Copper-based wear-resistant coating with three-dimensional network structure and preparation method thereof

Abstract

The invention relates to a copper-based wear-resistant coating with a three-dimensional network structure. The coating is composed of a pure copper bonding layer and a copper-based wear-resistant layer with silver as the three-dimensional network structure. Meanwhile, the invention further discloses a preparation method of the coating, and the coating is obtained by adopting a low-pressure cold spraying technology and carrying out layer-by-layer solid deposition on silver-coated copper spraying powder of the core-shell structure on the surface of a stainless steel substrate with a pure copper bonding layer. The preparation method is simple and efficient, the obtained coating material with the three-dimensional network structure is compact in structure, particle interfaces in the coating are well combined, and a foundation is laid for design, preparation and additive repair of the high-thermal-conductivity, high-electric-conductivity and wear-resistant copper-based coating material with the three-dimensional network structure.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of metal material surface protective coating and additive repair technology, and particularly relates to a three-dimensional network structure copper-based wear-resistant coating and a preparation method thereof. BACKGROUND

[0002] Copper and copper alloy materials are widely used in high-tech fields such as aerospace, electronics and electrical appliances, and rail transportation due to their excellent thermal conductivity, electrical conductivity and tribological properties. However, with the increasing complexity and diversity of the service environment of high-end equipment, existing copper-based coating materials are difficult to meet the wear and lubrication requirements of equipment in complex working conditions. Therefore, the design, preparation and application of high-conductivity, high-thermal-conductivity and wear-resistant copper-based coating materials are of great significance to solve the friction and wear problems of high-end equipment in complex working conditions.

[0003] At present, copper-based coating materials are mostly added with zero-dimensional ceramics, cermet and hard metal particles and solid lubricant powders to realize the component, structure design and tribological property improvement of copper-based wear-resistant materials. However, the weak interface bonding and stress concentration between zero-dimensional hard particles and lubricant powders and the copper matrix often have adverse effects on the mechanical and tribological properties of the composite material; and the three-dimensional network structure design can realize the rapid transmission of stress and strain due to its interpenetrating interface structure, which effectively reduces the influence of local stress concentration on the comprehensive performance of the composite material, and has become one of the effective ways to realize the coordinated improvement of the comprehensive performance of high-performance copper-based coating materials.

[0004] Patent CN114540661 A discloses a graphene-reinforced copper-molybdenum composite material with a three-dimensional network structure and a preparation method, which prepares a graphene-reinforced copper-molybdenum composite material by hot-pressing sintering technology through in-situ reduction of copper, molybdenum and graphene oxide composite powders; this method realizes the uniform distribution of graphene in the copper-molybdenum composite material, and improves the strength and toughness of the composite material. However, the current powder metallurgy, thermal spraying and laser cladding and other copper-based wear-resistant coating preparation technologies have problems such as high preparation temperature, easy segregation of metal elements and difficulty in designing three-dimensional network structure inside the coating. Therefore, the design and preparation of new three-dimensional network structure copper-based wear-resistant coating materials are still the research focus and difficulty in the field of high-performance copper-based wear-resistant coating materials. SUMMARY

[0005] The technical problem to be solved by the present application is to provide a three-dimensional network structure copper-based wear-resistant coating with good performance.

[0006] Another technical problem to be solved by the present application is to provide a preparation method of the three-dimensional network structure copper-based wear-resistant coating.

[0007] To solve the above problems, the three-dimensional network structure copper-based wear-resistant coating is characterized in that the coating is composed of a pure copper bonding layer and a three-dimensional network structure copper-based wear-resistant layer taking silver as the material.

[0008] The coating is obtained by using a low-pressure cold spraying technology to perform solid-state deposition of core-shell structure silver-coated copper spraying powder on the surface of a stainless steel substrate with a pure copper bonding layer.

[0009] The core-shell structure silver-coated copper spraying powder has a particle size of -300 mesh.

[0010] The core-shell structure silver-coated copper spraying powder is prepared by the following method: (1) surface pretreatment of pure copper powder: 180 g of pure copper powder is sequentially cleaned with anhydrous ethanol, deionized water, a NaOH solution with a concentration of 3 g / 100 mL, a Na2CO3 solution with a concentration of 2.5 g / 200 mL, deionized water, concentrated HCl, and deionized water to remove surface impurities, organic matter, and an oxide layer, and then filtered to obtain pretreated copper powder. (2) preparation of core-shell structure silver-coated copper powder: First, the pretreated copper powder is stirred and ultrasonically dispersed in 200 mL of a polyvinylpyrrolidone (PVP) aqueous solution with a concentration of 1.5-1.8 g / L to obtain a copper powder-PVP mixed liquid. Then, 100 mL of a silver nitrate-ethylenediaminetetraacetic acid (EDTA) mixed solution with a concentration of 0.2-0.3 mol / L is added to the copper powder-PVP mixed liquid and stirred quickly, and then 900 mL of a silver nitrate-ethylenediaminetetraacetic acid (EDTA) mixed solution and 1000 mL of a glucose solution with a concentration of 0.2-0.3 mol / L are simultaneously added to the copper powder-PVP mixed liquid, the addition rate of the two solutions is controlled to be 15-20 mL / min, and silver plating on the surface of the copper powder is performed in an ultrasonic and stirring manner in a water bath at 38-42°C for 2-3 h; after the silver plating is completed, the upper solution is removed to obtain a powder. Finally, the powder is cleaned with a NaOH solution with a concentration of 1.0-2.0 mol / L and deionized water until the solution is colorless, and then filtered; the filtered powder is dried at 60°C to a constant weight to obtain core-shell structure silver-coated copper powder. (3) preparation of core-shell structure silver-coated copper spraying powder: The core-shell structure silver-coated copper powder is sieved after vacuum heat treatment to obtain core-shell structure silver-coated copper spraying powder with a particle size of -300 mesh.

[0011] The pure copper powder in step (1) is a spherical or spherical-like powder prepared by an atomization method, and has a particle size of -325 mesh.

[0012] The condition of vacuum heat treatment in the step ⑥ is that the temperature is 300-400 DEG C, the holding time is 2h, and the heating rate is 10 DEG C / min.

[0013] The preparation method of the three-dimensional network structure copper-based wear-resistant coating as described above comprises the following steps: ① The surface of the stainless steel substrate is sandblasted by using a low-pressure cold spraying device and 100-mesh alumina sand, and the surface of the sandblasted substrate is blown by compressed air to remove the residual alumina particles; ② The -325-mesh pure copper powder is deposited on the surface of the substrate to form a bonding layer by using the low-pressure cold spraying technology, the number of spraying layers is 1, and the deposition thickness is 100-200 microns; ③ The core-shell structure silver-coated copper spraying powder is deposited on the surface of the pure copper bonding layer by using the low-pressure cold spraying technology, and the spraying is continuously repeated for 3-6 layers, and the total deposition thickness is 600-750 microns, so that the silver-containing three-dimensional network structure copper-based wear-resistant coating is obtained.

[0014] The condition of sandblasting in the step ① is that the sandblasting pressure is 0.60-0.70 MPa, the sandblasting angle is about 90 DEG, and the sandblasting distance is 30-35 mm.

[0015] The condition of the low-pressure cold spraying technology in the steps ② and ③ is that a spraying system composed of a low-pressure cold spraying device and a three-dimensional numerical control slide rail is used, compressed air is used as the working gas, the gas pressure is 0.75-0.85 MPa, the spraying gun is controlled by the three-dimensional numerical control slide rail to spray in a plane and repeatedly in an arch-shaped spraying path, the distance between adjacent spraying paths is 1 mm, the spraying moving speed is 25-35 mm / s, the spraying angle is about 90 DEG, the spraying distance is 8-11 mm, and the spraying gas heating temperature is 400 DEG C-500 DEG C.

[0016] Compared with the prior art, the present application has the following advantages: 1. By designing and preparing the core-shell structure silver-coated copper spraying powder and combining the powder solid-state deposition process of the low-pressure cold spraying coating preparation technology, the efficient preparation of the three-dimensional network structure copper-based wear-resistant coating material is realized, and the coating preparation technology is simple and controllable.

[0017] 2. Compared with the existing copper-based wear-resistant coating preparation technology, the present application has the advantages of low spraying temperature, low coating internal stress and low spraying cost. In addition, the coating preparation technology has small thickness limitation, and can be used for additive repair of the equipment wear surface while realizing the preparation of the material surface protective coating.

[0018] 3、Compared with the existing copper-based wear-resistant coating preparation technology, the coating preparation technology disclosed by the application can realize efficient solid-state deposition of core-shell structure spraying powder raw materials, the particle interface in the coating is well combined, the coating structure is dense, and the uniformity and controllability of the three-dimensional network structure in the coating are obvious.

[0019] 4、The three-dimensional network structure copper-based wear-resistant coating disclosed by the application can improve the stress distribution in the coating and the wear resistance of the coating by the three-dimensional network structure of silver while keeping the excellent electric conductivity and thermal conductivity of the copper matrix, and the design and preparation of a new type of copper-based coating material with high thermal conductivity, high electric conductivity and excellent wear resistance are realized. BRIEF DESCRIPTION OF DRAWINGS

[0020] The specific embodiments of the application will be further described in detail below with reference to the accompanying drawings.

[0021] Figure 1 The SEM photos of the cross section (a) and the local enlarged view (b) of the three-dimensional network structure copper-based wear-resistant coating described in Embodiment 2 of the application.

[0022] Figure 2 The friction coefficient (left) and the wear rate (right) of the three-dimensional network structure copper-based wear-resistant coating described in the application under room temperature environment. DETAILED DESCRIPTION

[0023] A three-dimensional network structure copper-based wear-resistant coating, which is composed of a pure copper bonding layer and a copper-based wear-resistant layer with a three-dimensional network structure of silver. The coating is obtained by using low-pressure cold spraying technology to deposit the core-shell structure silver-coated copper spraying powder layer by layer on the surface of a stainless steel substrate with a pure copper bonding layer.

[0024] The particle size of the core-shell structure silver-coated copper spraying powder is-300 mesh. The powder is prepared by the following method: (1) Surface pretreatment of pure copper powder: 180 g of pure copper powder is cleaned with anhydrous ethanol to remove organic matter on the surface of the copper powder, and then cleaned with deionized water to remove residual anhydrous ethanol in the powder; then, 6 g of NaOH and 2.5 g of Na2CO3 are respectively dissolved in 200 mL of water, and the copper powder is cleaned with the two solutions in sequence to further remove organic matter on the surface of the copper powder; subsequently, the copper powder cleaned with the alkaline solution is cleaned with deionized water for 2-3 times, then acid-washed with 6 mL of concentrated hydrochloric acid for 10-20 minutes to remove the oxide layer on the surface of the copper powder, and then cleaned with deionized water for 2-3 times and filtered to obtain the pretreated copper powder.

[0025] The pure copper powder refers to a spherical or spherical-like powder prepared by atomization, and the particle size is-325 mesh.

[0026] (2) Preparation of core-shell structure silver-coated copper powder: First, the pretreated copper powder is stirred and ultrasonically dispersed in 200 mL of a polyvinylpyrrolidone (PVP) aqueous solution with a concentration of 1.5~1.8 g / L to obtain a copper powder-PVP mixed liquid. Then, 100 mL of a 0.2–0.3 mol / L silver nitrate-EDTA mixture was added to the copper powder-PVP mixture and stirred rapidly. Next, 900 mL of the silver nitrate-EDTA mixture and 1000 mL of a 0.2–0.3 mol / L glucose solution were simultaneously added to the copper powder-PVP mixture, with the addition rate of both solutions controlled at 15–20 mL / min. Silver plating was then performed on the copper powder surface in a water bath at 38–42°C with ultrasonication and stirring for 2–3 hours. After silver plating, the upper layer of solution was removed to obtain the powder. Finally, the powder was washed with a NaOH solution with a concentration of 1.0~2.0 mol / L to remove residual EDTA. The powder was then washed with deionized water until the solution was colorless and filtered. The filtered powder was dried at 60℃ to constant weight to obtain core-shell structured silver-coated copper powder.

[0027] (3) Preparation of core-shell structure silver-coated copper spray powder: mainly by using powder vacuum heat treatment process to remove the stress between the coating and the powder substrate and increase the density and adhesion of the coating.

[0028] The core-shell structured silver-coated copper powder was subjected to vacuum heat treatment at a temperature of 300℃~400℃, a holding time of 2 h, and a heating rate of 10℃ / min, followed by sieving to obtain a core-shell structured silver-coated copper spraying powder with a particle size of -300 mesh.

[0029] A method for preparing a three-dimensional mesh structure copper-based wear-resistant coating includes the following steps: ① The stainless steel substrate surface is sandblasted using low-pressure cold spray equipment and ~100 mesh alumina sand. The sandblasting pressure is 0.60~0.70 MPa, the sandblasting angle is ~90°, and the sandblasting distance is 30~35mm. The sandblasted substrate surface is then blown away with compressed air to remove any residual alumina particles.

[0030] ② Low-pressure cold spraying technology is used to deposit a coating bonding layer of -325 mesh pure copper powder on the substrate surface. The number of spraying layers is 1, and the deposition thickness is 100~200 μm.

[0031] Among them, the conditions for low-pressure cold spraying technology refer to the use of a spraying system consisting of low-pressure cold spraying equipment and a three-dimensional CNC slide rail, with compressed air as the working gas and a gas pressure of 0.75~0.85 MPa. The spray gun is controlled by the three-dimensional CNC slide rail to perform planar and repeated spraying in a bow-shaped spraying path. The spacing between adjacent spraying paths is 1 mm, the spraying movement speed is 25~35 mm / s, the spraying angle is ~90°, the spraying distance is 8~11 mm, and the heating temperature of the spraying gas is 400℃~500℃.

[0032] ③ Low-pressure cold spraying technology is used to deposit core-shell structure silver-coated copper spraying powder on the surface of pure copper bonding layer. The spraying is repeated 3 to 6 times, with a total deposition thickness of 600 to 750 μm. After solid deposition and layer-by-layer stacking, the core-shell structure silver-coated copper spraying powder is used to obtain a silver-containing three-dimensional network structure copper-based wear-resistant coating.

[0033] Among them, the conditions for low-pressure cold spraying technology are the same as those in step ②.

[0034] Example 1: A method for preparing a three-dimensional mesh structure copper-based wear-resistant coating, comprising the following steps: ① The stainless steel substrate surface is sandblasted using low-pressure cold spray equipment and ~100 mesh alumina sand. The sandblasting pressure is 0.60~0.70 MPa, the sandblasting angle is ~90°, and the sandblasting distance is 30~35mm. The sandblasted substrate surface is then blown away with compressed air to remove any residual alumina particles.

[0035] ② Low-pressure cold spraying technology is used to deposit a coating bonding layer of -325 mesh pure copper powder on the substrate surface. The number of spraying layers is 1, and the deposition thickness is 100~150 μm.

[0036] The conditions for low-pressure cold spraying technology are as follows: using a DYMET 423 low-pressure cold spraying equipment combined with a three-dimensional CNC slide rail to spray the surface of the sandblasting substrate material in an arc-shaped straight path, with the distance between adjacent spraying paths being 1 mm; the spraying carrier gas is compressed air with a pressure of 0.75~0.85 MPa, a spraying distance of 8 mm, a spraying angle of ~90°, a spraying gas heating temperature of 400℃, and a spraying moving speed of 25~35 mm / s.

[0037] ③ Preparation of core-shell structured silver-coated copper spray powder: (1) Surface pretreatment of pure copper powder: 180 g of -325 mesh atomized copper powder was accurately weighed using an electronic balance. The powder was then cleaned with anhydrous ethanol to remove organic matter from its surface, followed by cleaning with deionized water to remove any remaining anhydrous ethanol. Next, 6 g of NaOH and 2.5 g of Na₂CO₃ were dissolved in 200 mL of water, and these solutions were used to clean the surface of the copper powder, further removing organic matter. The copper powder cleaned with the alkaline solution was then washed 2-3 times with deionized water, followed by acid washing with 6 mL of concentrated hydrochloric acid for 10 minutes to remove the oxide layer. This was repeated 2-3 times with deionized water, and the powder was then filtered to obtain the pretreated copper powder.

[0038] (2) Preparation of core-shell structured silver-coated copper powder: First, the pretreated copper powder is stirred and ultrasonically dispersed in 200 mL of a polyvinylpyrrolidone (PVP) aqueous solution with a concentration of 1.5~1.8 g / L to obtain a copper powder-PVP mixed liquid. Then, 100 mL of a 0.2–0.3 mol / L silver nitrate-EDTA mixture was added to the copper powder-PVP mixture and stirred rapidly. Next, 900 mL of the silver nitrate-EDTA mixture and 1000 mL of a 0.2–0.3 mol / L glucose solution were simultaneously added to the copper powder-PVP mixture, with the addition rate of both solutions controlled at 15–17 mL / min. Silver plating was then performed on the copper powder surface in a 42°C water bath using ultrasonication and stirring for 2 hours. After silver plating, the upper layer of solution was removed to obtain the powder. Finally, the powder was washed with a NaOH solution with a concentration of 1.0~2.0 mol / L to remove residual EDTA. The powder was then washed with deionized water until the solution was colorless and filtered. The filtered powder was dried at 60℃ to constant weight to obtain core-shell structured silver-coated copper powder.

[0039] (3) Preparation of core-shell structured silver-coated copper spray powder: The core-shell structured silver-coated copper powder was subjected to vacuum heat treatment at 300℃ for 2 hours and a heating rate of 10℃ / min, followed by sieving to obtain a core-shell structured silver-coated copper spray powder with a particle size of -300 mesh.

[0040] Low-pressure cold spraying technology is used to deposit core-shell structured silver-coated copper powder onto the surface of a pure copper bonding layer. The coating is repeated for six consecutive layers to obtain a silver-containing three-dimensional mesh structure copper-based wear-resistant coating.

[0041] Among them, the conditions for low-pressure cold spraying technology are the same as those in step ②.

[0042] The resulting three-dimensional mesh structure copper-based wear-resistant coating has a uniform surface and good interfacial bonding between the coating and the substrate; the average deposition thickness of the coating is about 600 μm.

[0043] The obtained coating was subjected to tribological property testing on a high-speed reciprocating friction and wear testing machine. The test conditions were: friction pair was GCr15 bearing steel balls (Φ6 mm), load 5 N, reciprocating sliding radius 5 mm, sliding speed 5 cm / s, and friction time 30 minutes. The coating wear rate was calculated by measuring the wear volume of the coating using a probe-type tribometer. The results are as follows: Figure 2 As shown, the average coefficient of friction and wear rate of the coating are 0.56 and (1.18±0.18)×10, respectively. - 4 mm 3 / N·m.

[0044] Example 2: A method for preparing a three-dimensional mesh structure copper-based wear-resistant coating, comprising the following steps: ① The stainless steel substrate surface is sandblasted using low-pressure cold spray equipment and ~100 mesh alumina sand. The sandblasting pressure is 0.60~0.70 MPa, the sandblasting angle is ~90°, and the sandblasting distance is 30~35mm. The sandblasted substrate surface is then blown away with compressed air to remove any residual alumina particles.

[0045] ② Low-pressure cold spraying technology is used to deposit a coating bonding layer of -325 mesh pure copper powder on the substrate surface. The number of spraying layers is 1, and the deposition thickness is 150~200 μm.

[0046] The conditions for low-pressure cold spraying technology are as follows: using a DYMET 423 low-pressure cold spraying equipment combined with a three-dimensional CNC slide rail to spray the surface of the sandblasting substrate material in an arc-shaped straight path, with the distance between adjacent spraying paths being 1 mm; the spraying carrier gas is compressed air with a pressure of 0.75~0.85 MPa, a spraying distance of 9 mm, a spraying angle of approximately 90°, a spraying gas heating temperature of 500℃, and a spraying moving speed of 25~35 mm / s.

[0047] ③ Preparation of core-shell structured silver-coated copper spray powder: (1) Surface pretreatment of pure copper powder: 180 g of -325 mesh atomized copper powder was accurately weighed using an electronic balance. The powder was then cleaned with anhydrous ethanol to remove organic matter from its surface, followed by cleaning with deionized water to remove any remaining anhydrous ethanol. Next, 6 g of NaOH and 2.5 g of Na₂CO₃ were dissolved in 200 mL of water, respectively, and used to clean the copper powder, further removing organic matter from its surface. Subsequently, the copper powder cleaned with the alkaline solution was washed 2-3 times with deionized water, followed by acid washing with 6 mL of concentrated hydrochloric acid for 20 minutes to remove the oxide layer. After washing 2-3 times with deionized water, the powder was filtered to obtain the pretreated copper powder.

[0048] (2) Preparation of core-shell structured silver-coated copper powder: First, the pretreated copper powder is stirred and ultrasonically dispersed in 200 mL of a polyvinylpyrrolidone (PVP) aqueous solution with a concentration of 1.5~1.8 g / L to obtain a copper powder-PVP mixed liquid. Then, 100 mL of a 0.2–0.3 mol / L silver nitrate-EDTA mixture was first added to the copper powder-PVP mixture and stirred rapidly. Next, 900 mL of the silver nitrate-EDTA mixture and 1000 mL of a 0.2–0.3 mol / L glucose solution were simultaneously added to the copper powder-PVP mixture, with the addition rate of both solutions controlled at 17–20 mL / min. Silver plating was then performed on the copper powder surface in a 38°C water bath using ultrasonication and stirring for 3 hours. After silver plating, the upper layer of solution was removed to obtain the powder. Finally, the powder was washed with a NaOH solution with a concentration of 1.0~2.0 mol / L to remove residual EDTA. The powder was then washed with deionized water until the solution was colorless and filtered. The filtered powder was dried at 60℃ to constant weight to obtain core-shell structured silver-coated copper powder.

[0049] (3) Preparation of core-shell structured silver-coated copper spray powder: The core-shell structured silver-coated copper powder was subjected to vacuum heat treatment at 300 ℃, held for 2 h, and heated at a rate of 10 ℃ / min, and then sieved to obtain a core-shell structured silver-coated copper spray powder with a particle size of -300 mesh.

[0050] Low-pressure cold spraying technology is used to deposit core-shell structured silver-coated copper powder onto the surface of a pure copper bonding layer. Three layers are continuously sprayed to obtain a silver-containing three-dimensional mesh structure copper-based wear-resistant coating.

[0051] Among them, the conditions for low-pressure cold spraying technology are the same as those in step ②.

[0052] The obtained three-dimensional mesh-structured copper-based wear-resistant coating has a uniform surface and an average thickness of approximately 750 μm. SEM images of the coating cross-section are shown below.Figure 1 As shown.

[0053] The obtained coating was subjected to tribological property testing on a high-speed reciprocating friction and wear testing machine; the friction test conditions and methods were the same as in Example 1. The tribological property test results of the coating are as follows: Figure 2 As shown, the average coefficient of friction of the coating is 0.76, and the measured wear rate of the coating is (1.94±0.19)×10. -4 mm 3 / N·m.

[0054] Example 3: A method for preparing a three-dimensional mesh structure copper-based wear-resistant coating, comprising the following steps: ① The stainless steel substrate surface is sandblasted using low-pressure cold spray equipment and ~100 mesh alumina sand. The sandblasting pressure is 0.60~0.70 MPa, the sandblasting angle is ~90°, and the sandblasting distance is 30~35mm. The sandblasted substrate surface is then blown away with compressed air to remove any residual alumina particles.

[0055] ② Low-pressure cold spraying technology is used to deposit a coating bonding layer of -325 mesh pure copper powder on the substrate surface. The number of spraying layers is 1, and the deposition thickness is 120~200 μm.

[0056] The conditions for low-pressure cold spraying technology are as follows: using a DYMET 423 low-pressure cold spraying equipment combined with a three-dimensional CNC slide rail to spray the surface of the sandblasting substrate material in an arc-shaped straight path, with the distance between adjacent spraying paths being 1 mm; the spraying carrier gas is compressed air with a pressure of 0.75~0.85 MPa, a spraying distance of 11 mm, a spraying angle of approximately 90°, a spraying gas heating temperature of 500℃, and a spraying moving speed of 25~35 mm / s.

[0057] ③ Preparation of core-shell structured silver-coated copper spray powder: (1) Surface pretreatment of pure copper powder: 180 g of -325 mesh atomized copper powder was accurately weighed using an electronic balance. The powder was then cleaned with anhydrous ethanol to remove organic matter from its surface, followed by cleaning with deionized water to remove any remaining anhydrous ethanol. Next, 6 g of NaOH and 2.5 g of Na₂CO₃ were dissolved in 200 mL of water, and these solutions were used to clean the surface of the copper powder, further removing organic matter. The copper powder cleaned with the alkaline solution was then washed 2-3 times with deionized water, followed by acid washing with 6 mL of concentrated hydrochloric acid for 20 minutes to remove the oxide layer. This was repeated 2-3 times with deionized water, and the powder was then filtered to obtain the pretreated copper powder.

[0058] (2) Preparation of core-shell structured silver-coated copper powder: First, the pretreated copper powder is stirred and ultrasonically dispersed in 200 mL of a polyvinylpyrrolidone (PVP) aqueous solution with a concentration of 1.5~1.8 g / L to obtain a copper powder-PVP mixed liquid. Then, 100 mL of a 0.2–0.3 mol / L silver nitrate-EDTA mixture was added to the copper powder-PVP mixture and stirred rapidly. Next, 900 mL of the silver nitrate-EDTA mixture and 1000 mL of a 0.2–0.3 mol / L glucose solution were simultaneously added to the copper powder-PVP mixture, with the addition rate of both solutions controlled at 15–20 mL / min. Silver plating was then performed on the copper powder surface in a 42°C water bath using ultrasonication and stirring for 3 hours. After silver plating, the upper layer of solution was removed to obtain the powder. Finally, the powder was washed with a NaOH solution with a concentration of 1.0~2.0 mol / L to remove residual EDTA. The powder was then washed with deionized water until the solution was colorless and filtered. The filtered powder was dried at 60℃ to constant weight to obtain core-shell structured silver-coated copper powder.

[0059] (3) Preparation of core-shell structured silver-coated copper spray powder: The core-shell structured silver-coated copper powder was subjected to vacuum heat treatment at 400℃ for 2 hours and a heating rate of 10℃ / min, followed by sieving to obtain a core-shell structured silver-coated copper spraying powder with a particle size of -300 mesh.

[0060] Low-pressure cold spraying technology is used to deposit core-shell structured silver-coated copper powder onto the surface of a pure copper bonding layer. Three layers are continuously sprayed to obtain a silver-containing three-dimensional mesh structure copper-based wear-resistant coating.

[0061] Among them, the conditions for low-pressure cold spraying technology are the same as those in step ②.

[0062] The resulting three-dimensional mesh structure copper-based wear-resistant coating has a uniform surface, good bonding between the coating and the substrate interface, and an average deposition thickness of approximately 650 μm.

[0063] The obtained coating was subjected to tribological property testing on a high-speed reciprocating friction and wear testing machine; the friction test conditions and methods were the same as in Example 1. The tribological property test results of the coating are as follows: Figure 2 As shown, the average coefficient of friction of the coating is 0.64, and the measured wear rate of the coating is (2.10±0.14)×10. -4 mm 3 / N·m.

Claims

1. A three-dimensional network structured copper-based wear resistant coating, characterized by: The coating is composed of a pure copper adhesive layer and a copper-based wear-resistant layer with a three-dimensional network structure of silver.

2. A three-dimensional network structured copper-based wear resistant coating as claimed in claim 1, wherein: The coating is obtained by layer-by-layer solid-state deposition of core-shell structure silver-coated copper spraying powder on the surface of a stainless steel substrate with a pure copper adhesive layer using low-pressure cold spraying technology.

3. A three-dimensional network structured copper-based wear resistant coating as claimed in claim 2, wherein: The particle size of the core-shell structure silver-coated copper spraying powder is -300 mesh.

4. A three-dimensional network structured copper-based wear resistant coating according to claim 2 or 3, characterized in that: The core-shell structure silver-coated copper spraying powder is prepared by the following method: (1) Surface pretreatment of pure copper powder: 180 g of pure copper powder is sequentially cleaned with anhydrous ethanol, deionized water, a 3 g / 100 mL NaOH solution, a 2.5 g / 200 mL Na2CO3 solution, deionized water, concentrated HCl, and deionized water to remove surface impurities, organic matter, and an oxide layer. The pretreated copper powder is obtained by filtration. (2) Preparation of core-shell structure silver-coated copper powder: First, the pretreated copper powder is stirred and ultrasonically dispersed in 200 mL of a 1.5-1.8 g / L polyvinylpyrrolidone aqueous solution to obtain a copper powder-PVP mixture. Then, 100 mL of a 0.2-0.3 mol / L silver nitrate-ethylenediaminetetraacetic acid mixture is added to the copper powder-PVP mixture and stirred rapidly. Simultaneously, 900 mL of a silver nitrate-ethylenediaminetetraacetic acid mixture and 1000 mL of a 0.2-0.3 mol / L glucose solution are added to the copper powder-PVP mixture at an addition rate of 15-20 mL / min. The copper powder surface is plated with silver in an ultrasonic and stirring water bath at 38-42°C for 2-3 h. After plating, the upper solution is removed, and the powder is obtained. Finally, the powder is cleaned with a 1.0-2.0 mol / L NaOH solution and deionized water until the solution is colorless. The filtered powder is dried at 60°C to constant weight to obtain the core-shell structure silver-coated copper powder. (3) Preparation of core-shell structure silver-coated copper spraying powder: The core-shell structure silver-coated copper powder is sieved after vacuum heat treatment to obtain core-shell structure silver-coated copper spraying powder with a particle size of -300 mesh.

5. A three-dimensional network structured copper-based wear resistant coating as claimed in claim 4, wherein: The pure copper powder in step (1) is a spherical or quasi-spherical powder prepared by atomization with a particle size of -325 mesh.

6. A three-dimensional network structured copper-based wear resistant coating as claimed in claim 4, wherein: The vacuum heat treatment conditions in step (2) are a temperature of 300-400°C, a holding time of 2 h, and a heating rate of 10°C / min.

7. A method for preparing a three-dimensional network structure copper-based wear-resistant coating according to any one of claims 1-6, comprising the following steps: ① The surface of a stainless steel substrate is sandblasted with a low-pressure cold spraying device and ~100 mesh alumina sand, and the sandblasted substrate surface is blown with compressed air to remove residual alumina particles; ② A -325 mesh pure copper powder is deposited on the substrate surface to form a coating adhesive layer using low-pressure cold spraying technology, with 1 layer and a deposition thickness of 100-200 μm. ③Adopting low pressure cold spraying technology to deposit the core-shell structure silver-coated copper spraying powder on the surface of the pure copper adhesive layer, continuously and repeatedly spraying 3-6 layers, and the total thickness of the deposition is 600-750 μm, so as to obtain the silver-containing three-dimensional network structure copper-based wear-resistant coating.

8. A method of producing a three-dimensional network structure copper-based wear resistant coating as claimed in claim 7, characterized in that: The sandblasting treatment condition in the step ① refers to a sandblasting pressure of 0.60-0.70 MPa, a sandblasting angle of ~90°, and a sandblasting distance of 30-35 mm.

9. A method of producing a three-dimensional network structure copper-based wear resistant coating as claimed in claim 7, characterized in that: The low pressure cold spraying technology condition in the step ② and the step ③ refers to adopting a spraying system composed of a low pressure cold spraying equipment and a three-dimensional numerical control slide rail, using compressed air as the working gas, the gas pressure being 0.75-0.85 MPa, controlling the spray gun to perform planar and repeated spraying through the three-dimensional numerical control slide rail in an arch-shaped spraying path, the interval between adjacent spraying paths being 1 mm, the spraying moving speed being 25-35 mm / s, the spraying angle being ~90°, the spraying distance being 8-11 mm, and the spraying gas heating temperature being 400-500 ℃.

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