Preparation method of high-quality molybdenum-titanium-based max phase ceramic

Abstract

The application belongs to the field of ceramic preparation, and specifically provides a preparation method of high-quality molybdenum-titanium-based MAX phase ceramic, to solve the problem of low purity of alloy residual samples in the existing preparation method. In the application, first, Ti2AlC ceramic is used as a reaction substrate, and corresponding proportions of molybdenum powder, aluminum powder and carbon powder are uniformly mixed and then subjected to pressureless sintering; then the sintered product is crushed, sieved, ball milled, secondarily sieved, fully reacted with dilute hydrochloric acid, and the reaction product is washed to remove residual hydrochloric acid, titanium salt and aluminum salt; finally, the molybdenum-titanium-based MAX phase ceramic is obtained by drying. Based on this, by using the preparation method provided by the application, a large number of pores can be avoided during the reaction process, the aluminum-molybdenum alloy is fully reacted to form the target product, the purity of the product is greatly improved, and thus the high-quality molybdenum-titanium-based MAX phase ceramic material is obtained.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of ceramic preparation, and relates to preparation of molybdenum-titanium-based MAX phase ceramics, and particularly provides a preparation method of high-quality molybdenum-titanium-based MAX phase ceramics. BACKGROUND

[0002] MAX phase is a new type of nanometer layered ceramic material, and the chemical general formula of the classic MAX phase is M N+1 AX N wherein M represents a transition metal, A represents a main group element, X represents a carbon element or a nitrogen element, and N is a positive integer representing the number of layers of the MAX phase; the MAX phase ceramic not only has the high-temperature resistance (up to 2300 DEG C) and high mechanical strength characteristics of ceramics, but also has the high electrical conductivity and thermal conductivity of metals, and they are applied to the environment and energy fields as heat shock resistant refractory materials, coating layers for electrical contact, neutron radiation resistant components for nuclear applications, etc. due to excellent performance.

[0003] In a conventional preparation method of molybdenum-titanium-based MAX phase ceramics, elemental powders such as molybdenum powder, titanium powder, aluminum powder, and carbon powder are first mixed uniformly, and then subjected to pressureless sintering in a high-temperature tube furnace to obtain the product, as described in the literature "B. Anasori, M. Dahlqvist, J. Halim, E. J. Moon, J. Lu, B. C. Hosler, E. N. Caspi, S. J. May, L. Hultman, P. Eklund, J. Rosen, M. W. Barsoum, Journal of Applied Physics 2015, 118, 094304." However, during the formation of TiAl alloy from titanium powder and aluminum powder, the different diffusion rates thereof generate a large number of pores, and aluminum-molybdenum alloy (AlMo3, an important transition phase of MAX phase) fills in the pores, resulting in a significant reduction in the contact area between AlMo3 and carbide, and thus limiting the reaction, as described in detail in the literature "J. Yang, Y. Wen, X. Li, Y. Fan, H. Zou, C. Zhang, L. Xiong, Y. Liu, Journal of Asian Ceramic Societies 2022, 10, 120." Furthermore, at high temperatures, titanium powder and aluminum powder are more likely to react to form TiC (because TiC has a lower Gibbs free energy), thereby inhibiting the generation of AlMo3 to form Mo2TiAlC2 (MAX phase, target product), as described in detail in the literature "J. Yang, C. Liao, J. Wang, Y. Jiang, Y. He, Ceramics International 2014, 40, 4643." In addition, part of the aluminum-molybdenum alloy remains and cannot be removed by acid washing, and the alloy also hinders the further processing of the product, for example, in the etching process for preparing two-dimensional transition metal carbide, the alloy wrapped on the surface of the MAX phase particles affects the full reaction with hydrofluoric acid. Therefore, the existing preparation method of molybdenum-titanium-based MAX phase ceramics needs to be improved. SUMMARY

[0004] The purpose of the present application is to provide a preparation method of high-quality molybdenum-titanium-based MAX phase ceramics to solve the problems of low sample purity caused by residual alloy in the existing preparation method.

[0005] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0006] A preparation method of high-quality molybdenum-titanium-based MAX phase ceramics, comprising the following steps:

[0007] Step 1: using Ti2AlC powder, molybdenum powder, aluminum powder, and carbon powder as raw materials, and performing one-time ball milling according to the molar ratio Ti2AlC:Mo:Al:C = 1:4.4:1.5:3 to obtain mixed powder;

[0008] Step 2, place the mixed powder in an alumina crucible and then put it into a high-temperature tube furnace, heat it at 1600°C for 4-8 hours in an argon atmosphere, and obtain a sintered material;

[0009] Step 3, use a crusher to crush the sintered material and perform a first sieving, then perform a second sieving after secondary ball milling of the obtained powder, and obtain an intermediate product;

[0010] Step 4, add the powder intermediate to dilute hydrochloric acid under magnetic stirring, the concentration of the dilute hydrochloric acid is 6-9 mol / L, 8-10 ml of dilute hydrochloric acid corresponds to 1 gram of powder product, and a reaction solution is obtained after 24-48 hours of reaction;

[0011] Step 5, use a vacuum filtration device to filter the reaction solution, and then wash with deionized water to obtain the reaction product;

[0012] Step 6, place the reaction product in a vacuum drying oven and dry it at 80-120°C for 8-24 hours to obtain the target product.

[0013] Further, in step 1, the primary ball milling process is as follows: 4-8 mm zirconia balls are used as the ball milling medium, the raw material and the zirconia balls are placed in the ball mill tank according to a mass ratio of 1:2-1:4, and the ball mill is operated at a speed of 80-300 rpm for 18-24 hours to obtain the mixed powder.

[0014] Further, in step 2, the temperature rising and falling speed is 3-5°C / min, and the argon flow rate is 50-100 sccm.

[0015] Further, in step 3, the speed of the crusher is 20,000-28,000 rpm.

[0016] Further, in step 3, the first sieving uses a 200 mesh standard sieve, and the second sieving uses a 400 mesh standard sieve.

[0017] Further, in step 3, the secondary ball milling process is as follows: 4-8 mm zirconia balls are used as the ball milling medium, the raw material and the zirconia balls are placed in the ball mill tank according to a mass ratio of 1:2-1:4, and the ball mill is operated at a speed of 80-300 rpm for 18-24 hours to obtain the powder product.

[0018] Further, in step 4, the speed of the magnetic rotor stirring is 250-400 rpm.

[0019] Further, in step 5, the deionized water is washed until the pH of the solution after washing is 6-7 to remove residual hydrochloric acid, titanium salt and aluminum salt.

[0020] Based on the above technical solutions, the beneficial effects of the present application are as follows:

[0021] The application provides a preparation method of high-quality molybdenum-titanium-based MAX phase ceramic, which comprises the following steps: taking Ti2AlC ceramic as a reaction substrate, uniformly mixing molybdenum powder, aluminum powder and carbon powder and the like in a corresponding proportion, and then performing pressureless sintering, and the preparation method is specifically shown as follows:

[0022] 4.4Mo+1.5Al+3C+Ti2AlC=>2Mo2TiAlC2

[0023] The method can avoid a large number of pores generated in the reaction process, the aluminum-molybdenum alloy is fully reacted to generate a target product, the purity of the product is greatly improved, and thus the high-quality molybdenum-titanium-based MAX phase ceramic material can be obtained. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 FIG. 1 is an X-ray diffraction pattern of a Mo2TiAlC2 ceramic sample prepared in the example 1 and the comparative example of the application.

[0025] Figure 2 FIG. 2 is a scanning electron microscope (SEM) image of a Mo2TiAlC2 ceramic sample prepared in the example 1 and the comparative example of the application. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical scheme and beneficial effects of the application clearer, the application is further described in detail below with reference to the drawings and examples.

[0027] Example 1

[0028] The example provides a preparation method of high-quality molybdenum-titanium-based MAX phase ceramic, and the preparation target is 8g Mo2TiAlC2 ceramic, and the specific steps are as follows:

[0029] Step 1. 5.33g of molybdenum powder, 0.51g of aluminum powder, 0.46g of carbon powder and 1.7g of Ti2AlC powder are used as raw materials, 8mm zirconia balls are used as ball milling media, the raw materials and 16g of zirconia balls are placed in a ball milling tank, the ball milling speed is set to 150rpm, and the mixed powder is obtained after mixing for 18 hours;

[0030] Step 2. The mixed powder is placed in a 6cm*4cm alumina crucible and then placed in a high-temperature furnace, and then sintered at 1600℃ for 4 hours under an argon atmosphere, and then a sintered material is obtained; wherein the temperature rising and falling speed is 3℃ / min, and the argon flow rate is 100sccm;

[0031] Step 3, after the sintered material is crushed at a rotation speed of 28000 rpm using a crusher, the sintered material is filtered using a 200 mesh (less than 75 μm) standard sieve; then 8 mm zirconia balls are used as the ball milling medium, the powder and 24 g of the zirconia balls are placed in a ball mill jar, the ball milling speed is set to 300 rpm, and the powder is ball milled for 24 hours; then the powder is filtered again using a 400 mesh (less than 38 μm) standard sieve, and 7.6 g of the powder is obtained;

[0032] Step 4, the powder is added into 70 ml of dilute hydrochloric acid with a concentration of 9 mol / l under a stirring speed of 400 rpm, and the reaction is performed for 24 hours to obtain a reaction solution;

[0033] Step 5, the reaction solution is filtered using a vacuum filtration device to obtain a reaction product, and the reaction product is washed using 2 L of deionized water;

[0034] Step 6, the reaction product is placed in a vacuum drying oven, the temperature is set to 80℃, and the reaction product is dried for 8 hours to obtain 7.2 g of a Mo2TiAlC2 ceramic sample.

[0035] As can be seen, the production ratio of the Mo2TiAlC2 ceramic sample in this embodiment is 90%; further tests are performed on the Mo2TiAlC2 ceramic sample, as shown in Figure 1 which is an X-ray diffraction pattern, and as can be seen, compared with the traditional method, not only is the 9.46° (002) peak greatly enhanced, but also the alloy phase impurity peak of 41.48° AlMo3 has disappeared, that is, the purity and quality of the Mo2TiAlC2 are greatly improved; as shown in Figure 2 which is a scanning electron microscope image, and as can be seen, compared with the traditional method, the alloy phase (aluminum molybdenum alloy) does not occur, and a clear layered structure is exhibited.

[0036] Embodiment 2

[0037] This embodiment provides a method for preparing a high-quality molybdenum-titanium-based MAX phase ceramic, and the preparation target is 10 g of a Mo2TiAlC2 ceramic, and the specific steps are as follows:

[0038] Step 1, 6.67 g of molybdenum powder, 0.64 g of aluminum powder, 0.56 g of carbon powder, and 2.13 g of Ti2AlC powder are used as raw materials, 4 mm zirconia balls are used as the ball milling medium, the raw materials and 30 g of the zirconia balls are placed in a ball mill jar, the ball milling speed is set to 120 rpm, and the mixture is mixed for 24 hours to obtain a mixed powder;

[0039] Step 2, the mixed powder is placed in a 6 cm x 4 cm alumina crucible and then placed in a high-temperature furnace, and the mixed powder is sintered at 1600℃ for 8 hours under an argon atmosphere; wherein the temperature rising and falling speed is 3℃ / min, and the argon flow rate is 80 sccm;

[0040] Step 3, after the sintered material is crushed at a rotating speed of 20000 rpm using a crusher, the material is filtered using a 200 mesh standard sieve; then 8mm zirconia balls are used as the ball milling medium, the powder and 30g zirconia balls are placed in a ball mill bottle, the ball milling speed is set to 350rpm, and after ball milling for 18 hours, the powder is filtered again using a 400 mesh standard sieve, and 9.5g powder is obtained;

[0041] Step 4, the powder is added to 90ml of 9mol / l concentrated hydrochloric acid at a stirring speed of 400rpm, and the reaction is carried out for 24 hours to obtain a reaction solution;

[0042] Step 5, the reaction solution is filtered using a vacuum filtration device to obtain a reaction product, and the reaction product is washed using 4L deionized water;

[0043] Step 6, the reaction product is placed in a vacuum drying oven, the temperature is set to 120℃, and after drying for 18 hours, 9.2g of Mo2TiAlC2 ceramic is obtained, and the production ratio is 92%.

[0044] The above is only a specific embodiment of the present application, any feature disclosed in the specification can be replaced by other equivalent or similar purpose alternative features unless specifically described; all features disclosed, or steps in all methods or processes, except for mutually exclusive features and / or steps, can be combined in any way.

Claims

1. A method for preparing high-quality molybdenum-titanium based MAX phase ceramics, characterized in that, The method comprises the following steps: Step 1, using Ti2AlC powder, molybdenum powder, aluminum powder and carbon powder as raw materials, and performing one-time ball milling according to the molar ratio of Ti2AlC:Mo:Al:C=1:4.4:1.5:3 to obtain mixed powder; Step 2, placing the mixed powder in an alumina crucible and then into a high-temperature tube furnace, and performing heat preservation at 1600 DEG C for 4-8 hours under an argon atmosphere to obtain sintered material; Step 3, crushing the sintered material using a crusher and performing first screening, and then performing second screening after secondary ball milling to obtain an intermediate product; Step 4, adding the intermediate product into dilute hydrochloric acid under magnetic stirring, the concentration of the dilute hydrochloric acid is 6-9 mol / L, 8-10 ml of dilute hydrochloric acid corresponds to 1 gram of powder product, and a reaction solution is obtained after reacting for 24-48 hours; Step 5, performing solution filtration on the reaction solution using a vacuum filtration device to obtain a reaction product and washing with deionized water; Step 6, placing the reaction product into a vacuum drying box and drying at 80-120 DEG C for 8-24 hours to obtain a target product.

2. The method of claim 1, wherein the high-quality Mo-Ti-based MAX phase ceramic is prepared by the following steps of: In step 1, the one-time ball milling process is as follows: 4-8 mm zirconia balls are used as ball milling media, the raw materials and the zirconia balls are placed in a ball mill tank according to a mass ratio of 1:2-1:4, and ball milling is performed in a ball mill at a rotating speed of 80-300 rpm for 18-24 hours to obtain the mixed powder. ​ 3. The method of claim 1, wherein the high-quality Mo-Ti-based MAX phase ceramic is prepared by the following steps of: (a) preparing a Mo-Ti-based MAX phase ceramic precursor; (b) sintering the Mo-Ti-based MAX phase ceramic precursor to obtain the Mo-Ti-based MAX phase ceramic. In step 2, the temperature rising and falling speed is 3-5 DEG C / min, and the argon flow rate is 50-100 sccm.

4. The method of claim 1, wherein the high-quality Mo-Ti-based MAX phase ceramic is prepared by the following steps of: (a) preparing a Mo-Ti-based MAX phase ceramic precursor; (b) sintering the Mo-Ti-based MAX phase ceramic precursor to obtain the Mo-Ti-based MAX phase ceramic. In step 3, the rotating speed of the crusher is 20000-28000 rpm.

5. The method for preparing high-quality molybdenum-titanium-based MAX phase ceramics according to claim 1, characterized in that, In step 3, 200 mesh standard sieve is used for the first screening, and 400 mesh standard sieve is used for the second screening.

6. The method for preparing high-quality molybdenum-titanium-based MAX phase ceramics according to claim 1, characterized in that, In step 3, the secondary ball milling process is as follows: 4-8 mm zirconia balls are used as ball milling media, the raw materials and the zirconia balls are placed in a ball mill tank according to a mass ratio of 1:2-1:4, and ball milling is performed in a ball mill at a rotating speed of 80-300 rpm for 18-24 hours to obtain the powder product.

7. The method for preparing high-quality molybdenum-titanium-based MAX phase ceramics according to claim 1, characterized in that, In step 4, the rotating speed of the magnetic rotor stirring is 250-400 rpm.

8. The method for preparing high-quality molybdenum-titanium-based MAX phase ceramics according to claim 1, characterized in that, In step 5, the deionized water is washed until the ph of the solution after washing is 6-7.

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