A method for manufacturing a multi-curved surface ballistic panel

Abstract

This invention proposes a method for preparing a multi-curved bulletproof plate, comprising the following steps: S1, mixing diamond, phenolic resin, silicon powder, graphite powder, boron carbide, and silicon carbide in a mixer to obtain a mixture; S2, pressing the mixture into a sample; S3, silicon infiltration firing: modifying and pretreating the silicon particles used for silicon infiltration firing, then performing silicon infiltration firing on the sample, and separating the sample and silicon particles with an alumina plate during silicon infiltration firing. This invention pre-treats silicon particles, causing a thin layer of graphite to adhere to their surface. During the silicon infiltration firing process, the graphite-encased silicon particles first react with the graphite to form a silicon carbide layer. Then, the silicon particles generate silicon vapor, which breaks through the surface silicon carbide layer and reacts with the sample, resulting in a sample surface with only a silicon carbide shell. Surface treatment is easily performed using sandblasting. Furthermore, this invention uses an alumina plate to separate the sample from the silicon block during silicon infiltration firing. The alumina plate is burned off during firing, resulting in almost no silicon residue on the surface of the finished product upon completion.

Description

Technical Field

[0001] This invention relates to the field of bulletproof plate technology, and in particular to a method for preparing a multi-curved bulletproof plate. Background Technology

[0002] Diamond is the hardest known material in the world, while boron carbide (B4C) ceramics are the third hardest natural substance, after diamond and cubic boron nitride. It also possesses properties such as low density, high modulus, and high wear resistance. If a composite of diamond and boron carbide could be achieved, even more ideal armor ceramics could be produced.

[0003] In the 1970s, the United States first prepared reaction-sintered boron carbide ceramic composites using the melt infiltration method, which greatly reduced the preparation cost of boron carbide materials. This method has attracted widespread attention and research from scholars at home and abroad. However, the current mainstream research in China focuses on formulations, with similar processes, leading to the same difficulties: the surface of the obtained samples is difficult to treat or the post-processing time is too long, and even excessive surface deposits can affect actual production and prevent mass production.

[0004] For example, Chinese invention patent published on July 14, 2010, with publication number CN 101774808, discloses a method for preparing a boron carbide double-arc bulletproof plate, including the following steps: (1) Selecting and mixing materials, using boron carbide as raw material, mixing the raw material with the adhesive evenly; (2) Molding, slowly feeding the mixed material into the pressing machine for repeated pressing, and when the mixed material is in sheet form and has a certain toughness, slowly adjusting the gap between the rollers to continue pressing repeatedly to form a breast plate blank, the thickness of the breast plate blank is 3 mm; (3) Sintering, sintering the pressed breast plate blank to obtain the finished product.

[0005] Another Chinese invention patent, published on January 23, 2024, with publication number CN117430424A, discloses a method for preparing composite boron carbide ceramics and its application in bulletproof ceramic inserts. The preparation method includes boron carbide pretreatment, preparation of a mixture, preparation of a slurry, granulation, preparation of a green body, and sintering steps. The boron carbide pretreatment includes plasma treatment and secondary treatment. The preparation of the mixture involves mixing the pretreated boron carbide, sodium aluminum silicate, titanium powder, and modified carbon black. After uniform mixing, the mixture is subjected to pulsed electric field treatment. The pulsed electric field treatment time is controlled to be 8-12 min, the pulsed electric field intensity is 32-36 kV / cm, the pulse frequency is 610-630 Hz, and the pulse width is 40-44 μs. The mixture is obtained after the pulsed treatment.

[0006] The aforementioned patents mainly focus on formula research, but the bulletproof plates produced face problems such as difficult surface treatment of the obtained samples or excessively long post-processing time, and even problems such as excessive surface deposits affecting actual production and use. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention proposes a method for preparing multi-curved bulletproof plates, which solves the problems in the prior art where the surface of bulletproof plates made of boron carbide is difficult to process or the post-processing time is too long, or even the excessive surface deposits affect actual production and use.

[0008] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0009] A method for preparing a multi-curved bulletproof plate includes the following steps:

[0010] S1. Diamond, phenolic resin, silicon powder, graphite powder, boron carbide, and silicon carbide are placed in a mixer and mixed evenly to obtain a mixture.

[0011] S2. Compress the mixture into a sample;

[0012] S3. Silicon infiltration firing: The silicon particles used for silicon infiltration firing are modified and pretreated, and then the sample and silicon particles are separated by an alumina plate for silicon infiltration firing.

[0013] This invention pre-treats silicon particles by immersing them in a solution of graphite (carbon black), a small amount of cellulose, and water, followed by drying. This causes a thin layer of graphite to adhere to the surface of the silicon particles. During the silicon infiltration firing process, the graphite-encased silicon particles first react with the graphite to form a silicon carbide layer. As the temperature continues to rise, the silicon particles inside form silicon vapor and break through the surface silicon carbide layer to react with the sample. After the reaction, the sample surface only has a silicon carbide shell, making surface treatment very easy using sandblasting. This invention also separates the sample from the silicon block using an alumina plate during silicon infiltration firing. Since the firing temperature is approximately between 1550-1650℃, the alumina plate will burn off during firing. Finally, when the firing is complete, there is almost no silicon residue on the surface of the finished product.

[0014] Furthermore, in order to address the issue that the material obtained when using ethanol is only suitable for immediate use and will clump if stored for more than 4 hours, ethylene glycol spray is added during the mixing process in step S1.

[0015] Furthermore, in order to enhance the mixing effect, the mixer is tilted at a specific angle to perform the mixing.

[0016] Furthermore, to enhance the mixing effect, the mixing machine rotates at a speed of 3000-6000 r / min.

[0017] Further, in order to enhance the mixing effect, ethylene glycol spray is added after dry mixing in the mixer for 3 - 15 minutes, and the addition amount each time is 20 - 25% of the solvent.

[0018] Further, in order to avoid the problem that the sample surface appears pitted during pressing and is judged as a non - qualified sample due to easy sticking to the mold, step S2 includes pre - placing a diaphragm in the pressing die cavity and pressing the mixture described in step S1 after placing it in the diaphragm.

[0019] Further, in order to make the diaphragm have better air permeability, the diaphragm includes but is not limited to breathable paper or non - woven fabric, and the thickness is 0.2 - 1.8 mm.

[0020] Further, in order to facilitate the demolding of the sample after pressing, a release agent is coated on the surface of the diaphragm.

[0021] Further, in order to avoid the problem that silicon particles re - attach to the surface of the sample during temperature cooling, making the surface treatment of the finished product difficult, the modification pretreatment of the silicon particles includes soaking the silicon particles in a solution containing graphite, cellulose and water for 8 - 15 minutes, and then drying.

[0022] Further, in order to obtain an alumina plate that can be burned and decomposed during silicon infiltration firing, the production of the alumina plate includes mixing alumina powder, cellulose and water to obtain a dry powder material, and weighing the dry powder material and pressing it into an alumina plate on a sample mold.

[0023] Further, in order to obtain an alumina plate that can be burned and decomposed during silicon infiltration firing, the thickness of the alumina plate is 0 < T ≤ 4 mm, and the pressing pressure is 5 - 50 MPa.

[0024] Further, in order to obtain an alumina plate that can be burned and decomposed during silicon infiltration firing, the alumina powder uses particles with a mesh size of 100 - 3000.

[0025] Further, in order to achieve a better effect of silicon infiltration firing and enable the decomposition of the alumina plate, the temperature of the silicon infiltration firing is 1550 - 1650 °C.

[0026] Advantages of the present invention:

[0027] 1. Considering industrial mass production, the present invention improves the mixing method, changes wet mixing to dry mixing, and avoids uneven mixing and long - term time costs.

[0028] 2. The present invention mixes materials by tilting the mixer at a specific angle. In this way, during the rotation of the mixing disk, the materials are conveyed upward, and when the materials reach a certain height, they fall downward under the action of gravity. Through horizontal and vertical movements, material mixing is formed, and the mixing is more uniform.

[0029] 3. This invention innovatively uses high-boiling-point ethylene glycol, which effectively solves the problem that the material obtained when using ethanol is only suitable for immediate use and will clump if stored for more than 4 hours.

[0030] 4. When ethylene glycol is used as a solvent in this invention, the material obtained by dry mixing is in good condition, without clumping, and can be used normally after 5 days of storage.

[0031] 5. This invention uses a specially treated diaphragm of a certain thickness added during pressing to avoid the problem of samples sticking to the mold during pressing, which can cause pits on the sample surface and lead to the sample being judged as unqualified.

[0032] 6. In this invention, after coating the surface of the diaphragm with graphite, talc powder and a powdered release agent that acts as a lubricant, the excess release agent on the surface is shaken off, and the diaphragm is placed into the mold cavity for pressing. This solves the problems of long hot pressing time and low yield of cold pressing.

[0033] 7. This invention pre-treats silicon particles by immersing them in a solution of graphite (carbon black), a small amount of cellulose, and water, followed by drying. This causes a thin layer of graphite to adhere to the surface of the silicon particles. During the silicon infiltration firing process, the silicon particles encased in graphite react with the graphite to form a silicon carbide layer. As the temperature continues to rise, the silicon particles inside form silicon vapor and break through the surface silicon carbide to react with the sample. After the reaction, the sample surface only has a silicon carbide shell, which is easily treated by sandblasting.

[0034] 8. The present invention uses alumina powder, cellulose and water to mix to obtain alumina powder dry powder, and then presses the dry powder into an alumina plate on a sample mold to make an alumina plate that can be sintered during the silicon infiltration firing process.

[0035] 9. The present invention uses a pressed alumina plate to separate the sample from the silicon block during silicon infiltration firing. Since the firing temperature is about 1550-1650℃, the alumina plate will be burned off during firing. When the firing is finally completed, there is almost no silicon residue on the surface of the finished product.

[0036] 10. This invention effectively solves the difficulty of subsequent sample surface treatment through reform and innovation of the process flow, enabling it to be mass-produced and applied. Detailed Implementation

[0037] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0038] The method for preparing a multi-curved bulletproof plate according to Embodiment 1 of the present invention includes the following steps:

[0039] 1) Diamond, phenolic resin, silicon powder, graphite powder, boron carbide, and silicon carbide of a certain particle size are mixed in a mixer. The mixer consists of a high-speed rotor, a rotating mixing disc, and a multi-functional scraper. The mixer is tilted at a specific angle, and the high-speed rotor is set to a speed of 3000-6000 r / min. An oil pump spray device is installed on the top cover of the mixer. In this invention, the required high-boiling-point ethylene glycol is added to a liquid tank. After dry mixing for 3-15 minutes, the spray device is turned on. The amount added each time is about 20-25% of the solvent. The mixture is obtained by spraying multiple times to ensure uniform mixing. The spray device adopts the structure of existing technology.

[0040] This mixing method uses high-boiling-point ethylene glycol, effectively solving the problem that materials obtained when using ethanol are only suitable for immediate use and will clump after being stored for more than 4 hours. With ethylene glycol as the solvent, the dry-mixed material is in better condition, without clumping, and can be used normally after being stored for 5 days. Furthermore, it solves the problem that the wet mixing process in the existing technology may not only result in uneven mixing but also take a long time, making it only suitable for laboratory tests and not for industrial mass production.

[0041] 2) Press the mixed mixture. Before pressing, add a specially treated diaphragm of a certain thickness into the mold cavity. The diaphragm includes, but is not limited to, paper or non-woven fabric of the same size as the mold, with low carbon residue and good air permeability, and a thickness of 0.2-1.8 mm.

[0042] After coating the surface of the diaphragm (i.e., the aforementioned paper or non-woven fabric) with graphite, talc, or other lubricating powdered release agents, and shaking off excess release agent, the diaphragm is placed into the mold cavity. The mixture is then added to the diaphragm, and pressing is performed to obtain the sample. By adding a diaphragm of a certain thickness during pressing, the problems of long hot-pressing time and low yield in cold-pressing are solved.

[0043] This pressing method solves the problem that the powder particle sizes used in existing cold pressing are relatively small, which easily causes sticking to the mold during pressing. In industrial production, this leads to pits on the surface of the sample, resulting in the sample being judged as unqualified, seriously affecting production efficiency and the yield rate of the sample.

[0044] 3). Then, perform silicon infiltration firing on the sample: Before silicon infiltration firing, pre-treat the silicon particles to modify them. The pre-treatment of the silicon particles includes soaking silicon particles of a certain particle size in a solution composed of graphite (carbon black), a small amount of cellulose, and water for about 8 - 15 minutes, and then drying them, so that a thin layer of graphite adheres to the surface of the silicon particles; and mix alumina powder (100 - 3000 mesh), cellulose, and water to obtain a dry powder of alumina powder. Then, weigh a certain amount of the dry powder and press it into an alumina plate on the sample mold; the thickness of the alumina plate can be 0 < T ≤ 4 mm, and the pressing pressure is 5 - 50 MPa to obtain an alumina plate of the same size as the required fired sample.

[0045] During silicon infiltration firing, separate the sample and the pre-treated modified silicon particles with the pressed alumina plate, and perform silicon infiltration firing to obtain the finished product. Since the firing temperature is between about 1550 - 1650 °C, the alumina plate will be decomposed during firing, and finally, when the firing is completed, there will be almost no silicon residue on the surface of the finished product.

[0046] Moreover, because a thin layer of graphite adheres to the surface of the silicon particles, the silicon particles wrapped by graphite will first react with graphite to form a silicon carbide layer during the firing process. As the temperature continues to rise, the silicon particles inside form silicon vapor, and the vapor pressure gradually increases to reach a critical value, breaking through the surface silicon carbide, and the silicon vapor contacts the sample for reaction. After the reaction ends, only a silicon carbide shell remains on the surface of the sample, and it is very easy to perform surface treatment by means of sandblasting. This avoids the problem in the prior art that no treatment is done to the silicon material during silicon infiltration firing, and the silicon material will reattach to the surface of the sample when the temperature cools, with some showing a large-area average distribution and some showing a large local enrichment, which will cause different thermal expansion coefficients of the sample and cracking, seriously affecting the yield rate and appearance of the sample.

[0047] Example 2

[0048] 1). Place diamond, phenolic resin, silicon powder, graphite powder, boron carbide, silicon carbide, etc. with a certain particle size in a mixer, and the mixer is tilted at a specific angle. Set the rotation speed of the high-speed rotor to 3000 - 6000 r / min; add high-boiling-point ethylene glycol to the liquid tank of the oil pump spray device installed on the mixer. After dry mixing for 3 - 15 minutes, start the spray device, and the addition amount each time is about 20% of the solvent until the mixture is evenly mixed to obtain a mixture.

[0049] 2). Then press the mixture into a sample.

[0050] 3) The sample is subjected to silicon infiltration and firing to obtain the finished product.

[0051] Example 3

[0052] 1) Place diamond, phenolic resin, silicon powder, graphite powder, boron carbide, silicon carbide, etc. of a certain particle size into a mixer and mix them. The mixer is tilted at a specific angle and the speed of the high-speed rotor is set to 3000-6000 r / min. Add high-boiling-point ethylene glycol to the liquid tank of the oil pump spray device installed on the mixer. After dry mixing for 3-15 minutes, turn on the spray device. The amount added each time is about 25% of the solvent, until the mixture is uniform and a mixture is obtained.

[0053] 2) The mixed material is pressed. Before pressing, a specially treated diaphragm of a certain thickness is added to the mold cavity. The diaphragm includes, but is not limited to, paper or non-woven fabric of the same size as the mold, with low carbon residue and good air permeability, and a thickness of 0.2 mm. After coating the surface of the diaphragm (i.e., the paper or non-woven fabric) with graphite, talc, or other powdered release agent that provides lubrication, the excess release agent is shaken off, the diaphragm is placed into the mold cavity, the mixture is then placed into the diaphragm, and finally pressed to obtain the sample.

[0054] 3) The sample is subjected to silicon infiltration and firing to obtain the finished product.

[0055] Example 4

[0056] 1) Place diamond, phenolic resin, silicon powder, graphite powder, boron carbide, silicon carbide, etc. of a certain particle size into a mixer and mix them. The mixer is tilted at a specific angle and the speed of the high-speed rotor is set to 3000-6000 r / min. Add high-boiling-point ethylene glycol to the liquid tank of the oil pump spray device installed on the mixer. After dry mixing for 3-15 minutes, turn on the spray device. The amount added each time is about 22% of the solvent, until the mixture is uniform and a mixture is obtained.

[0057] 2) The mixed material is pressed. Before pressing, a specially treated diaphragm of a certain thickness is added to the mold cavity. The diaphragm includes, but is not limited to, paper or non-woven fabric of the same size as the mold, with low carbon residue and good air permeability, and a thickness of 1.8 mm. After coating the surface of the diaphragm (i.e., the aforementioned paper or non-woven fabric) with graphite, talc, or other powdered release agents that provide lubrication, the excess release agent is shaken off. The diaphragm is then placed into the mold cavity, and the mixture is placed into the diaphragm. After pressing, the sample is obtained.

[0058] 3), Then perform silicon infiltration firing on the sample: Before silicon infiltration firing, pretreat the silicon particles to modify them. The pretreatment of the silicon particles includes soaking silicon particles of a certain particle size in a solution composed of graphite (carbon black), a small amount of cellulose, and water for about 8 - 15 minutes, and then drying them, so that a thin layer of graphite adheres to the surface of the silicon particles; then perform silicon infiltration firing on the modified and pretreated silicon particles and the sample to obtain the finished product.

[0059] Example 5

[0060] 1), Place diamond, phenolic resin, silicon powder, graphite powder, boron carbide, silicon carbide, etc. of a certain particle size in a mixer. The mixer is tilted at a specific angle, and the rotation speed of the high-speed rotor is set at 3000 - 6000 r / min; Add high-boiling-point ethylene glycol to the liquid tank of the oil pump spray device installed on the mixer. After dry mixing for 3 - 15 minutes, start the spray device, and the addition amount each time is about 20% of the solvent until the mixture is evenly mixed to obtain the mixture.

[0061] 2), Press the mixture after mixing. Before pressing, add a diaphragm with a certain thickness that has been specially treated into the mold cavity. The diaphragm includes, but is not limited to, paper or non-woven fabric of the same size as the mold and with less residual carbon and good air permeability, with a thickness of 1.0 mm. After surface coating the diaphragm, that is, the above-mentioned paper or non-woven fabric, with graphite or talcum powder or other powdery mold release agents that play a lubricating role, shake off the excess mold release agent on the surface, then put the diaphragm into the mold cavity, and then put the mixture into the diaphragm, and then press to obtain the sample.

[0062] 3), Then perform silicon infiltration firing on the sample: Before silicon infiltration firing, mix alumina powder (100 - 3000 mesh), cellulose, and water to obtain the dry powder of alumina powder, and then weigh a certain amount of the dry powder and press it into an alumina plate on the sample mold; The thickness of the alumina plate can be 0 < T ≤ 4 mm, and the pressing pressure is 5 - 5 MPa, to obtain an alumina plate of the same size as the required fired sample; During silicon infiltration firing use the pressed alumina plate to separate the sample and the silicon particles for silicon infiltration firing to obtain the finished product.

[0063] Comparative Example 1

[0064] Adopt the conventional preparation method. The wet mixing method is used in the mixing stage, that is, mix phenolic resin and ethanol evenly and then wet mix them evenly with silicon powder, boron carbide (silicon carbide), and diamond of a certain particle size, and then dry and crush or granulate; The pressing method is to use cold pressing to make the sample, and then perform conventional silicon infiltration firing to obtain the finished product.

[0065] The finished products obtained from the above embodiments and comparative examples were inspected. The inspection results, namely the storage time, pressing yield, firing yield, product density, porosity, hardness, and three-point bending strength of the products from different embodiments and comparative examples, are shown in Table 1.

[0066] Table 1

[0067] Storage time (h) Pressing yield Firing yield <![CDATA[Density (g / cm 3 )]]> Porosity Hardness (HRA) Three-point bending strength (MPa) Example 1 120 99-100% ＞95 3.08-3.15 0.27-0.58 90-94 325-380 Example 2 120 99-100% 75-85 3.08-3.26 0.55-0.78 90-94 325-365 Example 3 120 99-100% 75-85 3.08-3.26 0.55-0.78 90-94 325-365 Example 4 120 99-100% ＞90 3.08-3.15 0.27-0.58 90-94 325-380 Example 5 120 99-100% ＞90 3.08-3.15 0.27-0.58 90-94 325-380 Comparative Example 1 ＜3 68-73% ＜75 3.01-3.22 0.85-0.96 89-92 300-350

[0068] As can be seen from the table, the preparation method of Example 1 of the present invention, which involves adding ethylene glycol during dry mixing, adding a diaphragm during pressing, and using modified pretreated silicon particles during silicon infiltration firing, and using an alumina plate to separate the silicon particles from the sample, results in a product with the longest storage time, the highest pressing yield and firing yield, higher product density, lower porosity, and the best hardness and three-point bending strength performance. In other words, the resulting multi-curved bulletproof plate is the best.

[0069] The above description is merely a preferred embodiment of the present invention and is not intended 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 should understand that any modifications to the technical solutions described in the foregoing embodiments, or equivalent substitutions of some or all of the technical features thereof, within the spirit and principles of the present invention, do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A method for preparing a multi-curved bulletproof plate, characterized in that, It includes the following steps: S1. Put diamond, phenolic resin, silicon powder, graphite powder, boron carbide, and silicon carbide into a mixer and mix them evenly to obtain a mixture; S2. Press the mixture into a sample; S3. Silicon infiltration firing: The silicon grains used for silicon infiltration firing are pretreated by modification, and then the sample and the silicon grains are separated by an alumina plate for silicon infiltration firing; the temperature of the silicon infiltration firing is 1550 - 1650 °C; The modification pretreatment of the silicon grains includes soaking the silicon grains in a solution containing graphite, cellulose, and water for 8 - 15 minutes, and then drying them.

2. The method for preparing the multi-curved bulletproof plate according to claim 1, characterized in that: In step S1, ethylene glycol spray is added during the mixing process.

3. The method for preparing the multi-curved bulletproof plate according to claim 1 or 2, characterized in that: Step S2 includes pre - placing a diaphragm in the pressing die cavity and then pressing the mixture described in step S1 after putting it into the diaphragm.

4. The method for preparing the multi-curved bulletproof plate according to claim 3, characterized in that: The diaphragm includes breathable paper or non - woven fabric with a thickness of 0.2 - 1.8 mm.

5. The method for preparing the multi-curved bulletproof plate according to claim 3, characterized in that: The surface of the diaphragm is coated with a mold release agent.

6. The method for preparing the multi-curved bulletproof plate according to claim 1, 2, 4, or 5, characterized in that: The production of the alumina plate includes mixing alumina powder, cellulose, and water to obtain a dry powder material, and weighing the dry powder material and pressing it into an alumina plate on a sample mold.

7. The method for preparing the multi-curved bulletproof plate according to claim 6, characterized in that: The thickness of the alumina plate is 0 < T ≤ 4 mm, and the pressing pressure is 5 - 50 MPa.

8. The method for preparing the multi-curved bulletproof plate according to claim 6, characterized in that: The alumina powder uses particles with a mesh size of 100 - 3000.