CoCrNi-TiC gradient cladding layer and preparation method thereof

Abstract

The invention relates to a CoCrNi-TiC gradient cladding layer and a preparation method thereof, and belongs to the technical field of coatings. The preparation method comprises the following steps that S1, TiC particles and CoCrNi alloy powder with different contents are mixed, and CoCrNi-based cladding powder with different TiC contents is obtained; s2, the CoCrNi-based cladding powder with the different TiC contents is prepared into CoCrNi-based gradient coatings with the different TiC contents on a metal substrate through the laser cladding technology, and the CoCrNi-TiC gradient cladding layer is obtained through stress annealing; and the TiC contents in the CoCrNi-based gradient coatings with different TiC contents are linearly increased. The high-quality gradient cladding layer not only has good adhesive force, but also can bear large mechanical stress, and is suitable for the application field needing to bear high load and high impact.

Description

Technical Field

[0001] The present invention belongs to the technical field of coatings, and particularly relates to a CoCrNi-TiC gradient cladding layer and a preparation method thereof. Background Art

[0002] As an advanced surface modification technology, laser cladding has been widely used in die repair, aerospace component strengthening, and high-performance mechanical part manufacturing. By depositing high-performance materials on the substrate surface through laser cladding technology, the wear resistance, corrosion resistance, and high-temperature performance of the die surface can be significantly improved. However, the cladding layers deposited by traditional laser cladding usually have problems such as insufficient interfacial bonding strength and uneven property transition, which are prone to cause stress concentration, resulting in cracks or peeling on the die surface and affecting the service life of the die.

[0003] Single-layer cladding is the earliest laser cladding technology, which forms a strengthened single-layer coating on the substrate surface by depositing a single material. Its advantages are simple process and suitability for surface strengthening of conventional components. Due to the physical property differences (such as thermal expansion coefficient, hardness, etc.) between the substrate and the cladding layer material, cracks or peeling are likely to occur in the single-layer coating during service, and the interfacial bonding performance is poor.

[0004] Reinforced-phase ceramic particle composite cladding technology has become a key research direction in recent years by adding ceramic particles (such as TiC, WC) to the cladding layer to improve hardness and wear resistance. The increase in reinforcing particles can significantly improve the hardness and wear resistance of the coating; however, the reinforcing-phase particles are prone to agglomeration or uneven distribution during the cladding process, resulting in unstable properties such as local hardness and strength of the coating. In addition, due to the large difference in thermal expansion coefficient between the ceramic and the metal substrate, residual stress is easily formed at the interface, affecting the overall performance.

[0005] To solve the above problems, gradient coating design technology has gradually emerged. By gradually changing the material composition layer by layer, the properties of the coating gradually change from the substrate to the surface, which can relieve the stress concentration problem at the interface. Although the gradient design improves the interfacial bonding performance to a certain extent and enhances the service reliability of the coating as a whole. However, the existing gradient designs are mostly simple segmented linear designs, and the interlayer composition and property transition are relatively rough, making it difficult to meet the requirements of multi-property collaborative optimization under complex working conditions. In addition, the control of process parameters such as laser power and powder feeding rate is not yet perfect, resulting in poor stability of the gradient coating.

[0006] Therefore, developing a gradient cladding layer structure with uniform property transition has important engineering application value. Summary of the Invention

[0007] To solve the above technical problems, the present invention provides a CoCrNi-TiC gradient cladding layer and a preparation method thereof. Through a uniform gradient design with a gradually increasing mass fraction of TiC particles, a continuous transition of the composition and properties of the gradient cladding layer is achieved. The interfacial bonding force of the material is optimized, and the occurrence of interfacial peeling and cracks is significantly reduced. By the composite distribution of small-sized TiC particles and large-sized CoCrNi alloy powders, the hardness and wear resistance of the gradient cladding layer are further improved, ensuring the synergistic consistency of the properties at the micro and macro levels. Through the dynamic optimization of the process parameters of laser cladding, the real-time matching of laser energy and material deposition rate is achieved, ensuring the stability and uniformity of the molten pool, and further improving the consistency of the quality of the gradient cladding layer and the repeatability of the process.

[0008] The first object of the present invention is to provide a preparation method of a CoCrNi-TiC gradient cladding layer, comprising the following steps:

[0009] S1. Mix TiC particles and CoCrNi alloy powders with different contents respectively to obtain CoCrNi-based cladding powders with different TiC contents;

[0010] S2. By laser cladding technology, make CoCrNi-based gradient coatings with different TiC contents on a metal substrate, and obtain the CoCrNi-TiC gradient cladding layer through stress annealing; the TiC content in the CoCrNi-based gradient coatings with different TiC contents increases linearly, ensuring a smooth transition of the properties of the CoCrNi-TiC gradient cladding layer.

[0011] In an embodiment of the present invention, in S1, the elemental composition and mass percentage of the CoCrNi alloy powder are: Co 34.2%-34.3%, Cr 29.7%-29.8%, Ni 35.5%-35.6%, Cu 0.0004%-0.0006%, Mn 0.001%-0.002%, Ti 0.009%-0.01%, S 0.0025%-0.003%, P 0.005%-0.0055%, and the balance is other inevitable impurities.

[0012] In an embodiment of the present invention, in S1, the particle size of the TiC particles is 3 μm - 10 μm; the particle size of the CoCrNi alloy powder is 15 μm - 53 μm.

[0013] In one embodiment of the present invention, in S1, the TiC particles (titanium carbide) are a common hard ceramic material with high hardness, wear resistance, and high temperature resistance. The introduction of TiC particles can greatly improve the hardness and wear resistance of the gradient cladding layer, especially having significant advantages in high-temperature and low-friction environments. The combination of TiC particles and CoCrNi medium-entropy alloy can produce the following effects through the process of co-deposition or melting: First, hardness improvement: As a hard phase, TiC makes the material surface obtain higher hardness after its addition, greatly enhancing the wear resistance of the material. In a friction environment, TiC particles can effectively reduce the wear of the material surface, thereby extending the service life of the material. Second, high temperature resistance: TiC particles have excellent stability at high temperatures and will not undergo structural changes or degradation. Therefore, the addition of TiC particles improves the high-temperature stability of the gradient cladding layer and can maintain the mechanical properties of the material in a high-temperature environment for a long time. Third, composite strengthening of the material: The synergistic effect between TiC particles and CoCrNi medium-entropy alloy makes the overall material have a balance in terms of strength, toughness, hardness, etc. By reasonably adjusting the mass fraction of TiC particles, the performance of the material under different working conditions can be controlled. For example, a higher TiC content helps to improve hardness and wear resistance, while a lower TiC content can better maintain toughness.

[0014] In one embodiment of the present invention, in S1, the CoCrNi alloy powder, as a medium-entropy alloy (MEA), has a disordered distribution of multiple elements (such as Co, Cr, Ni) in the solid solution. Its structural characteristics and unique alloying method give it significant advantages in harsh environments such as high temperature, high pressure, and corrosion: First, high-entropy effect: The fusion of multiple elements such as Co, Cr, Ni can increase the mixing entropy of the alloy, which makes the alloy have higher phase stability, can effectively inhibit grain growth, and enhances the oxidation and corrosion resistance of the material at high temperatures. Second, high-temperature tolerance: The CoCrNi alloy has high stability in a high-temperature environment, can withstand a relatively high working temperature without undergoing a phase change or a significant decline in mechanical properties, and thus has good reliability in high-temperature applications. Third, excellent mechanical properties: The solid solution strengthening effect of the entropy alloy makes the alloy have a relatively high yield strength and ductility. At the same time, the ratio of Co and Cr in the CoCrNi alloy makes the material have better corrosion resistance and wear resistance, especially performing excellently in harsh working environments. During the laser cladding process, due to the high-temperature effect of the molten pool, the elements of the CoCrNi medium-entropy alloy can be uniformly dissolved and distributed on the substrate surface, thereby forming an alloy layer with excellent high-temperature mechanical properties, corrosion resistance, and high-entropy characteristics.

[0015] In one embodiment of the present invention, in S1, the TiC content in the CoCrNi-based cladding powder with different TiC contents is 0%-25%.

[0016] In one embodiment of the present invention, in S2, the process parameters of the laser cladding technology are as follows: the laser power is 1600W - 2000W, the scanning speed is 12mm / s - 15mm / s, and the powder feeding rate is 4.8r / min - 5.2r / min. By precisely controlling parameters such as the laser power, scanning speed, and powder feeding rate, the stability of the molten pool can be ensured and the substrate surface can be evenly covered to control the quality and hardness of the gradient coating, providing strong support for the preparation of the CoCrNi / TiC gradient cladding layer.

[0017] In one embodiment of the present invention, in S2, the laser cladding technology is based on the principle of high-energy focused heating of a laser beam. Using a laser as a heat source, materials such as metal powders and ceramic particles are melted and reacted with the substrate surface. By precisely controlling process parameters such as the laser power, scanning speed, and powder feeding rate, precise cladding of local areas can be achieved, enabling different functions and properties to be obtained on the surface of the material. Compared with traditional means such as casting and powder metallurgy, the laser cladding technology has the following advantages: First, precise local heating and material selective deposition: The laser cladding technology has a high degree of precision, can perform local heating and melting treatment on the material surface, adapt to workpieces with complex geometries, and avoid the problems of difficult temperature control and material waste commonly found in traditional casting or heat treatment methods. Second, high-efficiency material utilization: The powder or wire form used in laser cladding can precisely control the feeding amount according to needs, reduce material waste, and achieve high-efficiency material utilization. Third, enhanced design freedom of properties: Through the laser cladding technology, a uniform or gradient structure can be formed in the material according to requirements, enabling materials with different properties (such as hardness, toughness, high-temperature resistance, etc.) in different regions, making the design of functional gradient materials more flexible and precise.

[0018] In one embodiment of the present invention, in S2, the number of layers of the CoCrNi-based gradient coating with different TiC contents is 4 - 8 layers, and the single-layer thickness is 1.0mm - 1.4mm.

[0019] In one embodiment of the present invention, in S2, the linearly increasing gradient is 1% - 5%.

[0020] In one embodiment of the present invention, in S2, the rate of stress annealing is 0.9℃ / s - 1.1℃ / s; at this rate, not only can the residual stress generated during the cladding process due to factors such as local temperature changes and uneven cooling of the molten pool be eliminated, but also the thermal stress, cracks, or other defects caused by sudden temperature changes can be avoided, thereby ensuring the structural stability and performance uniformity of the coating.

[0021] 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; which is used to provide high strength and toughness.

[0022] In one embodiment of the present invention, in S2, through the precise control of the laser cladding technology, a functional gradient structure with different physical and chemical properties can be formed on the material surface. These gradient structures can optimize the properties of the material gradually from the surface to the inner layer according to the requirements of different working conditions: First, the strengthening of the surface layer: The surface layer can improve hardness and wear resistance by adjusting the mass fraction of TiC particles, and is suitable for working in high friction and high impact environments. Second, the design of the transition layer: Due to the temperature and cooling rate gradients during the laser cladding process, the microstructure formed on the material surface can be layered, so that the properties of different regions have good transitions, avoiding problems such as brittle fracture existing in traditional materials. Third, the toughness and impact resistance of the inner layer: The inner layer of the material is mainly composed of CoCrNi medium entropy alloy, which has good toughness and impact resistance. Through the layer-by-layer deposition during the cladding process, the inner layer material maintains good ductility and crack resistance, and is suitable for bearing large mechanical loads.

[0023] The second object of the present invention is to provide a CoCrNi-TiC gradient cladding layer prepared by the described preparation method.

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

[0025] (1) The preparation method of the present invention realizes the precise design of functional gradient materials by combining the laser cladding technology with different mass fractions of CoCrNi medium entropy alloy and TiC particles. Utilizing the high-energy focusing effect of the laser, the distribution of alloy elements and particles is controlled in different gradient cladding layers, thereby achieving ideal performance optimization. In addition, the laser cladding technology melts the powder with a high-energy density laser beam and deposits it on the surface of the substrate to form a firm bonding layer. This high-quality gradient cladding layer not only has good adhesion, but also can withstand large mechanical stresses, and is suitable for application fields that need to bear high loads and high impacts.

[0026] (2) The preparation method of the present invention realizes a gradient structure with different TiC contents on the surface of the same workpiece through the laser cladding process. The distribution of TiC particles varies with the depth of the gradient cladding layer, thereby providing multi-level performance optimization for the component, ensuring both the hardness of the surface layer and the toughness and strength of the substrate, and being suitable for high-performance components that require a gradient structure.

[0027] (3) During the laser cladding process of the preparation method of the present invention, the reinforcing phase TiC particles interact with the molten CoCrNi alloy matrix and are uniformly distributed in the gradient cladding layer, thus significantly improving the hardness and wear resistance of the gradient cladding layer. The hardness of TiC particles is much higher than that of the CoCrNi alloy matrix. As the reinforcing phase, they are dispersed in the CoCrNi alloy matrix, hindering the movement of dislocations, thereby enhancing the anti-deformation ability of the material. In addition, these reinforcing phase particles reduce the plastic deformation of the CoCrNi alloy matrix by filling the gaps in the CoCrNi alloy matrix and increasing the interface strength, enhancing the anti-wear property of the gradient cladding layer. Due to the chemical stability and high melting point of TiC particles, they also improve the high-temperature resistance and corrosion resistance of the gradient cladding layer. Especially in friction and high-temperature environments, the gradient cladding layer can better maintain the structural stability and performance. Therefore, the presence of the second-phase particles not only improves the hardness and wear resistance of the gradient cladding layer but also enhances its anti-damage ability under extreme working conditions.

[0028] (4) The TiC particles in the CoCrNi-TiC gradient cladding layer of the present invention have extremely high hardness and wear resistance and are uniformly distributed in the gradient cladding layer, which can effectively improve the surface properties of the substrate and are particularly suitable for components in high-wear environments. In addition, the CoCrNi alloy itself has good corrosion resistance, and the addition of TiC particles can further enhance its ability to resist chemical corrosion. Especially in some harsh working environments, such as high-temperature, high-humidity, acidic or alkaline environments, the corrosion resistance of the composite material can be significantly improved, thereby extending the service life of the component. Therefore, the combination of the high-temperature stability and corrosion resistance of the CoCrNi alloy and the hardness improvement and wear resistance of TiC particles endows the material with excellent comprehensive properties. Description of the Drawings

[0029] In order to make the content of the present invention easier to be clearly understood, the following further details the present invention according to specific embodiments of the present invention in combination with the drawings, where:

[0030] Figure 1 SEM image of TiC particles in Example 1 of the present invention;

[0031] Figure 2 SEM image of CoCrNi alloy powder in Example 1 of the present invention;

[0032] Figure 3 Schematic diagram of the CoCrNi-TiC gradient cladding layer in Example 1 of the present invention;

[0033] Figure 4 Schematic diagram of the sampling points in Test Example 1 of the present invention;

[0034] Figure 5Schematic diagram of the change in the microhardness of the CoCrNi-TiC gradient cladding layer in Example 1 of the present invention with the TiC content;

[0035] Figure 6 Schematic diagram of the change in the microhardness of the CoCrNi-TiC gradient cladding layer in Example 2 of the present invention with the TiC content;

[0036] Figure 7 Schematic diagram of the change in the microhardness of the CoCrNi-TiC gradient cladding layer in Comparative Example 1 of the present invention with the TiC content;

[0037] Figure 8 Crystal phase structure of the CoCrNi-TiC gradient cladding layer in Comparative Example 1 of the present invention. Detailed implementation manners

[0038] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, so that those skilled in the art can better understand the present invention and be able to implement it. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. It should be understood that the specific embodiments are only used to explain the present invention, but the exemplified embodiments are not used as a limitation to the present invention.

[0039] In the present invention, unless otherwise specified, the technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the technical field to which the present invention belongs.

[0040] In the present invention, unless otherwise specified, the term "and / or" includes any and all combinations of one or more of the related listed items.

[0041] In the present invention, unless otherwise specified, the experimental methods used in the embodiments of the present invention are all conventional methods without special instructions, and the materials, reagents, etc. used can be obtained from commercial channels without special instructions.

[0042] In the present invention, unless otherwise specified, the equipment used for laser cladding in the embodiments of the present invention includes: an IPG fiber laser equipped with a laser scanning system, a powder feeding system, and an atmosphere protection system.

[0043] In the present invention, unless otherwise specified, the elemental composition and its mass percentage of the CoCrNi alloy powder used in the embodiments of the present invention are: Co 34.27%, Cr 29.74%, Ni 35.56%, Cu 0.0005%, Mn 0.0016%, Ti 0.0098%, S 0.0026%, P 0.0052%, and the balance is other inevitable impurities.

[0044] Example 1

[0045] The CoCrNi-TiC gradient cladding layer of the present invention and its preparation method specifically include the following steps:

[0046] S1. Preparation of the substrate: Use an H13 steel plate as the substrate. To enhance the interfacial bonding strength between the cladding layer and the substrate surface, the substrate surface is polished with 600-mesh sandpaper to ensure a certain roughness on the substrate surface. After polishing, the polished substrate surface is cleaned with absolute ethanol to ensure that there is no oxide layer or impurity on the substrate surface, avoiding the peeling of the coating after cladding due to poor interfacial bonding.

[0047] S2. Preparation of the cladding powder: Use TiC particles with a particle size of 3μm - 10μm ( Figure 1 ) as the reinforcement phase. According to the preset TiC content (0%, 2%, 4%, 6%, 8%, 10%), mix the TiC particles with CoCrNi alloy powder with a particle size of 15μm - 53μm ( Figure 2 ), and then use a planetary ball mill for sufficient ball milling. The ball-to-powder ratio is 2:1, and the ball milling time is 4h to obtain CoCrNi-based cladding powder with different TiC contents.

[0048] S3. Preparation of CoCrNi-based gradient coatings with different TiC contents: Through laser cladding technology, using the method of layer-by-layer laser beam cladding, make CoCrNi-based cladding powder with different TiC contents into CoCrNi-based gradient coatings on the substrate, and the single-layer thickness is 1.2mm. Among them, the process parameters of the laser cladding technology are: the atmosphere is high-purity argon (≥99.9%), the gas flow rate is 10L / min, the defocus amount is 2.8mm, the laser power is 1600 - 2000W, the scanning speed is 12mm / s - 15mm / s, and the powder feeding rate is 4.8r / min - 5.2r / min. To ensure that the cladding powder can be evenly melted during the cladding process, when the TiC content is greater than 6%, appropriately increase the laser power and reduce the scanning speed to increase the energy density, ensuring that the cladding powder can fully absorb the laser energy and be melted.

[0049] S4. Preparation of the CoCrNi-TiC gradient cladding layer: Use an asbestos net to wrap the sample after cladding, and slowly stress anneal the gradient coating to room temperature at a rate of 1℃ / s to obtain the CoCrNi-TiC gradient cladding layer ( Figure 3 ).

[0050] Example 2

[0051] Basically the same as Example 1, the difference is that the gradient change of the TiC content is replaced from 0, 2%, 4%, 6%, 8%, 10% to 5%, 10%, 15%, 20%, 25%.

[0052] Comparative Example 1

[0053] Basically the same as Example 1, except that the gradient change of TiC content is replaced from 0, 2%, 4%, 6%, 8%, 10% to 10%, 20%, 30%, 40%, 50%.

[0054] Test Example 1

[0055] The CoCrNi-TiC gradient cladding layers of Examples 1-2 and Comparative Example 1 were subjected to hardness testing. The surface of the CoCrNi-TiC gradient cladding layer was polished with diamond sandpaper to ensure the flatness of the test surface and no significant defects. The samples were placed on a Vickers hardness tester for testing. The hardness of each layer was tested using a Vickers hardness tester (load 100 g), and the holding time was 10 s. Hardness tests were carried out at multiple positions of each sample, and 8 points were taken for each sample test ( Figure 4 ) to ensure the accuracy of the data. The hardness values of each sample were recorded, and the average hardness value was calculated. The results are as Figures 5 - 7 shown.

[0056] It can be seen from Figure 5 that as the TiC content increases, the hardness of the CoCrNi alloy gradually increases. When the TiC content is 10%, the hardness is the highest, reaching 346 HV, which is 63.5% higher than that of the alloy without TiC addition (220 HV). It shows that TiC particles have an obvious strengthening effect on the hardness of the CoCrNi alloy. The addition of TiC particles can effectively improve the hardness of the alloy. As the TiC content increases, TiC particles begin to be distributed in the CoCrNi alloy matrix, gradually enhancing the anti-friction performance and wear resistance of the alloy. The uniform distribution of TiC particles and their combination with the matrix play a key role in improving the hardness.

[0057] It can be seen from Figure 6 that as the TiC content increases, the hardness of the CoCrNi alloy gradually increases. When the TiC content increases from 5% to 25%, the hardness increases from 258 HV to 527 HV, and the overall increase amplitude is 104%, showing a significant strengthening effect of TiC on the hardness. When the TiC content is relatively low (5%), the increase amplitude of the hardness is relatively large. When the TiC content increases from 5% to 15%, the hardness increases from 258 HV to 425 HV, and the hardness increases by 64%, showing the initial strengthening effect of TiC particles on the alloy. As the TiC content further increases, the hardness continues to increase, and the increase amplitude is relatively significant.

[0058] It can be seen from Figure 7 that although the hardness still increases when the TiC content exceeds 40%, significant crack and pore problems appear in the gradient cladding layer ( Figure 8)。The quality of the gradient cladding layer deteriorates, showing a relatively obvious increase in brittleness and non-uniformity. This is because the addition of excessive TiC particles leads to incomplete bonding between the TiC particles and the CoCrNi alloy matrix in the cladding layer, resulting in stress concentration and crack generation in the gradient cladding layer. In addition, a high content of TiC particles may not be completely melted during the laser cladding process, leading to the generation of pores between the particles.

[0059] In summary, as a hardening reinforcement phase, TiC particles can significantly improve the hardness of the alloy. With the increase in the TiC content, the microstructure of the alloy changes significantly. The uniform distribution of TiC particles and the interaction between the particles gradually enhance the hardness of the alloy, strengthen the lattice strength of the alloy, inhibit the slip of dislocations, and thus improve the compressive strength and anti-friction performance of the alloy. When the TiC content is low (such as 5%-10%), the TiC particles are relatively uniformly distributed and can effectively fill the grain boundaries and defects of the alloy, so the strengthening effect is relatively significant; when the TiC content is high (such as 20%-25%), the interaction between TiC particles increases, which may lead to slightly over-dense bonding between the particles, thus affecting the toughness of the alloy. When the TiC content is even higher (exceeding 40%), the relative density of TiC particles increases, and the interaction between TiC particles and the insufficient melting during the heat treatment process will lead to poor bonding between TiC particles and non-uniformity of the gradient cladding layer, resulting in cracking and pore generation of the structure, and further affecting the overall mechanical properties of the alloy.

[0060] Obviously, the above embodiments are merely examples given for clear illustration and are not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A method for preparing a CoCrNi-TiC gradient cladding layer, characterized in that: The following steps are involved: S1, respectively mixing TiC particles with different contents and CoCrNi alloy powder to obtain CoCrNi-based cladding powders with different TiC contents; S2. CoCrNi-based gradient coatings with different TiC contents are prepared on a metal substrate using laser cladding technology from CoCrNi-based cladding powders with different TiC contents, and the CoCrNi-TiC gradient cladding layer is obtained by stress annealing; the TiC content in the CoCrNi-based gradient coatings with different TiC contents increases linearly.

2. The method for preparing the CoCrNi-TiC gradient cladding layer according to claim 1, characterized in that: In S1, the element composition and mass percentage of the CoCrNi alloy powder are: Co 34.2%-34.3%, Cr 29.7%-29.8%, Ni 35.5%-35.6%, Cu 0.0004%-0.0006%, Mn 0.001%-0.002%, Ti 0.009%-0.01%, S 0.0025%-0.003%, P 0.005%-0.0055%, and the balance is other inevitable impurities.

3. The method for preparing the CoCrNi-TiC gradient cladding layer according to claim 1, characterized in that: In S1, the particle size of the TiC particles is 3 μm-10 μm; the particle size of the CoCrNi alloy powder is 15 μm-53 μm.

4. The method for preparing the CoCrNi-TiC gradient cladding layer according to claim 1, characterized in that: In S1, the TiC content in the CoCrNi-based cladding powders with different TiC contents is 0%-25%.

5. The method for preparing the CoCrNi-TiC gradient cladding layer according to claim 1, characterized in that: In S2, the process parameters of the laser cladding technology are: laser power is 1600W-2000W, scanning speed is 12mm / s-15mm / s, and powder feeding rate is 4.8r / min-5.2r / min.

6. The method for preparing the CoCrNi-TiC gradient cladding layer according to claim 1, characterized in that: In S2, the number of layers of the CoCrNi-based gradient coatings with different TiC contents ranges from 4 to 8 layers, and the thickness of a single layer ranges from 1.0 mm to 1.4 mm.

7. The method for preparing the CoCrNi-TiC gradient cladding layer according to claim 1, characterized in that: In S2, the linear increasing gradient is 1%-5%.

8. The method for preparing a CoCrNi-TiC gradient cladding layer according to claim 1, characterized in that: In S2, the stress annealing rate is 0.9°C / s-1.1°C / s.

9. The method for preparing a CoCrNi-TiC gradient cladding layer 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.

10. A CoCrNi-TiC gradient cladding layer prepared by the preparation method according to any one of claims 1 to 9.

Images