Silicon carbide-based composite material with high conductivity and high toughness as well as preparation method and application of silicon carbide-based composite material

Abstract

The invention belongs to the technical field of composite materials, and particularly relates to a silicon carbide-based composite material with high conductivity and high toughness as well as a preparation method and application of the silicon carbide-based composite material. The silicon carbide-based composite material is composed of a SiC matrix containing an alpha-phase and beta-phase double-phase structure and eutectic high-entropy alloy distributed in a network shape. The two components cooperate with each other, so that not only are high conductivity and high toughness effectively considered, but also the sintering temperature can be reduced, the compactness of the material is improved, and the material performance is comprehensively optimized. According to the invention, beta-SiC powder and eutectic high-entropy alloy powder are adopted as raw materials, and sintering is carried out in a vacuum atmosphere by using a discharge plasma sintering furnace. The preparation method is simple in process and can be realized without complicated equipment or process; meanwhile, the high-temperature structural ceramic material has relatively high practicability, is suitable for other high-temperature structural ceramic materials, and shows a wide application prospect.

Description

Technical Field

[0001] The present invention belongs to the technical field of composite materials, and in particular relates to a silicon carbide-based composite material with high conductivity and high toughness, and a preparation method and application thereof. Background Art

[0002] SiC ceramics not only have high strength, high hardness, wear resistance and corrosion resistance, but also have excellent chemical stability, oxidation resistance and radiation resistance, and are widely used in electronics, aerospace, bulletproof armor and other fields. However, due to the brittleness, high hardness and high resistivity of SiC ceramics, it brings challenges in processing, resulting in high processing difficulty and high cost. Conventional processing methods are difficult to achieve precision processing, especially the manufacture of large-sized or complex-shaped SiC ceramic parts. This is also one of the key problems that need to be solved in its engineering applications.

[0003] In order to improve the machinability of SiC ceramics, on the one hand, the conductivity of SiC ceramics is improved by doping or adding conductive phases, especially when using specific technologies such as electrical discharge machining (EDM). The improved conductivity not only reduces the heat-affected zone during machining, but also reduces the risk of cracks or other thermal damage, which has obvious advantages. On the other hand, improving the density of SiC ceramics can enhance its structural strength and make the microstructure of the material more uniform, thereby reducing the risk of crack propagation during machining; at the same time, dense materials have better mechanical properties and can withstand greater stress, thereby improving the stability and controllability of mechanical processing. In addition, the improvement in toughness further improves the machinability of SiC ceramics in mechanical processing, especially in processes such as turning, milling and grinding.

[0004] Therefore, developing a general strategy with simple process, low cost, strong practicality and easy promotion to achieve the synergistic improvement of the conductivity, density and toughness of SiC ceramics can greatly improve its machinability, especially when combined with high-precision machining technologies such as electrospark machining, showing superior performance, which is of great practical significance for materials with complex shapes and high-precision machining requirements in practical applications. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of existing strategies for regulating the composite functions of SiC ceramics, and to provide a silicon carbide-based composite material with high conductivity and high toughness, and a preparation method and application thereof. The preparation method of the silicon carbide-based composite material can not only further enhance the toughness and density of SiC ceramics on the basis of improving the conductivity, but also effectively reduce the sintering temperature and achieve comprehensive optimization of material properties.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0007] The present invention provides a silicon carbide-based composite material with high conductivity and high toughness, which is composed of a SiC matrix containing a dual-phase structure of α-phase and β-phase and a eutectic high entropy alloy distributed in a network. The two work together to effectively balance high conductivity and high toughness, and can also reduce the sintering temperature, improve the density of the material, and thus achieve comprehensive optimization of material performance.

[0008] Furthermore, the α-phase content in the SiC matrix is ​​controlled between 8% and 15%, and the mass of the eutectic high entropy alloy is 2% to 4% of the mass of SiC.

[0009] The present invention also provides a method for preparing a silicon carbide-based composite material with high conductivity and high toughness, comprising the following steps:

[0010] 1) Accurately weighing β-SiC powder and eutectic high entropy alloy powder, mixing them evenly and fully drying them before loading them into a graphite mold, wherein the eutectic high entropy alloy powder is both a conductive phase and a sintering aid;

[0011] 2) Placing the graphite mold in a spark plasma sintering furnace and sintering it in a vacuum atmosphere, and after demolding, obtaining a eutectic high entropy alloy reinforced silicon carbide-based composite material.

[0012] Furthermore, in step 1), the particle size of the β-SiC powder is 10 to 45 μm.

[0013] Furthermore, in step 1), the eutectic high entropy alloy powder composition is AlCoCrFeNi 2.1 , Hf 0.55 CoCrFeNi 2.1 , Nb 0.74 CoCrFeNi 2.1 、 0.65 CoCrFeNi 2.1 、Zr 0.6 CoCrFeNi 2.1 、CoCrFeNiHf 0.4 、CoCrFeNiNb 0.45 、CoCrFeNiTa 0.4 and CoCrFeNiZr 0.55 At least one of .

[0014] Furthermore, in step 1), the particle size of the eutectic high entropy alloy powder is 0.1 to 5 μm, and the amount used is 2 to 4% of the mass of SiC.

[0015] Furthermore, in step 2), the discharge plasma preparation conditions are: sintering temperature is 1700-1900° C., heating rate is 150-200° C. / min, pressure is 30-50 MPa, and holding time is 5-20 min.

[0016] Furthermore, in step 2), the content of α-SiC phase in the eutectic high entropy alloy reinforced silicon carbide based composite material is controlled between 8% and 15%.

[0017] The present invention also discloses the application of the above silicon carbide-based composite material with high conductivity and high toughness in the preparation of composite materials for aerospace, bulletproof armor, transportation and nuclear energy engineering. As a very important engineering composite material, eutectic high entropy alloy reinforced silicon carbide-based composite material has broad application prospects in the fields of aerospace, bulletproof armor, transportation and nuclear energy.

[0018] The principle of the present invention is as follows: On the one hand, the high-strength phase (such as an intermetallic compound with a BCC or HCP structure) and the high-plasticity phase (such as an FCC phase) in the eutectic high-entropy alloy are used to achieve a balanced advantage in strength and toughness, and the toughness is effectively improved without affecting the strength of the SiC matrix. On the other hand, during the sintering process of SiC ceramics, the liquid phase formed after the eutectic high-entropy alloy is melted can not only form a conductive network in the SiC matrix, but also significantly improve the conductivity of SiC ceramics; it can also be used as a sintering aid to reduce the sintering temperature, and can also effectively reduce the surface energy between particles, promote faster diffusion, rearrangement and bonding of SiC particles at high temperatures, and then improve the density of the material to obtain a more uniform microstructure. In addition, the liquid phase can also promote the transformation of part of β-SiC to α-SiC phase, so that the SiC matrix presents a β and α dual-phase structure, further enhancing its toughness.

[0019] The beneficial effects of the present invention are:

[0020] 1. The eutectic high entropy alloy introduced in the present invention serves as a conductive phase and is distributed in a network-like manner in the SiC matrix, which significantly improves the conductive properties of SiC ceramics.

[0021] 2. The eutectic high entropy alloy introduced in the present invention has both high strength and high toughness, and effectively improves its toughness without affecting the strength of the SiC matrix.

[0022] 3. The molten liquid phase formed by the eutectic high entropy alloy introduced in the present invention during the plasma sintering process is used as a sintering aid, which not only reduces the sintering temperature and improves the density, but also promotes the transformation of β-SiC to α-SiC, further enhancing the toughness of the material.

[0023] 4. The preparation process of the present invention is simple and can be successfully completed without using complicated processes or additional special equipment.

[0024] 5. The preparation method provided by the present invention is highly practical and applicable to other high-temperature structural ceramics and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0026] Figure 1 Example 1 eutectic high entropy alloy AlCoCrFeNi 2.1 XRD spectrum of

[0027] Figure 2 Example 1 eutectic high entropy alloy AlCoCrFeNi 2.1 SEM image of reinforced silicon carbide-based composites. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] The specific embodiments of the present invention are as follows:

[0030] Example 1

[0031] Weigh 8.00 g of β-SiC powder with a particle size of 38.3 μm, eutectic high entropy alloy AlCoCrFeNi with a particle size of 2 μm, and 2.1 0.32g powder; the weighed raw materials are mixed evenly and fully dried, then loaded into a graphite mold and placed in a spark plasma sintering furnace for sintering in a vacuum atmosphere at a sintering temperature of 1900°C, a pressure of 40MPa, and a holding time of 10min. After natural cooling, SiC-4%AlCoCrFeNi 2.1 Composite materials. After testing, the prepared SiC-4%AlCoCrFeNi 2.1 The α-SiC content in the composite material is 8.5%, the relative density is 98.5%, and the electrical conductivity is 8.2×10 4S / m, three-point bending strength is 681MPa, Vickers hardness is 26.3GPa, fracture toughness is 6.2MPa·m 1 / 2 The XRD spectrum and SEM images of the composite material are shown in Figure 1 and Figure 2 As shown. Figure 1 It can be seen that the high entropy alloy powder used has FCC and B2 eutectic structure; Figure 2 It can be seen that the eutectic high entropy alloy AlCoCrFeNi 2.1 A distinct conductive network is formed in the SiC matrix.

[0032] Example 2

[0033] Weigh 8.00 g of β-SiC powder with a particle size of 15.6 μm and 0.6 μm of eutectic high entropy alloy AlCoCrFeNi 2.1 0.24g powder; the weighed raw materials are mixed evenly and fully dried, then loaded into a graphite mold and placed in a spark plasma sintering furnace for sintering in a vacuum atmosphere at a sintering temperature of 1800°C, a pressure of 40MPa, and a holding time of 10min. After natural cooling, SiC-3%AlCoCrFeNi 2.1 Composite materials. After testing, the prepared SiC-3%AlCoCrFeNi 2.1 The α-SiC content in the composite material is 8.1%, the relative density is 99.3%, and the electrical conductivity is 9.1×10 4 S / m, three-point bending strength is 721MPa, Vickers hardness is 29.6GPa, fracture toughness is 6.8MPa·m 1 / 2 It can be seen that in the reduction of eutectic high entropy alloy AlCoCrFeNi 2.1 Under the experimental conditions of reducing the particle size and dosage of the powder and lowering the sintering temperature, SiC-3%AlCoCrFeNi with improved performance can still be prepared. 2.1 Composite materials.

[0034] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to specific implementation methods. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A silicon carbide-based composite material with high conductivity and high toughness, characterized in that: The composite material consists of a SiC matrix containing an alpha phase and a beta phase dual-phase structure and a eutectic high entropy alloy distributed in a network shape.

2. The silicon carbide-based composite material with high conductivity and high toughness according to claim 1, characterized in that: The α phase content in the SiC matrix is ​​controlled between 8% and 15%, and the mass of the eutectic high entropy alloy is 2% to 4% of the mass of SiC.

3. The method for preparing a silicon carbide-based composite material with high conductivity and high toughness according to claim 1 or 2, characterized in that: The steps include: 1) Accurately weighing β-SiC powder and eutectic high entropy alloy powder, mixing them evenly and fully drying them before loading them into a graphite mold, wherein the eutectic high entropy alloy powder is both a conductive phase and a sintering aid; 2) Placing the graphite mold in a spark plasma sintering furnace and sintering it in a vacuum atmosphere, and after demolding, obtaining a eutectic high entropy alloy reinforced silicon carbide-based composite material.

4. The preparation method according to claim 3, characterized in that: In step 1), the particle size of the β-SiC powder is 10 to 45 μm.

5. The preparation method according to claim 3, characterized in that: In step 1), the eutectic high entropy alloy powder composition is AlCoCrFeNi 2.1 , Hf 0.55 CoCrFeNi 2.1 , Nb 0.74 CoCrFeNi 2.1 、 0.65 CoCrFeNi 2.1 、Zr 0.6 CoCrFeNi 2.1 、CoCrFeNiHf 0.4 、CoCrFeNiNb 0.45 、CoCrFeNiTa 0.4 and CoCrFeNiZr 0.55 At least one of .

6. The preparation method according to claim 3, characterized in that: In step 1), the particle size of the eutectic high entropy alloy powder is 0.1 to 5 μm, and the amount used is 2 to 4% of the mass of SiC.

7. The preparation method according to claim 3, characterized in that: In step 2), the discharge plasma preparation conditions are: sintering temperature is 1700-1900° C., heating rate is 150-200° C. / min, pressure is 30-50 MPa, and holding time is 5-20 min.

8. The preparation method according to claim 3, characterized in that: In step 2), the content of α-SiC phase in the eutectic high entropy alloy reinforced silicon carbide based composite material is controlled between 8% and 15%.

9. Use of a silicon carbide-based composite material with high conductivity and high toughness according to claim 1 or 2 in the preparation of composite materials for aerospace, bulletproof armor, transportation and nuclear energy engineering.

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