Gradient porous metal material, and preparation method and application thereof

Abstract

The application discloses a kind of gradient porous metal materials and its preparation method and application.The preparation method of the gradient porous metal material of the application includes the following steps: 1) a plurality of different particle size ranges of stainless steel powder is mixed, to obtain mixed powder;2) total printing layer is divided into a plurality of range layers, then laser selective melting is carried out on the surface of substrate using mixed powder, and laser power, scanning speed and scanning angle are controlled to gradually change along the printing direction one by one range layer, then stress relief annealing is carried out, to obtain gradient porous metal material.The gradient porous metal material of the application has high mechanical properties and high liquid absorption capacity, and its porosity and surface microstructure can be flexibly designed according to different application scenarios, suitable for self-lubricating, seawater desalination, pollution prevention and other fields, and its preparation method is simple to operate, raw materials are cheap and easy to obtain, production cycle is short, safe and environmentally friendly, suitable for large-scale industrial production.

Description

Technical Field

[0001] This invention belongs to the field of additive manufacturing technology, specifically relating to a gradient porous metal material, its preparation method, and its application. Background Technology

[0002] Porous metallic materials (such as foamed copper, porous aluminum alloys, and sponge titanium) have a large number of directional or random pores diffusely distributed inside, exhibiting good adsorption properties for gases and liquids. They have great application potential in seawater desalination, pollution control, and self-lubrication.

[0003] Currently, the template method is mainly used to prepare porous metal materials. However, this method has several drawbacks, including: 1) the need to design and manufacture templates, resulting in high costs; 2) the demolding process involves a series of chemical and physical changes, requiring specific reactants and equipment, making the procedure complex; 3) the yield of porous metal materials is low; and 4) the presence of reaction residues, which can easily cause environmental pollution. In recent years, researchers have applied 3D printing technology to the preparation of porous metal materials, primarily using 3D printing to design porous structures, followed by post-processing. However, 3D printing requires the pre-design of complex porous models, and the forming accuracy is limited by the machine. While post-processing can improve porosity, the procedure is complex, and these methods offer limited utilization and control of natural pores formed by various defects during the printing process. In summary, existing methods for preparing porous metal materials all have significant shortcomings and cannot fully meet the needs of practical applications.

[0004] Moreover, the capillary lift generated by the internal structure of porous metal materials prepared by existing methods is small. Although it can absorb liquid, when the structure is subjected to force (e.g., lifting and moving), some of the liquid stored inside will be thrown out due to inertia, which will lead to a decrease in the liquid storage capacity.

[0005] Furthermore, existing methods for preparing porous metal materials have the problem of balancing liquid absorption capacity and mechanical properties (for example, porous metal materials with high porosity have strong liquid absorption capacity but poor mechanical properties; porous metal materials with low porosity have good mechanical properties but poor liquid absorption capacity). Moreover, it is impossible to flexibly design the porosity of porous metal materials for various application scenarios, which seriously limits their application in self-lubrication, seawater desalination and other fields.

[0006] Therefore, it is of great significance to develop a simple, short-cycle, safe and environmentally friendly method for preparing porous metal materials, and to prepare porous metal materials with both high mechanical properties and high liquid absorption capacity. Summary of the Invention

[0007] The purpose of this invention is to provide a gradient porous metal material, its preparation method, and its application.

[0008] The technical solution adopted in this invention is: A method for preparing a gradient porous metallic material includes the following steps: 1) Mix stainless steel powders of different particle size ranges to obtain a mixed powder; 2) Divide the total printing layer into multiple range layers, then use mixed powder to perform laser selective melting on the substrate surface, and control the laser power, scanning speed and scanning angle to gradually change along the printing direction for each range layer, and then perform stress-relief annealing to obtain a gradient porous metal material.

[0009] Preferably, the mixed powder in step 1) is composed of stainless steel powder with a particle size of <150μm, stainless steel powder with a particle size of <48μm, and stainless steel powder with a particle size of <28μm in a mass ratio of 0.5~2:1:1~1.5.

[0010] Preferably, the substrate in step 2) is a stainless steel substrate.

[0011] Preferably, the substrate in step 2) is subjected to sandblasting treatment.

[0012] Preferably, the process parameters for laser selective melting in step 2) include: laser power of 60W to 180W, scanning speed of 800mm / s to 2000mm / s, and scanning spacing of 0.06mm to 0.12mm.

[0013] Preferably, in step 2), the laser power varies by 10W to 20W layer by layer along the printing direction.

[0014] Preferably, the scanning speed in step 2) varies from 200 mm / s to 400 mm / s layer by layer along the printing direction.

[0015] Preferably, the scanning angle in step 2) varies from 30° to 90° layer by layer along the printing direction.

[0016] Preferably, in step 2), the thickness of the mixed powder layer in a single range during the laser selective melting process is 10 mm to 30 mm.

[0017] Preferably, the printing direction in step 2) is unidirectional or bidirectional.

[0018] Preferably, the stress-relief annealing in step 2) is carried out at a temperature of 80℃ to 150℃ and the holding time is 6h to 12h.

[0019] Preferably, the porosity of the gradient porous metal material in step 2) is 3% to 50%, and the porosity varies layer by layer along the printing direction.

[0020] A gradient porous metallic material, which is prepared by the above-described method.

[0021] Preferably, the surface of the gradient porous metal material is further provided with an array of rough structures (without fixed morphology and size, designed according to different applications). In seawater desalination applications, designing this rough structure can increase the contact area between the porous structure surface and air, thereby increasing the evaporation rate of seawater; in electrosurgical applications (different from seawater desalination), designing this rough structure can increase the oil storage capacity of the porous structure, thereby effectively reducing tissue adhesion.

[0022] Preferably, the arrayed rough structures are formed by selective laser melting.

[0023] Application of a gradient porous metal material as described above in the fields of self-lubrication, seawater desalination, or pollution control.

[0024] The beneficial effects of the present invention are: the gradient porous metal material of the present invention has both high mechanical properties and high liquid absorption capacity, and its porosity and surface microstructure can be flexibly designed according to different application scenarios, making it suitable for self-lubrication, seawater desalination, pollution control and other fields. Moreover, its preparation method is simple to operate, the raw materials are cheap and readily available, the production cycle is short, and it is safe and environmentally friendly, making it suitable for large-scale industrial production.

[0025] Specifically: 1) This invention can control the distribution and numerical variation of porosity and pore size of printed parts along the printing direction by gradient design of printing parameters. It can form a porous structure with gradient changes in porosity and pore size inside porous metal materials, and does not require complicated pre / post-processing, thus shortening the production cycle. 2) By designing the printing parameters, this invention can print porous metal materials with different physical and chemical properties to meet the performance requirements of different application scenarios; 3) This invention can make full use of the various internal pores, cracks and other natural porous structures formed during the printing process due to factors such as partial melting of powder, spheroidization effect and surface cracks, without the need for additional design of complex porous structures; 4) This invention can design the surface microstructure of porous metal materials according to different application scenarios, thereby improving the actual performance of porous metal materials in specific application scenarios; 5) The gradient porous metal material of the present invention does not produce toxic or harmful substances during the printing process, making it safe and environmentally friendly. The stainless steel alloy powder used is inexpensive, and there is no raw material loss during the production process, saving production costs. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of the gradient porous metal material in Example 1.

[0027] Figure 2 This is a cross-sectional view of the range layer formed by printing under different laser powers in Example 1.

[0028] Figure 3 This is a schematic diagram of the electrosurgical unit in Example 1.

[0029] Figure 4 The images show the anti-adhesion effect test results of a conventional electrosurgical unit, a conventional pore electrosurgical unit, and the electrosurgical unit in Example 1.

[0030] Figure 5 This is a schematic diagram of the structure of the gradient porous metal material in Example 2.

[0031] Figure 6 This is a schematic diagram of the seawater desalination device in Example 2.

[0032] Figure 7 This is a schematic diagram of the hydrothermal power generation device in Example 3.

[0033] Explanation of reference numerals in the attached diagram: 10. Blade head; 11. Connecting part; 12. Blade handle; 20. Evaporation component; 21. Evaporation component support; 22. Seawater inlet; 23. Baffle plate; 24. Freshwater outlet; 25. Condensing plate support; 26. Condensing plate; 27. Transparent glass chamber; 30. Energy conversion component; 31. Thermoelectric generator; 32. Microchannel; 33. Condenser; 34. Water storage tank; 35. Valve; 36. Water pump; 37. Circulating water channel; 38. Electric fan; 39. Thermoelectric generator structure support. Detailed Implementation

[0034] The present invention will be further explained and described below with reference to specific embodiments.

[0035] Example 1: A gradient porous metallic material (structural schematic diagram as shown) Figure 1 As shown; the surface contains rough microstructures), its preparation method is as follows: 1) Add the 316 stainless steel powder sieved through a 100-mesh sieve, the 316 stainless steel powder sieved through a 300-mesh sieve, and the 316 stainless steel powder sieved through a 500-mesh sieve to a mixer in a mass ratio of 0.5:1:1 and mix evenly. Then place the mixture in an air atmosphere and let it stand at room temperature for 12 hours to obtain a mixed powder. 2) Divide the total printing layers into 5 range layers, and then use mixed powder to perform laser selective melting on the surface of a stainless steel substrate (which has undergone pretreatment, the operation of which is as follows: start the air compressor, adjust the pressure to 0.6MPa, then place the stainless steel substrate at an angle, then use a shot blasting machine to uniformly sandblast the surface of the stainless steel substrate, then blow away the floating dust and let it stand for 1 day). The laser power, scanning speed, and scanning angle are controlled to gradually increase along the printing direction for each range layer. The process parameters for laser selective melting are as follows: unidirectional printing, laser power of 60W~120W, laser power increasing by 15W for each range layer along the printing direction, scanning speed of 800mm / s~2000mm / s, scanning speed increasing by 15W for each range layer along the printing direction. The scanning speed is increased to 300 mm / s, the scanning interval is 0.06 mm, the scanning angle changes by 30° for each range layer along the printing direction, and the thickness of the mixed powder in each range layer along the printing direction is 15 mm. Then, it is placed in a constant temperature oven at 150°C for 6 hours (to eliminate residual stress). Then, it continues to be melted by laser selective melting. Using the processing parameters of the outermost range layer, a rough microstructure with a size of micrometer and arranged in an array is printed on the surface of the outermost range layer (gradient porous metal material substrate + surface rough microstructure, oil injection can effectively reduce tissue adhesion), resulting in a gradient porous metal material (porosity of 3% to 15%, and porosity changes for each range layer along the printing direction).

[0036] Performance testing: The internal structure of the extent layer printed at different laser powers (75W, 90W, and 105W) in this embodiment was tested using a high-resolution desktop Micro-CT scanner. The resulting cross-sectional slice images of the extent layer are shown below. Figure 2 As shown.

[0037] Depend on Figure 2 It can be seen that as the laser power increases, the porosity inside the zone layer decreases, indicating that the process parameters of laser selective melting have a significant control effect on the porosity of the zone layer.

[0038] An electrosurgical knife (structural diagram as shown) Figure 3 As shown), it consists of a blade head 10, a connecting part 11 and a handle 12. The blade head 10 is made of the gradient porous metal material in this embodiment (the handle is inserted into the electric knife handle for use, and the electric knife handle is connected to the high-frequency power supply through a wire; the blade head acts on human tissue through the thermal effect generated by the high-frequency current to achieve the purpose of cutting and hemostasis).

[0039] Performance testing: A conventional electrosurgical knife (with a blade made of a non-porous metal material), a conventional pore electrosurgical knife (with a blade made of a porous metal material with a single pore), and the electrosurgical knife in this embodiment were immersed in silicone oil with a viscosity of 200 mPa·s for 2 minutes, and then used to cut pork. The resulting anti-sticking effect test diagram is shown in the figure. Figure 4 (a is a conventional electrosurgical knife, b is a conventional pore electrosurgical knife, and c is the electrosurgical knife in this embodiment.)

[0040] Depend on Figure 4 It can be seen that the area of ​​the adhering material (black area) on the electrosurgical knife in this embodiment is the smallest. The reason is that the gradient porous metal material can use the difference in porosity of different range layers to generate capillary lift difference, which can continuously transport lubricating oil to the oil consumption part, forming a continuous oil film between the cutting part and the cutting head, thereby effectively reducing the adhesion of tissue on the surface of the electrosurgical knife and improving the stability of the tissue cut by the electrosurgical knife.

[0041] Example 2: A gradient porous metallic material (structural schematic diagram as shown) Figure 5 As shown; the surface contains a rough structure), its preparation method is as follows: 1) Add the 316 stainless steel powder sieved through a 100-mesh sieve, the 316 stainless steel powder sieved through a 300-mesh sieve, and the 316 stainless steel powder sieved through a 500-mesh sieve to a mixer in a mass ratio of 2:1:1 and mix evenly. Then place the mixture in an air atmosphere and let it stand at room temperature for 12 hours to obtain a mixed powder. 2) Divide the total printing layers into 10 range layers, and then use mixed powder to perform laser selective melting on the surface of a stainless steel substrate (which has undergone pretreatment, the operation of which is as follows: start the air compressor, adjust the pressure to 0.7MPa, then place the stainless steel substrate at an angle, then use a shot blasting machine to uniformly sandblast the surface of the stainless steel substrate, then blow away the floating dust and let it stand for 1 day). The laser power, scanning speed, and scanning angle are controlled to gradually change along the printing direction for each range layer. The process parameters for laser selective melting are as follows: bidirectional printing, laser power of 100W~180W, laser power increasing by 20W for each range layer along the printing direction, scanning speed of 800mm / s~2000mm / s, scanning... The scanning speed increases by 300 mm / s layer by layer along the printing direction, the scanning interval is 0.10 mm, the scanning angle changes by 60° layer by layer along the printing direction, and the thickness of the mixed powder in each layer along the printing direction is 10 mm. Then, it is placed in a constant temperature chamber at 100°C for 8 hours, and then laser selective melting is continued. Using the processing parameters of the outermost layer, a rough structure with a size in the millimeter range, pyramid shape, and array arrangement is printed on the surface of the outermost layer (to increase the evaporation area), resulting in a gradient porous metal material (porosity of 10% to 45%, and porosity changes layer by layer along the printing direction).

[0042] A seawater desalination device (structural schematic diagram shown) Figure 6As shown, it consists of an evaporation component 20, an evaporation component support 21, a seawater inlet 22, a baffle 23, a freshwater outlet 24, a condenser plate support 25, a condenser plate 26, and a transparent glass chamber 27. The evaporation component 20 is mounted on the evaporation component support 21 and is made of the gradient porous metal material in this embodiment. The condenser plate 26 is supported and fixed by the condenser plate support 25.

[0043] When the seawater desalination device in this embodiment is working, the evaporation component absorbs seawater through capillary lift, filling the entire evaporation component with seawater. Sunlight shines through the transparent glass chamber onto the upper surface of the evaporation component, which absorbs the sunlight and converts it into heat energy, causing the water on the surface of the evaporation component to evaporate. The resulting water vapor liquefies into liquid fresh water on the surface of the condenser plate. The liquid fresh water flows down the surface of the condenser plate and collects in the bottom fresh water collection area. The fresh water collection area is isolated from the seawater on one side by a partition, and the fresh water is discharged through the fresh water outlet on the other side.

[0044] In this embodiment, the evaporation component of the seawater desalination device is made of a gradient porous metal material. This material has porosity and pore size that vary along the height direction, and the variation pattern can be flexibly designed as needed. When water storage in the middle is required, the upper and lower parts of the evaporation component should be symmetrically distributed. When water storage in the upper part is required, the pore size and porosity should decrease continuously along the height direction. The large pores at the bottom can provide a larger flow rate, while the small pores at the top can provide a greater capillary lift than at the bottom, siphoning seawater from the lower surface of the evaporation component to the upper surface. The gradient porous metal material can also efficiently absorb sunlight and convert it into heat energy, achieving interface heating and significantly improving the efficiency of seawater evaporation. The gradient porosity design can optimize the balance between light absorption, water transport, and steam dissipation, while also achieving resistance to salt deposition.

[0045] Example 3: A gradient porous metallic material (with a rough surface structure) is prepared by the following method: 1) Add the 316 stainless steel powder sieved through a 100-mesh sieve, the 316 stainless steel powder sieved through a 300-mesh sieve, and the 316 stainless steel powder sieved through a 500-mesh sieve to a mixer in a mass ratio of 1.5:1:1.5 and mix evenly. Then place the mixture in an air atmosphere and let it stand at room temperature for 12 hours to obtain a mixed powder. 2) The total printing layers are divided into 10 range layers. Then, using mixed powder, laser selective melting is performed on the surface of a stainless steel substrate (pre-treated as follows: start the air compressor, adjust the pressure to 0.8MPa, then place the stainless steel substrate at an angle, then uniformly sandblast the surface with a shot blasting machine, blow away the dust, and let it stand for 1 day). The laser power, scanning speed, and scanning angle are controlled to gradually increase along the printing direction for each range layer. The laser selective melting process parameters are as follows: bidirectional printing, laser power 80W~160W, laser power increasing by 20W for each range layer along the printing direction, scanning speed 800mm / s~2000mm / s, scanning speed increasing by 300mm / s for each range layer along the printing direction. The scanning speed was m / s, the scanning interval was 0.08 mm, and the scanning angle changed by 45° for each range layer along the printing direction. The thickness of the mixed powder layer in each range layer along the printing direction was 10 mm, 20 mm, 30 mm, 20 mm and 10 mm respectively. Then it was placed in a constant temperature oven at 120°C for 6 hours. Then it was further processed by selective laser melting. Using the processing parameters of the outermost range layer, a rough structure with a size of millimeters, pyramid shape and array arrangement was printed on the surface of the outermost range layer (to increase the evaporation area. The faster the evaporation rate, the greater the temperature difference, which is beneficial to power generation). Gradient porous metal material (porosity of 20% to 35%, and porosity changing for each range layer along the printing direction) was obtained.

[0046] A hydrothermal power generation device (structural schematic diagram as shown) Figure 7As shown, it consists of an energy conversion component 30, a thermoelectric generator 31, a microchannel 32, a condenser 33, a water storage tank 34, a valve 35, a water pump 36, a circulating water channel 37, an electric fan 38, and a thermoelectric generator structure support 39. The energy conversion component 30 is made of the gradient porous metal material in this embodiment. It is located at the top of the hydrothermal power generation device and can efficiently absorb sunlight and convert it into heat energy to achieve interface heating and drive water evaporation. The evaporated water comes from the water guiding layer set below the energy conversion component 30, which conducts the water in the water tank below to the lower surface of the energy conversion component 30. Below the water guiding layer is the thermoelectric generator 31, and below that is the microchannel 32, through which circulating cooling water is introduced. The thermoelectric generator 31 utilizes the hot end (energy conversion component) 30) The temperature difference between the heat exchanger and the cold end (microchannel 32) generates electrical energy, which is then converted into wind energy by the electric fan 38; the energy conversion component 30, the water guiding layer, the thermoelectric generator 31, and the microchannel 32 together constitute the thermoelectric power generation structure, which is mounted on the thermoelectric power generation structure support 39; the circulating water channel 37 connects the microchannel 32, the condenser 33, the water storage tank 34, the valve 35, and the water pump 36 into a water circulation loop; the condenser 33 cools the water vapor flowing out of the microchannel 32, causing it to liquefy and be recovered; the water storage tank 34 stores circulating cooling water, providing a stable cold water source for the system; the valve 35 controls the on / off state and flow rate of the cooling water loop, realizing the adjustment of operating conditions; the water pump 36 drives the cooling water to circulate in the loop, providing a continuous cooling water flow for the microchannel 32.

[0047] In this embodiment, the energy conversion component of the hydrothermal power generation device is made of a gradient porous metal material. The gradient porous metal material stores water in the upper and middle parts. Along the height direction, the porosity and pore size are the largest at the bottom, and the porosity and pore size decrease gently and continuously in the middle and upper parts. Furthermore, through a special control method of scanning interval, a dense state of small pores is achieved in the upper and middle parts. An array of pyramid structures is designed at the top to increase the contact area between water and air. These measures can improve the evaporation efficiency of water, increase the temperature difference between the upper and lower surfaces of the energy conversion component, enable the heat-electricity-wind coupling system to operate at a higher power, and improve the greenhouse temperature control efficiency and air circulation efficiency.

[0048] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a gradient porous metallic material, characterized in that, Includes the following steps: 1) Mix stainless steel powders of different particle size ranges to obtain a mixed powder; 2) Divide the total printing layer into multiple range layers, then use mixed powder to perform laser selective melting on the substrate surface, and control the laser power, scanning speed and scanning angle to gradually change along the printing direction for each range layer, and then perform stress-relief annealing to obtain a gradient porous metal material.

2. The method for preparing gradient porous metallic materials according to claim 1, characterized in that: Step 1) The mixed powder is composed of stainless steel powder with a particle size of <150μm, stainless steel powder with a particle size of <48μm and stainless steel powder with a particle size of <28μm in a mass ratio of 0.5~2:1:1~1.

5.

3. The method for preparing gradient porous metallic materials according to claim 1, characterized in that: Step 2) The process parameters for laser selective melting include: laser power of 60W to 180W, scanning speed of 800mm / s to 2000mm / s, and scanning spacing of 0.06mm to 0.12mm.

4. The method for preparing gradient porous metallic materials according to claim 1 or 3, characterized in that: Step 2) The laser power changes by 10W to 20W layer by layer along the printing direction; Step 2) The scanning speed changes by 200mm / s to 400mm / s layer by layer along the printing direction; Step 2) The scanning angle changes by 30° to 90° layer by layer along the printing direction.

5. The method for preparing gradient porous metallic materials according to claim 1 or 3, characterized in that: Step 2) The thickness of the mixed powder layer in a single range during the laser selective melting process is 10mm to 30mm.

6. The method for preparing gradient porous metallic materials according to claim 1 or 3, characterized in that: Step 2) The printing direction can be unidirectional or bidirectional.

7. The method for preparing gradient porous metallic materials according to claim 1 or 3, characterized in that: Step 2) The stress-relief annealing is carried out at a temperature of 80℃~150℃ and a holding time of 6h~12h.

8. The gradient porous metallic material according to claim 1 or 3, characterized in that: Step 2) The porosity of the gradient porous metal material is 3% to 50%, and the porosity changes layer by layer along the printing direction.

9. A gradient porous metallic material, characterized in that, It is prepared by the preparation method described in any one of claims 1 to 8.

10. The application of a gradient porous metal material as described in claim 9 in the fields of self-lubrication, seawater desalination, or pollution control.

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