High-strength SiC-Si3N4 composite ceramic as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of ceramic bulletproof, and discloses a high-strength SiC-Si3N4 composite ceramic and a preparation method and application thereof.The SiC-Si3N4 composite ceramic is SiC ceramics-interlayer-Si3N4 ceramic, and the SiC-Si3N4 composite ceramic is prepared by adding inorganic components between SiC ceramic and Si3N4 ceramic and conducting hot pressing sintering under the N2 atmosphere at the pressure of 5-20 MPa and the temperature of 1500-1800 DEG C; the inorganic components are Si, graphite, rare earth oxide and Al2O3. The SiC-Si3N4 composite ceramic disclosed by the invention fully combines the advantages of high hardness and high elastic modulus of SiC ceramic and high strength and high toughness of Si3N4 ceramic, so that the bending strength of the SiC-Si3N4 composite ceramic is far higher than that of single-layer SiC ceramic, and the SiC-Si3N4 composite ceramic can be applied to the field of ceramic bulletproof.

Description

Technical Field

[0001] The present invention belongs to the field of ceramic bulletproof, and specifically relates to a high-strength SiC-Si3N4 composite ceramic, a preparation method thereof, and an application thereof. Background Art

[0002] SiC ceramics have advantages such as low density, high hardness, and high elastic modulus, and are widely used in the bulletproof field. Traditional SiC ceramic bulletproof plates are of a single-layer SiC ceramic structure. Due to the low flexural strength and fracture toughness of SiC ceramics, when a bullet penetrates the SiC ceramic bulletproof armor, brittle fragmentation is likely to occur, resulting in low bulletproof performance. Increasing the thickness of the SiC ceramic can effectively improve the bulletproof performance, but increasing the thickness will increase the weight of the bulletproof armor and reduce the combat flexibility of individual soldiers. The flexural strength and fracture toughness of Si3N4 ceramics are much higher than those of SiC ceramics, but the hardness and elastic modulus of Si3N4 ceramics are lower than those of SiC ceramics. If the performance advantages of SiC ceramics and Si3N4 ceramics can be combined to prepare a SiC-Si3N4 double-layer composite ceramic, with the SiC ceramic layer as the bullet-facing surface of the bulletproof plate, using its high hardness and high elastic modulus advantages to consume the kinetic energy of the invading bullet, and using Si3N4 as the crack arrest layer to prevent brittle fragmentation of the ceramic with its high strength and high toughness, the problem of insufficient strength of SiC ceramics can be effectively improved, thereby enhancing the bulletproof performance of the ceramic bulletproof plate. Summary of the Invention

[0003] In order to solve the deficiencies of the above-mentioned prior art, the primary object of the present invention is to provide a high-strength SiC-Si3N4 composite ceramic.

[0004] Another object of the present invention is to provide a preparation method of the above SiC-Si3N4 composite ceramic. This method uses Si, graphite, rare earth oxides, and Al2O3 as the intermediate layer components of the SiC ceramic and the Si3N4 ceramic, and is prepared by hot pressing sintering under N2 atmosphere conditions.

[0005] Another object of the present invention is to provide the application of the above SiC-Si3N4 composite ceramic in the bulletproof field.

[0006] The object of the present invention is achieved by the following technical solutions:

[0007] A high-strength SiC-Si3N4 composite ceramic is a SiC ceramic - intermediate layer - Si3N4 ceramic. The SiC-Si3N4 composite ceramic is prepared by adding an inorganic component between the SiC ceramic and the Si3N4 ceramic, and performing hot pressing sintering at a pressure of 5 - 20 MPa and a temperature of 1500 - 1800 °C under N2 atmosphere; the inorganic component is Si, graphite, rare earth oxides, and Al2O3.

[0008] Preferably, the Vickers hardness of the SiC ceramic is > 23 GPa, the flexural strength is > 400 MPa, and the fracture toughness is > 3.5 MPa·m 1 / 2 ; the Vickers hardness of the Si3N4 ceramic is > 17 GPa, the flexural strength is > 800 MPa, and the fracture toughness is > 7 MPa·m 1 / 2 .

[0009] Preferably, the particle sizes of both Si and graphite are 0.1 - 1 μm, and the particle sizes of both rare earth oxide and Al2O3 are 1 - 3 μm.

[0010] Preferably, the mass ratio of Si, graphite, rare earth oxide, and Al2O3 is (5 - 7):2:(6 - 8):(3 - 7).

[0011] Preferably, the rare earth oxide is Y2O3, Yb2O3, La2O3, or Ce2O3.

[0012] The preparation method of the high-strength SiC-Si3N4 composite ceramic includes the following specific steps:

[0013] S1. Ball-mill and mix Si, graphite, rare earth oxide, and Al2O3 evenly to obtain the intermediate layer raw material;

[0014] S2. Place the intermediate layer raw material between the SiC ceramic and the Si3N4 ceramic, and the thickness of the intermediate layer raw material is 100 - 500 μm;

[0015] S3. Place the SiC ceramic, the intermediate layer raw material, and the Si3N4 ceramic in a graphite mold, and under an N2 atmosphere, hot-press sinter at a pressure of 5 - 20 MPa and a temperature of 1500 - 1800 °C to obtain the SiC-Si3N4 composite ceramic.

[0016] Preferably, in step S1, the medium for ball-milling is Si3N4 balls, the solvent for ball-milling is ethanol, the rotation speed for ball-milling is 200 - 500 r / min, and the time for ball-milling is 5 - 24 h.

[0017] Preferably, in step S3, the time for hot-press sintering is 10 - 60 min.

[0018] The application of the SiC-Si3N4 composite ceramic in the field of ceramic bulletproof.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. The SiC-Si3N4 composite ceramic of the present invention effectively improves the flexural strength compared with the traditional SiC ceramic, enabling the composite ceramic to be applied in the field of ceramic bulletproof.

[0021] 2. The present invention uses hot - press sintering to connect SiC ceramics and Si3N4 ceramics by setting an intermediate layer between them, and prepares SiC - Si3N4 composite ceramics. This SiC - Si3N4 composite ceramic fully combines the advantages of the high hardness and high elastic modulus of SiC ceramics and the high strength and high toughness of Si3N4 ceramics, and its flexural strength is much higher than that of single - layer SiC ceramics. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic structural diagram of the high - strength SiC - Si3N4 composite ceramic of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] The following further describes the present invention in detail with reference to the embodiments, but the embodiments of the present invention are not limited thereto. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in the technical field.

[0024] Example 1

[0025] 1. Place 35wt% Si (particle size 0.5μm), 10wt% graphite (particle size 0.5μm), 40wt% Y2O3 (particle size 1μm), and 15wt% Al2O3 (particle size 1μm) in a planetary ball - milling jar. Use Si3N4 balls as the ball - milling medium and ethanol as the solvent, and ball - mill for 12 h at a rotation speed of 350 r / min for uniform mixing. Remove ethanol by rotary evaporation to obtain the intermediate - layer raw material.

[0026] 2. After mixing evenly, place the above - mentioned intermediate - layer raw material between SiC ceramics and Si3N4 ceramics to form a sandwich structure, and the thickness of the intermediate - layer raw material is 200μm.

[0027] 3. Place SiC ceramics, the intermediate - layer raw material, and Si3N4 ceramics in a graphite mold. Under the condition of N2 atmosphere, at a pressure of 10 MPa, hot - press sinter at 1700 °C for 30 min to obtain the SiC - Si3N4 composite ceramic, and its structure is as Figure 1 shown.

[0028] Example 2

[0029] 1. Place 25wt% Si (particle size 0.5μm), 10wt% graphite (particle size 0.5μm), 40wt% Y2O3 (particle size 1μm), and 25wt% Al2O3 (particle size 1μm) in a planetary ball - milling jar. Use Si3N4 balls as the ball - milling medium and ethanol as the solvent, and ball - mill for 12 h at a rotation speed of 350 r / min for uniform mixing. Remove ethanol by rotary evaporation to obtain the intermediate - layer raw material.

[0030] 2. Place the intermediate layer raw material between the SiC ceramic and the Si3N4 ceramic to form a sandwich structure, and the thickness of the intermediate layer raw material is 200 μm.

[0031] 3. Place the SiC ceramic, the intermediate layer raw material, and the Si3N4 ceramic in a graphite mold. Under the condition of N2 atmosphere, the pressure is 10 MPa, and hot press sintering is carried out at 1700 °C for 30 min to obtain the SiC-Si3N4 composite ceramic, and its structure is as Figure 1 shown.

[0032] Example 3

[0033] 1. Place 25 wt% Si (particle size 0.5 μm), 10 wt% graphite (particle size 0.5 μm), 40 wt% Y2O3 (particle size 1 μm), and 25 wt% Al2O3 (particle size 1 μm) in a planetary ball mill tank. Using Si3N4 balls as the ball milling medium and ethanol as the solvent, ball mill for 12 h at a rotation speed of 350 r / min for uniform mixing, and remove ethanol by rotary evaporation to obtain the intermediate layer raw material.

[0034] 2. Place the above intermediate layer raw material between the SiC ceramic and the Si3N4 ceramic to form a sandwich structure, and the thickness of the intermediate layer raw material is 350 μm.

[0035] 3. Place the SiC ceramic, the intermediate layer raw material, and the Si3N4 ceramic in a graphite mold. Under the condition of N2 atmosphere, the pressure is 10 MPa, and hot press sintering is carried out at 1700 °C for 30 min to obtain the SiC-Si3N4 composite ceramic, and its structure is as Figure 1 shown.

[0036] Comparative Example 1

[0037] 1. Place 92 wt% SiC, 4 wt% Al2O3, and 4 wt% Y2O3 in a planetary ball mill tank for uniform mixing. Using Si3N4 balls as the ball milling medium and ethanol as the solvent, ball mill for 24 h at a rotation speed of 300 r / min for mixing, and remove ethanol by rotary evaporation to obtain a uniformly mixed raw material powder.

[0038] 2. Place the above raw material powder in a graphite mold and sinter it in a hot press furnace. The sintering atmosphere is Ar gas, the pressure is 30 MPa, the sintering temperature is 1900 °C, and the holding time is 60 min to obtain the SiC ceramic.

[0039] Since Si3N4 cannot be directly used as a bulletproof plate because its hardness and elastic modulus are insufficient, the high strength of Si3N4 is used to make up for the deficiencies of SiC bulletproof plates. The SiC ceramics used in Examples 1 to 3 are the same as the SiC ceramics in Comparative Example 1. The flexural strength of the SiC ceramics in Comparative Example 1 is 495 MPa, the flexural strength of the SiC-Si3N4 composite ceramics in Example 1 is 580 MPa, the flexural strength of the SiC-Si3N4 composite ceramics in Example 2 is 630 MPa, and the flexural strength of the SiC-Si3N4 composite ceramics in Example 3 is 670 MPa. The flexural strength of the SiC-Si3N4 composite ceramics in Examples 1 to 3 is between 580 and 670 MPa. It can be seen that the flexural strength of the SiC-Si3N4 composite ceramics of the present invention is higher than that of SiC ceramics and can be applied in the field of ceramic bulletproofing. When a bullet penetrates the bulletproof plate, the SiC ceramic layer in the SiC-Si3N4 composite ceramics has high hardness and high elastic modulus and can be used as the bullet-facing surface to consume the kinetic energy of the bullet penetration. The Si3N4 ceramic layer has high fracture toughness and high strength and can be used as a crack arrest layer to prevent the bulletproof plate from cracking.

[0040] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and shall be included in the protection scope of the present invention.

Claims

1. A high-strength SiC-Si3N4 composite ceramic, characterized in that: The SiC-Si3N4 composite ceramic is SiC ceramic-intermediate layer-Si3N4 ceramic. The SiC-Si3N4 composite ceramic is prepared by adding inorganic components between SiC ceramic and Si3N4 ceramic, and hot pressing and sintering at 1500-1800°C under N2 atmosphere at a pressure of 5-20MPa; the inorganic components are Si, graphite, rare earth oxides and Al2O3.

2. The high-strength SiC-Si3N4 composite ceramic according to claim 1, characterized in that: The SiC ceramic has a Vickers hardness of >23 GPa, a flexural strength of >400 MPa, and a fracture toughness of >3.5 MPa·m 1 / 2 The Si3N4 ceramic has a Vickers hardness of >17 GPa, a flexural strength of >800 MPa, and a fracture toughness of >7 MPa·m 1 / 2 .

3. The high-strength SiC-Si3N4 composite ceramic according to claim 1, characterized in that: The particle sizes of Si and graphite are both 0.1-1 μm, and the particle sizes of rare earth oxide and Al2O3 are both 1-3 μm.

4. The high-strength SiC-Si3N4 composite ceramic according to claim 1, characterized in that: The mass ratio of Si, graphite, rare earth oxide and Al2O3 is (5-7):2:(6-8):(3-7).

5. The high-strength SiC-Si3N4 composite ceramic according to claim 4, characterized in that: The rare earth oxide is Y2O3, Yb2O3, La2O3 or Ce2O3.

6. The method for preparing the high-strength SiC-Si3N4 composite ceramic according to any one of claims 1 to 5, characterized in that: The specific steps include: S1. The Si, graphite, rare earth oxide and Al2O3 are ball-milled and mixed to obtain an intermediate layer raw material; S2. The intermediate layer raw material is placed between the SiC ceramic and the Si3N4 ceramic, and the thickness of the intermediate layer raw material is 100 to 500 μm; S3. Place SiC ceramics, intermediate layer raw materials and Si3N4 ceramics in a graphite mold, and hot-press and sinter them at 1500-1800°C under a N2 atmosphere at a pressure of 5-20 MPa to obtain SiC-Si3N4 composite ceramics.

7. The method for preparing high-strength SiC-Si3N4 composite ceramic according to claim 6, characterized in that: The ball milling medium in step S1 is Si3N4 balls, the ball milling solvent is ethanol, the ball milling speed is 200-500 r / min, and the ball milling time is 5-24 h.

8. The method for preparing high-strength SiC-Si3N4 composite ceramics according to claim 6, characterized in that: The hot pressing sintering time in step S3 is 10 to 60 minutes.

9. Application of the SiC-Si3N4 composite ceramic according to any one of claims 1 to 5 in the field of ceramic bulletproofing.

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