A friction-reducing wear-resistant coating material and a method for producing and using the same

Abstract

The application discloses a kind of antifriction wear-resistant coating materials and its preparation method and application, including the following steps: using laser cladding to be cladded in substrate with metal-based powder, obtain laser cladding layer;The surface of laser cladding layer is laser etched, and laser cladding layer with surface texture is obtained;Fill powder in the texture of laser cladding layer with texture, and fill powder fills up and fills flat with texture, and the filled powder is melted using laser and forms solid layer, so that antifriction wear-resistant coating material is prepared.The application is based on original laser cladding coating, and by texture processing and the way of secondary processing filled powder of selective laser melting technology, self-lubricating coating is prepared in texture pit, which does not affect the original phase, microstructure, density and wear resistance of laser cladding coating, and can further reduce the friction coefficient of coating by self-lubricating coating in texture pit, so that high-performance coating with wear resistance and antifriction function is prepared.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of coating preparation, and in particular to a friction-reducing wear-resistant coating material and a preparation method and application thereof. BACKGROUND

[0002] Surface wear problems of traditional mechanical parts during long-term frictional movement are key factors affecting the operation efficiency and reliability of equipment. In view of such problems, surface coating technology has become an important solution to improve the wear resistance of parts. Compared with traditional surface treatment processes such as spraying, electroplating, PVD (physical vapor deposition) and CVD (chemical vapor deposition), laser cladding technology shows significant advantages: first, the coating thickness can be precisely controlled through process parameters (0.1-5mm range), which can not only realize precise processing of thin coatings, but also meet the strengthening needs of thick coatings; second, the degree of freedom of material selection is extremely high, and high-performance materials such as nickel-based / cobalt-based alloy, tungsten carbide composite material and ceramic reinforced metal can be flexibly selected according to the working condition requirements; more importantly, the high-density coating (porosity <2%) formed by laser cladding through metallurgical bonding has a bonding strength of more than 3 times that of traditional thermal spraying technology, effectively avoiding the problem of coating peeling. In harsh wear-resistant environments such as heavy load, high temperature and corrosion, the technology can extend the service life of parts by 3-8 times, significantly reducing equipment maintenance costs.

[0003] The laser cladding coating is mainly based on metal base, and the existing coating material system has good wear resistance, but its friction coefficient is generally high, usually between 0.5-1, and the friction reduction is poor. In the process of preparing the coating by laser cladding, traditional solid lubricants (such as graphene, MoS2, WS2, etc.) are prone to burnout due to their low melting point under the action of high-temperature laser beams. High-energy laser not only causes the lubricant to fail, but also generates other harmful compounds inside the coating, thereby reducing the performance of the coating.

[0004] Therefore, the actual effect of traditional solid lubricants is often limited due to their low melting point, easy burning, easy agglomeration, poor interface bonding and other problems. It is necessary to develop a better preparation method of friction-reducing wear-resistant coating material. SUMMARY

[0005] The purpose of the present application is to provide a friction-reducing wear-resistant coating material and a preparation method and application thereof. Based on the original laser cladding coating, the self-lubricating coating is prepared in the texture recess by means of texture processing and selective laser melting (SLM) technology to fill the powder, which does not affect the original phase, microstructure, density and wear resistance of the laser cladding coating, and further reduces the friction coefficient of the coating with the help of the self-lubricating coating in the texture recess, thereby preparing a high-performance coating with wear resistance and friction reduction functions.

[0006] In order to achieve the above object, the present application adopts the following technical solutions:

[0007] The first aspect of the present application is to provide a preparation method of a friction-reducing wear-resistant coating material, comprising the following steps:

[0008] (1) using laser cladding to clad metal-based powder on a substrate to obtain a laser cladding layer;

[0009] (2) after cleaning the laser cladding layer, laser etching the surface of the laser cladding layer to obtain a laser cladding layer with a textured surface;

[0010] (3) filling powder in the texture of the laser cladding layer with texture, and filling the powder to fill and flatten the texture, and using laser to melt the filling powder and form a solid layer, thereby preparing a friction-reducing wear-resistant coating material.

[0011] As a preferred embodiment,

[0012] Step (1),

[0013] The metal-based powder is selected from Ni-Sn alloy; preferably, the mass ratio of Ni to Sn is 6:4 to 7:3; and / or,

[0014] The substrate is a steel substrate; preferably 45# steel, stainless steel, etc.

[0015] As a preferred embodiment,

[0016] Step (1),

[0017] The laser of the laser cladding is infrared laser with a wavelength of 1060-1080 nm; and / or,

[0018] The power of the laser cladding is 2000W-2500W; and / or,

[0019] The powder feeding amount of the laser cladding is 5-10g / min; and / or,

[0020] The protective gas of the laser cladding is inert gas; and / or,

[0021] The flow rate of the protective gas of the laser cladding is 6L / min-12L / min; and / or,

[0022] The included angle between the laser head of the laser cladding and the horizontal plane of the substrate is 10°-30°; and / or,

[0023] The defocusing amount of the laser head of the laser cladding to the surface of the substrate is always kept at 20-24mm; and / or,

[0024] The lap rate of the laser cladding is 80%-90%; and / or,

[0025] The scanning speed of the laser cladding is 150mm / s-200mm / s.

[0026] As a preferred embodiment,

[0027] Step (2),

[0028] The laser processing speed of the laser etching is 1000-1200mm / s; and / or,

[0029] The laser current of the laser etching is 5-10A; and / or,

[0030] The frequency of the laser etching is 80-200kHz; and / or,

[0031] The Q pulse width of the laser etching is 1-10μs; and / or,

[0032] The light-on delay of the laser etching is -200-100μs; and / or,

[0033] The light-off delay of the laser etching is 100-200μs; and / or,

[0034] The end delay of the laser etching is 100-200μs; and / or,

[0035] The corner delay of the laser etching is 50-150μs; and / or,

[0036] The filling radius of the laser etching is 20-50μm.

[0037] As a preferred embodiment,

[0038] Step (2),

[0039] In the laser cladding layer with the texture,

[0040] The shape of the texture is a hollow cylinder or a hollow triangular prism or a hollow quadrangular prism; wherein,

[0041] The minimum spacing between the edges of the texture is 50-350μm; and / or,

[0042] The diameter of the hollow cylindrical texture is 100-300μm; and / or,

[0043] The side length of the triangular base of the hollow triangular prism texture is 100-300μm; and / or,

[0044] The side length of the base of the hollow quadrangular prism texture is 100-300μm; and / or,

[0045] The depth of the texture is 50-80 μm.

[0046] As a preferred embodiment,

[0047] Step (3),

[0048] The filling powder is selected from a mixed powder of Co, Cr, Ni and Cu; the molar ratio of Co, Cr, Ni and Cu is 1:1:1:0.5-2.

[0049] As a preferred embodiment,

[0050] In step (3), the filling powder is at least melted by laser,

[0051] The laser power is 200-300 W; and / or,

[0052] The laser scanning speed is 800-1200 mm / s; and / or,

[0053] The protective gas of the laser is inert gas; and / or,

[0054] The protective gas flow of the laser is 3 L / min-5 L / min.

[0055] The preparation process of the friction-reducing wear-resistant coating of the present application is as follows:

[0056] The metal-based powder (Ni-Sn system, particle size 15-53 μm, purity 99% spherical powder) is dried in a drying oven and cooled to room temperature, and the drying temperature is 80-100 °C. The coating is prepared on a 316L substrate by laser cladding, and the coaxial powder feeding method is used to prepare the coating; the protective gas is inert gas argon (purity 99.999%), and the surface of the 316L (or other substrate material) is polished using sandpaper to remove the surface oxide layer. The coating is prepared using a fiber laser cladding device, the laser head is aligned with the 316L surface to be cladded by the robot controller, the laser head is slightly tilted to form a certain angle (10°-30°) with the surface to be cladded; the distance between the laser head and the substrate surface is adjusted by the robot controller, so that the defocusing amount between the laser head and the substrate surface is always kept at 20-24 mm, the coating overlap rate is set, the optimal forming quality of the present application selects the overlap rate of 80%-90%, the high-speed reciprocating platform is opened to set the platform moving speed, the selected speed is 150 mm / s-200 mm / s, the external control is selected, and the powder feeding switch is controlled by the program in the robot controller; the laser power in the laser system is set to 2000 W-2500 W, and the light output waiting time is set to 2 s, after the above steps are completed, the program is started to prepare the coating. The powder feeder, protective gas and laser system are observed during the cladding process.

[0057] After the coating is prepared, a solid nanosecond ultraviolet laser is used to prepare the texture on the surface of the coating, and a regular texture is prepared on the surface of the coating. The specific processing experiment steps are as follows: first, the surface of the prepared metal-based coating is polished to remove surface oxides, and is placed in alcohol for ultrasonic cleaning for 20-40 min to facilitate laser texture processing. The treated metal-based coating is placed on the workbench and positioned, the laser processing speed is 1000-1200 mm / s, the current is 5-10 A, the frequency is 80-200 kHz, the Q pulse width is 1-10 μs, the light-on delay is -200-100 μs, the light-off delay is 100-200 μs, the end delay is 100-200 μs, the corner delay is 50-150 μs, the filling radius is 20-50 μm, the minimum distance between the edges of the texture is 50-350 μm, the diameter is 100-300 μm, and the processing number is 3-8 times, so that the texture depth is 50-80 μm.

[0058] After the texture is prepared, the pits prepared by the texture are filled with filling powder using selective laser melting (SLM) technology (spot diameter of 80-100 μm) on the surface. Since SLM melts metal powder layer by layer with high precision laser, and at the same time, its high-energy laser beam can promote the refinement of metal grains at 10 6 -10 8 W / cm² energy density and 10 3 -10 6 K / s rapid cooling rate, so it can significantly improve the performance of the material. The specific processing experiment steps are as follows: first, clean the surface of the substrate to ensure that there is no oil, oxide or other impurities. Then, fill the copper powder, and then perform laser scanning. According to the preset 3D model slice data, control the laser beam to scan the powder layer according to the specific path, melt the powder and form a solid layer. The laser power is 200-300 W, the scanning speed is 800-1200 mm / s, the layer thickness is 30-50 μm, and the scanning pitch is 80-120 μm. The protective gas is argon (purity 99.999%), and the protective gas flow is 3 L / min-5 L / min. During the printing process, attention should be paid to ensure that the powder is dry, has good fluidity, and has uniform particle size distribution. Table 1 shows the performance parameters of the coating after filling with different filling powders.

[0059] In addition, by preparing the high-entropy alloy coating in the texture pit through the SLM technology, the Cu element in the filling powder reacts with the Sn element in the laser cladding coating at high temperature to generate Cu3Sn lubricating phase in situ, and the friction reducing performance of the coating is further improved. In addition, for the existing materials such as Ni-based alloy, the high-entropy alloy coating can realize good metallurgical bonding due to the excellent comprehensive performance, high strength and high density, and the overall performance of the coating is stable. Through this design, the wear resistance of the coating is ensured, and the friction reducing property is realized by using the self-lubricating property of Cu, so that the high-performance coating with high wear resistance and low friction coefficient is finally prepared, and the comprehensive performance of the coating is improved.

[0060] Therefore, the present application combines the surface texture technology and the selective laser melting (SLM) technology, and proposes an innovative method: micro-texture pits are processed on the surface of the laser cladding coating, and a self-lubricating coating is prepared in the pits. This method can not only maintain the original phase, microstructure and wear resistance of the laser cladding coating, but also realize the friction reducing effect by means of the self-lubricating coating in the texture pit.

[0061] The second aspect of the present application is to provide a friction-reducing wear-resistant coating material prepared by the method of the first aspect of the present application.

[0062] As a preferred embodiment,

[0063] The hardness of the friction-reducing wear-resistant coating material is 190-260HV;

[0064] The wear scar width of the friction-reducing wear-resistant coating material is 560-620μm;

[0065] The friction coefficient of the friction-reducing wear-resistant coating material is 0.54-0.61.

[0066] The third aspect of the present application is to provide the application of the friction-reducing wear-resistant coating material prepared by the second aspect of the present application in the fields of automobiles, aerospace, marine vessels and energy power. For example, the key components such as bearings, shaft sleeves, gears, hulls, propellers, hydraulic cylinders, piston rods and sleeves which are prone to friction failure.

[0067] Advantages:

[0068] The present application combines the surface texture technology and the selective laser melting (SLM) technology, and proposes an innovative method: micro-texture pits are processed on the surface of the laser cladding coating, and a self-lubricating coating is prepared in the pits. This method can not only maintain the original phase, microstructure and wear resistance of the laser cladding coating, but also realize the friction reducing effect by means of the self-lubricating coating in the texture pit, which can effectively reduce the friction coefficient of the coating and enhance the surface hardness of the coating. BRIEF DESCRIPTION OF DRAWINGS

[0069] Figure 1 Structure diagram of the coated hollow cylindrical texture provided by the embodiment of the present application;

[0070] Figure 2 Structure diagram of the coated hollow cylindrical texture provided by the embodiment of the present application;

[0071] Figure 3 Structure diagram of the coated hollow cylindrical texture provided by the embodiment of the present application;

[0072] Figure 4 Structure diagram of the coated hollow cylindrical texture provided by the embodiment of the present application.

[0073] Explanation of reference signs:

[0074] 1 - filler powder, 2 - laser cladding layer, 3 - substrate. DETAILED DESCRIPTION

[0075] The present application is further described in detail below with the aid of the accompanying drawings and specific embodiments.

[0076] Example 1

[0077] Metal-based powder (Ni-Sn alloy system, mass ratio of Ni and Sn is 6:4, particle size is 15-53 μm, purity is 99% spherical powder) was dried in a drying oven and cooled to room temperature, and the drying temperature was 80°C. The coating was prepared on a 316L stainless steel substrate by laser cladding method, and the coating was prepared by coaxial powder feeding method; the protective gas was inert gas argon (purity 99.999%), the powder feeding amount was selected as 8 g / min, the protective gas flow was 8 L / min, and the surface of the 316L was polished using sandpaper to remove the surface oxide layer. The coating was prepared using a fiber laser cladding device, after the laser head was aligned to the surface to be cladded by the robot controller, the laser head was slightly tilted to present a certain angle (15°) with the surface to be cladded; the distance between the laser head and the substrate surface was adjusted by the robot controller, so that the defocusing amount of the laser head and the substrate surface was always kept at 20 mm, the coating overlap rate was set, the optimal forming quality of the present application selected the overlap rate of 80%, the platform moving speed was set by opening the high-speed reciprocating platform, the selected scanning speed was 150 mm / s, the external control was selected, and the powder feeding switch was controlled by the program in the robot controller; the laser power in the laser system was set to 2000 W, infrared laser, wavelength was 1060 nm; the light output waiting time was set to 2 s, after the above steps were completed, the program was started to prepare the coating. The powder feeder, protective gas and laser system were observed during the cladding process.

[0078] After the coating is prepared (the thickness of the coating is 200 μm), the surface of the coating is textured by using a solid nanosecond ultraviolet laser. Regular textures are prepared on the surface of the coating. The specific processing experimental steps are as follows: first, the surface of the prepared metal-based coating is polished to remove surface oxides, and is ultrasonically cleaned in alcohol for 20 min to facilitate the laser texturing. The treated metal-based coating is placed on a workbench and positioned. The laser processing speed is 1000 mm / s, the current is 10 A, the frequency is 80 kHz, the Q pulse width is 1 μs, the light-on delay is -200 μs, the light-off delay is 100 μs, the end delay is 100 μs, the corner delay is 50 μs, the filling radius is 50 μm, the minimum distance between the edges of the hollow cylindrical texture is 100 μm, the diameter is 100 μm, and the processing number is 5, so that the texture depth is 50 μm. The texture structure is shown in Figure 1 .

[0079] After the texturing is completed, the surface of the coating is filled with high-entropy alloy CoCrNiCu 0.5 powder (the specific composition is shown in Table 2, which refers to a Co, Cr, Ni and Cu mixed powder) by using selective laser melting (SLM) technology. The prepared pits are filled. The specific processing experimental steps are as follows: first, clean the surface of the substrate to ensure that there is no oil, oxide or other impurities. Then, the copper alloy powder filling (the composition of the copper alloy powder is shown in Table 2) is performed, and then laser scanning is performed. According to the preset 3D model slice data, the laser beam is controlled to scan the powder layer according to a specific path, melt the powder and form a solid layer. The laser power is 200 W, the scanning speed is 1000 mm / s, the total layer thickness is 50 μm, and the scanning pitch is 80 μm. The protective gas is argon (purity 99.999%), and the protective gas flow is 5 L / min. During the printing process, attention should be paid to ensure that the powder is dry, has good flowability, and has uniform particle size distribution.

[0080] As shown in Figure 2 , it is a friction-reducing wear-resistant coating material. First, a metal-based powder is cladded on a substrate 3 by laser cladding to obtain a laser cladding layer 2.

[0081] (2) After the laser cladding layer 2 is cleaned, the surface of the laser cladding layer is laser etched to obtain a laser cladding layer with textures on the surface.

[0082] (3) The powder 1 is filled in the textures of the laser cladding layer with textures, and the filled powder fills and flattens the textures. The filled powder is at least melted by laser to form a solid layer, thereby preparing a friction-reducing wear-resistant coating material.

[0083] Example 2

[0084] The preparation method is basically the same as that of Example 1, the only difference is that the composition of the filling powder is different, and the specific composition is shown in Table 2.

[0085] Example 3

[0086] The preparation method is basically the same as that of Example 1, the only difference is that the composition of the filling powder is different, and the specific composition is shown in Table 2.

[0087] Example 4

[0088] The preparation method is basically the same as that of Example 1, the only difference is that the composition of the filling powder is different, and the specific composition is shown in Table 2.

[0089] Example 5

[0090] The preparation method is basically the same as that of Example 1, the only difference is that the shape of the texture is a hollow regular triangular prism texture; the minimum distance between the edges of the texture is 100 μm, the edge length of the triangular base surface of the hollow regular triangular prism texture is 100 μm, and the texture depth is 50 μm, and the texture structure is shown in Figure 3 .

[0091] Example 6

[0092] The preparation method is basically the same as that of Example 1, the only difference is that the shape of the texture is a hollow regular quadrangular prism texture; the minimum distance between the edges of the texture is 100 μm, the edge length of the square base surface of the hollow regular quadrangular prism texture is 100 μm, and the texture depth is 50 μm, and the texture structure is shown in Figure 4 .

[0093] Comparative Example 1

[0094] The preparation method is basically the same as that of Example 1, the only difference is that the Ni-Sn alloy is replaced by only Ni powder.

[0095] Comparative Example 2

[0096] The preparation method is basically the same as that of Example 1, the only difference is that step (3) is not performed, and the filling powder fills the texture of the laser cladding layer with texture, and the filling powder fills the texture completely and fills the texture. The step of using a laser to at least melt the filling powder and form a solid layer.

[0097] Comparative Example 3

[0098] The preparation method is basically the same as that of Example 1, the only difference is that the filling powder is replaced by CoCrNi alloy, and the specific composition is shown in Table 2.

[0099] Table 1 Coating performance parameters after filling with different filling powders

[0100]

[0101] Table 2 Specific ratio of mixed powder formed by Co, Cr, Ni, Cu

[0102]

[0103] It can be seen from the results of Table 1 that Example 1 and Comparative Example 1 show that the Sn element added in the laser cladding coating reacts with the Cu element in the high-entropy alloy at high temperature to generate Cu3Sn lubricating phase in situ, further improving the friction-reducing performance of the coating.

[0104] Example 1 and Comparative Example 2 show that the filling powder improves the hardness of the coating and enhances the wear resistance of the coating.

[0105] Example 1 and Comparative Example 3 show that the filling powder without Cu element cannot generate Cu3Sn lubricating phase in situ with the Sn element in the substrate, which will result in the decline of the friction-reducing performance of the coating.

[0106] The above examples are only examples for clearly illustrating but not limiting the embodiments. For those skilled in the art, other different forms of changes or variations can be made on the basis of the above description. Here, it is not necessary and also impossible to enumerate all the embodiments. The obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. A method for preparing a friction-reducing and wear-resistant coating material, characterized in that, Includes the following steps: (1) A laser cladding layer is obtained by cladding metal-based powder onto a substrate; the metal-based powder is selected from Ni-Sn alloy; (2) After cleaning the laser cladding layer, laser etching is performed on the surface of the laser cladding layer to obtain a laser cladding layer with a textured surface; (3) Powder is filled into the texture of the laser cladding layer with texture, and the filling powder completely fills and flattens the texture. The filling powder is melted by laser to form a solid layer, thereby obtaining a friction-reducing and wear-resistant coating material. The filler powder is selected from a mixture of Co, Cr, Ni and Cu powders; the molar ratio of Co, Cr, Ni and Cu is 1:1:1:0.5-2.

2. The method for preparing the friction-reducing and wear-resistant coating material according to claim 1, characterized in that: Step (1), The substrate is a steel substrate.

3. The method for preparing the friction-reducing and wear-resistant coating material according to claim 1, characterized in that: Step (1), The laser used for laser cladding is an infrared laser with a wavelength of 1060-1080 nm; and / or, The power of the laser cladding is 2000W-2500W; and / or, The powder feeding rate for laser cladding is 5-10 g / min; and / or, The protective gas for laser cladding is an inert gas; and / or, The protective gas flow rate for laser cladding is 6 L / min - 12 L / min; and / or, The angle between the laser head of the laser cladding and the horizontal plane of the substrate is 10°-30°; and / or, The defocusing distance between the laser head and the substrate surface during laser cladding is consistently maintained at 20-24 mm; and / or, The overlap rate of the laser cladding is 80%-90%; and / or, The scanning speed of the laser cladding is 150mm / s-200mm / s.

4. The method for preparing the friction-reducing and wear-resistant coating material according to claim 1, characterized in that: Step (2), The laser etching process has a laser processing speed of 1000-1200 mm / s; and / or, The laser current for the laser etching is 5-10A; and / or, The laser etching frequency is 80-200kHz; and / or, The Q-pulse width of the laser etching is 1-10 μs; and / or, The laser etching switching delay is -200 to 100 μs; and / or, The laser etching has a light-off delay of 100-200 μs; and / or, The laser etching termination delay is 100-200 μs; and / or, The corner delay of the laser etching is 50-150 μs; and / or, The filling radius of the laser etching is 20-50 μm.

5. The method for preparing the friction-reducing and wear-resistant coating material according to claim 1, characterized in that: Step (2), In the textured laser cladding layer, The texture is shaped like a hollow cylinder, a hollow triangular prism, or a hollow quadrangular prism; among which, The minimum spacing between the edges of the texture is 50-350 μm; and / or, The diameter of the hollow cylindrical texture is 100-300 μm; and / or, The side length of the triangular base of the hollow regular triangular prism texture is 100-300 μm; and / or, The side length of the base of the hollow square prism texture is 100-300 μm; and / or, The depth of the texture is 50-80 μm.

6. The method for preparing the friction-reducing and wear-resistant coating material according to claim 1, characterized in that: Step (3), when the filler powder is melted by laser, The laser power is 200-300W; and / or, The laser scanning speed is 800-1200 mm / s; and / or, The protective gas for the laser is an inert gas; and / or, The protective gas flow rate for the laser is 3L / min-5L / min.

7. The friction-reducing and wear-resistant coating material prepared by the method according to any one of claims 1-6.

8. The friction-reducing and wear-resistant coating material according to claim 7, characterized in that, The hardness of the friction-reducing and wear-resistant coating material is 390-460 HV; The wear-scratch width of the friction-reducing and wear-resistant coating material is 560-620 μm; The friction coefficient of the friction-reducing and wear-resistant coating material is 0.40-0.

55.

9. The application of the friction-reducing and wear-resistant coating material prepared according to claim 8 in automobiles, aerospace, marine vessels, and energy power.

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