Construction method and preparation process of tough lubricating wear-resistant layer on gear steel surface

Abstract

The invention discloses a construction method and a preparation process of a tough lubricating wear-resistant layer on the surface of gear steel, and the construction method specifically comprises the following steps: firstly, pretreating a gear steel sample and the surface thereof, the pretreatment comprising heat treatment on the gear steel sample and polishing treatment on the surface of the gear steel; a dislocation strengthening layer is introduced to the pretreated surface of the gear steel sample through the laser shock strengthening technology of a laser device; then an ultrafast laser is adopted to machine a bionic microstructure with a lubricating function on the surface of the dislocation strengthening layer; carrying out ion nitriding treatment on the surface of the bionic microstructure so as to obtain a wear-resistant layer with toughness and lubricating functions on the surface of the gear steel sample; according to the method, a high-density dislocation strengthening and toughening layer is induced through laser shock, and ion nitriding strengthening and toughening treatment is carried out by utilizing the permeation promotion effect of high-density dislocation; and then a bionic texture is prepared on the surface of the high-density dislocation layer, and the strengthened and toughened surface has the super-lubricity through the super-lubricity effect of the bionic texture.

Description

Technical Field

[0001] The present invention relates to the technical field of gear steel surface engineering, and in particular to a method for constructing a tough, lubricating, and wear-resistant layer on the surface of a gear steel and a preparation process thereof. Background Art

[0002] Key components of aircraft engines, such as the starting system, fuel system, lubricating oil system, and hydraulic system, all contain numerous friction pairs. Under harsh operating conditions such as high temperatures, high loads, and high speeds, these friction pairs inevitably experience wear. This is particularly true of high-load friction pairs like gears and splines. Wear is a significant factor in reducing the performance, lifespan, and reliability of these friction pairs, and is a major bottleneck hindering the development of high-performance aircraft engines.

[0003] Gear friction pairs are subject to high cyclic stress and large impact forces during operation, and are subject to gear breakage caused by surface deformation (such as thermal deformation, pressure deformation, etc.) and wear failure caused by poor surface lubrication. Therefore, gear friction pairs require their surfaces to have high strength and wear resistance. Gear friction pairs usually use chemical heat treatment methods such as carburizing, nitriding, and cyaniding to strengthen the surface to achieve excellent wear resistance. In addition, surface coatings and surface micro-texturing can also be used to improve their wear resistance. Although the above methods all have certain effects, in fact, these methods do not take into account the simultaneous improvement of the strength and toughness of the friction pair surface and its lubrication performance.

[0004] At present, the ideas to solve this problem mainly focus on self-lubricating wear-resistant coatings, that is, by adding self-lubricating materials (such as soft metals, metal sulfides / selenides / halides, diamond-like carbon, carbon nanotubes, etc.) or alloy powders with specific functions to the coating, to obtain self-lubricating coatings with properties such as friction reduction and wear resistance. Although self-lubricating wear-resistant coatings take into account both surface toughness and lubricity, this method still faces many problems, such as coating quality problems (such as pores, slag inclusions, cracks, etc.), coating film / substrate bonding problems (such as interface matching, etc.), coating peeling problems, etc. Therefore, it is urgent to explore a new technology that takes into account both surface toughness and lubrication properties, so as to achieve a simultaneous improvement in the surface toughness and lubrication properties of the material. Summary of the Invention

[0005] The purpose of the present invention is to solve the technical problems existing in the prior art and provide a method for constructing a tough, lubricating and wear-resistant layer on the surface of gear steel and a preparation process thereof.

[0006] To achieve the above-mentioned purpose, the present invention provides a technical solution: a method for constructing a tough, lubricating, and wear-resistant layer on the surface of gear steel and a preparation process thereof, specifically comprising the following steps:

[0007] S1. Pre-treating the gear steel sample and its surface, including heat treatment of the gear steel sample and polishing of the gear steel surface;

[0008] S2, using laser shock peening technology to introduce a dislocation strengthening layer on the surface of the gear steel sample after pretreatment;

[0009] S3. Processing bionic micro-textures: Using ultrafast lasers to process bionic micro-textures with lubricating function on the surface of the dislocation strengthening layer;

[0010] S4. Ion nitriding treatment: Ion nitriding treatment is performed on the bionic micro-textured surface to obtain a wear-resistant layer with both toughness and lubrication functions on the surface of the gear steel sample;

[0011] The order of step S3 and step S4 can be swapped, that is, the dislocation strengthening layer is first subjected to ion nitriding treatment and then processed to produce the bionic microtexture.

[0012] Preferably, in step S1, after the gear steel sample is heat treated, the surface of the gear steel sample is ground with 800# to 2000# grit sandpaper in sequence, and polished with diamond polishing liquid, and finally the polished gear steel sample is ultrasonically cleaned in acetone solution for 10 minutes.

[0013] Preferably, in step S2, the laser uses a nanosecond pulse laser, and the laser shock peening processing conditions are: wavelength 1064nm, pulse width 15-20ns, pulse frequency 1-5Hz, single pulse energy 1-20J, spot diameter 2-3mm, and spot overlap rate 35%-75%; during the laser shock peening process, a 2mm thick flowing water film is used as a constraining layer and a 100μm thick aluminum foil is used as a protective layer.

[0014] Preferably, in step S3, the ultrafast laser uses a femtosecond laser, and the processing conditions of the femtosecond laser are: single pulse energy 0-5mJ, maximum repetition frequency 100kHz, central wavelength 1035nm, pulse width 300fs, focused spot diameter 15-25μm, processing speed 0.1-6000mm / s; high-precision processing motion platform, X / Y / Z axis positioning accuracy ±1μm, A / B axis positioning accuracy ±3arc / s.

[0015] Preferably, the bionic microtexture processed in step S3 is a natural biological surface structure with a lubricating function, and the natural biological surface structures include marine shellfish texture, cricket foot pad structure, shark skin surface shield scale structure, lotus surface papilla structure, Nepenthes pitcher surface crescent structure, dung beetle body surface pit-shaped structure, and lizard scale structure.

[0016] Preferably, the nitriding conditions of the ion nitriding in step S4 are: nitriding temperature 350-550°C, nitriding gas is a mixture of nitrogen and argon, the volume ratio of nitrogen to argon is 1:2, nitriding pressure is 0-350 Pa, nitriding treatment time is 5-12 h, and nitriding voltage is 100-1000 V.

[0017] Preferably, the ion nitriding treatment in step S4 can be replaced by one of carburizing, carbonitriding, boronizing, sulfurizing, metallizing, and multi-element co-nitriding treatments.

[0018] Beneficial effects of the present invention:

[0019] On the one hand, the present invention induces a high-density dislocation toughening layer through laser shock, and utilizes the promoting effect of high-density dislocations to perform ion nitriding toughening treatment; on the other hand, by preparing a bionic texture on the surface of the high-density dislocation layer and utilizing the superlubrication effect of the bionic texture, the toughened surface is made superlubricious; through the synergistic effect of the above two aspects, a wear-resistant surface with integrated toughness and lubrication functions is obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings described herein are used to provide further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0021] Figure 1 It is a process flow chart of the present invention;

[0022] Figure 2 It is a schematic diagram of the process of the present invention;

[0023] Figure 3 This is a comparison chart of the average wear rates of the surfaces of the original untreated sample, the laser shock peening sample, the laser shock peening + bionic texturing sample, and the laser shock peening + bionic texturing + ion nitriding sample of the present invention. DETAILED DESCRIPTION

[0024] This section will describe in detail the specific embodiments of the present invention. The preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the text part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the present invention, but it should not be understood as a limitation on the scope of protection of the present invention.

[0025] Reference Figure 1-Figure 3 In a preferred embodiment of the present invention, a method for constructing a tough, lubricating, and wear-resistant layer on the surface of gear steel and a preparation process thereof include the following steps:

[0026] S1. Pre-treating the gear steel sample and its surface, including heat treatment of the gear steel sample and polishing of the gear steel surface;

[0027] S2, using laser shock peening technology to introduce a dislocation strengthening layer on the surface of the gear steel sample after pretreatment;

[0028] S3. Processing bionic micro-textures: Using ultrafast lasers to process bionic micro-textures with lubricating function on the surface of the dislocation strengthening layer;

[0029] S4. Ion nitriding treatment: Ion nitriding treatment is performed on the bionic micro-textured surface to obtain a wear-resistant layer with both toughness and lubrication functions on the surface of the gear steel sample;

[0030] The order of step S3 and step S4 can be swapped, that is, the dislocation strengthening layer is first subjected to ion nitriding treatment and then processed to produce the bionic microtexture.

[0031] Furthermore, in step S1, after the gear steel sample is heat treated, the surface of the gear steel sample is ground using 800# to 2000# grit sandpaper in sequence, and polished using diamond polishing liquid. Finally, the polished gear steel sample is ultrasonically cleaned in an acetone solution for 10 minutes.

[0032] Furthermore, in step S2, the laser uses a nanosecond pulse laser, and the laser shock peening processing conditions are: wavelength 1064nm, pulse width 15~20ns, pulse frequency 1~5Hz, single pulse energy 1~20J, spot diameter 2~3mm, and spot overlap rate 35%~75%; during the laser shock peening process, a 2mm thick flowing water film is used as a constraining layer and a 100μm thick aluminum foil is used as a protective layer.

[0033] Furthermore, in step S3, the ultrafast laser uses a femtosecond laser, and the processing conditions of the femtosecond laser are: single pulse energy 0-5mJ, maximum repetition frequency 100kHz, central wavelength 1035nm, pulse width 300fs, focused spot diameter 15-25μm, processing speed 0.1-6000mm / s; high-precision processing motion platform, X / Y / Z axis positioning accuracy ±1μm, A / B axis positioning accuracy ±3arc / s.

[0034] Preferably, the high-precision processing motion platform is a femtosecond laser processing device, specifically a high-energy fiber femtosecond laser of model Femto-IR-1000-100.

[0035] Furthermore, the bionic microtexture processed in step S3 is a natural biological surface structure with lubricating function, and the natural biological surface structures include marine shellfish texture, cricket foot pad structure, shark skin surface shield scale structure, lotus surface papilla structure, Nepenthes pitcher surface crescent structure, dung beetle body surface pit-shaped structure, and lizard scale structure.

[0036] Furthermore, the nitriding conditions of the ion nitriding in step S4 are: nitriding temperature 350-550°C, nitriding gas is a mixture of nitrogen and argon, the volume ratio of nitrogen to argon is 1:2, nitriding pressure is 0-350 Pa, nitriding treatment time is 5-12 h, and nitriding voltage is 100-1000 V.

[0037] Furthermore, the ion nitriding treatment in step S4 can be replaced by one of carburizing, carbonitriding, boronizing, sulfurizing, metallizing, and multi-element co-nitriding treatments.

[0038] Example 1

[0039] like Figure 1 As shown in FIG, a method for constructing a tough, lubricating, and wear-resistant layer on the surface of gear steel provided by the present invention and a flow chart of its preparation process, comprising the following steps:

[0040] S1. Heat treat 15Cr14Co12Mo5Ni2WA stainless steel using the following process: 1065°C for 1 hour, oil cooling; -85°C for 2 hours, 500°C for 2 hours, air cooling; 85°C for 2 hours, 500°C for 2 hours, air cooling. After heat treatment, the surface is ground using 800# to 2000# grit sandpaper and polished using diamond polishing fluid. Finally, the polished sample is ultrasonically cleaned in acetone for 10 minutes.

[0041] S2. The above samples were strengthened using nanosecond laser shock peening (NLSP). The laser shock peening process parameters were: laser wavelength 1064 nm, pulse width 15 ns, pulse frequency 2 Hz, single pulse energy 10 J, spot diameter 2 mm, and spot overlap ratio 50%. During the NLSP process, a 2 mm thick flowing water film was used as the constraining layer, and a 100 μm thick aluminum foil was used as the protective layer.

[0042] like Figure 2 As shown, 1 is the laser spot, 2 is the pitcher plant crescent bionic texture, 3 is the injected ions, D is the laser spot diameter, R is the outer diameter of the bionic texture contour, r is the inner diameter of the bionic texture contour, H is the height of the bionic texture contour, S is the longitudinal distance between adjacent bionic textures, and L is the lateral distance between adjacent bionic textures.

[0043] S3. A femtosecond laser was used to perform bionic texture processing on the surface of the sample after laser shock strengthening. The bionic texture was the crescent structure 2 of the pitcher plant. The femtosecond laser processing parameters of a single crescent structure were: single pulse energy 0.02 mJ, repetition rate 100 kHz, central wavelength 1035 nm, pulse width 300 fs, focused spot diameter 15 μm, processing speed 1000 mm / s, scanning line spacing 5 μm, and number of scans 25 times; the high-precision processing motion platform parameters were: X / Y / Z axis positioning accuracy ±1 μm, A / B axis positioning accuracy ±3 arc / s; the crescent structure parameters were: outer diameter R was 0.3 mm, inner diameter r was 0.2 mm, height H was 0.3, depth was approximately 30 μm, and spacing S was 0.3 mm.

[0044] S4. The bionic micro-textured surface is subjected to low-temperature ion nitriding. The process parameters of the low-temperature ion nitriding are as follows: nitriding temperature 450°C, nitriding gas is a mixture of nitrogen and argon with a volume ratio of 1:2, nitriding pressure 60Pa, nitriding treatment time 8h, and nitriding voltage 850V.

[0045] The present invention induces a high-density dislocation toughening layer through laser shock, and utilizes the promoting effect of high-density dislocation to perform ion nitriding toughening treatment; then, by preparing a bionic texture on the surface of the high-density dislocation layer and utilizing the super-lubricity effect of the bionic texture, the toughened surface is made to have super-lubricity.

[0046] Under the premise that no conflict occurs, those skilled in the art may freely combine and superimpose the above-mentioned additional technical features.

[0047] The above descriptions are only preferred embodiments of the present invention. Any technical solution that achieves the purpose of the present invention by substantially the same means shall fall within the scope of protection of the present invention.

Claims

1. A method for constructing a tough, lubricating, and wear-resistant layer on the surface of gear steel and its preparation process, characterized by: The specific steps include: S1. Pre-treating the gear steel sample and its surface, including heat treatment of the gear steel sample and polishing of the gear steel surface; S2, using laser shock peening technology to introduce a dislocation strengthening layer on the surface of the gear steel sample after pretreatment; S3. Processing bionic micro-textures: Using ultrafast lasers to process bionic micro-textures with lubricating function on the surface of the dislocation strengthening layer; S4. Ion nitriding treatment: Ion nitriding treatment is performed on the bionic micro-textured surface to obtain a wear-resistant layer with both toughness and lubrication functions on the surface of the gear steel sample; The order of step S3 and step S4 can be swapped, that is, the dislocation strengthening layer is first subjected to ion nitriding treatment and then processed to produce the bionic microtexture.

2. The method for constructing a tough, lubricating, and wear-resistant layer on the surface of gear steel according to claim 1 and its preparation process are characterized by: In step S1, after the gear steel sample is heat treated, the surface of the gear steel sample is ground with 800# to 2000# grit sandpaper in sequence, and polished with diamond polishing liquid. Finally, the polished gear steel sample is ultrasonically cleaned in acetone solution for 10 minutes.

3. The method for constructing a tough, lubricating, and wear-resistant layer on the surface of gear steel according to claim 1 and its preparation process are characterized by: In step S2, the laser uses a nanosecond pulse laser, and the laser shock peening processing conditions are: wavelength 1064nm, pulse width 15~20ns, pulse frequency 1~5Hz, single pulse energy 1~20J, spot diameter 2~3mm, and spot overlap rate 35%~75%; during the laser shock peening process, a 2mm thick flowing water film is used as a constraining layer and a 100μm thick aluminum foil is used as a protective layer.

4. The method for constructing a tough, lubricating, and wear-resistant layer on the surface of gear steel according to claim 1 and its preparation process are characterized by: In step S3, the ultrafast laser uses a femtosecond laser, and the processing conditions of the femtosecond laser are: single pulse energy 0-5mJ, maximum repetition frequency 100kHz, central wavelength 1035nm, pulse width 300fs, focused spot diameter 15-25μm, processing speed 0.1-6000mm / s; high-precision processing motion platform, X / Y / Z axis positioning accuracy ±1μm, A / B axis positioning accuracy ±3arc / s.

5. The method for constructing a tough, lubricating, and wear-resistant layer on the surface of gear steel according to claim 1 and its preparation process are characterized by: The bionic microtexture processed in step S3 is a natural biological surface structure with a lubricating function, and the natural biological surface structures include the texture of marine shellfish, the structure of cricket foot pads, the shield scale structure of shark skin surface, the papilla structure of lotus surface, the crescent structure of pitcher plant pitcher surface, the pit-shaped structure of dung beetle body surface, and the scale structure of lizard.

6. The method for constructing a tough, lubricating, and wear-resistant layer on the surface of gear steel according to claim 1 and its preparation process, characterized in that: The nitriding conditions of the ion nitriding in step S4 are: nitriding temperature 350-550°C, nitriding gas is a mixture of nitrogen and argon, the volume ratio of nitrogen to argon is 1:2, nitriding pressure is 0-350 Pa, nitriding treatment time is 5-12 h, and nitriding voltage is 100-1000 V.

7. The method for constructing a tough, lubricating, and wear-resistant layer on the surface of gear steel according to claim 1 and its preparation process, characterized in that: The ion nitriding treatment in step S4 can be replaced by one of carburizing, carbonitriding, boronizing, sulfurizing, metallizing, and multi-element co-nitriding treatments.

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