Porous high-entropy alloy filter body carrier as well as preparation method and application thereof

Abstract

The invention discloses a porous high-entropy alloy filter body carrier and a preparation method and application thereof. The porous high-entropy alloy filter body carrier is composed of four elements of aluminum, iron, chromium and nickel. By controlling the aluminum content and a calcining process, the carrier does not generate macroscopic cracks after being subjected to 50 times of rapid cooling and thermal shock cycles from 900 DEG C to room temperature; the oxidation weight gain rate after 40 hours of oxidation in static air at 900 DEG C is lower than 14%; after thermal shock circulation, the microstructure is a body-centered cubic BCC and face-centered cubic FCC double-phase mixed structure. The invention successfully solves the bottleneck problems of the traditional carrier material in the aspects of high temperature, thermal shock, oxidation resistance and the like, and provides a novel filter carrier material which is high in performance, low in cost and easy to industrialize for an automobile exhaust purification system.

Description

Technical Field

[0001] This invention relates to a carrier material for purifying automotive exhaust gases, and more particularly to a porous high-entropy alloy filter carrier and its preparation method. It belongs to the field of materials synthesis and processing. Background Technology

[0002] Currently, commonly used carrier materials for diesel engine particulate filters and catalytic converters mainly include cordierite, silicon carbide (SiC) ceramics, and heat-resistant alloys. However, these materials, limited by their intrinsic properties, all have significant shortcomings when dealing with increasingly harsh high-temperature, vibration, and thermal shock conditions: cordierite has a low melting point and poor thermal conductivity, which is not conducive to rapid ignition and uniform temperature distribution in the filter, and is prone to local overheating; its intrinsic brittleness and low thermal shock resistance also make it prone to cracking and failure under drastic temperature changes. Although silicon carbide has excellent high-temperature performance, its high coefficient of thermal expansion and insufficient thermal shock resistance pose a severe challenge to the overall design and encapsulation technology of the carrier to offset thermal stress and prevent cracking, increasing manufacturing costs and complexity. Heat-resistant alloys are limited by their insufficient high-temperature oxidation resistance, and their long-term operating temperature is usually below 1200℃. Furthermore, the oxide layer that continuously forms at high temperatures can lead to carrier performance degradation and may affect catalyst adhesion and activity.

[0003] To overcome the performance bottlenecks of traditional materials, many researchers have turned their attention to intermetallic compounds that combine the advantages of metals and ceramics. Compared with traditional binary / ternary intermetallic compounds, new high-entropy intermetallic compounds have superior room temperature strength, plasticity, and high temperature oxidation resistance, and are expected to become ideal high-temperature filter carrier materials.

[0004] However, successfully applying high-entropy alloys to porous filter carriers faces a series of challenges, which greatly hinder their transition from laboratory to engineering applications: First, high-entropy alloys have diverse components, with significant differences in reaction initiation temperatures, exothermic behaviors, and diffusion rates among elements. This easily leads to incomplete reactions and component segregation. During conventional sintering, these differences can easily cause severe elemental segregation, preventing the formation of a homogeneous single solid solution phase and instead generating brittle intermetallic compounds, completely negating the core advantages of high-entropy alloys and affecting the carrier's lifespan. Second, porous carriers require a stable and interconnected three-dimensional pore structure, but the inherent "hysteresis diffusion effect" of high-entropy alloys makes atomic migration difficult. Densification sintering is already very challenging; after introducing pore-forming agents, how to ensure high porosity while achieving a strong metallurgical bond between powder particles to obtain sufficient strength is a dilemma. Third, in high-entropy alloy systems, Al is a key component, and its content can be controlled to regulate the phase structure. An appropriate amount of Al helps form the FCC phase, improving the toughness and plasticity of the material; however, when it exceeds a certain threshold, it promotes the formation of an ordered B2 structure (belonging to the BCC class), giving the alloy higher strength and oxidation resistance. Therefore, in the design and sintering process, how to accurately control the Al content to regulate the phase composition is crucial to the overall performance of the material.

[0005] Currently, publicly available technologies, such as those described in Volume 33 (2024) of the *Journal of Materials Research and Technology* (pp. 3324–3333), utilize reaction sintering to prepare porous FeCoNiMnCr high-entropy alloys, exhibiting excellent oxidation resistance at 900℃. However, these alloy powders contain a large amount of Co, which is expensive and unsustainable. Furthermore, the sintered material system contains only a single FCC phase, exhibiting good plasticity and toughness but relatively low strength. These technologies fail to address the critical issues of thermal shock resistance and high strength in the practical application of high-temperature filter carrier materials. While suitable for basic research, they are not feasible for industrialization. Chinese patent application number 201610088222.2 discloses a porous high-entropy alloy and its preparation method. This method successfully prepares a porous structure by mixing high-entropy alloy powder with a pore-forming agent according to the target porosity and pore size requirements, and then employing spark plasma sintering technology. However, spark plasma sintering equipment is expensive and cannot meet the needs of large-scale industrialization. Research on the preparation of porous high-entropy alloys using traditional powder metallurgy is still relatively limited.

[0006] Therefore, there is an urgent need to develop a high-performance porous high-entropy alloy carrier and its preparation method that can overcome the difficulties of high-entropy alloy sintering and is suitable for engineering preparation. Summary of the Invention

[0007] To overcome the above-mentioned defects of the prior art, the present invention provides a porous high-entropy alloy filter carrier and its preparation method. As a novel carrier material, this porous high-entropy alloy filter carrier achieves multiple advantages, including low cost, good mechanical properties, high-temperature oxidation resistance, and high-temperature thermal shock resistance, by controlling the aluminum content and calcination process.

[0008] A porous high-entropy alloy filter carrier, characterized in that it is composed of four elements: aluminum (Al), iron (Fe), chromium (Cr), and nickel (Ni); and by controlling the aluminum content and calcination process, the carrier meets the following conditions: No macroscopic cracks were generated after 50 cycles of rapid cooling and thermal shock from 900°C to room temperature; The mass change rate after oxidation in static air at 900℃ for 40 hours was less than 14%. After thermal shock cycling, its microstructure is a hybrid structure of body-centered cubic (BCC) and face-centered cubic (FCC) phases.

[0009] Furthermore, the BCC and FCC biphase hybrid structure is inherent to the carrier, and it consists of a BCC solid solution phase and an FCC solid solution phase both before and after thermal shock cycling.

[0010] Furthermore, before undergoing thermal shock cycling, the carrier's microstructure is a single-phase BCC solid solution structure; after thermal shock cycling, the resulting two-phase mixed structure consists of a BCC solid solution matrix and FCC precipitates dispersed within it; at this point, the carrier's strength increases rather than decreases after thermal shock.

[0011] Furthermore, the molar ratio of Al, Fe, Cr, and Ni is Al : Fe : Cr : Ni = x : 1 : 1 : 1, and 0.3 ≤ x ≤ 1.0. A further selection is (0.5-0.7): 1 : 1 : 1. Preferably, it is 0.7: 1 : 1 : 1.

[0012] Furthermore, the porous high-entropy alloy filter carrier also includes three-dimensional interconnected channels formed by a pore-forming agent, wherein the pore-forming agent is polymethyl methacrylate (PMMA).

[0013] The preparation method of the above-mentioned porous high-entropy alloy filter carrier includes the following steps: Step 1: Weigh out Al powder, Fe powder, Cr powder, and Ni powder, and mix them according to the predetermined molar ratio; Step 2: The mixed powder is subjected to reaction sintering. The reaction sintering adopts a gradient heating process: first, the temperature is increased from room temperature to 580℃±20℃ at 1-3℃ / min and held for 0.5-2h; then, the temperature is increased to 900℃±50℃ at 1-3℃ / min and held for 0.5-2h; finally, the temperature is increased to 1250℃~1350℃ at 3-7℃ / min and held for 2-4h.

[0014] Furthermore, in the powder mixing step, 4%-8% of polymethyl methacrylate (PMMA) is added as a pore-forming agent. The gradient heating process described here is as follows: the temperature is increased from room temperature to 200℃ at 2℃ / min, then increased to 400℃ at 1℃ / min and held for 2 hours to remove PMMA, then increased to 580℃±20℃ at 1-3℃ / min and held for 0.5-2 hours, then increased to 900℃±50℃ at 1-3℃ / min and held for 0.5-2 hours, and finally increased to 1250℃~1350℃ at 3-7℃ / min and held for 2-4 hours.

[0015] The application of the porous high-entropy alloy carrier of the present invention in the particulate filter for automobile exhaust purification.

[0016] The beneficial effects of this invention are as follows: 1. Low material cost, wide availability, and strong economic applicability. This invention uses four common metals—Al, Fe, Cr, and Ni—as the main raw materials. The powders are abundant, and the invention has good economic efficiency and applicability in practical applications. The powders are relatively inexpensive, and the use of metals such as Co is avoided, which reduces material costs and improves supply chain stability, thus showing good prospects for industrialization.

[0017] 2. Excellent high-temperature oxidation resistance and corrosion resistance This invention utilizes the synergistic effect of Al and Cr elements to form a dense oxide film (Cr2O3 / Al2O3) on the material surface, thereby improving its corrosion resistance in acidic environments and its oxidation resistance at high temperatures. In addition, Ni-containing materials have certain catalytic properties and gas adsorption properties.

[0018] 3. Excellent thermal shock resistance In the rapid cooling and thermal shock cycle test from 900℃ to room temperature, the present invention does not produce cracks after 50 cycles. After thermal shock, some of the strength not only does not decrease but also increases, which meets the requirements of thermal shock stability of the automotive exhaust purification system under normal conditions.

[0019] 4. Balancing high strength and structural stability This invention, through rational composition design and gradient sintering process, enables the prepared support to maintain its microstructure after thermal shock cycling. The structure is a hybrid two-phase structure of body-centered cubic (BCC) and face-centered cubic (FCC), with the two phases working synergistically in terms of oxidation resistance and thermal shock resistance. For oxidation resistance, the BCC phase, acting as a "reservoir" of Al / Cr elements, preferentially forms an oxide film. The FCC phase provides matrix toughness and support, protected by the oxide film. For thermal shock resistance, the BCC phase provides strength, while the FCC phase absorbs energy through plastic deformation, deflecting and passivating cracks together with the interface. When the aluminum content is 0.7%, the compressive strength after cyclic oxidation increases to 239.6 MPa due to the formation of the two-phase structure, and it also exhibits a low coefficient of thermal expansion, combining good mechanical properties with high-temperature structural stability.

[0020] 5. Controllable three-dimensional interconnected pore structure optimizes filtration performance. This invention introduces PMMA as a pore-forming agent and combines it with a gradient heating process to achieve a three-dimensional interconnected pore structure with adjustable porosity. This structure facilitates gas flow, reduces pressure drop, alleviates filtration resistance, and improves filtration efficiency, making it suitable for the application requirements of high-performance particulate filters.

[0021] 6. The preparation process is simple and suitable for industrial-scale promotion. This invention employs a reaction sintering combined with a gradient heating process for raw materials containing pore-forming agents. First, the temperature is held at 400°C for 2 hours to fully remove PMMA. Then, the temperature is slowly increased to 580°C and held thereafter. This temperature is below the melting point of Al, utilizing solid-state diffusion to buffer the subsequent high-temperature reaction stages. The temperature is then increased to 900°C, which accelerates the solid-state diffusion process, preparing for "pre-alloying." The temperature is further increased to 1300°C by increasing the heating rate. Rapid heating reduces the total time at high temperatures, inhibiting excessive grain growth. Furthermore, elements such as Fe, Cr, and Ni have significant differences in atomic size, resulting in high mixing entropy but slow diffusion (a hysteresis diffusion effect). The high temperature of 1300°C provides the necessary conditions to overcome interatomic energy barriers and promote sufficient interdiffusion of elements, which is one of the keys to forming a homogeneous BCC and FCC solid solution dual-phase system. This method avoids expensive spark plasma sintering equipment, offers controllable and reproducible process conditions, and is suitable for large-scale engineering preparation, demonstrating significant potential for widespread application.

[0022] In summary, this invention is innovative in terms of composition design, structural control and preparation process of porous high-entropy alloy carrier materials. It successfully solves the bottleneck problems of traditional carrier materials in terms of high temperature, thermal shock and oxidation resistance, and provides a new type of filter carrier material with high performance, low cost and easy industrialization for automotive exhaust purification systems. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 For the porous materials x(Al) with different Al contents of the present invention x Porosity and compressive strength diagram of FeCrNi.

[0025] Figure 2 The images show the XRD patterns of porous materials with different Al contents according to the present invention.

[0026] Figure 3 This is a comparison chart of the porosity and compressive strength of porous materials with and without pore-forming agent (with 5% PMMA pore-forming agent) in Example 2 of the present invention.

[0027] Figure 4 This is a comparison chart of the porosity and compressive strength of the porous materials prepared in Examples 3 and 6 of the present invention.

[0028] Figure 5 This is a SEM image of the porous material prepared in Example 6 of the present invention.

[0029] Figure 6 The residual compressive strength of porous materials with different Al contents of the present invention after 50 cycles at 900°C.

[0030] Figure 7 This is a graph showing the oxidation weight gain rate of porous materials with different Al contents of the present invention after being kept at 900°C for 40 hours.

[0031] Figure 8 This is a graph showing the thermal shock resistance of porous materials with different Al contents at 1100℃ according to the present invention.

[0032] Figure 9 This is a graph showing the oxidation weight gain rate of porous materials with different Al contents of the present invention after being kept at 1100℃ for 100 hours.

[0033] Figure 10 This is a graph showing the coefficient of thermal expansion of porous materials with different Al contents in the range of room temperature to 1000°C.

[0034] Figure 11 The XRD patterns of porous materials with different Al contents of the present invention after 50 thermal shock cycles at 900℃ are shown. Detailed Implementation

[0035] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and several embodiments, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more explicit definition of the scope of protection of the present invention.

[0036] Example 1: Taking the preparation of a carrier with a biphase structure before and after thermal shock cycling as an example Step 1: Preparation of raw materials Fe powder, Al powder, Ni powder, and Cr powder are used as raw materials; the molar ratio of raw materials Al, Fe, Cr, and Ni is 0.3:1:1:1. The particle size of the Al powder is about 20 μm, the particle size of the Fe powder is about 20 μm, the particle size of the Cr powder is about 40 μm, and the particle size of the Ni powder is about 20 μm.

[0037] Step 2: Powder Mixing Weigh the powder accurately according to the proportions, and mix the metal powder in a ball mill for 30 minutes to ensure thorough mixing.

[0038] Step 3: Reaction Sintering The dried sample was heated from room temperature to 580℃ at a rate of 2℃ / min and held for 1 hour, then heated to 900℃ at a rate of 2℃ / min and held for 1 hour, and finally heated to the sintering temperature of 1300℃ at a rate of 5℃ / min and held for 3 hours. The prepared porous material had a porosity of 38.8% and a compressive strength of 866.4 MPa. (See attached figure) Figure 1 As shown.

[0039] Example 2: Taking the preparation of a carrier with a biphase structure before and after thermal shock cycling as an example Except for changing the content of Al powder added in the first step of porous material powder mixing preparation from 0.3 mol to 0.5 mol, all other processes and parameters are the same as in Example 1. The prepared porous material has a porosity of 39.3% and a compressive strength of 660.0 MPa (see attached figure). Figure 1 As shown.

[0040] Example 3: Taking the preparation of a carrier that has a single-phase BCC solid solution structure before thermal shock cycling and a two-phase structure after thermal shock cycling as an example. Except for changing the Al powder content in the first step of porous material powder mixing preparation from 0.3 mol to 0.7 mol, all other processes and parameters are the same as in Example 1. The prepared porous material has a porosity of 40.8% and a compressive strength of 177.8 MPa (see Appendix). Figure 1 As shown.

[0041] Example 4: Taking the preparation of a carrier that has a single-phase BCC solid solution structure before thermal shock cycling and a two-phase structure after thermal shock cycling as an example. Except for changing the content of Al powder added in the first step of porous material powder mixing preparation from 0.3 mol to 1.0 mol, all other processes and parameters are the same as in Example 1. The prepared porous material has a porosity of 46.5% and a compressive strength of 95.1 MPa (see attached figure). Figure 1 As shown.

[0042] Example 5: Adding pore-forming agent PMMA to the first step of the porous material powder mixing preparation in Example 2. In Example 5, PMMA, a pore-forming agent, was added. The PMMA particle size was approximately 20 μm, and the mass fraction was 5% (meaning 5% of the total mass of the high-entropy alloy mixed powder). The molar ratio of Al, Fe, Cr, and Ni was 0.5:1:1:1. The third step of the reaction sintering process involved heating the dried sample from room temperature to 200°C at a rate of 2°C / min, then heating it to 400°C at a rate of 1°C / min and holding it for 2 hours to remove PMMA. Subsequent processes and parameters were the same as in Example 1. The prepared porous material had a porosity of 50.6% and a compressive strength of 179.2 MPa (see Example 1). Figure 3 ).

[0043] Example 6: Adding pore-forming agent PMMA to the first step of the porous material powder mixing preparation in Example 3. Example 6: PMMA, a pore-forming agent, was added. The PMMA particle size was approximately 20 μm, and the mass fraction was 5% (referring to 5% of the total mass of the powder mixed with the high-entropy alloy). The molar ratio of Al, Fe, Cr, and Ni was 0.7:1:1:1. The third step, reaction sintering, involved heating the dried sample from room temperature to 200°C at a rate of 2°C / min, then heating it to 400°C at a rate of 1°C / min and holding it for 2 hours to remove the PMMA. Subsequent processes and parameters were the same as in Example 1. The prepared porous material had a porosity of 52.0% and a compressive strength of 63.5 MPa (see Example 1). Figure 4 ).

[0044] Figure 3 and Figure 4 The figures show a comparison of porosity and compressive strength of the materials with and without pore-forming agents, respectively, when the Al powder content is 0.5 and 0.7 mol, and with and without 5% PMMA pore-forming agent. Figure 3 As can be seen, under the same conditions, the addition of a pore-forming agent to the material in Example 2 increased the porosity from 39.3% to 50.6%, an increase of 28.75%, but simultaneously reduced the compressive strength from 660.0 MPa to 179.2 MPa, a decrease of 72.85%. Figure 4It can be seen that the addition of a pore-forming agent to the material in Example 3 increased the porosity from 40.8% to 52.0%, an increase of 27.45%. However, the compressive strength decreased from 177.8 MPa to 63.5 MPa, a decrease of 64.29%. This indicates that the pore-forming agent has a significant impact on the mechanical strength of the carrier. In practical applications, the amount of pore-forming agent added must be strictly controlled to balance the contradiction between compressive strength and porosity.

[0045] To further verify the phase composition and thermal shock resistance of the porous materials of the present invention, the phase composition of the porous material samples prepared in Examples 1 to 4 of the present invention without the addition of pore-forming agents was analyzed before and after thermal shock resistance. The analysis results are shown in [the table below]. Figure 2 and Figure 11 The porous material samples prepared in Examples 1 to 4 were kept at 900°C for 1 hour and then cooled in air for 30 minutes. This process constituted one thermal shock cycle. This thermal shock cycle was repeated 50 times. No cracks appeared, and the residual compressive strength was tested. The test results are as follows: Figure 6 As shown. Simultaneously, the samples from Examples 1 to 4 were oxidized at 900℃ for different times (1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, 15h, 20h, 30h, 40h), and the weight gain from oxidation was calculated. The calculation results are shown in [Figure number missing]. Figure 7 .

[0046] from Figure 2 As can be seen, when the Al content of the present invention is 0.3 and 0.5, the prepared samples (referred to as Al) 0.3 Porous materials and Al 0.5 The porous material exhibits a two-phase structure dominated by the FCC phase and a small amount of the BCC phase. When the Al content increases to 0.7% and 1%, the samples (referred to as Al) show different phases. 0.7 Porous materials and Al 1.0 Porous materials (containing only the BCC phase). From Figure 11 It can be seen that after 50 cycles of thermal shock at 900℃, Al 0.3 And Al 0.5 Porous materials still exhibit a two-phase structure dominated by the FCC phase and containing a small amount of the BCC phase, while Al... 0.7 And Al 1.0 The porous material consists of a BCC solid solution matrix and FCC precipitates dispersed within it. This demonstrates that precise control of the Al content can regulate the phase composition, which aligns with the original concept of this invention.

[0047] from Figure 6 As can be seen, after 50 thermal shock cycles, Al 0.3 And Al 0.5 The compressive strength of porous materials decreased by 48.95% and 8.71%, respectively. Al 0.7And Al 1.0 The compressive strength of the porous material increased by 34.76% and 62.04%, respectively. Given Al... 0.3 Porous materials suffer too much compressive strength loss after thermal shock, while Al 1.0 Although the compressive strength of porous materials increases significantly after thermal shock, their original compressive strength is too low. Therefore, it is more appropriate to control the molar ratio of Al, Fe, Cr and Ni in porous materials at Al:Fe:Cr:Ni = (0.5-0.7):1:1:1.

[0048] As the Al content increases, the rate of mass change should gradually decrease, mainly because the formed Al₂O₃ acts as an air barrier. However, simultaneously, the rate of mass change of the sample gradually increases with time, due to prolonged high temperatures. However, from... Figure 7 It can be seen that when the Al content is 0.5% and 0.7%, the high-temperature antioxidant properties of the samples are comparable, but combined with... Figure 6 It can be seen that after 50 thermal cycles at 900℃, the thermal shock resistance of Al... 0.5 Although the residual compressive strength of porous materials (602.5 MPa) is higher than that of Al, 0.7 The residual compressive strength of the porous material (239.6 MPa), but Al 0.7 The compressive strength of porous materials increases after cyclic oxidation. (Further details to be added...) Figure 3 and Figure 4 Chinese AI 0.5 And Al 0.7 The study investigated the decrease in strength and the increase in porosity of porous materials after the addition of pore-forming agents. It was found that, although Al... 0.5 Porous materials are more porous than Al 0.7 The porosity of the porous material increased by 1.3 percentage points, but its compressive strength decreased more than that of Al. 0.7 Porous materials accounted for 8.6 percentage points, which proves that Al 0.7 Porous materials have better overall performance than Al 0.5 Porous materials.

[0049] To further compare the comprehensive performance of the porous materials prepared in Examples 1 to 4 of this invention, the coefficients of thermal expansion of the porous material samples prepared in Examples 1 to 4 were tested in the range of room temperature to 1000°C. The test results are shown in [Figure 1]. Figure 10 .from Figure 10 It can be seen that Al 0.7 Porous materials and Al 1.0 The coefficient of thermal expansion of porous materials is significantly lower than that of Al. 0.3 Porous materials and Al 0.5 The coefficient of thermal expansion of porous materials, especially Al 0.7Porous materials have the lowest coefficient of thermal expansion, combined with Figure 6 Based on the results of compressive strength loss, Al showed the best thermal shock resistance. 0.7 Porous materials.

[0050] The microstructure of the porous material sample obtained in Example 6 was tested, and the test results are shown in [the table below]. Figure 5 ,from Figure 5 As can be seen, the pores are three-dimensionally interconnected. Adjusting the particle size and content of the pore-forming agent can modify the pore size, porosity, and maximum and minimum pore diameter of the porous material. This hierarchical pore structure is beneficial for increasing the porosity of the porous material, reducing pressure drop, and mitigating the increase in filtration resistance.

[0051] In addition, the samples prepared in Examples 1 to 4 were kept at 1100°C for 1 hour and then cooled in air to test their thermal shock resistance. Figure 8 As shown. From Figure 8 As can be seen from this, Al still has better thermal shock resistance. 0.5 And Al 0.7 The porous material sample only began to develop cracks after 12 cycles of testing. Additionally, the samples were oxidized at 1100℃ for different times (5h, 10h, 15h, 20h, 30h, 40h, 50h, 60h, 70h, 80h, 90h, 100h), and the weight gain from oxidation was calculated. Figure 9 As shown. From Figure 9 It can also be seen that Al 0.7 The mass change rate of porous materials after high-temperature oxidation is lower than that of Al. 0.5 Porous materials, mainly due to the fact that after long-term oxidation, Al 0.7 The oxide layer formed in porous materials is mainly composed of Al2O3, which is extremely stable at high temperatures, while Al... 0.5 The oxide layer formed by the porous material is mainly Cr2O3. Cr2O3 decomposes upon reaction with oxygen at 1100℃, leading to the failure of the protective film. Due to insufficient Al content, a continuous Al2O3 film cannot be formed, resulting in rapid and continuous oxidation and thus exhibiting a high weight gain rate. This indicates that under prolonged high-temperature conditions, Al... 0.7 Porous materials have better oxidation resistance than Al. 0.5 Porous materials.

[0052] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions conceived without inventive effort should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A porous high-entropy alloy filter carrier, characterized by, It is composed of four elements of aluminum, iron, chromium and nickel; and by controlling the aluminum content and calcination process, the carrier satisfies the following conditions: No macroscopic cracks are generated after 50 thermal shock cycles from 900℃ to room temperature; The mass change rate after oxidation in static air at 900℃ for 40 hours is less than 14%; After thermal shock cycles, its microstructure is a dual-phase mixed structure of body-centered cubic BCC and face-centered cubic FCC.

2. The porous high-entropy alloy filter carrier of claim 1, wherein, The BCC and FCC dual-phase mixed structure is inherent to the carrier, and is composed of BCC solid solution phase and FCC solid solution phase before and after thermal shock cycles.

3. The porous high-entropy alloy filter carrier of claim 1, wherein, Before thermal shock cycles, the carrier microstructure is a single-phase solid solution structure of BCC; and the dual-phase mixed structure formed after thermal shock cycles is composed of BCC solid solution matrix and FCC precipitated phase dispersedly distributed therein.

4. The porous high-entropy alloy filter carrier of claim 1, wherein, The molar ratio of Al, Fe, Cr and Ni is Al:Fe:Cr:Ni=x:1:1:1, and 0.3≤x≤1.

0.

5. The porous high-entropy alloy filter carrier of claim 4, wherein, The molar ratio of Al, Fe, Cr and Ni is Al:Fe:Cr:Ni=(0.5-0.7):1:1:

1.

6. The porous high-entropy alloy filter carrier of claim 5, wherein, The molar ratio of Al, Fe, Cr and Ni is Al:Fe:Cr:Ni=0.7:1:1:

10.

7. The porous high-entropy alloy filter carrier of claim 1, wherein, The porous high-entropy alloy filter carrier further comprises three-dimensional interconnected pores formed by a pore-forming agent, and the pore-forming agent is polymethyl methacrylate.

8. A method of producing a porous high-entropy alloy filter carrier according to any one of claims 1 to 7, characterized in that The method comprises the following steps: Step 1: weigh Al powder, Fe powder, Cr powder and Ni powder, and mix them according to the predetermined molar ratio; Step 2: reaction sintering of the mixed powder, the reaction sintering adopts a gradient heating process: first, from room temperature to 580℃±20℃ at 1-3℃ / min and keep for 0.5-2h, then to 900℃±50℃ at 1-3℃ / min and keep for 0.5-2h, finally to 1250℃~1350℃ at 3-7℃ / min and keep for 2-4h.

9. The method of claim 8, wherein the porous high-entropy alloy filter carrier is prepared by a process comprising: providing a porous high-entropy alloy substrate; and coating the porous high-entropy alloy substrate with a biocompatible material. In the mixed powder step, 4%-8% of polymethyl methacrylate as a pore-forming agent is also added to the total mass of the mixed powder; at this time, the gradient heating process is: from room temperature to 200℃ at 2℃ / min, to 400℃ at 1℃ / min and keep for 2h to remove PMMA, then to 580℃±20℃ at 1-3℃ / min and keep for 0.5-2h, to 900℃±50℃ at 1-3℃ / min and keep for 0.5-2h, finally to 1250℃~1350℃ at 3-7℃ / min and keep for 2-4h.

10. Application of the porous high-entropy alloy filter carrier according to any one of claims 1-5 in a vehicle exhaust purification particulate trap.

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