Boron carbide-based biomimetic laminated ceramic material and method of making the same

Abstract

The application relates to a preparation method of a boron carbide-based biomimetic laminated ceramic material, which comprises the following steps: S1, mixing boron carbide powder, titanium carbide powder and boron powder with anhydrous ethanol as a medium, sieving and granulating the mixed slurry after rotary evaporation and drying in a vacuum drying box to obtain A, B ternary mixed powder; S2, sequentially laying and loading the A, B ternary mixed powder into a graphite mold to form an "A-B-A" type three-layer structure, and preparing the boron carbide-based biomimetic laminated ceramic material by high-temperature pressure sintering under vacuum conditions. The application utilizes the energy released by in-situ synthesis reaction and the high-activity generated product to promote densification and refine the grain size; meanwhile, the biomimetic laminated structure is adopted to provide an additional strengthening mechanism for the ceramic, solves the problem that the bending strength, hardness and fracture toughness of the boron carbide-based ceramic cannot be synergistically increased, the production process is simple, the preparation cost is low, the mechanical properties of the boron carbide ceramic are improved, and the obtained product simultaneously has the characteristics of low density, high strength and high hardness.

Description

Technical Field

[0001] This invention relates to lightweight ceramic materials and their applications, and more specifically, to a boron carbide-based biomimetic multilayer ceramic material and its preparation method. Background Technology

[0002] Boride ceramics are an important class of engineering materials. Due to their unique physicochemical properties (such as high hardness, high modulus, low specific gravity, excellent high-temperature resistance, and electrical conductivity), they hold significant application prospects in modern high-tech industries. In the past decade, research on boronide ceramic materials has attracted considerable attention both domestically and internationally. One of the key research issues is how to further improve the mechanical properties of boron carbide ceramics while maintaining low specific gravity. Numerous studies have shown that refining the grain size of ceramic materials to prepare ultrafine-grained ceramics can effectively improve the strength and toughness of the material. Second-phase strengthening technology is also a technical approach to improve ceramic materials. However, the preparation of boron carbide nanopowder is very difficult, and rapid grain growth is inevitable during high-temperature sintering. Therefore, preparing high-strength, high-toughness, ultrafine-grained boron carbide ceramics remains a challenge. In recent years, scientists have studied the multi-level layered structure of nacre in natural shells and, through biomimetic structural design, have developed the preparation and research of layered ceramic structures. Layered ceramics are designed based on energy dissipation mechanisms. Through rational layering design, the sensitivity of material mechanical properties to defects is reduced, thereby improving ceramic toughness. Compared to bulk ceramics, cracks in layered ceramics have longer propagation paths, thus improving fracture toughness. Simultaneously, due to the mismatch in thermal expansion coefficients of each layer, residual stress is generated at the interface in layered ceramics, and appropriate residual stress can also have a beneficial effect on mechanical properties. Therefore, layered structures significantly improve the mechanical properties of ceramics. Current research shows that layered structures can capture and deflect major cracks, resulting in significantly higher fracture toughness than bulk ceramics, and layered ceramics exhibit lower sensitivity to defects and damage. Layered structures hold broad research potential for improving the mechanical properties of boron carbide-based ceramics. In terms of dispersion strengthening and toughening technology, research has found that among various boron carbide ceramic reinforcing phase candidates, titanium boride is the most promising reinforcing phase. It possesses high hardness, high modulus, and low specific gravity, making it an ideal reinforcement for lightweight boron carbide ceramic composites.

[0003] Densification of boron carbide ceramics is extremely difficult. Generally, it involves mixing ceramic powders and then sintering at high temperature and pressure. However, this method results in high sintering temperatures and unsatisfactory microstructure and properties. Research indicates that in-situ reaction synthesis can not only produce boron carbide composite ceramics with ultrafine grain structures but also achieve uniform microstructure and refined grains, potentially leading to superior performance.

[0004] In-situ synthesis generally utilizes chemical reactions to synthesize materials. Related research indicates that in the in-situ synthesis system of boron carbide-titanium boride composite ceramics, the chemical reaction between titanium carbide and boron can effectively yield boron carbide-titanium boride composite ceramics. However, in this synthesis system, the component ratio of the boron carbide-titanium boride composite ceramics is generally determined based on the chemical reaction equation, making it difficult to control within a large range. The boron carbide content is generally no more than 45 wt%, which leads to a significant increase in the specific gravity of the boron carbide composite ceramic, resulting in the loss of the lightweight ceramic characteristics of boron carbide ceramics and a decrease in its hardness. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a boron carbide-based biomimetic multilayer ceramic material and its preparation method. The process is simple, the layers are well bonded, the microstructure and interface structure can be well controlled, the grains can be refined, and a boron carbide-based biomimetic multilayer ceramic composite material with low specific gravity, good strength and toughness can be prepared.

[0006] The technical solution adopted by this invention to solve its technical problem is: a method for preparing a boron carbide-based biomimetic multilayer ceramic material, comprising the following steps:

[0007] S1. Boron carbide powder, titanium carbide powder and boron powder are mixed with anhydrous ethanol as a medium. After the mixture is dried in a vacuum drying oven by rotary evaporation, it is sieved and granulated to obtain ternary mixed powder of A and B.

[0008] S2. The ternary mixed powders A and B are sequentially laid into a graphite mold to form an "ABA" type three-layer structure. Boron carbide-based biomimetic multilayer ceramic material is prepared by high-temperature and pressure sintering under vacuum conditions.

[0009] According to the above scheme, the boron carbide powder has a particle size of 2-8 μm and a purity greater than 97%; the titanium carbide powder has a particle size of 2-4 μm and a purity greater than 99%; the boron powder has a particle size of 1-3 μm and a purity greater than 95%; the raw material powder mixture of boron carbide powder, titanium carbide powder and boron powder, by weight percentage, includes 55.14wt%-82.03wt% boron carbide powder, 8.60wt%-21.56wt% titanium carbide powder, and 9.36wt%-23.30wt% boron powder.

[0010] According to the above scheme, in the "ABA" type three-layer structure, the outer layer thickness after sintering and processing is about 0.75mm, and the middle layer thickness is 1.5mm.

[0011] According to the above scheme, in step S1, boron carbide powder, titanium carbide powder and boron powder are processed by a planetary ball mill with a rotation speed of 200-300 r / min.

[0012] According to the above scheme, in step S1, the temperature of the vacuum drying oven is 60-100℃, and the drying time is 24-48h.

[0013] According to the above scheme, in step S1, the sieve is 100-325 mesh.

[0014] According to the above scheme, in step S2, the vacuum condition is better than 20 Pa.

[0015] According to the above scheme, in step S2, the high-temperature pressure sintering method is as follows: The temperature is increased to 1400℃ at a heating rate of 10-15℃ / min under a pressure of 10MPa, and then increased to 1950-2000℃ at a heating rate of 10-15℃ / min, while the pressure is increased to 30MPa. Sintering is carried out at this temperature and pressure for 30-60 minutes, followed by natural cooling.

[0016] The present invention also provides a boron carbide-based biomimetic multilayer ceramic material, which is prepared by a method for preparing boron carbide-based biomimetic multilayer ceramic materials.

[0017] According to the above scheme, the bulk density of the boron carbide-based multilayer ceramic prepared is 2.638 g / cm³. 3 It has a flexural strength of 826 MPa, a hardness of 38.43 GPa, and a fracture toughness of 7.93 MPa·m. 1 / 2 .

[0018] The boron carbide-based biomimetic multilayer ceramic material and its preparation method according to the present invention have the following beneficial effects:

[0019] 1. This invention uses in-situ reaction sintering technology to prepare boron carbide-titanium boride composite material using boron carbide, titanium carbide powder and boron powder as raw materials. It solves the problems of low boron carbide content, high material specific gravity and reduced hardness in in-situ composite boron carbide ceramics, as well as the key technology of preparation where it is difficult to uniformly mix and disperse ultrafine powders. The sintered multiphase ceramic has the advantages of fine grains and high density.

[0020] 2. This invention biomimetically designs an "ABA"-type three-layer laminated ceramic structure. Each layer has good interfacial bonding, providing an additional strengthening and toughening mechanism for boron carbide ceramics. While maintaining the low density of boron carbide-based ceramics, it synergistically increases flexural strength, hardness, and fracture toughness, achieving excellent comprehensive mechanical properties. Under optimal processing conditions, the bulk density is 2.638 g / cm³. 3 It has a flexural strength of 826 MPa, a hardness of 38.16 GPa, and a fracture toughness of 7.93 MPa·m. 1 / 2 .

[0021] 3. This invention adopts the principle of in-situ synthesis technology and develops boron carbide-titanium boride three-layer composite ceramic materials through biomimetic structural design to improve the comprehensive performance and application range of boron carbide ceramics. The research results have important application value in the fields of wear-resistant ceramic parts and impact-resistant protective materials. The raw materials used are readily available, the preparation process is simple, the preparation cost is low, the product is easy to process, and it is suitable for large-scale production.

[0022] 4. This invention fully utilizes the energy released by the in-situ synthesis reaction between titanium carbide and elemental boron and the highly active generated products to promote densification and refine grain size. At the same time, it adopts a biomimetic layered structure design to provide an additional strengthening mechanism for ceramics, solving the problem that the bending strength, hardness and fracture toughness of boron carbide-based ceramics cannot grow in a coordinated manner, further improving the mechanical properties of boron carbide ceramics. The resulting product has the characteristics of low density, high strength and high hardness.

[0023] 5. In order to control the boron carbide content within a wide range while meeting the requirements of interlayer bonding in multilayer ceramics, this invention, based on fully utilizing the advantages of in-situ synthesis of boron-titanium carbide, adds ultrafine boron carbide raw materials to the synthesis system to control the boron carbide content, achieving arbitrary control of the boron carbide content between 75-90 wt%. While ensuring the high hardness and low specific gravity of boron carbide composite ceramic materials, it improves the mechanical properties of the materials and reduces the sintering preparation temperature. Attached Figure Description

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0025] Figure 1 This is a schematic diagram of the boron carbide-based biomimetic multilayer ceramic structure in Embodiments 1 and 2 of the present invention;

[0026] Figure 2 This is a cross-sectional SEM image of the boron carbide-based biomimetic laminated ceramic in Example 1 of the present invention;

[0027] Figure 3 The image shows the XRD pattern of the boron carbide-based biomimetic multilayer ceramic in Example 1 of this invention.

[0028] Figure 4 The image shows the XRD pattern of the boron carbide-based biomimetic multilayer ceramic in Example 2 of this invention.

[0029] Figure 5 The image shows the XRD pattern of the boron carbide-based monolayer ceramic in the comparative example of this invention.

[0030] Figure 6 This is a cross-sectional SEM image of the first layer of the boron carbide-based biomimetic multilayer ceramic in Embodiment 1 of the present invention;

[0031] Figure 7This is a cross-sectional SEM image of the second layer of the boron carbide-based biomimetic laminated ceramic in Embodiment 1 of the present invention;

[0032] Figure 8 This is a cross-sectional SEM image of the third layer of the boron carbide-based biomimetic laminated ceramic in Embodiment 1 of the present invention;

[0033] Figure 9 This is a cross-sectional SEM image of the first layer of the boron carbide-based biomimetic multilayer ceramic after etching in Example 1 of the present invention. Detailed Implementation

[0034] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0035] Example 1

[0036] A method for preparing boron carbide-based biomimetic multilayer ceramics includes the following steps:

[0037] Step 1: Weigh out 82.03 wt% boron carbide powder, 8.60 wt% titanium carbide powder, and 9.37 wt% boron powder to form mixture A; weigh out 73.07 wt% boron carbide powder with an average particle size of 2 μm, 12.90 wt% titanium carbide powder, and 14.03 wt% boron powder to form mixture B. Mixture A and mixture B are mixed separately in anhydrous ethanol using a planetary ball mill at 250 r / min for 2 h, followed by rotary evaporation to obtain slurries A and B. Slurries A and B are dried in a vacuum drying oven at 60℃ for 24 h, then ground and granulated through a 200-mesh sieve to obtain raw material powder mixtures A and B.

[0038] Step 2: Place the raw material powder mixtures A and B into a graphite mold in the following order: first layer of powder A, second layer of powder B, and third layer of powder A. Then, place the mold in a vacuum pressure sintering furnace for vacuum sintering. Maintain a vacuum level better than 20 Pa. Heat the mold to 1400℃ at a rate of 10℃ / min under 10 MPa pressure, then further heat to the maximum temperature of 1950-2000℃ at a rate of 10℃ / min, while simultaneously increasing the pressure to 30 MPa. Hold the mold at this temperature and pressure for 30 minutes, then allow it to cool naturally to obtain a dense boron carbide-based multilayer ceramic material.

[0039] XRD test results are as follows Figure 3 As shown, the results indicate that the product contains only two phases, B4C and TiB2, demonstrating that the raw materials TiC and B react completely during sintering to form B4C and TiB2, with no other impurities present. This proves that the reaction sintering method used in this invention is feasible and can yield sintered materials with the desired composition. SEM results are shown below. Figure 2 ,6 As shown in Figures 7 and 8, the results indicate that the laminated material possesses good interfacial bonding and a clear interfacial structure. White TiB2 is uniformly distributed within the black B4C matrix. The grain size of TiB2 is approximately 2-4 μm, while the grain size of B4C is approximately 1-3 μm. The boron carbide-based laminated ceramic prepared in Example 1 has a bulk density of 2.638 g / cm³. 3 It has a flexural strength of 826 MPa, a hardness of 38.16 GPa, and a fracture toughness of 7.93 MPa·m. 1 / 2 .

[0040] Example 2

[0041] A method for preparing boron carbide-based biomimetic multilayer ceramics includes the following steps:

[0042] Step 1: Weigh out 73.07 wt% boron carbide powder, 12.90 wt% titanium carbide powder, and 14.03 wt% boron powder to form mixture A; weigh out 64.11 wt% boron carbide powder with an average particle size of 2 μm, 17.22 wt% titanium carbide powder, and 18.67 wt% boron powder to form mixture B. Mixture A and mixture B are mixed separately in anhydrous ethanol using a planetary ball mill at 250 r / min for 2 h, followed by rotary evaporation to obtain slurries A and B. Slurries A and B are dried in a vacuum drying oven at 60℃ for 24 h, then ground and granulated through a 200-mesh sieve to obtain raw material powder mixtures A and B.

[0043] Step 2: Place the raw material powder mixtures A and B into a graphite mold in the following order: first layer of powder A, second layer of powder B, and third layer of powder A. Then, place the mold in a vacuum pressure sintering furnace for vacuum sintering. Maintain a vacuum level better than 20 Pa. Heat the mold to 1400℃ at a rate of 10℃ / min under 10 MPa pressure, then further heat to the maximum temperature of 1950-2000℃ at a rate of 10℃ / min, while simultaneously increasing the pressure to 30 MPa. Hold the mold at this temperature and pressure for 30 minutes, then allow it to cool naturally to obtain a dense boron carbide-based multilayer ceramic material.

[0044] XRD test results are as follows Figure 4 As shown, the results indicate that the product contains only two phases: B4C and TiB2. The bulk density of the boron carbide-based multilayer ceramic prepared in Example 2 is 2.713 g / cm³. 3 Flexural strength 753.5 MPa, hardness 37.92 GPa, fracture toughness 8.11 MPa·m 1 / 2 .

[0045] Comparative Example

[0046] A method for preparing boron carbide-based monolayer ceramics includes the following steps:

[0047] Step 1: Weigh out 82.03 wt% boron carbide powder, 8.60 wt% titanium carbide powder, and 9.37 wt% boron powder to form a mixture. Mix the mixture in anhydrous ethanol using a planetary ball mill at 250 rpm for 2 hours, then rotary evaporate to obtain a slurry. Dry the slurry in a vacuum drying oven at 60℃ for 24 hours, then grind and granulate through a 200-mesh sieve to obtain the raw material powder mixture.

[0048] Step 2: Place the raw material powder mixture into graphite molds, then place them in a vacuum pressure sintering furnace for vacuum sintering. Maintain a vacuum level better than 20 Pa. Heat to 1400℃ at a rate of 10℃ / min under 10 MPa pressure, then further heat to the maximum temperature of 1950℃ at a rate of 10℃ / min, while simultaneously increasing the pressure to 30 MPa. Hold the temperature and pressure for 30 minutes, then allow to cool naturally to obtain a dense boron carbide-based multilayer ceramic material.

[0049] XRD test results are as follows Figure 5 As shown, the results indicate that the product contains only two phases: B4C and TiB2. The properties of the prepared boron carbide-based composite ceramic are as follows: bulk density 2.706 g / cm³. 3 The flexural strength is 741.8 MPa, the hardness is 34.63 GPa, and the fracture toughness is 6.05 MPa·m. 1 / 2 .

[0050] Table 1. Density and mechanical properties of ceramics in Examples 1, 2 and Comparative Examples.

[0051]

[0052] In summary, the boron carbide-based multilayer ceramics prepared through biomimetic structural design exhibit a clear interface structure and good interfacial bonding, presenting an "ABA"-type three-layer structure. Furthermore, by employing in-situ reaction sintering technology, TiB2 is uniformly distributed within the B4C matrix in the multilayer ceramics, resulting in tightly bonded and finely grained materials. Compared to the monolayer ceramics in the comparative example, the flexural strength of the multilayer ceramics in Example 1 increased from 741.8 MPa to 826 MPa, the hardness increased from 34.63 GPa to 38.16 GPa, and the fracture toughness increased from 6.05 MPa·m1 / 2 to 7.93 MPa·m1 / 2. Compared to the monolayer ceramics in the comparative example, the multilayer structure significantly improves flexural strength, hardness, and fracture toughness while maintaining a lower density. This invention provides a new method for preparing boron carbide-based ceramics with high strength and high toughness. The prepared boron carbide-based multilayer ceramic composite material is expected to be applied in fields such as wear-resistant ceramic components and impact-resistant protective materials.

[0053] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A method for preparing a boron carbide-based biomimetic multilayer ceramic material, characterized in that, Includes the following steps: S1. Boron carbide powder, titanium carbide powder and boron powder are mixed with anhydrous ethanol as a medium. After the mixture is dried in a vacuum drying oven by rotary evaporation, it is sieved and granulated to obtain ternary mixed powder of A and B. S2. The ternary mixed powders A and B are sequentially laid into a graphite mold to form an "ABA" type three-layer structure. Boron carbide-based biomimetic multilayer ceramic material is prepared by high-temperature and pressure sintering under vacuum conditions. The raw material powder mixture of boron carbide powder, titanium carbide powder, and boron powder comprises, by weight percentage, 64.11wt%-82.03wt% boron carbide powder, 8.60wt%-17.22wt% titanium carbide powder, and 9.37wt%-18.67wt% boron powder; and in powder B, the titanium carbide powder content is 4.3-4.32wt% higher than that in powder A, and the boron powder content is 4.64-4.66wt% higher.

2. The method for preparing boron carbide-based biomimetic multilayer ceramic material according to claim 1, characterized in that, The boron carbide powder has a particle size of 2-8 μm and a purity greater than 97%; the titanium carbide powder has a particle size of 2-4 μm and a purity greater than 99%; and the boron powder has a particle size of 1-3 μm and a purity greater than 95%.

3. The method for preparing boron carbide-based biomimetic multilayer ceramic material according to claim 1, characterized in that, In the "ABA" type three-layer structure, the outer layer thickness after sintering and processing is 0.75mm, and the middle layer thickness is 1.5mm.

4. The method for preparing boron carbide-based biomimetic multilayer ceramic material according to claim 1, characterized in that, In step S1, boron carbide powder, titanium carbide powder and boron powder are mixed using a planetary ball mill with a rotation speed of 200-300 r / min.

5. The method for preparing boron carbide-based biomimetic multilayer ceramic material according to claim 1, characterized in that, In step S1, the temperature of the vacuum drying oven is 60-100℃, and the drying time is 24-48h.

6. The method for preparing boron carbide-based biomimetic multilayer ceramic material according to claim 1, characterized in that, In step S1, the sieve is 100-325 mesh.

7. The method for preparing boron carbide-based biomimetic multilayer ceramic material according to claim 1, characterized in that, In step S2, the vacuum condition is better than 20 Pa.

8. The method for preparing boron carbide-based biomimetic multilayer ceramic material according to claim 1, characterized in that, In step S2, the high-temperature pressure sintering method is as follows: under a pressure of 10 MPa, the temperature is increased to 1400°C at a heating rate of 10-15°C / min, and then increased to 1950-2000°C at a heating rate of 10-15°C / min, while the pressure is increased to 30 MPa; the temperature and pressure are maintained for sintering for 30-60 minutes, and then the temperature is naturally cooled.

9. A boron carbide-based biomimetic multilayer ceramic material, characterized in that, It is prepared by the method for preparing boron carbide-based biomimetic multilayer ceramic material according to any one of claims 1-7.

10. A boron carbide-based biomimetic multilayer ceramic material according to claim 9, characterized in that, The prepared boron carbide-based multilayer ceramic has a bulk density of 2.638 g / cm³. 3 It has a flexural strength of 826 MPa, a hardness of 38.43 GPa, and a fracture toughness of 7.93 MPa·m. 1 / 2 .

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