Laser cladding wear-resistant bionic structure coating and preparation method thereof

Abstract

The invention provides a laser cladding wear-resistant bionic structure coating and a preparation method, the laser cladding wear-resistant bionic structure coating comprises a first layer, a second layer, a third layer, a fourth layer, a fifth layer and a sixth layer which are sequentially connected together from bottom to top, the first layer is made of soft materials, the second layer and the third layer are made of hard materials, the fourth layer and the fifth layer are made of composite materials, and the sixth layer is made of composite materials. The composite material comprises a soft material and a hard material, in the horizontal direction, the hard material and the soft material in the composite material are sequentially arranged in a crossed mode, and the sixth layer is a wear-resistant material; the first layer, the second layer and the third layer form a periodic area and are used for buffering and absorbing energy, the fourth layer and the fifth layer form an impact area and are used for enhancing the toughness of the coating, and the sixth layer is an impact surface and is used for improving wear resistance and bearing impact; by means of the design, the periodic area, the impact area and the impact surface are matched with one another, a complete protection system is formed, the characteristics of different materials are fully played, and balance between the rigidity and the toughness of the coating is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of new materials, and in particular, to a laser cladding wear-resistant bionic structure coating and a preparation method thereof. Background Art

[0002] Mechanical components operate in different working environments and will gradually fail, which has a great impact on the normal operation of machinery. In severe cases, it may cause casualties and significant economic losses. The failure of mechanical components is mainly manifested in the failure of the surface of the components. Surface failure is divided into wear failure, contact fatigue failure, and corrosion damage failure. With the continuous development of technology, the requirements for the surface performance of mechanical components in the mechanical industry have also gradually increased. Therefore, it is urgent to improve the surface performance of mechanical parts. Alloy steel is a commonly used metal material for manufacturing mechanical components. It has good plasticity, toughness, and wear resistance, and the cost is relatively low. It is often used for important components of large machinery. In the shipbuilding industry, a relatively large proportion of key components are made of alloy steel materials. The components are applied in working environments with high impact and easy wear, which poses a great challenge to the surface quality of the components. At present, a relatively effective technology with good application prospects for improving the performance and service life of alloy steel components is to prepare a high-impact wear-resistant coating on the surface of mechanical components.

[0003] Due to the characteristics of high uniformity of the formed structure, the ability to use various elements to form different alloy powders, and high automation degree, laser cladding technology has been widely studied in improving the surface performance of coatings. On this basis, various optimized processes have evolved, such as laser melting technology, laser remelting technology, ultra-high speed laser cladding technology, etc. The research ideas of scholars mainly focus on adjusting the proportion of constituent elements, in-situ generation or addition of particle reinforcement phases and particle sizes, and changing the preparation environmental conditions, etc., so that the hardness and wear resistance of the coating are greatly improved, but the toughness is significantly decreased. In many studies, the decrease in the toughness of the coating has not been analyzed in depth. The hardness and wear resistance of the coating correspond to the stiffness of the coating. The above research ideas cannot achieve the balance of stiffness and toughness at the same time.

[0004] The diverse material structure forms and interface characteristics in nature contain complex strong toughness mechanisms, bringing new research ideas for coatings to achieve high strength and toughness performance. By extracting various elements of special biological structures with excellent strength and toughness, applying a variety of materials, establishing and designing a bionic structure model with a strong toughness match, and finally using laser cladding technology to prepare the coating. Therefore, the present invention will introduce a high-impact wear-resistant biological (mantis shrimp foreclaw) structure as the core design, design the coating from the dimensions of structure, size and shape, and composition, and use laser cladding technology to prepare a bionic structure coating with high strength, high impact performance, and high wear resistance.

[0005] Patent CN114603142B discloses a preparation method of a grain-oriented bionic tool based on the microscopic structure of the mantis shrimp's club, which mainly imitates the "helical-laminated" microscopic structure of the mantis shrimp's club and is applied to cemented carbide tools to obtain a bionic tool with high strength and impact resistance. However, it does not solve the technical problem of simultaneously achieving the balance between the stiffness and toughness of the coating. Summary of the Invention

[0006] In view of this, the present invention aims to propose a laser cladding wear-resistant bionic structure coating and a preparation method to solve the problem that the balance between the stiffness and toughness of the coating cannot be achieved simultaneously in the prior art.

[0007] To achieve the above object, the technical solution of the present invention is realized as follows:

[0008] A laser cladding wear-resistant bionic structure coating includes a first layer, a second layer, a third layer, a fourth layer, a fifth layer, and a sixth layer connected together in sequence from bottom to top. Among them, the first layer is a soft material, the second and third layers are hard materials, the fourth and fifth layers are composite materials, and the composite materials contain soft materials and hard materials. In the horizontal direction, the hard materials and soft materials in the composite materials are arranged alternately, and the sixth layer is a wear-resistant material;

[0009] The first layer, the second layer, and the third layer form a periodic region for buffering and energy absorption, the fourth layer and the fifth layer form an impact region for enhancing the toughness of the coating, and the sixth layer is an impact surface for improving wear resistance and withstanding impact.

[0010] Further, the thickness of the first layer is 0.2 mm, and the thicknesses of the second layer, the third layer, the fourth layer, the fifth layer, and the sixth layer are all 0.6 mm.

[0011] Further, the impact surface is composed of a 725-1 graphite self-lubricating thin layer added with 2.0 wt.% nickel-coated graphite powder.

[0012] The present application provides a preparation method of a bionic structure coating for the aforementioned laser cladding wear-resistant bionic structure coating, including the steps:

[0013] S1: Put nickel-coated graphite powder and 725-1 powder into a planetary ball mill for mixing. The ball milling speed is 250 r / min, and the ball milling time is 8 h to obtain self-lubricating powder. Among them, the mass fraction of nickel-coated graphite powder is 2.0%, the particle size is 30-90 μm, the mass fraction of 725-1 powder is 98.0%, the particle size is 50-150 μm. Dry the self-lubricating powder, 725-1 powder, and IN625 alloy powder respectively. The drying temperature is 100°C - 120°C, and the drying time is 2 h. Then put the aforementioned three kinds of powder into three powder feeding barrels respectively;

[0014] S2: Grind the 38CrMoAl substrate to remove rust and oxides on the surface, then clean and dry it with acetone. Preheat the 38CrMoAl substrate to 250 °C and ensure that the temperature during the test is not lower than 200 °C;

[0015] S3: Use powder-fed laser cladding technology to clad the 725-1 powder and IN625 alloy powder on the surface of the 38CrMoAl substrate. Clad the IN625 soft material in the first layer, and clad the 725-1 hard material in the second and third layers in sequence. The first, second, and third layers form the periodic region of the bionic structure coating;

[0016] S4: Use powder-fed laser cladding technology to clad the fourth and fifth layers on the surface of the periodic region in sequence. In the fourth layer, clad the IN625 soft material first and then the 725-1 hard material, with the ratio of soft material to hard material being 1:10. The cladding methods of the fourth and fifth layers are the same. The fourth and fifth layers form the impact region of the bionic structure coating;

[0017] S5: Use powder-fed laser cladding technology to clad the sixth layer on the surface of the impact region. The sixth layer is the impact surface of the bionic structure coating;

[0018] S6: Quench and heat-treat the 38CrMoAl substrate clad with the bionic structure coating.

[0019] Furthermore, in step S3, the process parameters of laser cladding are as follows: the laser power is 1200 W, the scanning speed of the 725-1 powder is 12 mm / s, the scanning speed of the IN625 alloy powder is 16 mm / s, the powder feeding rate of the 725-1 powder is 1.0 r / min, the powder feeding rate of the IN625 alloy powder is 0.3 r / min, the spot diameter is 3 mm, and the argon gas flow rate is 20 L / min.

[0020] Furthermore, in step S4, the process parameters of laser cladding are as follows: the laser power is 1200 W, the scanning speed of the 725-1 powder is 12 mm / s, the scanning speed of the IN625 alloy powder is 16 mm / s, the powder feeding rate of the 725-1 powder is 1.0 r / min, the powder feeding rate of the IN625 alloy powder is 1.5 r / min, the spot diameter is 3 mm, and the argon gas flow rate is 20 L / min.

[0021] Furthermore, in step S5, the process parameters of laser cladding are as follows: the laser power is 1200 W, the scanning speed is 12 mm / s, the powder feeding rate is 1.0 r / min, the spot diameter is 3 mm, and the argon gas flow rate is 20 L / min.

[0022] Furthermore, in step S1, the self-lubricating powder, 725-1 powder and IN625 alloy powder are placed in a vacuum drying oven for drying.

[0023] Furthermore, in step S6, after the bionic structure coating is prepared, the 38CrMoAl substrate coated with the bionic structure coating is immediately placed in a heat treatment furnace for quenching heat treatment.

[0024] Compared with the prior art, the laser cladding wear-resistant bionic structure coating and preparation method described in the present invention have the following advantages:

[0025] The periodic area is composed of a soft first layer and a hard second and third layer. The soft first layer can absorb energy by its own good plasticity to increase the impact resistance of the coating. At the same time, the microhardness along the cross-section direction from the soft first layer to the hard second and third layers changes gradually, which enhances the toughness of the periodic area. The fourth and fifth layers in the impact area are composite materials with cross-arranged soft and hard materials. The soft material can absorb impact energy, and the hard material provides strength support. The synergistic effect of soft and hard materials further enhances the toughness of the coating, making the coating less likely to break when subjected to impact. The sixth layer is made of wear-resistant material, which can effectively resist wear and improve The high wear resistance of the coating, when subjected to impact, relies on its own strength to cope with impact damage, and cooperates with the hard material in the impact area to resist external impact force, so that the coating can still maintain good performance in high impact and easy wear environment, extending the service life of the coating; this design enables the periodic area, impact area and impact surface to cooperate with each other, from buffering energy absorption, enhancing toughness to improving wear resistance and impact resistance, forming a complete protection system; this bionic structural design gives full play to the characteristics of different materials and achieves a balance between coating stiffness and toughness. Compared with single material coatings, it can better meet the stringent requirements on material surface performance in actual engineering. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of the structure of the bionic structure coating according to an embodiment of the present invention;

[0027] Figure 2 The cross-sectional macroscopic morphology of the bionic structure coating according to the embodiment of the present invention;

[0028] Figure 3 (a) is a schematic diagram of the cross-sectional hardness point positions of the bionic structure coating, (b) is the microhardness distribution result of the surface layer of the impact area of ​​the bionic structure coating, and (c) is the microhardness distribution result along the thickness direction of the position in (a);

[0029] Figure 4 The test results of the surface wear resistance of the pure hard coating, substrate, and bionic structure coating described in the embodiments of the present invention;

[0030] Figure 5 Results of the impact test of the bionic structure coating, 725-1 pure hard coating, and substrate described in the embodiments of the present invention.

[0031] Description of the reference numerals:

[0032] 11. First layer; 12. Second layer; 13. Third layer; 14. Fourth layer; 15. Fifth layer; 16. Sixth layer. Detailed implementation manners

[0033] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the described embodiments are some but not all of the embodiments of the present invention. The specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0034] It should be noted that all the terms indicating directions and positions in the present invention, such as "upper", "lower", "left", "right", "front", "rear", "vertical", "horizontal", "inner", "outer", "top", "bottom", "tail end", "head end", "center", etc., are only used to explain the relative positional relationship and connection situation between components in a specific state, and are only for the convenience of describing the present invention, rather than requiring the present invention to be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention. In addition, the descriptions involving "first", "second", etc. in the present invention are only for descriptive purposes and cannot be construed as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. In addition, the meaning of "and / or" appearing throughout the text includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or a solution where A and B are satisfied simultaneously.

[0035] In the present invention, unless otherwise clearly defined and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and can be the internal communication of two components or the interaction relationship between two components, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0036] Embodiment 1

[0037] As Figure 1As shown, this embodiment provides a laser cladding wear-resistant bionic structure coating, including a first layer 11, a second layer 12, a third layer 13, a fourth layer 14, a fifth layer 15 and a sixth layer 16 connected together from bottom to top, wherein the first layer 11 is a soft material, the second layer 12 and the third layer 13 are hard materials, the fourth layer 14 and the fifth layer 15 are composite materials, the composite materials include soft materials and hard materials, in the horizontal direction, the hard materials and soft materials in the composite materials are arranged crosswise in sequence, and the sixth layer 16 is a wear-resistant material;

[0038] The first layer 11, the second layer 12 and the third layer 13 form a periodic region for buffering and absorbing energy, the fourth layer 14 and the fifth layer 15 form an impact region for enhancing the toughness of the coating, and the sixth layer 16 is an impact surface for improving wear resistance and bearing impact.

[0039] In the present application, the periodic region is composed of a soft first layer 11 and a hard second layer 12 and a third layer 13. The soft first layer 11 can absorb energy by its own good plastic buffering, thereby increasing the impact resistance of the coating. At the same time, the microhardness along the cross-sectional direction from the soft first layer 11 to the hard second layer 12 and the third layer 13 changes gradually, thereby enhancing the toughness of the periodic region. The fourth layer 14 and the fifth layer 15 of the impact region are composite materials of cross-arranged soft and hard materials. The soft material can absorb impact energy, and the hard material provides strength support. The synergistic effect of the soft and hard materials further enhances the toughness of the coating, thereby making the coating less likely to break when subjected to impact.

[0040] The sixth layer 16 serves as an impact surface and is made of wear-resistant material. It is in direct contact with the outside world and can effectively resist wear and improve the wear resistance of the coating. When subjected to impact, the impact surface relies on its own strength to cope with impact damage and cooperates with the hard material in the impact area to resist external impact force. This allows the coating to maintain good performance in a high-impact and wear-prone environment, thereby extending the service life of the coating.

[0041] This design enables the periodic area, impact area and impact surface to cooperate with each other, forming a complete protection system from buffering energy absorption, enhancing toughness to improving wear resistance and impact resistance; this bionic structural design gives full play to the characteristics of different materials and achieves a balance between coating stiffness and toughness. Compared with single material coatings, it can better meet the stringent requirements on material surface performance in actual engineering.

[0042] As a preferred example of the present application, the thickness of the first layer 11 is 0.2 mm, and the thickness of the second layer 12, the third layer 13, the fourth layer 14, the fifth layer 15 and the sixth layer 16 are all 0.6 mm.

[0043] Specifically, the first layer 11 has a thickness of 0.2 mm and serves as a soft material layer. This thickness can not only ensure that it has sufficient plasticity to buffer and absorb energy, effectively absorb external impact energy, and protect the overall structure of the coating, but also will not affect the overall strength of the coating due to excessive thickness. The second layer 12 and the third layer 13 both have a thickness of 0.6 mm and are made of hard materials. When combined with the relatively thin soft material of the first layer 11, it can make the microhardness in the cross-sectional direction from the substrate to the hard layer change in a gradient, increase the toughness of the periodic region, and at the same time provide a certain strength support.

[0044] The fourth layer 14 and the fifth layer 15 both have a thickness of 0.6 mm and serve as composite material layers in the impact area. Such a thickness ensures that when the soft material and the hard material are arranged crosswise in the horizontal direction, each can play its full role. The sufficient thickness allows the soft material to have space to absorb impact energy, and the hard material can also provide corresponding strength to resist impact deformation and damage, enhancing the toughness and impact resistance of the coating in the impact area.

[0045] The sixth layer 16 serves as the impact surface. A thickness of 0.6 mm ensures that the wear-resistant material can effectively play the role of improving wear resistance and withstanding impacts, so that it is not easily worn or damaged quickly under long-term friction and impacts, can maintain the performance of the coating for a long time, extend the service life of the coating, and ensure the stable operation of the coating in a high-impact and easy-to-wear working environment.

[0046] As a preferred example of the present application, the impact surface is composed of a 725-1 graphite self-lubricating thin layer added with 2.0 wt.% nickel-coated graphite powder.

[0047] Specifically, the 725-1 graphite self-lubricating thin layer is the main component of the impact surface. The 725-1 high-speed steel alloy has relatively high hardness and strength, which can provide basic wear resistance and impact resistance for the impact surface. On this basis, the formed self-lubricating thin layer itself has a certain anti-friction and lubrication effect, which can reduce the surface friction coefficient and reduce wear.

[0048] Adding 2.0 wt.% nickel-coated graphite powder to the 725-1 graphite self-lubricating thin layer is to further optimize the performance of the impact surface. Graphite has a unique layered crystal structure, and the bonding force between layers is weak and prone to slip. After adding nickel-coated graphite powder, during the friction process, these graphite particles can form a more continuous and effective lubricating film on the surface of the coating, further reducing the friction coefficient and improving the self-lubricating performance of the impact surface, thereby enhancing its wear resistance.

[0049] Preferably, the 725-1 graphite self-lubricating thin layer is based on the 725-1 high-speed steel alloy, and the added graphite particles are evenly distributed inside. During the preparation process, through laser cladding technology, the self-lubricating powder is melted and solidified to form the 725-1 graphite self-lubricating thin layer.

[0050] This application provides a preparation method for a bionic structure coating, which is used for the laser cladding wear-resistant bionic structure coating described above, and includes the steps:

[0051] S1: Put nickel-coated graphite powder and 725-1 powder into a planetary ball mill for mixing. The ball milling speed is 250 r / min, and the ball milling time is 8 h to obtain self-lubricating powder. Among them, the mass fraction of nickel-coated graphite powder is 2.0%, and the particle size is 30 - 90 μm. The mass fraction of 725-1 powder is 98.0%, and the particle size is 50 - 150 μm. Dry the self-lubricating powder, 725-1 powder, and IN625 alloy powder respectively. The drying temperature is 100°C - 120°C, and the drying time is 2 h. Then put the above three kinds of powder into three powder feeding barrels respectively;

[0052] S2: Grind the 38CrMoAl substrate to remove rust and oxides on the surface, then clean it with acetone and dry it. Preheat the 38CrMoAl substrate to 250°C and ensure that the temperature is not lower than 200°C during the test process;

[0053] S3: Use the powder feeding type laser cladding technology to clad 725-1 powder and IN625 alloy powder on the surface of the 38CrMoAl substrate. Clad the IN625 soft material in the first layer 11, and clad the 725-1 hard material in the second layer 12 and the third layer 13 in sequence. The first layer 11, the second layer 12, and the third layer 13 form the periodic region of the bionic structure coating;

[0054] S4: Use the powder feeding type laser cladding technology to clad the fourth layer 14 and the fifth layer 15 on the surface of the periodic region in sequence. In the fourth layer 14, first clad the IN625 soft material, and then clad the 725-1 hard material. The ratio of soft material to hard material is 1:10. The cladding methods of the fourth layer 14 and the fifth layer 15 are the same. The fourth layer 14 and the fifth layer 15 form the impact region of the bionic structure coating;

[0055] S5: Use the powder feeding type laser cladding technology to clad the sixth layer 16 on the surface of the impact region with the self-lubricating powder. The sixth layer 16 is the impact surface of the bionic structure coating;

[0056] S6: Quench and heat-treat the 38CrMoAl substrate clad with the bionic structure coating.

[0057] Specifically, in the periodic region of the bionic structure coating, the soft IN625 material can buffer and absorb energy, and the hard 725-1 material provides strength support. The combination of hard and soft materials makes the microhardness of the periodic region change in a gradient, increasing the toughness and impact resistance of the coating.

[0058] In the impact area, both soft materials absorb impact energy and hard materials resist deformation and damage, further enhancing the toughness and impact resistance of the coating in the impact area.

[0059] On the impact surface, graphite in the self-lubricating powder provides good self-lubricating performance, which can effectively reduce the friction coefficient, improve the wear resistance of the coating, and also withstand external impacts.

[0060] Using the powder-fed laser cladding technology, the powder delivery amount and cladding position can be precisely controlled, ensuring the thickness uniformity and composition stability of the coating. During the laser cladding process, the high-energy laser beam rapidly melts and solidifies the powder and the substrate surface, forming a metallurgical bond and improving the bonding strength between the coating and the substrate.

[0061] Quenching and heat treatment of the 38CrMoAl substrate with the clad bionic structure coating can further improve the microstructures of the coating and the substrate, increase the hardness, strength and wear resistance of the coating, eliminate the residual stress generated during the cladding process, and enhance the stability and reliability of the coating.

[0062] Specifically, in step S1, the 725-1 powder is a high-speed steel alloy powder, and the IN625 alloy powder is an Inconel625 alloy powder.

[0063] Table 1 - Elemental composition (wt.%) of 725-1 powder and IN625 alloy powder

[0064] Element Fe Cr Mo Co Nb Mn W V C Ni 725-1 Bal. 3.0-5.0 8.0-12.0 7.0-10.0 - ≤1.0 0.5-2.5 0.5-2.5 0.5-2.5 ≤1.0 IN625 0.75 20.0-23.0 8.0-10.0 ≤1.0 3.7 ≤5.0 - - ≤0.1 Bal.

[0065] Preferably, the chemical composition of the nickel-coated graphite powder is 75Ni25C, the particle size range is 30 - 90 μm, and the manufacturer is Beijing United Coating Technology Co., Ltd.

[0066] Preferably, in step S2, the surface of the 38CrMoAl substrate is polished using a grinding wheel.

[0067] As a preferred example of the present application, in step S3, the process parameters of laser cladding are: laser power is 1200W, the scanning speed for cladding 725-1 powder is 12mm / s, the scanning speed for cladding IN625 alloy powder is 16mm / s, the powder feeding rate of 725-1 powder is 1.0r / min, the powder feeding rate of IN625 alloy powder is 0.3r / min, the spot diameter is 3mm, and the argon gas flow rate is 20L / min.

[0068] Specifically, the 1200W laser power provides sufficient energy for powder melting, the lower scanning speed allows the 725-1 powder enough time to absorb energy and melt, and the higher scanning speed prevents the IN625 alloy powder from having coarse structure due to excessive energy, thus ensuring the quality and performance of the coating.

[0069] Such powder feeding rate setting, in combination with scanning speed, can ensure the appropriate powder supply per unit area. The stable powder feeding rate makes the coating composition uniform, avoids component segregation or uneven thickness, and ensures the consistency and stability of the coating in the periodic area.

[0070] The 3mm spot diameter ensures sufficient energy density for powder melting and bonding with the substrate, and can also control the size of the cladding area, which helps to improve the accuracy and quality of the coating.

[0071] Argon can effectively protect the molten pool during the cladding process, forming an inert gas protective layer on the surface of the molten pool, preventing the powder and the molten pool from being oxidized at high temperatures, reducing the generation of oxide inclusions, and improving the purity and performance of the coating.

[0072] As a preferred example of the present application, in step S4, the process parameters of laser cladding are: laser power is 1200W, the scanning speed of cladding 725-1 powder is 12mm / s, the scanning speed of cladding IN625 alloy powder is 16mm / s, the powder feeding rate of 725-1 powder is 1.0r / min, the powder feeding rate of IN625 alloy powder is 1.5r / min, the spot diameter is 3mm, and the argon gas flow rate is 20L / min.

[0073] Specifically, the scanning speed of cladding 725-1 powder is 12mm / s, and the scanning speed of IN625 alloy powder is 16mm / s. This setting not only avoids insufficient powder melting caused by too fast scanning speed, affecting the coating quality, but also prevents excessive energy input caused by too slow scanning speed, causing problems such as overheating of the coating structure and coarse grains.

[0074] This powder feeding rate setting can accurately control the ratio of soft IN625 alloy powder and hard 725-1 powder in the coating, ensuring that the design of soft material: hard material = 1:10 can be achieved, ensuring that the impact area has good toughness and impact resistance.

[0075] As a preferred example of the present application, in step S5, the process parameters of laser cladding are: laser power is 1200W, scanning speed is 12mm / s, powder feeding rate is 1.0r / min, spot diameter is 3mm, and argon flow rate is 20L / min.

[0076] Specifically, this setting can ensure a stable amount of powder deposited on the surface of the impact area per unit time, making the thickness of the coating on the impact surface uniform, ensuring the stability of its wear resistance and impact resistance. The stable powder deposition amount helps to form a uniform self-lubricating film, improve the self-lubricating performance of the impact surface, reduce the friction coefficient, and reduce wear.

[0077] As a preferred example of this application, in step S1, the self-lubricating powder, 725-1 powder, and IN625 alloy powder are respectively placed in a vacuum drying oven for drying.

[0078] Specifically, the powder usually contains a certain amount of moisture. In the high-temperature environment of laser cladding, the moisture will quickly vaporize to form steam. If not dried in advance, these steams will not have time to escape during the solidification process of the coating, and pores will be formed inside the coating. Drying the self-lubricating powder, 725-1 powder, and IN625 alloy powder separately can effectively remove moisture, avoid the generation of pores, ensure the denseness of the coating, and improve the strength and wear resistance of the coating; at the same time, the dried powder can better achieve metallurgical bonding with the surface of the substrate during laser cladding. The good bonding force can make the coating not easily fall off from the substrate when subjected to external forces such as impact and friction, improve the adhesion stability of the coating, and extend the service life of the coating.

[0079] As a preferred example of this application, in step S6, after the bionic structure coating is prepared, the 38CrMoAl substrate with the clad bionic structure coating is immediately placed in a heat treatment furnace for quenching heat treatment.

[0080] Specifically, the quenching treatment can change the organizational structure of the coating and the substrate, forming a denser and more uniform structure, thereby increasing the hardness of the coating. For the bionic structure coating, higher hardness means better wear resistance, enabling it to effectively resist external forces in actual applications when facing working conditions such as friction and wear, and extending the service life of the coating.

[0081] Comparative test:

[0082] The preparation method of the 725-1 coating includes the steps:

[0083] D1: Place the 725-1 powder in a vacuum drying oven for drying. The drying temperature is 100°C - 120°C, and the drying time is 2h, and then pour it into the powder feeding bucket;

[0084] D2: Use a grinding wheel to polish the 38CrMoAl substrate to remove the rust and oxides on the surface, then clean it with acetone and dry it. Preheat the 38CrMoAl substrate to 250°C and ensure that the temperature is not lower than 200°C during the test process;

[0085] D3: The 725-1 powder was cladded on the surface of the 38CrMoAl substrate by powder feeding laser cladding technology. The process parameters of laser cladding were as follows: laser power was 1200 W, scanning speed was 12 mm / s, powder feeding rate was 1.0 r / min, spot diameter was 3 mm, and argon gas flow rate was 20 L / min;

[0086] D4: After the coating was prepared, the 38CrMoAl substrate was immediately put into a heat treatment furnace for quenching heat treatment.

[0087] As Figure 2 shown, it is the macroscopic morphology of the cross-section of the bionic structure coating CD1 made of the coating imitating the front chela of mantis shrimp. It can be seen that the forming quality of the bionic structure coating CD1 prepared by the scheme of this application is good, and no defects such as cracks and pores appear. The structure is beautiful, and the actual structure conforms to the theoretical structure in combination with the characteristics of laser cladding technology.

[0088] As Figure 3 shown, for the bionic structure coating CD1 prepared by the scheme of this application, a hard-soft alternating hardness distribution is maintained on the surface layer of the impact area, which is the same as the hardness distribution law on the surface of the bionic inter-channel structure coating. Some hard units are affected by soft units, and the microhardness shows a gradient transition form from hard units to soft units; there are differences in the hardness distribution along the thickness direction of the cross-section at two positions in the impact area. The hardness distribution of Position1 (position 1) in the impact area is about 300 HV 0.5 or so, while the hardness distribution of Position2 (position 2) in the impact area is about 800 HV 0.5 or so. Because there is a 0.2-mm soft layer at the bottom of the coating, the hardness in the periodic area increases in a gradient form from about 300 HV 0.5 at the bottom layer to about 800 HV 0.5 of the hard units in the periodic area.

[0089] As Figure 4 shown, it is the comparison chart of the wear resistance of the bionic structure coating CD1, the 725-1 pure hard coating, and the substrate. It can be seen that the wear rates of the 725-1 pure hard coating, the substrate, and the CD1 coating are 4.90×10 -3 (mm / N·m), 2.70×10 -1 (mm / N·m), and 3.70×10 -3 (mm / N·m) respectively. The wear rate of the CD1 coating is the lowest, indicating that the bionic structure coating CD1 has more excellent wear resistance.

[0090] As Figure 5As shown, the test results of the impact test of the bionic structure coating CD1, the 725-1 pure hard coating, and the substrate are presented. The total impact energy of the CD1 coating is 44 J, while the total impact energy of the 725-1 pure hard coating is only 20 J. It can be seen that the impact resistance of the CD1 coating is much greater than that of the 725-1 coating. The lateral expansion value can reflect the fracture toughness of the impact specimen. The test results from largest to smallest are as follows: CD1 coating specimen = substrate specimen > 725-1 pure hard coating specimen. It can be seen that the CD1 coating and the substrate have the highest fracture toughness.

[0091] Here, it should be noted that the substrate refers to the 38CrMoAl matrix.

[0092] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be subject to the scope defined by the claims.

Claims

1. A laser cladding wear-resistant bionic structure coating, characterized in that It includes a first layer (11), a second layer (12), a third layer (13), a fourth layer (14), a fifth layer (15) and a sixth layer (16) which are connected together in sequence from bottom to top. Among them, the first layer (11) is made of soft material, the second layer (12) and the third layer (13) are made of hard materials, the fourth layer (14) and the fifth layer (15) are composite materials which contain soft materials and hard materials, and in the horizontal direction, the hard materials and soft materials in the composite materials are arranged alternately. The sixth layer (16) is made of wear-resistant material; The first layer (11), the second layer (12) and the third layer (13) form a periodic region for buffering and energy absorption. The fourth layer (14) and the fifth layer (15) form an impact region for enhancing the toughness of the coating. The sixth layer (16) is an impact surface for improving wear resistance and withstanding impacts.

2. The laser cladding wear-resistant bionic structure coating according to claim 1, characterized in that The thickness of the first layer (11) is 0.2 mm, and the thicknesses of the second layer (12), the third layer (13), the fourth layer (14), the fifth layer (15) and the sixth layer (16) are all 0.6 mm.

3. The laser cladding wear-resistant bionic structure coating according to claim 1, characterized in that, The impact surface is composed of a 725-1 graphite self-lubricating thin layer added with 2.0 wt.% nickel-coated graphite powder.

4. A preparation method of a bionic structure coating, for the laser cladding wear-resistant bionic structure coating according to any one of claims 1-3, characterized in that, It includes steps: S1: Put nickel-coated graphite powder and 725-1 powder into a planetary ball mill for mixing. The ball milling speed is 250 r / min, and the ball milling time is 8 h to obtain self-lubricating powder. Among them, the mass fraction of nickel-coated graphite powder is 2.0%, the particle size is 30-90 μm, the mass fraction of 725-1 powder is 98.0%, the particle size is 50-150 μm. Dry the self-lubricating powder, 725-1 powder and IN625 alloy powder respectively. The drying temperature is 100℃ - 120℃, and the drying time is 2 h. Then put the above three kinds of powders into three powder feeding barrels respectively; S2: Grind the 38CrMoAl substrate to remove rust and oxides on the surface, then clean it with acetone and dry it. Preheat the 38CrMoAl substrate to 250℃ and ensure that the temperature is not lower than 200℃ during the test process; S3: Use the powder feeding type laser cladding technology to clad 725-1 powder and IN625 alloy powder on the surface of the 38CrMoAl substrate. Clad IN625 soft material on the first layer (11), and clad 725-1 hard materials on the second layer (12) and the third layer (13) in sequence. The first layer (11), the second layer (12) and the third layer (13) form the periodic region of the bionic structure coating; S4: Use the powder feeding type laser cladding technology to clad the fourth layer (14) and the fifth layer (15) on the surface of the periodic region in sequence. First clad IN625 soft material on the fourth layer (14), and then clad 725-1 hard material. The ratio of soft material to hard material is 1:

10. The cladding methods of the fourth layer (14) and the fifth layer (15) are the same. The fourth layer (14) and the fifth layer (15) form the impact region of the bionic structure coating; S5: Using powder feeding laser cladding technology, apply the self-lubricating powder to clad the sixth layer (16) on the surface of the impact area. The sixth layer (16) is the impact surface of the bionic structure coating. S6: Quench and heat-treat the 38CrMoAl substrate clad with the bionic structure coating.

5. The preparation method of the bionic structure coating according to claim 4, wherein, In step S3, the process parameters of laser cladding are as follows: the laser power is 1200 W, the scanning speed for cladding 725-1 powder is 12 mm / s, the scanning speed for cladding IN625 alloy powder is 16 mm / s, the powder feeding rate of 725-1 powder is 1.0 r / min, the powder feeding rate of IN625 alloy powder is 0.3 r / min, the spot diameter is 3 mm, and the argon gas flow rate is 20 L / min.

6. The preparation method of the bionic structure coating according to claim 4, characterized in that In step S4, the process parameters of laser cladding are as follows: the laser power is 1200 W, the scanning speed for cladding 725-1 powder is 12 mm / s, the scanning speed for cladding IN625 alloy powder is 16 mm / s, the powder feeding rate of 725-1 powder is 1.0 r / min, the powder feeding rate of IN625 alloy powder is 1.5 r / min, the spot diameter is 3 mm, and the argon gas flow rate is 20 L / min.

7. The preparation method of the bionic structure coating according to claim 4, wherein In step S5, the process parameters of laser cladding are as follows: the laser power is 1200 W, the scanning speed is 12 mm / s, the powder feeding rate is 1.0 r / min, the spot diameter is 3 mm, and the argon gas flow rate is 20 L / min.

8. The preparation method of the bionic structure coating according to claim 4, characterized in that, In step S1, put the self-lubricating powder, 725-1 powder, and IN625 alloy powder into a vacuum drying oven for drying respectively.

9. The preparation method of the bionic structure coating according to claim 4, characterized in that, In step S6, after the bionic structure coating is prepared, immediately put the 38CrMoAl substrate clad with the bionic structure coating into a heat treatment furnace for quench and heat treatment.

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