Composite modified antifriction wear-resistant surface and laser two-step processing method thereof

Abstract

The invention discloses a composite modified antifriction wear-resistant surface and a laser two-step processing method thereof. The composite modified antifriction wear-resistant surface is provided with a surface texture, a solid lubricating material and a surface hardening layer. The surface texture is processed through a laser surface texture technology; the solid lubricating material is composed of a low-melting-point soft metal material and a two-dimensional layered material, the texture is pre-filled with the solid lubricating material in a mechanical tamping mode, and then the texture is further filled with the solid lubricating material in an ablated mode through laser line scanning treatment. The surface hardening layer is formed while the solid lubricant is further ablated and filled during laser line scanning. The laser two-step machining method specifically comprises the steps that firstly, ablation is conducted on the surface one by one, and a regular surface texture array is formed through machining; in the second step of surface line scanning machining, the filled solid lubricating material is ablated, meanwhile, overall hardening of the surface is achieved, and a recast layer formed in the first step of texture machining process is eliminated.

Description

Technical Field

[0001] The present invention relates to the technical field of composite modification of metal material surfaces, and in particular to a composite modified anti-friction and wear-resistant surface and a two-step laser processing method thereof. Background Technology

[0002] Authoritative statistics show that energy consumption and mechanical parts failure due to friction account for 30% and over 80% respectively. Therefore, in-depth research on tribology issues has far-reaching economic and social significance in today's world of energy conservation and emission reduction. How to reduce failures caused by material friction and wear, and thus improve the reliability, stability and service life of mechanical systems has always been the research focus in the field of tribology.

[0003] Surface engineering improves the tribological properties of material surfaces by using physical, chemical or mechanical methods or technologies without affecting the excellent properties of the base material itself, and can effectively delay and control surface failures caused by friction, wear and corrosion. Among them, surface texturing, surface hardening and solid lubrication technologies are widely used to improve the tribological properties of key components of mechanical equipment.

[0004] Surface texturing technology has been proven to improve the tribological properties of material surfaces under dry friction, boundary, mixed, elastic fluid dynamics and other conditions. Its principle is generally considered to act as a tiny hydrodynamic lubricated bearing, reduce direct contact of the friction interface, act as a micro oil reservoir and capture wear debris. However, under harsh working conditions, due to the reduction of the effective bearing area of ​​the textured surface, the wear of the material during the friction process will lead to a reduction in the service life of the texture, and the wear failure of the surface texture will lead to higher friction resistance and wear. In addition, the recast layer formed around the texture during the laser surface texturing process will evolve into hard abrasive particles during the friction and wear process, causing more serious abrasive wear. Solid lubricants improve friction and wear resistance by releasing lubricating components during the friction process. In particular, the interlayer slip of two-dimensional layered materials in the friction contact area can reduce the direct contact of the friction pair materials, thereby reducing wear. However, due to the poor adhesion of solid lubricants and displacement during the friction process, they will fall off, which will reduce the durability of solid lubricants. Surface hardening can greatly improve the wear resistance of the material surface. Combining it with surface texture and solid lubrication technology to form a composite modified surface can better meet the needs of increasingly complex friction conditions.

[0005] Therefore, the present invention proposes a composite modified anti-friction and wear-resistant surface and its two-step laser processing method, which combines surface texture, surface hardening and solid lubrication technology, which will help improve the durability of surface texture and solid lubricant, and the hardened surface also has high wear resistance. The above technology will help improve the tribological performance of friction pairs of key parts of mechanical equipment under complex working conditions. Summary of the invention

[0006] The purpose of the present invention is to address the material friction and wear problems caused by direct contact of friction pairs under boundary lubrication conditions, and the problems that the modified surface prepared by a single surface treatment process has insufficient durability and the friction and wear resistance cannot meet the increasingly improved actual working conditions. A composite modified friction and wear resistant surface and a laser two-step processing method thereof are proposed. The mechanism is that solid lubricating materials are filled in the surface texture, and the solid lubricating materials will be released to the friction contact surface during the friction and wear process. In addition, the abrasive particles formed during the friction and wear process are captured by the texture filled with solid lubricants mainly composed of soft metal materials, which reduces abrasive wear on the one hand and squeezes the solid lubricating materials to the friction contact surface on the other hand. The solid lubricating materials released or squeezed to the friction contact surface can reduce direct contact and improve the friction and wear resistance of the surface. The hardened surface can have better wear resistance, improve the wear resistance of the effective load-bearing area of ​​the textured surface, and thus improve the durability of the surface texture. The above synergistic effect enables the composite modified surface to have excellent friction and wear resistance and a longer service life.

[0007] The composite modified anti-friction and wear-resistant surface has a surface texture, a solid lubricant and a surface hardened layer. The surface texture is processed by laser surface texturing technology; the solid lubricant is filled in the texture by mechanical filling and laser ablation; the surface hardened layer is formed while the solid lubricant is further ablated and filled by laser line scanning.

[0008] The surface texture is a regular pattern array formed by laser processing and ablation one by one. The pattern can be a circle or polygon with a diameter or circumscribed circle diameter of 80~200 μm. The area density of the surface texture can be set to 10%~25% according to actual working conditions.

[0009] The solid lubricating filling material is composed of a low-melting-point soft metal material and a two-dimensional layered material, wherein the soft metal material is a spherical powder with a particle size of 15-25 μm, and the two-dimensional layered material is a submicron-sized powder. The two are fully mixed in a certain proportion, pre-filled in the texture by mechanical filling and pressing, and then further ablated and filled in the texture by laser line scanning.

[0010] The surface hardened layer is formed while the laser line scanning further ablates and fills the solid lubricant. The rapid heating and cooling mechanism of the laser line scanning surface processing causes a phase change on the surface, generates residual compressive stress, and forms a hardened layer with a thickness of about 10~30 μm.

[0011] ​A composite modified anti-friction and wear-resistant surface and a two-step laser processing method thereof, characterized in that the method comprises the following steps: (1) pretreatment of the base material: mechanical grinding and polishing are performed to obtain a base material surface with Ra≈0.02, and a clean and dry base material surface is obtained by ultrasonic cleaning and drying; (2) the first step of laser processing: the base material is placed on a laser processing workbench, a pre-designed regular texture array is introduced, and then laser processing and ablation are performed one by one to obtain a laser textured surface; (3) pre-filling of solid lubricating material: first, the low-melting-point soft metal material and the two-dimensional layered material in the solid lubricating material are fully mixed in a certain proportion, and pre-filled in the texture by mechanical filling and pressing; (4) the second step of laser processing: the textured workpiece pre-filled with solid lubricating material is placed on the workbench and laser line scanning is performed.

[0012] In summary, the present invention proposes a new laser integrated processing method for obtaining a composite modified surface, which can give full play to the respective advantages of surface hardening, surface texturing and solid lubrication technology. The synergistic effect of the three in terms of friction reduction and wear resistance can effectively improve the friction reduction and wear resistance of friction pairs of key parts of mechanical equipment. Brief Description of the Figures

[0013] Figure 1 This is a schematic diagram of the laser two-step processing method for composite modified anti-friction and wear-resistant surface of the present invention.

[0014] Figure 2 This is an overall schematic diagram of the composite modified anti-friction and wear-resistant surface of the present invention.

[0015] Figure 3 is a schematic cross-sectional view of a textured surface.

[0016] Figure 4 Is a schematic diagram of the surface texture filled with solid lubricant.

[0017] Figure 5 is a schematic diagram of the workpiece cross section after the second step of laser line scanning processing Specific implementation method

[0018] The following is combined with the attached Figures 1-5 And specific embodiments further illustrate the present invention, but the protection scope of the present invention is not limited thereto.

[0019] Reference Attachment Figure 1 , the laser two-step process for processing a composite modified anti-friction and wear-resistant surface according to the present invention comprises the following specific steps:

[0020] Step 1: Pretreatment of the base material (4). Use 400 mesh, 800 mesh, 1200 mesh and 2000 mesh sandpaper for grinding, and use a grinder to polish the surface to obtain a base material surface with Ra≈0.02, and then use ultrasonic cleaning and drying to obtain a clean and dry base material surface.

[0021] Step 2: First step of laser processing. Place the base material (4) on the laser processing workbench and import the pre-designed regular texture array, with a processing area density of 15% and a regular hexagonal array with a circumscribed circle diameter of 150 μm. Then perform laser processing and ablation one by one to obtain a laser textured surface. The specific laser processing parameters are as follows: laser power 20 W, scanning speed 1000 mm / s, frequency 1.5 MHz, pulse number 1, pulse width 300 ps, ​​repeated processing times 20 times, according to the attached Figure 1 The scanning path shown in the first step of laser processing scans and processes the micro textures one by one. In the process of processing the texture, a recast layer (5) is inevitably produced. Finally, the following is obtained Figure 3 Surface texture shown.

[0022] Step 3: Pre-filling of solid lubricant material. The low melting point soft metal material (6) and the two-dimensional layered material (7) in the solid lubricant material (2) are fully mixed in a ratio of 9:1, and pre-filled into the texture by mechanical filling and pressing to obtain a textured surface filled with solid lubricant powder, as shown in the attached Figure 4 As shown.

[0023] Step 4: Second step laser processing. Place the textured workpiece pre-filled with solid lubricant (2) on the workbench and perform laser line scanning processing. The specific laser processing parameters are as follows: laser power 100 W, scanning speed 2000 mm / s, frequency 5 MHz, pulse number 1, pulse width 300 ps, ​​line scanning spacing 0.01 mm, according to the attached Figure 1 The scanning path shown in the second laser processing step scans the processed micro textures one by one. After processing, the surface hardened layer (3) is obtained, and the recast layer (5) produced during the first laser processing step is removed.

[0024] The schematic diagram of the obtained composite modified surface is shown in the attached Figure 2 As shown, it specifically includes a surface texture (1), a filled solid lubricating material (2) and a hardened layer (3).

Claims

1. A composite modified anti-friction and wear-resistant surface, characterized in that: The composite modified anti-friction and wear-resistant surface comprises a surface texture (1), a solid lubricating material (2) and a surface hardened layer (3). The surface texture (1) is processed by laser surface texturing technology; the solid lubricating material (2) is filled in the texture by mechanical filling and laser ablation; and the surface hardened layer (3) is formed while further ablating and filling the solid lubricating material (2) by laser line scanning.

2. The composite modified anti-friction and wear-resistant surface according to claim 1, characterized in that: The surface texture (1) is a regular pattern array formed by laser processing and ablation one by one. The pattern can be a circle or a polygon with a diameter or a circumscribed circle diameter of 80 to 200 μm. The area density of the surface texture can be set to 10% to 25% according to actual working conditions.

3. The composite modified anti-friction and wear-resistant surface according to claim 1, characterized in that: The solid lubricating material (2) is composed of a low-melting-point soft metal material (6) and a two-dimensional layered material (7), wherein the soft metal material (6) is a spherical powder with a particle size of 15 to 25 μm, and the two-dimensional layered material (7) is a submicron-sized powder. The two are fully mixed in a certain proportion, pre-filled in the texture by mechanical filling and pressing, and then further ablated and filled in the texture by laser line scanning processing.

4. The composite modified anti-friction and wear-resistant surface according to claim 1, characterized in that: The surface hardened layer (3) is formed while the laser line scanning further ablates the filled solid lubricant. The rapid heating and cooling mechanism during the laser line scanning processing of the surface causes a phase change on the surface, generates residual compressive stress, and forms a hardened layer with a thickness of about 10 to 30 μm.

5. A composite modified anti-friction and wear-resistant surface and a two-step laser processing method thereof, characterized in that: The method comprises the following steps: step 1: pretreatment of a base material (4), mechanical grinding and polishing to obtain a base material surface with Ra≈0.02, and ultrasonic cleaning and drying to obtain a clean and dry base material surface; step 2: first step of laser processing, placing the base material (4) on a laser processing workbench, introducing a pre-designed regular texture array, and then laser processing and ablating one by one to obtain a laser textured surface; step 3: pre-filling of a solid lubricating material (2), firstly, fully mixing a low melting point soft metal material (6) and a two-dimensional layered material (7) in the solid lubricating material according to a certain proportion, and pre-filling them in the texture by mechanical filling and pressing; step 4: second step of laser processing, placing a textured workpiece pre-filled with the solid lubricating material (2) on a workbench, and performing laser line scanning processing, obtaining a hardened layer (3) during the processing and removing a recast layer (5) generated during the texturing treatment, and finally obtaining the composite modified anti-friction and wear-resistant surface.

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