A metal-based toughened multiphase anti-bullet ceramic and its preparation method

Abstract

A metal-based toughened composite ballistic ceramic, comprising a ceramic main material, a metal toughening agent, and a sintering aid. The ceramic main material comprises B4C powder, SiC powder, TiO2, nanocarbon black, and Si powder; the metal toughening agent is composed of at least three of WB, MoB, CrB, and VB; and the sintering aid is composed of glucose and polyvinyl pyrrolidone. The toughening agent is dispersed throughout the grain boundaries during sintering, achieving synergistic reinforcement of high hardness and high toughness, reaching a hardness of 34.9 GPa and a fracture toughness of 8.8 MPa·m. 1 / 2 The prepared metal-based toughened complex phase anti-ballistic ceramics improve the protective equipment's ability to resist multiple strikes and can defend against up to 8 consecutive strikes.

Description

Technical Field

[0001] The present invention relates to the technical field of preparation of ballistic-resistant ceramics, and in particular to a metal-based toughened multiphase ballistic-resistant ceramic and a preparation method thereof. Background Art

[0002] Boron carbide and silicon carbide are important structural ceramics. Due to their low density and ultra-high hardness, they are widely used in individual soldier protection, armed helicopters, armored vehicles and other fields.

[0003] The synergistic effect of high hardness and high toughness in bullet-resistant ceramics is crucial for resisting multiple rounds of bullets. However, boron carbide and silicon carbide are strong covalent bond compounds with high resistance to grain boundary movement. The surface tension of solid boron carbide is very small. Therefore, the diffusion rate is low during sintering, and it is difficult for ceramic particles to shrink and densify. It is very difficult to obtain highly densified ceramics, which ultimately results in insufficient fracture toughness. After the first projectile hits, they shatter severely and cannot meet the needs of resisting multiple rounds of bullets under actual combat conditions. Boron carbide and silicon carbide ceramics are relatively brittle and have relatively low fracture toughness. Existing toughening technologies have greatly improved the hardness, fracture toughness and other single properties of the material, but it is difficult to achieve high hardness and high toughness at the same time. For example, patent CN113149676 A discloses boron carbide prepared by a two-step firing process through optimized sintering technology. Although densification and fracture toughness are improved to a certain extent, hardness is sacrificed. Existing technologies also add toughening phases to improve the toughness of ceramics, but since high hardness and high toughness cannot be guaranteed simultaneously, it is difficult to achieve a synergistic effect. When ceramic boron carbide materials prepared in this way are used in ballistic tests, they are very likely to break after being hit by projectiles, and their ballistic performance is poor.

[0004] At present, the more mature process for preparing high-density boron carbide is hot pressing sintering. The sintering temperature is generally above 2000℃. The high temperature hot pressing causes particle rearrangement and plastic flow, grain boundary movement, strain-induced twinning, creep, and the migration of materials such as volume diffusion and recrystallization in the later stage, which promotes the densification of boron carbide ceramics. However, the hot pressing sintering method has low production efficiency and high cost, making it difficult to achieve large-scale production. However, if you want to obtain high-density boron carbide ceramics by using normal pressure sintering, you need to sinter at extremely high temperatures, which is very likely to cause abnormal grain growth and particle surface melting, thereby resulting in a decrease in the performance of boron carbide ceramics. Studies have shown that by adding sintering aids to increase the density of point defects and dislocations, thereby promoting the activation of grain boundaries and volume diffusion, improving the densification of boron carbide, and at the same time reducing the sintering temperature to a certain extent. The addition of sintering aids will also lead to a reduction in the hardness of the material to varying degrees.

[0005] Therefore, it is urgent to carry out research on the synergistic strengthening of high hardness and high toughness of bullet-resistant ceramics to improve the ceramics' resistance to multiple bullets. Summary of the Invention

[0006] The present invention aims to provide a metal-based toughened multiphase anti-bullet ceramic.

[0007] Another object of the present invention is to provide a method for preparing the aforementioned metal-based toughened multiphase ballistic-resistant ceramic. This method addresses the problem of insufficient resistance to multiple strikes in existing protective equipment. By dispersing nanocrystals within the ceramic phase, a synergistic enhancement of high hardness and high toughness is achieved, ultimately significantly improving the ceramic's resistance to multiple strikes.

[0008] The purpose of the present invention is achieved through the following technical solutions:

[0009] A metal-based toughened multiphase ballistic ceramic, characterized in that the raw materials of the ballistic ceramic include a ceramic main material, a metal toughening agent and a sintering aid, wherein the ceramic main material includes B4C powder, SiC powder, TiO2, nano-carbon black and Si powder, the metal toughening agent is composed of at least three of WB, MoB, CrB and VB, and the sintering aid is composed of glucose and polyvinyl pyrrolidone.

[0010] Preferably, the metal toughening agent is composed of WB, MoB, CrB and VB in a mass ratio of 3:1:1:1.

[0011] Furthermore, in terms of mass percentage, B4C powder is 450-70%, SiC powder is 10-15%, TiO2 is 2-5%, nano carbon black is 2-5%, Si powder is 5-10%, metal toughening agent is 5-8%, glucose is 5-10%, and polyvinyl pyrrolidone is 1-5%.

[0012] The preparation method of the above-mentioned metal-based toughened complex phase anti-ballistic ceramic is characterized by: including raw material powder preparation, embryo pressing and sintering treatment, the sintering treatment is pressureless sintering, specifically two-stage sintering under Ar gas protection, the first stage of sintering is to heat up to 1200±10℃ at 3~5℃ / min, keep warm and pressure for 50~60min, and the second stage of sintering is to heat up to 1850±10℃ at 3~4℃ / min and keep warm for 40~50min.

[0013] Furthermore, the embryo body pressing is to place the raw material powder in a mold, apply a pressure of 5±1 MPa, maintain the pressure for 6 to 10 hours, then pressurize to 15±1 MPa, maintain the pressure for 3 to 5 hours, and finally pressurize to 30±1 MPa, and maintain the pressure for 1 to 2 hours.

[0014] Furthermore, the preparation of the raw material powder is divided into three steps. Specifically, nano carbon black and polyvinyl pyrrolidone are mixed and ball-milled to prepare powder A. The second step is to mix powder A, ceramic main material and glucose and ball-mill to prepare powder B. The third step is to mix powder B and toughening agent and ball-mill to prepare powder C.

[0015] Furthermore, the powder A is prepared by adding nano carbon black and polyvinyl pyrrolidone to deionized water, then planetary ball milling, with a liquid-to-material volume ratio of 1:1, a ball-to-material ratio of 2:1, a ball milling speed of 300-400 r / min, a ball milling time of 8-12 h, and then drying to obtain powder A.

[0016] Furthermore, the preparation of powder B is to add powder A, B4C powder, SiC powder, TiO2, Si powder and glucose to anhydrous ethanol for wet grinding, with a liquid-to-material volume ratio of 3:1, a ball-to-material ratio of 3:1, a ball mill speed of 200-300 r / min, a ball milling time of 12-15 h, and after drying, pass through a 100 mesh sieve to obtain powder B.

[0017] Furthermore, the powder C is prepared by adding powder B and a toughening agent to anhydrous ethanol for wet grinding, with a liquid-to-material ratio of 1:1, a ball-to-material ratio of 1:1, a ball mill speed of 100-200 r / min, a ball milling time of 20-24 h, and then drying to obtain powder C.

[0018] During the preparation process, it was found that due to the pressureless sintering process, only temperature acts, so it is very difficult to sinter compounds with higher covalency such as boron carbide and silicon carbide. Moreover, after adding a toughening agent, the dispersion distribution effect of the toughening phase during the sintering process is not ideal, resulting in the toughening effect not meeting expectations. Therefore, it is necessary to reasonably match factors such as powder, toughening agent, sintering aid, and sintering process to obtain a dense sintered body. By adding a boride component as a toughening agent in a proportioned composite ratio, the sintering densification of boron carbide is effectively promoted, and its mechanical properties are improved at the same time. By using glucose and PVP as a composite sintering aid, surface diffusion and evaporation are effectively prevented during the sintering process, and grain boundary motion is controlled. Under this effect, the toughening agent of the composite ratio prevents grain growth, produces a pinning effect, and a eutectic phenomenon occurs under the staged sintering process, producing liquid phase sintering, so that at a lower pressureless sintering temperature, a ceramic material with high density can still be sintered, while ensuring the mechanical properties such as the toughness and hardness of the ceramic.

[0019] Most specifically, a method for preparing a metal-based toughened multiphase anti-bullet ceramic is characterized by comprising the following steps:

[0020] (1) Formulation design

[0021] The ceramic main materials include B4C powder, SiC powder, TiO2, nano-carbon black and Si powder, at least three of WB, MoB, CrB and VB form toughening agents, glucose and polyvinyl pyrrolidone are sintering aids, and according to mass percentage, B4C powder accounts for 45-70%, SiC powder accounts for 10-15%, TiO2 accounts for 2-5%, nano-carbon black accounts for 2-5%, Si powder accounts for 5-10%, metal toughening agent accounts for 5-8%, glucose accounts for 5-10%, and polyvinyl pyrrolidone accounts for 1-5%.

[0022] (2) Powder preparation

[0023] Powder A: Add nano-carbon black and polyvinyl pyrrolidone to deionized water at a liquid-to-solid volume ratio of 1:1, perform planetary ball milling at a ball-to-solid ratio of 2:1, a ball milling speed of 300-400 rpm, and a ball milling time of 8-12 h. Then, dry at 80-100°C for 6-8 h to obtain powder A.

[0024] Powder B: Add powder A, B4C powder, SiC powder, TiO2, Si powder and glucose to anhydrous ethanol with a liquid-to-material volume ratio of 3:1, and perform planetary ball milling with a ball-to-material ratio of 3:1 at a ball milling speed of 200-300 rpm for 12-15 hours. Then, dry at 100-120°C for 10-12 hours and pass through a 100-mesh sieve to obtain powder B.

[0025] Powder C: Powder B and a metal toughening agent were added to anhydrous ethanol at a liquid-to-material volume ratio of 1:1, and subjected to planetary ball milling at a ball-to-material ratio of 1:1, a ball milling speed of 100-200 r / min, and a ball milling time of 20-24 h. Powder C was then dried at 50-70°C for 8-10 h to obtain powder C.

[0026] (3) Embryo compression

[0027] Weigh powder C and place it in a steel mold. Evenly coat the inner wall of the mold with BN to prevent sticking. Apply a pressure of 5±1MPa and maintain it for 6-10h. Then increase the pressure to 15±1MPa and maintain it for 3-5h. Finally, increase the pressure to 30±1MPa and maintain it for 1-2h.

[0028] (4) Sintering treatment

[0029] Place the embryo prepared in step (3) in a vacuum sintering furnace, evacuate the furnace and fill it with Ar gas for protection, heat it to 1200±10℃ at 3~5℃ / min, keep it warm and pressurize for 50~60min, then heat it to 1850±10℃ at 3~4℃ / min, keep it warm for 40~45min, turn off the heating system, cool it to 50~60℃ with the furnace, turn off the vacuum system and take out the sample.

[0030] The present invention has the following technical effects:

[0031] In the present invention, the toughening agent is dispersed in the grain boundary during the sintering process to achieve synergistic strengthening of high hardness and high toughness, with the hardness reaching 34.9GPa and the fracture toughness reaching 8.8MPa·m 1 / 2 The prepared metal-based toughened complex phase anti-ballistic ceramics improve the protective equipment's ability to resist multiple strikes and can defend against up to 8 consecutive strikes. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 : The pressureless sintering process curve adopted by the present invention.

[0033] Figure 2 : Scanning electron microscope image of the surface morphology of the ceramic material prepared in Example 1.

[0034] Figure 3 : Scanning electron microscope image of the surface morphology of the ceramic material prepared in Comparative Example 1.

[0035] Figure 4 : Scanning electron microscope image of the surface morphology of the ceramic material prepared in Example 2.

[0036] Figure 5 : Scanning electron microscope image of the surface morphology of the ceramic material prepared in Example 3. DETAILED DESCRIPTION

[0037] The present invention is described in detail below through examples. It is necessary to point out that the following examples are only used to further illustrate the present invention and are not to be construed as limiting the scope of protection of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention based on the above-mentioned contents of the present invention.

[0038] Example 1

[0039] A method for preparing a metal-based toughened multiphase anti-bullet ceramic comprises the following steps:

[0040] (1) Formulation design

[0041] B4C powder, SiC powder, TiO2, nano-carbon black and Si powder are used as the main ceramic materials, WB, MoB, and CrB are composed of toughening agents in a mass ratio of 3:1:1, glucose and polyvinyl pyrrolidone are used as sintering aids, and in terms of mass percentage, B4C powder is 58%, SiC powder is 12%, TiO2 is 4%, nano-carbon black is 4%, Si powder is 6%, metal toughening agent is 6%, glucose is 6%, and polyvinyl pyrrolidone is 4%;

[0042] (2) Powder preparation

[0043] Powder A: Nano carbon black and polyvinyl pyrrolidone were added to deionized water at a liquid-to-solid volume ratio of 1:1, and subjected to planetary ball milling at a ball-to-solid ratio of 2:1 at a ball milling speed of 350 rpm for 10 h, followed by drying to obtain powder A.

[0044] Powder B: Powder A, B4C powder, SiC powder, TiO2, Si powder and glucose were added to anhydrous ethanol with a liquid-to-material volume ratio of 3:1. The mixture was subjected to planetary ball milling with a ball-to-material ratio of 3:1 and a ball milling speed of 250 rpm for 12 h. After drying, the powder was sieved through a 100-mesh sieve to obtain powder B.

[0045] Powder C: Powder B and a metal toughening agent were added to anhydrous ethanol at a liquid-to-solid volume ratio of 1:1. The mixture was subjected to planetary ball milling at a ball-to-solid ratio of 1:1, a ball milling speed of 150 r / min, and a ball milling time of 22 h. The mixture was then dried to obtain powder C.

[0046] (3) Embryo compression

[0047] Weigh powder C and place it in a steel mold. Evenly coat the inner wall of the mold with BN to prevent sticking. Apply a pressure of 5 MPa and hold it for 8 hours. Then increase the pressure to 15 MPa and hold it for 4 hours. Finally, increase the pressure to 30 MPa and hold it for 1.5 hours.

[0048] (4) Sintering

[0049] The embryo prepared in step (3) was placed in a vacuum sintering furnace, vacuumed and filled with Ar gas for protection, heated to 1200°C at 3°C / min, kept warm and pressure-maintained for 60 minutes, then heated to 1850°C at 4°C / min, kept warm for 40 minutes, the heating system was turned off, and the furnace was cooled to 55°C. The vacuum system was then turned off and the sample was taken out.

[0050] Comparative Example 1

[0051] Compared with Example 1, the toughening agent used is WB, MoB, and TiB2 in a mass ratio of 3:1:1, and the other steps are consistent with Example 1.

[0052] Comparative Example 2

[0053] Compared with Example 1, the difference is that the powder preparation process adopts one-step ball milling, and the remaining steps are consistent with the example. The preparation steps are as follows:

[0054] (1) Formulation design

[0055] B4C powder, SiC powder, TiO2, nano-carbon black and Si powder are used as the main ceramic materials, WB, MoB, and CrB are composed of toughening agents in a mass ratio of 3:1:1, glucose and polyvinyl pyrrolidone are used as sintering aids, and in terms of mass percentage, B4C powder is 58%, SiC powder is 12%, TiO2 is 4%, nano-carbon black is 4%, Si powder is 6%, metal toughening agent is 6%, glucose is 6%, and polyvinyl pyrrolidone is 4%;

[0056] (2) Powder preparation

[0057] B4C powder, SiC powder, TiO2, nano carbon black, Si powder, glucose, polyvinyl pyrrolidone and metal toughening agent were added to deionized water at a liquid-to-material volume ratio of 1:1, and subjected to planetary ball milling at a ball-to-material ratio of 3:1, a ball milling speed of 350 rpm, and a ball milling time of 45 h, and then dried to obtain powder;

[0058] (3) Embryo compression

[0059] Weigh powder C and place it in a steel mold. Evenly coat the inner wall of the mold with BN to prevent sticking. Apply a pressure of 5 MPa and hold it for 8 hours. Then increase the pressure to 15 MPa and hold it for 4 hours. Finally, increase the pressure to 30 MPa and hold it for 1.5 hours.

[0060] (4) Sintering

[0061] The embryo prepared in step (3) was placed in a vacuum sintering furnace, vacuumed and filled with Ar gas for protection, heated to 1200°C at 3°C / min, kept warm and pressure-maintained for 60 minutes, then heated to 1850°C at 4°C / min, kept warm for 40 minutes, the heating system was turned off, and the furnace was cooled to 55°C. The vacuum system was then turned off and the sample was taken out.

[0062] Example 2

[0063] A method for preparing a metal-based toughened multiphase anti-bullet ceramic comprises the following steps:

[0064] (1) Formulation design

[0065] B4C powder, SiC powder, TiO2, nano-carbon black and Si powder are used as the main ceramic materials, WB, MoB, CrB and VB are composed of toughening agents in a mass ratio of 3:1:1:1, glucose and polyvinyl pyrrolidone are used as sintering aids, and in terms of mass percentage, B4C powder is 58%, SiC powder is 12%, TiO2 is 4%, nano-carbon black is 4%, Si powder is 6%, metal toughening agent is 6%, glucose is 6%, and polyvinyl pyrrolidone is 4%;

[0066] (2) Powder preparation

[0067] Powder A: Nano carbon black and polyvinyl pyrrolidone were added to deionized water at a liquid-to-solid volume ratio of 1:1, and subjected to planetary ball milling at a ball-to-solid ratio of 2:1 at a ball milling speed of 350 rpm for 10 h, followed by drying to obtain powder A.

[0068] Powder B: Powder A, B4C powder, SiC powder, TiO2, Si powder and glucose were added to anhydrous ethanol with a liquid-to-material volume ratio of 3:1. The mixture was subjected to planetary ball milling with a ball-to-material ratio of 3:1 and a ball milling speed of 250 rpm for 12 h. After drying, the powder was sieved through a 100-mesh sieve to obtain powder B.

[0069] Powder C: Powder B and a metal toughening agent were added to anhydrous ethanol at a liquid-to-solid volume ratio of 1:1. The mixture was subjected to planetary ball milling at a ball-to-solid ratio of 1:1, a ball milling speed of 150 r / min, and a ball milling time of 22 h. The mixture was then dried to obtain powder C.

[0070] (3) Embryo compression

[0071] Weigh powder C and place it in a steel mold. Evenly coat the inner wall of the mold with BN to prevent sticking. Apply a pressure of 5 MPa and hold it for 8 hours. Then increase the pressure to 15 MPa and hold it for 4 hours. Finally, increase the pressure to 30 MPa and hold it for 1.5 hours.

[0072] (4) Sintering

[0073] The embryo prepared in step (3) was placed in a vacuum sintering furnace, vacuumed and filled with Ar gas for protection, heated to 1200°C at 3°C / min, kept warm and pressure-maintained for 60 minutes, then heated to 1850°C at 4°C / min, kept warm for 40 minutes, the heating system was turned off, and the furnace was cooled to 55°C. The vacuum system was then turned off and the sample was taken out.

[0074] Comparative Example 3

[0075] The difference from Example 2 is that the green body pressing and sintering process adopts a one-step sintering process, and the remaining steps are the same as Example 2. The specific steps are as follows:

[0076] (1) Formulation design

[0077] B4C powder, SiC powder, TiO2, nano-carbon black and Si powder are used as the main ceramic materials, WB, MoB, CrB and VB are composed of toughening agents in a mass ratio of 3:1:1:1, glucose and polyvinyl pyrrolidone are used as sintering aids, and in terms of mass percentage, B4C powder is 58%, SiC powder is 12%, TiO2 is 4%, nano-carbon black is 4%, Si powder is 6%, metal toughening agent is 8%, glucose is 6%, and polyvinyl pyrrolidone is 4%;

[0078] (2) Powder preparation

[0079] Powder A: Nano carbon black and polyvinyl pyrrolidone were added to deionized water at a liquid-to-solid volume ratio of 1:1, and subjected to planetary ball milling at a ball-to-solid ratio of 2:1 at a ball milling speed of 350 rpm for 10 h, followed by drying to obtain powder A.

[0080] Powder B: Powder A, B4C powder, SiC powder, TiO2, Si powder and glucose were added to anhydrous ethanol with a liquid-to-material volume ratio of 3:1. The mixture was subjected to planetary ball milling with a ball-to-material ratio of 3:1 and a ball milling speed of 250 rpm for 12 h. After drying, the powder was sieved through a 100-mesh sieve to obtain powder B.

[0081] Powder C: Powder B and a metal toughening agent were added to anhydrous ethanol at a liquid-to-solid volume ratio of 1:1. The mixture was subjected to planetary ball milling at a ball-to-solid ratio of 1:1, a ball milling speed of 150 r / min, and a ball milling time of 22 h. The mixture was then dried to obtain powder C.

[0082] (3) Embryo compression

[0083] Powder C was weighed and placed in a steel mold. The inner wall of the mold was evenly coated with BN to prevent sticking. The pressure was increased uniformly from 5 MPa to 30 MPa over 12 hours and maintained for 1.5 hours.

[0084] (4) Sintering

[0085] The embryo prepared in step (3) was placed in a vacuum sintering furnace, evacuated and filled with Ar gas for protection, heated to 1850°C at 4°C / min, kept warm for 40 minutes, and the heating system was turned off. After cooling to 55°C with the furnace, the vacuum system was turned off and the sample was taken out.

[0086] Example 3

[0087] A method for preparing a metal-based toughened multiphase anti-bullet ceramic comprises the following steps:

[0088] (1) Formulation design

[0089] B4C powder, SiC powder, TiO2, nano-carbon black and Si powder are used as the main ceramic materials, MoB, CrB and VB are composed of toughening agents in a mass ratio of 1:1:1, glucose and polyvinyl pyrrolidone are used as sintering aids, and in terms of mass percentage, B4C powder is 45%, SiC powder is 15%, TiO2 is 5%, nano-carbon black is 5%, Si powder is 10%, metal toughening agent is 5%, glucose is 10%, and polyvinyl pyrrolidone is 5%;

[0090] (2) Powder preparation

[0091] Powder A: Nano carbon black and polyvinyl pyrrolidone were added to deionized water at a liquid-to-solid volume ratio of 1:1. The mixture was subjected to planetary ball milling at a ball-to-solid ratio of 2:1 at a ball milling speed of 300 rpm for 12 h. The mixture was then dried at 80°C for 8 h to obtain powder A.

[0092] Powder B: Powder A, B4C powder, SiC powder, TiO2, Si powder and glucose were added to anhydrous ethanol with a liquid-to-material volume ratio of 3:1. The mixture was subjected to planetary ball milling with a ball-to-material ratio of 3:1 and a ball milling speed of 200 rpm for 15 h. The mixture was then dried at 120 °C for 10 h and passed through a 100-mesh sieve to obtain powder B.

[0093] Powder C: Powder B and a metal toughening agent were added to anhydrous ethanol at a liquid-to-solid volume ratio of 1:1. The mixture was subjected to planetary ball milling at a ball-to-solid ratio of 1:1, a ball milling speed of 100 r / min, and a ball milling time of 24 h. The mixture was then dried at 50°C for 10 h to obtain powder C.

[0094] (3) Embryo compression

[0095] Weigh powder C and place it in a steel mold. Evenly coat the inner wall of the mold with BN to prevent sticking. Apply a pressure of 6 MPa and hold it for 6 hours. Then increase the pressure to 14 MPa and hold it for 5 hours. Finally, increase the pressure to 29 MPa and hold it for 2 hours.

[0096] (4) Sintering

[0097] The embryo prepared in step (3) was placed in a vacuum sintering furnace, vacuumed and filled with Ar gas for protection, heated to 1200°C at 4°C / min, kept warm and pressure-maintained for 55 minutes, then heated to 1850°C at 4°C / min, kept warm for 45 minutes, the heating system was turned off, and the furnace was cooled to 55°C. The vacuum system was then turned off and the sample was taken out.

[0098] Example 4

[0099] A method for preparing a metal-based toughened multiphase anti-bullet ceramic comprises the following steps:

[0100] (1) Formulation design

[0101] B4C powder, SiC powder, TiO2, nano-carbon black and Si powder are used as the main ceramic materials, WB, MoB and VB are composed of toughening agents in a mass ratio of 1:1:1, glucose and polyvinyl pyrrolidone are used as sintering aids, and according to mass percentage, B4C powder is 70%, SiC powder is 10%, TiO2 is 2%, nano-carbon black is 2%, Si powder is 5%, metal toughening agent is 5%, glucose is 5%, and polyvinyl pyrrolidone is 1%;

[0102] (2) Powder preparation

[0103] Powder A: Nano carbon black and polyvinyl pyrrolidone were added to deionized water at a liquid-to-solid volume ratio of 1:1. The mixture was subjected to planetary ball milling at a ball-to-solid ratio of 2:1 at a ball milling speed of 400 rpm for 8 h. The mixture was then dried at 100°C for 6 h to obtain powder A.

[0104] Powder B: Powder A, B4C powder, SiC powder, TiO2, Si powder and glucose were added to anhydrous ethanol with a liquid-to-material volume ratio of 3:1. The mixture was subjected to planetary ball milling with a ball-to-material ratio of 3:1 and a ball milling speed of 300 rpm for 12 h. The mixture was then dried at 100°C for 12 h and passed through a 100-mesh sieve to obtain powder B.

[0105] Powder C: Powder B and a metal toughening agent were added to anhydrous ethanol at a liquid-to-solid volume ratio of 1:1. The mixture was subjected to planetary ball milling at a ball-to-solid ratio of 1:1, a ball milling speed of 200 r / min, and a ball milling time of 20 h. The mixture was then dried at 70°C for 8 h to obtain powder C.

[0106] (3) Embryo compression

[0107] Weigh powder C and place it in a steel mold. Evenly coat the inner wall of the mold with BN to prevent sticking. Apply a pressure of 4 MPa and hold it for 10 hours. Then increase the pressure to 16 MPa and hold it for 3 hours. Finally, increase the pressure to 31 MPa and hold it for 1 hour.

[0108] (4) Sintering treatment

[0109] The embryo prepared in step (3) was placed in a vacuum sintering furnace, vacuumed and filled with Ar gas for protection, heated to 1200°C at 4°C / min, kept warm and pressure-maintained for 55 minutes, then heated to 1850°C at 4°C / min, kept warm for 45 minutes, the heating system was turned off, and the furnace was cooled to 55°C. The vacuum system was then turned off and the sample was taken out.

[0110] The mechanical property test results of the ceramic materials prepared in various embodiments and comparative examples are shown in Table 1.

[0111] Table 1: Performance test data of ceramic materials

[0112] Test items Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Relative density (%) 96.8 98.2 97.7 97.0 91.5 92.2 90.4 Vickers hardness (GPa) 33.5 34.9 33.1 33.2 28.7 32.8 30.8 Flexural strength (MPa) 532.2 571.4 558.3 546.9 509.6 523.7 468.5 <![CDATA[Fracture toughness (MPa·m 1 / 2 )]]> 8.2 8.8 8.4 8.2 8.4 6.1 7.2

[0113] Through the coordination of toughening agent, sintering aid, powder preparation, green body pressing and sintering process, the relative density of the ceramic material prepared by pressureless sintering reaches more than 96%, the Vickers hardness is above 33GPa, and the fracture toughness is maintained at 8MPa·m 1 / 2The above results in both effective toughness improvement and high hardness. However, ceramic materials prepared by replacing CrB with other components as a toughening agent maintain a high fracture toughness level, but show a significant decrease in relative density and hardness. The fracture toughness improvement effect of ceramic materials prepared by one-step ball milling is significantly worse than that of the present invention. Furthermore, ceramic materials prepared by green compaction and pressureless sintering using one-step pressing and one-step sintering are not very ideal in terms of hardness and toughness.

[0114] The polished ceramic was composited with ultra-high molecular weight polyethylene sheets to prepare target specimens, which were then subjected to a Type 53 7.62mm incendiary projectile impact test. The test results are shown in Table 2.

[0115] Table 2: Anti-ballistic properties of ceramic materials prepared by various schemes

[0116]

[0117] Ballistic performance tests show that the ceramic material prepared by the present invention, due to its high hardness and toughness, can defend against up to 8 bullet velocities. However, ballistic tests show that a ceramic material prepared using TiB2 instead of CrB as a composite toughening agent can only defend against 3 bullet velocities. The ceramic material prepared using a single-step ball milling process can also only defend against 3 bullet velocities. The ceramic material prepared using a single-step pressing and pressureless sintering process has even worse ballistic performance, defending against only 2 bullet velocities at most.

Claims

1. A method for preparing a metal-based toughened multiphase anti-bullet ceramic, characterized by: The process includes raw material powder preparation, embryo pressing and sintering. The preparation of the raw material powder is divided into three steps. Specifically, the first step is to mix nano carbon black and polyvinyl pyrrolidone and ball mill to prepare powder A. The second step is to mix powder A, B4C powder, SiC powder, TiO2, Si powder and glucose and ball mill to prepare powder B. The third step is to mix powder B and metal toughening agent and ball mill to prepare powder C. The sintering process is pressureless sintering, specifically, two-stage sintering under Ar gas protection. The first stage is to heat the temperature to 1200±10℃ at 3~5℃ / min. The heat and pressure are maintained for 50-60 minutes, and the second stage of sintering is to increase the temperature to 1850±10°C at 3-4°C / min and maintain the temperature for 40-50 minutes. The metal toughening agent is composed of at least three of WB, MoB, CrB and VB. According to the mass percentage, the raw materials include 45-70% B4C powder, 10-15% SiC powder, 2-5% TiO2, 2-5% nano carbon black, 5-10% Si powder, 5-8% metal toughening agent, 5-10% glucose and 1-5% polyvinyl pyrrolidone.

2. The method for preparing a metal-based toughened multiphase anti-bullet ceramic according to claim 1, characterized in that: The embryo body pressing is to place the raw material powder in a mold, apply a pressure of 5±1 MPa, maintain the pressure for 6~10 hours, then pressurize to 15±1 MPa, maintain the pressure for 3~5 hours, and finally pressurize to 30±1 MPa, and maintain the pressure for 1~2 hours.

3. The method for preparing a metal-based toughened multiphase anti-bullet ceramic according to claim 1 or 2, characterized in that: The powder A is prepared by adding nano carbon black and polyvinyl pyrrolidone to deionized water, then planetary ball milling, with a liquid-to-material volume ratio of 1:1, a ball-to-material ratio of 2:1, a ball milling speed of 300-400 r / min, a ball milling time of 8-12 hours, and then drying to obtain powder A.

4. The method for preparing a metal-based toughened multiphase anti-bullet ceramic according to claim 3, characterized in that: The preparation of powder B is to add powder A, B4C powder, SiC powder, TiO2, Si powder and glucose to anhydrous ethanol for wet grinding, with a liquid-to-material volume ratio of 3:1, a ball-to-material ratio of 3:1, a ball mill speed of 200-300 r / min, a ball milling time of 12-15 h, and after drying, pass through a 100-mesh sieve to obtain powder B.

5. The method for preparing a metal-based toughened multiphase anti-bullet ceramic according to claim 4, characterized in that: The powder C is prepared by adding powder B and a toughening agent to anhydrous ethanol for wet grinding, with a liquid-to-material ratio of 1:1, a ball-to-material ratio of 1:1, a ball mill speed of 100-200 r / min, a ball milling time of 20-24 h, and then drying to obtain powder C.

6. A method for preparing a metal-based toughened multiphase anti-bullet ceramic, characterized in that: The steps include: (1) Formula design The ceramic main materials are B4C powder, SiC powder, TiO2, nano carbon black and Si powder, at least three of WB, MoB, CrB and VB constitute toughening agents, glucose and polyvinyl pyrrolidone are sintering aids, and according to mass percentage, B4C powder is 45-70%, SiC powder is 10-15%, TiO2 is 2-5%, nano carbon black is 2-5%, Si powder is 5-10%, metal toughening agent is 5-8%, glucose is 5-10%, and polyvinyl pyrrolidone is 1-5%; (2) Powder preparation Powder A: Add nano-carbon black and polyvinyl pyrrolidone to deionized water at a liquid-to-solid volume ratio of 1:1, perform planetary ball milling at a ball-to-solid ratio of 2:1, a ball milling speed of 300-400 rpm, and a ball milling time of 8-12 hours. Then, dry at 80-100°C for 6-8 hours to obtain powder A. Powder B: Add powder A, B4C powder, SiC powder, TiO2, Si powder and glucose to anhydrous ethanol with a liquid-to-material volume ratio of 3:

1. Perform planetary ball milling with a ball-to-material ratio of 3:1 and a ball milling speed of 200-300 rpm for 12-15 hours. Then dry at 100-120°C for 10-12 hours and pass through a 100-mesh sieve to obtain powder B. Powder C: Powder B and a metal toughening agent were added to anhydrous ethanol at a liquid-to-material volume ratio of 1:

1. The mixture was subjected to planetary ball milling at a ball-to-material ratio of 1:1 at a ball milling speed of 100-200 r / min for 20-24 h. The mixture was then dried at 50-70°C for 8-10 h to obtain powder C. (3) Embryo compression Weigh powder C and place it in a steel mold. Evenly coat the inner wall of the mold with BN to prevent sticking. Apply a pressure of 5±1MPa and maintain it for 6~10h. Then increase the pressure to 15±1MPa and maintain it for 3~5h. Finally, increase the pressure to 30±1MPa and maintain it for 1~2h. (4) Sintering treatment Place the embryo prepared in step (3) in a vacuum sintering furnace, evacuate the furnace and fill it with Ar gas for protection, heat it to 1200±10℃ at 3~5℃ / min, keep it at this temperature and pressure for 50~60min, then heat it to 1850±10℃ at 3~4℃ / min, keep it at this temperature for 40~45min, turn off the heating system, cool it to 50~60℃ with the furnace, turn off the vacuum system and take out the sample.

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