Corrosion-resistant antibacterial gradient heterogeneous material porous membrane as well as preparation method and application thereof

Abstract

The invention discloses a corrosion-resistant antibacterial gradient heterogeneous material porous membrane as well as a preparation method and application thereof, and belongs to the field of material synthesis and processing. The preparation method comprises the following steps: firstly, manufacturing a porous metal support body by adopting pulse laser discontinuity, namely multi-stage additive manufacturing, then coating a metal oxide with an antibacterial effect on the upper surface of the porous metal support body, and preparing a nano porous metal oxide functional layer by a sintering method, so as to obtain the heterogeneous membrane material with a gradient porous structure. The preparation method disclosed by the invention has the characteristics of wide material selection, controllable pore size distribution and porosity, simple and efficient preparation mode and the like. The prepared porous membrane can be used for preparing catalyst carriers, sewage and flue gas filtering bodies, seawater desalination membranes and the like.

Description

Technical Field

[0001] The present invention belongs to the field of material synthesis and processing, and particularly relates to a corrosion-resistant and antibacterial gradient heterogeneous material porous membrane. It can be used for preparing catalyst carriers, sewage and flue gas filters, seawater desalination membranes, etc. Background Art

[0002] Due to their high porosity and rich connected pore structure morphology, porous materials can be used as components such as catalytic carriers, adsorption and filtration bodies, and membrane materials, and are widely used in the fields of environmental protection, chemical engineering, biology, medicine, etc. Porous metals are a type of porous material. Compared with porous ceramics and porous polymers, they have advantages such as better corrosion resistance, higher mechanical properties, stronger processing controllability, and a wider range of material selection, and are more widely used in extreme environments.

[0003] The traditional preparation methods of porous metal materials mainly include the pore-forming agent method, powder sintering method, foaming method, template method, etc. For example, a preparation method for preparing gradient porous metal by powder sintering disclosed in Chinese Patent Application Publication No. CN119076951A. The thickness of the porous gradient layer does not exceed 100 μm, and the surface pore size does not exceed 5 μm. The product has the characteristics of high flux, low cost, and easy backwashing. A preparation method of porous copper metal disclosed in Chinese Patent Application Publication No. CN118563161A. After mixing the raw materials with the pore-forming agent, through the technological processes of pressing, reduction, and removing the pore-forming agent, porous metal with adjustable surface pore size is obtained. A preparation method for improving the strength of closed-cell aluminum foam disclosed in Chinese Patent Application Publication No. CN110453159A. Based on the melt foaming preparation process, pretreated basalt fibers are added to the aluminum or aluminum alloy melt to improve the strength of the closed-cell aluminum foam in a fiber-reinforced manner. The compressive yield strength can reach 11.35 MPa, and the yield strength is increased by 1.87 times. The traditional preparation methods of porous metals have the advantages of low cost and high efficiency. However, defects such as limited structure control and difficulty in preparing complex structures restrict their further application.

[0004] Additive manufacturing, also known as 3D printing technology, is an important method for preparing porous metal materials in recent years. It realizes the efficient manufacturing of porous metal materials by layer-by-layer stacking of metal powders or wires and precisely controlling the structure and morphology under the guidance of a digital design model. The whole process has the characteristics of high precision and personalized customization. Although 3D printing technology shows different advantages in controlling the pore structure and porosity of porous metals and improving the preparation efficiency. However, the slow printing speed and low raw material utilization rate are important problems restricting its application. In addition, there are certain limitations in the preparation of heterogeneous porous membranes, controlling gradient structures, and multifunctional applications.

[0005] Microorganisms such as Staphylococcus aureus, Escherichia coli, and Streptococcus can be transmitted through air, water sources, contact, etc., and can cause serious harm to the human body. At present, the preparation of antibacterial materials is an urgent problem to be solved. The research on heterogeneous gradient structure antibacterial materials is a more novel and innovative design method. Making the heterogeneous gradient structure antibacterial materials have better durability and corrosion resistance, so as to show a broader application scope in fields such as sewage treatment and catalytic filtration. Summary of the Invention

[0006] In order to prepare a membrane material with corrosion resistance and antibacterial properties, while achieving high porosity, uniform pore size distribution, and heterogeneous gradient porous structure, the present invention provides a porous membrane of a corrosion-resistant and antibacterial gradient heterogeneous material.

[0007] The present invention also provides a preparation method and application of this porous membrane of corrosion-resistant and antibacterial gradient heterogeneous material.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is:

[0009] A porous membrane of a corrosion-resistant and antibacterial gradient heterogeneous material, characterized in that it is a heterogeneous membrane material composed of a porous metal support with corrosion resistance and uniform pore size distribution and a nanoscale metal oxide porous functional layer with high porosity, narrow pore size distribution, and excellent antibacterial properties. This heterogeneous membrane material has a gradient porous structure, with a porosity of 25-30%, a pore size distribution range of 500-800 nm, and an antibacterial rate range of 60%-80%.

[0010] Furthermore: The porous metal support is composed of a multi-element / high-entropy alloy composed of one or more of corrosion-resistant metals such as stainless steel, nickel, titanium, aluminum, and copper; the porous functional layer is composed of one or more of metal oxides with antibacterial effects such as silver oxide, nano-copper oxide, and nano-titanium dioxide.

[0011] The preparation method of the above-mentioned porous membrane of corrosion-resistant and antibacterial gradient heterogeneous material is divided into two major parts:

[0012] First, a porous metal support is fabricated by pulsed laser discontinuity, that is, multi-level additive manufacturing. It is required that as the number of cladding levels increases, the thickness of the additive and the cladding parameters decrease in a gradient manner, and the powder raw material is a metal powder with a narrow particle size.

[0013] Then, a metal oxide with antibacterial effects is coated on the upper surface of the porous metal support, and a nanoscale metal oxide porous functional layer is prepared by a sintering method.

[0014] Furthermore: The detailed preparation method of the porous membrane of corrosion-resistant and antibacterial gradient heterogeneous material of the present invention is:

[0015] The first step: Preparation of metal raw material powder

[0016] Determine the particle size distribution range of the metal raw material powder and perform screening to obtain metal raw material powder with a narrow particle size distribution;

[0017] Step 2: Prepare gradient porous metal support material by multi-stage cladding

[0018] On the metal substrate, use pulsed laser to prepare three-level cladding layers by powder feeding type cladding, and monitor the temperature of the cladding layer during the processing to adjust the power of the pulsed laser to ensure the uniformity of the cladding process, and at the same time avoid the damage of the pore structure caused by heat accumulation. During the processing, control the thickness of the three-level cladding layer to show a trend of decreasing gradient; The parameters of the three-level pulsed laser cladding are as follows:

[0019] First level: The pulsed laser power is set in the range of (10 - 12) W, the pulse width is (5 - 10) ns, the processing frequency is (400 - 500) KHz, and the processing rate is (30 - 40) mm / s;

[0020] Second level: The pulsed laser power is set in the range of (8 - 10) W, the pulse width is (3 - 5) ns, the processing frequency is (300 - 400) KHz, and the processing rate is (20 - 30) mm / s;

[0021] Third level: The pulsed laser power is set in the range of (6 - 8) W, the pulse width is (2 - 3) ns, the processing frequency is (300 - 400) KHz, and the processing rate is (10 - 20) mm / s;

[0022] Step 3: Surface remelting of the gradient porous metal support material

[0023] Perform surface remelting on the gradient porous material prepared in the second step to increase the smoothness of the surface of the porous material and the bonding strength between powders. The power of the pulsed laser cladding is set in the range of (6 - 8) W, the pulse width is (2 - 3 ns), the processing rate is (10 - 20) mm / s, and the processing frequency of the pulsed laser cladding is set to (300 - 400) KHz;

[0024] Step 4: Preparation of antibacterial nano-porous metal oxide functional layer

[0025] Cut and separate the gradient porous metal support material from the substrate, coat the uniformly dispersed antibacterial nano-porous metal oxide slurry on the porous metal support, and perform high-temperature sintering after drying to finally obtain a porous metal support - nano-porous metal oxide gradient heterogeneous material.

[0026] Furthermore: The thickness of the first-level cladding layer is 2 - 3 mm, the thickness of the second-level cladding layer is 1 - 2 mm, and the thickness of the third-level cladding layer is 0.5 - 1 mm.

[0027] Further: when the thickness of the first-level cladding layer does not meet the requirement, the first-level cladding layer can be clad in two times, and the two cladding steps and process parameters are the same.

[0028] Further: the high temperature sintering temperature in step 4 is 600-800°C, and the insulation time is set to 8-12h; the drying temperature is 80-100°C, and the drying time is 3-5h.

[0029] Further: the on-delay of the above-mentioned pulse laser melting and remelting is set to 0μs, the off-delay is set to 100μs, the corner delay is set to 100μs, the end delay is set to 0μs, and the jump parameter is set to 2000mm / s.

[0030] The positive effects of the present invention are explained below based on the reaction and action mechanism of the present invention.

[0031] 1. The advancement of the inventive principle: The non-continuous additive manufacturing of porous metal supports using pulsed lasers can achieve precise control of heat input by adjusting parameters such as processing power, pulse width, and processing speed, avoiding the risk of excessive melting of metal materials, and achieving good control of porosity and pore structure. At the same time, the pulsed laser processing method has high speed and high flexibility, and can realize the manufacture of complex structures in a short time, and adjust the porosity, morphology and other performance characteristics of the material according to different application requirements. The coating and sintering method for preparing antibacterial nanoporous metal oxide functional layers can effectively control the thickness and uniformity of the functional layer, enhance the bonding force between the support and the functional layer, and extend its service life. In addition, the coating and sintering method has relatively simple equipment, mature technology, and certain economy and large-scale production capabilities.

[0032] 2. Advanced materials: Compared with porous ceramics and porous polymer materials, porous metal support materials have better processability and design flexibility, and combined with additive manufacturing technology, high-precision pore structure design can be achieved. In addition, porous metal support materials have excellent high-temperature stability and good corrosion resistance. They can maintain good structural and performance stability under extreme environments and have a long service life. Nano metal oxides (such as nano silver, nano copper oxide, nano zinc oxide, etc.) have unique antibacterial mechanisms such as metal ion release, high surface effect, and redox reaction. They have efficient bacterial killing ability and long-lasting antibacterial effect. At the same time, nano metal oxides can be compounded with other materials to form heterogeneous materials with antibacterial effects, improve the mechanical properties and bactericidal effects of the materials, and provide long-term antibacterial protection.

[0033] 3. Innovation of the gradient porous structure: In the porous metal support, the pores mainly originate from the micron-sized interstitial pores generated by the discontinuous action mode of pulsed laser. In the porous metal oxide functional layer, the pores mainly come from the nano-sintering pores formed by the combination of particles under high-temperature action. The gradient porous structure composed of the porous metal support and the porous nano-metal oxide functional layer takes into account both mechanical strength and functionality. The gradient structure can achieve a gradual distribution of strength and stiffness, enhancing the thermal conductivity and high-temperature resistance of the membrane material. At the same time, the porous gradient structure can realize the coordinated optimization of porosity and mechanical properties, with stronger applicability.

[0034] 4. Specificity of corrosion resistance and antibacterial effect: The synergistic effect of the porous metal support and the nano-porous copper oxide functional layer has good corrosion resistance and antioxidant ability, by optimizing the surface contact area, slowing down the accumulation of corrosive substances, and reducing the accumulation of corrosion. Nano-porous copper oxide can have good antibacterial effects through metal ion release and bactericidal action. The dual functions of corrosion resistance and antibacterial make the gradient heterogeneous material porous membrane have good environmental adaptability.

[0035] 5. The porosity of the porous metal support of the present invention was calculated by the Archimedes drainage method, and its porosity range is 30% - 35%. The porosity and pore size distribution of the antibacterial functional layer were calculated by the image method, with a porosity of 25% - 30% and a pore size distribution range of 500 - 800 nm. By culturing the gradient porous membrane in Escherichia coli culture medium for 24 h, its antibacterial rate was calculated, and the antibacterial rate range is 60% - 80%. Description of the Drawings

[0036] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. The drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0037] Figure 1 Schematic diagram of pulsed laser additive manufacturing of a porous metal support.

[0038] Figure 2 Schematic diagram of the macro-micro morphology of a porous iron-based metal material support; where 2a shows the macroscopic view, and 2b and 2c show the micro-morphology diagrams at different magnification scales.

[0039] Figure 3 Schematic diagram of the cross-section - surface morphology and multi-level structure of the gradient porous heterogeneous structure; where 3a shows the cross-section - surface morphology diagram of the stainless steel - porous iron-based metal - nano CuO gradient heterogeneous structure, and 3b shows the multi-level structure diagram.

[0040] Figure 4 It is a schematic diagram of nano-CuO and nano-Al2O3 slurries with different ratios after sedimentation for 24 h; among them, 4a is the initial slurry stratification situation, 4b is the slurry stratification situation after standing for 24 h, and 4c is the ratio of the slurry stratification thickness to the total thickness.

[0041] Figure 5 It is a comparison of the morphologies of the functional layers at different sintering temperatures, where 5a is sintered at 600 °C, 5b is sintered at 700 °C, and 5c is sintered at 800 °C.

[0042] Figure 6 It is a performance evaluation diagram of the material prepared by the present invention after culturing Escherichia coli for 24 h; among them, 6a shows the porous iron-based metal material, 6b shows the porous iron-based metal material-nano-CuO gradient heterogeneous material, and 6c shows the porous iron-based metal material-nano-CuO + nano-Al2O3 gradient heterogeneous material. Specific embodiments

[0043] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making the protection scope of the present invention more clearly defined.

[0044] Embodiment 1

[0045] The preparation method of the corrosion-resistant and antibacterial gradient heterogeneous material porous membrane of the present invention is as follows:

[0046] The first step: Screening of iron-based metal powder materials

[0047] Using the purchased commercial iron-based metal powder, its particle size distribution was determined to be 15 - 40 μm using a laser particle size analyzer, and the iron-based metal powder material was screened using a 600-mesh sieve to remove large-size powders, obtaining iron-based metal powder with an average particle size of 20 - 25 μm.

[0048] The second step: Preparation of gradient porous metal support materials

[0049] 2.1: Preparation of the first cladding layer of porous iron-based metal materials

[0050] Iron-based metal powder with an average particle size of 20 - 25 μm was evenly coated on a structural steel substrate. The thickness of the powder layer was controlled to be 3 mm, and the length and width of the powder layer were 15 mm each. The distance from the laser source to the powder layer was controlled to be 20 cm. The laser processing power was adjusted to 10 W, the pulse width was 10 ns, the processing frequency was set to 400 KHz, and the processing speed was set to 40 mm / s. The turn-on delay was set to 0 μs, the turn-off delay was set to 100 μs, the corner delay was set to 100 μs, and the end delay was set to 0 μs. The jump parameter was set to 2000 mm / s. The laser processing mode was set to be from top to bottom, in a zigzag processing mode, and the line spacing of the processing was set to 0.05 mm. During the processing, a non-contact temperature measurement method was used to monitor the temperature of the powder layer to avoid the thermal accumulation effect generated during the reaction. The thickness of the sample after processing reached 1.5 mm. Due to the characteristics of pulsed laser non-continuous processing, the sample presented a porous structure.

[0051] 2.2: Preparation of the second-level cladding layer of porous iron-based metal material

[0052] After the preparation of the first-level cladding layer was completed, it was cooled at room temperature for 30 min. After using a thermometer to detect that the temperature of the sample reached room temperature, the preparation of the second-level cladding layer was carried out. The thickness of the powder layer was controlled to be 2 mm, and the length and width of the powder layer were 15 mm each. The laser processing power was adjusted to 8 W, the pulse width was 3 ns, the processing frequency was 300 KHz, and the processing speed was set to 20 mm / s. The turn-on delay was set to 0 μs, the turn-off delay was set to 100 μs, the corner delay was set to 100 μs, and the end delay was set to 0 μs. The jump parameter was set to 2000 mm / s. The laser processing mode was set to be from top to bottom, in a zigzag processing mode, and the line spacing of the processing was set to 0.05 mm. During the processing, a non-contact temperature measurement method was also used to monitor the temperature of the powder layer.

[0053] 2.3: Preparation of the third-level cladding layer of porous iron-based metal material

[0054] After the preparation of the second-level cladding layer is completed, it is cooled at room temperature for 30 minutes. After using a thermometer to detect that the temperature of the sample reaches room temperature, the preparation of the third-level cladding layer is carried out. Control the powder spreading layer thickness to be 1 mm, and the length and width of the powder spreading layer are 15 mm respectively. Adjust the laser processing power to 6 W, the pulse width to 2 ns, the processing frequency to 300 KHz, and the processing speed is set to 10 mm / s. The switch-on delay is set to 0 μs, the switch-off delay is set to 100 μs, the corner delay is set to 100 μs, and the end delay is set to 0 μs. The jump parameter is set to 2000 mm / s. The laser processing method is set to process from top to bottom in a zigzag pattern, and the line spacing during processing is set to 0.05 mm. During the processing, the non-contact temperature measurement method is also used to monitor the temperature of the powder spreading layer. To reduce the thermal accumulation effect on the product surface, the laser processing method is set to process from outside to inside in a "return" shape pattern, and the line spacing is set to 0.05 mm. During the processing, the non-contact temperature measurement method is also used to monitor the temperature of the powder spreading layer.

[0055] Step 3: Surface remelting of the porous iron-based metal material

[0056] The porous metal iron-based material manufactured by pulsed laser additive manufacturing in the fourth step is subjected to surface remelting to enhance the bonding strength between powders and mechanical properties. Adjust the laser remelting power to 6 W, the pulse width to 2 ns, the remelting frequency to 300 KHz, and the remelting processing speed is set to 10 mm / s. Finally, a porous iron-based metal support material with a length of 15 mm, a width of 15 mm, and a height of 2 mm can be obtained.

[0057] Step 4: Preparation of a porous nano-CuO functional layer on the porous iron-based metal material

[0058] 4.1: Preparation of the porous nano-CuO slurry

[0059] The raw material of nano-CuO is a commercially available powder purchased, with a flaky shape and an average particle size of 20 nm. 12 g of nano-CuO, 0.6 g of sodium hexametaphosphate, and 9 g of polyethylene glycol are incorporated into 78.4 g of deionized water, and stirred with a planetary ball mill at a speed of 250 r / min for 12 h to obtain a nano-CuO slurry with good dispersion and strong fluidity. Subsequently, the slurry is treated with a vacuum pump and ultrasonic treatment to eliminate the bubbles in the slurry.

[0060] 4.2: Sintering of the porous nano-CuO functional layer

[0061] The nano-CuO slurry prepared in step 4.1 was coated in the porous iron-based metal material support layer by spin coating and dried in an oven at 80 °C for 4 h. Subsequently, the dried sample was subjected to high-temperature sintering in a box furnace. The initial temperature was set at 20 °C, the heating rate was set at 2 °C / min, heated to 800 °C, and held at 800 °C for 12 h to increase the bonding force between the nano-CuO functional layer and the porous iron-based metal material support, and finally a porous iron-based metal material-nano-CuO gradient material was obtained.

[0062] The schematic diagram of the pulsed laser additive manufacturing of the porous metal support is as Figure 1 shown. Porous metals are prepared by utilizing the discontinuity of the pulsed laser energy action mode.

[0063] To verify the positive effects of the present invention, after the additive manufacturing of the porous iron-based metal material, it was cut from the substrate using a wire cutting tool, and then the material structure morphology and properties were detected. The macroscopic morphology of the porous iron-based metal material support is as shown in the appendix Figure 2 shown. It was found that after additive manufacturing, no cracking or deformation occurred in the porous material, proving its good mechanical strength and stability. The microscopic morphology of the porous iron-based metal material shows obvious pore structures, and physical interstitial pores are formed between the reactant particles after laser cladding.

[0064] Subsequently, the nano-CuO coating liquid was coated on the porous iron-based metal material support to prepare a gradient heterogeneous structure porous material, and the cross-section and surface schematic diagrams are as Figure 3 shown. It can be seen from the figure that the stainless steel matrix is a dense structure, the pore size distribution of the porous iron-based metal material support part is about 50-100 μm, and the pore size of the nano-CuO film layer is about 500 nm. The gradient heterogeneous porous structure can achieve the filtration and separation of impurities in sewage.

[0065] Example 2

[0066] The screening of the iron-based metal powder material, the preparation of the gradient porous metal support material, and the surface remelting step of the porous iron-based metal material in Example 2 are the same as those in Example 1. The difference is that in step four, to further explore the influence of the functional layer slurry on enhancing the thermal stability of the functional layer and the antibacterial performance of the coating, different components of Al2O3 were added to the nano-CuO raw material in Example 1 and compared with Example 1 (that is, the first group in Table 1).

[0067] Step 4: Preparation of a porous nano-CuO + Al2O3 functional layer on the porous iron-based metal material

[0068] 4.1: Preparation of the porous nano-CuO + Al2O3 slurry

[0069] The nano-CuO raw material is a commercially purchased powder in the form of lamellae with an average particle size of 20 nm. The nano-Al2O3 is a commercially purchased powder in the form of spheres with an average particle size of 20 nm. To determine the slurry ratio with the best stability, four groups of nano-CuO + Al2O3 slurries were prepared according to the ratios in the second to fifth groups in Table 1 and compared with the first group, i.e., Example 1. During implementation, the well-mixed slurry was stirred at a speed of 250 r / min for 12 h using a planetary ball mill to obtain a nano-CuO + Al2O3 slurry with good dispersibility and strong fluidity. Subsequently, the slurry was treated using a vacuum pump and ultrasonic treatment to remove the bubbles in the slurry. Then, the mixed slurry was allowed to stand for 24 h, and its delamination thickness was observed and calculated. The experimental results are as Figure 4 shown. The delamination thickness ratio of the second group of samples in the figure is only 2.7%, with good fluidity and uniformity. Therefore, the second group was selected as the nano-CuO + Al2O3 slurry.

[0070] Table 1 Nano-CuO + Al2O3 slurry ratio

[0071] Nano CuO <![CDATA[Nano-Al2O3]]> Sodium hexametaphosphate Polyethylene glycol Deionized water The first group 12wt.% 0 0.6wt.% 9wt.% 78.4wt.% The second group 9wt.% 3wt.% 0.6wt.% 9wt.% 78.4wt.% The third group 6wt.% 6wt.% 0.6wt.% 9wt.% 78.4wt.% The fourth group 3wt.% 9wt.% 0.6wt.% 9wt.% 78.4wt.% The fifth group 0 12wt.% 0.6wt.% 9wt.% 78.4wt.%

[0072] 4.2: Sintering of the porous nano-CuO + Al2O3 functional layer

[0073] The nano-CuO + Al2O3 slurry prepared in the second group in step 4.1 was coated on the porous iron-based metal material support layer by spin coating and dried in an oven at 80 °C for 4 h. Subsequently, the dried sample was subjected to high-temperature sintering in a box furnace. The initial temperature was set at 20 °C, and the heating rate was set at 2 °C / min. The temperature was raised to 600 / 700 / 800 °C respectively and held at the corresponding temperature for 12 h to increase the bonding force between the nano-CuO + Al2O3 functional layer and the porous iron-based metal material support. The morphology of the functional layer was observed using a scanning electron microscope, and the optimal sintering temperature was determined. The microscopic morphology of the functional layer is as Figure 5 shown. It can be seen from Figure 5 that as the sintering temperature increases, the pore diameter of the functional layer gradually decreases, and no cracking phenomenon occurs. Moreover, nano-Al2O3 fills the voids between nano-CuO, reducing the average pore diameter of the functional layer, thereby improving the filtration efficiency of the material. It can also be seen from Figure 5 that 800 °C is the optimal temperature for preparing a defect-free functional layer. Finally, a porous membrane porous iron-based metal material-nano-CuO gradient material with a narrow pore size distribution suitable for filter catalyst carriers, sewage and flue gas filters, and seawater desalination membranes was obtained.

[0074] To investigate the effect of adding Al2O3 to the functional layer raw material on the antibacterial performance of the porous metal iron-based material-nano-CuO membrane material. The samples were placed in a petri dish containing Escherichia coli, and the survival rate of Escherichia coli was detected after 24 h. The experimental results are asFigure 6 As shown. The results show that, compared with Example 1, although adding Al2O3 to the functional layer slurry will affect the antibacterial performance of the gradient heterogeneous structure porous material, the antibacterial performance is still far better than that of the porous iron-based metal material. In practice, it is necessary to adjust the material components in the functional layer raw materials according to the requirements for the coating performance, which is not difficult for those skilled in the art to do.

[0075] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be thought of without creative work should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope defined by the claims.

Claims

1. A porous membrane of a corrosion-resistant and bacteriostatic gradient heterogeneous material, characterized in that, It is a heterogeneous membrane material composed of a porous metal support body that is corrosion-resistant and has a uniform pore size distribution, and a nano-scale metal oxide porous functional layer with a narrow pore size distribution. This heterogeneous membrane material has a gradient porous structure, a porosity of 25-30%, a pore size distribution range of 500-800 nm, and an antibacterial rate range of 60%-80%.

2. The porous membrane of the corrosion-resistant and antibacterial gradient heterogeneous material according to claim 1, characterized in that, The porous metal support body is composed of a multi-element / high-entropy alloy composed of one or more of corrosion-resistant metals such as stainless steel, nickel, titanium, aluminum, and copper; the porous functional layer is composed of one or more metal oxides with antibacterial effects such as silver oxide, nano-copper oxide, and nano-titanium dioxide.

3. A method for preparing a porous membrane of a corrosion-resistant and antibacterial gradient heterogeneous material as described in claim 1 or 2, characterized in that, It is divided into two major parts overall: First, pulsed laser discontinuity, that is, multi-level additive manufacturing, is used to prepare the porous metal support body. It is required that as the number of cladding levels increases, the thickness of the additive and the cladding parameters decrease in a gradient manner. The powder raw material is selected as a metal powder with a narrow particle size. Then, a metal oxide with antibacterial effects is coated on the upper surface of the porous metal support body, and a nano-scale metal oxide porous functional layer is prepared by the sintering method.

4. A method for preparing a porous membrane of a corrosion-resistant and antibacterial gradient heterogeneous material as described in claim 3, characterized in that, The detailed preparation method is as follows: Step 1: Preparation of metal raw material powder Determine the particle size distribution range of the metal raw material powder and perform screening to obtain a metal raw material powder with a narrow particle size distribution. Step 2: Preparation of gradient porous metal support body material by multi-level cladding On the metal substrate, pulsed laser is used for powder-fed cladding to prepare a three-level cladding layer. During the processing, the temperature of the cladding layer is monitored to adjust the power of the pulsed laser to ensure the uniformity of the cladding process and avoid the damage of the pore structure caused by heat accumulation. During the processing, control the thickness of the three-level cladding layer to show a gradient decreasing trend; the pulsed laser cladding parameters for the three levels are as follows: The first level: The pulsed laser power is set in the range of (10-12) W, the pulse width is (5-10) ns, the processing frequency is (400-500) KHz, and the processing rate is (30-40) mm / s; The second level: The pulsed laser power is set in the range of (8-10) W, the pulse width is (3-5) ns, the processing frequency is (300-400) KHz, and the processing rate is (20-30) mm / s; The third level: The pulsed laser power is set in the range of (6-8) W, the pulse width is (2-3) ns, the processing frequency is (300-400) KHz, and the processing rate is (10-20) mm / s; Step 3: Surface remelting of the gradient porous metal support body material The gradient porous material prepared in the second step is subjected to surface remelting to increase the smoothness of the surface of the porous material and the bonding strength between the powders. The power of the pulsed laser cladding is set in the range of (6-8) W, the pulse width is (2-3 ns), the processing rate is (10-20) mm / s, and the processing frequency of the pulsed laser cladding is set to (300-400) KHz; Step 4: Preparation of antibacterial nano-porous metal oxide functional layer The gradient porous metal support body material is cut and separated from the substrate, and the uniformly dispersed antibacterial nano-porous metal oxide slurry is coated on the porous metal support body. After drying, it is subjected to high-temperature sintering to finally obtain a porous metal support body-nano-porous metal oxide gradient heterogeneous material.

5. The preparation method of the corrosion-resistant and antibacterial gradient heterogeneous material porous membrane according to claim 4, characterized in that, The thickness of the first-level cladding layer is 2-3 mm, the thickness of the second-level cladding layer is 1-2 mm, and the thickness of the third-level cladding layer is 0.5-1 mm.

6. The preparation method of the corrosion-resistant and bacteriostatic gradient heterogeneous material porous membrane according to claim 5, characterized in that, When the thickness of the first-level cladding layer fails to meet the requirements, at this time, the first-level cladding layer is cladded in two times, and the two cladding steps and process parameters are the same.

7. The preparation method of the corrosion-resistant and antibacterial gradient heterogeneous material porous membrane according to claim 4, characterized in that The high-temperature sintering temperature in Step 4 is 600-800 °C, and the heat preservation time is set to 8-12 h; the drying temperature is 80-100 °C, and the drying time is 3-5 h.

8. The preparation method of the corrosion-resistant and antibacterial gradient heterogeneous material porous membrane according to claim 4, characterized in that, The switch-on delay of pulsed laser melting and remelting is set to 0 μs, the switch-off delay is set to 100 μs, the corner delay is set to 100 μs, the end delay is set to 0 μs, and the jump parameter is set to 2000 mm / s.

9. Application of the corrosion-resistant and bacteriostatic gradient heterogeneous material porous membrane as claimed in claim 1 or 2 in catalyst carriers, sewage and flue gas filters, and seawater desalination membranes.

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