Alumina-based material with multi-scale particles and preparation method thereof

Abstract

This invention relates to the field of alumina materials technology, specifically providing an alumina-based material with multi-scale particles and its preparation method. The method includes: mixing Al2O3, Ni3Ti, and a CuO / SiC composite material, pressing them into shape, and then vacuum hot-pressing and sintering to obtain an alumina-based material with multi-scale particles. Compared with existing technologies, this invention adds Ni3Ti and CuO / SiC composite material to the alumina matrix, which lowers the sintering temperature while improving the density of the alumina-based material, thereby improving its mechanical properties. Experimental results show that the fracture toughness of the alumina-based material with multi-scale particles prepared by the method provided by this invention is ≥6.7 MPa·m. 1 / 2 Flexural strength ≥746.1MPa, microhardness ≥1821HV.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum oxide materials, and more particularly to an aluminum oxide-based material with multi-scale particles and a preparation method thereof. Background Art

[0002] Ceramic particles have been widely used as a reinforcing phase in metal-based and resin-based composite materials in material design due to their high hardness, high modulus and dimensional stability. In recent years, single ceramic powder or single metal powder has been industrialized, and its particle size has also developed from micron to nanometer. Particle-reinforced alumina-based composite materials have the advantages of both alumina and reinforced particles, with high specific strength and modulus, good thermal and electrical conductivity, and excellent wear resistance. They have broad application prospects in aerospace, automobiles, and advanced weapon systems.

[0003] Alumina has extremely strong ionic bonding properties and its melting point reaches 2050°C, requiring a relatively high sintering temperature. This means that the production process of alumina ceramics requires a large amount of energy and high-calorific value fuels, as well as a large amount of high-temperature fired advanced refractory materials (kiln tools, furnace materials, etc.) and high-temperature heating elements, which limits the development and application of alumina ceramics. In addition, excessively high sintering temperatures cause the main crystal phase grains of the ceramic to grow larger, and residual pores to aggregate and grow, resulting in reduced mechanical properties of the material.

[0004] Therefore, how to reduce the sintering temperature of alumina ceramics and maintain or even improve the mechanical properties of alumina materials is a technical problem that needs to be solved urgently. At present, the sintering temperature of alumina ceramics is mainly reduced by adding sintering aids (TiO2, Cr2O3, MnO2, etc.). However, the mechanical properties of alumina materials prepared by adding aids are relatively low, which still limits the development and application of alumina. Summary of the invention

[0005] In view of this, the object of the present invention is to provide an alumina-based material with multi-scale particles and a preparation method thereof. The method of the present invention can improve the density of the alumina-based material while reducing the sintering temperature, thereby improving the mechanical properties of the alumina-based material.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for preparing an alumina-based material having multi-scale particles, comprising:

[0008] Al2O3, Ni3Ti and CuO / SiC composite materials are mixed, pressed and subsequently sintered by vacuum hot pressing to obtain an alumina-based material with multi-scale particles;

[0009] The vacuum hot pressing sintering specifically includes:

[0010] Under the condition of vacuum degree ≤10kPa, the temperature is raised to 300-400°C at a rate of 40-45°C / min, and then raised to 1700-1800°C at a rate of 20-25°C / min;

[0011] The preparation method of the CuO / SiC composite material comprises:

[0012] SiC whiskers are mixed with CuSO4 solution and NaOH, and heated at a temperature of 150-180° C. to obtain a CuO / SiC composite material.

[0013] Preferably, the vacuum hot pressing sintering specifically includes:

[0014] After the temperature is raised to 300-400° C., the temperature is kept for 25-35 minutes, and then the temperature is raised to 1700-1800° C. at a rate of 20-25° C. / min, and the temperature is kept for 30-40 minutes.

[0015] Preferably, the mass ratio of the Al2O3, Ni3Ti and CuO / SiC composite material is 70:(10-20):(10-20), preferably 70:10:20, 70:20:10 or 70:15:15.

[0016] Preferably, the compression molding pressure is 4-5 MPa, preferably 4 MPa.

[0017] Preferably, the molar ratio of the SiC whisker to the copper ions in the CuSO4 solution is 1:(1.5-2.5).

[0018] Preferably, the molar ratio of the NaOH to the copper ions in the CuSO4 solution is (2-3):1.

[0019] Preferably, the length of the SiC whisker is 40-50 μm, and the aspect ratio is 10:1; the length of the SiC whisker is preferably 50 μm.

[0020] Preferably, the preparation method of the CuO / SiC composite material comprises:

[0021] Take 20g of SiC whiskers with a length of 50μm and an aspect ratio of 10:1, add them to 500mL of CuSO4 solution (0.6mol / L), stir at 200r / min to fully mix the SiC whiskers and CuSO4 solution, then add 40g of NaOH to the system, stir at 200r / min, filter out the precipitate, and heat the precipitate at 150℃ for 10h to obtain SiC whiskers with CuO coated on the surface.

[0022] Preferably, the preparation method of Ni3Ti comprises:

[0023] Ni and Ti are mixed and placed in a vacuum of 10 -2 Pa, heated to 800-850°C and kept warm for 1-3h to obtain Ni3Ti.

[0024] Preferably, the mass ratio of Ni to Ti is (3-5):1, preferably 4:1.

[0025] Preferably, the particle size of Ni is 75 μm; the particle size of Ti is 75 μm.

[0026] Preferably, the preparation method of Ni3Ti comprises:

[0027] Ni metal powder (75 μm) and Ti metal powder (75 μm) with a mass ratio of 4:1 were ball-milled at a speed of 550 r / min and argon for 35 h. -2 Pa and heated to 800 ° C and kept warm for 2 h to obtain Ni3Ti.

[0028] The present invention also provides an alumina-based material with multi-scale particles obtained by the method for preparing the alumina-based material with multi-scale particles.

[0029] Compared with the prior art, the present invention mixes Al2O3, Ni3Ti and CuO / SiC composite materials, presses them into shape, and then vacuum hot presses and sinters them to obtain an alumina-based material with multi-scale particles. The present invention adds Ni3Ti and CuO / SiC composite materials to the alumina matrix, thereby reducing the sintering temperature and improving the compactness of the alumina-based material, thereby improving the mechanical properties of the alumina-based material. Experimental results show that the fracture toughness of the alumina-based material with multi-scale particles obtained by the preparation method provided by the present invention is ≥6.7MPa·m 1 / 2 , flexural strength ≥746.1MPa, microhardness ≥1821HV. DETAILED DESCRIPTION

[0030] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only 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.

[0031] In order to further illustrate the present invention, the following examples are used to explain it in detail. The raw materials used in the following examples and comparative examples of the present invention are all commercially available products.

[0032] Example 1

[0033] The method for preparing the alumina-based material with multi-scale particles of this embodiment comprises the following steps:

[0034] (1) Ni metal powder (75 μm) and Ti metal powder (75 μm) with a mass ratio of 4:1 were poured into a ball mill and the rotation speed was set to 550 r / min. The ball milling was carried out in an argon atmosphere for 35 h. The powder obtained by ball milling was placed in a vacuum sintering furnace and the vacuum degree was set to 10 -2 Pa, heated to 800 ° C, and kept warm for 2 h to obtain Ni3Ti intermetallic compound powder.

[0035] (2) Take 20 g of SiC whiskers with a length of 50 μm and an aspect ratio of 10:1 and add them to 500 mL of CuSO4 solution (0.6 mol / L). Stir at 200 r / min to fully mix the SiC whiskers and the CuSO4 solution. Then add 40 g of NaOH to the system and stir at 200 r / min. Filter the precipitate and heat the precipitate at 150°C for 10 h to obtain SiC whiskers with CuO coated on the surface.

[0036] (3) 70 g of Al2O3 powder, 10 g of the product obtained in step (1) and 20 g of the product obtained in step (2) were fully mixed at 1000 r / min, and pressed into a cake blank by a press at a pressure of 4 MPa. The cake blank was then subjected to vacuum hot pressing sintering with a vacuum degree of 10 kPa. The temperature was first increased to 300°C at a heating rate of 40°C / min and kept at this temperature for 25 min. The temperature was then increased to 1700°C at a heating rate of 20°C / min and kept at this temperature for 30 min. After the sintering was completed, the product was cooled to room temperature to obtain an alumina-based material with multi-scale particles.

[0037] Example 2

[0038] The only difference between this embodiment and embodiment 1 is that in step (3) of this embodiment, 70 g of Al2O3 powder, 20 g of the product obtained in step (1) and 10 g of the product obtained in step (2) are mixed thoroughly at 1000 r / min, and then pressed and vacuum hot-pressed; the remaining steps and experimental parameters are carried out according to those in embodiment 1.

[0039] Example 3

[0040] The only difference between this embodiment and embodiment 1 is that in step (3) of this embodiment, 70 g of Al2O3 powder, 15 g of the product obtained in step (1) and 15 g of the product obtained in step (2) are fully mixed under the condition of 1000 r / min, and then pressed and vacuum hot-pressed; the remaining steps and experimental parameters are carried out according to those in embodiment 1.

[0041] Comparative Example 1

[0042] The only difference between this comparative example and Example 1 is that step (1) is omitted in this comparative example; in step (3), 70 g of Al2O3 powder, 8 g of Ni metal powder (75 μm), 2 g of Ti metal powder (75 μm) and 20 g of the product obtained in step (2) are directly mixed at 1000 r / min, and then pressed and sintered by vacuum hot pressing; the remaining steps and experimental parameters are carried out according to those in Example 1.

[0043] Comparative Example 2

[0044] The only difference between this comparative example and Example 1 is that step (2) is omitted in this comparative example; in step (3), 70 g of Al2O3 powder, 10 g of the product obtained in step (1), 12 g of SiC whiskers and 8 g of CuO are directly mixed at 1000 r / min, and then pressed and sintered by vacuum hot pressing; the remaining steps and experimental parameters are carried out according to those in Example 1.

[0045] Comparative Example 3

[0046] The difference between this comparative example and Example 1 is that in step (3) of this comparative example, the conditions for vacuum hot pressing sintering of the cake blank are changed to: first, heating to 200°C at a heating rate of 40°C / min, keeping warm for 25 minutes, then heating to 1700°C at a heating rate of 20°C / min, and keeping warm for 30 minutes; the remaining steps and experimental parameters are carried out according to those in Example 1.

[0047] Comparative Example 4

[0048] The only difference between this comparative example and Example 1 is that in step (3) of this comparative example, the conditions for vacuum hot pressing sintering of the cake blank are changed to: directly heating the temperature to 1700°C at a heating rate of 40°C / min and keeping the temperature for 30 minutes; the remaining steps and experimental parameters are carried out according to those in Example 1.

[0049] Test Example 1

[0050] This test example tests the performance of the alumina-based materials obtained in the examples and comparative examples, wherein the fracture toughness is calculated according to the Niihara formula, the bending strength is calculated according to the GB / T 6569-2006 standard, and the micro-Vickers hardness is calculated according to the international standard ISO6507 / 1-82. The test results are shown in Table 1.

[0051] Table 1

[0052]

[0053] It can be seen from Table 1 that, compared with the comparative example, the alumina-based material obtained in the embodiment of the present invention has higher fracture toughness, flexural strength and microhardness, and has better comprehensive mechanical properties.

[0054] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those 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 will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing an alumina-based material having multi-scale particles, characterized in that: include: Al2O3, Ni3Ti and CuO / SiC composite materials are mixed, pressed and subsequently sintered by vacuum hot pressing to obtain an alumina-based material with multi-scale particles; The vacuum hot pressing sintering specifically includes: Under the condition of vacuum degree ≤10kPa, heat to 300-400℃ at a rate of 40-45℃ / min, keep warm for 25-35min, then heat to 1700-1800℃ at a rate of 20-25℃ / min, keep warm for 30-40min; The preparation method of the CuO / SiC composite material comprises: SiC whiskers are mixed with CuSO4 solution and NaOH, and after reaction, a precipitate is obtained by filtering, and the precipitate is heated at a temperature of 150-180° C. to obtain a CuO / SiC composite material.

2. The method for preparing an alumina-based material having multi-scale particles according to claim 1, characterized in that: The mass ratio of the Al2O3, Ni3Ti and CuO / SiC composite material is 70:(10-20):(10-20).

3. The method for preparing an alumina-based material having multi-scale particles according to claim 1, characterized in that: The pressure of the compression molding is 4-5 MPa.

4. The method for preparing an alumina-based material having multi-scale particles according to claim 1, characterized in that: The molar ratio of the SiC whisker to the copper ions in the CuSO4 solution is 1:(1.5-2.5).

5. The method for preparing an alumina-based material having multi-scale particles according to claim 1, characterized in that: The length of the SiC whisker is 40-50 μm, and the aspect ratio is 10:

1.

6. The method for preparing an alumina-based material having multi-scale particles according to claim 1, characterized in that: The preparation method of Ni3Ti comprises: Ni and Ti are mixed and placed in a vacuum of 10 -2 Pa, heated to 800-850°C and kept warm for 1-3h to obtain Ni3Ti.

7. The method for preparing an alumina-based material having multi-scale particles according to claim 6, characterized in that: The mass ratio of Ni to Ti is (3-5):

1.

8. The method for preparing an alumina-based material having multi-scale particles according to claim 6, characterized in that: The particle size of the Ni is 75 μm; the particle size of the Ti is 75 μm.

9. Alumina-based material with multi-scale particles obtained by the method for preparing an alumina-based material with multi-scale particles according to any one of claims 1 to 8.

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