Zinc-aluminum oxide doped silicon carbide conductive composite material and preparation method thereof

Abstract

The application provides a zinc-aluminum oxide doped silicon carbide conductive composite material and a preparation method thereof, and belongs to the technical field of ceramic products. The zinc-aluminum oxide doped silicon carbide conductive composite material comprises the following raw materials in parts by weight: SiC 40-80 parts, zinc-aluminum oxide powder 20-60 parts and sintering aid 2-10 parts. The application takes silicon carbide (SiC) as a main raw material, matches with appropriate zinc-aluminum oxide powder, and selects a suitable sintering aid to prepare a silicon carbide composite material, and the conductivity and oxidation resistance of the composite material are both significantly improved compared with silicon carbide ceramics.

Description

Technical Field

[0001] This invention belongs to the field of ceramic products technology, specifically relating to a zinc oxide aluminum doped silicon carbide conductive composite material and its preparation method. Background Technology

[0002] Silicon carbide (SiC) is a typical binary compound semiconductor material with a crystal structure similar to the tetrahedral structure of diamond. In SiC crystals, Si and C atoms intersect through sp... 3 Silicon carbide (SiC) possesses high hardness and strength due to the sharing of electron pairs on its hybrid orbitals, forming very strong tetrahedral covalent bonds. Furthermore, SiC exhibits advantages such as chemical stability, high thermal conductivity, good wear resistance, and a low coefficient of thermal expansion, making it promising for applications in high-tech fields such as semiconductors, nuclear energy, defense, and space technology. However, SiC's high resistivity, high hardness, and low diffusion coefficient make sintering and densification difficult, as well as the processing of complex shapes challenging. It is also prone to oxidation at high temperatures, forming a SiO2 film on its surface, which further affects its conductivity. Therefore, improving the conductivity and oxidation resistance of SiC remains a key focus for researchers.

[0003] To improve the conductivity of SiC, researchers have primarily focused on the controlled addition of impurities or dopants. The conductivity of SiC changes depending on the type of impurity added. Adding impurities or dopants mainly improves conductivity by forming a percolating conductive network within the SiC ceramic. However, the addition of impurities and dopants usually leads to an increase in lattice defects in SiC, affecting its strength, hardness, fracture toughness, and other physical properties. Regarding the oxidation resistance of SiC, a dense, oxidation-resistant coating is typically formed on the surface of the SiC ceramic. However, the presence of this coating often affects the conductivity of the SiC ceramic.

[0004] Patent document CN 112794717 A discloses a high-performance ceramic material with strong conductivity, characterized by comprising the following raw materials in parts by weight: 20-30 parts zirconium oxide, 80-120 parts silicon carbide, 8-16 parts alumina, 10-25 parts zinc powder, 2-4 parts yttrium oxide, 20-40 parts sintering aid, and 30-60 parts polyvinyl alcohol. Its preparation method includes the following specific steps: (1) mixing zirconium oxide and silicon carbide in a certain proportion to form a mixture; (2) adding anhydrous ethanol at a volume ratio of 1:1 to the mixture to form a wet material, and grinding the wet material in a ceramic ball mill for 1.5-3 hours; (3) placing the mixture in a calcining furnace for a first high-temperature calcination; (4) adjusting the temperature, introducing nitrogen gas, and performing a second high-temperature calcination; (5) maintaining a constant temperature, introducing a pulsed current into the mixture for a third high-temperature calcination, with a current magnitude of 1 kA and a period of 0.08 kA. S; (6) After high-temperature calcination, zinc powder is added, and the mixture is placed in a ceramic ball mill for secondary ball milling; (7) Alumina and yttrium oxide are immersed in three times their volume of polyvinyl alcohol to obtain a sintering aid; (8) The sintering aid is added to the mixture after secondary ball milling, and liquid-phase sintering is carried out, with the sintering temperature maintained at 930-1100℃; (9) After sintering, a gradient temperature rapid cooling method is performed to obtain the finished product. The preparation method of this invention is cumbersome, the conductivity of the prepared ceramic material is only slightly improved, and it does not involve antioxidant properties. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a zinc-aluminum oxide-doped silicon carbide conductive composite material that improves the conductivity and oxidation resistance of the material, in order to address the shortcomings of the prior art.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a zinc aluminum oxide doped silicon carbide conductive composite material, comprising the following raw materials in parts by weight: 40-80 parts of SiC, 20-60 parts of zinc aluminum oxide powder, and 2-10 parts of sintering aid.

[0007] Optionally, the zinc oxide aluminum powder is zinc oxide doped with 1-5% aluminum oxide by mass.

[0008] Optionally, the sintering aid is one or a combination of two or more of Y2O3, MgO and TiO2.

[0009] Optionally, the zinc oxide aluminum doped silicon carbide conductive composite material further includes: a binder, wherein the binder is present in 2-10 parts by weight.

[0010] Optionally, the adhesive is an alcohol solution or aqueous solution of one or more of polyvinyl alcohol, phenolic resin and polyvinylpyrrolidone.

[0011] Optionally, the zinc-aluminum oxide-doped silicon carbide conductive composite material is composed of the following raw materials in parts by weight: 40-80 parts SiC, 20-60 parts zinc-aluminum oxide powder, 2-10 parts sintering aid, and 2-10 parts binder.

[0012] Preferably, the zinc-aluminum oxide-doped silicon carbide conductive composite material is composed of the following raw materials in parts by weight: 60-75 parts SiC, 25-40 parts zinc-aluminum oxide powder, 5-8 parts sintering aid, and 4-8 parts binder.

[0013] The present invention also provides a method for preparing the above-mentioned zinc oxide aluminum doped silicon carbide conductive composite material, comprising the following steps:

[0014] S01: Provide SiC, zinc-aluminum oxide powder (first part), and sintering aids, add ethanol solution, stir, ball mill, mix evenly to obtain slurry;

[0015] S02: The slurry is dried in a vacuum drying oven, a binder is added, it is formed by isostatic pressing, and then dried in a vacuum drying oven to obtain a ceramic green body;

[0016] S03: The second part of zinc-aluminum oxide powder is used to prepare a surface coating of ceramic green body to obtain a composite green body;

[0017] S04: The composite green body is sintered in an air atmosphere, heated to 600-800℃ in an oxidation furnace at 5-10℃ / min and held for 2-4 h, then heated to 900-1100℃ at 4-6℃ / min and held for 1-3 h, and finally heated to 1200-1400℃ at 1-3℃ / min and held for 1-3 h. The sintered green body is cooled with the furnace to obtain the composite ceramic.

[0018] Optionally, the mass ratio of the first part of zinc-aluminum oxide powder to the second part of zinc-aluminum oxide powder is 1:(0.5~1).

[0019] Optionally, the ball mill is a planetary ball mill, running unidirectionally for 1 to 3 hours at a speed of 200 to 400 r / min.

[0020] Optionally, the isostatic pressing pressure is 100~200 MPa.

[0021] Optionally, the surface coating can be prepared by one of the following methods: high-temperature firing after brushing, high-temperature firing after vacuum impregnation, plasma spraying, and flame spraying.

[0022] Optionally, the thickness of the coating is 10~300 μm.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] This invention uses silicon carbide (SiC) as the main raw material, combined with an appropriate amount of zinc oxide aluminum powder, and selects suitable sintering aids to prepare silicon carbide composite materials. The electrical conductivity and oxidation resistance of the composite material are significantly improved compared with silicon carbide ceramics, while the mechanical properties of the composite material do not deteriorate.

[0025] This invention first mixes SiC, zinc-aluminum oxide powder, and sintering aids to form a slurry, dries it, adds a binder, shapes it, dries it again, and forms a ceramic green body. Then, a second portion of zinc-aluminum oxide powder is used to prepare a surface coating on the ceramic green body, resulting in a composite green body. Finally, the composite green body is sintered in air at a gradient temperature to obtain a composite ceramic. It can be seen that, on the one hand, this invention mixes zinc-aluminum oxide powder with raw materials such as silicon carbide. During high-temperature sintering, the introduced zinc-aluminum oxide particles fill the ceramic voids after melting at high temperatures. Combined with the sintering aids, this lowers the firing temperature of the ceramic and optimizes the network structure of the silicon carbide ceramic, improving its density and conductivity. On the other hand, this invention prepares a zinc-aluminum oxide coating on the surface of the ceramic green body. Experiments have shown that this coating can prevent the oxidation of ceramic materials at high temperatures, improving the oxidation resistance of silicon carbide ceramics at high temperatures. Simultaneously, the zinc-aluminum oxide coating also enhances the conductivity of the material.

[0026] This invention optimizes the raw material composition of silicon carbide ceramic materials and combines it with a scientific preparation method, thereby significantly improving the electrical conductivity and oxidation resistance of silicon carbide composite materials while maintaining good mechanical properties. Detailed Implementation

[0027] To better understand the present invention, the following embodiments further illustrate the content of the invention, but the scope of protection of the present invention is not limited to the following embodiments. Numerous specific details are set forth in the following description to provide a more thorough understanding of the invention. However, it will be apparent to those skilled in the art that the present invention can be practiced without one or more of these details.

[0028] Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this invention.

[0029] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0030] Unless otherwise specified, all raw materials are derived from commercially available products and do not contain any unspecified components other than unavoidable impurities.

[0031] The zinc oxide aluminum powder is derived from commercially available products, with a purity of ≥99.9% and a particle size of 20~40 nm.

[0032] Anhydrous ethanol was used in all cases.

[0033] A zinc-aluminum oxide-doped silicon carbide conductive composite material is composed of the following raw materials in parts by weight: 52 parts SiC, 25 parts zinc-aluminum oxide powder, 5 parts sintering aid, and 4 parts binder.

[0034] The zinc oxide aluminum powder is zinc oxide doped with 1% alumina by mass. The sintering aid is Y2O3. The binder is a 5% (w / w) aqueous solution of polyvinyl alcohol.

[0035] The preparation method of the above-mentioned zinc oxide aluminum doped silicon carbide conductive composite material includes the following steps:

[0036] S01: Take SiC, zinc-aluminum oxide powder from the first part, and sintering aids, add ethanol solution, stir, ball mill, mix evenly to obtain slurry;

[0037] S02: The slurry is dried in a vacuum drying oven, a binder is added, it is formed by isostatic pressing, and then dried in a vacuum drying oven to obtain a ceramic green body;

[0038] S03: The second part of zinc-aluminum oxide powder is used to prepare a surface coating of ceramic green body to obtain a composite green body;

[0039] S04: The composite green body is sintered in an air atmosphere, heated to 700 ℃ in an oxidation furnace at 6.5 ℃ / min and held for 3 h, then heated to 1000 ℃ at 5 ℃ / min and held for 2 h, and finally heated to 1300 ℃ at 2 ℃ / min and held for 2 h. The sintered green body is cooled with the furnace to obtain the composite ceramic.

[0040] The mass ratio of the first part of zinc oxide aluminum powder to the second part of zinc oxide aluminum powder is 1:0.7; the ball milling adopts a planetary ball mill, with a rotation speed of 300 r / min and unidirectional operation for 2 hours; the isostatic pressing pressure is 150 MPa; the surface coating is prepared by plasma spraying, and the coating thickness is about 30 μm.

[0041] A zinc-aluminum oxide-doped silicon carbide conductive composite material is composed of the following raw materials in parts by weight: 60 parts SiC, 30 parts zinc-aluminum oxide powder, 7 parts sintering aid, and 6 parts binder.

[0042] The zinc oxide aluminum powder is zinc oxide doped with 2% aluminum oxide by mass. The sintering aid is MgO. The binder is an 8% (w / w) aqueous solution of polyvinyl alcohol.

[0043] The preparation method of the above-mentioned zinc oxide aluminum doped silicon carbide conductive composite material includes the following steps:

[0044] S01: Take SiC, zinc-aluminum oxide powder from the first part, and sintering aids, add ethanol solution, stir, ball mill, mix evenly to obtain slurry;

[0045] S02: The slurry is dried in a vacuum drying oven, a binder is added, it is formed by isostatic pressing, and then dried in a vacuum drying oven to obtain a ceramic green body;

[0046] S03: The second part of zinc-aluminum oxide powder is used to prepare a surface coating of ceramic green body to obtain a composite green body;

[0047] S04: The composite green body is sintered in an air atmosphere, heated to 750 ℃ ​​in an oxidation furnace at 5 ℃ / min and held for 3 h, then heated to 1050 ℃ at 5.5 ℃ / min and held for 2.5 h, and finally heated to 1350 ℃ at 2.5 ℃ / min and held for 1.5 h. The sintered green body is cooled with the furnace to obtain the composite ceramic.

[0048] The mass ratio of the first part of zinc-aluminum oxide powder to the second part of zinc-aluminum oxide powder is 1:0.6; the ball milling adopts a planetary ball mill, with a rotation speed of 250 r / min and unidirectional operation for 1.5 h; the isostatic pressing pressure is 100 MPa; the surface coating is prepared by vacuum impregnation followed by high-temperature firing, with a high-temperature firing temperature of 1100 ℃; the coating thickness is approximately 120 μm.

[0049] A zinc-aluminum oxide-doped silicon carbide conductive composite material is composed of the following raw materials in parts by weight: 75 parts SiC, 40 parts zinc-aluminum oxide powder, 8 parts sintering aid, and 8 parts binder.

[0050] The zinc oxide aluminum powder is zinc oxide doped with 3% alumina by mass. The sintering aid is TiO2. The binder is a 3% (w / w) aqueous solution of polyvinyl alcohol.

[0051] The preparation method of the above-mentioned zinc oxide aluminum doped silicon carbide conductive composite material includes the following steps:

[0052] S01: Provide SiC, zinc-aluminum oxide powder (first part), and sintering aids, add ethanol solution, stir, ball mill, mix evenly to obtain slurry;

[0053] S02: The slurry is dried in a vacuum drying oven, a binder is added, it is formed by isostatic pressing, and then dried in a vacuum drying oven to obtain a ceramic green body;

[0054] S03: The second part of zinc-aluminum oxide powder is used to prepare a surface coating of ceramic green body to obtain a composite green body;

[0055] S04: The composite green body is sintered in an air atmosphere, heated to 650 ℃ in an oxidation furnace at 8 ℃ / min and held for 4 h, then heated to 900 ℃ at 6 ℃ / min and held for 3 h, and finally heated to 1200 ℃ at 3 ℃ / min and held for 3 h. The sintered green body is cooled with the furnace to obtain the composite ceramic.

[0056] The mass ratio of the first part of zinc-aluminum oxide powder to the second part of zinc-aluminum oxide powder is 1:0.5; the ball milling adopts a planetary ball mill, with a rotation speed of 400 r / min and unidirectional operation for 1 h; the isostatic pressing pressure is 200 MPa; the surface coating is prepared by brushing followed by high-temperature firing, with a high-temperature firing temperature of 1500 ℃; the coating thickness is approximately 250 μm.

[0057] A zinc-aluminum oxide-doped silicon carbide conductive composite material is composed of the following raw materials in parts by weight: 40 parts SiC, 20 parts zinc-aluminum oxide powder, 2 parts sintering aid, and 2 parts binder.

[0058] The zinc oxide aluminum powder is zinc oxide doped with 4% aluminum oxide by mass. The sintering aid is a combination of Y₂O₃ and MgO in a mass ratio of 1:1. The binder is a 10% (w / w) ethanol solution of phenolic resin.

[0059] The preparation method of the above-mentioned zinc oxide aluminum doped silicon carbide conductive composite material includes the following steps:

[0060] S01: Provide SiC, zinc-aluminum oxide powder (first part), and sintering aids, add ethanol solution, stir, ball mill, mix evenly to obtain slurry;

[0061] S02: The slurry is dried in a vacuum drying oven, a binder is added, it is formed by isostatic pressing, and then dried in a vacuum drying oven to obtain a ceramic green body;

[0062] S03: The second part of zinc-aluminum oxide powder is used to prepare a surface coating of ceramic green body to obtain a composite green body;

[0063] S04: The composite green body is sintered in an air atmosphere, heated to 800℃ in an oxidation furnace at 10℃ / min and held for 2 hours, then heated to 900℃ at 4℃ / min and held for 3 hours, and finally heated to 1400℃ at 1.5℃ / min and held for 1 hour. The sintered green body is cooled with the furnace to obtain the composite ceramic.

[0064] The mass ratio of the first part of zinc oxide aluminum powder to the second part of zinc oxide aluminum powder is 1:0.8; the ball milling adopts a planetary ball mill, with a rotation speed of 350 r / min and unidirectional operation for 1.5 h; the isostatic pressing pressure is 175 MPa; the surface coating is prepared by flame spraying; the coating thickness is about 40 μm.

[0065] A zinc-aluminum oxide-doped silicon carbide conductive composite material is composed of the following raw materials in parts by weight: 80 parts SiC, 60 parts zinc-aluminum oxide powder, 10 parts sintering aid, and 10 parts binder.

[0066] The zinc oxide aluminum powder is zinc oxide doped with 5% aluminum oxide by mass. The sintering aid is a combination of Y2O3, MgO and TiO2 in a mass ratio of 1:1:1. The binder is a 5% (w / w) aqueous solution of polyvinylpyrrolidone.

[0067] The preparation method of the above-mentioned zinc oxide aluminum doped silicon carbide conductive composite material includes the following steps:

[0068] S01: Provide SiC, zinc-aluminum oxide powder (first part), and sintering aids, add ethanol solution, stir, ball mill, mix evenly to obtain slurry;

[0069] S02: The slurry is dried in a vacuum drying oven, a binder is added, it is formed by isostatic pressing, and then dried in a vacuum drying oven to obtain a ceramic green body;

[0070] S03: The second part of zinc-aluminum oxide powder is used to prepare a surface coating of ceramic green body to obtain a composite green body;

[0071] S04: The composite green body is sintered in an air atmosphere, heated to 600 ℃ in an oxidation furnace at 5 ℃ / min and held for 4 h, then heated to 950 ℃ at 4.5 ℃ / min and held for 2.5 h, and finally heated to 1250 ℃ at 1 ℃ / min and held for 1.5 h. The sintered green body is cooled with the furnace to obtain the composite ceramic.

[0072] The mass ratio of the first part of zinc-aluminum oxide powder to the second part of zinc-aluminum oxide powder is 1:1; the ball milling adopts a planetary ball mill, with a rotation speed of 300 r / min and unidirectional operation for 2 hours; the isostatic pressing pressure is 160 MPa; the surface coating is prepared by vacuum impregnation followed by high-temperature firing, with a high-temperature firing temperature of 1400 ℃; the coating thickness is approximately 260 μm.

[0073] Comparative Example 1

[0074] A method for preparing a silicon carbide composite material includes the following steps:

[0075] SiC, zinc oxide aluminum powder, and sintering aids were added to an ethanol solution, stirred, ball-milled, and mixed evenly to obtain a slurry. The slurry was dried in a vacuum drying oven, a binder was added, and the mixture was isostatically pressed and dried in a vacuum drying oven to obtain a ceramic green body. The ceramic green body was sintered under an argon atmosphere, heated to 700 ℃ at 6.5 ℃ / min in a nitriding furnace, held for 3 h, then heated to 1000 ℃ at 5 ℃ / min, held for 2 h, and finally heated to 1300 ℃ at 2 ℃ / min, held for 2 h. The sintered green body was cooled with the furnace to obtain a composite ceramic.

[0076] The relevant process parameters in this comparative preparation method are the same as in Example 1; the composition of each raw material and its weight parts are the same as in Example 1.

[0077] Comparative Example 2

[0078] The preparation method of the above-mentioned silicon carbide composite material includes the following steps:

[0079] SiC and sintering aids were added to an ethanol solution, stirred, ball-milled, and mixed evenly to obtain a slurry. The slurry was dried in a vacuum drying oven, a binder was added, and the mixture was isostatically pressed and dried in a vacuum drying oven to obtain a ceramic green body. The zinc-alumina powder from the second part was used to prepare a surface coating for the ceramic green body to obtain a composite green body. The composite green body was sintered in an air atmosphere by heating to 700 ℃ at 6.5 ℃ / min in an oxidation furnace and holding for 3 h, then heating to 1000 ℃ at 5 ℃ / min and holding for 2 h, and finally heating to 1300 ℃ at 2 ℃ / min and holding for 2 h. The sintered green body was cooled with the furnace to obtain the composite ceramic.

[0080] The relevant process parameters in this comparative preparation method are the same as in Example 1; the composition of each raw material and its weight parts are the same as in Example 1.

[0081] Comparative Example 3

[0082] A silicon carbide material comprises the following raw materials in parts by weight: 52 parts SiC, 5 parts sintering aid, and 4 parts binder. The sintering aid is Y₂O₃. The binder is a 5% (w / w) aqueous solution of polyvinyl alcohol.

[0083] Its preparation method includes the following steps:

[0084] SiC and sintering aids were added to an ethanol solution, stirred, ball-milled, and mixed evenly to obtain a slurry. The slurry was dried in a vacuum drying oven, a binder was added, and the mixture was isostatically pressed and dried in a vacuum drying oven to obtain a ceramic green body. The ceramic green body was sintered in a vacuum environment by heating to 700 ℃ at 6.5 ℃ / min in a vacuum furnace and holding for 3 h, then heating to 1000 ℃ at 5 ℃ / min and holding for 2 h, and finally heating to 1300 ℃ at 2 ℃ / min and holding for 2 h. The sintered green body was cooled with the furnace to obtain the ceramic material.

[0085] The relevant process parameters in this comparative preparation method are the same as those in Example 1.

[0086] Comparative Example 4

[0087] A silicon carbide composite material is composed of the following raw materials in parts by weight: 52 parts SiC, 22 parts zinc oxide, 3 parts aluminum oxide, 5 parts sintering aid, and 4 parts binder.

[0088] The sintering aid is Y2O3. The binder is a 5% (w / w) aqueous solution of polyvinyl alcohol.

[0089] The preparation method of the above-mentioned silicon carbide composite material includes the following steps:

[0090] SiC, zinc oxide, aluminum oxide, and sintering aids were added to an ethanol solution, stirred, ball-milled, and mixed evenly to obtain a slurry. The slurry was dried in a vacuum drying oven, a binder was added, and the mixture was isostatically pressed and dried in a vacuum drying oven to obtain a ceramic green body. The ceramic green body was sintered under an argon atmosphere, heated to 700 ℃ at 6.5 ℃ / min in a nitriding furnace, held for 3 h, then heated to 1000 ℃ at 5 ℃ / min, held for 2 h, and finally heated to 1300 ℃ at 2 ℃ / min, held for 2 h. The sintered green body was cooled with the furnace to obtain a composite ceramic.

[0091] The relevant process parameters in this comparative preparation method are the same as those in Example 1.

[0092] Example of effect test:

[0093] The materials prepared in Examples 1-5 and Comparative Examples 1-4 were subjected to the following performance tests:

[0094] (1) Determination of apparent porosity and bulk density: Archimedes' water displacement method.

[0095] (2) Resistivity: DC four-probe method, test temperature 25 ℃, test current 100 mA.

[0096] (3) Pressure resistance: pressure testing machine.

[0097] (4) Vickers hardness: Vickers hardness tester.

[0098] (5) Fracture toughness: Fracture toughness testing machine.

[0099] (6) Antioxidant properties: Simultaneous thermal analyzer.

[0100] The test results are shown in Tables 1 and 2.

[0101] Table 1 Performance test results of Examples 1-5

[0102]

[0103] As shown in Table 1, the resistivity of the composite material of this invention is <4.0×10⁻⁶. -2 Ω·cm, oxidation weight gain <4.0%, and bulk density 3.5~3.7 g / cm³. 3 It has an apparent porosity of 8.5–11.0%, a compressive strength of 230–250 MPa, a Vickers hardness of 7.0–8.0 GPa, and a fracture toughness of 10.0–11.0 MPa·m. 1 / 2 .

[0104] Table 2 Performance test results of Comparative Examples 1-4

[0105]

[0106] As shown in Table 2, the difference between Comparative Example 1 and Example 1 lies in omitting the preparation of the zinc oxide aluminum powder coating. The resistivity and oxidation weight gain of the resulting composite ceramic are significantly increased, while the bulk density, apparent porosity, compressive strength, Vickers hardness, and fracture toughness show no significant changes. Therefore, the preparation of the zinc oxide aluminum powder coating in this invention not only affects the product's oxidation resistance but also significantly improves its overall conductivity.

[0107] The difference between Comparative Example 2 and Example 1 is that zinc oxide aluminum powder was only used to prepare the coating of the ceramic body. The resistivity of the resulting composite ceramic increased significantly, while the oxidation weight gain rate was not significantly different from that of Example 1. Furthermore, other performance indicators tested were also not significantly different. It is evident that simply preparing a zinc oxide aluminum powder coating does not significantly improve the conductivity of the product. Moreover, more zinc oxide aluminum powder is not necessarily better; increasing the amount used does not significantly improve its antioxidant properties.

[0108] The difference between Comparative Example 3 and Example 1 is that the use of zinc aluminum oxide powder is omitted. The resulting silicon carbide ceramic has a higher apparent porosity, a lower compressive strength, poor electrical conductivity, and a significant increase in oxidation weight gain. It can be seen that the raw material combination and the overall effect of the silicon carbide ceramic material prepared in this invention are more significant.

[0109] The difference between Comparative Example 4 and Example 1 is that aluminum oxide and zinc oxide are used instead of zinc aluminum oxide powder. The electrical conductivity and oxidation resistance of the resulting ceramic material are far inferior to those of Example 1. It can be seen that the overall effect of using zinc aluminum oxide powder in this invention is superior.

[0110] In summary, this invention, through rational optimization of the raw material composition of silicon carbide ceramic materials and the combination of scientific preparation methods, enables silicon carbide composite materials to significantly improve their electrical conductivity and oxidation resistance while maintaining good mechanical properties.

[0111] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solutions of the present invention, as long as they do not depart from the spirit and scope of the technical solutions of the present invention, should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing a zinc oxide-aluminum doped silicon carbide conductive composite material, characterized in that: Includes the following steps: S01: Provide SiC, zinc-aluminum oxide powder (first part), and sintering aids, add ethanol solution, stir, ball mill, mix evenly to obtain slurry; S02: The slurry is dried in a vacuum drying oven, a binder is added, it is formed by isostatic pressing, and then dried in a vacuum drying oven to obtain a ceramic green body; S03: The second part of zinc-aluminum oxide powder is used to prepare a surface coating of ceramic green body to obtain a composite green body; The surface coating is prepared by one of the following methods: high-temperature firing after brushing, high-temperature firing after vacuum impregnation, plasma spraying, and flame spraying. S04: The composite green body is sintered in an air atmosphere, heated to 600-800 ℃ in an oxidation furnace at 5-10 ℃ / min and held for 2-4 h, then heated to 900-1100 ℃ at 4-6 ℃ / min and held for 1-3 h, and finally heated to 1200-1400 ℃ at 1-3 ℃ / min and held for 1-3 h. The sintered green body is cooled with the furnace to obtain the composite ceramic. The SiC comprises 40-80 parts by weight, the zinc-aluminum oxide powder comprises 20-60 parts by weight, the sintering aid comprises 2-10 parts by weight, and the binder comprises 2-10 parts by weight. The zinc-aluminum oxide powder is zinc oxide doped with 1-5% alumina by weight. The mass ratio of the first part of the zinc-aluminum oxide powder to the second part of the zinc-aluminum oxide powder is 1:(0.5-1). The sintering aid is one or a combination of two or more of Y2O3, MgO, and TiO2.

2. The method for preparing a zinc oxide aluminum doped silicon carbide conductive composite material as described in claim 1, characterized in that: The ball mill is a planetary ball mill, running unidirectionally for 1 to 3 hours at a speed of 200 to 400 r / min.

3. The method for preparing a zinc oxide aluminum doped silicon carbide conductive composite material as described in claim 2, characterized in that: The isostatic pressing pressure is 100~200 MPa.

4. The method for preparing a zinc oxide aluminum doped silicon carbide conductive composite material as described in claim 3, characterized in that: The thickness of the coating is 10~300 μm.

5. The method for preparing a zinc oxide aluminum doped silicon carbide conductive composite material as described in claim 4, characterized in that: The adhesive is an alcohol solution or aqueous solution of one or more of polyvinyl alcohol, phenolic resin and polyvinylpyrrolidone.

Images