Porous nickel plate material and preparation method thereof

Abstract

The invention relates to the technical field of metal porous material preparation, and particularly discloses a porous nickel plate material and a preparation method thereof. The preparation method comprises the steps that S1, pure nickel powder is screened and dried; s2, a ceramic plate mold is fixed, the ceramic plate mold comprises an upper cover plate, a lower cover plate and a middle frame, and the middle frame is located between the upper cover plate and the lower cover plate and used for forming a porous nickel plate; s3, the screened pure nickel powder is laid in an inner cavity of the middle frame in a loose state and scraped to be flat, and then mold closing is conducted; s4, performing loose sintering on the closed ceramic plate mold; and S5, after sintering is completed, cooling to room temperature, and demolding and separating. According to the preparation method, through the synergistic effect of powder particle size screening and a mold structure, a three-dimensional connected pore network is constructed under the condition that a pore forming agent is not needed, and the prepared porous nickel plate material has good strength and pore connectivity.

Description

Technical Field

[0001] This application relates to the field of porous metal material preparation technology, and more specifically, it relates to a porous nickel plate material and its preparation method. Background Technology

[0002] Nickel-based materials play a crucial role in modern industry due to their high melting point, excellent corrosion resistance, and good mechanical properties. With the rapid development of technology, the application scope of nickel-based materials is constantly expanding, covering numerous fields such as energy, transportation, and chemicals. For example, in the energy sector, it is used to manufacture porous electrodes for batteries, providing key support for the storage and utilization of new energy sources; in the transportation sector, it is used in fuel purifiers for vehicles (automobiles / aircraft), ensuring the efficient operation of transportation vehicles; and in the chemical sector, as an important material for industrial gas filters, it ensures the safety and stability of chemical production. These applications not only drive the development of related industries but also place higher demands on the performance and quality of nickel-based materials. Porous nickel plate materials, in particular, possess unique advantages in improving filtration efficiency and enhancing electrode performance due to their porous structure; therefore, the improvement and innovation of their preparation technology are especially important.

[0003] Currently, the commonly used methods for preparing porous nickel plate materials mainly include the pore-forming agent method, the electrochemical dealloying method, and the traditional loose-pack sintering method. The pore-forming agent method involves thoroughly mixing a pore-forming agent with nickel powder, then sintering it, and finally removing the pore-forming agent to form a porous structure. This method requires several complex steps, including pore-forming agent dispersion, powder blending, high-temperature sintering, and subsequent pore-forming agent removal. The electrochemical dealloying method relies on high-precision electrolysis equipment and requires precise control of process parameters to achieve a specific pore structure. The traditional loose-pack sintering method involves directly sintering nickel powder; the process is relatively simple, mainly relying on the natural accumulation of powder to form certain pores.

[0004] However, these existing methods have significant shortcomings. The pore-forming agent method, due to its numerous process steps, is prone to residual contamination from the pore-forming agent, affecting the quality of the porous nickel plate material. Furthermore, its pore size distribution is poorly controllable, making it difficult to meet the requirements of some applications with high pore structure requirements. The electrochemical dealloying method, relying on high-precision equipment and complex process parameter control, results in high production costs, limiting its large-scale application. The traditional loose-pack sintering method not only has strict sintering conditions but also produces sintered bodies with low strength and poor pore connectivity, failing to meet the practical requirements for fluid permeation. Summary of the Invention

[0005] To address the aforementioned technical problems, this application provides a porous nickel plate material and its preparation method.

[0006] Firstly, this application provides a method for preparing a porous nickel plate material, which adopts the following technical solution: A method for preparing a porous nickel plate material includes the following steps: S1. Sift pure nickel powder and dry it; S2. Fix the ceramic plate mold, the ceramic plate mold includes an upper cover plate, a lower cover plate and a middle frame, the middle frame is located between the upper cover plate and the lower cover plate, and is used to form a porous nickel plate; S3. Spread the sieved pure nickel powder loosely into the inner cavity of the middle frame and level it, then close the mold. S4. Loosely sinter the ceramic plate mold after it has been assembled. S5. After sintering, cool to room temperature, demold, and separate to obtain porous nickel plate material.

[0007] Preferably, in S1, the pure nickel powder is atomized spherical powder or atomized quasi-spherical powder, with an oxygen content ≤0.1% and a particle size range of 10-100μm.

[0008] Preferably, the pure nickel powder is sieved to obtain powders with multiple different particle size ranges, including 10-30μm, 30-45μm, 45-75μm and 75-100μm.

[0009] Through the above technical solution, this application first sieves pure nickel powder into powders of different particle size ranges. Then, based on the loose density of the powder, powders of different particle size ranges are selected, and combined with a self-designed ceramic plate mold, a porous nickel plate material is prepared using a sintering process. The preparation method of this application, through the synergistic effect of powder particle size screening and mold structure, constructs a three-dimensional interconnected pore network without the need for pore-forming agents. The resulting porous nickel plate material exhibits good strength and pore connectivity. This method is not only simple and easy to operate, but also possesses excellent structural control capabilities. It can prepare porous nickel plate materials with controllable single-layer thickness according to product thickness and structural design requirements, while simultaneously meeting the strength and pore connectivity requirements of different products, offering high flexibility. When preparing single-layer porous nickel plate materials, powders of corresponding particle size ranges can be selected according to the actual needs of the product. If the product already possesses good strength and pore connectivity, powders with smaller particle sizes can be selected to achieve even greater strength; conversely, powders with larger particle sizes can be selected to meet greater fluid permeability requirements.

[0010] The specific method for fixing the ceramic plate mold in this application is as follows: First, clean the mold surface using a steel brush; second, apply adhesive evenly to the bonding surface of the middle frame; finally, assemble and fix the lower cover plate and the adhesive-coated middle frame. The adhesive must be applied evenly and in a thin layer to ensure no gaps between the middle frame and the lower cover plate, preventing uneven powder layering due to gaps. The adhesive used is ethyl cyanoacrylate adhesive (502 glue), which completely evaporates during the subsequent sintering process.

[0011] During the transfer process after the ceramic plate mold is closed, it must always remain in a horizontal position, and any form of shaking or tilting is strictly prohibited. After sintering, once the temperature inside the sintering furnace has dropped to room temperature, the sintered porous nickel plate is demolded from the ceramic plate mold to obtain a porous nickel plate material with a good pore structure. The pore structure of the porous nickel plate material in this application is formed entirely spontaneously through loose-pack sintering, without the addition of any pore-forming agent. Its preparation process omits the pore-forming step and the subsequent removal of the pore-forming agent, which not only solves the problem of residual pore-forming agent pollution but also significantly simplifies the production process.

[0012] Depending on the end-use requirements of the product, the porous nickel plate material of this application can also be surface modified by appropriate post-processing techniques, such as electroless nickel plating to increase strength, or acid etching to enlarge the pore size.

[0013] It should also be emphasized that this application uses pure nickel powder only for preparing porous nickel plate materials. Other metal powder materials, including but not limited to copper, iron, titanium, stainless steel, and other alloy powders, may also be used to prepare other porous metal plate materials. Metal plate materials prepared using these metal powder materials according to the preparation method of this application are also within the scope of protection of this application.

[0014] Preferably, in step S1, the sieved pure nickel powder is mixed with 316 stainless steel powder.

[0015] By adopting the above technical solution, this application mixes 316 stainless steel powder with sieved pure nickel powder, which can further improve the strength of the porous nickel plate. The amount of 316 stainless steel powder added is adjusted according to the required strength of the porous nickel plate. The 316 stainless steel powder is an atomized spherical powder with an oxygen content ≤0.1%.

[0016] Preferably, in step S2, the number of intermediate frames is ≥1.

[0017] By adopting the above technical solution, this application can precisely control the filling structure of different pure nickel powders by stacking multiple intermediate frames of different thicknesses. During sintering, this allows for the integrated molding of a porous nickel plate with a firmly bonded interface and a double- or multi-layered porous structure, thus providing an advanced preparation method for porous materials with gradient functions. When stacking multiple intermediate frames of different thicknesses, the principle should be followed: place the pure nickel powder with a larger particle size below the pure nickel powder with a smaller particle size.

[0018] Preferably, in step S3, after the leveling operation, the surface flatness error of the nickel powder is ≤0.1mm.

[0019] By adopting the above technical solution, this application uses a scraper to remove excess pure nickel powder along the upper surface of the middle frame, ensuring that the surface flatness error of the pure nickel powder in the inner cavity is ≤0.1mm, maintaining a good flatness. During operation, the working surface of the scraper must be a continuous smooth plane to ensure the flatness of the powder layer. Then, a fine brush is used to remove residual powder from the outer edge of the middle frame and the surface of the mold. Finally, the upper cover plate is precisely aligned with the upper end face of the middle frame, and the mold is closed.

[0020] Preferably, in step S4, the vacuum degree during sintering is ≤10Pa, the temperature is 1100-1300℃, and the time is 1-2h.

[0021] By adopting the above technical solution, this application controls the sintering environment by evacuating the furnace cavity to a negative pressure of ≤10Pa, eliminating residual gases to ensure vacuum, and suppressing the oxidation of the material. Furthermore, this application does not apply external pressure to the ceramic plate mold throughout the process, maintaining the loose packing of the powder. Simultaneously, based on the particle size distribution of the powder, the optimal temperature and time are selected for sintering. Through the coordinated control of temperature and time, controllable growth of the sintering neck and preservation of the pore structure are achieved, thereby ensuring the strength and pore connectivity of the porous nickel plate material.

[0022] Secondly, this application provides a porous nickel plate material prepared by the above-mentioned method for preparing porous nickel plate material.

[0023] In summary, this application has the following beneficial technical effects: 1. The preparation method of this application does not require the addition of pore-forming agents, which eliminates the risk of chemical residue pollution from the source, reduces raw material costs, and simplifies the process flow; 2. The preparation method of this application constructs a three-dimensional interconnected pore network without the need for a pore-forming agent by screening powder particle size, controlling calcination temperature and time, and synergistic effect of mold structure. The resulting porous nickel plate material not only has good strength, but its permeability is also significantly better than the closed-pore structure of the traditional pressing-sintering process, so that the porous nickel plate material can achieve the effect of improving permeability in the fields of gas-liquid filtration and separation. 3. The preparation method of this application can not only prepare porous nickel plate materials with adjustable single-layer thickness, but also prepare integrated double-layer or multi-layer porous nickel plate materials with strong interfacial bonding by stacking intermediate frames of different thicknesses. It has high flexibility and provides an advanced preparation route for porous materials with gradient functions. Attached Figure Description

[0024] Figure 1 This is a scanning electron microscope image of the powder morphology of the pure nickel powder raw material of this application; Figure 2 This is a structural schematic diagram of the ceramic plate mold of this application; Figure 3 This is a scanning electron microscope image of the surface of the porous nickel plate prepared in Example 1 of this application; Figure 4 This is a scanning electron microscope (SEM) image of the surface of the porous nickel plate prepared in Example 2 of this application; Figure 5 This is a scanning electron microscope image of the surface of the double-layer porous nickel plate prepared in Example 3 of this application; Figure 6 This is a surface electron microscope scan of the porous nickel plate prepared in Example 4 of this application. Detailed Implementation

[0025] The technical solution of this application will be clearly and completely described below with reference to the accompanying drawings and embodiments, which can enable those skilled in the art to have a more comprehensive understanding. The specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0026] like Figure 1 As shown, the pure nickel powder of this application is a gas-atomized spherical powder or a gas-atomized spherical powder, with a purity > 99.7 wt%, an oxygen content ≤ 0.1%, and a particle size range of 10-100 μm; in the specific embodiments of this application, the pure nickel powder is a gas-atomized spherical powder.

[0027] The pure nickel powder of this application, after sieving, yields powders with multiple different particle size ranges, including 10-30 μm, 30-45 μm, 45-75 μm, and 75-100 μm. When preparing single-layer porous nickel plate materials, powders within the corresponding particle size range can be selected according to the actual needs of the product. If the product already possesses both good strength and pore connectivity, powders with smaller particle sizes can be selected if stronger strength is desired; conversely, powders with larger particle sizes can be selected if greater fluid permeability requirements are desired. In a specific embodiment of this application, powders with particle size distributions of 10-30 μm and 75-100 μm are used as examples in the preparation of single-layer porous nickel plate materials.

[0028] The 316 stainless steel powder of this application is an atomized spherical powder with an oxygen content ≤0.1% and a particle size range of 15-45μm. In the specific embodiments of this application, the weight ratio of 316 stainless steel powder to pure nickel powder is 1:9, and the addition ratio of 316 stainless steel powder can be adjusted according to actual needs.

[0029] A schematic diagram of the ceramic plate mold in this application is shown below. Figure 2 As shown, the device includes an upper cover plate, a lower cover plate, and a middle frame. The middle frame is located between the upper and lower cover plates and is used to form a porous nickel plate. The dimensions and thickness of the upper cover plate, lower cover plate, and middle frame can be flexibly designed and adjusted according to the actual size requirements of the product, as long as the size is sufficient to fit into the furnace for sintering. In a specific embodiment of this application, the dimensions of the upper and lower cover plates are both 100mm×100mm to 150mm×150mm, and the thickness is 3-5mm. The outer contour dimensions of the middle frame are 100mm×100mm to 150mm×150mm, the inner frame dimensions are 70mm×70mm to 90mm×90mm, and the thickness is 0.20-1.00mm.

[0030] Example 1 A method for preparing a porous nickel plate material includes the following steps: S1. The spherical pure nickel powder prepared by gas atomization is sieved, and pure nickel powder with a particle size range of 10-30 μm is selected, with a loose packing density of 4.63±0.05 g / cm³. 3 Then, the pure nickel powder in this particle size range is dried. S2. Prepare a ceramic plate mold. The dimensions of the upper and lower cover plates are both 110mm×110mm×4.5mm. The outer contour of the middle frame is 110mm×110mm, the inner frame is 75mm×75mm, and the thickness is 0.5mm. Fixing the ceramic plate mold: First, clean the mold surface using a steel brush; second, apply ethyl cyanoacrylate adhesive (502 glue) evenly to the bonding surface of the middle frame; finally, assemble and fix the mold by aligning and fixing the lower cover plate and the glued middle frame. S3. The sieved pure nickel powder is loosely packed into the inner cavity of the middle frame. Then, the excess pure nickel powder is scraped off along the upper surface of the middle frame with a scraper to ensure that the surface flatness error of the pure nickel powder is ≤0.1mm. During operation, the working surface of the scraper must be a continuous smooth plane to ensure the flatness of the powder layer. Then, the residual powder on the outer edge of the middle frame and the surface of the mold is removed with a fine brush. Finally, the upper cover plate is precisely aligned with the upper end face of the middle frame and the mold is closed. During the transition process after the mold is closed, the ceramic plate mold must always be kept in a horizontal translation state and any form of shaking or tilting is strictly prohibited. S4. Evacuate the sintering furnace cavity to a negative pressure of ≤10Pa to remove residual gas and ensure vacuum level, inhibit material oxidation. Do not apply external pressure to the ceramic plate mold throughout the process, maintain the loose state of powder, sinter at 1100℃, and hold for 2 hours. Under these sintering conditions, sintering necks are formed and grow between fine nickel powder particles, which increases the strength of the porous nickel plate material, while maintaining controllable porosity, thus achieving synergistic optimization of strength and pore structure. S5. After sintering, once the temperature inside the sintering furnace has decreased to room temperature, the sintered porous nickel plate is demolded from the mold to obtain the porous nickel plate material. Samples of this porous nickel plate material are taken, and scanning electron microscopy (SEM) is used to characterize the three-dimensional distribution of pores and the growth morphology of sintered necks between particles, evaluating the pore network topology. The surface SEM image is shown below. Figure 3 As shown.

[0031] from Figure 3 It can be seen that the material possesses a uniform and diffuse porous structure. The pores are interconnected in three-dimensional space, forming an open and well-distributed network of channels. On the observation plane, the pore size is distributed between 10-60 μm, covering a wide range and forming a well-connected pore network, which facilitates the formation of a multi-scale porous structure. Calculations show that its planar porosity reaches 18.6%, a high value indicating ample pore space within the material.

[0032] More significantly, the sintered necks between the nickel powder particles are noticeably long. The ratio of neck width to the original particle size can reach 1 / 3 to 1 / 2, and the particles form a strong metallurgical bond through the sintered necks, without obvious cracks or separation. These sintered necks, resembling sturdy "bridges," firmly weld adjacent particles together, forming a strong and tough three-dimensional skeleton. It is this combination of well-grown sintered necks and a highly porosity network structure that enables this porous nickel plate to possess both abundant porosity and high mechanical strength, thus ensuring sufficient support capacity as a functional material or supporting structure.

[0033] Example 2 A method for preparing a porous nickel plate material includes the following steps: S1. The spherical pure nickel powder prepared by gas atomization is sieved, and pure nickel powder with a particle size range of 75-100μm and a loose packing density of 4.92±0.05g / cm³ is selected. 3 Then, the pure nickel powder in this particle size range is dried. S2. Prepare a ceramic plate mold. The dimensions of the upper and lower cover plates are both 110mm×110mm×4.5mm. The outer contour of the middle frame is 110mm×110mm, the inner frame is 75mm×75mm, and the thickness is 0.5mm. Fixing the ceramic plate mold: First, clean the mold surface using a steel brush; second, apply ethyl cyanoacrylate adhesive (502 glue) evenly to the bonding surface of the middle frame; finally, assemble and fix the mold by aligning and fixing the lower cover plate and the glued middle frame. S3. The sieved pure nickel powder is loosely packed into the inner cavity of the middle frame. Then, the excess pure nickel powder is scraped off along the upper surface of the middle frame with a scraper to ensure that the surface flatness error of the pure nickel powder is ≤0.1mm. During operation, the working surface of the scraper must be a continuous smooth plane to ensure the flatness of the powder layer. Then, the residual powder on the outer edge of the middle frame and the surface of the mold is removed with a fine brush. Finally, the upper cover plate is precisely aligned with the upper end face of the middle frame and the mold is closed. During the transition process after the mold is closed, the ceramic plate mold must always be kept in a horizontal translation state and any form of shaking or tilting is strictly prohibited. S4. Evacuate the sintering furnace cavity to a negative pressure of ≤10Pa to remove residual gas and ensure vacuum level, inhibit material oxidation. Do not apply external pressure to the ceramic plate mold throughout the process, maintain the powder in a loose state, sintering temperature is 1150℃, and holding time is 2h. Under these sintering conditions, sintering necks are formed and grow between fine nickel powder particles, which increases the strength of porous nickel plate material, while maintaining controllable porosity, achieving synergistic optimization of strength and pore structure. S5. After sintering, once the temperature inside the sintering furnace has decreased to room temperature, the sintered porous nickel plate is demolded from the mold to obtain the porous nickel plate material. Samples of this porous nickel plate material are taken, and scanning electron microscopy (SEM) is used to characterize the three-dimensional distribution of pores and the growth morphology of sintered necks between particles, evaluating the pore network topology. The surface SEM image is shown below. Figure 4 As shown.

[0034] from Figure 4 It can be seen that the material contains a uniformly dispersed and interconnected three-dimensional pore network. On the observation plane, the pore size ranges from 50 to 170 μm. This size distribution indicates that the material forms a continuous structure dominated by medium to large pores, providing ample channels for fluid transport or functional medium diffusion. Quantitative image analysis revealed an in-plane porosity of approximately 31.2%, confirming the high proportion of inherent pore space within the material, meeting the core pore capacity requirements of relevant applications.

[0035] Analysis of the microstructure of the sintered necks revealed that moderately grown and uniformly distributed sintered necks formed between the nickel powder particles, achieving a stable metallurgical bond and constructing a continuous and complete skeletal support network between the particles. These microstructural features enabled the material to achieve good bonding strength while maintaining a high porosity of 31.2%, effectively solving the technical challenge of balancing high porosity and mechanical strength in porous materials.

[0036] Example 3 A method for preparing a porous nickel plate material, differing from Example 1 in that it constructs a gradient double-layer structure to prepare a double-layer porous nickel plate material, specifically including the following steps: S1. The spherical pure nickel powder prepared by gas atomization is sieved, and pure nickel powder with a particle size range of 10-30 μm (its loose packing density is 4.63±0.05 g / cm³) is selected. 3 And pure nickel powder with a particle size range of 45-75 μm (its loose packing density is 4.77 ± 0.05 g / cm³). 3 Then the pure nickel powder is dried. S2. Prepare ceramic plate molds. The dimensions of the upper and lower cover plates are both 110mm×110mm×4.5mm. Prepare two middle frames. The outer contour dimensions of the two middle frames are both 110mm×110mm, the inner frame dimensions are both 75mm×75mm, and the thicknesses are 0.5mm and 1mm respectively. Fixing the ceramic plate mold: First, clean the mold surface using a steel brush; second, apply ethyl cyanoacrylate adhesive (502 glue), evenly applying the glue to the bonding surface of the middle frame with a thickness of 1mm; finally, assemble and fix the mold by aligning and fixing the lower cover plate and the glued middle frame. S3. Loosely fill the inner cavity of the intermediate frame with pure nickel powder with a particle size range of 45-75μm. Then clean the residual powder on the intermediate frame and attach a 0.5mm thick intermediate frame to the 1mm thick intermediate frame in the same manner. Next, loosely fill the inner cavity of the intermediate frame with pure nickel powder with a particle size range of 10-30μm. Then use a scraper to scrape off the excess pure nickel powder along the upper surface of the intermediate frame, so that the surface flatness error of the pure nickel powder is ≤0.1mm. During operation, the working surface of the scraper must be a continuous smooth plane to ensure the flatness of the powder layer. Then use a fine brush to remove the residual powder on the outer edge of the intermediate frame and the surface of the mold. Finally, accurately align the upper cover plate with the upper end face of the intermediate frame and complete the mold closing. When laying the second layer of powder, try to avoid pressing it with force to prevent the upper layer of powder from being embedded too much into the lower layer of coarse powder due to external force. After the mold is closed, the ceramic plate mold must always be kept in a horizontal translation state during the transfer process. Any form of shaking or tilting is strictly prohibited. S4. Evacuate the sintering furnace cavity to a negative pressure of ≤10Pa to remove residual gas and ensure vacuum level, inhibit material oxidation, and do not apply external pressure to the ceramic plate mold throughout the process to maintain the loose powder state. The sintering temperature is 1150℃ and the holding time is 2h. Under these sintering conditions, a gradient double-layer porous nickel plate can be constructed to meet the needs of different filtration scenarios. According to actual needs, gradient multilayer porous nickel plate materials with different thicknesses and porosities can also be designed. S5. After sintering, once the temperature inside the sintering furnace has decreased to room temperature, the sintered porous nickel plate is demolded from the mold to obtain the porous nickel plate material. Samples of this porous nickel plate material are taken, and scanning electron microscopy (SEM) is used to characterize the three-dimensional distribution of pores and the growth morphology of sintered necks between particles, evaluating the pore network topology. The surface SEM image is shown below. Figure 5 As shown.

[0037] from Figure 5 As can be seen, the upper layer of this material is constructed from relatively fine 10-30μm nickel powder particles, with a uniform pore network and a planar pore size ranging from 10-50μm. Quantitative image analysis revealed a planar porosity of 17.2%, with significantly enlarged and firmly bonded particle sintering necks forming a high-strength, dense skeleton, providing primary mechanical support for the overall structure. The lower layer consists of relatively coarse 45-75μm nickel powder particles, with more developed pores and a planar pore size range increasing to 20-80μm. Calculations show an increased planar porosity of 21.4%, indicating richer pore space and higher permeability. While the inter-particle sintering necks are well-developed, their growth is slightly more gradual than in the upper layer, allowing them to maintain a high porosity while still forming a stable bond with the upper layer.

[0038] This design creates a gradient structure of "dense and robust upper layer, porous and interconnected lower layer." The dense upper skeleton ensures high overall strength and dimensional stability, while the highly porous lower network provides excellent permeability, large specific surface area, and load-bearing capacity. This double-layer gradient porous nickel plate, through the synergistic design of gradient pore size and porosity between the upper and lower layers, achieves both coarse and fine filtration functions while ensuring a balance between structural stability and filtration flux. It exhibits significant application advantages in scenarios with stringent requirements for filtration precision and efficiency, such as industrial fluid purification and precision filtration.

[0039] Example 4 A method for preparing a porous nickel plate material, which differs from Example 1 in that it further improves the strength of the porous nickel plate, specifically including the following steps: S1. The spherical pure nickel powder prepared by gas atomization is sieved, and pure nickel powder with a particle size range of 30-45μm and a loose packing density of 4.68±0.05g / cm³ is selected. 3 Then it is mixed with 316 stainless steel powder, with the weight ratio of 316 stainless steel powder to pure nickel powder being 1:9, and then the mixed powder is dried. S2. Prepare a ceramic plate mold. The dimensions of the upper and lower cover plates are both 110mm×110mm×4.5mm. The outer contour of the middle frame is 110mm×110mm, the inner frame is 75mm×75mm, and the thickness is 0.2mm. Fixing the ceramic plate mold: First, clean the mold surface using a steel brush; second, apply ethyl cyanoacrylate adhesive (502 glue) evenly to the bonding surface of the middle frame; finally, assemble and fix the mold by aligning and fixing the lower cover plate and the glued middle frame. S3. The sieved pure nickel powder is loosely packed into the inner cavity of the middle frame. Then, the excess pure nickel powder is scraped off along the upper surface of the middle frame with a scraper to ensure that the surface flatness error of the pure nickel powder is ≤0.1mm. During operation, the working surface of the scraper must be a continuous smooth plane to ensure the flatness of the powder layer. Then, the residual powder on the outer edge of the middle frame and the surface of the mold is removed with a fine brush. Finally, the upper cover plate is precisely aligned with the upper end face of the middle frame and the mold is closed. During the transition process after the mold is closed, the ceramic plate mold must always be kept in a horizontal translation state and any form of shaking or tilting is strictly prohibited. S4. Evacuate the sintering furnace cavity to a negative pressure of ≤10Pa to remove residual gas, ensure vacuum, and inhibit material oxidation. Do not apply external pressure to the ceramic plate mold throughout the process, maintain the powder in a loose state, and sinter at 1150℃ for 2 hours. S5. After sintering, once the temperature inside the sintering furnace has decreased to room temperature, the sintered porous nickel plate is demolded from the mold to obtain the porous nickel plate material. Samples of this porous nickel plate material are taken, and scanning electron microscopy (SEM) is used to characterize the three-dimensional distribution of pores and the growth morphology of sintered necks between particles, evaluating the pore network topology. The surface SEM image is shown below. Figure 6 As shown.

[0040] from Figure 6 As can be seen, a well-developed and uniform three-dimensional through-pore network structure has formed inside the material. The pores are interconnected in space and have an open morphology. The planar pore size ranges from 30 to 120 μm, which is conducive to the formation of multi-scale mass transfer channels. Quantitative analysis shows that its planar porosity is as high as 25.6%, and while the surface is strengthened, a higher proportion of pore space is successfully retained, which is significantly improved compared to Example 1. Furthermore, the sintering necks between powder particles are significantly longer and coarser. More importantly, due to the addition of 316 stainless steel powder, a nickel-iron alloyed metallurgical bonding bridge is formed between nickel particles during sintering. The presence of this strengthening phase transforms the connection points between particles from simple physical contact to a strong metallurgical bond, thereby greatly improving the load-bearing capacity of the skeleton network, and its mechanical strength is significantly higher than that of Example 1.

[0041] Comparative Example 1 The traditional loose-pack sintering method was adopted, in which spherical pure nickel powder prepared by gas atomization was directly sintered in a loose pack, with a loose pack density of 4.37±0.05 g / cm³. 3A porous nickel plate material was produced. However, tests showed that this porous nickel plate material could not form good pore sizes, and its porosity was no higher than 8%, indicating a low porosity.

[0042] Comparative Example 2 The difference from Example 1 is that step S1 is omitted, and spherical pure nickel powder prepared by gas atomization is directly used with a ceramic plate mold; otherwise, it is the same as Example 1. This porous nickel plate material was measured to be unable to form a well-connected pore network, and its porosity is no higher than 13%, indicating a low porosity.

[0043] Comparative Example 3 The difference from Example 1 is that steps S2 and S3 are omitted; that is, a ceramic plate mold is not used, and the sieved pure nickel powder is directly sintered in a loose pack. The rest is the same as in Example 1. Because the atomized powder has good sphericity, it cannot maintain its shape and cannot be molded without the addition of a binder.

[0044] Data Analysis The experimental results of Examples 1 and 2 show that the porous nickel plate material prepared by the method of this application can possess both good strength and pore connectivity. When the product already possesses both good strength and pore connectivity, if a product is desired to have even greater strength, a powder with a smaller particle size can be selected; if a product is desired to meet greater fluid permeability requirements, a powder with a larger particle size can be selected.

[0045] The difference between Example 3 and Example 1 lies in the addition of an intermediate frame, resulting in a double-layer porous nickel plate. This double-layer porous nickel plate, through a gradient synergistic design of pore size and porosity between the upper and lower layers, achieves both coarse and fine filtration functions while ensuring a balance between structural stability and filtration flux. It exhibits significant application advantages in scenarios with stringent requirements for filtration accuracy and efficiency, such as industrial fluid purification and precision filtration. This fully demonstrates that the preparation method of this application can not only prepare porous nickel plate materials with adjustable single-layer thickness, but also, by stacking intermediate frames of different thicknesses, prepare integrally formed double-layer or multi-layer porous nickel plate materials with strong interfacial bonding. This high flexibility provides an advanced preparation method for porous materials with gradient functions.

[0046] The difference between Example 4 and Example 1 is the addition of 316 stainless steel powder. Compared to Example 1, this porous nickel plate material not only exhibits improved porosity but also significantly enhanced strength. This fully demonstrates that mixing 316 stainless steel powder with sieved pure nickel powder can further improve the strength and porosity of the porous nickel plate, and the target strength and porosity can be obtained by adjusting the amount added, thus meeting more diverse application scenarios.

[0047] The difference between Comparative Example 1 and Example 1 lies in the fact that the spherical nickel powder prepared by gas atomization is directly subjected to the traditional loose-pack sintering process. The resulting porous nickel plate material cannot form good pore size, and the porosity is significantly lower than that of Example 1. This indicates that compared with the existing loose-pack sintering method, the porous nickel plate prepared by the method of this application not only has good mechanical strength, but also forms a well-connected pore network, which enables the porous nickel plate material to achieve the effect of improving permeability in fields such as gas-liquid filtration and separation.

[0048] The difference between Comparative Example 2 and Example 1 is that the powder is not sieved, and the porosity of the resulting porous nickel plate material is lower than that of Example 1. This indicates that without sieving, a well-structured three-dimensional interconnected network cannot be obtained. Powder without sieving exhibits a disordered particle size distribution, with random mixing of coarse and fine particles leading to an imbalance in particle size distribution. During sintering, this easily results in dense packing and inter-particle filling effects, causing localized over-density in the sintered body. This not only makes it difficult to construct a uniform, interconnected three-dimensional interconnected network but also leads to a complete loss of control over the pore formation process (e.g., low porosity, disordered pore size distribution, and increased proportion of closed pores). Therefore, this application achieves precise control of porosity, pore size, and pore connectivity through precise sieving, while also reasonably reserving effective inter-particle space.

[0049] The difference between Comparative Example 3 and Example 1 is that no ceramic plate mold was used. Since no binder was added, it could not maintain its shape and therefore could not be molded.

[0050] In summary, the preparation method of this application constructs a three-dimensional interconnected pore network without the need for a pore-forming agent by screening powder particle size, controlling calcination temperature and time, and synergistic effect of mold structure. The resulting porous nickel plate material not only has good strength, but its permeability is also significantly better than the closed-pore structure of the traditional pressing-sintering process, enabling the porous nickel plate material to achieve the effect of improved permeation flux in fields such as gas-liquid filtration and separation.

[0051] The embodiments described in this specific implementation are preferred embodiments of this application and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A method for preparing a porous nickel plate material, characterized in that, Includes the following steps: S1. Sift pure nickel powder and dry it; S2. Fix the ceramic plate mold, the ceramic plate mold includes an upper cover plate, a lower cover plate and a middle frame, the middle frame is located between the upper cover plate and the lower cover plate, and is used to form a porous nickel plate; S3. Spread the sieved pure nickel powder loosely into the inner cavity of the middle frame and level it, then close the mold. S4. Loosely sinter the ceramic plate mold after it has been assembled. S5. After sintering, cool to room temperature, demold, and separate to obtain porous nickel plate material.

2. The method for preparing a porous nickel plate material according to claim 1, characterized in that, In S1, the pure nickel powder is atomized spherical powder or atomized quasi-spherical powder, with an oxygen content ≤0.1% and a particle size range of 10-100μm.

3. The method for preparing a porous nickel plate material according to claim 2, characterized in that, The pure nickel powder is sieved to obtain powders in multiple different particle size ranges, including 10-30μm, 30-45μm, 45-75μm and 75-100μm.

4. The method for preparing a porous nickel plate material according to claim 1, characterized in that, In step S1, the sieved pure nickel powder is mixed with 316 stainless steel powder.

5. The method for preparing a porous nickel plate material according to claim 1, characterized in that, In S2, the number of intermediate frames is ≥1.

6. The method for preparing a porous nickel plate material according to claim 1, characterized in that, In step S3, after the leveling operation, the surface flatness error of the nickel powder is ≤0.1mm.

7. The method for preparing a porous nickel plate material according to claim 1, characterized in that, In S4, the vacuum degree during sintering is ≤10Pa, the temperature is 1100-1300℃, and the time is 1-2h.

8. A porous nickel plate material prepared by the method of any one of claims 1-7.

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