Pulsating heat pipe radiator with gradient porous material and manufacturing method of pulsating heat pipe radiator

Abstract

According to the pulsating heat pipe radiator with the gradient porous material and the manufacturing method of the pulsating heat pipe radiator, the gradient porous material is wrapped by an evaporation cavity wall and comprises a first porous part and a second porous part, and a first porous object and a second porous object are arranged at intervals and are different in pore diameter; the pipeline is composed of one or more capillary tubes, each capillary tube comprises a first end, a second end and a condensation section, the first end is communicated with the first porous part, the second end is communicated with the second porous part, and the condensation section is embedded into the cooling groove. The driving force and resistance difference of different areas of the gradient porous material is utilized, so that an obvious gas-liquid separation channel is generated in the gradient porous material, and a capillary tube is promoted to form a one-way flow trend; according to the manufacturing method, gradient porous materials are customized through the additive manufacturing technology, randomness in the machining process is avoided, aperture regulation and control of different areas are achieved, and the heat transfer efficiency of the pulsating heat pipe is improved. The heat dissipation device is particularly suitable for heat dissipation of electronic devices under high heat flux density.

Description

Technical Field

[0001] This invention relates to the field of pulsating heat pipe technology, and in particular to a pulsating heat pipe radiator with a gradient porous material and its manufacturing method. Background Technology

[0002] Due to the rapid development of new communication and information technologies, electronic devices are becoming increasingly miniaturized. Consequently, various semiconductor devices are employing high-density integration technology, leading to a sharp increase in heat flux density during operation. Heat accumulation within a limited space can significantly reduce the performance and lifespan of electronic devices, and also cause unnecessary energy loss between system circuits. Therefore, devising a rational and efficient heat dissipation method has become a serious challenge in the fields of electronics and communications.

[0003] As a highly efficient two-phase passive thermal management technology, pulsating heat pipes have broad application potential in the field of heat dissipation for electronic devices due to their advantages such as simple structure, low manufacturing cost and good design flexibility.

[0004] A pulsating heat pipe is typically formed by bending a capillary tube and can be divided into three parts: an evaporation section, a condensation section, and an adiabatic section. The evaporation section absorbs heat from the heat source, and a small portion of the input heat is converted into the kinetic energy of the self-oscillating flow of the working fluid in the pulsating heat pipe. The vast majority of the remaining heat is transferred to the condensation section through the latent heat generated by the phase change of the working fluid and the sensible heat of the liquid plug. The condensation section is then cooled by the heat sink, achieving efficient heat transfer.

[0005] Although pulsating heat pipes have high heat transfer efficiency, they still have some key technical problems in practical applications: the temperature uniformity and stability of the evaporation section of the pulsating heat pipe are poor, and there may be large thermal overshoot and excessive regional temperature difference during operation, which leads to a decrease in the performance of heat dissipation equipment and limits the practical application of pulsating heat pipes.

[0006] Patent CN102829660A discloses a pulsating heat pipe heat exchanger based on foam material. This patent uses a cavity containing metal foam to replace the elbows of traditional pulsating heat pipes, and the cavities of the evaporation and condensation sections are connected by multiple parallel pipes. In this type of heat exchanger, there is a conflict in the flow direction between liquid returning to the evaporator and gas flowing to the condenser, which affects the heat exchange efficiency to some extent. Furthermore, although adding metal foam to the condensation section increases the heat exchange area, the complex and tortuous metal skeleton hinders the liquid return to the evaporation section, greatly increasing the flow resistance. While metal foam significantly enhances the boiling heat transfer in the evaporation section, it also increases the relative flow resistance between gas and liquid, hindering gas escape and liquid return in the evaporation section, thus reducing the heat transfer efficiency of the heat exchanger. In addition, the structure of metal foam is usually irregular, and its pore distribution and shape do not have strict periodicity and symmetry, making it difficult to deterministically control its structure. This leads to a certain degree of randomness in the manufacturing process, making it impossible to achieve adjustable functional design, and often resulting in large regional temperature differences. Summary of the Invention

[0007] The purpose of this invention is to provide a pulsating heat pipe radiator with a gradient porous material.

[0008] To achieve the above-mentioned objectives, the present invention provides the following technical solution.

[0009] A pulsating heat pipe radiator with gradient porous material includes a cooling tank, a gradient porous material, an evaporation chamber wall, and pipes. The gradient porous material is wrapped by the evaporation chamber wall and includes a first porous portion and a second porous portion, which are spaced apart. The pore size of the first porous portion is smaller than that of the second porous portion. The pipes are composed of a single capillary or multiple capillary tubes. Each capillary tube includes a first end, a second end, a condensation section, a first pipe segment, and a second pipe segment. The first end is the port of the first pipe segment, and the second end is the port of the second pipe segment. The condensation section is located between the first pipe segment and the second pipe segment. The first end communicates with the first porous portion, and the second end communicates with the second porous portion. The condensation section is embedded in the cooling tank. The pulsating heat pipe radiator with gradient porous material is filled with a working fluid. In this way, gradient porous materials are used in the evaporation section to enhance boiling heat transfer. The gradient pore size causes the flow characteristics such as permeability and water absorption capacity of the porous material, as well as the heat transfer characteristics such as heat transfer area and nucleation sites, to also exhibit gradient changes. The differences in driving force and resistance in different regions create different flow trends in adjacent pipes, prompting the radiator to generate a more obvious gas-liquid separation channel. This reduces the gas escape resistance and liquid backflow resistance during the phase change process of the porous material, promotes unidirectional circulation flow in the capillary, improves the efficient and stable heat transfer of the pulsating heat pipe radiator, and has a lower surface temperature difference.

[0010] Furthermore, the evaporation chamber wall is flat, and one or more sides of the evaporation chamber wall can be attached to the electronic components to be cooled. An interface thermally conductive material is provided between the electronic components and the evaporation chamber wall. The contact between the evaporation chamber wall and the electronic components allows the heat from the electronic components to be directly transferred to the evaporation chamber wall, thereby reducing the temperature of the electronic components. Furthermore, the use of the interface thermally conductive material eliminates gaps between the evaporation chamber wall of the pulsating heat pipe radiator and the electronic components, reducing thermal resistance.

[0011] Furthermore, the evaporation chamber wall includes a first heat dissipation surface, a second heat dissipation surface, and a peripheral wall. The first heat dissipation surface and the second heat dissipation surface are separated from the evaporation chamber. The peripheral wall is provided with a liquid filling hole, which is controlled by a valve to open and close. This facilitates heat dissipation for electronic components that need to be stacked.

[0012] Furthermore, the evaporation chamber wall is made of a metallic material, and the first porous portion and the second porous portion are made of the same metallic material. This reduces the thermal resistance of the evaporation chamber wall, and using the same metallic material for the first porous portion and the second porous portion facilitates the processing and manufacturing of gradient porous materials.

[0013] Furthermore, the cooling tank is provided with a cooling fluid inlet and a cooling fluid outlet, and the capillary tube is U-shaped.

[0014] Furthermore, the working fluid exhibits an alternating gas-liquid two-phase distribution within the capillary and the gradient porous material.

[0015] Furthermore, the first porous portion is composed of unit cells, and the second porous portion is composed of unit cells, wherein the pore size of the unit cells constituting the first porous portion is smaller than the pore size of the unit cells constituting the second porous portion.

[0016] Furthermore, the pore size D of the unit cell constituting the first porous portion h (m), the pore size D of the unit cell constituting the second porous portion l (m) and capillary diameter D p (m) satisfies the following formula:

[0017]

[0018] Where, ρ l (kg / m 3 ρ represents the density of the liquid working fluid inside the pulsating heat pipe radiator. v (kg / m 3 ) represents the density of the gaseous working fluid, and σ (N / m) represents the surface tension of the working fluid.

[0019] Another object of the present invention is to provide a method for manufacturing a heat sink.

[0020] A method for manufacturing a heat sink, characterized in that the pulsating heat pipe heat sink with gradient porous material described above comprises the following steps:

[0021] S1: The gradient porous material is printed using additive manufacturing technology;

[0022] S2: After printing, the gradient porous material is processed.

[0023] S3: The evaporation chamber wall is machined by cutting.

[0024] S4: Weld the gradient porous material to the evaporation chamber wall;

[0025] S5: Weld the pipeline, evaporator cavity wall, and cooling tank;

[0026] S6: Inject a small amount of working fluid into the pulsating heat pipe radiator with gradient porous material through the filling holes set in the evaporation chamber wall to clean the internal pipes and check for leaks;

[0027] S7: High-pressure nitrogen is introduced to purge the remaining working fluid from the pulsating heat pipe and to create a vacuum inside;

[0028] S8: After vacuuming, inject a certain amount of working fluid according to the filling rate and then seal the container.

[0029] The manufacturing method of this invention uses additive manufacturing technology to customize gradient porous materials, avoiding randomness in the processing, and realizing the control of pore size in different regions of the gradient porous material, thereby effectively enhancing the control of heat transfer efficiency of the pulsating heat pipe.

[0030] Furthermore, during the printing process in step S1, the protective gas inside the molding chamber is argon; the processing of the gradient porous material in step S2 specifically includes the following steps:

[0031] S21: The gradient porous material is annealed in a vacuum heat treatment furnace and held in the furnace at 800°C for 2 hours, and then naturally cooled in the furnace to eliminate residual stress.

[0032] S22: After heat treatment, the printed gradient porous material is separated from the substrate by low-speed wire cutting.

[0033] S23. The gradient porous material is sandblasted, and then the unmelted powder particles remaining in the pores are removed by high-pressure airflow.

[0034] S24. After removing the residual powder particles inside, perform ultrasonic cleaning on the gradient porous material.

[0035] S25. The gradient porous material is subjected to surface oxidation treatment and dried to obtain the final porous material sample. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of an embodiment of the pulsating heat pipe radiator with gradient porous material according to the present invention;

[0037] Figure 2 yes Figure 1 A cross-sectional view AA of an embodiment of a pulsating heat pipe radiator with gradient porous material is shown.

[0038] Figure 3 yes Figure 1 A schematic diagram of the gradient porous material in an embodiment of a pulsating heat pipe radiator with gradient porous material is shown.

[0039] Figure 4 yes Figure 1 A schematic diagram of a single capillary tube in the piping of an embodiment of a pulsating heat pipe radiator with gradient porous material is shown.

[0040] Figure 5 This is a flowchart of a method for manufacturing a heat sink with gradient porous materials. Detailed Implementation

[0041] Figure 1 The diagram illustrates a pulsating heat pipe radiator with a gradient porous material, including a gradient porous material 1, an evaporation chamber wall 2, a cooling tank 5, a pipe 4, and a liquid filling hole 3.

[0042] The cooling tank 5 includes a cooling fluid inlet 51 and a cooling fluid outlet 52.

[0043] The evaporation chamber is formed by the evaporation chamber wall 2. The gradient porous material 1 is located within the evaporation chamber and is enclosed by the evaporation chamber wall 2. For example... Figure 2 As shown, the evaporation chamber wall 2 can be flat. One or more sides of the evaporation chamber wall 2 can be attached to electronic components with heat dissipation capabilities. Specifically, the evaporation chamber wall includes a first heat dissipation surface, a second heat dissipation surface, and a peripheral wall. The first heat dissipation surface and the second heat dissipation surface are separated from the evaporation chamber, and the first and second heat dissipation surfaces can be attached to the electronic components. A liquid filling hole 3 is provided on the peripheral wall. The liquid filling hole 3 can be opened and closed by a valve.

[0044] The evaporation chamber wall 2 is made of a metallic material, such as aluminum alloy. Generally speaking, metallic materials have good thermal conductivity, which results in a lower thermal resistance for the evaporation chamber wall.

[0045] like Figure 3 As shown, the gradient porous material 1 includes a first porous portion 11 and a second porous portion 12, which are arranged at intervals. The pore size of the first porous portion 11 is smaller than that of the second porous portion 12.

[0046] Pipeline 4 consists of a single capillary or multiple capillary tubes. Figure 1 The illustrated embodiment shows a case where the conduit consists of multiple capillary tubes forming multiple pathways. In another embodiment, when the heat dissipation requirement is low, a single capillary tube forming one pathway is sufficient to meet the heat dissipation needs, or the conduit can be directly composed of a single capillary tube.

[0047] like Figure 4 As shown, the capillary tube includes a first end 41, a second end 42, a condensing section 43, a first pipe section 44, and a second pipe section 45. The first end 41 is the port of the first pipe section 44, and the second end 42 is the port of the second pipe section 45. The condensing section 43 is located between the first pipe section 44 and the second pipe section 45. The first end 41 is connected to the first porous portion 11 (meaning that fluid in the first pipe section can enter the first porous portion through the first end), and the second end 42 is connected to the second porous portion 12 (meaning that fluid in the second porous portion can enter the second pipe section through the second end). The condensing section 43 is embedded in the cooling tank 5. The first pipe section 44 and the second pipe section 45 can be bent according to the assembly environment, making them suitable for various assembly environments and providing great flexibility. The first pipe section 44 and the second pipe section 45 can be insulated.

[0048] The first porous portion 11 and the second porous portion 12 can be made of the same metal material, such as aluminum alloy.

[0049] The first porous portion 11 can be composed of unit cells, and the second porous portion 12 can be composed of unit cells. The pore size of the unit cells constituting the first porous portion 11 is smaller than the pore size of the unit cells constituting the second porous portion 12. The evaporation chamber wall 2 and the gradient porous material 1 can be fixed by means of welding or other methods.

[0050] The pore size D of the unit cell constituting the first porous portion 11 h (m), the pore size D of the unit cell constituting the second porous portion 12 l (m) and the capillary diameter D constituting pipe 4 p (m) satisfies the following formula:

[0051]

[0052] Where, ρ l (kg / m 3 ρ represents the density of the liquid working fluid inside a pulsating heat pipe radiator with gradient porous material. v (kg / m 3 ) represents the density of the gaseous working fluid, and σ (N / m) represents the surface tension of the working fluid.

[0053] The working fluid in a pulsating heat pipe radiator with gradient porous material can be water, methanol, ethanol, refrigerant R1336mzz(Z), and various self-wetting fluids. The working fluid can be injected into the pulsating heat pipe radiator with gradient porous material through the filling hole 3. The filling rate of the working fluid is controlled between 10% and 70%.

[0054] The working fluid exhibits an alternating gas-liquid two-phase distribution within the capillary and gradient porous material.

[0055] The cell shapes of the first porous portion 11 and the second porous portion 12 are not limited to those shown in the figure. They can also be various types of cells such as Kelvin cells, Weaire-Phelan cells, simple cubic cells, body-centered cubic cells, face-centered cubic cells, and TPMS (triple-period minimal surface) cells. The cell constituting the first porous portion 11 and the cell constituting the second porous portion 12 can be of the same type or different types.

[0056] Include Figure 1 The illustrated electronic device features a pulsating heat pipe radiator with a gradient porous material. The electronic device is attached to the evaporation chamber wall 2, and an interfacial thermally conductive material is placed between the electronic device and the evaporation chamber wall 2. The thermally conductive material can be thermally conductive silicone grease, indium, etc. This serves two purposes: firstly, it eliminates air between the electronic device and the evaporation chamber wall 2, reducing thermal resistance; secondly, it improves the uniformity of the surface temperature of the electronic device, preventing the formation of localized hot spots.

[0057] The evaporation chamber wall 2 is bonded to the electronic device requiring heat dissipation via a high thermal conductivity interface material such as indium, allowing heat transfer from the electronic device to the evaporation chamber wall 2 of the pulsating heat pipe radiator with a gradient porous material. The working fluid within the pulsating heat pipe radiator with the gradient porous material absorbs heat and undergoes a phase change. During this phase change, the first porous section 11 has a smaller pore size and stronger capillary absorption capacity, causing the liquid working fluid in the evaporation chamber to tend to move towards the location of the first porous section 11, and promoting the movement of the gaseous working fluid generated by the phase change towards the location of the second porous section 12. This results in a relatively larger proportion of liquid phase in the first porous section 11 and a relatively larger proportion of gaseous phase in the second porous section 12. Consequently, the pressure difference between the location of the second porous section 12 and the condensation section increases, and the movement resistance is relatively small, causing the gaseous working fluid to move from the location of the second porous section 12 towards the condensation section 43. The working fluid in the condensation section 43 is cooled by the cooling water in the cooling tank, undergoing phase change condensation. Meanwhile, the internal movement resistance at the location of the first porous section 11 is relatively large, making it difficult for the working fluid to move from the location of the second porous section 12 to the condensation section. However, under the influence of gravity in the other pipe, the liquefied working fluid in the condensation section 43 will move from the condensation section to the location of the first porous section 11. The difference in driving force and resistance between the first porous section 11 and the second porous section 12 promotes the formation of a more obvious gas-liquid separation channel within the gradient porous material. This reduces the resistance to gas escape and the resistance to liquid return in the condensation section within the gradient porous material 1, thereby forming a unidirectional flow trend within the capillary 4. This contributes to the efficient and stable heat transfer of the pulsating heat pipe radiator with gradient porous material.

[0058] In this embodiment, gradient porous materials are a class of materials whose pore structure, composition or properties gradually change along the spatial direction. Their porosity, pore size, material composition or topology can be designed in a specific gradient so that different regions exhibit different physical, mechanical or thermal properties.

[0059] This embodiment fully utilizes the characteristics of gradient porous materials, such as gradient thermal conductivity, optimized capillary transport, enhanced mechanical stability, and lightweight design, to embed porous materials into a phase change heat transfer system, thereby improving the overall heat transfer performance of the radiator in this embodiment.

[0060] In the appendix Figure 1 The model shown is used for simulation calculations.

[0061] The initial calculation parameters were set as follows: the overall dimensions of the gradient porous material were 185mm × 40mm × 5mm; the unit cells of the first porous portion 11 and the second porous portion 12 were both Kelvin units; the pore size of the first porous portion 11 was 2.5mm; the pore size of the second porous portion 12 was 5mm; the evaporation chamber wall 2 and the materials of the first porous portion 11 and the second porous portion 12 were all aluminum alloy. The working fluid was R1336mzz(Z), with a filling rate of 50%. The inner diameter of the capillary was 2mm, and the outer diameter was 3mm. The coolant in the cooling tank was water, with a flow rate of 5L / min and an inlet temperature of 20℃.

[0062] Simulation results show that when the heat flux density is 5.8 W / cm², the thermal resistance of this embodiment is 0.59 K / W. The temperature of the heated surface in this embodiment is relatively uniform, and the maximum temperature difference between different regions of the evaporation chamber wall does not exceed 5°C at the same time. In contrast, the thermal resistance of a traditional pulsating heat pipe with similar dimensions is 0.9 K / W, and the maximum temperature difference in the evaporation chamber is as high as 20°C. Therefore, the technical solution of this invention has superior heat transfer performance.

[0063] Figure 5 The method for manufacturing a pulsating heat pipe radiator with a gradient porous material is illustrated, including the following steps:

[0064] S1: Using additive manufacturing technology to print gradient porous materials into shapes;

[0065] S2: After printing, the gradient porous material is processed.

[0066] S3: Perform cutting and machining on the evaporation chamber wall;

[0067] S4: Weld the gradient porous material to the evaporation chamber wall;

[0068] S5: Weld the capillary tube, evaporator chamber wall, and cooling tank;

[0069] S6: Inject a small amount of working fluid into the pulsating heat pipe radiator with gradient porous material through the filling holes set in the evaporation chamber wall to clean the internal pipes and check for leaks;

[0070] S7: Inject high-pressure nitrogen to purge the remaining working fluid from the radiator and evacuate the interior to a vacuum.

[0071] S8: After vacuuming, inject a certain amount of working fluid according to the filling rate and then seal the container.

[0072] In step S1, during the printing process, the protective gas inside the forming chamber is argon; the processing of the gradient porous material in step S2 specifically includes the following steps:

[0073] S21: The gradient porous material is annealed in a vacuum heat treatment furnace and held in the furnace at 800°C for 2 hours, and then naturally cooled in the furnace to eliminate residual stress.

[0074] S22: After heat treatment, the printed gradient porous material is separated from the substrate by low-speed wire cutting.

[0075] S23. The gradient porous material is sandblasted, and then the unmelted powder particles remaining in the pores are removed by high-pressure airflow.

[0076] S24. After removing the residual powder particles inside, perform ultrasonic cleaning on the gradient porous material.

[0077] S25. The gradient porous material is subjected to surface oxidation treatment and dried to obtain the final porous material sample.

[0078] This method for manufacturing pulsating heat pipe radiators with gradient porous materials uses additive manufacturing technology to customize the gradient porous materials, avoiding randomness in the processing and enabling control over the pore size of different regions of the gradient porous materials. This effectively enhances the control over the heat transfer efficiency of the pulsating heat pipe. At the same time, by combining additive manufacturing technology with traditional processing technology, manufacturing efficiency is improved and manufacturing costs are reduced.

Claims

1. A pulsating heat pipe radiator with a gradient porous material, characterized in that, The device includes a cooling tank, a gradient porous material, an evaporation chamber wall, and piping. The gradient porous material is wrapped by the evaporation chamber wall and includes a first porous portion and a second porous portion, which are spaced apart. The pore size of the first porous portion is smaller than that of the second porous portion. The piping consists of a single capillary or multiple capillary tubes. Each capillary tube includes a first end, a second end, a condensation section, a first pipe segment, and a second pipe segment. The first end is the port of the first pipe segment, and the second end is the port of the second pipe segment. The condensation section is located between the first pipe segment and the second pipe segment. The first end communicates with the first porous portion, and the second end communicates with the second porous portion. The condensation section is embedded in the cooling tank. The pulsating heat pipe radiator with gradient porous material is filled with working fluid.

2. The pulsating heat pipe radiator with gradient porous material according to claim 1, characterized in that, The evaporation chamber wall is flat in shape, and one or more sides of the evaporation chamber wall can be attached to the electronic components to be dissipated. An interface thermal conductive material is provided between the electronic components to be dissipated and the evaporation chamber wall.

3. The pulsating heat pipe radiator with gradient porous material according to claim 2, characterized in that, The evaporation chamber wall includes a first heat dissipation surface, a second heat dissipation surface, and a peripheral wall. The first heat dissipation surface and the second heat dissipation surface are separated by the evaporation chamber. The peripheral wall is provided with a liquid filling hole, which is controlled to open and close by a valve.

4. The pulsating heat pipe radiator with gradient porous material according to claim 1, characterized in that, The evaporation chamber wall is made of metal material, and the first porous part and the second porous part are made of the same metal material.

5. The pulsating heat pipe radiator with gradient porous material according to claim 1, characterized in that, The cooling tank is provided with a cooling fluid inlet and a cooling fluid outlet, and the capillary tube is U-shaped.

6. The pulsating heat pipe radiator with gradient porous material according to claim 1, characterized in that, The working fluid exhibits an alternating gas-liquid two-phase distribution within the capillary and the gradient porous material.

7. The pulsating heat pipe radiator with gradient porous material according to any one of claims 1-6, characterized in that, The first porous portion is composed of unit cells, and the second porous portion is composed of unit cells. The pore size of the unit cells constituting the first porous portion is smaller than the pore size of the unit cells constituting the second porous portion.

8. The pulsating heat pipe radiator with gradient porous material according to claim 7, characterized in that, The pore size D of the unit cell constituting the first porous portion h (m), the pore size D of the unit cell constituting the second porous portion l (m) and capillary diameter D p (m) satisfies the following formula: Where, ρ l (kg / m 3 ρ represents the density of the liquid working fluid inside the pulsating heat pipe radiator. v (kg / m 3 ) represents the density of the gaseous working fluid, and σ (N / m) represents the surface tension of the working fluid.

9. A method for manufacturing a radiator, characterized in that, The method for manufacturing a pulsating heat pipe radiator with a gradient porous material as described in any one of claims 2-8 comprises the following steps: S1: The gradient porous material is printed using additive manufacturing technology; S2: After printing, the gradient porous material is processed. S3: The evaporation chamber wall is machined by cutting. S4: Weld the gradient porous material to the evaporation chamber wall; S5: Weld the pipeline, evaporator cavity wall, and cooling tank; S6: Inject a small amount of working fluid into the pulsating heat pipe radiator with gradient porous material through the filling holes set in the evaporation chamber wall to clean the internal pipes and check for leaks; S7: High-pressure nitrogen is introduced to purge the remaining working fluid from the pulsating heat pipe and to create a vacuum inside; S8: After vacuuming, inject a certain amount of working fluid according to the filling rate and then seal the container.

10. The method for manufacturing a radiator according to claim 9, characterized in that, During the printing process in step S1, the protective gas inside the forming chamber is argon; the processing of the gradient porous material in step S2 specifically includes the following steps: S21: The gradient porous material is annealed in a vacuum heat treatment furnace and held in the furnace at 800°C for 2 hours, and then naturally cooled in the furnace to eliminate residual stress. S22: After heat treatment, the printed gradient porous material is separated from the substrate by low-speed wire cutting. S23. The gradient porous material is sandblasted, and then the unmelted powder particles remaining in the pores are removed by high-pressure airflow. S24. After removing the residual powder particles inside, perform ultrasonic cleaning on the gradient porous material. S25. The gradient porous material is subjected to surface oxidation treatment and dried to obtain the final porous material sample.

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