Beta-alumina conductive ceramic material and preparation method thereof

Abstract

The invention discloses a beta-alumina conductive ceramic material and a preparation method thereof, and belongs to the technical field of conductive ceramic materials.The material is prepared from, by mass, 99.5-100 parts of beta-alumina powder and 0.0-0.5 part of yttrium oxide; the beta-alumina powder is prepared from the following raw materials in parts by mass: 91.366 parts of alumina nano powder and 8.634 parts of sodium carbonate. The high-activity alumina powder and doped yttrium oxide are used, in the high-temperature sintering process, sintering resistance is greatly reduced, grain development is promoted, compact sintering is promoted, yttrium oxide is added into a reaction system in a matched mode, yttrium ions replace part of aluminum ions to form a limited solid solution, lattice distortion is generated, compact sintering is further promoted, and high-temperature sintering is achieved. The sintering temperature can be greatly reduced (the sintering temperature is reduced by 200 DEG C), the energy consumption is reduced, so that the preparation cost is reduced, and compared with foreign electronic ceramics, the competitiveness is improved, and popularization is facilitated.

Description

Technical Field

[0001] The present application relates to the technical field of conductive ceramic materials, and in particular to a β-alumina conductive ceramic material and a preparation method thereof. Background Art

[0002] Ceramic materials refer to a class of inorganic non-metallic materials made from natural or synthetic compounds through forming and high-temperature sintering. They have the advantages of high melting point, high hardness, high wear resistance, and oxidation resistance. They can be used as structural materials and tool materials. Since ceramics also have certain special properties, they can be used as functional materials and can be applied to new energy vehicles to solve the problem of automobile pollution in urban air.

[0003] At present, with the rapid development of urban automobile technology in my country, the requirements for ceramic materials used in urban environmental protection have also increased. Ceramic materials are required to have high conductivity, small size, high density, high volume density and mechanical strength, as well as oxidation resistance and good thermal stability.

[0004] While metals also have high electrical conductivity, they are more expensive and more susceptible to oxidation than ceramics. Ceramic materials are both inexpensive and resistant to oxidation, and their electrical conductivity rivals that of metals. While ordinary alumina powder can also achieve good electrical conductivity, its sintering temperature is very high, at 1650-1710°C, resulting in high energy consumption. This reduces its competitiveness compared to foreign electronic ceramics, hindering their widespread adoption.

[0005] Therefore, how to develop a β-alumina conductive ceramic material with low energy consumption, low cost and better conductive performance and a preparation method thereof is a technical problem that is urgently needed to be solved by those skilled in the art. Summary of the Invention

[0006] In view of this, the present invention provides a β-alumina conductive ceramic material and a preparation method thereof.

[0007] A β-alumina conductive ceramic material is prepared by including the following raw materials in parts by weight:

[0008] 99.5-100 parts of β-alumina powder, 0.0-0.5 parts of yttrium oxide;

[0009] The β-alumina powder is prepared by including the following raw materials in parts by mass: 91.366 parts of alumina nanopowder and 8.634 parts of sodium carbonate.

[0010] Furthermore, the alumina nanopowder is γ-alumina, and its specific surface area is 13112m 2 / kg.

[0011] The present invention also provides a method for preparing a β-alumina conductive ceramic material, comprising the following steps:

[0012] (1) Weighing various raw materials according to the β-alumina conductive ceramic material;

[0013] (2) adding alumina nanopowder, sodium carbonate, a ball milling medium, and deionized water into a ball mill for ball milling, drying the obtained slurry and then calcining it at a constant temperature to obtain β-alumina powder;

[0014] (3) adding the β-alumina powder and yttrium oxide obtained in step (2) to a ball mill with a ball milling medium and deionized water for secondary ball milling, and placing the obtained slurry in a granulation tower for spray granulation to obtain spherical particles;

[0015] (4) placing the spherical particles obtained in step (3) in a dry press and pressing them to obtain a green body;

[0016] (5) bisque-firing the green body obtained in step (4) at a constant temperature, then soaking it in a saturated solution of NaOH with a concentration of 52 wt%, and baking it to obtain a porcelain body;

[0017] (6) The ceramic blank obtained in step (5) is heated, sealed and sintered at a constant temperature, and cut into thin slices to obtain the β-alumina conductive ceramic material.

[0018] Furthermore, in step (2), the mass ratio of the total mass of alumina nanopowder and sodium carbonate, the ball milling medium and deionized water is 1:4:2; the ball milling time is 8 hours, and the obtained slurry particle size is 2-3 μm; the drying temperature is 300°C, and the drying time is 3-4 hours; the constant temperature calcination temperature is 1050°C, and the constant temperature calcination time is 3 hours.

[0019] Furthermore, in step (3), the mass ratio of the total mass of β-alumina powder and yttrium oxide, the ball milling medium and deionized water is 1:4:2, the ball milling time is 8 hours, and the obtained slurry particle size is 2-3 μm; the spray granulation inlet air temperature is 320°C, the outlet air temperature is 120°C, the nozzle speed is 22 Hz, and the feed speed is 120-130 Hz.

[0020] Further, in step (2) and step (3), the ball milling medium is Zirconia balls.

[0021] Furthermore, in step (3), the particle size of the spherical particles is 100 mesh.

[0022] Furthermore, in step (4), the pressing pressure is 500-750 MPa.

[0023] Furthermore, in step (5), the green body is calcined at a constant temperature of 1200°C for 3 hours; the green body is immersed in a saturated solution of NaOH with a concentration of 52wt% for 10 minutes; and the drying temperature is 300°C for 0.5 hours.

[0024] Furthermore, in step (6), the temperature is raised to 1450-1510° C. and then sealed and sintered at a constant temperature for 5 hours.

[0025] The beneficial effects of the present invention are as follows: the present invention uses high-activity alumina powder and doped yttrium oxide to greatly reduce the sintering resistance during high-temperature sintering, promote grain development and thus promote dense sintering; and then, by adding yttrium oxide to the reaction system, yttrium ions replace part of the aluminum ions to form a limited solid solution, resulting in lattice distortion, thereby further promoting dense sintering, which can greatly reduce the sintering temperature (reducing the sintering temperature by 200°C), reduce energy consumption, and thus reduce the preparation cost. Compared with foreign electronic ceramics, the present invention has improved competitiveness and is conducive to promotion. In addition, without the addition of yttrium oxide, Na ions can only move relatively freely between the Al-O-Al bond spinel blocks. After doping with yttrium oxide, due to the large difference in ionic radius between Y ions (ionic radius 0.088nm) and Al ions (0.053nm), it is more likely to produce lattice distortion and thus easier to sinter. Y ions replace part of the Al ions to form a limited solid solution, allowing Na ions to move freely between the Al-O-Al bond and the Al-OY bond spinel blocks faster, thereby improving the conductivity.

[0026] The volume density of the β-alumina ceramic material of the present invention is greater than 3.2 g / cm 3 , conductivity>0.05 / Ωcm, thermal stability from 25-800℃ rapid cooling and heating cycles 10 times without cracking. DETAILED DESCRIPTION

[0027] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0028] The purity of the aluminum oxide, yttrium oxide and sodium carbonate used in the examples of the present invention and the comparative examples is 99.9%.

[0029] Example 1

[0030] The preparation method of β-alumina powder comprises the following steps:

[0031] (1) Weigh the specific surface area to be 13112m 2 / kg of γ-alumina nanopowder 1827.32 g, sodium carbonate 172.68 g;

[0032] (2) Alumina nanopowder and sodium carbonate are mixed with ball milling media Zirconia balls and deionized water are added into a ball mill in a mass ratio of 1:4:2 to the total mass of alumina nanopowder and sodium carbonate, ball milling medium and deionized water, and ball milling is carried out for 8 hours. The obtained slurry with a particle size of 2-3 μm is dried at a drying temperature of 300°C for 3 hours and then calcined at a constant temperature of 1050°C for 3 hours to obtain β-alumina powder, i.e., Na2O·11Al2O3 powder.

[0033] Example 2

[0034] The preparation method of β-alumina conductive ceramic material comprises the following steps:

[0035] (1) Weigh 199.8 g of β-alumina powder and 0.2 g of yttrium oxide from Example 1, and mix the β-alumina powder and yttrium oxide with the ball milling medium. Zirconia balls and deionized water were added into a ball mill in a mass ratio of 1:4:2 according to the total mass of β-alumina powder and yttrium oxide, ball milling medium and deionized water, and secondary ball milling was carried out for 8 hours. The obtained slurry with a particle size of 2-3 μm was pumped into a granulation tower through a peristaltic pump for spray granulation. The inlet air temperature was 320°C, the outlet air temperature was 120°C, the nozzle speed was 22Hz, and the feed speed was 125Hz to obtain spherical particles with a particle size of 100 mesh (0.149mm) with uniform fluidity.

[0036] (2) placing the spherical particles obtained in step (1) in a 100T dry press and pressing at 550 MPa to obtain a green body;

[0037] (3) bisque-firing the green body obtained in step (2) at a constant temperature of 1200° C. for 3 h, then soaking it in a saturated solution of 52 wt% NaOH for 10 minutes, and drying it at 300° C. for 0.5 h to obtain a porcelain body;

[0038] (4) The ceramic blank obtained in step (3) is placed in a corundum crucible, and the corundum crucible is heated to 1500° C. in a silicon-molybdenum rod furnace and then sealed and sintered at a constant temperature for 5 h. The ceramic blank is then cut into 10*10*1.0 mm thin slices by wire cutting to obtain a β-alumina conductive ceramic material.

[0039] Example 3

[0040] The preparation method of β-alumina conductive ceramic material comprises the following steps:

[0041] (1) Weigh 199.6 g of β-alumina powder and 0.4 g of yttrium oxide from Example 1, and mix the β-alumina powder and yttrium oxide with the ball milling medium. Zirconia balls and deionized water were added into a ball mill in a mass ratio of 1:4:2 according to the total mass of β-alumina powder and yttrium oxide, ball milling medium and deionized water, and secondary ball milling was carried out for 8 hours. The obtained slurry with a particle size of 2-3 μm was pumped into a granulation tower through a peristaltic pump for spray granulation. The inlet air temperature was 320°C, the outlet air temperature was 120°C, the nozzle speed was 22Hz, and the feed speed was 125Hz to obtain spherical particles with a particle size of 100 mesh (0.149mm) with uniform fluidity.

[0042] (2) placing the spherical particles obtained in step (1) in a 100T dry press and pressing at 550 MPa to obtain a green body;

[0043] (3) bisque-firing the green body obtained in step (2) at a constant temperature of 1200° C. for 3 h, then soaking it in a saturated solution of 52 wt% NaOH for 10 minutes, and drying it at 300° C. for 0.5 h to obtain a porcelain body;

[0044] (4) The ceramic blank obtained in step (3) is placed in a corundum crucible, and the corundum crucible is heated to 1500° C. in a silicon-molybdenum rod furnace and then sealed and sintered at a constant temperature for 5 h. The ceramic blank is then cut into 10*10*1.0 mm thin slices by wire cutting to obtain a β-alumina conductive ceramic material.

[0045] Example 4

[0046] The preparation method of β-alumina conductive ceramic material comprises the following steps:

[0047] (1) Weigh 199.4 g of β-alumina powder and 0.6 g of yttrium oxide from Example 1, and mix the β-alumina powder and yttrium oxide with the ball milling medium. Zirconia balls and deionized water were added into a ball mill in a mass ratio of 1:4:2 according to the total mass of β-alumina powder and yttrium oxide, ball milling medium and deionized water, and secondary ball milling was carried out for 8 hours. The obtained slurry with a particle size of 2-3 μm was pumped into a granulation tower through a peristaltic pump for spray granulation. The inlet air temperature was 320°C, the outlet air temperature was 120°C, the nozzle speed was 22Hz, and the feed speed was 125Hz to obtain spherical particles with a particle size of 100 mesh (0.149mm) with uniform fluidity.

[0048] (2) placing the spherical particles obtained in step (1) in a 100T dry press and pressing at 550 MPa to obtain a green body;

[0049] (3) bisque-firing the green body obtained in step (2) at a constant temperature of 1200° C. for 3 h, then soaking it in a saturated solution of 52 wt% NaOH for 10 minutes, and drying it at 300° C. for 0.5 h to obtain a porcelain body;

[0050] (4) The ceramic blank obtained in step (3) is placed in a corundum crucible, and the corundum crucible is heated to 1500° C. in a silicon-molybdenum rod furnace and then sealed and sintered at a constant temperature for 5 h. The ceramic blank is then cut into 10*10*1.0 mm thin slices by wire cutting to obtain a β-alumina conductive ceramic material.

[0051] Example 5

[0052] The preparation method of β-alumina conductive ceramic material comprises the following steps:

[0053] (1) Weigh 199.2 g of β-alumina powder and 0.8 g of yttrium oxide from Example 1, and mix the β-alumina powder and yttrium oxide with the ball milling medium. Zirconia balls and deionized water were added into a ball mill in a mass ratio of 1:4:2 according to the total mass of β-alumina powder and yttrium oxide, ball milling medium and deionized water, and secondary ball milling was carried out for 8 hours. The obtained slurry with a particle size of 2-3 μm was pumped into a granulation tower through a peristaltic pump for spray granulation. The inlet air temperature was 320°C, the outlet air temperature was 120°C, the nozzle speed was 22Hz, and the feed speed was 125Hz to obtain spherical particles with a particle size of 100 mesh (0.149mm) with uniform fluidity.

[0054] (2) placing the spherical particles obtained in step (1) in a 100T dry press and pressing at 550 MPa to obtain a green body;

[0055] (3) bisque-firing the green body obtained in step (2) at a constant temperature of 1200° C. for 3 h, then soaking it in a saturated solution of 52 wt% NaOH for 10 minutes, and drying it at 300° C. for 0.5 h to obtain a porcelain body;

[0056] (4) The ceramic blank obtained in step (3) is placed in a corundum crucible, and the corundum crucible is heated to 1500° C. in a silicon-molybdenum rod furnace and then sealed and sintered at a constant temperature for 5 h. The ceramic blank is then cut into 10*10*1.0 mm thin slices by wire cutting to obtain a β-alumina conductive ceramic material.

[0057] Example 6

[0058] The preparation method of β-alumina conductive ceramic material comprises the following steps:

[0059] (1) Weigh 199.0 g of β-alumina powder and 1.0 g of yttrium oxide from Example 1, and mix the β-alumina powder and yttrium oxide with the ball milling medium. Zirconia balls and deionized water were added into a ball mill in a mass ratio of 1:4:2 according to the total mass of β-alumina powder and yttrium oxide, ball milling medium and deionized water, and secondary ball milling was carried out for 8 hours. The obtained slurry with a particle size of 2-3 μm was pumped into a granulation tower through a peristaltic pump for spray granulation. The inlet air temperature was 320°C, the outlet air temperature was 120°C, the nozzle speed was 22Hz, and the feed speed was 125Hz to obtain spherical particles with a particle size of 100 mesh (0.149mm) with uniform fluidity.

[0060] (2) placing the spherical particles obtained in step (1) in a 100T dry press and pressing at 550 MPa to obtain a green body;

[0061] (3) bisque-firing the green body obtained in step (2) at a constant temperature of 1200° C. for 3 h, then soaking it in a saturated solution of 52 wt% NaOH for 10 minutes, and drying it at 300° C. for 0.5 h to obtain a porcelain body;

[0062] (4) The ceramic blank obtained in step (3) is placed in a corundum crucible, and the corundum crucible is heated to 1500° C. in a silicon-molybdenum rod furnace and then sealed and sintered at a constant temperature for 5 h. The ceramic blank is then cut into 10*10*1.0 mm thin slices by wire cutting to obtain a β-alumina conductive ceramic material.

[0063] Comparative Example 1

[0064] The preparation method of β-alumina conductive ceramic material comprises the following steps:

[0065] (1) Weigh 200 g of β-alumina powder from Example 1 and mix it with the ball milling medium. Zirconia balls and deionized water were added into a ball mill in a mass ratio of 1:4:2 according to the total mass of β-alumina powder and yttrium oxide, ball milling medium and deionized water, and secondary ball milling was carried out for 8 hours. The obtained slurry with a particle size of 2-3 μm was pumped into a granulation tower through a peristaltic pump for spray granulation. The inlet air temperature was 320°C, the outlet air temperature was 120°C, the nozzle speed was 22Hz, and the feed speed was 125Hz to obtain spherical particles with a particle size of 100 mesh (0.149mm) with uniform fluidity.

[0066] (2) placing the spherical particles obtained in step (1) in a 100T dry press and pressing at 550 MPa to obtain a green body;

[0067] (3) bisque-firing the green body obtained in step (2) at a constant temperature of 1200° C. for 3 h, then soaking it in a saturated solution of 52 wt% NaOH for 10 minutes, and drying it at 300° C. for 0.5 h to obtain a porcelain body;

[0068] (4) The ceramic blank obtained in step (3) is placed in a corundum crucible, and the corundum crucible is heated to 1500° C. in a silicon-molybdenum rod furnace and then sealed and sintered at a constant temperature for 5 h. The ceramic blank is then cut into 10*10*1.0 mm thin slices by wire cutting to obtain a β-alumina conductive ceramic material.

[0069] The performance of the ceramic materials prepared in the above-mentioned embodiments and comparative examples was tested, and the test results are shown in Table 1.

[0070] Table 1 Performance test results of ceramic materials obtained in Examples 2-6 and Comparative Example 1

[0071]

[0072]

[0073] As can be clearly seen from Table 1 above, the sintering temperature can be reduced to below 1510°C by the formulation and preparation method of the present invention. Compared with the conventional sintering process which requires 1650-1710°C, the sintering temperature is significantly reduced by about 200°C. The bulk density of the obtained conductive ceramic material is greater than 3.2g / cm 3 , with a conductivity of >0.05 / ohm.cm, and excellent thermal stability, capable of 10 continuous cycles from room temperature (25-800°C) without cracking. Furthermore, the conductivity of the doped yttrium oxide is significantly improved compared to the undoped version. Furthermore, the formulation of the present invention does not contain heavy metals such as lead, chromium, and mercury, making it an environmentally friendly ceramic that meets green and pollution-free requirements. Furthermore, it complies with the EU's latest lead-free standards and the stringent ROHS and WEEE standards for recycling waste electrical appliances, making it suitable for use in automotive, electronics, and battery products, and can be exported to any country in the world.

[0074] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A β-alumina conductive ceramic material, characterized in that: The method is prepared by comprising the following raw materials in parts by weight: 99.5-100 parts of β-alumina powder, 0.0-0.5 parts of yttrium oxide; The β-alumina powder is prepared by including the following raw materials in parts by mass: 91.366 parts of alumina nanopowder and 8.634 parts of sodium carbonate.

2. The β-alumina conductive ceramic material according to claim 1, characterized in that: The alumina nanopowder is γ-alumina, and its specific surface area is 13112m 2 / kg.

3. A method for preparing a β-alumina conductive ceramic material, characterized in that: The following steps are involved: (1) Weighing the raw materials of the β-alumina conductive ceramic material according to any one of claims 1 to 2; (2) adding alumina nanopowder, sodium carbonate, a ball milling medium, and deionized water into a ball mill for ball milling, drying the obtained slurry and then calcining it at a constant temperature to obtain β-alumina powder; (3) adding the β-alumina powder and yttrium oxide obtained in step (2) to a ball mill with a ball milling medium and deionized water for secondary ball milling, and placing the obtained slurry in a granulation tower for spray granulation to obtain spherical particles; (4) placing the spherical particles obtained in step (3) in a dry press and pressing them to obtain a green body; (5) bisque-firing the green body obtained in step (4) at a constant temperature, then soaking it in a saturated solution of NaOH with a concentration of 52 wt%, and baking it to obtain a porcelain body; (6) The ceramic blank obtained in step (5) is heated, sealed and sintered at a constant temperature, and cut into thin slices to obtain the β-alumina conductive ceramic material.

4. The method for preparing a functional composite material based on an inorganic compound system according to claim 1, characterized in that: In step (2), the mass ratio of the total mass of alumina nanopowder and sodium carbonate, ball milling medium and deionized water is 1:4:2; the ball milling time is 8 hours, and the obtained slurry particle size is 2-3 μm; the drying temperature is 300°C, and the drying time is 3-4 hours; the constant temperature calcination temperature is 1050°C, and the constant temperature calcination time is 3 hours.

5. The method for preparing a functional composite material based on an inorganic compound system according to claim 1, characterized in that: In step (3), the mass ratio of the total mass of β-alumina powder and yttrium oxide, ball milling medium and deionized water is 1:4:2, the ball milling time is 8 hours, and the obtained slurry particle size is 2-3 μm; the spray granulation inlet air temperature is 320°C, the outlet air temperature is 120°C, the nozzle speed is 22 Hz, and the feed speed is 120-130 Hz.

6. The method for preparing a functional composite material based on an inorganic compound system according to claim 1, characterized in that: In step (2) and step (3), the ball milling medium is zirconia balls of φ5-φ15.

7. The method for preparing a functional composite material based on an inorganic compound system according to claim 1, characterized in that: In step (3), the particle size of the spherical particles is 100 mesh.

8. The method for preparing a functional composite material based on an inorganic compound system according to claim 1, characterized in that: In step (4), the pressing pressure is 500-750 MPa.

9. The method for preparing a functional composite material based on an inorganic compound system according to claim 1, characterized in that: In step (5), the green body is biscuit fired at a constant temperature of 1200°C for 3 hours; it is immersed in a saturated solution of NaOH with a concentration of 52wt% for 10 minutes; and the drying temperature is 300°C for 0.5 hours.

10. The method for preparing a functional composite material based on an inorganic compound system according to claim 1, characterized in that: In step (6), the temperature is raised to 1450-1510°C and then sealed and sintered at a constant temperature for 5 hours.

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