Porous metal ceramic composite material and preparation method thereof

Abstract

The invention belongs to the field of composite metal materials, and particularly relates to a porous metal ceramic composite material and a preparation method thereof. The method comprises the following steps: 1) preparing ceramic slurry by taking a metal fiber felt as a base material, and then coating the ceramic slurry on the surface of the metal fiber felt for surface drying to form a metal ceramic composite precursor; and 2) after the metal ceramic composite precursor is connected into an electrical system, electrifying to generate resistance heat for Joule heat treatment, and developing a novel porous metal ceramic composite material. According to the invention, through Joule heat induced instantaneous interface metallurgical reaction, strong combination of the ceramic coating and the metal matrix is creatively realized, the problem that the coating is easy to crack and peel off is solved, the long-term reliability of the material in a harsh environment is remarkably improved, and the material has good application prospects while high flux and low pressure drop are maintained. And meanwhile, the whole process is low in energy consumption, simple in equipment and short in flow, and has remarkable industrial production advantages.

Description

Technical Field

[0001] This invention belongs to the field of composite metal materials, and particularly relates to a porous metal-ceramic composite material and its preparation method. Background Technology

[0002] Porous metallic materials, due to their excellent mechanical strength, good thermal shock resistance, designable pore structure, and high permeability, have become the basic materials for key filtration components in chemical, metallurgical, energy, and environmental protection fields. However, when alloy materials are used for long-term service in harsh environments containing chloride ions, sulfides, or high-temperature oxidizing atmospheres, the passivation film on their surface is easily damaged, leading to pitting corrosion, crevice corrosion, and high-temperature oxidation. This not only causes corrosion failure of the filter element, but the formation and accumulation of corrosion products also alter the pore structure, causing filtration accuracy drift and increased pressure drop, severely limiting their application in harsh industrial environments.

[0003] Currently, industry professionals primarily select different alloys, polymers, or ceramics to manufacture filter media based on service conditions to meet specific requirements. However, development is currently largely based on a single material. Single-material polymer, ceramic, or metal filter media are increasingly unable to meet the requirements of particularly demanding operating conditions. For example, polymers are not resistant to high temperatures, metals have poor corrosion resistance and extreme temperature resistance, and ceramics lack sufficient thermal shock resistance and reliability. Therefore, in the filter media development process, breaking through the limitations of single materials and developing composite filter media is a crucial solution to overcoming the performance bottlenecks of single-material filter media. For instance, the combination of metals and ceramics can simultaneously address the issues of high brittleness in ceramics and poor high-temperature corrosion resistance in metals.

[0004] To improve the corrosion resistance of dense metallic materials, surface coating technologies such as thermal spraying, sol-gel methods, and high-temperature sintering have been applied in some high-temperature scenarios. However, these methods generally have the following limitations: such as weak interfacial adhesion; the significant difference in the coefficients of thermal expansion between ceramics and metals generates huge thermal stress during coating preparation and thermal cycling, leading to easy cracking, blistering, or even peeling off of the coating from the substrate. In particular, traditional coating processes are difficult to apply to the surface protection of porous metallic material skeletons, easily leading to overfilling or clogging of surface pores while the internal skeleton is difficult to penetrate and modify, hindering industrialization.

[0005] Therefore, there is an urgent need to develop a new type of composite material and preparation technology that can achieve a high-strength bond between ceramic coatings and porous metal skeletons, with a simple and efficient process, and can synergistically optimize corrosion resistance and filtration flux. Summary of the Invention

[0006] To address the problems of surface corrosion and grain boundary corrosion that easily occur in 316L porous stainless steel sintered felt under high temperature and strong corrosive environments, and the lack of effective surface protection measures, this invention proposes a porous metal-ceramic composite material and a method for preparing the composite material.

[0007] The main objective of this invention is: 1. While maintaining the strength of the porous metal skeleton and the three-dimensional interconnected pore structure, a continuous and dense basalt-based ceramic protective layer is constructed on the surface of 316L sintered felt to improve the material's corrosion resistance and high-temperature oxidation resistance in high-temperature, chlorine-containing or other corrosive media. Second, by controlling the thickness of the basalt coating and its filling depth in the surface pores, the effective pore size and filtration flux can be synergistically controlled, so that the composite material can maintain high flux and high filtration accuracy while obtaining high corrosion resistance. Third, by utilizing the Joule heating generated by the resistance of 316L sintered felt, rapid melting and cooling solidification of basalt powder can be achieved, thus constructing a new route for the preparation of porous metal-ceramic composite materials that is simple in equipment, low in energy consumption, short in processing cycle, and suitable for engineering scale-up.

[0008] To achieve the above objectives, the present invention adopts the following technical solution.

[0009] A method for preparing a porous metal-ceramic composite material. The method includes: 1) Using metal fiber felt as the substrate, ceramic slurry is prepared and then coated onto the surface of the metal fiber felt to form a metal-ceramic composite precursor. 2) After the metal-ceramic composite precursor is connected to the electrical system, it undergoes Joule heat treatment to generate resistance heat, thereby obtaining a porous metal-ceramic composite material.

[0010] As a preferred option Step 1) The metal fiber felt is stainless steel fiber felt; In the specific implementation of this invention, the main material is 316L stainless steel fiber felt, but in actual production and use, it should not be limited to only this one grade of stainless steel fiber felt; other alloy materials and porous materials developed by powder sintering, fiber weaving, fiber sintering and other methods can also adopt this method.

[0011] The stainless steel fiber felt is pretreated before use.

[0012] As a preferred option The pretreatment includes cleaning and activation; The activation solution used for activation is a 3-10 wt% hydrochloric acid aqueous solution, and the activation treatment time is 1-10 min; After activation, the product is dried at 50–70 °C for 1–3 h.

[0013] As a preferred option Step 1) The ceramic slurry is made of basalt powder, ground to D... 90 After reaching a particle size ≤5 μm, it is mixed with an organic solvent at a mass ratio of 1:(0.6~2.0) and stirred evenly to obtain the basalt powder. The basalt powder can be prepared in-house; the basalt powder used in the embodiments of this invention is all in-house prepared, mixed with aluminum silicate, iron silicate, and boron oxide at a mass ratio of 6:3:1, and then subjected to planetary ball milling to D. 90 ≤5 μm is acceptable.

[0014] As a preferred option Step 1) The coating process is performed by dip coating.

[0015] As a preferred option Step 2) The process of generating Joule heat by energizing is controlled with an energizing current of 70-90 A and an energizing duration of 5-30 s.

[0016] As a preferred option Step 2) The Joule heat treatment is performed in a protective atmosphere.

[0017] A porous metal-ceramic composite material.

[0018] The core of this invention lies in the innovative application of "Joule heating instantaneous metallurgical bonding" technology to the surface ceramic modification of porous metal skeletons. By utilizing the conductive metal substrate itself as a heat source, controllable local ultra-high temperatures are generated in an extremely short time, driving the pre-coated basalt powder to melt, diffuse and react at the interface, and then rapidly solidify, thereby achieving a high-strength bond between the ceramic coating and the metal skeleton, as well as the densification and gradient construction of the coating itself in one step. This technology cleverly bypasses the common industry problems of high energy consumption and substrate performance degradation caused by prolonged high-temperature treatment in traditional processes, as well as interface stress concentration and easy coating peeling due to thermal expansion coefficient mismatch.

[0019] Specifically, the present invention achieves its superior performance through the following four synergistic mechanisms.

[0020] Firstly, pretreatment is crucial. Cleaning and hydrochloric acid activation pretreatment of the 316L stainless steel fiber felt are essential. Cleaning ensures the cleanliness of the substrate surface and pores, creating conditions for uniform wetting and adhesion of the slurry. The short-term (1-10 min) activation treatment with dilute hydrochloric acid (3-10 wt%) has a purpose far beyond cleaning. It can gently and effectively dissolve or modify the inherent passivation film (mainly Cr2O3) on the stainless steel surface, exposing the highly active surface of Fe, Cr, and Ni atoms and generating micro-roughness. This greatly improves the wettability of the subsequent ceramic melt to the metal and provides the optimal initial interfacial state for element interdiffusion and interfacial chemical reactions during the Joule heating process.

[0021] Secondly, it lies in the preparation of the slurry, ball milling to D... 90 With a particle size of ≤5 μm, the aim is to obtain fine particles with high specific surface area and reactivity. Fine powder not only facilitates the formation of stable and uniform slurries in organic solvents, ensuring uniform coating of fibers and appropriate penetration into shallow pores during dip coating, but more importantly, it can be heated to a molten or semi-molten state more quickly and uniformly under subsequent Joule heating, which is the material basis for achieving instantaneous reaction and uniform coating.

[0022] Thirdly, and most importantly, is the Joule heat treatment. The coated and surface-dried precursor is connected to a circuit, and a current of 70–90 A is applied for 5–20 seconds under a protective atmosphere. During this process, the current flows through the conductive 316L stainless steel fiber network, generating intense Joule heat. This causes the fibers and the basalt powder attached to their surface to undergo a rapid temperature rise from room temperature to high temperature within seconds. This non-equilibrium rapid heating provides a strong kinetic driving force for the interfacial reaction. At the instantaneous high temperature, the surface of the basalt powder softens or low-melting-point components melt, and the resulting melt rapidly wets the activated metal surface. The high temperature also stimulates intense interfacial element diffusion. Elements such as Fe and Cr in the stainless steel diffuse into the coating, while elements such as Si, O, and Al in the basalt diffuse into the metal surface. Interfacial chemical reactions occur during this process; for example, Fe reacts with SiO2 to form fir olivine (Fe2SiO4), or Fe, Cr, and O form a complex (Fe,Cr)3O4 type spinel solid solution. These reactions form an extremely thin (nanometer to submicron) metallurgical reaction transition layer at the interface, with a gradient in composition and structure. This transition layer, like a "chemical weld," achieves a strong bond between the coating and the substrate at the atomic / molecular scale. Its bonding strength far exceeds that of traditional physical-mechanical anchoring. Furthermore, due to heat conduction from the inside to the outside of the metal fibers, the basalt powder attached to the fibers experiences a temperature gradient that decreases from the inside out. The powder near the fiber surface melts most fully, forming a continuous and dense "anchoring layer" upon cooling. Its primary function is to achieve the strongest interfacial bonding and isolate corrosive media. The outer powder layer experiences relatively lower heating, primarily consisting of interparticle sintering necks, retaining more porosity and forming a "functional filter layer" with three-dimensional interconnected channels. This naturally formed "dense-porous" gradient structure in one step is the ingenious aspect of this solution.

[0023] The fourth method is based on Joule heat treatment. After the current is applied, the molten coating solidifies rapidly in a very short time (seconds) thanks to the high thermal conductivity of the metal skeleton and the cooling effect of the environment. This rapid cooling process effectively inhibits excessive grain growth, which is conducive to the formation of fine-grained or even amorphous structures in the coating, thereby improving the coating's hardness, toughness, and thermal stability. It also helps to "freeze" the favorable interface structure formed at high temperatures, alleviating the internal stress caused by the mismatch between cooling and shrinkage, ultimately resulting in a porous metal-ceramic composite material.

[0024] The beneficial effects of this invention are as follows: By using Joule heat-induced instantaneous interfacial metallurgical reaction, the traditional weak physical bonding is transformed into a strong chemical metallurgical bonding, fundamentally solving the core problem of easy cracking and peeling of ceramic coatings under thermal stress and fluid erosion. This significantly improves the long-term service reliability of composite materials under dynamic and harsh working conditions. The unique "one-step" gradient structure design allows the material to almost completely retain the high throughput and low pressure drop advantages of the metal skeleton while improving filtration accuracy through the porous ceramic layer on the surface. The dense anchoring layer ensures excellent corrosion resistance and high-temperature oxidation resistance, breaking the traditional performance trade-off between "throughput-accuracy-corrosion resistance". The overall composite material inherits the excellent toughness, impact resistance and thermal shock resistance of the metal skeleton. At the same time, the surface strengthening effect of the ceramic coating improves wear resistance, overcoming the shortcomings of high brittleness and easy failure of all-ceramic filter membranes. It is suitable for complex and variable industrial environments, and the core processing only takes tens of seconds, with extremely low energy consumption, no need for complex and expensive equipment, and a simple process flow. The low cost and wide availability of basalt as a raw material give this technology a significant advantage in large-scale industrial production and cost competitiveness. Attached Figure Description

[0025] Figure 1 SEM characterization of the sample prepared in Example 1 of this invention. Figure 1 ; Figure 2 SEM characterization of the sample prepared in Example 1 of this invention. Figure 2 ; Figure 3 This is a SEM image of the experimental group sample in Example 2 of the present invention, in which the mass ratio of basalt powder to anhydrous ethanol is 1:0.6. Figure 4 The image shows the SEM characterization of the experimental group sample in Example 2 of this invention, where the mass ratio of basalt powder to anhydrous ethanol is 1:0.2. Figure 5 This is a SEM characterization image of the sample obtained in Example 4 of the present invention. Detailed Implementation

[0026] The present invention will be further described clearly and in detail below with reference to specific embodiments and the accompanying drawings. Those skilled in the art will be able to implement the present invention based on these descriptions. Furthermore, the embodiments of the present invention described below are generally only some, not all, of the embodiments of the present invention. Therefore, all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0027] Unless otherwise specified, the raw materials used in the embodiments of the present invention are all commercially available or obtainable by those skilled in the art; unless otherwise specified, the methods used in the embodiments of the present invention are all methods mastered by those skilled in the art. Example 1

[0028] A porous metal-ceramic composite material is prepared by the following method: 1) 316L stainless steel sintered fiber felt with a thickness of 0.3 mm and a porosity of about 80% was selected as the matrix. It was placed in acetone and anhydrous ethanol for 10 min of ultrasonic cleaning to remove surface oil and organic residues. Then it was immersed in 7 wt% hydrochloric acid aqueous solution for 5 min for activation treatment. After that, it was rinsed with deionized water until neutral and dried at 60 ℃ for 2 h to obtain pretreated 316L stainless steel sintered fiber felt. 2) Place basalt powder in a planetary ball mill and ball mill it to D. 90 ≤5 μm, then mix it with anhydrous ethanol at a mass ratio of 1:1, stir it on a magnetic stirrer at about 400 rpm for 60 min, and then place it in an ultrasonic cleaner for ultrasonic dispersion for 30 min to obtain ceramic slurry; 3) The pretreated 316L stainless steel sintered fiber felt obtained in step 1) is immersed in the ceramic slurry obtained in step 2) for dip coating. The vacuum is drawn to about 1 Pa and left to stand for about 5 min. Then it is taken out and left to stand at room temperature for 30 min to allow the solvent to fully evaporate. Then it is dried at 60 ℃ for 15 min to obtain the metal-ceramic composite precursor. 4) Connect the metal-ceramic composite precursor to the power electrode and generate Joule heating in an argon atmosphere using the resistance of the metal fiber matrix itself. Control the power parameters (80 A current for 10 s in this example) to rapidly heat the matrix, causing the attached ceramic powder to melt quickly and wet the surface of the metal fiber. After cooling, a ceramic coating is formed in situ on the surface of the metal fiber to obtain a porous metal-ceramic composite material.

[0029] The obtained porous metal-ceramic composite material samples were subjected to tests on their microstructure, gas flux, and pore size. The microscopic characterization results are as follows: Figure 1 and Figure 2 As shown, it can be seen that it forms a stable load on the surface of stainless steel fiber and further forms a smaller microporous structure on the surface. That is, the basalt melt phase forms a continuous protective layer on the surface of 316L stainless steel fiber, while the original three-dimensional interconnected pore structure of the metal skeleton remains basically intact.

[0030] The pure gas flux of the porous metal-ceramic composite sample measured at 25 °C was approximately 650 m·h. -1 ·kPa -1The overall effective pore size of the mesh is approximately 15 μm, indicating that it still exhibits the high-throughput characteristics typical of 316L sintered felt.

[0031] High-temperature corrosion tests were conducted on the porous metal-ceramic composite material samples: oxidation was performed at 600 °C in an atmospheric atmosphere for 30 h, with an oxidation weight gain of less than 2%. The samples were then heated to 500 °C in a tube furnace and subjected to sulfidation corrosion with a 5% (v / v) H₂S mixture; the weight gain was less than 1% after 20 h. These results demonstrate that the composite material, while maintaining high throughput and a large effective pore size, exhibits significantly improved high-temperature oxidation and sulfidation corrosion resistance, verifying the effective protective effect of the ceramic protective layer constructed in this invention on 316L sintered felt. Example 2

[0032] A porous metal-ceramic composite material is prepared by the following method: 1) 316L stainless steel sintered fiber felt with a thickness of 0.3 mm and a porosity of about 80% was selected as the matrix. It was placed in acetone and anhydrous ethanol for 10 min of ultrasonic cleaning to remove surface oil and organic residues. Then it was immersed in 7 wt% hydrochloric acid aqueous solution for 5 min for activation treatment. After that, it was rinsed with deionized water until neutral and dried at 60 ℃ for 2 h to obtain pretreated 316L stainless steel sintered fiber felt. 2) Place basalt powder in a planetary ball mill and ball mill it to D. 90 ≤5 μm, then mix it with anhydrous ethanol at a mass ratio of 1:(0.2~2.5), stir it on a magnetic stirrer at about 400 rpm for 60 min, and then place it in an ultrasonic cleaner for ultrasonic dispersion for 30 min to obtain ceramic slurry; 3) The pretreated 316L stainless steel sintered fiber felt obtained in step 1) is immersed in the ceramic slurry obtained in step 2) for dip coating. The vacuum is drawn to about 1 Pa and left to stand for about 5 min. Then it is taken out and left to stand at room temperature for 30 min to allow the solvent to fully evaporate. Then it is dried at 60 ℃ for 15 min to obtain the metal-ceramic composite precursor. 4) Connect the metal-ceramic composite precursor to the power electrode and generate Joule heating in an argon atmosphere using the resistance of the metal fiber matrix itself. Control the power parameters (80 A current for 10 s in this example) to rapidly heat the matrix, causing the attached ceramic powder to melt quickly and wet the surface of the metal fiber. After cooling, a ceramic coating is formed in situ on the surface of the metal fiber to obtain a porous metal-ceramic composite material.

[0033] In this example, slurries were prepared using different ratios of basalt powder and anhydrous ethanol, and the resulting products were characterized in the same manner as in Example 1. The characterization results are shown in the table below.

[0034]

[0035] The microscopic characterization results of the experimental group with a basalt powder to anhydrous ethanol mass ratio of 1:0.6 are as follows: Figure 3 As shown, the microscopic characterization results of the experimental group with a mass ratio of basalt powder to anhydrous ethanol of 1:0.2 are as follows. Figure 4 As shown. Figure 3 The results show that although the flux is reduced, the thicker, more continuous and denser ceramic layer gives the material higher retention accuracy and tighter filtration limits. Therefore, this coating amount control strategy can be used to prepare porous metal-ceramic composites with smaller pore sizes, suitable for special operating conditions or high-precision filtration requirements. However, Figure 4 The experimental group samples clearly and significantly limit the filtration use of the material, and actually produced many irregular deposits, resulting in a substantial reduction in its filtration effectiveness. While the experimental group with a basalt powder and anhydrous ethanol mass ratio of 1:2.5 exhibited a larger effective pore size and the highest gas flux, its weight gain exceeded 5% and 3.5% respectively in the same atmospheric oxidation and hydrogen sulfide corrosion experiments as in Example 1, indicating that its strengthening effect on the stainless steel fiber felt substrate was extremely limited, while the other experimental groups remained low. Example 3

[0036] A porous metal-ceramic composite material is prepared by the following method: 1) 316L stainless steel sintered fiber felt with a thickness of 0.3 mm and a porosity of about 80% was selected as the matrix. It was placed in acetone and anhydrous ethanol for 10 min of ultrasonic cleaning to remove surface oil and organic residues. Then it was immersed in 7 wt% hydrochloric acid aqueous solution for 5 min for activation treatment. After that, it was rinsed with deionized water until neutral and dried at 60 ℃ for 2 h to obtain pretreated 316L stainless steel sintered fiber felt. 2) Place basalt powder in a planetary ball mill and ball mill it to D. 90 ≤5 μm, then mix it with anhydrous ethanol at a mass ratio of 1:1, stir it on a magnetic stirrer at about 400 rpm for 60 min, and then place it in an ultrasonic cleaner for ultrasonic dispersion for 30 min to obtain ceramic slurry; 3) The pretreated 316L stainless steel sintered fiber felt obtained in step 1) is immersed in the ceramic slurry obtained in step 2) for dip coating. The vacuum is drawn to about 1 Pa and left to stand for about 5 min. Then it is taken out and left to stand at room temperature for 30 min to allow the solvent to fully evaporate. Then it is dried at 60 ℃ for 15 min to obtain the metal-ceramic composite precursor. 4) Connect the metal-ceramic composite precursor to the power electrode and generate Joule heating in an argon atmosphere using the resistance of the metal fiber matrix itself. Control the power parameters (90 A current for 30 s in this example) to rapidly heat the matrix, causing the attached ceramic powder to melt quickly and wet the surface of the metal fiber. After cooling, a ceramic coating is formed in situ on the surface of the metal fiber to obtain a porous metal-ceramic composite material.

[0037] After performing the same characterization as in Example 1, the pore size distribution test of this sample showed that the effective pore size was concentrated in the range of approximately 30 μm. Compared with Example 1, the gas flux of this sample was increased to approximately 800 m·h. -1 ·kPa -1 This method is suitable for applications that balance a certain level of retention accuracy with high throughput. It is evident that high current and a longer Joule heat treatment can effectively achieve ceramic layer shrinkage, which is of significant importance for controlling material pore size and throughput.

[0038] In more experimental groups, it was shown that, with other conditions remaining unchanged, continuous energization for 5 seconds resulted in insufficient protection of the stainless steel fiber felt matrix when the current was ≤75 A. However, Joule heat treatment sintering was effectively achieved when the current was ≥80 A, i.e., within the range of 80–95 A. The 95 A / 5 s experimental group was somewhat unusual, exhibiting a slightly uneven surface and cross-sectional thickness and a rough boundary structure. To further verify this, the following Example 4 experiment was conducted. Example 4

[0039] A porous metal-ceramic composite material is prepared by the following method: 1) 316L stainless steel sintered fiber felt with a thickness of 0.3 mm and a porosity of about 80% was selected as the matrix. It was placed in acetone and anhydrous ethanol for 10 min of ultrasonic cleaning to remove surface oil and organic residues. Then it was immersed in 7 wt% hydrochloric acid aqueous solution for 5 min for activation treatment. After that, it was rinsed with deionized water until neutral and dried at 60 ℃ for 2 h to obtain pretreated 316L stainless steel sintered fiber felt. 2) Place basalt powder in a planetary ball mill and ball mill it to D. 90≤5 μm, then mix it with anhydrous ethanol at a mass ratio of 1:1, stir it on a magnetic stirrer at about 400 rpm for 60 min, and then place it in an ultrasonic cleaner for ultrasonic dispersion for 30 min to obtain ceramic slurry; 3) The pretreated 316L stainless steel sintered fiber felt obtained in step 1) is immersed in the ceramic slurry obtained in step 2) for dip coating. The vacuum is drawn to about 1 Pa and left to stand for about 5 min. Then it is taken out and left to stand at room temperature for 30 min to allow the solvent to fully evaporate. Then it is dried at 60 ℃ for 15 min to obtain the metal-ceramic composite precursor. 4) Connect the metal-ceramic composite precursor to the power electrode and generate Joule heating in an argon atmosphere using the resistance of the metal fiber matrix itself. Control the power parameters (100 A current for 10 s in this example) to rapidly heat the matrix, causing the attached ceramic powder to melt quickly and wet the surface of the metal fiber. After cooling, a ceramic coating is formed in situ on the surface of the metal fiber to obtain a porous metal-ceramic composite material.

[0040] The characterization results of the sample prepared in this example are as follows: Figure 5 As shown, the viscosity of the basalt melt decreased significantly, and the coating exhibited obvious over-melting and flow, resulting in a very obvious uneven thickness and rough boundary structure on the surface and cross-section. This over-spreading leaves shrinkage pores, local coarse-grained regions, and compositional segregation areas within the coating. During subsequent cooling, the large temperature gradient leads to the accumulation of high thermal stress, easily causing microcracks and interfacial micro-debonding. At the same time, excessive fluidity may also cause the melt to excessively enter the pores, forming narrow gaps and providing conditions for subsequent crevice corrosion; some fibers may experience localized overheating under high current, which may also weaken their corrosion resistance. Therefore, there is a risk of failure during long-cycle high-temperature filtration. This example, combined with Example 3, shows that the current intensity should not be increased indefinitely; a trade-off must be made between coating density and structural integrity.

[0041] Therefore, in multiple comparative experiments, the method of the present invention requires relatively strict control of the Joule heat treatment current to be 80-90 A and the treatment time to be 5-30 s.

Claims

1. A method for preparing a porous metal-ceramic composite material, characterized in that, The method includes: 1) Using metal fiber felt as the substrate, ceramic slurry is prepared and then coated onto the surface of the metal fiber felt to form a metal-ceramic composite precursor. 2) After the metal-ceramic composite precursor is connected to the electrical system, it undergoes Joule heat treatment to generate resistance heat, thereby obtaining a porous metal-ceramic composite material.

2. The method for preparing a porous metal-ceramic composite material according to claim 1, characterized in that, Step 1) The metal fiber felt is stainless steel fiber felt; The stainless steel fiber felt is pretreated before use.

3. The method for preparing a porous metal-ceramic composite material according to claim 2, characterized in that, The pretreatment includes cleaning and activation; The activation solution used for activation is a 3-10 wt% hydrochloric acid aqueous solution, and the activation treatment time is 1-10 min; After activation, the product is dried at 50–70 °C for 1–3 h.

4. The method for preparing a porous metal-ceramic composite material according to claim 1, characterized in that, Step 1) The ceramic slurry is made of basalt powder, ground to D... 90 After the particle size is ≤5 μm, it is mixed with an organic solvent at a mass ratio of 1:(0.6~2.0) and stirred until homogeneous.

5. A method for preparing a porous metal-ceramic composite material according to claim 1 or 4, characterized in that, Step 1) The coating process is performed by dip coating.

6. The method for preparing a porous metal-ceramic composite material according to claim 1, characterized in that, Step 2) describes the process of generating Joule heat by energizing the device. The energizing current is controlled to be 70–90 A, and the energizing time is 5–30 s.

7. A method for preparing a porous metal-ceramic composite material according to claim 1 or 6, characterized in that, Step 2) The Joule heat treatment is performed in a protective atmosphere.

8. A porous metal-ceramic composite material prepared by any one of claims 1 to 7.

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