A surface treatment method for improving the wear resistance of a metal substrate under oil-free lubrication

Abstract

The application discloses a surface treatment method for improving wear resistance of a metal matrix under oil-free lubrication, and compositely textured surfaces of the metal matrix are processed, wherein the compositely textured surfaces are composed of a plurality of hexagonal units arranged in a honeycomb shape, grooves are arranged between any adjacent hexagonal units, and a circular groove is arranged in the middle of each hexagonal unit; and a responsive multi-element composite solid lubricant is filled in the grooves and the circular groove between any adjacent hexagonal units; wherein the responsive multi-element composite solid lubricant is a composite of tin, carbon nanotubes, multi-element two-dimensional materials and NiTi alloy powder. The surface treatment method makes the metal matrix have excellent load-carrying capacity and self-lubricating performance under oil-free lubrication, and can solve the problem of high wear resistance of the existing metal matrix under oil-free lubrication.

Description

Technical Field

[0001] This invention relates to the field of metal material surface treatment technology, and specifically to a surface preparation method for improving the wear resistance of a metal substrate under oil-deficient lubrication. Background Technology

[0002] With the rapid development of high-end equipment in aerospace, transportation, and energy fields, the working environment of their friction pairs is becoming increasingly demanding, requiring breakthroughs in numerous technical bottlenecks such as environmental adaptability and performance stability. In actual service, high-end equipment such as bearings and gear pairs often face the problem of insufficient lubrication, indirect friction, and special operating conditions leading to ineffective lubrication—a phenomenon known as "oil-deficient lubrication"—which significantly impacts energy consumption, material consumption, and equipment reliability. Improving the wear resistance of metal substrates under oil-deficient lubrication is crucial for enhancing the service performance of high-end equipment. Generally, surface treatment technologies for improving the wear resistance of metal substrates under oil-deficient lubrication can be broadly categorized into surface strengthening, surface modification, and lubrication system design. In recent years, composite technologies for improving the wear resistance of metal substrates under oil-deficient lubrication have attracted attention, such as micro-arc oxidation and coatings, thermal oxidation and laser surface texturing, and surface texturing combined with solid lubricants.

[0003] Currently, in composite technologies involving surface texture and solid lubricants, the solid lubricants are primarily soft metals. While this composite technology improves the tribological properties of the metal matrix under general lubrication conditions to some extent, it still suffers from severe lubricant loss in the textured areas and ineffective lubrication in localized areas, leading to pitting on the contact surface. Especially under oil-deficient lubrication, the contact interface faces temperature increases and significant impact loads in localized areas during the transition from oil lubrication to oil-deficient lubrication, severely impacting the lubricant's adsorption, lubrication, and load-bearing properties with the metal matrix. Therefore, how to reduce the tribological properties of metal substrate surfaces under oil-deficient lubrication through surface texture composite responsive lubricants is of particular importance. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a surface treatment method to improve the wear resistance of metal substrates under oil-deficient lubrication, thereby addressing the shortcomings of the prior art. This method enables the metal substrate to have excellent load-bearing capacity and self-lubricating properties under oil-deficient lubrication, and can solve the problem of low wear resistance of existing metal substrates under oil-deficient lubrication.

[0005] The technical solution adopted by the present invention to solve the above-mentioned problems is as follows:

[0006] A surface treatment method for improving the wear resistance of a metal substrate under oil-deficient lubrication involves processing a composite texture on the surface of the metal substrate. The composite texture consists of multiple hexagonal units arranged in a honeycomb pattern, with grooves formed between any adjacent hexagonal units and a circular groove formed in the center of each hexagonal unit. A responsive multi-component composite solid lubricant is then used to fill the grooves and circular grooves between any adjacent hexagonal units. The responsive multi-component composite solid lubricant is a composite of tin, carbon nanotubes, multi-component two-dimensional materials, and NiTi alloy powder.

[0007] According to the above scheme, the surface area of ​​the responsive multi-component solid lubricant filling area accounts for 20%-40% of the total surface area of ​​the substrate. The diameter of the circumscribed circle of each hexagonal unit is 1000-2000μm, the groove width is 200-300μm, and the radius of the circular groove is 50-400μm. The depth of the groove and the circular groove are consistent, with a depth range of 30-60μm.

[0008] According to the above scheme, the raw materials in the responsive composite multi-element solid lubricant include, by mass percentage: 70-80 wt.% tin powder, 10-15 wt.% carbon nanotubes, 6-12 wt.% multi-element two-dimensional materials, and 3-5 wt.% NiTi alloy powder.

[0009] According to the above scheme, the tin powder in the composite solid lubricant has a particle size range of 50-65μm and a purity of over 99%; the carbon nanotubes have a diameter range of 10-50nm and a purity of over 95%; and the NiTi alloy powder has a particle size range of 15-53μm and a purity of over 95%.

[0010] According to the above scheme, the multi-element two-dimensional material is prepared by coating a mixture of ammonium tungstate, molybdenum, titanium, boron, and carbon onto a molybdenum wire as a carrier, followed by high-temperature reaction synthesis in an argon-enhanced atmosphere containing tetrabutyl titanate. The mixture comprises, by mass percentage: ammonium tungstate 15-25 wt.%, molybdenum 15-25 wt.%, titanium 10-18 wt.%, boron 8-15 wt.%, and carbon 30-38 wt.%. Further, the specific steps of the preparation method of the multi-element two-dimensional material are as follows:

[0011] 1) Mixing: Mix the powdered raw materials according to the mass percentage, wherein each raw material is 15-25 wt.% ammonium tungstate, 15-25 wt.% molybdenum, 10-18 wt.% titanium, 8-15 wt.% boron and 30-38 wt.% carbon, and the mixture is obtained by vibrating mixer;

[0012] 2) Sintering: Add water to the mixture to make a viscous paste, coat it evenly on the molybdenum wire, and sinter it in a molybdenum wire furnace under an argon atmosphere. The argon gas flow rate is 60-100 mL / min, and the argon gas flows through the tetrabutyl titanate into the molybdenum wire furnace. The sintering temperature is 800-1000℃, and the holding time is 60-80 min. After the holding time is completed, a multi-element two-dimensional material is formed on the surface of the molybdenum wire, which is scraped off for later use.

[0013] Furthermore, the above-mentioned surface treatment method for improving the wear resistance of metal substrates under oil-deficient lubrication mainly includes the following steps:

[0014] (1) Polish the surface of the metal substrate to make its surface roughness less than 0.02μm, then clean and dry it;

[0015] (2) Use a laser marking machine to process a preset composite texture on the surface of the metal substrate, then immerse it in a zinc chloride solution to remove the oxide layer (zinc chloride can dissolve metal oxides), and dry it after cleaning; this step helps to improve the bonding between the responsive multi-component solid lubricant and the metal substrate;

[0016] (3) The responsive multi-component solid lubricant is filled into the grooves and circular grooves of the composite texture using vacuum melting and infiltration technology. After polishing again to make the surface roughness about 0.01μm, a metal matrix suitable for oil-deficient lubrication is obtained.

[0017] In this invention, the metal substrate is mainly alloy structural steel, such as 20CrMnTi, 40Cr, and 42CrMo. This invention uses 42CrMo alloy steel as an example, but is not limited to this substrate. Before processing the composite texture on the metal substrate surface, polishing and cleaning are performed until the surface roughness is less than 0.02μm, followed by cleaning and drying.

[0018] In this invention, lubrication without lubricating oil specifically includes scenarios where, during the start / stop operation of mechanical moving parts, the upper surface of the mechanical parts is subjected to dry friction or intermittent lubrication under the action of gravity, and there is no lubrication for a short period of time.

[0019] According to the above scheme, the vacuum infiltration method is as follows: the responsive multi-component solid lubricant and the metal matrix are placed on a crucible and a fixed support respectively in a vacuum pressure infiltration furnace, and a vacuum is drawn to 0.1-0.2×10⁻⁶. -2 The heating temperature is 600-800℃, and after holding at that temperature for 120-150 minutes, the solid lubricant is melted and penetrated into the grooves and circular recesses of the composite texture of the metal matrix. At the same time, the gas pressure is increased to 1.5-2.0MPa, and the melting and penetration time is 60-90 minutes. The furnace is then cooled to room temperature.

[0020] According to the above scheme, the processing of composite textures on the surface of metal substrate can be achieved by using a laser marking machine. The laser marking power is 18-27W, the number of scans is 20-60, and the laser scanning speed is 1600-3000mm / s.

[0021] This invention controls the load-bearing capacity of a metal matrix by designing the shape and geometric parameters of the surface texture, and improves the lubrication performance of metal matrix composites by modifying solid lubricants, effectively solving the problem of achieving a balance between the load-bearing capacity and lubrication capacity of a metal matrix surface. The specific technical concept of this invention is as follows:

[0022] The fundamental reason for the poor tribological performance of metal-to-metal interfaces under oil-deficient lubrication is insufficient oil lubrication or the inability of the lubricating oil to function effectively. This invention utilizes a surface-textured, melt-penetrating, responsive multi-component solid lubricant to prepare a composite surface that can reduce friction and wear on the metal substrate surface through solid lubrication when lubricating oil is ineffective. However, excessively high texture density on the metal substrate surface will reduce the load-bearing capacity of the contact interface; conversely, insufficient texture density will prevent the filled responsive multi-component solid lubricant from effectively performing its lubricating function.

[0023] This invention utilizes a composite texture combined with a responsive multi-component solid lubricant under oil-deficient lubrication conditions. The surface texture adopts a composite texture form of hexagonal grooves nested with circular grooves, with a texture density in the range of 20-40%.

[0024] The responsive multi-component composite solid lubricant with surface texture filling described in this invention plays a key role in solid lubrication under oil-deficient lubrication conditions. This responsive multi-component composite solid lubricant consists of a base phase, a reinforcing phase, and a responsive phase. Tin is the base phase of the solid lubricant; carbon nanotubes and multi-component two-dimensional materials are the reinforcing phases, which can improve the adsorption and lubrication of the base phase at the contact interface. Furthermore, carbon nanotubes, being 2D additives, can effectively reduce the coefficient of friction; the multi-component two-dimensional materials not only improve the lubrication performance of the solid lubricant but also enhance its adsorption to the substrate surface, reducing the shedding of the solid lubricant from the substrate. Additionally, NiTi alloy is the responsive phase. During the transition from oil lubrication to oil-deficient lubrication, the contact interface faces a temperature increase. As a smart lubricating material, NiTi alloy actively expands upon reaching the temperature transition point, allowing the solid lubricant to spread across the contact interface and form a lubricating film, thereby reducing wear on the metal substrate.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] 1. The metal substrate obtained by the surface treatment method of this invention has excellent friction reduction and wear resistance. The friction coefficient and wear rate under oil-deficient lubrication are significantly reduced, which can solve the problems of high friction coefficient and high wear rate of metal substrate surface under oil-deficient lubrication.

[0027] 2. The metal substrate surface obtained by this method of the present invention has a composite texture and a responsive multi-component composite solid lubricant. When the temperature at the contact interface rises significantly, the NiTi alloy will gradually expand automatically when the temperature reaches the response point, causing the solid lubricant to spread on the contact interface. In addition, the mutual compression of the interface will also cause the solid lubricant to spread to the contact interface to form a transfer film, thereby avoiding direct contact between the friction pairs and playing a wear-resistant role. Attached Figure Description

[0028] Figure 1 This is a morphology diagram of the multi-element two-dimensional material in Example 1;

[0029] Figure 2 This is a morphology diagram of the carbon nanotubes in Example 3;

[0030] Figure 3 These are morphology images of the composite texture prepared in Example 2 (where the black area is the filling area of ​​the responsive multi-component solid lubricant) and the final obtained metal substrate surface.

[0031] Figure 4 It is the average coefficient of friction of the samples prepared in Examples 1, 2 and 3 under oil-deficient lubrication;

[0032] Figure 5 The instantaneous friction coefficient of 42CrMo alloy steel and the 42CrMo alloy steel matrix obtained by the surface treatment method in Example 3 under oil-depleted lubrication. Detailed Implementation

[0033] The present invention will be further described in detail below with reference to specific embodiments, but the present invention is not limited to the following specific embodiments.

[0034] In the following embodiments, the tin powder has a particle size range of 50-65 μm and a purity of over 99%; the carbon nanotubes have a diameter range of 10-50 nm and a purity of over 95%; and the NiTi alloy powder has a particle size range of 15-53 μm and a purity of over 95%.

[0035] Example 1

[0036] A surface treatment method for improving the wear resistance of a metal substrate under oil-deficient lubrication includes the following steps:

[0037] Step 1: Grind and polish the surface of the 42CrMo alloy steel to make its surface roughness less than 0.02μm. Then, clean it with anhydrous ethanol using ultrasound for 5 minutes. After cleaning, dry it for use in Step 2.

[0038] Step 2: Use a 30W laser marking machine to mark the surface of 42CrMo alloy steel according to the parameters of the composite texture. The power is 18W, the number of scans is 60, and the laser scanning speed is 2800mm / s. The composite texture consists of multiple regular hexagonal units arranged in a honeycomb pattern. Grooves are opened between any adjacent regular hexagonal units, and a circular groove is opened in the center of each regular hexagonal unit. The grooves and circular grooves between any adjacent regular hexagonal units are filled with a responsive multi-component composite solid lubricant. The total area of ​​the grooves and circular grooves accounts for 20% of the total area of ​​the substrate surface. The circumscribed circle diameter of each hexagonal unit is 1600μm, the groove width is 250μm, and the radius of the circular groove is 50μm. The distance between the centers of two adjacent circular grooves is 1545μm. The depth of the hexagonal grooves and circular grooves is consistent, with a depth range of 50μm.

[0039] Step 3: Immerse the 42CrMo alloy steel obtained in Step 2 in zinc chloride solution for 3 minutes, then rinse the substrate surface with deionized water and dry it to remove the oxide layer and impurities on the surface.

[0040] Step 4: Place the responsive multi-component solid lubricant and the metal matrix obtained in Step 3 on the crucible and fixed support respectively in a vacuum pressure melting furnace, and evacuate to 0.12 × 10⁻⁶. -2 The furnace is heated to 650℃ and held for 140 min to allow the responsive multi-component solid lubricant to melt into the grooves and circular recesses of the composite texture of the metal matrix (although a small amount of responsive multi-component solid lubricant will also melt into the non-groove and non-circular recess areas during operation, the final polishing step will expose the 42CrMo alloy steel itself in the non-filled areas). Simultaneously, the gas pressure is increased to 1.6 MPa, and the melting time is 85 min. The furnace is then cooled to room temperature, followed by polishing to achieve a surface roughness of 0.01 μm, resulting in a metal matrix suitable for oil-deficient lubrication.

[0041] In this embodiment, the responsive multi-component composite solid lubricant is composed of 75 wt.% tin powder, 12 wt.% carbon nanotubes, 10 wt.% multi-component two-dimensional material, and 3 wt.% NiTi alloy powder by mass percentage. The preparation method of the multi-component two-dimensional material is as follows: 24 wt.% ammonium tungstate, 20 wt.% molybdenum, 16 wt.% titanium, 10 wt.% boron, and 30 wt.% carbon powders are mixed using a vibratory mixer, and deionized water is added to form a viscous paste. This paste is then uniformly coated onto a molybdenum wire and transferred to a molybdenum wire furnace. Argon gas is first introduced at a rate of 70 mL / min (the argon gas enters the molybdenum wire furnace via a volumetric flask containing tetrabutyl titanate). Subsequently, sintering is performed in the molybdenum wire furnace at a temperature of 950°C for 65 min to obtain the multi-component two-dimensional material, as shown below. Figure 1 As shown, this multi-element two-dimensional material has a layered structure, which facilitates interlayer slippage and thus reduces friction.

[0042] To simulate oil-deficient lubrication conditions, a metal substrate suitable for oil-deficient lubrication, prepared using the surface treatment method described in Example 1, was cut into several test blocks. These blocks were immersed in lubricating oil for 30 minutes, and then left to stand for 30 minutes. No additional lubricating oil was added during the test. Untreated 42CrMo alloy steel was used as a control sample.

[0043] The above test block underwent an oil-deficient lubrication test at a sliding speed of 20 N and 1 Hz, with each friction cycle lasting 1800 s, and the test was repeated three times with the average value taken. In the oil-deficient friction test between the GCr15 grinding ball and the metal substrate surface, the wear rate of the test block surface in Example 1 was 2.1 × 10⁻⁶. -8 cm 3 The friction coefficient is 0.13, with a strength of / (N·m), indicating good friction reduction and wear resistance. In contrast, the control sample's test block had a friction coefficient of 0.18 and a wear rate of 3.8 × 10⁻⁶ N·m. -7 cm 3 / (N·m), with obvious scratches on the surface.

[0044] Example 2

[0045] A surface treatment method for improving the wear resistance of a metal substrate under oil-deficient lubrication includes the following steps:

[0046] Step 1: Grind and polish the surface of the 42CrMo alloy steel to make its surface roughness less than 0.02μm. Then, clean it with anhydrous ethanol using ultrasound for 8 minutes. After cleaning, dry it for use in Step 2.

[0047] Step 2: Use a 30W laser marking machine to mark the surface of 42CrMo alloy steel according to the parameters of the composite texture. The power is 24W, the number of scans is 40, and the laser scanning speed is 2000mm / s. The composite texture consists of multiple regular hexagonal units arranged in a honeycomb pattern. Grooves are opened between any adjacent regular hexagonal units, and a circular groove is opened in the center of each regular hexagonal unit. A responsive multi-component composite solid lubricant is used to fill the grooves and circular grooves between any adjacent regular hexagonal units. The total area of ​​the grooves and circular grooves accounts for 30% of the total area of ​​the substrate surface. The circumscribed circle diameter of each hexagonal unit is 1600μm, the groove width is 250μm, and the radius of the circular groove is 261μm. The distance between the centers of two adjacent circular grooves is 1545μm. The depth of the hexagonal grooves and circular grooves is consistent, with a depth range of 50μm.

[0048] Step 3: Immerse the 42CrMo alloy steel obtained in Step 2 in zinc chloride solution for 4 minutes, then rinse the substrate surface with deionized water and dry it to remove the oxide layer and impurities on the surface and improve the adhesion between the lubricant and the metal substrate.

[0049] Step 4: Place the responsive multi-component solid lubricant and the metal matrix obtained in Step 3 on the crucible and fixed support respectively in a vacuum pressure melting furnace, and evacuate to 0.16 × 10⁻⁶. -2 The furnace was heated to 700℃ and held for 130 min to allow the responsive multi-component solid lubricant to melt and penetrate into the grooves and circular recesses of the composite texture of the metal substrate. Simultaneously, the gas pressure was increased to 1.8 MPa, and the melting and penetration time was 70 min. The substrate was then cooled to room temperature in the furnace, followed by polishing to achieve a surface roughness of 0.01 μm, resulting in a metal substrate suitable for oil-deficient lubrication.

[0050] In this embodiment, the responsive multi-component composite solid lubricant is composed of 74 wt.% tin powder, 10 wt.% carbon nanotubes, 12 wt.% multi-component two-dimensional material, and 4 wt.% NiTi alloy powder by mass percentage. The preparation method of the multi-component two-dimensional material is as follows: 18 wt.% ammonium tungstate, 23 wt.% molybdenum, 18 wt.% titanium, 8 wt.% boron, and 33 wt.% carbon powders are mixed using a vibratory mixer, and deionized water is added to form a viscous paste. This paste is then uniformly coated onto a molybdenum wire and transferred to a molybdenum wire furnace. Argon gas at a flow rate of 80 mL / min is introduced (the argon gas enters the molybdenum wire furnace via a volumetric flask containing tetrabutyl titanate). Sintering is then performed in the molybdenum wire furnace at a temperature of 900°C for 90 min to obtain the multi-component two-dimensional material.

[0051] To simulate oil-deficient lubrication conditions, a metal substrate suitable for oil-deficient lubrication, prepared using the surface treatment method of Example 2, was cut into several test blocks. These blocks were immersed in lubricating oil for 30 minutes, and then left to stand for 20 minutes. No additional lubricating oil was added during the test. Untreated 42CrMo alloy steel was used as a control sample.

[0052] The above test block underwent an oil-deficient lubrication test at a sliding speed of 20 N and 1 Hz, with each friction cycle lasting 1800 s, and the experiment was repeated three times with the average value taken. In the oil-deficient friction test between the GCr15 grinding ball and the metal substrate surface, the wear rate of the test block surface in Example 2 was 3.2 × 10⁻⁶. -8 cm 3 The friction coefficient is 0.15, with a strength of / (N·m), indicating good friction reduction and wear resistance. In contrast, the control sample's test block had a friction coefficient of 0.22 and a wear rate of 4.4 × 10⁻⁶ N·m. -7 cm 3 / (N·m), with obvious scratches on the surface.

[0053] Example 3

[0054] A surface treatment method for improving the wear resistance of a metal substrate under oil-deficient lubrication includes the following steps:

[0055] Step 1: Grind and polish the surface of the 42CrMo alloy steel to make its surface roughness less than 0.02μm. Then, clean it with anhydrous ethanol using ultrasound for 10 minutes. After cleaning, dry it for use in Step 2.

[0056] Step 2: Use a 30W laser marking machine to mark the surface of 42CrMo alloy steel according to the parameters of the composite texture. The power is 27W, the number of scans is 25, and the laser scanning speed is 1800mm / s. The composite texture consists of multiple regular hexagonal units arranged in a honeycomb pattern. Grooves are formed between any adjacent regular hexagonal units, and a circular groove is formed in the center of each regular hexagonal unit. A responsive multi-component composite solid lubricant is used to fill the grooves and circular grooves between any adjacent regular hexagonal units. The total area of ​​the grooves and circular grooves accounts for 40% of the total surface area of ​​the substrate. The circumscribed circle diameter of each hexagonal unit is 1600μm, the groove width is 250μm, and the radius of the circular groove is 366μm. The distance between the centers of two adjacent circular grooves is 1545μm. The depth of the hexagonal grooves and circular grooves is consistent, with a depth range of 50μm.

[0057] Step 3: Immerse the 42CrMo alloy steel obtained in Step 2 in zinc chloride solution for 5 minutes, then rinse the substrate surface with deionized water and dry it.

[0058] Step 4: Place the responsive multi-component solid lubricant and the metal matrix obtained in Step 3 on the crucible and fixed support respectively in a vacuum pressure melting furnace, and evacuate to 0.18 × 10⁻⁶. -2 The furnace was heated to 750℃ and held for 110 min to allow the responsive multi-component solid lubricant to melt and penetrate into the grooves and circular recesses of the composite texture of the metal substrate. Simultaneously, the gas pressure was increased to 2.0 MPa, and the melting and penetration time was 65 min. The substrate was then cooled to room temperature in the furnace, followed by polishing to achieve a surface roughness of 0.01 μm, resulting in a metal substrate suitable for oil-deficient lubrication.

[0059] In this embodiment, the responsive multi-component composite solid lubricant is composed of 73 wt.% tin powder, 14 wt.% carbon nanotubes, 8 wt.% multi-component two-dimensional material, and 5 wt.% NiTi alloy powder by mass percentage. The preparation method of the multi-component two-dimensional material is as follows: 20 wt.% ammonium tungstate, 18 wt.% molybdenum, 15 wt.% titanium, 12 wt.% boron, and 35 wt.% carbon powders are mixed using a vibratory mixer, and deionized water is added to form a viscous paste. This paste is then uniformly coated onto a molybdenum wire and transferred to a molybdenum wire furnace. Argon gas is first introduced at a rate of 100 mL / min (the argon gas enters the molybdenum wire furnace via a volumetric flask containing tetrabutyl titanate). Subsequently, sintering is performed in the molybdenum wire furnace at a temperature of 850°C for 80 min to obtain the multi-component two-dimensional material.

[0060] To simulate oil-deficient lubrication conditions, a metal substrate suitable for oil-deficient lubrication, prepared using the surface treatment method described in Example 3, was cut into several test blocks. These blocks were immersed in lubricating oil for 30 minutes, and then left to stand for 10 minutes. No additional lubricating oil was added during the test. Untreated 42CrMo alloy steel was used as a control sample.

[0061] The above-mentioned test block underwent an oil-deficient lubrication test at a sliding speed of 20 N and 1 Hz, with each friction cycle lasting 1800 s, and the experiment was repeated three times with the average value taken. In the oil-deficient friction test between the GCr15 grinding ball and the metal substrate surface, the wear rate of the test block surface in Example 3 was 1.4 × 10⁻⁶. -8 cm 3 The friction coefficient is 0.10, with a strength of / (N·m), indicating good friction reduction and wear resistance. In contrast, the control sample's test block had a friction coefficient of 0.12 and a wear rate of 2.7 × 10⁻⁶ N·m. -7 cm 3 / (N·m), with obvious scratches on the surface.

[0062] Clearly, the wear resistance of the metal substrate prepared by the surface treatment method of this invention is significantly improved in the case of oil-exhausted lubrication. In the oil-exhausted friction test between a spherical surface and a flat surface, with a load of 20 N and reciprocating friction for 30 min, the wear rate of the metal substrate surface is 1.2-3.5 × 10⁻⁶. -8 cm 3 With a sliding friction coefficient of 0.09-0.178 (N·m), it exhibits good friction reduction and wear resistance. Therefore, the metal substrate surface prepared by the surface treatment method of this invention, suitable for oil-deficient lubrication, possesses excellent wear resistance, with significantly lower friction coefficients and wear rates. Its wear resistance under oil-deficient lubrication conditions is significantly superior to that of ordinary alloy steel surfaces.

[0063] The above are merely exemplary embodiments of the present invention and do not constitute any limitation on the scope of protection of the present invention. All technical solutions formed by equivalent exchange or substitution fall within the scope of protection of the present invention.

Claims

1. A surface treatment method for improving the wear resistance of a metal substrate under oil-free lubrication, characterized in that, The method mainly comprises the following steps: (1) polishing the surface of the metal matrix to a roughness of less than 0.02 microns, and then cleaning and drying; (2) using a laser marking machine to process a preset composite texture on the surface of the metal matrix, then soaking in a zinc chloride solution, cleaning and drying; wherein the composite texture is composed of a plurality of hexagonal cells arranged in a honeycomb shape, a groove is formed between any adjacent hexagonal cells, and a circular groove is formed in the middle of each hexagonal cell; (3) filling the response type multi-element composite solid lubricant into the grooves and circular grooves of the composite texture by vacuum infiltration technology, polishing again to a surface roughness of less than 0.02 microns to obtain a metal matrix suitable for oil-free lubrication; wherein the surface area of the filling area accounts for 20-40% of the total surface area of the matrix; The response type composite multi-element solid lubricant comprises, by mass percentage: tin powder 70-80 wt.%, carbon nanotubes 10-15 wt.%, multi-element two-dimensional material 6-12 wt.%, and NiTi alloy powder 3-5 wt.%; wherein the multi-element two-dimensional material is prepared by using molybdenum wire as a carrier, coating a mixture of ammonium tungstate, molybdenum, titanium, boron and carbon, and then synthesizing in an argon enhanced atmosphere containing butyl titanate at high temperature; wherein the mixture comprises, by mass percentage: ammonium tungstate 15-25 wt.%, molybdenum 15-25 wt.%, titanium 10-18 wt.%, boron 8-15 wt.%, and carbon 30-38 wt.%.

2. The surface treatment method for improving the wear resistance of a metal substrate under oil-free lubrication according to claim 1, characterized in that, The depth of the groove and the circular groove is 30-80 microns.

3. The surface treatment method for improving the wear resistance of a metal substrate under oil-free lubrication according to claim 1, characterized in that, The diameter of the circumscribed circle of each hexagonal cell is 1000-2000 microns, the groove spacing is 200-300 microns, and the radius of the circular groove is 50-400 microns.

4. The surface treatment method for improving the wear resistance of a metal substrate under oil-free lubrication according to claim 1, characterized in that, The preparation method of the multi-element two-dimensional material comprises the following steps: 1) mixing: mixing the raw material powders according to the mass percentage, wherein the raw materials are ammonium tungstate 15-25 wt.%, molybdenum 15-25 wt.%, titanium 10-18 wt.%, boron 8-15 wt.%, and carbon 30-38 wt.%, and mixing by a vibration mixer to obtain a mixture; 2) sintering: adding the mixture to water to form a thick paste, uniformly coating the paste on the molybdenum wire, and sintering using a molybdenum wire furnace, with an argon atmosphere, an argon flow rate of 60-100 mL / min, and argon flowing through butyl titanate into the molybdenum wire furnace, a sintering temperature of 800-1000℃, and a holding time of 60-80 min, to form a multi-element two-dimensional material on the surface of the molybdenum wire, which is scraped off for use.

5. The surface treatment method for improving the wear resistance of a metal substrate under oil-free lubrication according to claim 1, characterized in that, The metal matrix is an alloy structural steel.

6. The surface treatment method for improving the wear resistance of a metal substrate under oil-free lubrication according to claim 1, characterized in that, The method of vacuum infiltration is as follows: the responsive multi-element composite solid lubricant and the metal matrix are respectively placed on the crucible and the fixed support in the vacuum pressure infiltration furnace, vacuum is drawn to 0.1-0.2×10 -2 Pa, the heating temperature is 600-800℃, and after holding for 120-150min, the solid lubricant is infiltrated into the composite texture groove and circular groove of the metal matrix, at the same time, the air pressure is raised to 1.5-2.0MPa, the infiltration time is 60-90min, and then the furnace is cooled to room temperature.

7. The method of claim 1 wherein the metal substrate is a metal substrate that is to be used in an oil-free environment. The laser marking machine is used to process the composite texture on the surface of the metal matrix, and the laser marking power is 18-27 W, the scanning frequency is 20-60 times, and the scanning speed of the laser is 1600-3000 mm / s.

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