring, dry to a constant weight at 82 - 87 °C, and then perform calcination treatment under an argon atmosphere. The calcination temperature is 1480 - 1520 °C, the calcination time is 2.8 - 3.2 h, and the heating rate is 4.8 - 5.2 °C / min. After the calcination, SiC / TiB₂ composite particles are obtained;

[0015] The mass - volume ratio of the pretreated SiC particles, the coating solution, and polyvinylpyrrolidone is 12.5 - 13.4 g:195 - 204 mL:0.6 - 1.0 g;

[0016] The preparation method of the coating solution is as follows: Add tetrabutyl titanate to absolute ethanol, control the addition rate at 0.1 - 0.3 mL / min, and then add glacial acetic acid and disperse it evenly by ultrasonic to obtain Solution 1; Add trimethyl borate to absolute ethanol, control the addition rate at 0.4 - 0.6 mL / min, and disperse it evenly by ultrasonic to obtain Solution 2; Slowly add Solution 2 to Solution 1, control the addition time at 1.8 - 2.2 h, and then add sucrose. After the addition is completed, stir at 170 - 190 rpm for 3.8 - 4.2 h to obtain the coating solution;

[0017] In the Solution 1, the volume ratio of absolute ethanol, tetrabutyl titanate, and glacial acetic acid is 100:18 - 22:2.6 - 3.2;

[0018] In the Solution 2, the volume ratio of absolute ethanol and trimethyl borate is 100:26 - 32;

[0019] The volume - mass ratio of Solution 1, Solution 2, and sucrose is 118 - 122 mL:126 - 134 mL:4.7 - 5.3 g.

[0020] 2. Modification of SiC / TiB₂ composite particles

[0021] Put the SiC / TiB₂ composite particles into toluene solution, stir evenly, add γ - mercaptopropyltrimethoxysilane, raise the temperature to 62 - 67 °C, keep warm and stir for 2.8 - 3.2 h. After stirring, filter, wash, and dry to obtain modified ZrB₂ particles;

[0022] The mass ratio of the SiC / TiB₂ composite particles, toluene solution, and γ - mercaptopropyltrimethoxysilane is 11.4 - 12.5:105 - 116:1.0 - 1.4;

[0023] The mass concentration of the toluene solution is 27 - 32%.

[0024] 3. Composite

[0025] Put the modified SiC / TiB2 composite particles and the modified ZrB2 particles into N-methylpyrrolidone, stir evenly, add 4,4'-bismaleimide diphenylmethane, continue to stir evenly, raise the temperature to 110 - 115 °C at a rate of 0.4 - 0.6 °C / min, keep stirring at 200 - 220 rpm for 2.8 - 3.2 h. After the stirring reaction ends, centrifuge at 3800 - 4200 rpm for 8 - 12 min, discard the supernatant, vacuum-dry the precipitate at 58 - 62 °C for 10.0 - 14.0 h, with the vacuum degree of 0.01 - 0.03 Pa. After the vacuum drying ends, ZrB2 / SiC / TiB2 particles are obtained;

[0026] The mass ratio of the modified SiC / TiB2 composite particles, the modified ZrB2 particles, N-methylpyrrolidone, and 4,4'-bismaleimide diphenylmethane is 7.5 - 8.3:7.8 - 8.2:280 - 320:1.0 - 1.5;

[0027] The preparation method of the modified ZrB2 particles is as follows: Put the ZrB2 particles into deionized water, stir evenly, then carry out ball milling. The ball milling speed is 140 - 160 rpm, and the ball milling time is 37 - 43 min. After the ball milling ends, add 3-aminopropanol, raise the temperature to 62 - 68 °C, and continue ball milling for 1.8 - 2.2 h. After the ball milling ends, after centrifugation, wash the precipitate with deionized water and dry it to constant weight at 82 - 87 °C to obtain the modified ZrB2 particles;

[0028] The particle size of the ZrB2 particles is 130 - 150 nm;

[0029] The mass ratio of the ZrB2 particles, deionized water, and 3-aminopropanol is 14 - 16:100:1.5 - 1.7.

[0030] 4. Preparation of ceramic slurry

[0031] Mix the ZrB2 / SiC / TiB2 particles, polyvinyl alcohol, and deionized water, and carry out ultrasonic dispersion. The ultrasonic power is 200 - 220 W, the ultrasonic frequency is 54 - 56 kHz, and the ultrasonic time is 27 - 32 min to obtain the ceramic slurry;

[0032] The mass ratio of the ZrB2 / SiC / TiB2 particles, polyvinyl alcohol, and deionized water is 48 - 52:1.4 - 1.6:380 - 420.

[0033] 5. Molding and calcination

[0034] The ceramic slurry is centrifuged, and the precipitate is dried to constant weight at 115 - 125 °C, then placed in a high-temperature furnace and sintered under an argon atmosphere. The sintering pressure is 28 - 32 MPa. First, it is heated at a rate of 4.5 - 5.5 °C / min to 780 - 820 °C and held for 28 - 32 min, then heated at a rate of 0.8 - 1.2 °C / min to 1900 - 1920 °C and held for 1.0 - 1.3 h, and then cooled at a rate of 0.8 - 1.2 °C / min to 1100 - 1300 °C. It is cooled with the furnace to room temperature below 1100 - 1300 °C to obtain the ultra-high temperature ceramic of ZrB2 / SiC / TiB2.

[0035] An ultra-high temperature ceramic of ZrB2 / SiC / TiB2 is prepared by the above preparation method.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] 1. The present invention uses ZrB2, SiC, and TiB2 as the ceramic matrix to prepare the ultra-high temperature ceramic. Specifically, surface pretreatment is first carried out on SiC to introduce more active sites on the SiC surface, and then SiC is coated with TiB2. Specifically, tetrabutyl titanate is used as the titanium source and trimethyl borate is used as the boron source. The boron source and the titanium source react to obtain a sol of TiB2 precursor, which forms a TiO2 - B2O3 gel layer on the SiC surface. During the coating process, polyvinylpyrrolidone is added as a dispersant to ensure the uniformity of the coating. Combined with high-temperature treatment under an argon atmosphere, a continuous TiB2 coating layer is formed on the SiC surface, improving the interfacial bonding performance, obtaining SiC / TiB2 composite particles, which can improve the density of the ceramic product, enhance the mechanical properties and oxidation resistance; in the modification step, mercapto silane coupling agent is used to modify the SiC / TiB2 composite particles, making their surface contain mercapto groups; in the composite step, 4,4'-bismaleimide diphenylmethane and modified ZrB2 particles are introduced. The modified ZrB2 particles are obtained by amino modification of ZrB2 particles to introduce amino groups on their surface. 4,4'-bismaleimide diphenylmethane can react with the amino groups and mercapto groups of the modified ZrB2 particles at the same time, promoting the formation of a three-dimensional cross-linked network structure, with good interfacial bonding strength and uniform internal structure, obtaining ZrB2 / SiC / TiB2 particles, constructing a multi-component composite structure, improving the density of the product, and further enhancing the ultra-high temperature performance and comprehensive stability of the ceramic;

[0038] 2. The ultra-high temperature ceramic of ZrB2 / SiC / TiB2 prepared by the present invention has a fracture toughness of 13.4 - 13.7 MPa·m at room temperature 1 / 2 and a flexural strength of 648 - 359 MPa;

[0039] 3. The ultra-high temperature ceramic ZrB2 / SiC / TiB2 prepared by the present invention, at 1800 °C, ablated by oxy-acetylene for 480 s, has a mass ablation rate of 0.207 - 0.214 mg / s and a linear ablation rate of 0.46 - 0.51 μm / s;

[0040] 4. The ultra-high temperature ceramic ZrB2 / SiC / TiB2 prepared by the present invention is kept static in an air environment at 2000 °C for 120 h. After measurement again, its fracture toughness is 12.3 - 12.8 MPa·m 1 / 2 , and its flexural strength is 620 - 636 MPa. Specific Embodiments

[0041] In order to understand the technical features, objectives, and effects of the present invention more clearly, the specific embodiments of the present invention are described below.

[0042] Example 1

[0043] 1. Preparation of SiC / TiB2 composite particles

[0044] (1)Pretreatment of SiC

[0045] Put the SiC particles into a closed container, introduce 6 times the mass of 5.0 wt% hydrofluoric acid, raise the temperature to 68 °C, keep warm for 2.0 h, filter out the solid matter, after washing, then put it into 6 times the mass of 35 wt% hydrogen peroxide solution, raise the temperature to 76 °C, keep warm for 3.5 h. After the heat preservation ends, filter, wash, and dry to obtain pretreated SiC particles;

[0046] The particle size of the SiC particles is 160 nm;

[0047] (2)Coating

[0048] Put 13.0 g of pretreated SiC particles into 200 mL of coating solution, add 0.8 g of polyvinylpyrrolidone, stir at 35 °C for 40 min. After stirring, perform homogenization treatment. The homogenization time is 5.0 min, and the homogenization pressure is 1.2 MPa. After the homogenization treatment, stir in a constant temperature water bath at 65 °C and stir at 80 rpm for 10 h. After stirring, dry to constant weight at 85 °C, and then perform calcination treatment in an argon atmosphere. The calcination temperature is 1500 °C, the calcination time is 3.0 h, and the heating rate is 5.0 °C / min. After the calcination ends, SiC / TiB2 composite particles are obtained;

[0049] The preparation method of the coating liquid is as follows: Add 20 mL of tetrabutyl titanate to 100 mL of absolute ethanol, control the addition rate at 0.2 mL / min, then add 3.0 mL of glacial acetic acid, and disperse evenly by ultrasonic treatment to obtain Solution 1; Add 30 mL of trimethyl borate to 100 mL of absolute ethanol, control the addition rate at 0.5 mL / min, and disperse evenly by ultrasonic treatment to obtain Solution 2; Slowly add 130 mL of Solution 2 to 123 mL of Solution 1, control the addition time at 2.0 h, then add 5.0 g of sucrose. After the addition is completed, stir at 180 rpm for 4.0 h to obtain the coating liquid.

[0050] 2. Modification of SiC / TiB2 composite particles

[0051] Put 12.0 g of SiC / TiB2 composite particles into 110 g of 30 wt% toluene solution. After stirring evenly, add 1.2 g of γ-mercaptopropyltrimethoxysilane, raise the temperature to 64 °C, and keep stirring for 3.0 h. After the stirring ends, filter, wash, and dry to obtain modified ZrB2 particles.

[0052] 3. Composite

[0053] Put 8.0 g of modified SiC / TiB2 composite particles and 8.0 g of modified ZrB2 particles into 300 g of N-methylpyrrolidone. After stirring evenly, add 1.3 g of 4,4'-bismaleimide diphenylmethane, continue to stir evenly, raise the temperature to 114 °C at a rate of 0.5 °C / min, and keep stirring at 210 rpm for 3.0 h. After the stirring reaction ends, centrifuge at 4000 rpm for 10 min, discard the supernatant, and vacuum-dry the precipitate at 60 °C for 12.0 h with a vacuum degree of 0.02 Pa. After the vacuum drying ends, obtain ZrB2 / SiC / TiB2 particles;

[0054] The preparation method of the modified ZrB2 particles is as follows: Put 15 g of ZrB2 particles into 100 g of deionized water, stir evenly, then perform ball milling treatment with a ball milling speed of 150 rpm and a ball milling time of 40 min. After the ball milling ends, add 1.6 g of 3-aminopropanol, raise the temperature to 65 °C, and continue ball milling for 2.0 h. After the ball milling ends, after centrifugation, wash the precipitate with deionized water and dry it to constant weight at 85 °C to obtain modified ZrB2 particles;

[0055] The particle size of the ZrB2 particles is 140 nm.

[0056] 4. Preparation of ceramic slurry

[0057] Mix 50 g of ZrB2 / SiC / TiB2 particles, 1.5 g of polyvinyl alcohol, and 400 g of deionized water, and perform ultrasonic dispersion. The ultrasonic power is 210 W, the ultrasonic frequency is 55 kHz, and the ultrasonic time is 30 min to obtain a ceramic slurry.

[0058] 5. Molding and calcination

[0059] Centrifuge the ceramic slurry, dry the precipitate at 120 °C to constant weight, then place it in a high-temperature furnace and sinter it under an argon atmosphere. The sintering pressure is 30 MPa. First, heat it at a rate of 5.0 °C / min to 800 °C, hold for 30 min, then heat it at a rate of 1.0 °C / min to 1910 °C, hold for 1.2 h, and then cool it at a rate of 1.0 °C / min to 1200 °C. Cool it with the furnace to room temperature below 1200 °C to obtain an ultra-high temperature ceramic of ZrB2 / SiC / TiB2.

[0060] Example 2

[0061] 1. Preparation of SiC / TiB2 composite particles

[0062] (1)SiC pretreatment

[0063] Place the SiC particles in a closed container, introduce 7 times the mass of 5.2 wt% hydrofluoric acid, raise the temperature to 70 °C, hold for 2.2 h, filter out the solid matter, wash it, and then put it into 8 times the mass of 37 wt% hydrogen peroxide solution, raise the temperature to 78 °C, hold for 3.0 h. After the holding is completed, filter, wash, and dry to obtain pretreated SiC particles;

[0064] The particle size of the SiC particles is 170 nm;

[0065] (2)Coating

[0066] Put 13.4 g of pretreated SiC particles into 204 mL of coating solution, add 1.0 g of polyvinylpyrrolidone, stir at 37 °C for 35 min. After stirring, perform homogenization treatment. The homogenization time is 4.0 min, and the homogenization pressure is 1.3 MPa. After the homogenization treatment, stir in a 67 °C constant temperature water bath at 85 rpm for 9 h. After stirring, dry it to constant weight at 87 °C, and then perform calcination treatment under an argon atmosphere. The calcination temperature is 1520 °C, the calcination time is 3.2 h, and the heating rate is 5.2 °C / min. After the calcination is completed, obtain SiC / TiB2 composite particles;

[0067] The preparation method of the coating liquid is as follows: add 22 mL of tetrabutyl titanate to 100 mL of absolute ethanol, control the addition rate at 0.3 mL / min, then add 3.2 mL of glacial acetic acid, and disperse evenly by ultrasonic treatment to obtain Solution 1; add 32 mL of trimethyl borate to 100 mL of absolute ethanol, control the addition rate at 0.6 mL / min, and disperse evenly by ultrasonic treatment to obtain Solution 2; slowly add 134 mL of Solution 2 to 122 mL of Solution 1, control the addition time at 2.2 h, then add 5.3 g of sucrose, and after the addition is completed, stir at 190 rpm for 4.2 h to obtain the coating liquid.

[0068] 2. Modification of SiC / TiB2 composite particles

[0069] Put 12.5 g of SiC / TiB2 composite particles into 116 g of 32 wt% toluene solution, stir evenly, add 1.4 g of γ-mercaptopropyltrimethoxysilane, raise the temperature to 67 °C, keep stirring for 3.2 h, after the stirring ends, filter, wash and dry to obtain modified ZrB2 particles.

[0070] 3. Composite

[0071] Put 8.3 g of modified SiC / TiB2 composite particles and 7.8 g of modified ZrB2 particles into 320 g of N-methylpyrrolidone, stir evenly, add 1.5 g of 4,4'-bismaleimide diphenylmethane, continue to stir evenly, raise the temperature to 115 °C at a rate of 0.6 °C / min, keep stirring at 220 rpm for 2.8 h, after the stirring reaction ends, centrifuge at 4200 rpm for 8 min, discard the supernatant, vacuum-dry the precipitate at 62 °C for 10.0 h, with the vacuum degree of 0.03 Pa, after the vacuum drying ends, obtain ZrB2 / SiC / TiB2 particles;

[0072] The preparation method of the modified ZrB2 particles is as follows: put 16 g of ZrB2 particles into 100 g of deionized water, stir evenly, then carry out ball milling treatment, with the ball milling speed of 160 rpm and the ball milling time of 43 min, after the ball milling ends, add 1.7 g of 3-aminopropanol, raise the temperature to 68 °C, continue ball milling for 1.8 h, after the ball milling ends, after centrifugation, wash the precipitate with deionized water, and dry to constant weight at 87 °C to obtain modified ZrB2 particles;

[0073] The particle size of the ZrB2 particles is 150 nm.

[0074] 4. Preparation of ceramic slurry

[0075] Mix 52 g of ZrB2 / SiC / TiB2 particles, 1.6 g of polyvinyl alcohol, and 420 g of deionized water, and perform ultrasonic dispersion. The ultrasonic power is 220 W, the ultrasonic frequency is 56 kHz, and the ultrasonic time is 32 min to obtain a ceramic slurry.

[0076] 5. Molding and calcination

[0077] Centrifuge the ceramic slurry, dry the precipitate at 125 °C to constant weight, then place it in a high-temperature furnace and sinter it under an argon atmosphere. The sintering pressure is 32 MPa. First, heat it at a rate of 5.5 °C / min to 820 °C, hold for 32 min, then heat it at a rate of 1.2 °C / min to 1920 °C, hold for 1.0 h, and then cool it at a rate of 1.2 °C / min to 1300 °C. Cool it with the furnace to room temperature below 1300 °C to obtain a ultra-high temperature ceramic of ZrB2 / SiC / TiB2.

[0078] Example 3

[0079] 1. Preparation of SiC / TiB2 composite particles

[0080] (1)SiC pretreatment

[0081] Place the SiC particles in a closed container, introduce 5 times the mass of 4.8 wt% hydrofluoric acid, raise the temperature to 66 °C, hold for 1.8 h, filter out the solid matter, wash it, and then put it into 5 times the mass of 32 wt% hydrogen peroxide solution, raise the temperature to 73 °C, hold for 4.0 h. After the holding is completed, filter, wash, and dry to obtain pretreated SiC particles;

[0082] The particle size of the SiC particles is 150 nm;

[0083] (2)Coating

[0084] Put 12.5 g of pretreated SiC particles into 195 mL of coating solution, add 0.6 g of polyvinylpyrrolidone, stir at 32 °C for 45 min. After stirring, perform homogenization treatment. The homogenization time is 6.0 min, and the homogenization pressure is 1.0 MPa. After the homogenization treatment, stir in a 62 °C constant temperature water bath at 75 rpm for 11 h. After stirring, dry to constant weight at 82 °C, and then perform calcination treatment under an argon atmosphere. The calcination temperature is 1480 °C, the calcination time is 2.8 h, and the heating rate is 4.8 °C / min. After the calcination is completed, obtain SiC / TiB2 composite particles;

[0085] The preparation method of the coating liquid is as follows: Add 18 mL of tetrabutyl titanate to 100 mL of absolute ethanol, control the addition rate at 0.1 mL / min, then add 2.6 mL of glacial acetic acid, and disperse evenly by ultrasonic treatment to obtain Solution 1; Add 28 mL of trimethyl borate to 100 mL of absolute ethanol, control the addition rate at 0.4 mL / min, and disperse evenly by ultrasonic treatment to obtain Solution 2; Slowly add 126 mL of Solution 2 to 118 mL of Solution 1, control the addition time at 1.8 h, then add 4.7 g of sucrose. After the addition is completed, stir at 170 rpm for 3.8 h to obtain the coating liquid.

[0086] 2. Modification of SiC / TiB2 composite particles

[0087] Put 11.4 g of SiC / TiB2 composite particles into 105 g of 27 wt% toluene solution. After stirring evenly, add 1.0 g of γ-mercaptopropyltrimethoxysilane, raise the temperature to 62 °C, and keep stirring for 2.8 h. After the stirring ends, filter, wash, and dry to obtain modified ZrB2 particles.

[0088] 3. Composite

[0089] Put 7.5 g of modified SiC / TiB2 composite particles and 8.2 g of modified ZrB2 particles into 280 g of N-methylpyrrolidone. After stirring evenly, add 1.0 g of 4,4'-bismaleimide diphenylmethane, continue to stir evenly, raise the temperature to 110 °C at a rate of 0.4 °C / min, and keep stirring at 200 rpm for 3.2 h. After the stirring reaction ends, centrifuge at 3800 rpm for 12 min, discard the supernatant, and vacuum-dry the precipitate at 58 °C for 14.0 h with a vacuum degree of 0.01 Pa. After the vacuum drying ends, obtain ZrB2 / SiC / TiB2 particles;

[0090] The preparation method of the modified ZrB2 particles is as follows: Put 14 g of ZrB2 particles into 100 g of deionized water, stir evenly, then carry out ball milling treatment with a ball milling speed of 140 rpm and a ball milling time of 37 min. After the ball milling ends, add 1.5 g of 3-aminopropanol, raise the temperature to 62 °C, and continue ball milling for 2.2 h. After the ball milling ends, after centrifugation, wash the precipitate with deionized water and dry it to constant weight at 82 °C to obtain modified ZrB2 particles;

[0091] The particle size of the ZrB2 particles is 130 nm.

[0092] 4. Preparation of ceramic slurry

[0093] Mix 48 g of ZrB2 / SiC / TiB2 particles, 1.4 g of polyvinyl alcohol, and 380 g of deionized water, and perform ultrasonic dispersion. The ultrasonic power is 200 W, the ultrasonic frequency is 54 kHz, and the ultrasonic time is 27 min to obtain a ceramic slurry.

[0094] 5. Molding and calcination

[0095] Centrifuge the ceramic slurry, dry the precipitate at 115 °C to constant weight, then put it into a high-temperature furnace and sinter it under an argon atmosphere. The sintering pressure is 28 MPa. First, heat it at a rate of 4.5 °C / min to 780 °C and hold for 28 min, then heat it at a rate of 0.8 °C / min to 1900 °C and hold for 1.3 h, and then cool it at a rate of 0.8 °C / min to 1100 °C. Cool it with the furnace to room temperature below 1100 °C to obtain an ultra-high temperature ceramic of ZrB2 / SiC / TiB2.

[0096] Comparative example 1

[0097] 1. Preparation of SiC / TiB2 composite particles

[0098] (1)SiC pretreatment

[0099] It is exactly the same as that in Example 1;

[0100] (2)Coating

[0101] The preparation method of the coating liquid is as follows: Add 6.0 g of titanium boride particles to 200 mL of absolute ethanol and stir evenly to obtain a coating liquid; the particle size of the titanium boride particles is 110 nm; the remaining operations are exactly the same.

[0102] The steps of modifying, compounding, preparing the ceramic slurry, and molding and calcining the SiC / TiB2 composite particles are exactly the same as those in Example 1.

[0103] Comparative example 2

[0104] 1. Preparation of SiC / TiB2 composite particles

[0105] It is exactly the same as that in Example 1;

[0106] 2. Modification of SiC / TiB2 composite particles

[0107] It is exactly the same as that in Example 1;

[0108] 3. Compounding

[0109] 8.0 g of modified SiC / TiB2 composite particles and ZrB2 particles were put into 300 g of N-methylpyrrolidone. After stirring evenly, the supernatant was discarded, and the precipitate was vacuum dried at 60 °C for 12.0 h with a vacuum degree of 0.02 Pa. After the vacuum drying was completed, ZrB2 / SiC / TiB2 particles were obtained.

[0110] The particle size of the ZrB2 particles is 140 nm.

[0111] The steps of preparing the ceramic slurry and forming and calcining are exactly the same as those in Example 1.

[0112] Performance test

[0113] The ultra-high temperature ceramic products prepared in Examples 1-3 and Comparative Examples 1-2 were subjected to performance tests, and the test results are as follows:

[0114]

[0115] In the present invention, ZrB2, SiC, and TiB2 are used as ceramic matrices to prepare ultra-high temperature ceramics. Specifically, surface pretreatment is first performed on SiC to introduce more active sites on the surface of SiC, and then SiC is coated with TiB2. Specifically, tetrabutyl titanate is used as the titanium source and trimethyl borate is used as the boron source. The boron source and the titanium source react to obtain a sol of TiB2 precursor, which forms a TiO2-B2O3 gel layer on the surface of SiC. During the coating process, polyvinylpyrrolidone is added as a dispersant to ensure the uniformity of the coating. Combined with high-temperature treatment in an argon atmosphere, a continuous TiB2 coating layer is formed on the surface of SiC, improving the interfacial bonding performance, and SiC / TiB2 composite particles are obtained, which can improve the density of the ceramic product and enhance the mechanical properties and oxidation resistance; in the modification step, mercapto silane coupling agent is used to modify the SiC / TiB2 composite particles, so that their surfaces contain mercapto groups; in the composite step, 4,4'-bismaleimide diphenylmethane and modified ZrB2 particles are introduced. The modified ZrB2 particles are obtained by amino modification of ZrB2 particles, so that amino groups are introduced on their surfaces. 4,4'-bismaleimide diphenylmethane can react with the amino groups and mercapto groups of the modified ZrB2 particles at the same time, promoting the formation of a three-dimensional cross-linked network structure with good interfacial bonding strength and a uniform internal structure. ZrB2 / SiC / TiB2 particles are obtained, constructing a multi-component composite structure, improving the density of the product, and further enhancing the ultra-high temperature performance and comprehensive stability of the ceramic.

[0116] Comparative Example 1 is to directly mix titanium boride with pretreated silicon carbide. Its interfacial compatibility with silicon carbide particles is poor and the dispersibility is not good, resulting in a weak bonding force between the two, which will affect the homogeneity of the ceramic slurry, and ultimately affect the internal uniformity of the ceramic product, making its mechanical properties and toughness poor, and the temperature resistance performance is not good, and the comprehensive performance is unstable; in Comparative Example 2, in the compounding step, the modified SiC / TiB2 composite particles and ZrB2 particles are directly mixed, which will make the mixing degree of the modified SiC / TiB2 composite particles and ZrB2 particles uneven, and the interfacial bonding property is not good, and 4,4'-bismaleimide diphenylmethane is not introduced for cross-linking reaction, and thus a stable cross-linked network structure cannot be formed, ultimately affecting the stability performance and temperature resistance performance of the ceramic product.

[0117] Unless otherwise specified, the percentages used in the present invention are all mass percentages.

[0118] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A preparation method of a ultra-high temperature ceramic of ZrB2 / SiC / TiB2, characterized in that It includes steps of preparing SiC / TiB2 composite particles, modifying SiC / TiB2 composite particles, compounding, preparing ceramic slurry, and forming and calcining; The step of preparing SiC / TiB2 composite particles includes SiC pretreatment and coating steps; The coating step is to put pretreated SiC particles into a coating solution, add polyvinylpyrrolidone, stir, then perform homogenization treatment, react in a constant temperature water bath at 62 - 67 °C, dry, and then obtain SiC / TiB2 composite particles through calcination; The preparation method of the coating solution is to add tetrabutyl titanate and glacial acetic acid to absolute ethanol to obtain Solution 1; add trimethyl borate to absolute ethanol to obtain Solution 2; add Solution 2 to Solution 1, control the addition time to be 1.8 - 2.2 h, and then add sucrose to obtain the coating solution; The step of modifying SiC / TiB2 composite particles is to put SiC / TiB2 composite particles into a toluene solution, stir evenly, add γ-mercaptopropyltrimethoxysilane, raise the temperature to 62 - 67 °C, keep stirring for 2.8 - 3.2 h, after stirring ends, filter, wash, and dry to obtain modified SiC / TiB2 composite particles; The compounding step is to put modified SiC / TiB2 composite particles and modified ZrB2 particles into N-methylpyrrolidone, stir evenly, add 4,4'-bismaleimide diphenylmethane, and stir at 110 - 115 °C for 2.8 - 3.2 h to obtain ZrB2 / SiC / TiB2 particles; The preparation method of the modified ZrB2 particles is to put ZrB2 particles into deionized water, stir evenly, perform ball milling, the ball milling speed is 140 - 160 rpm, the ball milling time is 37 - 43 min, after ball milling ends, add 3-aminopropanol, raise the temperature to 62 - 68 °C, continue ball milling for 1.8 - 2.2 h, after ball milling ends, after centrifugation, wash the precipitate with deionized water, and dry to constant weight to obtain modified ZrB2 particles.

2. The preparation method of a ultra-high temperature ceramic of ZrB2 / SiC / TiB2 according to claim 1, characterized in that The SiC particle pretreatment step is to put SiC particles into a closed container, introduce 5 - 7 times the mass of 4.8 - 5.2 wt% hydrofluoric acid, raise the temperature to 66 - 70 °C, keep warm for 1.8 - 2.2 h, filter out the solid matter, after washing, then put it into 5 - 8 times the mass of 32 - 37 wt% hydrogen peroxide solution, raise the temperature to 73 - 78 °C, keep warm for 3.0 - 4.0 h, after the heat preservation ends, filter, wash, and dry to obtain pretreated SiC particles; The particle size of the SiC particles is 150 - 170 nm.

3. The preparation method of a ultra-high temperature ceramic of ZrB2 / SiC / TiB2 according to claim 1, characterized in that The coating step is as follows: Put the pretreated SiC particles into the coating solution, add polyvinylpyrrolidone, stir at 32 - 37 °C for 35 - 45 min. After stirring, carry out homogenization treatment. The homogenization time is 4.0 - 6.0 min, and the homogenization pressure is 1.0 - 1.3 MPa. After the homogenization treatment, stir in a constant temperature water bath at 62 - 67 °C, stir at 75 - 85 rpm for 9 - 11 h. After stirring, dry to constant weight at 82 - 87 °C, and then carry out calcination treatment under an argon atmosphere. The calcination temperature is 1480 - 1520 °C, the calcination time is 2.8 - 3.2 h, and the heating rate is 4.8 - 5.2 °C / min. After the calcination, SiC / TiB2 composite particles are obtained; The mass - volume ratio of the pretreated SiC particles, the coating solution, and polyvinylpyrrolidone is 12.5 - 13.4 g:195 - 204 mL:0.6 - 1.0 g.

4. The preparation method of a ultra - high temperature ceramic of ZrB2 / SiC / TiB2 according to claim 1, characterized in that The preparation method of the coating solution is as follows: Add tetrabutyl titanate to anhydrous ethanol, control the addition rate at 0.1 - 0.3 mL / min, and then add glacial acetic acid, and disperse evenly by ultrasonic to obtain Solution 1; Add trimethyl borate to anhydrous ethanol, control the addition rate at 0.4 - 0.6 mL / min, and disperse evenly by ultrasonic to obtain Solution 2; Slowly add Solution 2 to Solution 1, control the addition time at 1.8 - 2.2 h, and then add sucrose. After adding, stir at 170 - 190 rpm for 3.8 - 4.2 h to obtain the coating solution; In the Solution 1, the volume ratio of anhydrous ethanol, tetrabutyl titanate, and glacial acetic acid is 100:18 - 22:2.6 - 3.2; In the Solution 2, the volume ratio of anhydrous ethanol and trimethyl borate is 100:26 - 32; The volume - mass ratio of Solution 1, Solution 2, and sucrose is 118 - 122 mL:126 - 134 mL:4.7 - 5.3 g.

5. The preparation method of a ultra - high temperature ceramic of ZrB2 / SiC / TiB2 according to claim 1, characterized in that In the modification step of the SiC / TiB2 composite particles, the mass ratio of the SiC / TiB2 composite particles, toluene solution, and γ - mercaptopropyltrimethoxysilane is 11.4 - 12.5:105 - 116:1.0 - 1.4; The mass concentration of the toluene solution is 27 - 32%.

6. The preparation method of a ultra - high temperature ceramic of ZrB2 / SiC / TiB2 according to claim 1, characterized in that The composite step is as follows: Put the modified SiC / TiB2 composite particles and the modified ZrB2 particles into N-methylpyrrolidone. After stirring evenly, add 4,4'-bismaleimide diphenylmethane, and continue to stir evenly. Raise the temperature to 110-115°C at a rate of 0.4-0.6°C / min, and keep stirring at 200-220 rpm for 2.8-3.2 h. After the stirring reaction ends, centrifuge and discard the supernatant, and then conduct vacuum drying to obtain ZrB2 / SiC / TiB2 particles; The mass ratio of the modified SiC / TiB2 composite particles, the modified ZrB2 particles, N-methylpyrrolidone, and 4,4'-bismaleimide diphenylmethane is 7.5-8.3:7.8-8.2:280-320:1.0-1.

5.

7. According to the preparation method of a ZrB2 / SiC / TiB2 ultra-high temperature ceramic as described in claim 6, characterized in that, In the preparation method of the modified ZrB2 particles, the particle size of the ZrB2 particles is 130-150 nm; The mass ratio of the ZrB2 particles, deionized water, and 3-aminopropanol is 14-16:100:1.5-1.

7.

8. According to the preparation method of a ZrB2 / SiC / TiB2 ultra-high temperature ceramic as described in claim 1, characterized in that, The step of preparing the ceramic slurry is as follows: Mix the ZrB2 / SiC / TiB2 particles, polyvinyl alcohol, and deionized water, and conduct ultrasonic dispersion. The ultrasonic power is 200-220 W, the ultrasonic frequency is 54-56 kHz, and the ultrasonic time is 27-32 min to obtain the ceramic slurry; The mass ratio of the ZrB2 / SiC / TiB2 particles, polyvinyl alcohol, and deionized water is 48-52:1.4-1.6:380-420.

9. According to the preparation method of a ZrB2 / SiC / TiB2 ultra-high temperature ceramic as described in claim 1, characterized in that, The forming and calcining step is as follows: Centrifuge the ceramic slurry, dry the precipitate to constant weight at 115-125°C, then put it into a high-temperature furnace, and conduct sintering under an argon atmosphere. The sintering pressure is 28-32 MPa. First, raise the temperature to 780-820°C at a rate of 4.5-5.5°C / min, keep it warm for 28-32 min, then raise the temperature to 1900-1920°C at a rate of 0.8-1.2°C / min, keep it warm for 1.0-1.3 h, and then lower the temperature to 1100-1300°C at a rate of 0.8-1.2°C / min. Cool it to room temperature with the furnace below 1100-1300°C to obtain the ZrB2 / SiC / TiB2 ultra-high temperature ceramic.

10. A ultra-high temperature ceramic of ZrB2 / SiC / TiB2, characterized in that, Prepared by the preparation method described in any one of claims 1-9.

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