Progressive micro-nano modification method for metal surfaces

Abstract

A progressive metal surface micro-nano-modification method includes the following steps: contacting a modification tool with a designable edge to the surface of a substrate, rotating the modification tool in a localized area to compress the surface of the material, and preset process parameters using 3D modeling software; after the tool has processed the entire surface, it moves downward to the previously compressed concave surface; this process continues until the surface material is compressed to a preset thickness, thereby achieving the goals of grain refinement and improved surface properties. This method allows for flexible and design-based surface modification of workpieces with complex shapes, and has the advantages of high adhesion, no pollution, and low cost.

Description

[Technical Field]

[0001] The present invention relates to the field of surface engineering, and in particular to a progressive method for micro-nano modification of metal surfaces. [Background technology]

[0002] Surface engineering technology is important for modifying products and improving their properties (such as wear resistance, corrosion resistance, and heat resistance), and is known as one of the key manufacturing technologies of the 21st century. Based on the excellent properties exhibited by the size effects of micro- and nano-materials, surface micro- and nano-modification technology, developed by combining micro- and nano-technology with surface engineering, has become a hot research topic in surface engineering. However, current modification technologies have many issues, such as poor adhesion, difficulty coating materials with complex shapes, low yield, low efficiency, and environmental unfriendliness, making it difficult to achieve product performance that meets economic, environmental, and sustainability requirements. Summary of the Invention

[0003] The present invention provides a progressive metal surface micro-nano modification method, which can flexibly and designably modify the surface of workpieces with complex shapes, and has the advantages of high adhesion, no pollution, and low cost.

[0004] In order to achieve the above objectives, the present invention adopts the following technical solutions: A progressive metal surface micro-nano modification method, which comprises: (1) contacting an end of a modification tool with a surface of a substrate and presetting operation parameters of the modification tool through three-dimensional modeling software; (2) rotating the modification tool at a localized region of the substrate surface and operating according to the operating parameters preset in step (1) to compress the substrate surface; (3) after treating the entire surface of the substrate with the modification tool, the modification tool moves downward to the previously compressed concave surface; (4) repeating steps (2) and (3) until the substrate is compressed to the preset thickness.

[0005] In the above steps, the end of the modification tool is a ball end, a flat end, or a pin end. The operating parameters in step (1) include a motion trajectory, a tool rotation speed, a feed rate, a single-layer extrusion rate, a processing pass, and a secondary feed overlap rate. The motion trajectory can be unidirectional, reciprocating, grid, or spiral, etc. The tool rotation speed is 1000 rpm to 30,000 rpm, the feed rate is 1000 mm / min to 6,000 mm / min, the single-layer extrusion rate is 0.01 mm to 0.1 mm, the processing pass is 10 to 30 times, and the secondary feed overlap rate is 2% to 10%. In step (3), the downward movement distance is controlled according to the preset single-layer extrusion rate. Throughout the entire process, the modification tool is assisted by an ultrasonic vibration device, and the static pressure of the ultrasonic vibration of the ultrasonic vibration device is 150 N to 350 N and the amplitude is 2 μm to 7 μm. The entire treatment process can provide the necessary treatment atmosphere and lubrication conditions according to different substrates and desired purposes.

[0006] The beneficial effects are: This invention provides a progressive metal surface micro-nano modification method that integrates mechanical and numerical control with micro-nano manufacturing and surface engineering techniques, integrating rotary friction, ultrasonic vibration, numerical control technology, and surface metallurgy into the field of metal surface engineering. By utilizing numerical control, computer-aided technology is fully utilized to effectively achieve micro-nano surface manufacturing of various complex 3D metal structures, improving modification efficiency and accuracy. Furthermore, a mechanical action is employed, namely, the progressive metal surface micro-nano modification technology (MIMST, Micro-nano Incremental Mechanical Surface Treatment) process. This process directly applies ultrasonic excitation to the material surface, achieving the self-growth of surface micro-nano structures. The micro-nanocrystalline layer significantly improves the mechanical, physical, and chemical properties of the surface material. This significantly improves the material's ability to undergo further chemical processing (such as carburizing, nitriding, and particle metallization). The mechanical processing method, accompanied by an increase in surface activity energy, offers great potential and convenience for the further development of novel functional composite surfaces. The processing efficiency of the method of the present invention is relatively high, there is no obvious separation interface between the substrate and the nanocrystalline layer, and it has the advantages of high adhesion, no pollution, and low cost, so that green production of surface engineering can be achieved. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic diagram of a modification tool with a ball end. [Figure 2] 1 is a schematic illustration of the through-thickness microstructure and stress / strain of the modified layer according to the method of the present invention. [Figure 3] 1 is a schematic diagram of the surface texture structure of a material modified by the method of the present invention. [Figure 4] 1 is a diagram illustrating the principle of the modification technology in the method of the present invention, where ΔZ is the single-layer extrusion rate, ωt is the tool rotation speed, Vt is the tool feed linear speed, Rt is the tool radius, Δd is the secondary feed overlap rate, Δt is the total extrusion rate, and NP is the processing pass. [Figure 5]FIG. 2 is a graph showing the friction coefficient curve and surface texturing of the modified material in Example 1 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0008] The present invention will now be described in detail in conjunction with the drawings and specific examples.

[0009] Example 1 As shown in FIG. 4, a progressive metal surface micro-nano modification method includes the following steps: The end of the 8mm ball-end modified tool shown in Figure 1 was brought into contact with the 7075-T6 aluminum alloy substrate. Under oil lubrication conditions, the operating parameters of the modified tool were preset using 3D modeling software: tool rotation speed: 18,000 rpm, tool feed linear speed: 6,000 mm / min, single-layer extrusion rate: 0.03 mm, and secondary feed overlap rate: 2%. The modified tool rotated in a local area and operated according to the preset trajectory to compress the surface of the material. Once the entire surface was processed, it moved downward to the previously compressed concave surface. The movement distance was controlled according to the preset single-layer extrusion rate. This process continued until the surface material was compressed to the preset thickness.

[0010] Compared with the 7075-T6 aluminum alloy substrate, the microhardness of the modified material increased from 79.4 HV to 125.1 HV, an increase of 57.6%, and as shown in Figure 5, compared with the 7075-T6 aluminum alloy substrate, the average friction coefficients in the 0°, 45°, and 90° directions decreased from 0.395 to 0.126, 0.105, and 0.107, respectively.

[0011] Example 2 As shown in FIG. 4, a progressive metal surface micro-nano modification method includes the following steps: The end of the 8mm ball-end modified tool shown in Figure 1 was brought into contact with the 7075-T6 aluminum alloy substrate. Under oil lubrication conditions, the operating parameters of the modified tool were preset using 3D modeling software: tool rotation speed: 6000 rpm, tool feed linear speed: 4000 mm / min, single-layer extrusion rate: 0.02 mm, and secondary feed overlap rate: 2%. The modified tool rotated in a local area and operated according to the preset trajectory to compress the surface of the material. Once the entire surface was processed, it moved downward to the previously compressed concave surface. The moving distance was controlled according to the preset single-layer extrusion rate. This process continued until the surface material was compressed to the preset thickness.

[0012] Compared with the 7075-T6 aluminum alloy substrate, the microhardness of the material after modification increased from 79.4 HV to 118.6 HV, an increase of 49.4%, and the average friction coefficient decreased from 0.395 to 0.126, respectively, compared with the 7075-T6 aluminum alloy substrate.

[0013] Example 3 As shown in FIG. 4, a progressive metal surface micro-nano modification method includes the following steps: The end of the 8mm ball-end modified tool shown in Figure 1 was brought into contact with the 7075-T6 aluminum alloy substrate. Under oil lubrication conditions, the operating parameters of the modified tool were preset using 3D modeling software: tool rotation speed: 12,000 rpm, tool feed linear speed: 4,000 mm / min, single-layer extrusion rate: 0.03 mm, and secondary feed overlap rate: 8%. The modified tool rotated in a local area and operated according to the preset trajectory to compress the surface of the material. Once the entire surface was processed, it moved downward to the previously compressed concave surface. The movement distance was controlled according to the preset single-layer extrusion rate. This process continued until the surface material was compressed to the preset thickness.

[0014] Compared with the 7075-T6 aluminum alloy substrate, the microhardness of the material after modification increased from 79.4 HV to 104.6 HV, an increase of 31.7%, and the average friction coefficient decreased from 0.395 to 0.269, respectively, compared with the 7075-T6 aluminum alloy substrate.

[0015] As shown in the schematic diagram of the full-thickness microstructure and stress / strain of the modified layer in Figure 2, plastic deformation tends to reduce the grain size of the material, and the frictional heat generated at the interface between the modified tool and the material surface also helps to readjust the surface grain size. As shown in the schematic diagram of the surface texture structure of the modified material in Figure 3, plastic flow can also lead to surface texturing of the material, which can effectively improve its tribological properties. Therefore, the newly generated surface properties are due to the cooperative action of residual stress, grain refinement, and texturing.

[0016] It should be noted that the above are only preferred embodiments of the present invention, and those skilled in the art may make some improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be regarded as within the protection scope of the present invention.

Claims

1. A metal surface micro-nano modification method, (1) contacting an end of a modification tool with a surface of a substrate and presetting operation parameters of the modification tool through three-dimensional modeling software; (2) rotating the modification tool at a high speed in a localized area of ​​the substrate surface at a rotation speed of 1000 rpm to 30000 rpm, and operating according to the operating parameters preset in step (1) to compress the substrate surface; (3) after treating the entire surface of the substrate with the modification tool, the modification tool moves to a concave surface of the substrate surface formed by compressing the substrate in the thickness direction; (4) repeating steps (2) and (3) until the substrate is compressed to a preset thickness; The operating parameters in step (1) are: according to the operating trajectory of the modified tool, the feed speed of the modified tool is 4000mm / min-6000mm / min; in the multiple-pass processing, the single-layer extrusion amount of the compressed material in one pass is 0.01mm-0.1mm; and the multiple-pass processing is performed, and the processing passes are 10-30 times; During the whole treatment process, the modification tool is assisted by an ultrasonic vibration device, and ultrasonic excitation is introduced into the surface of the substrate, so that the surface micro-nano structure of the substrate grows by itself to form a micro-nano crystal layer; and the friction heat generated by the high-speed rotation causes plastic flow in the substrate, so that the grain size on the surface of the substrate is readjusted, and the separation interface between the substrate and the micro-nano crystal layer is eliminated; The ultrasonic vibration device has a static pressure of 150N to 350N and an amplitude of 2μm to 7μm. A method for micro-nano modification of metal surfaces.

2. The motion trajectory is unidirectional, reciprocating, grid, or spiral. The method for micro-nano modification of a metal surface according to claim 1.

3. The moving distance of the substrate in the thickness direction in step (3) is controlled according to a preset single layer extrusion amount. The method for micro-nano modification of a metal surface according to claim 1.

4. The entire treatment process is characterized by the ability to provide atmospheric gas and lubrication conditions according to the substrate to be treated and the treatment purpose. The method for micro-nano modification of a metal surface according to claim 1.

5. The end of the modification tool is a ball end, a flat end, or a pin end. The method for micro-nano modification of a metal surface according to claim 1.

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