Ultrafast preparation method of MAX phase material

Abstract

The invention relates to a preparation method of an MAX phase material. According to the specific technical scheme, precursor powder materials needed for preparing the MAX phase material are mixed to obtain mixed powder, the mixed powder is subjected to mechanical ball milling and cold press forming to form a blank, a to-be-sintered blank is obtained, the to-be-sintered blank is subjected to ultra-fast Joule hot sintering, and the MAX phase material is prepared. The MAX phase material is prepared by using an ultra-fast Joule thermal sintering method, the Joule thermal sintering method has the characteristics of high heating and cooling rate (104 DEG C / min) and high heating temperature (3000 DEG C), and according to the Arrhenius formula, the synthesis rate of the MAX phase material can be greatly improved due to the characteristics of high heating and cooling rate and high heating temperature, and rapid preparation of the MAX phase material is realized. According to the method, the preparation period of the MAX phase material can be greatly shortened, so that the aging can be improved, the energy consumption can be reduced, accurate and controllable preparation can be realized, and the method has important significance on low-cost and large-scale preparation of the MAX phase material.

Description

Technical Field

[0001] The present invention relates to the field of inorganic non-metallic materials, and particularly relates to a preparation method of MAX phase materials. Background Art

[0002] MAX phase materials are layered inorganic non-metallic materials composed of transition metal carbides / nitrides and A atomic layers, and their chemical formula is Mn+1AXn (n = 1-3), where M represents a pre-transition metal element, A represents elements in groups IIIA and IVA, and X is carbon or nitrogen. Due to its unique hybrid bonds (ionic bonds, covalent bonds, and metallic bonds) and layered structure, MAX phase materials themselves have excellent ductility and processability, electrical and thermal conductivity, high melting point, high strength, corrosion resistance, oxidation resistance and other excellent properties, making them show application potential in many fields. And two-dimensional MXenes materials derived from MAX phase materials as precursors also show good application prospects in many fields such as energy storage and conversion, environment, and biomedicine due to their many excellent intrinsic properties such as metallic conductivity, hydrophilicity, biocompatibility, redox ability, catalytic activity, light transmittance, antibacterial property, and tunable plasmon resonance.

[0003] The traditional synthesis methods of MAX phase materials mainly rely on high-temperature solid-state reactions, which must be carried out under the protection of an inert atmosphere. The reaction temperature is usually between 1100°C and 1700°C, and the reaction time is several hours or even more than ten hours. The long-term high-temperature reaction not only has low energy and time efficiency, which is not conducive to the low-cost and large-scale preparation of MAX phase materials, but also causes the following problems: (1) It causes the loss of volatile elements (such as Al, Si), and it is impossible to accurately control the stoichiometric ratio of each element in the MAX phase; (2) It causes the formation of thermodynamically stable second-phase by-products (such as carbides, nitrides, intermetallic compounds), and it is difficult to obtain high-purity MAX phase materials; (3) It causes grain coarsening, affecting the microstructure and mechanical properties of MAX. In recent years, researchers have developed a variety of new technologies for the preparation of MAX phase materials to solve the problems faced by traditional preparation methods. For example, self-propagating high-temperature synthesis (SHS), spark plasma sintering (SPS), physical vapor deposition (PVD), chemical vapor deposition (CVD). Although the above methods have successfully shortened the preparation cycle of MAX phase, they also have their own unavoidable disadvantages: the reaction process of high-temperature self-propagating synthesis (SHS) is uncontrollable, and it is difficult to achieve precise control of the structure and properties of MAX phase materials; in the process of spark plasma sintering (SPS), a mold is required to apply pressure to the sintered material, and it is impossible to prepare special-shaped parts and impossible to achieve batch preparation; while vapor deposition methods (PVD, CVD) can only be used to prepare MAX phase thin films or coatings, and cannot be used to prepare bulk MAX phase materials.

[0004] In summary, the existing MAX phase material preparation technologies mainly have the following problems:

[0005] 1. Due to the long-time high-temperature heating in the traditional preparation methods of MAX phase materials, the energy and time efficiency are low; it is impossible to accurately control the stoichiometric ratio of each element; it is difficult to obtain high-purity MAX phase materials; and the grain coarsening affects the microstructure and mechanical properties.

[0006] 2. The new preparation technologies of MAX phase materials have their respective limitations, such as the uncontrollable preparation process, over-reliance on pressure sintering, difficulty in preparing special-shaped parts, and difficulty in realizing batch preparation, etc. Summary of the Invention

[0007] In view of this, the present invention provides an ultra-fast preparation method for MAX phase materials. The main purpose is to realize the rapid preparation of MAX phase materials with a simple process, and solve the problems of the long preparation cycle of traditional MAX phase materials and the resulting difficulty in accurately and controllably preparing MAX phase materials.

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] An ultra-fast preparation method for MAX phase materials, comprising the following steps:

[0010] Powder mixing step:

[0011] Mix the precursor powders required for preparing MAX phase materials according to the stoichiometric ratio of each element in the MAX chemical formula to obtain a mixed powder, and obtain a uniformly mixed precursor powder after mechanical ball milling and drying of the mixed powder;

[0012] Green body forming step:

[0013] Press the uniformly mixed precursor powder into a green body to be sintered by using a green body forming method;

[0014] Sintering step:

[0015] Place the green body to be sintered in a self-made joule heating sintering device, and under the protection of an inert atmosphere, carry out rapid high-temperature sintering on the green body at a certain sintering temperature, and naturally cool down after sintering to obtain a MAX phase bulk material;

[0016] Grinding step:

[0017] The obtained MAX phase bulk material can be ground to obtain a MAX phase powder material.

[0018] 1. According to the embodiment of the present invention, the precursor powder is TiC, Al, Ti; preferably, the particle size of the precursor powder is below 38 μm.

[0019] 2. According to the embodiments of the present invention, the stoichiometric ratio of the precursor powder is TiC:Al:Ti = (1-2):(1-1.2):(1-1.2).

[0020] 3. According to the embodiments of the present invention, the mechanical ball milling method can be wet ball milling or dry ball milling. Preferably, the mechanical ball milling method uses wet ball milling with absolute ethanol as the ball milling medium. Preferably, the mass ratio of the powder, ball milling beads and absolute ethanol during mechanical ball milling is 1:2:0.6.

[0021] 4. According to the embodiments of the present invention, the mechanical ball milling rate is 200-500 r / min, and the ball milling time is more than 6 h.

[0022] 5. According to the embodiments of the present invention, the drying process can be carried out by a method known in the art; preferably, vacuum drying is used for drying, the drying temperature is 30-60 °C, and the drying time is more than 6 h.

[0023] 6. According to the embodiments of the present invention, the billet forming method includes cold pressing, extrusion molding, and gel casting. Preferably, the billet forming method is cold pressing to form a billet, the applied pressure is 2-20 Mpa, the pressure holding time is more than 30 s, and the mold can be selected from molds known in the art, which is not specifically limited in the present invention.

[0024] 7. According to the embodiments of the present invention, the Joule heat heating medium can be conductive materials such as carbon paper, carbon felt, and carbon fiber. Preferably, the heating medium is carbon felt, and the dimensions are: length 3-30 cm, width 5-100 mm, and thickness 1-10 mm.

[0025] 8. According to the embodiments of the present invention, the Joule heat sintering specifically includes: first, placing the green body to be sintered in the high-temperature area of the Joule heat heating medium, heating to 1400 °C - 1750 °C, then holding for 10-20 s to complete sintering, and finally cooling. Preferably, the heating rate is 10 3 -10 4 °C / min, and the cooling can be selected from cooling methods known in the art, such as natural cooling.

[0026] 9. According to the embodiments of the present invention, in the grinding step, the grinding method can be manual grinding or mechanical grinding. Preferably, manual grinding is used, and the grinding time is more than 30 min.

[0027] The advantages and positive effects of the present invention are:

[0028] 1. The present invention realizes the ultra-fast preparation of MAX phase materials;

[0029] 2. The present invention realizes the precise and controllable preparation of MAX phase materials;

[0030] 3. The technological process of the present invention is simple and has high energy and time efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 XRD pattern of Ti2AlC prepared in Example 1.

[0032] Figure 2 Microscopic morphology diagram of Ti2AlC prepared in Example 1.

[0033] Figure 3 Temperature-time curve for preparing Ti2AlC in Example 1.

[0034] Figure 4 XRD pattern of Ti3AlC2 prepared in Example 2.

[0035] Figure 5 Microscopic morphology diagram of Ti3AlC2 prepared in Example 2.

[0036] Figure 6 Temperature-time curve for preparing Ti3AlC2 in Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0037] The technical solutions of the present invention will be further described below in conjunction with specific embodiments. It should be understood that the following embodiments are only used to exemplarily illustrate the present invention and are not used to limit the protection scope of the present invention. Those skilled in the art can make some non-essential improvements and adjustments based on the content of the above invention, and these are all covered within the scope of the present invention.

[0038] The raw materials and reagents used in the following examples are all commercially available products.

[0039] Example 1

[0040] 1. Powder mixing: Weigh TiC, Al, and Ti powders according to the stoichiometric ratio of 1:1.2:1.2; add the above powders into a zirconia ball milling tank, and add zirconia ball milling beads and anhydrous ethanol according to the mass ratio of powder, ball milling beads, and anhydrous ethanol of 1:2:0.6. Then seal the ball milling tank in a glove box to make it filled with inert protective gas; perform wet ball milling in a ball mill, set the rotation speed to 300 rpm / min, and set the ball milling time to 6 h; transfer the ball-milled mixed slurry to a vacuum drying oven and dry it at 50 °C for 12 h to obtain a uniformly mixed precursor powder.

[0041] 2. Green body forming: Adopt the cold pressing forming method, and keep the pressure at 5 Mpa for 1 min to press the uniformly mixed precursor powder into a green body to be sintered.

[0042] 3. Sintering: Place the above-mentioned green body to be sintered in a self-made Joule heating sintering device. Under the protection of an inert atmosphere, rapidly heat it up to 1600 °C, hold for 20 s, and then naturally cool to obtain a Ti2AlC MAX-phase bulk material.

[0043] 4. Manually grind the Ti2AlC bulk material prepared by Joule heating for 35 min to obtain Ti2AlC powder.

[0044] Example 2

[0045] 1. Powder mixing: Weigh TiC, Al, and Ti powders according to the stoichiometric ratio of 1.8:1.1:1.2; add the above powders into a zirconia ball milling tank. According to the mass ratio of powder, ball milling beads, and absolute ethanol being 1:2:0.6, add zirconia ball milling beads and absolute ethanol, and then seal the ball milling tank in a glove box to make it filled with an inert protective gas; perform wet ball milling in a ball mill, set the rotation speed to 300 rpm / min, and set the ball milling time to 6 h; transfer the ball-milled mixed slurry to a vacuum drying oven and dry it at 50 °C for 12 h to obtain a uniformly mixed precursor powder.

[0046] 2. Green body forming: Adopt the cold pressing forming method, under a pressure of 5 Mpa, hold the pressure for 1 min, and press the uniformly mixed precursor powder into a green body to be sintered.

[0047] 3. Sintering: Place the above-mentioned green body to be sintered in a self-made Joule heating sintering device. Under the protection of an inert atmosphere, rapidly heat it up to 1500 °C, hold for 15 s, and then naturally cool to obtain a Ti3AlC2 MAX-phase bulk material.

[0048] 4. Manually grind the Ti3AlC2 bulk material prepared by Joule heating for 35 min to obtain Ti3AlC2 powder.

[0049] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for ultra-rapid preparation of MAX phase materials, characterized in that The preparation method includes the following steps: Powder mixing step: Mix the precursor powders required for preparing the MAX phase material according to the stoichiometric ratio of each element in the MAX chemical formula to obtain a mixed powder, and obtain a uniformly mixed precursor powder after mechanically ball-milling and drying the mixed powder; Green body forming step: Press the uniformly mixed precursor powder into a green body to be sintered by using a green body forming method; Sintering step: Place the green body to be sintered in a self-made joule heat sintering device, and under the protection of an inert atmosphere, perform rapid high-temperature sintering on the green body at a certain sintering temperature, and naturally cool down after sintering to obtain a MAX phase bulk material; Grinding step: The obtained MAX phase bulk material can be ground to obtain a MAX phase powder material.

2. The ultra-rapid preparation method of the MAX phase material according to claim 1, characterized in that: In the powder mixing step, the precursor powder can be the corresponding single element or compound; preferably, the particle size of the precursor powder is below 38 μm.

3. The ultra-rapid preparation method of the MAX phase material according to claims 1-3, characterized in that: In the powder mixing step, the mechanical ball-milling method can be dry ball-milling or wet ball-milling; preferably, the mechanical ball-milling rate is 200 r / min to 500 r / min, and the ball-milling time is more than 6 h.

4. The ultra-rapid preparation method of the MAX phase material according to claims 1-4, characterized in that: In the powder mixing step, the drying method can be carried out by any known method in the art.

5. The ultra-rapid preparation method of the MAX phase material according to claims 1-5, characterized in that: The green body forming method includes cold pressing, extrusion molding, and gel casting.

6. The ultra-rapid preparation method of the MAX phase material according to claim 1, characterized in that: In the sintering step, the inert atmosphere can be any one of nitrogen, argon, and helium.

7. The ultra-fast preparation method of the MAX phase material according to claim 1, characterized in that: In the sintering step, the heating medium used in the self-made joule heat sintering device can be a conductive material such as carbon paper, carbon felt, and carbon fiber. Preferably, the heating medium used is carbon felt, and the dimensions are as follows: the length is 3 to 30 cm, the width is 5 to 100 mm, and the height is 1 to 10 mm.

8. The ultra-rapid preparation method of the MAX phase material according to claim 1, characterized in that: In the sintering step, the sintering temperature is 1000°C to 2500°C, and the heating and cooling rate is 10 3 ~10 4 °C / min, and the sintering time is 5 to 60 s.

9. The ultra-rapid preparation method of the MAX phase material according to claims 1-8, characterized in that: In the grinding step, the grinding method can be manual grinding or mechanical grinding.

10. A method for ultra-rapid preparation of MAX phase materials, characterized in that, The MAX phase material is prepared by the preparation method according to any one of claims 1-9.

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