A silicon carbide bulletproof ceramic and its preparation method

Abstract

This invention provides a silicon carbide bulletproof ceramic and its preparation method, comprising the following raw materials in parts by weight: 80 parts α-SiC powder, 20-30 parts boron carbide powder, 0.8-1 parts first dispersant, 0.5-0.8 parts second dispersant, 10-18 parts organic additives, and 0.5-2 parts sintering aids. The ceramic is produced through powder dispersion, batching, water-based spray granulation, dry pressing, secondary densification pressing, shrinkage sintering, and pressureless sintering processes. By employing secondary densification pressing and shrinkage sintering processes, the ceramic green body is densified multiple times, improving the tight bonding between particles and fully utilizing the reinforcing phase boron carbide. This enhances the toughness and strength properties of the silicon carbide ceramic. Experiments show that compared to traditional processes, the bulletproof ceramic of this method exhibits an 11.63% increase in flexural strength, an 8.35% increase in Vickers hardness, and a 15.9% increase in fracture toughness, resulting in a significant improvement in overall mechanical properties.

Description

Technical Field

[0001] This invention relates to the field of bulletproof ceramics technology, and in particular to a silicon carbide bulletproof ceramic and its preparation method. Background Technology

[0002] With the rapid development of military technology and the continuous research and application of highly lethal weapons, the protective equipment for combat personnel and their transport and weapons must be constantly upgraded and rapidly developed to better protect themselves and improve combat effectiveness. Furthermore, the rapid development of anti-armor weapon technology has placed higher demands on the performance of armor protection materials to enhance the battlefield survivability of weaponry, thus promoting the further development of ballistic materials. The development of high-strength, high-hardness, high-toughness, and low-density protective materials is essential to achieving the lightweight and efficient operational requirements of modern warfare. Ballistic materials have evolved from traditional metallic materials (steel, aluminum) to advanced ceramic materials and composite materials (polymer-based, metal-based, ceramic-based), consistently moving towards lightweight and high-efficiency. Currently, alumina, silicon carbide, and boron carbide are the most widely used ballistic ceramics, with silicon carbide / boron carbide composite ceramics being the most commercially available. In the prior art, Chinese invention patent application number CN202110255600.2 discloses a pressureless sintered silicon carbide bulletproof ceramic and its preparation method. By weight, it comprises the following components: 96.5-98.5 parts of carbide A, 1.1-1.8 parts of carbide B, 0.1-1 parts of boride, 12-18 parts of resin, 1-3 parts of oxide, and 0.15-0.45 parts of dispersant. The particle size of carbide A is 50-500 nm, and carbide A is silicon carbide. Carbide B is selected from one or more of boron carbide, tungsten carbide, chromium carbide, and molybdenum carbide. The bulletproof ceramic is prepared through a process of batching, granulation, pressing, drying, and vacuum sintering, with a density of 3.12-3.16 g / m³. 3， The flexural strength is 245-395 MPa, and the Vickers hardness is 2300-2555 HV. Experimental data shows that the mechanical properties of the bulletproof ceramic produced using this method are relatively low. Summary of the Invention

[0003] Based on this, the present invention provides a silicon carbide composite bulletproof material and its preparation method to solve the technical problem of low mechanical properties of bulletproof ceramics in the prior art.

[0004] The technical solution of the present invention to solve the above-mentioned technical problems is as follows:

[0005] A method for preparing silicon carbide bulletproof ceramic includes the following steps:

[0006] S1. Prepare the raw materials according to the following parts by weight: 80 parts of α-SiC powder, 20-30 parts of boron carbide powder, 0.8-1 parts of the first dispersant, 0.5-0.8 parts of the second dispersant, 10-18 parts of organic additives, and 0.5-2 parts of sintering aids;

[0007] S2. Powder dispersion: α-SiC powder and the first dispersant are dispersed in deionized water to obtain an α-SiC dispersion solution; boron carbide powder and the second dispersant are dispersed in deionized water to obtain a boron carbide dispersion solution.

[0008] S3. Ingredient preparation: Mix and stir the α-SiC dispersion solution and the boron carbide dispersion solution, add organic additives and ball mill for 1-2 hours, then add sintering aids and ball mill to obtain α-SiC / B4C mixed slurry;

[0009] S4. Water-based spray granulation: spray granulation of α-SiC / B4C mixed slurry into granulated powder pellets;

[0010] S5. First dry pressing molding, pressing granulated powder pellets into α-SiC / B4C multiphase ceramic green body;

[0011] S6. Shrinkage sintering: The α-SiC / B4C multiphase ceramic green body, which was first dry-pressed, is heated to a predetermined process temperature and vacuum sintered for a predetermined process time.

[0012] S7. Secondary densification pressing: The α-SiC / B4C multiphase ceramic green body after shrinkage sintering is subjected to secondary densification pressing at 80-100MPa.

[0013] S8. Pressureless sintering: Pressureless sintering of α-SiC / B4C multiphase ceramic green body to obtain α-SiC / B4C composite bulletproof ceramic;

[0014] Among them, the α-SiC powder D 50 ≤0.8μm, purity ≥99.5%;

[0015] The boron carbide powder D 50 ≤0.8μm, purity ≥98.5%.

[0016] Preferably, in the above-mentioned method for preparing silicon carbide bulletproof ceramics, the first dispersant is ammonium polyacrylate or sodium lignosulfonate.

[0017] Preferably, in the above-mentioned method for preparing silicon carbide bulletproof ceramics, the second dispersant is polyoxypropylene or ethylene oxide.

[0018] Preferably, in the above-mentioned method for preparing silicon carbide bulletproof ceramics, the organic additive is a mixture of polyvinyl alcohol and polyethylene glycol, wherein the mass ratio of polyvinyl alcohol to polyethylene glycol is (5-8):(5-10).

[0019] Preferably, in the above-mentioned method for preparing silicon carbide bulletproof ceramics, the sintering aid is a mixture of n-butanol and stearic acid, wherein the mass ratio of n-butanol to stearic acid is 1:3.

[0020] Preferably, in the above-mentioned method for preparing silicon carbide bulletproof ceramics, the predetermined process temperature is 300℃±10℃.

[0021] Preferably, in the preparation method of the above-mentioned silicon carbide composite bulletproof material, the predetermined process time is 40-60 minutes.

[0022] Preferably, in the above-mentioned method for preparing silicon carbide bulletproof ceramics, the raw materials further include 8-15 parts of β-SiC powder, wherein the β-SiC powder D 50 ≤100nm, purity ≥99.9%.

[0023] A silicon carbide bulletproof ceramic is prepared by the above-mentioned method for preparing silicon carbide bulletproof ceramic.

[0024] The technical solution adopted in this application can achieve the following beneficial effects:

[0025] This invention discloses a silicon carbide bulletproof ceramic and its preparation method. α-SiC is used as the matrix, and boron carbide is used as the reinforcing phase to enhance the hardness of the silicon carbide ceramic. However, due to the strong bonding of boron carbide, densification sintering is not easily achieved. Therefore, this method employs a secondary densification pressing and shrinkage sintering process to densify the ceramic green body multiple times, improving the tight bonding between particles and fully utilizing the role of the reinforcing phase boron carbide to enhance the toughness and strength of the silicon carbide ceramic. Experiments show that compared to traditional processes, the bulletproof ceramic prepared using this method exhibits an 11.63% increase in flexural strength, an 8.35% increase in Vickers hardness, and a 15.9% increase in fracture toughness, resulting in a significant improvement in overall mechanical properties. Attached Figure Description

[0026] Figure 1 A process flow diagram for the preparation of silicon carbide bulletproof ceramics. Detailed Implementation

[0027] To facilitate understanding of this application, a more comprehensive description will be provided below with reference to relevant experimental examples. Preferred embodiments of this application are shown in the experimental examples. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. In one embodiment of this invention, a method for preparing silicon carbide bulletproof ceramic includes the following steps:

[0029] S1. Prepare the raw materials according to the following parts by weight: 80 parts of α-SiC powder, 20-30 parts of boron carbide powder, 0.8-1 parts of the first dispersant, 0.5-0.8 parts of the second dispersant, 10-18 parts of organic additives, and 0.5-2 parts of sintering aids.

[0030] In one embodiment, the second dispersant is polyoxypropylene or ethylene oxide.

[0031] In one embodiment, the organic additive is a mixture of polyvinyl alcohol and polyethylene glycol, wherein the mass ratio of polyvinyl alcohol to polyethylene glycol is (5-8):(5-10).

[0032] In one embodiment, the sintering aid is a mixture of n-butanol and stearic acid, wherein the mass ratio of n-butanol to stearic acid is 1:3.

[0033] S2. Powder dispersion: α-SiC powder and the first dispersant are dispersed in deionized water to obtain an α-SiC dispersion solution; boron carbide powder and the second dispersant are dispersed in deionized water to obtain a boron carbide dispersion solution.

[0034] For example: Add 0.8-1 parts of polyurethane polyacrylate or sodium lignosulfonate to 1000g of deionized water and stir for 30min, then add 80 parts of α-SiC powder and stir at 40℃ for 1-2 hours to obtain an α-SiC dispersion solution. Add 0.5-0.8 parts of polyoxypropylene or ethylene oxide dispersant to 500g of deionized water and stir for 30-40min, then add 20-30 parts of boron carbide (B4C) powder and ultrasonically stir for 1-2 hours to obtain a uniform, stable, and highly dispersible B4C dispersion solution.

[0035] S3. Ingredient preparation: Mix and stir the α-SiC dispersion solution and the boron carbide dispersion solution, add organic additives and ball mill for 1-2 hours, then add sintering aids and ball mill to obtain α-SiC / B4C mixed slurry.

[0036] For example: The above α-SiC dispersion solution and B4C dispersion solution are mixed and stirred at room temperature for 30-60 minutes. Then, 5-8 parts of polyvinyl alcohol (PVA) and 5-10 parts of polyethylene glycol (PEG) are added, and the mixture is ball-milled in a ball mill at 1008 r / min for 1-2 hours to ensure the binder is uniformly coated on the surface of the powder particles, providing sufficient carbon source for the sintering process. Next, 0.5 parts of n-butanol and 1.5 parts of stearic acid are added to the ball mill, and the mixture is ball-milled for 1 hour to obtain an α-SiC / B4C slurry. n-Butanol is an antifoaming agent. During the stirring process, air enters the slurry, generating a large amount of foam, which leads to hollow granules with poor sphericity, further affecting the performance of the subsequent composite bulletproof ceramic. The role of n-butanol is to eliminate the foam generated during the stirring process. Stearic acid is a lubricant. By wetting the surface of the powder particles, it reduces the friction between powder particles and between the powder and the mold, improving powder flowability and the density of the green body.

[0037] S4. Water-based spray granulation: The α-SiC / B4C mixture slurry is spray-granulated into granulated powder balls.

[0038] In some specific embodiments, a spray granulation tower is preferentially used to spray granulate the α-SiC / B4C mixture slurry. The spray granulation parameters are set as follows: inlet temperature 210-240℃, outlet temperature 90-110℃, and atomizing disc rotation speed 10-13 Hz. Z It is made into granulated powder balls of 70-150μm.

[0039] S5. First dry pressing molding: granulated powder pellets are pressed into α-SiC / B4C multiphase ceramic blanks.

[0040] Specifically, the granulated powder pellets are pressed into α-SiC / B4C multiphase ceramic green bodies of a certain size using a hydraulic press with a pressure of 9MPa. This is the first densification of the powder particles, which allows the powder particles to be reasonably distributed and tightly bonded.

[0041] S6. Shrinkage sintering: The α-SiC / B4C multiphase ceramic green body, which was first dry-pressed, is heated to a predetermined process temperature and vacuum sintered for a predetermined process time.

[0042] Furthermore, the predetermined process temperature is 300℃±10℃.

[0043] Furthermore, the predetermined process time is 40-60 minutes.

[0044] For example, the first dry-pressed multiphase ceramic green body is placed in a vacuum sintering furnace, and the furnace is heated to 300℃±10℃, where it is sintered for 40-60 minutes. Shrink sintering of the multiphase ceramic green body achieves a second, tighter bonding of powder particles through high-temperature shrinkage and the removal of organic matter.

[0045] S7. Secondary densification pressing: The α-SiC / B4C multiphase ceramic green body after shrinkage sintering is subjected to secondary densification pressing at 80-100 MPa. Specifically, an isostatic press is used to re-extrude the sintered and shrunk multiphase ceramic green body at a pressure of 80-100 MPa. This removes the pores generated inside the green body during the sintering shrinkage process, resulting in a third densification and bonding of the powder particles.

[0046] Boron carbide has strong bonds that make it difficult to densify and sinter. Currently, high-performance boron carbide ceramics are mostly prepared by hot pressing, but this method has the disadvantage of low production capacity. This scheme uses a shrinkage sintering process and secondary densification pressing to densify the multiphase ceramic green body multiple times, improving the tight bonding between particles and leveraging the reinforcing and toughening effects of boron carbide and β-SiC.

[0047] S8. Pressureless sintering: Pressureless sintering of α-SiC / B4C composite ceramic green body to obtain α-SiC / B4C composite bulletproof ceramic.

[0048] Among them, the α-SiC powder D 50 ≤0.8μm, purity ≥99.5%;

[0049] The boron carbide powder D 50 ≤0.8μm, purity ≥98.5%.

[0050] In some specific embodiments, the sintering method can be any one of pressureless sintering, hot pressing sintering, and reaction sintering. This invention preferably uses pressureless sintering, which is simple, has a short sintering time, and high production efficiency. The bulletproof ceramic prepared by pressureless sintering is almost completely dense and possesses excellent mechanical properties. Specifically, the sintering temperature is 1950-2000℃, and the holding time is 1-2 hours. Through pressureless sintering, silicon carbide and boron carbide particles are densified through grain growth and bonding, resulting in the α-SiC / B4C composite bulletproof ceramic product.

[0051] Furthermore, the raw material also includes 8-15 parts of β-SiC powder, wherein the β-SiC powder D 50 ≤100nm, purity ≥99.9%. Due to its excellent properties in terms of strength, hardness, wear resistance, thermal conductivity, and sintering activity, β-SiC powder can be added to silicon carbide matrix materials to improve the strength of ceramic materials and prepare highly protective α / β-SiC / B4C composite bulletproof ceramics.

[0052] It is worth noting that the process temperature and process time involved in the above embodiments are all temperatures or times used in the experiment. Any reasonable adjustments made by those skilled in the art based on the process temperature and process time provided by the present invention, within the error range, should be included within the protection scope of the present invention. Dispersants, organic additives, and sintering aids are preferred embodiments of the present invention and can be used alone or in combination, or other alternative solutions can be selected.

[0053] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below through experimental examples.

[0054] Experimental materials:

[0055] The α-SiC powder was sourced from Ningxia Northern High-Tech Industrial Co., Ltd.; the β-SiC powder was provided by the State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals, Lanzhou University of Technology; and the B4C powder was sourced from Jianapu Materials Technology Co., Ltd. All other formulations involved in this invention are commercially available standard formulations.

[0056] Performance testing methods and instruments:

[0057] Performance testing was conducted according to the GB / T national standard. The Vickers hardness of the composite bulletproof ceramic was tested using a microhardness tester; the fracture toughness and flexural strength of the composite bulletproof ceramic were tested using a universal testing machine; and the density was determined using the Archimedes displacement method.

[0058] Comparative Example 1:

[0059] A method for preparing silicon carbide ceramics, comprising the following materials: 80 parts α-SiC powder, 20 parts B4C powder, 0.8 parts sodium lignosulfonate, 0.8 parts ethylene oxide, 8 parts PVA, 7 parts PEG, 0.5 parts n-butanol, and 1.5 parts stearic acid. The preparation steps are as follows:

[0060] Powder dispersion: Add sodium lignosulfonate to 1000g of deionized water and stir for 30min, then add D 50 α-SiC powder with a particle size ≤0.8μm and a purity ≥99.5% was stirred at 40℃ for 1-2 hours to obtain an α-SiC dispersion solution. Ethylene oxide was added to 500g of deionized water and stirred for 30-40 minutes, followed by the addition of D... 50 B4C powder with a particle size of ≤0.8μm and a purity of ≥98.5% was ultrasonically stirred for 1-2 hours to obtain a uniform, stable, and highly dispersible B4C dispersion solution.

[0061] Ingredients: The above α-SiC and B4C dispersion solutions were mixed and stirred at room temperature for 45 min, PVA and PEG were added, and the mixture was ball-milled at 1008 r / min for 1.5 h. Then, n-butanol and stearic acid were added to the ball mill jar and the mixture was ball-milled for 12 h.

[0062] Water-based spray granulation: The slurry of α-SiC / B4C mixture is sprayed and granulated using a spray granulation tower. The spray granulation parameters are set as follows: inlet temperature 210-240℃, outlet temperature 90-110℃, and atomizing disc rotation speed 10-13Hz, to produce granulated powder balls of 70-150μm.

[0063] First dry pressing: The α-SiC / B4C granulated powder is pressed into α-SiC / B4C ceramic blanks of a certain size by a hydraulic press with a pressure of 9MPa, so as to densify the powder particles and make the powder particles reasonably distributed and tightly bonded.

[0064] Pressureless sintering: sintering temperature 1950-2000℃, holding time 1-2h, to obtain silicon carbide ceramics.

[0065] Performance testing: The prepared silicon carbide ceramics were subjected to performance testing, and the test results are shown in Table 1.

[0066] Table 1. Performance of silicon carbide ceramics in Comparative Example 1

[0067]

[0068] As can be seen from Comparative Example 1, under traditional process conditions, ceramics without added β-SiC have lower flexural strength, Vickers hardness, and fracture toughness, resulting in poor overall performance.

[0069] Experiment 1: Exploring the Influence of β-SiC on the Performance of Bulletproof Ceramic under Traditional Processing Conditions

[0070] A method for preparing composite silicon carbide ceramics, comprising the following materials: 80 parts α-SiC powder, 20 parts B4C powder, β-SiC powder added according to the fractions shown in Table 2, 0.8 parts sodium lignosulfonate, 0.8 parts ethylene oxide, 8 parts PVA, 7 parts PEG, 0.5 parts n-butanol, and 1.5 parts stearic acid. The preparation steps are as follows:

[0071] Powder dispersion: Add sodium lignosulfonate to 1000g of deionized water and stir for 30min, then add D 50 α-SiC powder with a particle size ≤0.8μm and a purity ≥99.5% in D 50 β-SiC powder with a particle size ≤100 nm and a purity ≥99.9% was stirred at 40℃ for 1-2 hours to obtain an α / β-SiC dispersion solution. Ethylene oxide was added to 500g of deionized water and stirred for 30-40 minutes, followed by the addition of D... 50 B4C powder with a particle size of ≤0.8μm and a purity of ≥98.5% was ultrasonically stirred for 1-2 hours to obtain a uniform, stable, and highly dispersible B4C dispersion solution.

[0072] Ingredients: The above α / β-SiC dispersion and B4C dispersion were mixed and stirred at room temperature for 45 min. PVA and PEG were added and ball milled at 1008 r / min for 1.5 h. Then, n-butanol and stearic acid were added to the ball mill jar and ball milled for 12 h.

[0073] Water-based spray granulation: The slurry of α / β-SiC mixture is sprayed and granulated using a spray granulation tower. The spray granulation parameters are set as follows: inlet temperature 210-240℃, outlet temperature 90-110℃, and atomizing disc rotation speed 10-13Hz, to produce granulated powder balls of 70-150μm.

[0074] Dry pressing: Boron carbide granulated powder is pressed into α / β-SiC ceramic blanks of a certain size using a hydraulic press with a pressure of 9MPa, thereby densifying the powder particles and ensuring that the powder particles are reasonably distributed and tightly bonded.

[0075] Pressureless sintering: sintering temperature 1950-2000℃, holding time 1-2h, to obtain composite silicon carbide ceramics.

[0076] Performance testing: The performance of the prepared composite silicon carbide ceramics was tested, and the test results are shown in Table 3.

[0077] Table 2 Material Proportions for Experiment 1

[0078]

[0079] Table 3 Performance of Composite Silicon Carbide Ceramics in Experiment 1

[0080]

[0081]

[0082] The above experiments show that the performance of the ceramic is improved by adding a small amount of β-SiC. When 12 parts of β-SiC are added, the flexural strength of the ceramic reaches 497 MPa, the Vickers hardness reaches 2575 HV, and the fracture toughness reaches 4.88 MPa. 1 / 2 However, with the continued increase of β-SiC, the various properties of the ceramic gradually decrease. Although the ceramic performance reaches its peak when β-SiC is added to 12 parts, it still cannot meet practical requirements.

[0083] Experiment 2: Exploring the effects of shrinkage sintering process and secondary densification pressing on the performance of bulletproof ceramics.

[0084] Experiment 2.1:

[0085] A method for preparing silicon carbide ceramics, comprising the following materials: 80 parts α-SiC powder, 20 parts B4C powder, 0.8 parts sodium lignosulfonate, 0.8 parts ethylene oxide, 8 parts PVA, 7 parts PEG, 0.5 parts n-butanol, and 1.5 parts stearic acid. The preparation steps are as follows:

[0086] Powder dispersion: Add sodium lignosulfonate to 1000g of deionized water and stir for 30min, then add D 50 α-SiC powder with a particle size ≤0.8μm and a purity ≥99.5% was stirred at 40℃ for 1-2 hours to obtain an α-SiC dispersion solution. Ethylene oxide was added to 500g of deionized water and stirred for 30-40 minutes, followed by the addition of D... 50 B4C powder with a particle size of ≤0.8μm and a purity of ≥98.5% was ultrasonically stirred for 1-2 hours to obtain a uniform, stable, and highly dispersible B4C dispersion solution.

[0087] Ingredients: The above α-SiC and B4C dispersion solutions were mixed and stirred at room temperature for 45 min, PVA and PEG were added, and the mixture was ball-milled at 1008 r / min for 1.5 h. Then, n-butanol and stearic acid were added to the ball mill jar and the mixture was ball-milled for 12 h.

[0088] Water-based spray granulation: The slurry of α-SiC / B4C mixture is sprayed and granulated using a spray granulation tower. The spray granulation parameters are set as follows: inlet temperature 210-240℃, outlet temperature 90-110℃, and atomizing disc rotation speed 10-13Hz, to produce granulated powder balls of 70-150μm.

[0089] Dry pressing: Boron carbide granulated powder is pressed into α-SiC / B4C ceramic blanks of a certain size using a hydraulic press with a pressure of 9MPa, thereby densifying the powder particles and ensuring that the powder particles are reasonably distributed and tightly bonded.

[0090] Shrinkage sintering: The dry-pressed multiphase ceramic green body is placed in a vacuum sintering furnace, and the furnace is heated to 300℃±10℃. Sintering is carried out at this temperature for 40-60 minutes.

[0091] Secondary densification pressing: The sintered and shrunken multiphase ceramic green body is extruded again using an isostatic press at a pressure of 80-100 MPa.

[0092] Pressureless sintering: sintering temperature 1950-2000℃, holding time 1-2h, to obtain silicon carbide ceramics.

[0093] Performance testing: The prepared silicon carbide ceramics were subjected to performance testing, and the test results are shown in Table 4.

[0094] Table 4. Performance of Silicon Carbide Ceramics in Experiment 2.1

[0095]

[0096] As shown in Table 4, without the addition of β-SiC, the shrinkage sintering process and secondary densification pressing of this scheme improve all properties of silicon carbide ceramics compared with the traditional process, i.e., the process conditions of Comparative Example 1, but the improvement effect is not significant.

[0097] Experiment 2.2:

[0098] The preparation method for silicon carbide ceramics involves preparing materials according to Table 5. The preparation steps are as follows:

[0099] Powder dispersion: Add polyacrylic acid to 1000g of deionized water and stir for 30min, then add D. 50 α-SiC powder with a particle size ≤0.8μm and a purity ≥99.5% was stirred at 40℃ for 1-2 hours to obtain an α-SiC dispersion solution. Polyoxypropylene was added to 500g of deionized water and stirred for 30-40 minutes, followed by the addition of D... 50 B4C powder with a particle size of ≤0.8μm and a purity of ≥98.5% was ultrasonically stirred for 1-2 hours to obtain a uniform, stable, and highly dispersible B4C dispersion solution.

[0100] Ingredients: The above α-SiC and B4C dispersion solutions were mixed and stirred at room temperature for 45 min, PVA and PEG were added, and the mixture was ball-milled at 1008 r / min for 1.5 h. Then, n-butanol and stearic acid were added to the ball mill jar and the mixture was ball-milled for 12 h.

[0101] Water-based spray granulation: The slurry of α-SiC / B4C mixture is sprayed and granulated using a spray granulation tower. The spray granulation parameters are set as follows: inlet temperature 210-240℃, outlet temperature 90-110℃, and atomizing disc rotation speed 10-13Hz, to produce granulated powder balls of 70-150μm.

[0102] Dry pressing: Boron carbide granulated powder is pressed into α-SiC / B4C ceramic blanks of a certain size using a hydraulic press with a pressure of 9MPa, thereby densifying the powder particles and ensuring that the powder particles are reasonably distributed and tightly bonded.

[0103] Shrinkage sintering: The dry-pressed multiphase ceramic green body is placed in a vacuum sintering furnace, and the furnace is heated to 300℃±10℃. Sintering is carried out at this temperature for 40-60 minutes.

[0104] Secondary densification pressing: The sintered and shrunken multiphase ceramic green body is extruded again using an isostatic press at a pressure of 80-100 MPa.

[0105] Pressureless sintering: sintering temperature 1950-2000℃, holding time 1-2h, to obtain silicon carbide ceramics.

[0106] Performance testing: The prepared silicon carbide ceramics were subjected to performance testing, and the test results are shown in Table 6.

[0107] Table 5. Performance of Silicon Carbide Ceramics in Experiment 2.2

[0108]

[0109] Table 6. Performance of Silicon Carbide Ceramics in Experiment 2.2

[0110]

[0111] As can be seen from Table 6, adjusting the weight parts of B4C, dispersant, organic additives, and sintering aids, the properties of the resulting silicon carbide ceramics are not significantly different from those in Experiment 2.1.

[0112] Experiment 3: Exploring the effect of adding β-SiC on the performance of bulletproof ceramics under shrinkage sintering process and secondary densification pressing conditions.

[0113] A method for preparing composite silicon carbide ceramics, comprising the following materials: 80 parts α-SiC powder, 20 parts B4C powder, β-SiC powder added according to the proportions shown in Table 7, 1 part sodium lignosulfonate, 0.5 parts ethylene oxide, 8 parts PVA, 7 parts PEG, 0.5 parts n-butanol, and 1.5 parts stearic acid. The preparation steps are as follows:

[0114] Powder dispersion: Add sodium lignosulfonate to 1000g of deionized water and stir for 30min, then add D 50 α-SiC powder with a particle size ≤0.8μm and a purity ≥99.5% in D 50 β-SiC powder with a particle size ≤100 nm and a purity ≥99.9% was stirred at 40℃ for 1-2 hours to obtain an α / β-SiC dispersion solution. Ethylene oxide was added to 500g of deionized water and stirred for 30-40 minutes, followed by the addition of D... 50 B4C powder with a particle size of ≤0.8μm and a purity of ≥98.5% was ultrasonically stirred for 1-2 hours to obtain a uniform, stable, and highly dispersible B4C dispersion solution.

[0115] Ingredients: The above α / β-SiC dispersion and B4C dispersion were mixed and stirred at room temperature for 45 min. PVA and PEG were added and ball milled at 1008 r / min for 1.5 h. Then, n-butanol and stearic acid were added to the ball mill jar and ball milled for 12 h.

[0116] Water-based spray granulation: The slurry of α / β-SiC mixture is sprayed and granulated using a spray granulation tower. The spray granulation parameters are set as follows: inlet temperature 210-240℃, outlet temperature 90-110℃, and atomizing disc rotation speed 10-13Hz, to produce granulated powder balls of 70-150μm.

[0117] Dry pressing: Boron carbide granulated powder is pressed into α / β-SiC ceramic blanks of a certain size using a hydraulic press with a pressure of 9MPa, thereby densifying the powder particles and ensuring that the powder particles are reasonably distributed and tightly bonded.

[0118] Shrinkage sintering: The dry-pressed multiphase ceramic green body is placed in a vacuum sintering furnace, and the furnace is heated to 300℃±10℃. Sintering is carried out at this temperature for 40-60 minutes.

[0119] Secondary densification pressing: The sintered and shrunken multiphase ceramic green body is extruded again using an isostatic press at a pressure of 80-100 MPa.

[0120] Pressureless sintering: sintering temperature 1950-2000℃, holding time 1-2h, to obtain composite silicon carbide ceramics.

[0121] Performance testing: The performance of the prepared composite silicon carbide ceramics was tested, and the test results are shown in Table 8.

[0122] Table 7 Material Proportions for Experiment 3

[0123]

[0124] Table 8. Performance of Composite Silicon Carbide Ceramics in Experiment 3

[0125]

[0126] As shown in Table 8, the addition of β-SiC significantly improves the performance of composite bulletproof ceramics when using shrinkage sintering and secondary densification pressing. In particular, when β-SiC is added to 12 parts, the flexural strength reaches 567 MPa, the Vickers hardness reaches 2696 HV, and the fracture toughness reaches 5.49 MPa. 1 / 2 The performance of the composite bulletproof ceramic is significantly improved compared to ceramics produced by adding only β-SiC or by using only shrinkage sintering and secondary densification pressing. However, the performance of the composite bulletproof ceramic gradually decreases with further addition of β-SiC. Therefore, a β-SiC addition of 12 parts is the optimal ratio for this scheme.

[0127] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing silicon carbide bulletproof ceramic, characterized in that, Includes the following steps: S1. Prepare the raw materials according to the following parts by weight: 80 parts of α-SiC powder, 20-30 parts of boron carbide powder, 0.8-1 parts of the first dispersant, 0.5-0.8 parts of the second dispersant, 10-18 parts of organic additives, and 0.5-2 parts of sintering aids; S2. Powder dispersion: α-SiC powder and the first dispersant are dispersed in deionized water to obtain an α-SiC dispersion solution; boron carbide powder and the second dispersant are dispersed in deionized water to obtain a boron carbide dispersion solution. S3. Ingredient preparation: Mix and stir the α-SiC dispersion solution and the boron carbide dispersion solution, add organic additives and ball mill for 1-2 hours, then add sintering aids and ball mill to obtain α-SiC / B4C mixed slurry; S4. Water-based spray granulation: spray granulation of α-SiC / B4C mixed slurry into granulated powder pellets; S5. First dry pressing molding, pressing granulated powder pellets into α-SiC / B4C multiphase ceramic green body; S6. Shrinkage sintering: The α-SiC / B4C multiphase ceramic green body, which was first dry-pressed, was heated to 300℃±10℃ and vacuum sintered for 40-60 min. S7. Secondary densification pressing: The α-SiC / B4C multiphase ceramic green body after shrinkage sintering is subjected to secondary densification pressing at 80-100 MPa. S8. Pressureless sintering: Pressureless sintering of α-SiC / B4C multiphase ceramic green body to obtain α-SiC / B4C composite bulletproof ceramic; Among them, the α-SiC powder D 50 ≤ 0.8 µm, purity ≥ 99.5%; The boron carbide powder D 50 ≤ 0.8 µm, purity ≥ 98.5%.

2. The method for preparing silicon carbide bulletproof ceramic according to claim 1, characterized in that, The first dispersant is ammonium polyacrylate or sodium lignosulfonate.

3. The method for preparing silicon carbide bulletproof ceramic according to claim 1, characterized in that, The second dispersant is polyoxypropylene or ethylene oxide.

4. The method for preparing silicon carbide bulletproof ceramic according to claim 2, characterized in that, The organic additive is a mixture of polyvinyl alcohol and polyethylene glycol, wherein the mass ratio of polyvinyl alcohol to polyethylene glycol is (5-8):(5-10).

5. The method for preparing silicon carbide bulletproof ceramic according to claim 2, characterized in that, The sintering aid is a mixture of n-butanol and stearic acid, wherein the mass ratio of n-butanol to stearic acid is 1:

3.

6. The method for preparing silicon carbide bulletproof ceramic according to claim 1, characterized in that, The raw materials also include 8-15 parts of β-SiC powder, wherein the β-SiC powder D 50 ≤ 100 nm, purity ≥ 99.9%.

7. A silicon carbide bulletproof ceramic, characterized in that, It is prepared by the method of any one of claims 1-6 for preparing silicon carbide bulletproof ceramic.

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