A grinding and polishing method for porous metal materials

Abstract

This invention discloses a grinding and polishing method for porous metal materials, comprising the following steps: taking sintered porous metal materials and sequentially performing coarse grinding, fine grinding, fine polishing, cleaning, and drying to obtain the processed porous metal material; wherein, the conditions for coarse grinding are: a loading force of 0.2-0.5 MPa, a grinding disc speed of 100-400 rpm, a spindle speed of 0-10 rpm, and a grinding time of 1-5 min; and then performing fine grinding with coarse and fine wet sandpaper sequentially; during fine grinding, the coarse wet sandpaper has a mesh size of 400-800 grit, and the grinding conditions are: a loading force of 0.1-0.3 MPa, a grinding disc speed of 500-800 rpm, a spindle speed of 10-30 rpm, and a grinding time of 5-15 min. This invention can effectively avoid excessive deformation and pore structure damage of porous metal materials, and achieve effective control of pore blockage on the processed surface.

Description

Technical Field

[0001] This invention relates to the field of porous metal material processing technology, and in particular to a grinding and polishing method for porous metal materials. Background Technology

[0002] Porous metallic materials are a special type of engineering material that combines functional and structural properties. They are made from metal / alloy powders, metal meshes, metal fibers, etc., through pressing and near-melting-point high-temperature sintering. Due to their combination of the electrical and thermal conductivity, high structural strength, high temperature resistance, and corrosion resistance of metals with the unique properties of porosity and large specific surface area, they are widely used in fluid purification, gas dust removal, gas fluidization, powder fluidization conveying, sweating cooling, enhanced heat transfer, noise reduction, flame retardancy, and explosion protection.

[0003] However, in actual industrial applications, certain problems have been found. Specifically, when machining porous metal materials, the surface is difficult to meet processing requirements, especially as the pore structure on the machined surface is easily blocked, affecting the material's permeability, reducing its performance, and even causing the machined part to fail. To address these issues, patents CN101134257A and CN105081353A both propose a method of first filling and solidifying the porous material before machining. Specifically, an easily removable material (such as paraffin wax) is heated to a liquid state and permeates into the pores of the porous metal to be processed. A phase change transforms the filler material from liquid to solid. The solidified porous metal is then machined into the desired shape and size. After machining, the filler material in the porous metal pores is transformed from solid to liquid or gas through a phase change and then cleaned away. However, due to the different processing properties of the filler material and the porous metal, some pores on the surface of the machined porous metal remain blocked, and some pores are deformed. Additionally, a small amount of filler material remains in the pores. Summary of the Invention

[0004] Based on the technical problems existing in the background technology, the present invention proposes a grinding and polishing method for porous metal materials. The present invention combines step-by-step grinding and polishing processes and selects appropriate process parameters, which can effectively avoid excessive deformation and pore structure damage of porous metal materials while ensuring the processing accuracy of materials, maintain the shape of porous metal materials, and achieve effective control of pore blockage on the processing surface, thus effectively ensuring the integrity and stability of the pore structure.

[0005] This invention proposes a grinding and polishing method for porous metal materials, comprising the following steps: taking sintered porous metal materials and sequentially performing coarse grinding, fine grinding, fine polishing, cleaning, and drying to obtain the processed porous metal materials;

[0006] The conditions for rough grinding are: a loading force of 0.2-0.5 MPa, a grinding disc speed of 100-400 rpm, a spindle speed of 0-10 rpm, and a grinding time of 1-5 min.

[0007] Use coarse wet sandpaper and then fine wet sandpaper for fine sanding in sequence;

[0008] For fine grinding, the grit of the coarse wet sandpaper is 400-800 grit, and the grinding conditions are: a loading force of 0.1-0.3MPa, a grinding disc speed of 500-800rpm, a spindle speed of 10-30rpm, and a grinding time of 5-15min.

[0009] For fine grinding, use 1000-5000 grit sandpaper and the following grinding conditions: a loading force of 0.05-0.15 MPa, a grinding disc speed of 500-1000 rpm, a spindle speed of 20-50 rpm, and a grinding time of 10-30 minutes.

[0010] The inventors discovered that sintered porous materials all suffer from re-sintering deformation. When porous metal materials are cut and processed into workpieces of specific shapes and sizes, the processed surfaces of the porous metal materials are subjected to external forces that cause the materials to deform, squeezing and sealing the pore structure. Furthermore, metal residues or other additive residues can also easily clog the pores, thereby reducing the permeability and other properties of the porous metal materials.

[0011] To address the aforementioned issues, the inventors, through numerous experiments, discovered that combining step-by-step grinding and polishing techniques yields better results than single-pass grinding or direct polishing. Furthermore, the inventors found that during coarse grinding, both excessive and insufficient loading force negatively impact the processing effect. Insufficient loading force results in the incomplete removal of the sintered deformation layer, while excessive loading force leads to an overly thick deformation layer from the coarse grinding process, making subsequent fine grinding and polishing difficult and causing pore blockage and deformation. Conversely, during fine grinding, insufficient loading force makes it difficult to remove the deformation layer from the coarse grinding process; excessive loading force creates a thick processing layer, making fine polishing difficult and easily leading to pore blockage and deformation. During fine polishing, insufficient loading force makes it difficult to create holes, while excessive loading force causes pitting and wing-like defects on the processed surface, and deforms the pore structure. Inappropriate selection of sandpaper grit and processing time for coarse grinding, fine grinding, and fine polishing can also lead to pore blockage and deformation.

[0012] Therefore, through numerous experiments, the inventors selected appropriate processing parameters for each step, ensuring that the surface condition after rough grinding was perfectly suited for fine grinding, and the surface condition after fine grinding was perfectly suited for fine polishing, resulting in a well-maintained surface. The various steps worked together to ensure high processing accuracy while effectively preventing excessive deformation and pore structure damage in porous metal materials, preserving the shape of the porous metal material, and effectively controlling pore blockage on the processed surface. This effectively ensured the integrity and stability of the pore structure, thereby maintaining the permeability and other properties of the porous metal material.

[0013] Preferably, during coarse grinding, the mesh size of the wet sandpaper is 80-250.

[0014] Preferably, during fine grinding, the mesh ratio of coarse to fine wet sandpaper is 1:2-5.

[0015] Preferably, the conditions for fine polishing are: a loading force of 0.2-0.35 MPa, a grinding disc speed of 500-1500 rpm, a spindle speed of 30-100 rpm, and a polishing time of 30-120 min.

[0016] Preferably, during fine polishing, the ratio of the grinding disc speed to the spindle speed is 10-25:1.

[0017] Preferably, for fine polishing, the polishing compound has a specification of W0.5-W3.5.

[0018] In the polishing paste mentioned above, W represents micrometers, and the numbers represent the particle size of the abrasive grains.

[0019] Preferably, during fine polishing, the polishing cloth is made of one of the following materials: velvet, wool, or velvet.

[0020] The above-mentioned rough grinding, fine grinding, and polishing are all carried out on automatic grinding and polishing equipment. The automatic grinding and polishing equipment can be the HMP-1AE type metallographic sample grinding and polishing machine, which is equipped with a grinding disc and a spindle. The porous metal material can be fixed on the automatic grinding and polishing equipment with a clamp. The clamp can be designed according to the specifications of the sample to be processed, without the need to cut the porous metal material. Alternatively, the porous metal material can be cut first to match the clamp of a fixed specification before processing.

[0021] Preferably, the cleaning is ultrasonic cleaning.

[0022] Ultrasonic cleaning can be performed using at least one of deionized water, alcohol, or acetone.

[0023] Preferably, the power density of ultrasonic cleaning is 0.3-0.8 W / cm². 2 The frequency is 40-80kHz and the temperature is 30-50℃.

[0024] Preferably, the drying is vacuum drying.

[0025] Preferably, the vacuum degree of vacuum drying is -5×10⁻⁵. -5 Pa ~ -1×10 -5 The temperature is 75-200℃ and the time is 30-120 minutes.

[0026] The method described in this invention is applicable to porous metal materials with micro- and nano-pore sizes.

[0027] Preferably, the average pore size of the porous metal material is ≤200μm.

[0028] Preferably, the porous metal material is one of aluminum, aluminum alloy, copper, copper alloy, stainless steel, intermetallic compound, titanium alloy, and magnesium alloy.

[0029] Beneficial effects:

[0030] This invention combines step-by-step grinding and polishing processes, and selects appropriate process parameters. This can effectively avoid excessive deformation and damage to the pore structure of porous metal materials while ensuring the processing accuracy of the materials. It maintains the shape of the porous metal materials, effectively controls the pore blockage on the processing surface, and effectively ensures the integrity and stability of the pore structure, thereby maintaining the permeability and other properties of the porous metal materials. Moreover, this invention is simple to operate, highly automated, and low in cost. Attached Figure Description

[0031] Figure 1 The image shows the OM morphology of the polished surface of the porous brass in Example 1, where a is magnified 50 times and b is magnified 100 times.

[0032] Figure 2 The image shows the OM morphology of the polished surface of the porous brass in Example 2, where a is magnified 50 times and b is magnified 100 times.

[0033] Figure 3 The image shows the OM morphology of the polished surface of the porous tin bronze in Example 3, where a is magnified 50 times and b is magnified 100 times.

[0034] Figure 4 This is a magnified OM (omnidirectional surface) image of the polished surface of the porous brass in Comparative Example 1, magnified 100 times.

[0035] Figure 5 This is a magnified OM (morphological structure) image of the polished surface of the porous brass in Comparative Example 3, magnified 100 times.

[0036] Figure 6 This is a magnified OM (omnidirectional surface) image of the polished surface of the porous brass in Comparative Example 5, magnified 100 times.

[0037] Figure 7This is a magnified OM (morphological image) of the polished surface of the porous brass in Comparative Example 7, magnified 100 times.

[0038] Figure 8 This is a magnified OM (morphological image) of the polished surface of the porous brass in Comparative Example 9, magnified 100 times.

[0039] Figure 9 This is a magnified OM (omnidirectional surface) image of the polished surface of the porous brass in Comparative Example 11, magnified 100 times.

[0040] Figure 10 This is a magnified OM (omnidirectional surface) image of the polished surface of the porous brass in Comparative Example 13, magnified 100 times.

[0041] Figure 11 This is a magnified OM (morphological image) of the polished surface of the porous brass in Comparative Example 15, magnified 100 times. Detailed Implementation

[0042] The technical solution of the present invention will now be described in detail through specific embodiments.

[0043] Example 1

[0044] A method for polishing porous brass material includes the following steps: sintered porous brass material (with an average pore size of 20 μm) is placed on an HMP-1AE type automatic polishing equipment and fixed with a clamp; the surface to be processed is rough-ground and leveled using 180-grit wet sandpaper; the rough-ground conditions are: a loading force of 0.2 MPa, a grinding disc speed of 200 rpm, a spindle speed of 0 rpm, and a polishing time of 2.5 min;

[0045] Then, use coarse and fine wet sandpaper to finely grind the surface after coarse grinding until the scratches on the surface are shallow and in the same direction.

[0046] The coarse wet sandpaper has a mesh size of 800. The sanding conditions are: a loading force of 0.2 MPa, a grinding disc speed of 550 rpm, a spindle speed of 20 rpm, and a sanding time of 10 min.

[0047] The fine wet sandpaper has a mesh size of 2000. The sanding conditions are: a loading force of 0.15MPa, a grinding disc speed of 800rpm, a spindle speed of 35rpm, and a sanding time of 12min.

[0048] Then, apply polishing compound of specification W2.5 evenly to the woolen polishing cloth and perform fine polishing on the processed surface. The conditions for fine polishing are: loading force of 0.25MPa, grinding disc speed of 1000rpm, spindle speed of 75rpm, and polishing time of 30min.

[0049] Then, ultrasonic cleaning was performed sequentially with deionized water and ethanol, with the same ultrasonic cleaning parameters for each step: a power density of 0.3 W / cm³. 2 The frequency was 40kHz and the temperature was 35℃; the processed porous brass material was then obtained by vacuum drying, with a vacuum degree of -1×10⁻¹⁰. -5 Pa, temperature 80℃, time 30min.

[0050] Example 2

[0051] A method for polishing porous brass material includes the following steps: sintered porous brass material (with an average pore size of 5 μm) is placed on an HMP-1AE type automatic polishing equipment and fixed with a clamp; the surface to be processed is rough-ground and leveled using 180-grit wet sandpaper; the rough-ground conditions are: a loading force of 0.25 MPa, a grinding disc speed of 150 rpm, a spindle speed of 0 rpm, and a polishing time of 3 min;

[0052] Then, use coarse and fine wet sandpaper to finely grind the surface after coarse grinding until the scratches on the surface are shallow and in the same direction.

[0053] The coarse wet sandpaper has a mesh size of 500. The sanding conditions are: a loading force of 0.15MPa, a grinding disc speed of 500rpm, a spindle speed of 15rpm, and a sanding time of 8min.

[0054] The fine sandpaper has a mesh size of 1200. The sanding conditions are: a loading force of 0.1 MPa, a grinding disc speed of 800 rpm, a spindle speed of 25 rpm, and a sanding time of 15 min.

[0055] Then, apply polishing paste of specification W1.5 evenly to the woolen polishing cloth and perform fine polishing on the processed surface. The conditions for fine polishing are: loading force of 0.2MPa, grinding disc speed of 800rpm, spindle speed of 50rpm, and polishing time of 50min.

[0056] Then, ultrasonic cleaning was performed sequentially with deionized water and ethanol, with the same ultrasonic cleaning parameters each time, all at a power density of 0.3 W / cm³. 2 The frequency was 40kHz and the temperature was 35℃; the processed porous brass material was then obtained by vacuum drying, with a vacuum degree of -1×10⁻¹⁰. -5 Pa, temperature 80℃, time 30min.

[0057] Example 3

[0058] A polishing method for porous tin bronze material includes the following steps: sintered porous tin bronze material (with an average pore size of 50 μm) is placed on an HMP-1AE type automatic polishing equipment and fixed with a fixture; the surface to be processed is rough-ground and leveled using 180-grit wet sandpaper; the rough-ground conditions are: a loading force of 0.3 MPa, a grinding disc speed of 120 rpm, a spindle speed of 2 rpm, and a polishing time of 4 min;

[0059] Then, use coarse and fine wet sandpaper to finely grind the surface after coarse grinding until the scratches on the surface are shallow and in the same direction.

[0060] The coarse wet sandpaper has a mesh size of 500. The sanding conditions are: a loading force of 0.2 MPa, a grinding disc speed of 500 rpm, a spindle speed of 18 rpm, and a sanding time of 10 min.

[0061] The fine wet sandpaper has a mesh size of 1000. The sanding conditions are: a loading force of 0.1 MPa, a grinding disc speed of 600 rpm, a spindle speed of 30 rpm, and a sanding time of 20 min.

[0062] Then, apply polishing paste of specification W1.5 evenly to the velvet polishing cloth and perform fine polishing on the processed surface. The conditions for fine polishing are: loading force of 0.3MPa, grinding disc speed of 750rpm, spindle speed of 75rpm, and polishing time of 45min.

[0063] Then, ultrasonic cleaning was performed sequentially with deionized water and ethanol, with the same ultrasonic cleaning parameters each time, all at a power density of 0.3 W / cm³. 2 The frequency was 40kHz and the temperature was 35℃; the processed porous tin bronze material was then obtained by vacuum drying, with a vacuum degree of 1×10⁻⁶. -5 Pa, temperature 80℃, time 30min.

[0064] The porous metal materials processed in Examples 1-3 were tested, and the results are as follows: Figure 1-3 As shown. Figure 1 The image shows the OM morphology of the polished surface of the porous brass in Example 1, where a is magnified 50 times and b is magnified 100 times. Figure 2 The image shows the OM morphology of the polished surface of the porous brass in Example 2, where a is magnified 50 times and b is magnified 100 times. Figure 3 The image shows the OM morphology of the polished surface of the porous tin bronze in Example 3, where a is magnified 50 times and b is magnified 100 times.

[0065] Depend on Figure 1-3 It can be seen that when processed using the process and parameters described in this invention, the pores of the polished surface do not undergo significant deformation or blockage.

[0066] Different process parameters were selected, and porous brass materials were polished according to the method of Example 1. The parameters are shown in Table 1.

[0067] Table 1 shows the parameters for Comparative Examples 1-14.

[0068]

[0069]

[0070] The processed surfaces of the porous metal materials in Examples 1-3 and Comparative Examples 1-16 were observed and their surface porosity was measured. The results are shown in Table 2.

[0071] The method for detecting porosity of processed surfaces is as follows: using the image method, Image Pro Plus software is used to process the OM image of the porous material, and the area of ​​the entire image and the pores is statistically analyzed. The ratio of the pore area to the area of ​​the entire image is the surface porosity.

[0072] Table 2 Detection Results

[0073]

[0074]

[0075] As can be seen from the results in Table 2, the present invention combines step-by-step grinding and polishing processes, and selects appropriate process parameters to obtain high-performance processed parts with no blockage on the processed surface and complete pore structure.

[0076] Typical OM (Metal Oxide) morphology of the polished surface of porous brass in Comparative Examples 1-16 are shown below. Figure 4-11 As shown, Figure 4-11 The images shown are magnified OM (Ore morphology) images of the polished surfaces of porous brass in Comparative Examples 1, 3, 5, 7, 9, 11, 13, and 15, respectively, at 100x magnification.

[0077] Depend on Figure 4-11 It can be seen that when the parameters of the comparative ratio are used for processing, the processing surface of the porous brass is significantly blocked and the pore structure is deformed.

[0078] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A grinding and polishing method for porous metal materials, characterized in that, The process includes the following steps: taking sintered porous metal material and sequentially performing coarse grinding, fine grinding, fine polishing, cleaning, and drying to obtain the processed porous metal material; The conditions for rough grinding are: a loading force of 0.2-0.5 MPa, a grinding disc speed of 100-400 rpm, a spindle speed of 0-10 rpm, and a grinding time of 1-5 min. Use coarse wet sandpaper and then fine wet sandpaper for fine sanding in sequence; For fine grinding, the grit of the coarse wet sandpaper is 400-800 grit, and the grinding conditions are: a loading force of 0.1-0.3MPa, a grinding disc speed of 500-800rpm, a spindle speed of 10-30rpm, and a grinding time of 5-15min. For fine grinding, the grit of the fine wet sandpaper is 1000-5000 grit, and the grinding conditions are: a loading force of 0.05-0.15MPa, a grinding disc speed of 500-1000rpm, a spindle speed of 20-50rpm, and a grinding time of 10-30min. For rough grinding, use 80-250 grit sandpaper. The conditions for fine polishing are: a loading force of 0.2-0.35 MPa, a grinding disc speed of 500-1500 rpm, a spindle speed of 30-100 rpm, and a polishing time of 30-120 min. The average pore size of porous metallic materials is ≤200μm.

2. The grinding and polishing method for porous metal materials according to claim 1, characterized in that, When fine grinding, the grit ratio of coarse to fine wet sandpaper should be 1:2-5.

3. The grinding and polishing method for porous metal materials according to claim 1, characterized in that, During fine polishing, the ratio of grinding disc speed to spindle speed is 10-25:

1.

4. The grinding and polishing method for porous metal materials according to claim 1, characterized in that, For fine polishing, the polishing compound should be in the size range of W0.5-W3.

5.

5. The grinding and polishing method for porous metal materials according to claim 1, characterized in that, For fine polishing, the polishing cloth is made of one of the following materials: velvet, wool, or velvet.

6. The grinding and polishing method for porous metal materials according to claim 1, characterized in that, The cleaning process is ultrasonic cleaning.

7. The grinding and polishing method for porous metal materials according to claim 6, characterized in that, The power density of ultrasonic cleaning is 0.3-0.8 W / cm³. 2 The frequency is 40-80kHz and the temperature is 30-50℃.

8. The grinding and polishing method for porous metal materials according to claim 1, characterized in that, The drying process is vacuum drying.

9. The grinding and polishing method for porous metal materials according to claim 8, characterized in that, The vacuum degree of vacuum drying is 1×10 -5 -5×10 -5 Pa, temperature 75-200℃, time 30-120min.

10. The grinding and polishing method for porous metal materials according to claim 1, characterized in that, Porous metal materials are made of one of the following materials: aluminum, aluminum alloy, copper, copper alloy, stainless steel, intermetallic compounds, titanium alloy, and magnesium alloy.

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