A co cr ni-tic composite coating and a preparation method thereof

Abstract

The present application relates to a kind of CoCrNi-TiC composite coating and its preparation method, belong to coating technical field.The preparation method of the present application includes the following steps: S1, CoCrNi alloy powder and TiC particle are mixed, to obtain composite powder;S2, by laser cladding technology, CoCrNi alloy powder, composite powder are alternately made CoCrNi alloy layer and CoCrNi-TiC composite layer on metal substrate, to obtain CoCrNi-TiC composite coating;Wherein, directly prepared on the surface of metal substrate is CoCrNi alloy layer, the layer number of CoCrNi alloy layer and CoCrNi-TiC composite layer is 4-6 layers.Through the combination of TiC and CoCrNi and thin thick alternating structure design, the optimization of CoCrNi-TiC composite coating in hardness, wear resistance, toughness, thermal shock resistance and fatigue resistance etc.Aspects are realized, further improve the performance of CoCrNi-TiC composite coating under complex working condition.

Description

Technical Field

[0001] This invention belongs to the field of coating technology, and particularly relates to a CoCrNi-TiC composite coating and its preparation method. Background Technology

[0002] Existing surface strengthening technologies, such as heat treatment and spraying, while improving the hardness and wear resistance of materials, often fail to simultaneously meet multiple requirements such as high wear resistance, corrosion resistance, and toughness. Laser cladding technology, due to its ability to precisely control the composition and structure of the cladding layer, has become an effective surface treatment method. However, current laser cladding technologies mostly focus on reinforcing single materials, lacking precise control over the compositional gradient of composite materials. CoCrNi-TiC composites are widely used due to their excellent properties, but traditional methods for preparing metal matrix composites have certain problems regarding compositional uniformity and interlayer bonding strength.

[0003] One issue is coating brittleness: In some cases, especially when the coating contains a high proportion of hard particles such as TiC, the brittleness of the laser-clad coating increases due to thermal stress concentration or grain coarsening. This makes the coating more prone to cracking or peeling when subjected to loads such as impact and vibration, affecting its durability and reliability.

[0004] Secondly, there is the issue of the heat-affected zone: Although the heat-affected zone of laser cladding technology is smaller than that of other heat treatment methods, the temperature in some local areas is still relatively high under high-power laser irradiation. This heat effect may cause deformation and reduced hardness of the substrate material, and may even affect the microstructure of the substrate material. In particular, for some heat-sensitive materials (such as aluminum alloys and titanium alloys), it will reduce the overall performance of the substrate.

[0005] Third, the adhesion between the coating and the substrate is not ideal: Although laser cladding can achieve metallurgical bonding between the coating and the substrate, the uneven composition ratio, excessively thin or thick cladding layer result in poor adhesion between the cladding layer and the substrate, which easily leads to delamination during use and affects the service life of the material.

[0006] Fourthly, there is the issue of coating thickness and uniformity: Traditional laser cladding technology relies on the adjustment of laser parameters and scanning path to control the coating thickness, which often makes it difficult to ensure uniform coating thickness. Especially on complex or large-area surfaces, uneven coating, weak bonding of the cladding layer, and inconsistent thickness in some areas may occur, which can easily lead to cracks or interlayer peeling, and also affect the performance of the coating, such as wear resistance and corrosion resistance.

[0007] Fifth, there is the paradox between strength and plasticity: In traditional CoCrNi-TiC composite coatings, a higher TiC content helps improve hardness and wear resistance, but an excessively high TiC content leads to increased brittleness, thus affecting its impact resistance and toughness. This performance conflict means that in certain applications, composite coatings with a single component or a fixed ratio cannot simultaneously meet multiple performance requirements.

[0008] Sixth, surface properties are insufficient to meet the requirements of multiple working conditions: Most existing laser cladding technologies focus on surface strengthening of a single material. Although they can improve surface hardness and wear resistance, they cannot simultaneously optimize multiple properties such as wear resistance, corrosion resistance, and toughness. Under extreme working conditions, although the material surface has high hardness, it may suffer from brittle fracture or insufficient impact resistance.

[0009] Therefore, how to optimize the overall performance of CoCrNi-TiC composite coatings through laser cladding process remains a pressing problem to be solved. Summary of the Invention

[0010] To address the aforementioned technical problems, this invention provides a CoCrNi-TiC composite coating and its preparation method. By combining TiC and CoCrNi and employing an alternating thin-thickness structure design, the CoCrNi-TiC composite coating achieves optimization in terms of hardness, wear resistance, toughness, thermal shock resistance, and fatigue resistance, further improving its performance under complex working conditions.

[0011] The first objective of this invention is to provide a CoCrNi-TiC composite coating and its preparation method, comprising the following steps:

[0012] S1. Mix CoCrNi alloy powder and TiC particles to obtain composite powder;

[0013] S2. Using laser cladding technology, CoCrNi alloy powder and composite powder are alternately used to form CoCrNi alloy layers and CoCrNi-TiC composite layers on a metal substrate to obtain the CoCrNi-TiC composite coating; wherein, the CoCrNi alloy layer is directly prepared on the surface of the metal substrate, and the number of layers of both the CoCrNi alloy layer and the CoCrNi-TiC composite layer is 4-6.

[0014] In one embodiment of the present invention, in S1, the mass ratio of Co, Cr and Ni in the CoCrNi alloy powder is (34-36):(32-34):(31-33).

[0015] In one embodiment of the present invention, in S1, the CoCrNi alloy powder has a particle size of 50μm-150μm to ensure good cladding performance and adhesion; the TiC particles have a particle size of 28μm-50μm and serve as a reinforcing phase to improve the wear resistance of the composite coating. TiC is a ceramic material with extremely high hardness, and its addition to the CoCrNi alloy matrix can significantly improve the hardness and wear resistance of the composite coating. As a hard reinforcing phase, TiC particles can prevent wear particles from eroding the CoCrNi alloy matrix, thereby reducing wear. The reinforcing effect of TiC particles enables the CoCrNi alloy matrix to effectively resist wear in a wear environment. In addition, by adjusting the mass fraction of TiC particles and the thickness of the CoCrNi-TiC composite layer, wear resistance can be optimized without causing brittleness problems due to excessive hardness.

[0016] In one embodiment of the present invention, in S1, the mass percentage of TiC particles in the composite powder is 5%-25%, ensuring that the material maintains sufficient hardness while also possessing high toughness and crack resistance.

[0017] In one embodiment of the present invention, in step S2, the process parameters of the laser cladding technology are as follows: laser power of 2300W-3000W, scanning speed of 6mm / s-10mm / s, powder feed rate of 2.5r / min-4.0r / min, and laser beam diameter of 1.8mm-2.2mm. By adjusting the process parameters such as laser power, scanning speed, and powder feed rate, the thickness and composition distribution of each layer are precisely controlled to ensure a strong interlayer bond.

[0018] In one embodiment of the present invention, in S2, the protective gas for the laser cladding technology is argon, and the gas flow rate is 9L / min-11L / min.

[0019] In one embodiment of the present invention, in step S2, the thickness of the CoCrNi alloy layer is 0.1mm-2mm, and the thickness of the CoCrNi-TiC composite layer is 0.1mm-3mm. The thickness of each layer of the CoCrNi alloy layer and the thickness of each layer of the CoCrNi-TiC composite layer are the same. This uniform thickness means that the distribution of CoCrNi and TiC is uniform throughout the cladding layer. This ensures that the distribution of hardness and wear resistance is relatively consistent across the entire surface.

[0020] In one embodiment of the present invention, in S2, the thickness of the CoCrNi-TiC composite layer is greater than the thickness of the CoCrNi alloy layer. The thinner CoCrNi alloy layer possesses better ductility and toughness, and can absorb some energy when subjected to external forces, preventing the material from undergoing brittle fracture due to over-hardening; while the thicker CoCrNi-TiC composite layer provides stronger hardness and wear resistance, thereby extending the service life of the material. Through this alternating thickness structural design, strong wear resistance can be achieved on the surface, while maintaining good crack resistance and toughness in the matrix. It can better disperse externally applied stress, avoid local stress concentration, and thus effectively improve fatigue resistance and impact resistance. It can maintain stability for a longer period of time under high loads, while avoiding the brittleness problem caused by excessively high hardness.

[0021] In one embodiment of the present invention, in S2, the thickness of different coatings is adjusted by modifying parameters such as laser power and scanning speed during the laser cladding process to form a structure with different layers, i.e., a heterogeneous structure. Based on this design, the thin-thickness heterogeneous structure allows the surface area of ​​the coating to have higher hardness to improve wear resistance, while the underlying layer has good toughness and crack resistance to enhance its impact resistance. By adjusting the thickness of the CoCrNi alloy layer and the CoCrNi-TiC composite layer, the hardness, toughness, and wear resistance of the CoCrNi-TiC composite coating can be effectively optimized. Using a heterogeneous structure not only reduces thermal stress between the coating and the substrate but also effectively improves the adhesion of the coating. Furthermore, by precisely controlling the bonding between the coating and the substrate, coating peeling or crack formation can be avoided, increasing the service life and reliability of the material.

[0022] In one embodiment of the present invention, in S2, the metal substrate is selected from H13 steel, H11 steel, H21 steel plate, H22 steel, H233 steel or H45 steel.

[0023] The second objective of this invention is to provide a CoCrNi-TiC composite coating prepared by the preparation method described above.

[0024] The technical solution of the present invention has the following advantages compared with the prior art:

[0025] (1) The preparation method described in this invention improves the hardness and wear resistance of the CoCrNi alloy matrix by adding TiC particles; through the alternating design of the CoCrNi alloy layer and the CoCrNi-TiC composite layer, the bonding force between the CoCrNi-TiC composite layer and the CoCrNi alloy layer is achieved, reducing delamination or crack propagation caused by thermal expansion differences and external stress, thereby improving the hardness, wear resistance, toughness and stability of the CoCrNi-TiC composite coating under high temperature and high stress environments. By adjusting the TiC content and the thickness of the alternating layers, the performance of the CoCrNi-TiC composite coating in practical applications can be improved.

[0026] (2) The preparation method described in this invention achieves uniform and stable distribution of TiC particles in the CoCrNi-TiC composite layer by precisely controlling the process parameters of laser cladding technology, the amount of TiC particles added, and the particle size of CoCrNi alloy powder and TiC particles, which significantly improves the hardness, wear resistance, stability and reliability of the CoCrNi-TiC composite coating.

[0027] (3) The CoCrNi-TiC composite coating of the present invention adopts an alternating structure design of CoCrNi alloy layer and CoCrNi-TiC composite layer. The CoCrNi-TiC composite layer provides higher hardness and wear resistance, while the CoCrNi alloy layer provides good toughness and impact resistance. The two work together to improve the wear resistance, heat resistance and fatigue resistance of the CoCrNi-TiC composite coating. In addition, the alternating layered structure design of CoCrNi alloy layer and CoCrNi-TiC composite layer can effectively disperse thermal stress and mechanical stress, thereby reducing the propagation of hot cracks and fatigue cracks. Furthermore, different layers of material can provide different thermal expansion adaptability when heated, enhancing the thermal shock resistance of the material and improving its fatigue resistance under repeated loads. The thickness and number of layers of CoCrNi alloy layer and CoCrNi-TiC composite layer can be adjusted according to actual application requirements, especially in high temperature, high pressure, wear and corrosion environments, such as important mechanical components such as aero-engines, automotive engine parts, and turbine blades. Attached Figure Description

[0028] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein:

[0029] Figure 1 SEM images of CoCrNi alloy powder (a), TiC particles (b), and composite powder (c) in Example 1 of this invention;

[0030] Figure 2This is a schematic diagram of the CoCrNi-TiC composite coating of Embodiment 2 of the present invention;

[0031] Figure 3 The microhardness test results are for the CoCrNi-TiC composite coating prepared in Example 1 of this invention.

[0032] Figure 4 The microhardness test results are for the CoCrNi-TiC composite coating prepared in the comparative example of Test Example 1 of this invention. Detailed Implementation

[0033] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. It should be understood that the specific embodiments are only used to explain the present invention, but the embodiments are not intended to limit the present invention.

[0034] In this invention, unless otherwise stated, the technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0035] In this invention, unless otherwise stated, the term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0036] In this invention, unless otherwise specified, the experimental methods used in the embodiments of this invention are conventional methods, and the materials and reagents used are commercially available unless otherwise specified.

[0037] In this invention, unless otherwise stated, the equipment used for laser cladding in the embodiments of this invention includes: a laser cladding system comprising a high-power laser, a powder feeding system, a control system, and a motion platform. The laser generates a high-intensity laser beam, which is focused onto the substrate surface through a focusing lens to form a high-temperature localized molten pool. The powder feeding system feeds CoCrNi alloy powder and composite powder into the molten pool through nozzles, respectively. The powder melts under the heat of the laser and bonds with the substrate surface. As the laser scan proceeds, the molten pool continuously expands, gradually cools, and solidifies, forming a uniform cladding layer. To achieve an alternating structure of CoCrNi-TiC composite layers and CoCrNi alloy layers of different thicknesses, the thickness, composition, and structure of the cladding layer are precisely controlled during the laser cladding process by adjusting parameters such as the scanning speed and powder feeding rate. By adjusting the powder distribution and the cooling rate of the molten pool, CoCrNi alloy powder and composite powder can alternately form a multi-layered structure. In addition, due to the high energy density of laser cladding, the temperature of the molten pool is very high, and TiC particles are rapidly melted and uniformly distributed in the CoCrNi alloy matrix.

[0038] In this invention, unless otherwise stated, the mass ratio of Co, Cr and Ni in the CoCrNi alloy powder used in the embodiments of this invention is 35:33:32.

[0039] In this invention, unless otherwise stated, the TiC particles used in the embodiments of this invention have a purity of 99%.

[0040] Example 1

[0041] The CoCrNi-TiC composite coating and its preparation method of the present invention specifically include the following steps:

[0042] S1. Substrate preparation: H13 steel plate is used as the substrate. In order to enhance the interfacial bonding strength between the cladding layer and the substrate surface, the substrate surface is polished with 600-grit sandpaper to ensure that the substrate surface has a certain roughness. After polishing, the polished substrate surface is cleaned with anhydrous ethanol to ensure that the substrate surface is free of oxide layer and impurities, so as to avoid the coating peeling off due to poor interfacial bonding after cladding. The polished surface is dried with a hair dryer to ensure that the substrate surface is dry.

[0043] S2. Preparation of composite powder: CoCrNi alloy powder with a particle size of 50μm-150μm was mixed with TiC particles with a particle size of 28μm-50μm, and then thoroughly ball-milled using a planetary ball mill at a ball-to-particle ratio of 2:1 for 4 hours to obtain a composite powder with a TiC mass fraction of 5%. Figure 1 );

[0044] S3. Using laser cladding technology, CoCrNi alloy powder and composite powder are alternately used to form a CoCrNi alloy layer with a thickness of 0.2 mm and a CoCrNi-TiC composite layer with a thickness of 0.4 mm on a metal substrate to obtain a CoCrNi-TiC composite coating; wherein, the CoCrNi alloy layer is directly prepared on the substrate surface, and both the CoCrNi alloy layer and the CoCrNi-TiC composite layer have 5 layers.

[0045] The process parameters for the CoCrNi alloy layer are as follows: laser power is 2400±10W, scanning speed is 10mm / s, powder feed rate is 2.5r / min, laser beam diameter is 2mm; the protective gas is argon, and the gas flow rate is 10L / min.

[0046] The process parameters for the CoCrNi-TiC composite layer are as follows: laser power is 2400±10W, scanning speed is 10mm / s, powder feed rate is 4.0r / min, laser beam diameter is 2mm; the protective gas is argon, and the gas flow rate is 10L / min.

[0047] Example 2

[0048] Basically the same as Example 1, except that the TiC content is replaced by 10% instead of 5%. Figure 2 The laser power is 2500±10W.

[0049] Example 3

[0050] The method is basically the same as in Example 1, except that the TiC content is replaced by 20% instead of 5%, and the laser power is 2700±10W.

[0051] Comparative Example 1

[0052] The process is basically the same as in Example 1, except that the TiC content is replaced by 30% instead of 5%, and the laser power is 2900±10W.

[0053] Comparative Example 2

[0054] The method is basically the same as in Example 1, except that the TiC content is replaced by 40% instead of 5%, and the laser power is 3100±10W.

[0055] Comparative Example 3

[0056] The basic structure is the same as in Example 1, except that the TiC content is replaced by 0 instead of 5%.

[0057] Test Example 1

[0058] Hardness tests were conducted on the CoCrNi-TiC composite coatings of Examples 1-3 and Comparative Examples 1-2. The surfaces of the CoCrNi-TiC composite coatings were smoothed using diamond sandpaper to ensure flatness and the absence of significant defects. The samples were placed on a Vickers hardness tester, and the hardness of each layer was tested using a Vickers hardness tester (load 100g) for 10 seconds. The hardness of each layer was measured individually. To ensure the feasibility of the experimental data, 12 points were taken for each layer, and the average hardness was taken as the final hardness data for that layer. A hardness curve was then plotted with the layer number as the x-axis and hardness as the y-axis. The results are shown below. Figures 3-4 As shown. From Figures 3-4 It can be seen that when the TiC content in the CoCrNi-TiC composite layer increases, the microhardness of the CoCrNi-TiC composite layer significantly improves, which is directly related to the high hardness and wear resistance of TiC ceramic particles. Through the alternating design of the CoCrNi alloy layer and the CoCrNi-TiC composite layer, a periodic distribution of hardness can be formed in the CoCrNi-TiC composite coating structure. This not only effectively improves the wear resistance of the material surface but also reduces thermal stress concentration within the coating and between the coating and the substrate, preventing the generation and propagation of cracks.

[0059] Test Example 2

[0060] Wear resistance tests were conducted on the CoCrNi-TiC composite coatings of Examples 1-3 and Comparative Examples 1-3 using a ball-and-disc wear test. The load was set at 30 N, the rotation speed at 200 rpm, and the time at 0.5 h. The specific test results are shown in Table 1.

[0061] Table 1

[0062] Sample Average coefficient of friction <![CDATA[Wear rate mm 3 / (N*m)]]> Example 1 0.545 <![CDATA[1.92×10 -4 ]]> Example 2 0.5804 <![CDATA[1.8×10 -4 ]]> Example 3 0.5596 <![CDATA[7.5×10 -5 ]]> Comparative Example 1 0.23 <![CDATA[3.24×10 -5 ]]> Comparative Example 2 0.2137 <![CDATA[1.73×10 -6 ]]> Comparative Example 3 0.5090 <![CDATA[2.05×10 -4 ]]>

[0063] As shown in Table 1, the average friction coefficient first increases and then decreases with increasing TiC content. Specifically, in the low content range (0%-10%), the friction coefficient increases to some extent, but when the TiC content is further increased (20% and above), the friction coefficient decreases and tends to a lower level. The wear rate, however, decreases significantly with increasing TiC content, indicating that the wear resistance of the CoCrNi-TiC composite coating continuously improves.

[0064] The trend of friction coefficient variation was analyzed: the average friction coefficient of pure CoCrNi alloy (without TiC) was approximately 0.5090. With the addition of a small amount of TiC reinforcing particles (5%), the friction coefficient increased slightly (to approximately 0.545). As the TiC content continued to increase to 10%, the friction coefficient reached its peak. In the experimental data, the composite material containing approximately 10% TiC had the highest average friction coefficient, reaching 0.5804. However, when the TiC content was further increased (above 20%), the friction coefficient began to decrease. When the TiC content reached 40%, the friction coefficient dropped to approximately 0.2137, even significantly lower than the friction coefficient without TiC. This non-monotonic change of "increasing first and then decreasing" indicates that the TiC reinforcing particle content has a complex effect on tribological behavior: moderate content increases frictional resistance, while high content decreases it.

[0065] Analysis of the wear rate trend: Unlike the friction coefficient, the wear rate shows a monotonically decreasing trend with increasing TiC content. The pure CoCrNi alloy exhibits the highest volumetric wear rate, approximately 2.05 × 10⁻⁶. -4 This indicates that the base alloy has relatively low wear resistance. The addition of TiC significantly reduces the wear rate: for example, with 5% TiC, the wear rate drops to approximately 1.92 × 10⁻⁶. -4 The wear rate is approximately 1.8 × 10⁻⁶ when TiC is present at 10%. -4 Subsequently, as the TiC content increased from 20% to 40%, the wear rate decreased slightly further, tending to around 10. -6 Orders of magnitude. Ultimately, the wear rate of the 40% TiC composite material was reduced by orders of magnitude compared to the unreinforced alloy, resulting in a significant improvement in wear resistance. This indicates that ceramic particles can significantly improve the wear resistance of the CoCrNi-TiC composite coating. Furthermore, as the TiC content further increased from 30% to 40%, the decrease in wear rate became smaller, suggesting that the improvement in wear resistance tends to saturate once the reinforcing particles form a more continuous reinforcing phase.

[0066] The formation of the TiC particle-reinforced network and its impact on friction: With increasing TiC content, a reinforcing "network" composed of the hard TiC phase gradually forms within the CoCrNi-TiC composite coating. At low content, TiC particles are sparsely distributed in the matrix, with large distances between them, offering limited support and reinforcement. At this stage, the material is still mainly supported by the soft CoCrNi matrix, which is prone to significant plastic deformation and adhesion during frictional contact, leading to a certain degree of adhesive wear and surface material transfer. The coefficient of friction is relatively low (because the soft matrix is ​​easily worn smooth during friction, forming a smooth contact). When the TiC content increases to a moderate level, the interparticle spacing shortens, and some TiC particles begin to connect or aggregate in the matrix, providing significant second-phase reinforcement. The hardness and strength of the CoCrNi matrix increase with increasing TiC content (indicating that the hard ceramic phase significantly improves load-bearing capacity and resistance to deformation). However, at this stage, TiC has not yet formed a completely continuous network, the interface area between the matrix and particles increases, and local stress concentration may occur at the interface. If TiC particles are unevenly distributed or poorly bonded to the matrix, these particles may loosen or detach during friction, causing abrasive particles to become trapped at the friction interface and increasing frictional resistance. In the "semi-strengthened" state, the material surface may exhibit uneven hardness and softness: the hard TiC protrudes to bear part of the load, while the surrounding softer matrix is ​​constrained and deformed. This easily causes fluctuations in microscopic contact during friction, and the coefficient of friction actually increases at this stage. When the TiC content is further increased to a high level (e.g., 30%-40%), TiC particles form a more continuous skeleton or network structure in the material. The matrix metal is divided and surrounded by the hard phase, and the composite material exhibits a "two-phase" (FCC matrix + TiC ceramic) structure. This continuous TiC network greatly enhances the overall hardness and rigidity of the material, making it difficult for the surface to produce large plastic deformation or ploughing under frictional loads. The hard network can hinder abrasive penetration and reduce the actual contact area, thus significantly reducing the contribution of the plastic plowing component to frictional resistance. At the same time, the presence of the TiC phase reduces the direct contact area between the metal matrix and weakens the effect of adhesive wear. Therefore, at high TiC content, the material exhibits a low and stable coefficient of friction and excellent wear resistance. The reinforcing network formed by 40% TiC content is expected to maintain the coefficient of friction at a low level (approximately 0.21), with wear occurring at a very low rate. However, if the TiC content is too high, it can lead to particle aggregation or increased interface defects, increasing the brittleness of the CoCrNi-TiC composite coating. At high TiC contents, the particles are very close together, making it easy for clusters and microcracks to form during sintering or solidification. Therefore, while 40% TiC provides a strong reinforcing network and wear resistance for the CoCrNi-TiC composite coating, it is necessary to ensure uniform distribution and a good interface during the process to avoid localized spalling due to embrittlement, which would adversely affect the friction performance.

[0067] In summary, the reinforcing network formed by TiC particles significantly improves the material's load-bearing capacity and hardness, reduces the wear rate, and lowers the coefficient of friction at high content by reducing contact with the soft matrix and plastic plowing. During this process, the material's friction mechanism gradually shifts from being dominated by adhesion / plastic deformation at low content to being dominated by slight abrasive wear dominated by the hard phase at high content, thus exhibiting a trend of initial deterioration followed by improvement in tribological properties.

[0068] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a CoCrNi-TiC composite coating, characterized in that, Includes the following steps: S1. CoCrNi alloy powder and TiC particles are mixed to obtain composite powder; the mass percentage of TiC particles in the composite powder is 5%-25%; the particle size of the CoCrNi alloy powder is 50μm-150μm; the particle size of the TiC particles is 28μm-50μm. S2. Using laser cladding technology, CoCrNi alloy powder and composite powder are alternately used to form CoCrNi alloy layers and CoCrNi-TiC composite layers on a metal substrate to obtain the CoCrNi-TiC composite coating. The CoCrNi alloy layer is directly formed on the surface of the metal substrate. Both the CoCrNi alloy layer and the CoCrNi-TiC composite layer have 4-6 layers. The thickness of the CoCrNi alloy layer is 0.1mm-2mm, and the thickness of the CoCrNi-TiC composite layer is 0.1mm-3mm. The thickness of the CoCrNi-TiC composite layer is greater than the thickness of the CoCrNi alloy layer. The process parameters of the laser cladding technology are: laser power of 2300W-3000W, scanning speed of 6mm / s-10mm / s, powder feed rate of 2.5r / min-4.0r / min, and laser beam diameter of 1.8mm-2.2mm.

2. The method for preparing the CoCrNi-TiC composite coating according to claim 1, characterized in that, In S1, the mass ratio of Co, Cr and Ni in the CoCrNi alloy powder is (34-36):(32-34):(31-33).

3. The method for preparing the CoCrNi-TiC composite coating according to claim 1, characterized in that, In S2, the protective gas for the laser cladding technology is argon, and the gas flow rate is 9L / min-11L / min.

4. The method for preparing the CoCrNi-TiC composite coating according to claim 1, characterized in that, In S2, the metal substrate is selected from H13 steel, H11 steel, H21 steel plate, H22 steel, H233 steel or H45 steel.

5. The CoCrNi-TiC composite coating prepared by the preparation method according to any one of claims 1-4.

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