A powder-repellent surface, its production and use

Abstract

The present application provides a kind of powder-repellent surface and its preparation method and application, the surface is formed with at least one layer of nano corrugated structure, the characteristic size of nano corrugated structure is 1-100 μm;Preferably, surface is sequentially formed from top to bottom with the first structure and the second structure of the non-parallel direction of corrugation, the characteristic size of second structure is less than the characteristic size of first structure, the average depth of first structure is greater than second structure, the characteristic size of second structure is 1-5 μm, surface is hard metal surface.Powder-repellent surface is based on the surface texture technology of pulsed laser to modify the surface morphology of metal / alloy substrate, constructs the surface micro-nano structure of micron-sized gully-like protrusion on substrate, reduces the contact area between powder particle and substrate, thereby reduces the adhesion of powder, by tilting surface, powder adhered on substrate can be naturally dropped off.The scheme can be applied to any product, equipment or processing environment that needs to prevent powder pollution, to achieve the effect of greatly reducing the surface powder adhesion area.

Description

Technical Field

[0001] This invention belongs to the field of surface treatment technology, specifically relating to a sparse powder surface, its preparation method, and its application. Background Technology

[0002] Powder refers to fine, dry particles that are widely present in nature. Controlling powder adhesion to surfaces is fundamental to the study of interfacial dynamics. Currently, the gravitational adhesion of large particles larger than millimeters has been extensively studied. However, for micron / nanometer-sized powders, the complex interactions due to van der Waals forces exceeding gravity by approximately three orders of magnitude make adhesion research less systematic and mature. Besides its widespread presence in basic scientific research, powder adhesion also has significant engineering value in industrial production and daily life. For example, in the food industry, powdered foods often adhere to packaging during production, transportation, and use, posing long-term food safety risks. Dust accumulation is a major cause of reduced efficiency over the lifespan of solar panels. Combustion residues can lead to serious malfunctions in engines, cannons, and even spacecraft. Therefore, surfaces resistant to dust adhesion play a crucial role in many fields, such as dust control in food production workshops, dust control for complex machines and systems, and the design and maintenance of special environments, such as clean rooms, semiconductor factories, and extreme standard laboratories in virology.

[0003] Research on superhydrophobic powder adhesion surfaces mainly focuses on reducing the adhesion force between powder and solid surfaces. Existing technologies control powder adhesion by applying electrostatic, flow, or chemical treatments to the powder itself, or by utilizing the self-cleaning properties of superhydrophobic surfaces to clean the deposited powder. These methods suffer from high cost, complex preparation, poor durability, and harsh application conditions, significantly limiting the miniaturization and application scenarios of this technology. Summary of the Invention

[0004] To address the aforementioned problems, the first aspect of this invention provides a powder-repellent surface having at least one layer of nano-ripple structure formed thereon, the characteristic size of which is 1-100 μm. This solution reduces the contact area between the powder and the surface by designing a micro / nano structure surface, thus preventing powder adsorption.

[0005] Preferably, the surface is formed from top to bottom with a primary structure and a secondary structure with non-parallel corrugation directions, and the feature size of the secondary structure is smaller than that of the primary structure.

[0006] Preferably, the average depth of the primary structure is greater than that of the secondary structure.

[0007] Preferably, the feature size of the secondary structure is 1-5 μm.

[0008] Preferably, the surface is a hard metal surface.

[0009] The second aspect of the present invention provides the use of the powder-repellent surface of any one of the first aspects in the preparation of a surface that reduces powder adhesion.

[0010] Preferably, it is used to reduce dust adhesion generated during food or industrial production processes, and the powder surface is used as a machine tool for production.

[0011] The third aspect of the present invention provides a method for preparing a sparse powder surface, comprising the steps of: providing a metal substrate, and using a pulsed laser to ablate the surface of the metal substrate to form at least one layer of nano-wave structure, wherein the characteristic size of the nano-wave structure is 1-100 μm.

[0012] Preferably, a primary structure is formed by laser ablation, and a corrugated secondary structure is formed by the accumulation of molten material below the primary structure during the laser ablation process.

[0013] Preferably, the laser pulse ablation treatment has an average laser power of 5-20W, a wavelength of 355-1064nm, a pulse width of 15-200nm, a pulse repetition frequency of 25-200kHz, a line scan interval of 30-50μm, a scan speed of 300-500mm / s, and 3-5 scans.

[0014] The powder-repellent surface proposed in this invention modifies the surface morphology of a metal / alloy substrate using pulsed laser surface texturing technology. This constructs a micro-nano structure with micron-sized grooves and protrusions on the substrate, reducing the contact area between powder particles and the substrate, thereby reducing powder adhesion. Powder adhering to the substrate can then be naturally detached by tilting the surface or applying driving forces such as micro-vibration or micro-airflow. This powder-repellent surface is formed through laser texturing, a simple and repeatable process using readily available and low-cost raw materials. This solution is applicable to any product, equipment, or processing environment requiring prevention of powder contamination, achieving a significant reduction in surface powder adhesion area. Attached Figure Description

[0015] For ease of description, only the parts relevant to the invention are shown in the accompanying drawings.

[0016] Figure 1 This is a schematic diagram of the structure of a sparse powder surface in one embodiment of the present invention;

[0017] Figure 2 This is a schematic diagram of the structure of a sparse powder surface in one embodiment of the present invention;

[0018] Figure 3 This is a schematic diagram of the structure of the sparse powder surface in another embodiment of the present invention;

[0019] Figure 4 This is a schematic diagram of the secondary structure of the sparse powder surface in another embodiment of the present invention;

[0020] Figure 5 This is a microscopic observation of the secondary structure of the sparse powder surface in another embodiment of the present invention;

[0021] Figure 6 This is a comparison diagram of the powder adhesion force between the sparse powder surface and the original stainless steel surface in another embodiment of the present invention;

[0022] Figure 7 This is a comparison image of corn starch adhesion on the workpiece surface before and after laser surface treatment, according to another embodiment of the present invention.

[0023] Figure 8 This is a comparison diagram of the powder adhesion force between the sparse powder surface and the original stainless steel surface in another embodiment of the present invention;

[0024] Figure 9 This is a comparison diagram of the adhesion of baking soda powder on the workpiece surface before and after laser surface treatment in another embodiment of the present invention;

[0025] Figure 10 This is a comparison diagram of the powder adhesion force between the sparse powder surface and the original stainless steel surface in another embodiment of the present invention;

[0026] Figure 11 This is a comparison image of flour adhesion on the workpiece surface before and after laser surface treatment, according to another embodiment of the present invention.

[0027] Figure 12 This is a comparison diagram of the powder adhesion force between the sparse powder surface and the original stainless steel surface in another embodiment of the present invention;

[0028] Figure 13 This is a comparison image of coffee powder adhesion on the workpiece surface before and after laser surface treatment, as shown in another embodiment of the present invention. Detailed Implementation

[0029] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. The specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention. Unless otherwise specified, the embodiments and features described herein can be combined with each other.

[0030] In this invention, dust is defined as powdery solid particles with a particle size of 10-1000 μm. Dust in this size range is abundant in various industrial production processes and easily adheres to the surfaces of various equipment, making it difficult to remove.

[0031] Figure 1 , Figure 2This is a schematic diagram of the structure of a sparse powder surface in one embodiment of the present invention. A primary structure with groove-like protrusions is formed on the substrate surface using a pulsed laser. The characteristic size of this primary structure, i.e., the gap between its grooves, is typically 5-100 μm. Specifically, this size is determined according to the size of the powder particles in the application scenario. Figure 1 As shown, most of the powder particles that easily adhere to the surface have a particle size larger than the gap between the grooves. Therefore, the powder particles accumulate at the top of the groove-like protrusions, reducing the contact area with the substrate surface. Tilting the substrate can remove the powder from the surface.

[0032] like Figure 2 As shown, powder particles smaller than the inter-groove gaps of the primary structure may become trapped in the grooves, increasing the contact area between the powder and the substrate, thus increasing adhesion and making removal more difficult. Therefore, in a preferred embodiment, it is further proposed to form the primary structure on the secondary structure, wherein the feature size of the secondary structure is smaller than the inter-groove gaps of the primary structure. Figure 3 This is a schematic diagram of the structure of the sparse powder surface in this embodiment. Figure 4 This is a schematic diagram of the secondary structure of the sparse powder surface in this embodiment. Figure 5 This is a microscopic image of the secondary structure of the sparse powder surface in this embodiment. In this embodiment, a corrugated secondary structure is constructed at the bottom of the trenches in the primary structure, thereby reducing the adhesion between the tiny powder particles trapped in the trenches and the substrate. The characteristic size of this secondary corrugated structure is 1 μm.

[0033] In a specific embodiment, the method for preparing the sparse powder surface is as follows: using a metal or alloy material as the workpiece, a pre-fabricated micron-scale microstructure is formed on the workpiece surface through a pulsed laser surface texturing process. This microstructure consists of micron-level groove-like protrusions. Further, during the pulsed laser ablation process, the aforementioned metal or alloy material is melted and deposited to form a secondary corrugated structure within the heat-affected zone.

[0034] The following Examples 1-4 demonstrate the powder adhesion effect of the powder-repellent surface provided by the present invention through designed experiments.

[0035]

Example 1

[0036] A method for constructing a sparse powder surface using laser, wherein the workpiece is made of stainless steel, and a 1064nm pulsed laser is used. instrument The surface micro / nanostructure was fabricated, consisting of micron-sized groove-like protrusions. The laser was used with an average power of 5W, a wavelength of 355nm, a pulse width of 15ns, a pulse repetition frequency of 25kHz, a line scan interval of 30μm, a scanning speed of 500mm / s, and 3 scans. In this embodiment, corn starch was used to test the adhesion effect of loose powder; the minimum particle size of the corn starch used was approximately 10μm. By tilting the workpiece substrate, the powder adhering to the substrate... That's allIt falls off naturally; the tilt angle used in this embodiment is 45°. Figure 6 The image shows a comparison of the powder adhesion between the powder-coated surface prepared in this embodiment and the original stainless steel surface. The square portion represents the processed surface, where no powder adhesion is visible under the camera, while the unprocessed surface shows powder adhesion (white lumps). Figure 7 The images show a comparison of corn starch adhesion on the workpiece surface before and after laser surface treatment, as shown below. Figure 7 As can be seen, after laser surface texturing, the adhesion area of ​​corn starch on the workpiece surface decreased from 31.1% to 0.4%, and the effective powder dispersing area increased by 77 times.

[0037]

Example 2

[0038] In this embodiment, the workpiece is made of stainless steel, the line scan interval is 50 μm, and the number of scans is 5. All other conditions are the same as in Example 1. This embodiment uses baking soda to test the powder adhesion effect. The smallest amount of baking soda used... grain The diameter is about 15μm; the workpiece substrate is tilted at a 75° angle to allow the powder adhering to the substrate to fall off naturally. Figure 8 A comparison of the powder adhesion between the powder surface prepared in this embodiment and the original stainless steel surface clearly shows that the central square block area has less adsorption. Figure 9 The image shows a comparison of the adhesion of baking soda powder on the workpiece surface before and after laser surface treatment. The adhesion area of ​​baking soda powder on the workpiece surface decreased from 20.4% to 0.7%, and the effective powder-dispersing area increased by 29 times.

[0039]

Example 3

[0040] In this embodiment, the workpiece is made of stainless steel. The laser average power is 20W, wavelength is 1064nm, pulse width is 200ns, pulse repetition frequency is 600kHz, line scan interval is 50μm, and the number of scans is 5. All other conditions are the same as in Example 1. This embodiment uses flour to conduct an experiment on powder adhesion. The minimum... grain The diameter is about 10μm; the workpiece substrate is tilted at a 75° angle to allow the powder adhering to the substrate to fall off naturally. Figure 10 A comparison of the powder adhesion force between the powder-coated surface prepared in this embodiment and the original stainless steel surface clearly shows that the square processed surface has less powder adhesion compared to the unprocessed surface. Figure 11 The image shows a comparison of flour adhesion on the workpiece surface before and after laser surface treatment. The area of ​​flour adhesion on the workpiece surface decreased from 7.7% to 1.6%, and the effective powder dispersing area increased by 4 times.

[0041]

Example 4

[0042] In this embodiment, the workpiece is made of stainless steel, the line scan interval is 50 μm, the scanning speed is 300 mm / s, and the other conditions are the same as in Example 1. This embodiment uses coffee powder to conduct an experiment on powder adhesion. The minimum [unclear - likely a specific measurement] is used. grain The diameter is about 20μm; the workpiece substrate is tilted at a 75° angle to allow the powder adhering to the substrate to fall off naturally. Figure 12 A comparison of the powder adhesion force between the powder-coated surface prepared in this embodiment and the original stainless steel surface clearly shows that the square processed surface has less powder adhesion compared to the unprocessed surface. Figure 13 The image shows a comparison of coffee powder adhesion on the workpiece surface before and after laser surface treatment. The adhesion area of ​​coffee powder on the workpiece surface decreased from 14.0% to 1.2%, and the effective powder dispersing area increased by 11 times.

[0043] This invention proposes a laser-based surface texturing method to construct powder-repellent surfaces on metal / alloy substrates. By utilizing a rationally designed surface micro / nanostructure, the adhesion strength between the substrate and the powder is reduced, achieving powder-repellent functionality. This solves the problem of powder adhesion in existing technologies and represents a key step in realizing powder-repellent engineering on solid surfaces, significantly enhancing the application prospects of powder-repellent surfaces. Furthermore, it facilitates the creation of various unique functional systems based on designed powder-repellent properties, or the flexible design of powder-repellent surfaces for different new applications.

[0044] Although the contents of this application have been specifically shown and described in conjunction with preferred embodiments, those skilled in the art should understand that any changes in form and detail made to this application without departing from the spirit and scope of this application as defined by the appended claims and without inventive effort are within the scope of protection of this application.

Claims

1. A powder-repellent surface, characterized in that, The surface is formed with two layers of micro-nano corrugated structures, the characteristic size of which is 1-100 μm. The two layers of micro-nano corrugated structures are respectively formed from top to bottom on the surface as a primary structure and a secondary structure with non-parallel corrugation directions. The characteristic size of the secondary structure is 1-5 μm, which is smaller than the characteristic size of the primary structure.

2. The powder-coated surface according to claim 1, characterized in that, The average depth of the primary structure is greater than the average depth of the secondary structure.

3. The powder-coated surface according to claim 1, characterized in that, The surface is a hard metal surface.

4. The use of the powder-repellent surface according to any one of claims 1-3 in the preparation of a surface that reduces powder adhesion.

5. The application according to claim 4, characterized in that, The powder is dust generated during food or industrial production processes, and the surface of the powder is a machine tool used in production.

6. A method for preparing a sparse powder surface as described in any one of claims 1-3, characterized in that, The process includes the following steps: providing a hard metal substrate, ablating the surface of the hard metal substrate with a pulsed laser to form a primary structure through laser ablation, and simultaneously forming a corrugated secondary structure by molten material accumulating below the primary structure during the laser ablation process; the average laser power of the pulsed laser ablation process is 5-20W, the wavelength is 355-1064nm, the pulse width is 15-200ns, the pulse repetition frequency is 25-600kHz, the line scan interval is 30-50μm, the scanning speed is 300-500mm / s, and the number of scans is 3-5.

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