Method and coating for preparing high-entropy alloy wear-resistant coatings using ultra-high-speed laser cladding

Abstract

This invention discloses a method for preparing high-entropy alloy wear-resistant coatings by ultra-high-speed laser cladding, comprising the following steps: S1, using metal powders Fe, Co, Cr, Ni, W and Ta as raw materials, ball milling and mixing to prepare FeCoCrNiW x Ta y S2. Pre-treat the substrate surface to remove surface oxide scale and impurities; S3. Use ultra-high-speed laser cladding technology to clad Ni625 alloy powder onto the substrate surface to prepare a transition layer, and then polish and clean the surface of the transition layer; S4. Use ultra-high-speed laser cladding technology to clad FeCoCrNiW x Ta y A working layer is prepared by cladding high-entropy alloy powder onto the surface of a transition layer to obtain the finished product. This invention first prepares a transition layer on the workpiece, and then prepares the high-entropy alloy working layer, which effectively alleviates the performance difference between the working layer and the sample substrate, improves the problem of easy cracking of the high-entropy alloy working layer, and greatly enhances the overall protective effect of the coating.

Description

Technical Field

[0001] This invention relates to the field of metal material coating technology, specifically to a method and coating for preparing high-entropy alloy wear-resistant coatings using ultra-high-speed laser cladding. Background Technology

[0002] Mechanical components are subject to surface friction and wear under various operating conditions during service. Hydraulic piston rods, being key connecting components supporting piston work, undergo frequent reciprocating motion during operation. Marine cylinder piston rods, in particular, are prone to surface wear and damage under the influence of hard particles such as sand and gravel, as well as long-term seawater impact loads, which can lead to failure in severe cases. The quality of their surface directly affects the lifespan and reliability of the entire cylinder product. Therefore, to improve the service life of cylinder piston rods, a uniform, high-strength, high-hardness, and wear-resistant surface-hardened coating is often prepared on their surface. The coating material and preparation process play a decisive role in the quality of the coating.

[0003] Existing protective coatings for parts are generally prepared by plasma spraying or zinc plating, but these are prone to peeling and the required hardness is difficult to achieve. A small number of parts are treated with laser cladding of iron-based alloy powder, but the resulting coating has a hardness of only 500-600 HV, poor wear resistance, and is also prone to cracking.

[0004] Ultra-high-speed laser cladding technology, belonging to the fields of advanced and green manufacturing, is a novel surface treatment technology. It utilizes a high-energy-density laser beam to fully melt powder before it contacts the substrate, causing it to fall into the substrate's molten pool as droplets. After extremely rapid solidification, the powder achieves a metallurgical bond with the substrate surface, significantly improving the substrate's wear resistance, corrosion resistance, and oxidation resistance. The cladding layer prepared by ultra-high-speed laser cladding has advantages such as metallurgical bonding with the substrate, low dilution rate, fine and dense microstructure, and high performance. Using ultra-high-speed laser cladding for surface strengthening and localized repair of piston rods is of great significance for improving their service life, reducing remanufacturing costs, and conserving metal resources.

[0005] High-entropy alloys are a class of novel materials with excellent properties, attracting widespread attention from the scientific community due to their superior mechanical properties, corrosion resistance, and excellent thermal stability. High-entropy alloys are composed of five or more elements, each with an atomic fraction between 5% and 35%. Their high configurational entropy enhances the phase stability of the solid solution, thus promoting the formation of simple FCC or BCC solid solutions. Due to the designability of the composition of high-entropy alloys, their properties exhibit a "cocktail effect," leading to a wide range of applications. High-entropy alloy systems display excellent mechanical behavior, such as high strength, high hardness, and resistance to high-temperature oxidation, making them highly promising for applications in the machinery manufacturing field.

[0006] Therefore, it is necessary to develop a method for preparing high-entropy alloy wear-resistant coatings using ultra-high-speed laser cladding to obtain high-hardness, wear-resistant, and low-crack-sensitivity high-entropy alloy wear-resistant coatings, thereby improving the life and reliability of hydraulic cylinder piston rods. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the aforementioned background technology and provide a method for preparing high-entropy alloy wear-resistant coatings using ultra-high-speed laser cladding, thereby obtaining high-entropy alloy wear-resistant coatings with high hardness, wear resistance, and low crack sensitivity, and improving the life and reliability of hydraulic cylinder piston rods.

[0008] The technical solution of this invention is: a method for preparing a high-entropy alloy wear-resistant coating by ultra-high-speed laser cladding, comprising the following steps:

[0009] S1, based on the target alloy FeCoCrNiW x Ta y The design composition involves weighing metal powders of Fe, Co, Cr, Ni, W, and Ta, where x and y are molar ratios, 0.4 ≤ x ≤ 0.6 and 0.4 ≤ y ≤ 0.6. The mixture is then ball-milled to prepare FeCoCrNiW. x Ta y High-entropy alloy powder;

[0010] S2. Pre-treat the substrate surface to remove surface oxide scale and impurities;

[0011] S3. Using ultra-high-speed laser cladding technology, Ni625 alloy powder is clad onto the surface of the substrate to prepare a transition layer, and the surface of the transition layer is polished and cleaned.

[0012] S4. Using an ultra-high-speed laser cladding process, the FeCoCrNiW obtained in step S1 is clad... x Ta y A working layer is prepared by cladding high-entropy alloy powder on the surface of the transition layer to obtain the finished product.

[0013] Preferably, in step S1, the particle sizes of the metal powders Fe, Co, Cr, Ni, W, and Ta are all 20–53 μm, and the mixture is ball-milled for 10–24 h to obtain FeCoCrNiW. x Ta y High-entropy alloy powder. The purity of the metal powders Fe, Co, Cr, Ni, W and Ta is greater than 99.9%. Powder purity generally refers to mass percentage content.

[0014] Preferably, in step S1, the metal powders Fe, Co, Cr, Ni, W, and Ta are used as raw materials in a molar ratio of 1:1:1:1:(0.4-0.6):(0.4-0.6). More preferably, the metal powders Fe, Co, Cr, Ni, W, and Ta are used as raw materials in a molar ratio of 1:1:1:1:0.4:0.4, 1:1:1:1:0.5:0.5, or 1:1:1:1:0.6:0.6, corresponding to x = 0.4, y = 0.4, x = 0.5, y = 0.5, or x = 0.6, y = 0.6.

[0015] Preferably, in step S2, the pretreatment includes: removing surface oxides with a grinding wheel, then sanding the substrate with sandpaper, and cleaning the surface with anhydrous ethanol. More preferably, the substrate is sanded stepwise with 200-600# sandpaper.

[0016] Preferably, in step S3, the ultra-high-speed laser cladding process parameters include:

[0017] The laser spot diameter is 2-3 mm, the laser power is 3300-4000 kW, the linear speed is 10-20 m / min, the powder feed rate is 40-50 g / min, the single-pass transverse feed rate is 1-1.3 mm, the protective gas flow rate is 7-10 L / min, and the powder feeding gas flow rate is 15-20 L / min.

[0018] Preferably, in step S3, the Ni625 alloy powder has a particle size of 20–53 μm and the transition layer has a thickness of 0.5 mm–0.8 mm.

[0019] Preferably, in step S3, the polishing and cleaning includes: removing the loose powder from the surface of the Ni625 transition layer with a grinding wheel, polishing it smooth, then polishing the Ni625 transition layer with sandpaper, cleaning the surface with anhydrous ethanol, and drying it under natural conditions. More preferably, the Ni625 transition layer is polished step by step with 200-600# sandpaper.

[0020] Preferably, in step S4, the ultra-high-speed laser cladding process parameters include:

[0021] The laser spot diameter is 2-3 mm, the laser power is 4000-4500 kW, the linear velocity is 6-15 m / min, the powder feed rate is 30-40 g / min, the feed rate is 1.2-1.6 mm / r, the protective gas flow rate is 7-10 L / min, and the powder feeding gas flow rate is 15-20 L / min.

[0022] Preferably, in step S4, the thickness of the working layer is 0.6 mm to 1 mm.

[0023] This invention also provides a high-entropy alloy wear-resistant coating, prepared by any of the above-mentioned methods for preparing high-entropy alloy wear-resistant coatings by ultra-high-speed laser cladding. The high-entropy alloy wear-resistant coating includes a transition layer on the surface of the substrate and a working layer on the surface of the transition layer.

[0024] The transition layer is formed by Ni625 alloy powder on the surface of the substrate using an ultra-high-speed laser cladding process.

[0025] The working layer is made of FeCoCrNiW x Ta y High-entropy alloy powder was prepared on the surface of the transition layer using an ultra-high-speed laser cladding process. The chemical formula is FeCoCrNiW. x Ta y In the equation, x and y are molar ratios, where 0.4 ≤ x ≤ 0.6 and 0.4 ≤ y ≤ 0.6.

[0026] Preferably, the thickness of the transition layer is 0.5 mm to 0.8 mm, and the thickness of the working layer is 0.6 mm to 1 mm.

[0027] The beneficial effects of this invention are as follows:

[0028] 1. First, a Ni625 transition layer is prepared on the workpiece, and then FeCoCrNiW is prepared on the surface of the Ni625 transition layer. x Ta y The high-entropy alloy working layer is achieved because the Ni625 transition layer effectively mitigates the performance difference between the working layer and the sample substrate, improving the high hardness of FeCoCrNiW. x Ta y The problem of cracking in the high-entropy alloy working layer has been solved, which greatly improves the overall protective effect of the coating.

[0029] 2. The FeCoCrNiW prepared by this invention x Ta y The high-entropy alloy working layer uses an alloy with atomic ratios of Fe, Co, Cr, and Ni as the matrix. The performance and quality of the working layer are controlled by adding certain amounts of W and Ta elements. The addition of Ta elements improves the cracking tendency of the working layer, while the addition of W elements further strengthens the FeCoCrNiW alloy. x Ta y The hardness of the high-entropy alloy working layer allows the room temperature hardness of the working layer to reach 961HV.

[0030] 3. This invention utilizes a high-energy-density laser beam to prepare a high-hardness, high-wear-resistant, and high-entropy alloy coating on the surface of a workpiece, which can significantly improve the service life of the workpiece and reduce remanufacturing costs. Attached Figure Description

[0031] Figure 1 FeCoCrNiW prepared in Example 1 of this invention0.5 Ta. 0.5 Morphology of high-entropy alloy powder.

[0032] Figure 2 This is a SEM microstructure image of the high-entropy alloy wear-resistant coating prepared in Example 1 of the present invention.

[0033] Figure 3 The image shows the microhardness curve of the high-entropy alloy wear-resistant coating prepared in Example 1 of this invention. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the following embodiments provide a more detailed description of the invention. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Unless otherwise specified, all pharmaceuticals used in the embodiments are commercially available products, and all methods used are conventional methods in the art. In the following embodiments, the Ni625 alloy powder is a commercially available product from China Machinery New Materials Research Institute (Zhengzhou) Co., Ltd., with a particle size of 20–53 μm. The substrate is commercially available No. 45 steel bar.

[0035] Example 1

[0036] This embodiment provides a method for preparing high-entropy alloy wear-resistant coatings by ultra-high-speed laser cladding, the steps of which are as follows:

[0037] S1. Preparation of high-entropy alloy powders. Fe, Co, Cr, Ni, W, and Ta metal powders with particle sizes of 20–53 μm were selected, specifically FeCoCrNiW. x Ta y The high-entropy alloy powder raw material, consisting of metals Fe, Co, Cr, Ni, W, and Ta, all with a purity greater than 99.9%, was weighed according to a molar ratio of Fe, Co, Cr, Ni, W, and Ta of 1:1:1:1:0.5:0.5 (in this example, x = 0.5, y = 0.5). The powder was then ground and mixed using a ball mill for 10 hours, employing zirconia grinding beads with diameters of 10 mm, 5 mm, and 2 mm, at a mill speed of 200 r / min to obtain FeCoCrNiW. 0.5 Ta 0.5 High-entropy alloy powder;

[0038] S2. 45# steel bar was selected as the experimental substrate, with a diameter of 50mm and a length of 500mm. Pretreatment was carried out: the surface oxide was removed with a grinding wheel, the substrate material was polished step by step with 200-600# sandpaper, the surface was cleaned with anhydrous ethanol, and then air-dried in an airy state.

[0039] S3. Under argon protection, a transition layer is prepared by cladding Ni625 alloy powder onto the surface of a substrate using an ultra-high-speed laser cladding process. The Ni625 alloy powder has been pre-dried in a vacuum drying oven at 100°C for 4 hours and loaded into a powder feeder. The key process parameters for ultra-high-speed laser cladding are as follows: laser spot diameter 2.2 mm, laser power: 3500 kW, linear velocity: 10 m / min, powder feed rate 42 g / min, feed rate: 1.1 mm / r, protective gas flow rate: 7.5 L / min, powder feeding gas flow rate: 17 L / min.

[0040] The transition layer surface is polished and cleaned, specifically: use a grinding wheel to remove the floating powder on the transition layer surface, polish it smooth, use 200-600# sandpaper to polish the transition layer step by step, clean the surface with anhydrous ethanol, and let it air dry naturally.

[0041] S4. Under argon protection, using an ultra-high-speed laser cladding process, the FeCoCrNiW obtained in step S1 is clad... 0.5 Ta 0.5 FeCoCrNiW prepared by cladding high-entropy alloy powder on the surface of the transition layer 0.5 Ta 0.5 High-entropy alloy working layer, FeCoCrNiW 0.5 Ta 0.5 The high-entropy alloy powder has been pre-dried in a vacuum drying oven at 100℃ for 4 hours and loaded into the powder feeder. The key process parameters of ultra-high speed laser cladding are as follows: laser spot diameter 2.2mm, laser power: 4300kW, linear speed: 8m / min, powder feeding rate 35g / min, feed rate: 1.3mm / r, protective gas flow rate: 7.5L / min, powder feeding gas flow rate: 17L / min;

[0042] After the cladding is completed, the test bar is cooled to room temperature to obtain the product.

[0043] Measurements showed that the Ni625 transition layer thickness of the product prepared in this embodiment was 0.5–0.6 mm, and the FeCoCrNiW content was [not specified]. 0.5 Ta 0.5 The thickness of the high-entropy alloy working layer is 0.6–0.7 mm.

[0044] Example 2

[0045] This embodiment provides a method for preparing high-entropy alloy wear-resistant coatings by ultra-high-speed laser cladding, the steps of which are as follows:

[0046] S1. Preparation of high-entropy alloy powders. Fe, Co, Cr, Ni, W, and Ta metal powders with particle sizes of 20–53 μm were selected, specifically FeCoCrNiW. x Ta yThe high-entropy alloy powder raw material, consisting of Fe, Co, Cr, Ni, W, and Ta, all with a purity greater than 99.9%, was weighed according to a molar ratio of Fe, Co, Cr, Ni, W, and Ta of 1:1:1:1:0.4:0.4 (in this example, x = 0.4, y = 0.4). The powder was then ground and mixed using a ball mill for 10 hours, employing zirconia grinding beads with diameters of 10 mm, 5 mm, and 2 mm, at a mill speed of 200 r / min to obtain FeCoCrNiW. 0.4 Ta 0.4 High-entropy alloy powder;

[0047] S2. 45# steel bar was selected as the experimental substrate, with a diameter of 50mm and a length of 500mm. Pretreatment was carried out: the surface oxide was removed with a grinding wheel, the substrate material was polished step by step with 200-600# sandpaper, the surface was cleaned with anhydrous ethanol, and then air-dried in an airy state.

[0048] S3. Under argon protection, a transition layer is prepared by cladding Ni625 alloy powder onto the surface of a substrate using an ultra-high-speed laser cladding process. The Ni625 alloy powder has been pre-dried in a vacuum drying oven at 100°C for 4 hours and loaded into a powder feeder. The key process parameters for ultra-high-speed laser cladding are as follows: laser spot diameter 2.2 mm, laser power: 3500 kW, linear velocity: 10 m / min, powder feed rate 42 g / min, feed rate: 1.1 mm / r, protective gas flow rate: 7.5 L / min, powder feeding gas flow rate: 17 L / min.

[0049] The transition layer surface is polished and cleaned, specifically: use a grinding wheel to remove the floating powder on the transition layer surface, polish it smooth, use 200-600# sandpaper to polish the transition layer, clean the surface with anhydrous ethanol, and let it air dry naturally.

[0050] S4. Under argon protection, the FeCoCrNiW obtained in step S1 is processed... 0.4 Ta 0.4 High-entropy alloy powder is used to prepare FeCoCrNiW on the surface of the transition layer. 0.4 Ta 0.4 High-entropy alloy working layer, FeCoCrNiW 0.4 Ta 0.4 The high-entropy alloy powder has been pre-dried in a vacuum drying oven at 100℃ for 4 hours and loaded into the powder feeder. The key process parameters of ultra-high speed laser cladding are as follows: laser spot diameter 2.2mm, laser power: 4000kW, linear speed: 7m / min, powder feeding rate 32g / min, feed rate: 1.4mm / r, protective gas flow rate: 7.5L / min, powder feeding gas flow rate: 17L / min;

[0051] After the cladding is completed, the test bar is cooled to room temperature to obtain the product.

[0052] Measurements showed that the Ni625 transition layer thickness of the product obtained in this embodiment was 0.5–0.6 mm, and the FeCoCrNiW... 0.4 Ta 0.4 The thickness of the high-entropy alloy working layer is 0.7–0.8 mm.

[0053] Example 3

[0054] This embodiment provides a method for preparing high-entropy alloy wear-resistant coatings by ultra-high-speed laser cladding, the steps of which are as follows:

[0055] S1. Preparation of high-entropy alloy powders. Fe, Co, Cr, Ni, W, and Ta metal powders with particle sizes of 20–53 μm were selected, specifically FeCoCrNiW. x Ta y The high-entropy alloy powder raw material, consisting of metals Fe, Co, Cr, Ni, W, and Ta, all with a purity greater than 99.9%, was weighed according to a molar ratio of Fe, Co, Cr, Ni, W, and Ta of 1:1:1:1:0.6:0.6 (in this example, x = 0.6, y = 0.6). The powder was then ground and mixed using a ball mill for 10 hours, using zirconia grinding beads with diameters of 10 mm, 5 mm, and 2 mm, at a speed of 200 r / min, to obtain FeCoCrNiW. 0.6 Ta 0.6 High-entropy alloy powder;

[0056] S2. 45# steel bar was selected as the experimental substrate, with a diameter of 50mm and a length of 500mm. Pretreatment was carried out: the surface oxide was removed with a grinding wheel, the substrate material was polished step by step with 200-600# sandpaper, the surface was cleaned with anhydrous ethanol, and then air-dried in an airy state.

[0057] S3. Under argon protection, a transition layer is prepared by cladding Ni625 alloy powder onto the surface of a substrate using an ultra-high-speed laser cladding process. The Ni625 alloy powder has been pre-dried in a vacuum drying oven at 100°C for 4 hours and loaded into a powder feeder. The key process parameters for ultra-high-speed laser cladding are as follows: laser spot diameter 2.2 mm, laser power: 3500 kW, linear velocity: 10 m / min, powder feed rate 42 g / min, feed rate: 1.1 mm / r, protective gas flow rate: 7.5 L / min, powder feeding gas flow rate: 17 L / min.

[0058] The transition layer surface is polished and cleaned, specifically: use a grinding wheel to remove the floating powder on the transition layer surface, polish it smooth, use 200-600# sandpaper to polish the transition layer, clean the surface with anhydrous ethanol, and let it air dry naturally.

[0059] S4. Under argon protection, using an ultra-high-speed laser cladding process, the FeCoCrNiW obtained in step S1 is clad... 0.6 Ta 0.6 FeCoCrNiW prepared by cladding high-entropy alloy powder on the surface of the transition layer 0.6 Ta 0.6 High-entropy alloy working layer, FeCoCrNiW 0.6 Ta 0.6 The high-entropy alloy powder has been pre-dried in a vacuum drying oven at 100℃ for 4 hours and loaded into the powder feeder. The key process parameters of ultra-high speed laser cladding are as follows: laser spot diameter 2.2mm, laser power: 4500kW, linear speed: 6m / min, powder feeding rate 40g / min, feed rate: 1.6mm / r, protective gas flow rate: 7.5L / min, powder feeding gas flow rate: 17L / min;

[0060] After the cladding is completed, the test bar is cooled to room temperature to obtain the product.

[0061] In this embodiment, the Ni625 transition layer thickness of the product is 0.5–0.6 mm, and the FeCoCrNiW content is... 0.6 Ta 0.6 The thickness of the high-entropy alloy working layer is 0.7–0.8 mm.

[0062] Comparative Example 1

[0063] This comparative example provides a method for preparing FeCoCrNiW using ultra-high-speed laser cladding. x A method for developing high-entropy alloy wear-resistant coatings, comparing the quality and performance of cladding coatings without the addition of Ta, specifically includes the following steps:

[0064] S1. Preparation of High-Entropy Alloy Powder. Fe, Co, Cr, Ni, and W metal powders with particle sizes of 20–53 μm were selected as raw materials for high-entropy alloy powder. The metal powders were weighed according to a molar ratio of 1:1:1:1:0.5 and ground and mixed using a ball mill for 9 hours. Zirconia ball mill beads with diameters of 10 mm, 5 mm, and 2 mm were used, and the ball mill speed was set to 200 r / min to form FeCoCrNiW. 0.5 High-entropy alloy powder;

[0065] S2. Select 45# steel bar as the experimental substrate, with a diameter of 50mm and a length of 500mm; remove the surface oxide with a grinding wheel, polish the substrate material with 200-600# sandpaper, clean the surface with anhydrous ethanol, and let it air dry naturally.

[0066] S3. Under argon protection, a transition layer is prepared by cladding Ni625 alloy powder onto the surface of a substrate using an ultra-high-speed laser cladding process. The Ni625 alloy powder has been pre-dried in a vacuum drying oven at 100°C for 4 hours and loaded into a powder feeder. The key process parameters for ultra-high-speed laser cladding are as follows: laser spot diameter 2.2 mm, laser power: 3500 kW, linear velocity: 10 m / min, powder feed rate 42 g / min, feed rate: 1.1 mm / r, protective gas flow rate: 7.5 L / min, powder feeding gas flow rate: 17 L / min.

[0067] The surface of the transition layer is polished and cleaned, specifically: use a grinder to remove the loose powder from the surface of the buffer layer, polish it smooth, use 200-600# sandpaper to polish the buffer layer, clean the surface with anhydrous ethanol, and let it air dry naturally.

[0068] S4. Under argon protection, using an ultra-high-speed laser cladding process, the FeCoCrNiW obtained in step S1 is clad... 0.5 FeCoCrNiW prepared by cladding high-entropy alloy powder on the surface of the transition layer 0.5 High-entropy alloy working layer, FeCoCrNiW 0.5 The high-entropy alloy powder has been pre-dried in a vacuum drying oven at 100°C for 4 hours and loaded into the powder feeder. The process parameters are set as follows: laser spot diameter 2.2 mm, laser power: 4100 kW, linear velocity: 8 m / min, powder feed rate 36 g / min, feed rate: 1.2 mm / r, protective gas flow rate: 7.5 L / min, and powder feeding gas flow rate: 17 L / min.

[0069] After the cladding is completed, the test bar is cooled to room temperature.

[0070] Measurements showed that the Ni625 transition layer thickness of the product prepared in this comparative example was 0.5–0.6 mm, and the FeCoCrNiW content was [missing information]. 0.5 The thickness of the high-entropy alloy working layer is 0.6–0.7 mm.

[0071] Comparative Example 2

[0072] Compared with Example 1, the difference in this comparative example is that step S3 is omitted, the buffer layer is not prepared, and FeCoCrNiW is directly applied to the surface of the 45# steel experimental shaft. 0.5 Ta 0.5 Preparation of high-entropy alloy working layer.

[0073] For the remaining parameters, conditions, and preparation process, refer to Implementation 1.

[0074] Performance testing

[0075] Microhardness testing of the cladding layer was conducted on Examples 1-3 and Comparative Examples 1-2. The testing method was as follows: a digital microhardness tester was used to measure the microhardness of different locations from the cladding layer to the substrate across the cross-section of the sample. During the measurement, a load of 1.96 N (HV0.2) was maintained for 15 s, and measurements were taken every 0.1 mm along the depth direction from approximately 0.1 mm above the cladding layer surface to the substrate. The highest hardness results for each sample are shown in Table 1.

[0076] Table 1 Hardness test data

[0077] Group Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Hardness / HV 961 872 987 822 954

[0078] Friction and wear tests were conducted on the cladding layers prepared in Examples 1-3 and Comparative Examples 1-2. At room temperature, an MDW-02 high-speed reciprocating friction and wear testing machine was used to rub the ultra-high-speed laser cladding coating against 360-mesh SiC sandpaper. Water was used as the lubricant, with a vertical load of 20 N, a reciprocating stroke of 30 mm, and a test frequency of 2 Hz. The sandpaper was replaced every 30 minutes during the test, for a total of 90 minutes. The results are shown in Table 2.

[0079] Table 2 Wear Measurement Data

[0080] Group Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Wear amount / g / h 0.0075 0.0081 0.0069 0.0105 0.0076

[0081] Non-destructive testing was performed on the cladding layers prepared in Examples 1-3 and Comparative Examples 1-2, and the results are shown in Table 3.

[0082] Table 3 Non-destructive testing

[0083]

[0084] Results analysis:

[0085] Figure 1 The image shows the morphology of the high-entropy alloy powder prepared in Example 1. The alloy powder is uniformly mixed, has high sphericity, and its particle size range is suitable for ultra-high-speed laser cladding.

[0086] The coating prepared by ultra-high speed laser cladding was sampled, ground, and polished, and the microstructure of the coating was analyzed by scanning electron microscopy. Figure 2 Microstructure diagram of the high-entropy alloy coating prepared in Example 1; from Figure 2 It can be seen that the high-entropy alloy cladding layer (working layer) exhibits a distinct eutectic structure, which is uniform and dense, and has good formability.

[0087] Figure 3The results of the microhardness test of the high-entropy alloy cladding layer prepared by ultra-high speed laser cladding in Example 1 are as follows: The microhardness of the high-entropy alloy cladding layer (working layer) in Example 1 can reach 961 HV, the transition layer is about 340 HV, and the substrate is about 200 HV. The hardness of the high-entropy alloy working layer is about 3.5 times higher than that of the substrate. The buffer layer can play a good role in hardness buffering and reduce the tendency of the cladding layer to crack.

[0088] The hardness test results of Examples 1-3 and Comparative Examples 1-2 are shown in Table 1. The coatings of Examples 1, 3 and Comparative Example 2 have relatively high hardness. The hardness of Examples 2 and Comparative Example 1 is significantly reduced when the molar proportion of W and Ta in the high-entropy alloy is reduced. The addition of W and Ta has a significant effect on the hardness of the cladding layer.

[0089] As can be seen from Tables 1 and 2, the high-entropy alloy coating material obtained by ultra-high speed laser cladding in this invention has high hardness and excellent wear resistance. The non-destructive testing results of the cladding coating show that fine cracks appeared in Example 3 and long strip-shaped open cracks appeared in Comparative Example 2, which verifies that the addition of Ta element and buffer layer can effectively reduce the crack sensitivity of the cladding layer.

[0090] In summary, the method for preparing high-entropy alloy wear-resistant coatings by ultra-high-speed laser cladding described in this invention can obtain high-hardness and high-wear-resistant high-entropy alloy coatings, promoting the development and application of high-entropy alloys in materials coating engineering.

[0091] Although some preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the invention.

[0092] Those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this application and their equivalents, this invention is also intended to include these modifications and variations.

Claims

1. A method for preparing high-entropy alloy wear-resistant coatings by ultra-high-speed laser cladding, characterized in that, Includes the following steps: S1, according to the target alloy FeCoCrNiW x Ta y The designed component is taken as metal powder Fe, Co, Cr, Ni, W and Ta, wherein x, y are molar ratios, 0.4≤x≤0.6, 0.4≤y≤0.6, and FeCoCrNiW is prepared by ball milling mixing x Ta y High-entropy alloy powder; S2. Pre-treat the surface of the substrate; S3. Using ultra-high-speed laser cladding technology, Ni625 alloy powder is clad onto the surface of the substrate to prepare a transition layer, and the surface of the transition layer is polished and cleaned. S4. Employing ultra-high-speed laser cladding technology, FeCoCrNiW x Ta y A working layer is prepared by cladding high-entropy alloy powder on the surface of the transition layer to obtain the finished product.

2. The method as described in claim 1, characterized in that, In step S1, the particle sizes of the metal powders Fe, Co, Cr, Ni, W, and Ta are all 20~53 μm, and they are ball-milled and mixed for 10~24 h to obtain FeCoCrNiW. x Ta y High-entropy alloy powder.

3. The method as described in claim 1, characterized in that, In step S2, the pretreatment includes: removing surface oxides with a grinding wheel, sanding the substrate with sandpaper, and cleaning the surface with anhydrous ethanol.

4. The method as described in claim 1, characterized in that, In step S3, the ultra-high-speed laser cladding process parameters include: The laser spot diameter is 2~3mm, the laser power is 3300~4000kW, the linear velocity is 10~20 m / min, the powder feed rate is 40~50g / min, the feed rate is 1~1.3 mm / r, the protective gas flow rate is 7~10L / min, and the powder feeding gas flow rate is 15~20L / min.

5. The method as described in claim 1, characterized in that, In step S3, the Ni625 alloy powder has a particle size of 20~53μm and the transition layer has a thickness of 0.5mm~0.8mm.

6. The method as described in claim 1, characterized in that, In step S3, the polishing and cleaning process includes: removing the floating powder on the surface of the Ni625 transition layer with a grinding wheel, polishing it smooth, polishing the Ni625 transition layer with sandpaper, and cleaning the surface with anhydrous ethanol.

7. The method as described in claim 1, characterized in that, In step S4, the ultra-high-speed laser cladding process parameters include: The laser spot diameter is 2~3mm, the laser power is 4000~4500kW, the linear speed is 6~15m / min, the powder feeding rate is 30~40g / min, the feed rate is 1.2~1.6 mm / r, the protective gas flow rate is 7~10L / min, and the powder feeding gas flow rate is 15~20L / min.

8. The method as described in claim 1, characterized in that, In step S4, the thickness of the working layer is 0.6 mm to 1 mm.

9. A high-entropy alloy wear-resistant coating, characterized in that, The high-entropy alloy wear-resistant coating prepared by the method of any one of claims 1 to 8 comprises a transition layer on the surface of the substrate and a working layer on the surface of the transition layer. The transition layer is formed by Ni625 alloy powder on the surface of the substrate using an ultra-high-speed laser cladding process. The working layer is made of FeCoCrNiW x Ta y High-entropy alloy powder was prepared on the surface of the transition layer using an ultra-high-speed laser cladding process. The chemical formula is FeCoCrNiW. x Ta y In the equation, x and y are molar ratios, where 0.4 ≤ x ≤ 0.6 and 0.4 ≤ y ≤ 0.

6.

10. The high-entropy alloy wear-resistant coating as described in claim 9, characterized in that, The thickness of the transition layer is 0.5mm to 0.8mm, and the thickness of the working layer is 0.6mm to 1mm.

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