A method for preparing a max phase material based on a natural metal mineral

Abstract

The application belongs to the technical field of MAX phase material preparation, and particularly relates to a method for preparing MAX phase material based on natural metal minerals. The method comprises the following steps: mixing natural metal mineral powder, aluminum powder and graphite powder, and then ball milling to obtain activated precursor powder; pressing the activated precursor powder into a dense blank, and synthesizing a block material through self-propagating high-temperature reaction; crushing the block material and sieving to obtain a MAX phase powder material, wherein the natural metal mineral is rutile and / or chromite; and the general formula of the MAX phase powder material is (Ti 1‑x Cr x ) n+1 AlC n , wherein 0<=x<=1, and n is 1 or 2. The method is different from the prior art in reaction principle, realizes cost reduction and greenization of the whole chain of raw materials, synthesis and etching, and solves the problem of mineral impurities by using the instantaneous high-temperature characteristics of SHS.

Description

Technical Field

[0001] This invention belongs to the field of MAX phase material preparation technology, specifically relating to a method for preparing MAX phase materials based on natural metal minerals. Background Technology

[0002] MAX phase materials are a class of ternary carbides or nitrides with a layered structure, and their general formula is M. n+1 AX n (Where M represents a transition metal, A is primarily a group IIIA or IVA element, and X is C or N). These materials combine the excellent properties of both metals and ceramics, such as high toughness, good electrical and thermal conductivity, and excellent high-temperature resistance and oxidation resistance, making them highly promising for applications in high-temperature structural components, electrode materials, and protective coatings. Crucially, the MAX phase can serve as a precursor; by selectively etching the "A" atomic layer, high-performance two-dimensional MXene materials can be further prepared. These materials show broad application prospects in cutting-edge fields such as electrochemical energy storage, electromagnetic shielding, and catalysis. Therefore, achieving efficient and low-cost preparation of MAX phase materials is a key foundation for promoting the large-scale application of MAX phase materials and their derivatives, MXene.

[0003] However, current technologies for preparing high-purity MAX phases face significant bottlenecks. Mainstream methods generally rely on high-purity (typically ≥99.9%) elemental metals (such as Ti powder and Cr powder) or metal carbide powders (such as TiC) as raw materials, and commonly employ traditional high-temperature sintering techniques such as hot pressing and spark plasma sintering. While these methods can yield dense bulk materials, they suffer from extremely high raw material costs, high energy consumption during production, demanding equipment requirements, and long reaction cycles, severely hindering the large-scale, low-cost production and commercial application of MAX phases and their derived MXene materials.

[0004] To reduce raw material costs at the source, the academic community has begun exploring the use of metal oxides to replace high-purity metal powders. For example, TiO2 is an abundant and inexpensive titanium resource. However, directly using metal oxide minerals for MAX phase synthesis faces severe challenges. Traditional preparation methods using metal oxides as raw materials often require strict atmosphere control, and byproducts are easily generated during the reaction, resulting in low purity of the final product, which is particularly difficult to meet the requirements of high-purity applications. In addition, the preparation process is complex, cumbersome, and requires harsh reaction conditions, resulting in high energy consumption and making it difficult to achieve large-scale, low-cost production. When using natural minerals containing multiple impurities (such as chromite, which often contains Fe, Mg, Si, etc.), the impurity control problem is even more prominent, and existing technologies are difficult to solve effectively. Self-propagating high-temperature synthesis technology has significant advantages such as extremely low energy consumption, fast reaction speed (second-level completion), and simple equipment because it utilizes the exothermic reaction itself to maintain the synthesis process. However, when applying SHS technology to MAX phase synthesis, most existing technologies use elemental metals or metal carbides (such as TiC) as raw materials, and the reaction mechanism is a direct chemical combination reaction between elemental metals. In contrast, using metal minerals as raw materials involves a more complex aluminothermic reduction reaction process.

[0005] In conclusion, developing a complete technology capable of directly synthesizing high-purity MAX phase materials from natural metal minerals through an efficient and energy-saving synthetic route is both urgently needed and of significant value. This would not only revolutionize the reduction of raw material and manufacturing costs for MAX phases and their downstream MXene materials, but also provide a new technological route for the development of high-performance materials based on abundant elements. Summary of the Invention

[0006] The technical problem this invention aims to solve is to address the series of shortcomings in existing technologies for preparing MAX phases and MXenes, such as high raw material costs, high energy consumption during synthesis, and dangerous and costly etching processes. This invention provides an integrated method for in-situ preparation of MAX phases using inexpensive natural metal minerals as initial raw materials and innovatively employing aluminothermic reduction coupled with self-propagating high-temperature synthesis (Aluminothermic SHS) technology. This method differs from existing technologies in its reaction principle, achieving cost reduction and greening of the entire chain from raw materials to synthesis and etching, and utilizing the instantaneous high-temperature characteristics of SHS to solve the problem of mineral impurities.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0008] The first aspect of this invention provides a method for preparing MAX phase materials based on natural metal minerals, comprising the following steps:

[0009] S1. Natural metal mineral powder, aluminum powder and graphite powder are mixed and ball-milled to obtain activated precursor powder;

[0010] S2. The activated precursor powder is pressed into a dense preform and placed in a self-propagating high-temperature reaction device. Under an inert protective atmosphere, the synthesis reaction is triggered by local tungsten wire heating and ignition to obtain bulk material.

[0011] S3. After crushing the bulk material, sieve it to obtain the MAX phase powder material;

[0012] The natural metallic mineral is rutile and / or chromite; the MAX phase powder material has the general formula (Ti 1- x Cr x ) n+1 AlC n , where 0≤x≤1, and n is 1 or 2.

[0013] In S1, the ball milling process conditions are as follows: time is 4 to 12 hours, ball-to-material ratio is (4 to 5): 1, and rotation speed is 200 to 300 rpm.

[0014] In some embodiments of the present invention, in S1, the ball milling process conditions are: time of 6 hours, ball-to-material ratio of 4:1, and rotation speed of 240 rpm.

[0015] In S2, the blank is cylindrical with a diameter of 5 cm and its height is adjusted according to the amount of material to be prepared.

[0016] In some embodiments of the present invention, in S2, the blank is cylindrical with a diameter of 5 cm and a height of 1 to 1.5 cm.

[0017] In S3, the crushing process is carried out under the following conditions: time is 2 hours, ball-to-material ratio is 5:1, and rotation speed is 400 rpm.

[0018] In some embodiments of the present invention, the MAX phase powder material includes Ti2AlC, Ti3AlC2, Cr2AlC and (Ti 1 / 2 Cr 1 / 2 Any one of )2AlC.

[0019] In some embodiments of the present invention, when the MAX phase powder material is Ti2AlC or Ti3AlC2, in S1, the molar ratio of each element in the activated precursor powder is Ti:Al:C = (2~3):(3.5~5.5):(1~2).

[0020] In some embodiments of the present invention, when the MAX phase powder material is Cr2AlC, in S1, the molar ratio of each element in the activated precursor powder is Cr:Al:C = 2:(2.5~3.5):1.

[0021] In some embodiments of the present invention, when the MAX phase powder material is (Ti 1 / 2 Cr 1 / 2 In S1, when 2AlC is used, the molar ratio of each element in the activated precursor powder is Ti:Cr:Al:C = 1:1:(2.5~4):1.

[0022] Specifically, the amount of aluminum powder used must simultaneously meet the stoichiometric requirements for reducing TiO2 to elemental Ti or reducing Cr oxide in chromite to synthesize the MAX phase with Ti or Cr and C.

[0023] A second aspect of the present invention provides a MAX phase material.

[0024] In some embodiments of the present invention, MAX phase materials were successfully prepared by the preparation method of the first aspect of the present invention. Further characterization showed that the XRD patterns of the prepared materials were consistent with standard spectra. Figure One The target phase was successfully synthesized, and the material exhibits obvious layered structure characteristics.

[0025] A third aspect of the present invention provides an application of MAX phase materials in the preparation of MXene materials.

[0026] In some embodiments of the present invention, MXene materials were successfully synthesized by further processing the prepared MAX phase materials. Further characterization revealed that the materials exhibited a typical two-dimensional nanosheet stacked morphology, and the MXene accordion-like structure was clearly defined. This demonstrates the application prospects of the MAX phase materials provided by the present invention in the preparation of MXene materials.

[0027] In some embodiments of the present invention, the MXene material is prepared by an in-situ etching system of HCl / LiF. By controlling the reaction temperature and concentration, the etching rate and depth can be effectively controlled, which is beneficial to obtaining MXene materials with complete structure and suitable surface functional groups.

[0028] Beneficial effects:

[0029] 1. Reduced raw material costs: The use of abundant and inexpensive natural rutile and chromite to completely replace high-purity titanium powder and chromium powder reduces the raw material cost of MAX phase precursors by more than an order of magnitude, clearing the primary obstacle to the large-scale and low-cost application of MXene materials.

[0030] 2. The synthesis process is highly efficient and energy-saving, with in-situ purification capabilities: It innovatively couples the aluminothermic reduction reaction with SHS technology in situ, utilizing the intense exothermic reaction of aluminum reducing oxides as the sole energy source for synthesizing the MAX phase, achieving "reaction fueling reaction." This process boasts extremely low energy consumption, extremely fast reaction speeds (on the order of seconds), and simple equipment. More importantly, the instantaneous ultra-high temperature of SHS effectively volatilizes or decomposes impurities such as SiO2 and Fe2O3 in the minerals, achieving in-situ purification during the synthesis process and solving the technical challenge of ensuring purity when using inexpensive minerals as raw materials.

[0031] 3. Safe, economical, and controllable etching process: This method abandons the traditional, dangerous direct etching method using high-concentration hydrofluoric acid and instead employs a buffer etching strategy that generates the etchant in situ using HCl / LiF. This method provides mild etching conditions and a controllable etching rate, significantly reducing safety risks, equipment corrosion risks, and wastewater treatment costs. Furthermore, it is more conducive to obtaining MXene materials with intact structures and excellent surface chemistry, thereby improving their application performance.

[0032] 4. Complete and highly scalable technology chain: This invention forms a complete, closed-loop material preparation technology chain from basic minerals to high-end two-dimensional nanomaterials. The processes are interconnected, and each link has the potential for engineering scale-up, providing a practical and feasible new path for the low-cost, mass production of MXene family materials, with broad application prospects. Attached Figure Description

[0033] The present invention will be further described in detail below with reference to the accompanying drawings, and the advantages of the present invention in the above and / or other aspects will become clearer.

[0034] Figure 1 The image shows the XRD pattern of the Ti2AlC MAX phase material prepared in Example 1 of this invention.

[0035] Figure 2 This is a SEM image of the Ti2AlC MAX phase material prepared in Example 1 of the present invention.

[0036] Figure 3 The image shows the XRD pattern of the Ti3AlC2 MAX phase material prepared in Example 2 of this invention.

[0037] Figure 4 This is a SEM image of the Ti3AlC2 MAX phase material prepared in Example 2 of the present invention.

[0038] Figure 5 The image shows the XRD pattern of the Cr2AlC MAX phase material prepared in Example 3 of this invention.

[0039] Figure 6This is a SEM image of the Cr2AlC MAX phase material prepared in Example 3 of the present invention.

[0040] Figure 7 The image shows the XRD pattern of Ti3C2 MXene material prepared by in-situ etching of Ti3AlC2 in Example 5 of this invention.

[0041] Figure 8 This is a SEM image of the Ti3C2 MXene material prepared by in-situ etching of Ti3AlC2 in Example 5 of the present invention.

[0042] Figure 9 The image shows the XRD pattern of Ti3AlC2 prepared by the conventional high-temperature sintering process in the comparative example of this invention. Detailed Implementation

[0043] The present invention will be further described in detail below with reference to specific embodiments, and the advantages of the present invention in the above and / or other aspects will become clearer.

[0044] Unless otherwise specified, the experimental methods described in the following examples are conventional methods; unless otherwise specified, the reagents and materials are commercially available.

[0045] Example 1:

[0046] This embodiment provides a one-step method for preparing Ti2AlC MAX phase materials using natural rutile as the titanium source and through aluminothermic reduction reaction coupled with self-propagating high-temperature synthesis (SHS) technology. The specific preparation steps are as follows:

[0047] S1. First, precise calculations were performed based on the stoichiometric ratio of the target product Ti2AlC (Ti:Al:C=2:1:1) and the chemical equation for the aluminothermic reduction reaction (3TiO2+4Al→3Ti+2Al2O3) (taking the preparation of 20g of Ti2AlC material as an example). Natural rutile powder (TiO2 content ≥90wt%, 100 mesh), aluminum powder (purity 99.5%, 300 mesh), and graphite powder (purity 99.9%, 300 mesh) were weighed and mixed according to a molar ratio of Ti:Al:C=2:3.5:1. The above raw materials were placed in a planetary ball mill jar and ball-milled for 6 hours under high-purity argon protection at a ball-to-material mass ratio of 4:1 and a rotation speed of 240 rpm to obtain a uniformly mixed activated precursor powder. This process not only achieves uniform mixing of materials but also significantly enhances the powder's reactivity through mechanochemical effects, inducing lattice defects and laying the foundation for the subsequent efficient aluminothermic reduction reaction.

[0048] S2. The activated precursor powder is pressed into a dense cylindrical blank (5cm in diameter, 1cm in height) and placed in a self-propagating high-temperature reaction apparatus. Under the protection of an argon atmosphere, a self-propagating high-temperature synthesis reaction dominated by aluminothermic reduction is triggered by local tungsten filament heating and ignition. The reaction first involves a violent reduction reaction of aluminum powder on rutile (TiO2), releasing a large amount of heat, which then drives the synthesis reaction between nascent titanium, molten aluminum, and carbon. The synthesis of the Ti2AlC MAX phase is completed within seconds. The entire SHS process uses the aluminothermic reduction reaction as the driving force and heat source, realizing the one-step completion of reduction and synthesis. The instantaneous ultra-high temperature environment of the SHS process can cause low-boiling-point impurities associated with the minerals (such as some components in SiO2 and Fe2O3) to volatilize and escape, or form a slag phase that can be separated from the main product, thereby achieving in-situ purification of impurities. This is a unique advantage that cannot be achieved by traditional slow heating sintering processes.

[0049] S3. The bulk material obtained from the reaction is coarsely crushed and then placed in a planetary ball mill and ground for 2 hours at a ball-to-material ratio of 5:1 and a rotation speed of 400 rpm. The ground powder is then passed through a 400-mesh sieve to obtain Ti2AlC MAX phase powder material.

[0050] The Ti2AlC MAX phase material was characterized by X-ray diffraction and scanning electron microscopy. Figure 1 The image shows the XRD pattern of the Ti2AlC MAX phase material prepared in this embodiment. Figure 1 It can be seen that the sample has obvious characteristic diffraction peaks at positions such as approximately 13.008° and 39.545°, which correspond to the (002) and (103) crystal planes of the Ti2AlC standard card (PDF#29-0095), respectively, indicating that the Ti2AlC phase was successfully synthesized. Figure 2 The image shows a SEM image of the Ti2AlC MAX phase material prepared in this embodiment. Figure 2 It can be seen that the obtained powder exhibits a typical MAX phase layered stacking morphology.

[0051] Example 2:

[0052] This embodiment provides a one-step method for preparing Ti3AlC2MAX phase materials using natural rutile as the titanium source and through aluminothermic reduction reaction coupled with self-propagating high-temperature synthesis technology. The specific preparation steps are as follows:

[0053] S1. First, precise calculations were performed based on the stoichiometric ratio of the target product Ti3AlC2 (Ti:Al:C=3:1:2) and the chemical equation for the aluminothermic reduction reaction (3TiO2+4Al→3Ti+2Al2O3) (taking the preparation of 20g of Ti3AlC2 material as an example). Natural rutile powder (TiO2 content ≥90wt%, 100 mesh), aluminum powder (purity 99.5%, 300 mesh), and graphite powder (purity 99.9%, 300 mesh) were weighed and mixed according to a molar ratio of Ti:Al:C=3:5.5:2. The above raw materials were placed in a planetary ball mill jar and ball-milled for 6 hours under high-purity argon protection at a ball-to-material mass ratio of 4:1 and a rotation speed of 240 rpm to obtain a uniformly mixed activated precursor powder.

[0054] S2. The activated precursor powder was pressed into a dense cylindrical preform (5 cm in diameter and 1 cm in height) and placed in a self-propagating high-temperature reaction apparatus. Under the protection of an argon atmosphere, a self-propagating high-temperature synthesis reaction dominated by aluminothermic reduction was triggered by local tungsten filament heating. The synthesis of the Ti3AlC2 MAX phase was completed within seconds. The entire SHS process was driven and heated by the aluminothermic reduction reaction, achieving a one-step completion of reduction and synthesis.

[0055] S3. The bulk material obtained from the reaction is coarsely crushed and then placed in a planetary ball mill and ground for 2 hours at a ball-to-material ratio of 5:1 and a rotation speed of 400 rpm. The ground powder is then passed through a 400-mesh sieve to obtain Ti3AlC2 MAX phase powder material.

[0056] The Ti3AlC2 MAX phase material was characterized by X-ray diffraction and scanning electron microscopy. Figure 3 The image shows the XRD pattern of the Ti3AlC2 MAX phase material prepared in this embodiment. Figure 3 It can be seen that the sample has obvious characteristic diffraction peaks at positions such as approximately 34.673° and 39.545°, which correspond to the (101) and (103) crystal planes of the Ti3AlC2 standard card (PDF#52-0875), respectively, indicating that the Ti3AlC2 phase was successfully synthesized. Figure 4 The image shows a SEM image of the Ti3AlC2 MAX phase material prepared in this embodiment. Figure 4 It can be seen that the obtained powder exhibits a typical MAX phase layered stacking morphology.

[0057] Example 3:

[0058] This embodiment provides a one-step method for preparing Cr2AlC MAX phase materials using natural chromite as the chromium source and through aluminothermic reduction reaction coupled with self-propagating high-temperature synthesis technology. The specific preparation steps are as follows:

[0059] S1. First, precise calculations are performed based on the stoichiometric ratio of the target product Cr2AlC (Cr:Al:C=2:1:1) and the chemical equation for the aluminothermic reduction reaction (Cr2O3+2Al→2Cr+Al2O3) (taking the preparation of 15g of Cr2AlC material as an example). Natural chromite powder (Cr2O3 content ≥40wt%, 100 mesh), aluminum powder (purity 99.5%, 300 mesh), and graphite powder (purity 99.9%, 300 mesh) are weighed and mixed according to a molar ratio of Cr:Al:C=2:3.5:1. The above raw materials are placed in a planetary ball mill jar and ball-milled for 6 hours under high-purity argon protection at a ball-to-material mass ratio of 4:1 and a rotation speed of 240 rpm to obtain a uniformly mixed activated precursor powder.

[0060] S2. The activated precursor powder is pressed into a dense cylindrical blank (5 cm in diameter and 1.5 cm in height) and placed in a self-propagating high-temperature reaction apparatus. Under the protection of an argon atmosphere, a self-propagating high-temperature synthesis reaction dominated by aluminothermic reduction is triggered by local tungsten filament heating and ignition. The reaction first involves a violent reduction reaction of aluminum powder on chromite powder (Cr2O3), releasing a large amount of heat, which then drives the synthesis reaction between nascent chromium, molten aluminum, and carbon. The synthesis of the Cr2AlC MAX phase is completed within seconds. The entire SHS process uses the aluminothermic reduction reaction as the driving force and heat source, realizing the one-step completion of reduction and synthesis.

[0061] S3. The bulk material obtained from the reaction is coarsely crushed and then placed in a planetary ball mill and ground for 2 hours at a ball-to-material ratio of 5:1 and a rotation speed of 400 rpm. The ground powder is then passed through a 400-mesh sieve to obtain Cr2AlC MAX phase powder material.

[0062] The Cr2AlC MAX phase material was characterized by X-ray diffraction and scanning electron microscopy. Figure 5 The image shows the XRD pattern of the Cr2AlC MAX phase material prepared in this embodiment. Figure 5 It can be seen that its diffraction peaks are similar to the standard spectrum of Cr2AlC. Figure One The target phase was successfully synthesized. Figure 6 The image shows a SEM image of the Cr2AlC MAX phase material prepared in this embodiment. Figure 6 It can be seen that it has obvious layered structure characteristics, proving that the method of the present invention is also applicable to the chromite system and can effectively prepare Cr-based MAX phase materials.

[0063] Example 4:

[0064] This embodiment provides a one-step method for preparing (Ti) titanium using natural rutile as the titanium source and natural chromite as the chromium source, through an aluminothermic reduction reaction coupled with a self-propagating high-temperature synthesis technique. 1 / 2 Cr1 / 2 The specific preparation steps for 2AlC bimetallic MAX phase materials are as follows:

[0065] S1. First, based on the target product (Ti) 1 / 2 Cr 1 / 2 The stoichiometric ratio of 2AlC and the aluminothermic reduction reaction were precisely calculated. Natural rutile powder (TiO2 content ≥ 90wt%, 100 mesh), natural chromite powder (Cr2O3 content ≥ 40wt%, 200 mesh), aluminum powder (purity 99.5%, 300 mesh), and graphite powder (purity 99.9%, 300 mesh) were weighed and mixed according to a molar ratio of Ti:Cr:Al:C = 1:1:4:1. The above raw materials were placed in a planetary ball mill jar and ball-milled for 6 hours under high-purity argon protection at a ball-to-material mass ratio of 4:1 and a rotation speed of 240 rpm to obtain a uniformly mixed activated precursor powder.

[0066] S2. The activated precursor powder is pressed into a dense cylindrical blank (5 cm in diameter, 1.4 cm in height) and placed in a self-propagating high-temperature reaction apparatus. Under an argon atmosphere, a self-propagating high-temperature synthesis reaction dominated by aluminothermic reduction is triggered by local tungsten filament heating and ignition. This reaction first involves a vigorous reduction reaction of aluminum powder on rutile (TiO2) and chromite powder (Cr2O3), releasing a large amount of heat, which then drives the synthesis reaction between nascent titanium and chromium, and molten aluminum and carbon. The synthesis is completed within seconds. 1 / 2 Cr 1 / 2 The synthesis of the 2AlC bimetallic MAX phase was achieved by using the aluminothermic reduction reaction as the driving force and heat source in the entire SHS process, realizing the one-step completion of reduction and synthesis.

[0067] S3. The bulk material obtained from the reaction is coarsely crushed, then placed in a planetary ball mill and ground for 2 hours at a ball-to-material ratio of 5:1 and a rotation speed of 400 rpm. The ground powder is then passed through a 400-mesh sieve to obtain (Ti). 1 / 2 Cr 1 / 2 )2AlC bimetallic MAX phase powder material.

[0068] The (Ti) prepared in this embodiment 1 / 2 Cr 1 / 2 XRD analysis of Ti2AlC powder showed a systematic shift in diffraction peak positions compared to single Ti2AlC or Cr2AlC, indicating successful solid solution of Ti and Cr atoms to form a single-phase bimetallic MAX phase solid solution. SEM images revealed a distinct layered structure. This embodiment demonstrates that the method described in this invention is not only applicable to the preparation of MAX phases of single metals, but can also be used to synthesize more complex bimetallic and even multimetallic MAX phase materials with tunable properties, further expanding the material system based on inexpensive minerals.

[0069] Example 5:

[0070] This embodiment provides an application of the Ti3AlC2 MAX phase material prepared in Example 2. Specifically, Ti3C2 MXene material is prepared using Ti3AlC2 MAX phase material as raw material, including the following steps:

[0071] S1. Take 2.0g of Ti3AlC2 MAX phase powder material and slowly add it to 40mL of pre-prepared etching solution. The etching solution is composed of 30mL of 12M hydrochloric acid (HCl), 10mL of deionized water and 3.2g of lithium fluoride (LiF).

[0072] S2. Place the mixture in a 35°C constant temperature water bath and continuously stir magnetically for 24 hours to carry out in-situ etching. During this process, LiF reacts with HCl to slowly generate HF, which then selectively etches away the Al atomic layers between the Ti3AlC2 layers.

[0073] S3. After the etching reaction is complete, the resulting mixture is washed repeatedly with deionized water by centrifugation (8000 rpm, 10 minutes each time) until the pH of the supernatant rises to above 6 to remove excess acid and dissolved ions.

[0074] S4. Add 50 mL of deionized water to the washed precipitate and perform ultrasonic exfoliation under argon protection (ultrasonic power 300 W, time 1 hour). Then centrifuge the dispersion (3500 rpm, 10 minutes) and collect the colloidal suspension containing a few layers of MXene. Finally, vacuum dry at 60 °C for 24 hours to obtain a few-layer Ti3C2 MXene powder.

[0075] Ti3C2 MXene material was characterized by X-ray diffraction and scanning electron microscopy. Figure 7 The image shows the XRD pattern of the Ti3C2 MXene material prepared in this embodiment. Figure 7 It can be seen that, compared with the precursor Ti3AlC2, its (002) diffraction peak has shifted significantly to a lower angle, indicating that the interlayer spacing has increased significantly due to the removal of the Al layer. Figure 8 The image shows a SEM image of the Ti3C2 MXene material prepared in this embodiment. Figure 8 As can be seen, the material exhibits a typical two-dimensional nanosheet stacked morphology, and the MXene accordion-like structure is clearly visible.

[0076] Comparative example:

[0077] This comparative example uses natural rutile as raw material and prepares Ti3AlC2 using a traditional high-temperature sintering process (non-SHS). The specific preparation steps are as follows:

[0078] The raw material ratio and ball milling activation conditions are the same as in Example 2. The difference is that in step S2, the activated powder is pressed into a blank, placed in a tube furnace, heated to 1350°C at a heating rate of 5°C / min under argon protection, held for 2 hours, and then cooled naturally. The post-processing steps are the same as in Example 2 to obtain Ti3AlC2.

[0079] The obtained product was analyzed by XRD. Figure 9 The XRD pattern of Ti3AlC2 prepared by traditional high-temperature sintering process is shown in the figure. Figure 9 It can be seen that the Ti3AlC2 phase content in the product is low, and a large amount of unreacted TiO2, Al2O3, and TiC impurities are present. This is because the traditional sintering process involves slow heating, making it difficult to precisely control the timing and temperature range of the aluminothermic reduction reaction, resulting in asynchronous reduction and synthesis and the generation of a large number of byproducts. Simultaneously, slow heating cannot produce the instantaneous ultra-high temperature of SHS, preventing impurities in the minerals from volatilizing or forming separable slag phases, leaving them largely residual in the product. This comparative result fully demonstrates the necessity of the SHS process of this invention: only the instantaneous high temperature of SHS can achieve the coupling of aluminothermic reduction and synthesis, and simultaneously complete the in-situ removal of impurities.

[0080] This invention provides a method for preparing MAX phase materials based on natural metal minerals. Many methods and approaches exist for implementing this technical solution; the above description is merely a preferred embodiment. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention. All components not explicitly stated in this embodiment can be implemented using existing technologies.

Claims

1. A method for preparing MAX phase materials based on natural metal minerals, characterized in that, Includes the following steps: S1. Natural metal mineral powder, aluminum powder and graphite powder are mixed and ball-milled to obtain activated precursor powder; S2. The activated precursor powder is pressed into a dense preform and placed in a self-propagating high-temperature reaction device. Under an inert protective atmosphere, the synthesis reaction is triggered by local tungsten wire heating and ignition to obtain bulk material. S3. After crushing the bulk material, sieve it to obtain the MAX phase powder material; The natural metallic mineral is rutile and / or chromite; the MAX phase powder material has the general formula (Ti 1- x Cr x ) n+1 AlC n , where 0≤x≤1, and n is 1 or 2.

2. The method according to claim 1, characterized in that, In S1, the ball milling process conditions are: time of 4 to 12 hours, ball-to-material ratio of (4 to 5):1, and rotation speed of 200 to 400 rpm.

3. The method according to claim 1, characterized in that, In S2, the blank is cylindrical in shape and has a diameter of 5cm.

4. The method according to claim 1, characterized in that, In S3, the crushing process conditions are as follows: time is 2 hours, ball-to-material ratio is (4~5):1, and rotation speed is 400 rpm.

5. The method according to any one of claims 1 to 4, characterized in that, The MAX phase powder material includes Ti2AlC, Ti3AlC2, Cr2AlC and (Ti 1 / 2 Cr 1 / 2 Any one of )2AlC.

6. The method according to claim 5, characterized in that, When the MAX phase powder material is Ti2AlC or Ti3AlC2, in S1, the molar ratio of each element in the activated precursor powder is Ti:Al:C = (2~3):(3.5~5.5):(1~2).

7. The method according to claim 5, characterized in that, When the MAX phase powder material is Cr2AlC, in S1, the molar ratio of each element in the activated precursor powder is Cr:Al:C = 2:(2.5~3.5):

1.

8. The method according to claim 5, characterized in that, When the MAX phase powder material is (Ti) 1 / 2 Cr 1 / 2 In S1, when 2AlC is used, the molar ratio of each element in the activated precursor powder is Ti:Cr:Al:C = 1:1:(2.5~4):

1.

9. The MAX phase material prepared by the method according to any one of claims 1 to 8.

10. The application of the MAX phase material according to claim 9 in the preparation of MXene materials.

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