A wear-resistant cobalt-based cladding powder, an ultra-fine lamellar eutectic cobalt-based coating and a preparation method

Abstract

The application discloses an anti-abrasion cobalt-based cladding powder, an ultrafine lamellar eutectic cobalt-based coating and a preparation method, and belongs to the technical field of anti-abrasion and anticorrosion alloy coating. The cladding powder comprises 15.0-20.0% of Ni, 14.0-15.0% of Cr, 22.0-25.0% of Mo, 2.7-2.9% of Si and 0.07% or less of C, and the rest is Co, in percentage by mass. The application utilizes the difference in mixing enthalpy of a specific content of Ni element and other elements in the cobalt-based alloy system, changes the non-equilibrium solidification path in laser cladding, suppresses the excessive precipitation and growth of Laves phase, and forms a Laves phase / (gamma-Co / Ni) lamellar ultrafine eutectic structure with excellent strength and toughness. Compared with the prior art, the application can significantly reduce the crack sensitivity of the coating without sacrificing the comprehensive performance of the coating in abrasion resistance and corrosion resistance.

Description

Technical Field

[0001] This invention relates to the field of wear-resistant and corrosion-resistant alloy coating technology, and in particular to a Co-based wear-resistant and corrosion-resistant alloy coating based on the characteristics of Laves phase / (γ-Co / Ni) ultrafine eutectic structure and its preparation method. Background Technology

[0002] In aerospace engines, petrochemicals, metallurgy, and power industries, hot-end components are subjected to high-temperature wear and corrosion, and surface protection is typically achieved using Tribaloy series cobalt-based alloy coatings. Co-based alloys, such as T800 and T400, improve the alloy's hardness and wear resistance by forming approximately 50% blocky Mo and Si-rich Laves hard phases within a well-formed γ-Co-based solid solution. The Laves phases strengthen the alloy, enhancing its hardness and wear resistance.

[0003] However, this type of cobalt-based alloy has significant drawbacks: the formation of a large number of coarse Laves phases in the alloy greatly increases the crack susceptibility of Tribaloy alloys and the complexity of coating preparation processes. For example, the T-800 alloy coating is prepared using a laser cladding process, which typically requires preheating the workpiece to above 660°C and then slowly cooling it in a furnace after cladding to effectively prevent crack formation. This process is extremely difficult, and the excessively high preheating temperature also deteriorates the production environment.

[0004] Current improvements to Co-based high-temperature wear-resistant and corrosion-resistant alloys mostly involve replacing expensive Co with low-cost alloying elements. For example, patent ZL202210108505.4 discloses a multi-principal element wear-resistant and corrosion-resistant alloy and its preparation method based on Laves phase reinforcement. This method uses a Co-Cr-Fe-Ni multi-principal element solid solution to replace the Co-based solid solution matrix, with Mo and Si forming a hard, wear-resistant Laves phase. This achieves high wear resistance and corrosion resistance while reducing material brittleness and saving raw material costs, making it particularly suitable for applications requiring wear resistance in high-temperature and corrosive working environments. Another example is invention patent ZL201811384526.9, which discloses an iron-based alloy and its preparation method based on Laves phase reinforcement to resist molten zinc corrosion. By replacing Co with inexpensive Fe, a wear-resistant and corrosion-resistant alloy material with Laves as the reinforcing phase and α-Fe as the matrix is ​​obtained. The aforementioned inventions all achieved a microstructure similar to T-800, namely, a large number of coarse, blocky Laves phases distributed within a more ductile alloy phase. While this improves wear and corrosion resistance, the interface between the coarse Laves phases and the alloy phases is prone to localized stress concentration, inducing interfacial cracking. The high crack sensitivity of the alloy material remains a problem. This limits the application of this type of alloy to some extent, especially as a coating material in laser cladding or plasma cladding processes.

[0005] Therefore, it is necessary to study a new type of wear-resistant and corrosion-resistant alloy material with similar performance to T-800 alloy, but with low crack sensitivity and good cladding processability, so as to solve the pain points of traditional coatings being prone to cracking and complex processing procedures. Summary of the Invention

[0006] To overcome the limitations of traditional Tribaloy series cobalt-based alloy coatings that rely on high Mo and Si content to precipitate large amounts of coarse, blocky Laves hard phases to improve hardness and wear resistance, and to address the cumbersome process of preheating the workpiece at high temperatures and then slowly cooling it in a furnace after cladding to suppress crack formation, this invention provides a wear-resistant cobalt-based cladding powder, a cobalt-based alloy coating made from this powder, and a method for preparing the coating.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A wear-resistant cobalt-based cladding powder, characterized in that, by mass percentage, its composition is as follows: Ni 15-20%, Cr 14-15%, Mo 22-25%, Si 2.7-2.9%, C < 0.07%, with the balance being Co; wherein, Co, Cr, and Ni elements together form a γ-Co / Ni solid solution matrix, and Mo and Si elements form a Laves phase; the Ni element is used to regulate the solidification structure and significantly suppress the formation of coarse, blocky Laves phase.

[0009] A wear-resistant cobalt-based alloy coating with an ultrafine eutectic structure is characterized in that it is formed by cladding with the aforementioned wear-resistant cobalt-based cladding powder; the microstructure of the coating mainly consists of lamellar Laves hard phase and lamellar γ-Co / Ni solid solution growing alternately to form a lamellar eutectic structure. When the nickel content is 20 wt.%, the coating has no coarse primary Laves phase; when the nickel content is 15 wt.%, the matrix is ​​still dominated by lamellar eutectic, with only a small amount of coarse, petal-shaped Laves phase present locally.

[0010] Furthermore, the γ-Co / Ni solid solution has a face-centered cubic structure.

[0011] Furthermore, in the microstructure of the alloy coating, the volume fraction of the γ-Co / Ni solid solution is 55.0%-70.0%, and the volume fraction of the Laves phase is 30.0%-45.0%.

[0012] Furthermore, the thickness of both the γ-Co / Ni solid solution and the Laves hard phase layer is in the submicron range.

[0013] The method for preparing the wear-resistant cobalt-based alloy coating with an ultrafine eutectic structure provided by the present invention is characterized by comprising the following steps:

[0014] S1, Powder mixing: Weigh the metal powders of each element according to the set alloy composition ratio, mechanically mix them to obtain uniform alloyed powder, and then dry the alloyed powder.

[0015] S2, Substrate pretreatment: Sandblast the surface of the substrate to be treated to remove oxide scale and oil stains, use ultrasonic cleaning and dry in a vacuum drying oven;

[0016] S3, Laser cladding: Under a protective atmosphere, the mixed powder obtained in step S1 is melted and deposited on the surface of the substrate using a laser cladding process, and after solidification, a wear-resistant cobalt-based alloy coating is formed.

[0017] Furthermore, in step S1, the alloy powders of each element are all spherical gas-atomized powders with a particle size range of 50-150 μm. They are mixed for 4-6 hours at a speed of 200-300 r / min under inert gas protection using a planetary ball mill, and then kept at 100°C for 24 hours in a vacuum drying oven to ensure complete drying.

[0018] Furthermore, during the laser cladding process, a grating-type scanning method is used for synchronous powder feeding.

[0019] Furthermore, the laser cladding process parameters are as follows: laser power is 2-2.5 kW, scanning speed is 8-12 mm / s, powder feeding rate is 8-12 g / min, and the overlap rate of multi-pass cladding is set to 40%-60%.

[0020] It should be noted that this invention is not limited to laser cladding. Plasma cladding can be used to replace laser cladding. Under the conditions of matching the corresponding low heat input and fast scanning process parameters, it is also possible to achieve non-equilibrium rapid solidification of alloys and obtain an ultrafine lamellar eutectic structure without coarse primary Laves phase.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] First, this invention alters the non-equilibrium solidification and crystallization path by introducing a specific proportion of Ni (15-20 wt.%) into the alloy system. Due to the large absolute value of the mixing enthalpy between Ni and Mo, a kinetic dragging effect is generated in the laser molten pool, trapping Mo atoms that tend to agglomerate towards the Laves phase nucleation region. Simultaneously, the primary temperature range of the Laves phase is significantly compressed. Combined with the extremely high cooling rate of the millisecond-level ultrafast solidification conditions unique to laser cladding, the formation of coarse, bulky Laves phases is greatly suppressed, and the microstructure is reshaped into a strong and tough lamellar eutectic structure.

[0023] Second, this invention significantly reduces the crack susceptibility of alloy coatings with similar compositions. The face-centered cubic γ-Co / Ni solid solution in the microstructure endows the coating with excellent local plastic deformation capability. Faced with the residual tensile stress generated during laser cladding, when cracks pass through the soft and tough phase lamellars, plastic rheology is induced through dislocation proliferation, a large number of stacking faults, and crystallographic slip, effectively blunting the crack tip and dissipating strain energy, successfully reducing the crack susceptibility to 0, and achieving defect-free cladding forming under preheating conditions.

[0024] Third, this invention maintains and optimizes the overall tribological service performance of the coating. Although the reduction in the volume fraction of the hard Laves phase leads to a moderate decrease in macroscopic and microscopic hardness, the densely alternating submicron-scale eutectic phase interfaces exhibit a strong interface strengthening effect (Hall-Petch effect) by hindering dislocation slip, thus coordinating the plastic deformation of the soft and hard phases. Simultaneously, the Ni / Co-rich composite oxide film provides solid lubrication, resulting in a significant reduction in the average coefficient of friction and a substantial improvement in service stability.

[0025] In summary, this invention, by synergistically limiting the proportions of Ni, Cr, Mo, and Si, and by controlling the thermodynamic and kinetic behavior of non-equilibrium solidification during the cladding process with a specific Ni content, suppresses the precipitation of coarse, blocky primary Laves phase, thereby obtaining a submicron-scale Laves phase / (γ-Co / Ni) lamellar ultrafine eutectic structure. Relying on the interfacial strengthening effect of the numerous phase interfaces of the ultrafine eutectic and the toughening effect of the plastic γ-Co / Ni solid solution, while ensuring that the overall wear and corrosion resistance of the coating is comparable to that of commercial T-800 alloy, it significantly reduces the crack sensitivity of the coating, achieves preheating-free cladding forming, and simplifies the preparation process. Attached Figure Description

[0026] Figure 1. Morphology of the ultrafine lamellar eutectic structure of the wear-resistant cobalt-based alloy coating in Example 1 of the present invention; wherein (a) is a scanning electron microscope (SEM) morphology image; and (b) is a transmission electron microscope (TEM) morphology image.

[0027] Figure 2 The X-ray diffraction pattern of the wear-resistant cobalt-based alloy coating provided in Embodiment 1 of the present invention.

[0028] Figure 3 This is a scanning electron microscope image of the ultrafine lamellar eutectic structure of the wear-resistant cobalt-based alloy coating in Example 2 of the present invention.

[0029] Figure 4 The image shows the scanning electron microscope (SEM) morphology of the ultrafine lamellar eutectic structure of the wear-resistant cobalt-based alloy coating in Comparative Example 1.

[0030] Figure 5 The image shows the scanning electron microscope (SEM) morphology of the ultrafine lamellar eutectic structure of the wear-resistant cobalt-based alloy coating in Comparative Example 2.

[0031] Figure 6 The phase fraction-temperature thermodynamic curves are for the T-800 coating and the coating of Example 1 of the present invention, where (a) is the T-800 coating and (b) is the coating of Example 1. Detailed Implementation

[0032] The technical solution of the present invention will be further described below with reference to the accompanying drawings. It should be understood that the following embodiments are only used to illustrate the present invention and are not intended to limit the scope of protection of the present invention.

[0033] Example 1:

[0034] This embodiment provides a wear-resistant cobalt-based alloy coating with an ultrafine eutectic structure. The volume fraction of the γ-Co / Ni solid solution phase in the coating is 59.6%, and the volume fraction of the Laves phase is 40.4%. Its target composition, by mass fraction, is: 20.00% Ni, 14.00% Cr, 22.80% Mo, 2.72% Si, <0.06% C, with the balance being Co.

[0035] The preparation steps are as follows:

[0036] Step S1, Powder Mixing: Prepare spherical gas-atomized elemental metal powders of each element separately, with the powder particle size uniformly controlled between 50 and 150 μm; weigh the corresponding gas-atomized spherical metal powders according to the proportion, then place them in a sealed container and mix them in a three-dimensional mixer for 5 hours, then transfer them to a planetary ball mill, introduce argon gas for protection, and ball mill at a speed of 200-300 r / min for 5 hours to obtain uniform mechanical alloyed powder, and finally transfer it to a vacuum drying oven for thorough drying.

[0037] Step S2, substrate pretreatment: The 1020 low carbon steel substrate with dimensions of 150mm×100mm×15mm is sandblasted to remove oxide scale and oil stains, then ultrasonically treated in anhydrous ethanol and dried in a vacuum drying oven for later use.

[0038] Step S3, Laser Cladding: In this embodiment, an RFL-6000-CL laser is used, employing synchronous powder feeding combined with a grating scanning process. High-purity argon gas (flow rate 8 L / min) is used as the protective gas to deposit the mechanically alloyed powder obtained in step S1 layer by layer onto the substrate surface, thus obtaining the target cobalt-based alloy coating. The parameters are set as follows: laser power 2 kW, scanning speed 10 mm / s, powder feeding rate 10 g / min, and multi-channel scanning overlap rate 50%. Finally, the desired result is... Figure 1 The coating has the microstructure shown.

[0039] The cobalt-based alloy coating prepared in Example 1 was subjected to microstructure observation, hardness testing, and room temperature dry sliding friction and wear performance testing. The test results showed that the bulky primary Laves phase in the coating completely disappeared, and the microstructure evolved into a fine lamellar eutectic structure of Laves phase / (γ-Co / Ni) phase. The coating had zero crack sensitivity, and the lamellar thickness was only 400-500 nm. The coating was well-formed, with a dense, smooth, and crack-free surface, and its average microhardness was 674.4 HV. 0.3 The room temperature dry sliding friction test showed that the wear rate was 1.187 × 10⁻⁶. -5 mm 3 ·N -1 ·m -1 The average friction coefficient was significantly reduced to 0.3648 compared to 0.4758 for the T-800 coating prepared by the same process, and it tended to stabilize.

[0040] As can be seen from the X-ray diffraction pattern shown in Figure 2, the coating obtained in Example 1 contains only the Laves hard phase and the γ-Co / Ni solid solution phase.

[0041] Example 2:

[0042] This embodiment provides a wear-resistant cobalt-based alloy coating with an ultrafine eutectic structure. The volume fraction of the γ-Co / Ni solid solution phase in the coating is 68.6%, and the volume fraction of the Laves phase is 31.4%. The target composition, by mass fraction, is: 15.00% Ni, 14.88% Cr, 24.23% Mo, 2.89% Si, <0.07% C, with the balance being Co.

[0043] The preparation process is completely consistent with that in Example 1, and the final result is... Figure 3 The coating has the microstructure shown.

[0044] The coating obtained in Example 2 was tested using the same characterization and testing methods as in Example 1. The test results showed that the coating microstructure transitioned from a coarse petal-like structure to a short rod-shaped Laves phase and eutectic structure. The average hardness of the coating was 712.9 HV0.3, and the crack sensitivity was significantly reduced to only 0.1164. The number of macroscopic cracks on the coating surface was sharply reduced, and the number of penetrating transverse cracks was significantly decreased. Residual stress and crack propagation assessments showed that, compared to the macroscopic penetrating transverse cracks in the comparative example T-800 coating, the crack tip in Example 2 initiated significant microscopic plastic rheology and dislocation entanglement when penetrating the soft and ductile Ni-rich lamellar, causing a reversal and allowing stress to be safely dissipated, thus inhibiting crack propagation. However, due to the still small amount of coarse petal-like Laves phase present, its tribological properties were inferior to those of Example 1.

[0045] To highlight the influence of the Ni content range defined in this invention and the synergistic matching relationship between Ni, Mo, and Si on the coating microstructure, crack sensitivity, and tribological properties, two sets of comparative experiments were conducted. Both sets of comparative sample samples used the same cladding preparation process as the examples, but the Ni content in their alloy powders exceeded the range defined in this invention, and the Cr, Mo, and Si components simultaneously deviated from the designed proportions. The alloy powder proportions of the examples and the two comparative sets are shown in Table 1.

[0046] Comparative Example 1:

[0047] The target composition of the alloy coating provided in this comparative example, by mass percentage, is: 5.00% Ni, 16.63% Cr, 27.08% Mo, 3.23% Si, <0.07% C, with the balance being Co. The final result was obtained using a preparation process completely consistent with Example 1. Figure 4 The coating has the microstructure shown.

[0048] The coating prepared in Comparative Example 1 was tested using the same characterization and testing methods as in Example 1. The test results showed that, similar to Example 2, the coating microstructure transitioned from coarse petal-like to short rod-like Laves phase and eutectic structure; the average microhardness of the coating was 737.4 HV0.3, and the crack sensitivity was as high as 0.7395. Although the number of macroscopic cracks on the coating surface was slightly reduced, a large number of transverse and longitudinal cracks were still distributed. Although the lower Ni content slightly reduced the coating wear rate, the coating retained a large number of coarse, petal-like, hard and brittle Laves phases, resulting in a higher coefficient of friction and a tendency for cracking failure. Overall, its tribological service performance was inferior to that of Examples 1 and 2, and its performance also failed to meet the key performance requirement of the coating of this invention—low crack sensitivity.

[0049] Comparative Example 2:

[0050] The target composition of the alloy coating provided in this comparative example, by mass percentage, is: 25.00% Ni, 13.13% Cr, 21.38% Mo, 2.55% Si, <0.06% C, with the balance being Co. The preparation process is completely consistent with Example 1, and the microstructure of the resulting coating is shown in [Figure 1]. Figure 5 .

[0051] The coating prepared in Comparative Example 2 was tested using the same characterization and testing methods as in Example 1. The test results showed that the coating microstructure had changed significantly; the matrix phase was a γ-Co / Ni solid solution phase, and the Laves phase precipitated as a minor precipitate along the grain boundaries. Although no cracks were observed in the coating, the average microhardness decreased significantly to 581.4 HV0.3, the average coefficient of friction reached 0.3956, and the wear rate increased significantly to 1.728 × 10⁻⁶. -5 mm 3 ·N-1 ·m -1 Its performance has deviated from the basic performance required for the coating of this invention - wear resistance.

[0052] Table 1 compares the coating performance of Examples 1-2, Comparative Examples 1-2, and commercial T-800 powder prepared using the same laser cladding process. The table shows that while the commercial T-800 coating has a low wear rate, it is extremely susceptible to cracking, easily developing cracks and peeling off completely during service. The cobalt-based alloy coating of this invention has a lower and more stable coefficient of friction. Example 1, with nickel content at the upper limit of the range, shows no crack initiation, and Example 2, with nickel content at the lower limit of the range, also exhibits significantly lower crack sensitivity than the commercial T-800. Overall, its friction conditions are more stable than T-800, resulting in superior long-term wear resistance and reliability.

[0053] Comparing the test data of the two sets of embodiments, it can be seen that the microhardness, average friction coefficient, and wear rate of Embodiment 1 are all lower than those of Embodiment 2, and the overall performance is better than that of Embodiment 2. This indicates that during solidification, as the Ni content increases, the liquidus temperature of the alloy system decreases, the primary temperature range of the Laves phase is compressed, and the molten pool crosses the primary temperature range and enters the eutectic growth region under rapid cooling, forming a eutectic structure with a lamellar thickness on the submicron level. When the Ni content is at the upper limit of the composition range of this invention, the coating microstructure is mainly composed of lamellar Laves hard phase and lamellar γ-Co / Ni solid solution, which can completely eliminate the blocky primary Laves phase. Figure 1 (a) shows a low-magnification electron microscope image, revealing that the coating exhibits a uniform microstructure throughout, without any coarse, blocky primary Laves phase. Figure 1 (b) is a high-magnification electron microscope image, showing alternating lamellar Laves hard phases and lamellar γ-Co / Ni solid solutions, with lamellar thicknesses only on the submicron scale. Figure 6 The phase fraction-temperature thermodynamic curves shown fully corroborate the above-described eutectic growth process. (Comparison) Figure 6 (a) T-800 coating and Figure 6 (b) As can be seen from the phase transformation law of the coating in Example 1 of the present invention, the Ni content can be adjusted to compress the precipitation temperature range of the primary Laves phase, and promote the direct entry of the two-phase eutectic transformation when the molten pool cools. This explains the intrinsic mechanism of the coating without coarse blocky primary Laves phase and forming a uniform submicron lamellar eutectic structure from a thermodynamic perspective.

[0054] Comparative analysis of experimental data from the examples and comparative examples shows that when the Ni content is below the lower limit of this invention by 15 wt.%, and the Cr, Mo, and Si ratios simultaneously exceed the design range, a large number of coarse, blocky Laves phases are generated inside the coating, significantly increasing crack sensitivity and making it extremely prone to cracking and failure during service. When the Ni content is above the upper limit of this invention by 20 wt.%, and the Cr and Si ratios simultaneously fall below the design range, the precipitation of hard Laves phases is insufficient, and the coating hardness and wear resistance decrease significantly. The above results demonstrate that only by strictly adhering to the Ni, Cr, Mo, and Si ratios defined by this invention can a fine lamellar eutectic structure be obtained. Even though appropriately reducing the Mo and Si content in the coating alloy powder of this invention reduces Laves phase precipitation and weakens the contribution of hard phases to relative hardness, a large number of fine phase interfaces can achieve interface strengthening, and the dense eutectic interfaces can disperse the concentrated stress of the two phases. Combined with the toughening effect of the plastic γ-Co / Ni solid solution, a comprehensive performance balance of excellent strength and toughness, low crack sensitivity, and high wear resistance is achieved.

[0055]

[0056] Furthermore, for surface strengthening applications of large industrial valve components, the coating of this invention can also be prepared using plasma cladding. Plasma cladding offers high energy density, enabling reliable metallurgical bonding between the coating and the substrate, and boasts excellent welding efficiency, making it suitable for the batch strengthening needs of large components. Its powder mixing and substrate pretreatment processes are consistent with the aforementioned laser cladding embodiments, eliminating the need for high-temperature preheating of the substrate and allowing direct deposition of alloy powder onto the substrate surface. However, strict control of heat input is required when using plasma cladding. Exemplary process parameters are set as follows: transfer arc current 80-150 A, non-transfer arc current 30-50 A, plasma arc scanning speed 3-8 mm / s, and powder feed rate 10-20 g / min. Through this combination of parameters matching low heat input and rapid movement, plasma cladding can also achieve a high-toughness Laves phase / (γ-Co / Ni) lamellar eutectic structure, significantly reducing the coating's crack sensitivity.

[0057] The above are merely preferred embodiments of the present invention and are not intended to limit the technical solutions of the present invention. Any modifications or simple alterations made to the technical solutions of the present invention without creative effort should be within the scope of protection of the present invention, specifically as defined in the claims.

Claims

1. A wear-resistant cobalt-based cladding powder, characterized in that, The composition by mass percentage is as follows: Ni 15-20%, Cr 14-15%, Mo 22-25%, Si 2.7-2.9%, C < 0.07%, with the balance being Co; wherein, Co, Cr, and Ni elements together form a γ-Co / Ni solid solution matrix, and Mo and Si elements form a Laves phase; the Ni element is used to regulate the solidification structure and significantly suppress the formation of coarse, blocky Laves phase.

2. A wear-resistant cobalt-based alloy coating with an ultrafine eutectic structure, characterized in that, It is formed by cladding with the wear-resistant cobalt-based cladding powder as described in claim 1; the microstructure of the coating is mainly composed of lamellar Laves hard phase and lamellar γ-Co / Ni solid solution growing alternately to form a lamellar eutectic structure.

3. The wear-resistant cobalt-based alloy coating with an ultrafine eutectic structure as described in claim 2, characterized in that, The γ-Co / Ni solid solution has a face-centered cubic structure.

4. The wear-resistant cobalt-based alloy coating with an ultrafine eutectic structure as described in claim 2, characterized in that, In the microstructure of the alloy coating, the volume fraction of the γ-Co / Ni solid solution is 55.0%-70.0%, and the volume fraction of the Laves phase is 30.0%-45.0%.

5. The wear-resistant cobalt-based alloy coating with an ultrafine eutectic structure as described in claim 2, characterized in that, The thickness of both the γ-Co / Ni solid solution and the Laves hard phase layer is in the submicron range.

6. A method for preparing a wear-resistant cobalt-based alloy coating with an ultrafine eutectic structure as described in any one of claims 2-5, characterized in that, Includes the following steps: S1, Powder mixing: Weigh the metal powders of each element according to the set alloy composition ratio, mechanically mix them to obtain uniform alloyed powder, and then dry the alloyed powder. S2, Substrate pretreatment: Sandblast the surface of the substrate to be treated to remove oxide scale and oil stains, use ultrasonic cleaning and dry in a vacuum drying oven; S3, Laser cladding: Under a protective atmosphere, the mixed powder obtained in step S1 is melted and deposited on the surface of the substrate using a laser cladding process, and after solidification, a wear-resistant cobalt-based alloy coating is formed.

7. The method for preparing a wear-resistant cobalt-based alloy coating with an ultrafine eutectic structure as described in claim 6, characterized in that, In step S1, the alloy powders of each element are spherical gas atomized powders with a particle size range of 50-150 μm. They are mixed for 4-6 hours at a speed of 200-300 r / min under inert gas protection using a planetary ball mill, and then kept at 100°C for 24 hours in a vacuum drying oven to ensure complete drying.

8. The method for preparing a wear-resistant cobalt-based alloy coating with an ultrafine eutectic structure as described in claim 6, characterized in that, During laser cladding, grating scanning is performed using synchronous powder feeding.

9. The method for preparing a wear-resistant cobalt-based alloy coating with an ultrafine eutectic structure as described in claim 8, characterized in that, The laser cladding process parameters are as follows: laser power is 2-2.5 kW, scanning speed is 8-12 mm / s, powder feeding rate is 8-12 g / min, and the overlap rate of multi-pass cladding is set to 40%-60%.

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