A wear resistant workpiece having a diamond composite coating and a method of making the same

Abstract

This invention relates to the fields of laser surface engineering and superhard material coating technology, specifically to a wear-resistant workpiece with a diamond composite coating and its preparation method. The wear-resistant workpiece includes a substrate with multiple pits, at least some of which are embedded with first diamond particles. A first brazing filler metal is disposed on the substrate, partially filling the pits and coating the first diamond particles. A metal-based diamond composite coating is disposed on the first brazing filler metal, comprising a second brazing filler metal and second diamond particles. First, a pit array is etched on the substrate using a femtosecond laser to fill the pits with the first diamond particles. A metal binder is then coated inside the pits and on the substrate surface. Then, a cladding layer is formed by coaxial powder-feeding laser cladding, resulting in a two-layer composite wear-resistant structure with a substrate embedding layer and a surface cladding layer. This effectively increases the thickness of the wear-resistant layer, significantly improves the wear resistance of the workpiece, and extends its service life.

Description

Technical Field

[0001] This invention relates to the fields of laser surface engineering and superhard material coating technology, and more specifically, to a wear-resistant workpiece with a diamond composite coating and its preparation method. Background Technology

[0002] Diamond composite coatings are widely used in industrial wear-resistant applications. Existing preparation technologies mainly rely on brazing, chemical vapor deposition (CVD), and thermal spraying, but there are still obvious shortcomings: the brazing filler metal is prone to oxidation or softening under high-temperature conditions, leading to coating peeling; CVD diamond coatings have high deposition temperatures and limited coating thickness, making it difficult to meet the requirements of heavy-duty wear resistance; although thermal spraying can quickly prepare thick coatings, the high-temperature flame can easily cause diamond graphitization, and the coating bonding strength is low, making it difficult to achieve high-strength metallurgical bonding.

[0003] Although conventional laser cladding can achieve the preparation of thick coatings and realize the metallurgical bonding between the metal coating and the substrate, the following problems still exist: (1) The high temperature of the molten pool leads to severe graphitization of the diamond surface, which significantly reduces hardness and wear resistance; (2) The bonding between diamond and metal substrate mainly relies on mechanical anchoring, and the interfacial bonding force is insufficient, which makes it easy for particles to fall off and fail under cyclic load; (3) The large density difference between diamond and metal powder makes it easy for component segregation to occur during the cladding process, affecting the uniformity of the coating; (4) The high thermal stress during the preparation of thick coatings makes it easy to cause cracks; (5) The narrow process parameter window requires precise balance of energy density and cooling rate, otherwise diamond ablation or lack of fusion may occur.

[0004] To address these shortcomings, existing research primarily employs the following methods: introducing a transition layer to alleviate thermal stress and improve diamond graphitization, interfacial bonding, and post-weld cracking; however, the multilayer structure exacerbates stress concentration and increases costs; using low-temperature laser technology to reduce diamond graphitization sacrifices coating bonding strength and deposition efficiency; designing composite powder systems and adding reinforcing phases to improve performance, but limitations in diamond content, stress compatibility, and process costs prevent breakthroughs in high-content, thick-layer coatings; and using post-treatment strengthening methods such as hot isostatic pressing to enhance bonding strength and reduce internal defects, but these methods are costly and have limited effectiveness in addressing core issues such as diamond thermal damage and component segregation, making it difficult to fundamentally overcome existing technological bottlenecks.

[0005] In view of this, the present invention is hereby proposed. Summary of the Invention

[0006] The purpose of this invention is to provide a wear-resistant workpiece with a diamond composite coating and its preparation method. By pre-constructing a micro-nano array pit structure on the surface of the workpiece substrate, filling it with diamond particles, coating it with a metal binder, and then forming a double-layer composite structure with an embedded diamond bottom layer and a surface cladding layer by coaxial powder feeding laser cladding, the workpiece can reduce residual stress, optimize diamond distribution and interface bonding, suppress diamond thermal damage, and effectively improve the wear resistance of the workpiece.

[0007] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: A wear-resistant workpiece with a diamond composite coating includes a substrate, wherein the substrate has a plurality of pits, and at least a portion of the pits are embedded with first diamond particles. The substrate is provided with a first brazing filler metal, and the first brazing filler metal partially fills the pit and covers the first diamond particle. The first solder is provided with a metal-based diamond composite coating, which includes a second solder and a second diamond particle.

[0008] Preferably, the particle size of the first diamond particle and the second diamond particle are independently 40-800 mesh.

[0009] Preferably, the opening width of the pit is 1-2 times the particle size of the first diamond particle, wherein the opening width refers to the maximum width at the opening of the pit.

[0010] Preferably, the depth-to-width ratio of the recess is 0.5-1.5, where the depth-to-width ratio refers to the ratio of the depth of the recess to its opening width.

[0011] Preferably, the pit spacing is 1.3-2.5 times the pit opening width, wherein the pit spacing refers to the distance between the centers of two adjacent pits.

[0012] Preferably, the filling rate of the pit is ≥85%.

[0013] Preferably, the morphology of the pit includes at least one of cylindrical, hexagonal prism, and inverted conical shapes.

[0014] Preferably, the arrangement of the pits includes any one of the following: hexagonal close-packed array, rectangular array, circular array, and cross array.

[0015] Preferably, the first brazing filler metal includes any one of Ni-based alloys, Cu-based alloys, Co-based alloys, Fe-based alloys, Ag-based alloys, and high-entropy alloys.

[0016] Preferably, the thickness of the metal-based diamond composite coating is 0.3-1.2 mm.

[0017] Preferably, the second solder includes any one of Ni-based alloys, Cu-based alloys, Co-based alloys, Fe-based alloys, Ag-based alloys, and high-entropy alloys.

[0018] Preferably, the material of the substrate includes any one of 316L stainless steel, 45# steel, H13 mold steel, and cemented carbide.

[0019] The method for preparing a wear-resistant workpiece with a diamond composite coating as described in any of the foregoing embodiments includes the following steps: S1. Dents are etched on the substrate surface using a femtosecond laser; S2. Fill the pit with the first diamond particle, and coat the pit and the substrate with a metal binder; S3. The second brazing filler powder is mixed with the second diamond particles to obtain a composite powder, and a metal-diamond composite coating is prepared on the surface of the substrate coated with the metal binder by a coaxial powder feeding laser cladding method.

[0020] Preferably, the surface of the first diamond particle and / or the second diamond particle is provided with a coating, wherein the coating includes any one of Cr, Ti, Ni, and W.

[0021] Preferably, in step S2, the metal binder includes a first solder powder and a liquid medium, wherein the mass percentage of the first solder powder in the metal binder is 50%-90%.

[0022] Preferably, the first solder powder includes any one of Ni-based alloy powder, Cu-based alloy powder, Co-based alloy powder, Fe-based alloy powder, Ag-based alloy powder, and high-entropy alloy powder.

[0023] Preferably, the first solder powder contains Ti and / or Cr.

[0024] Preferably, the liquid medium includes at least one of ethanol, propylene glycol, water, and water glass.

[0025] Preferably, in step S3, the second solder powder includes any one of Ni-based alloy powder, Cu-based alloy powder, Co-based alloy powder, Fe-based alloy powder, Ag-based alloy powder, and high-entropy alloy powder.

[0026] Preferably, in step S3, the particle size of the second alloy powder is 45-105 μm.

[0027] Preferably, in step S3, the mass percentage of the second diamond particles in the composite powder is 5%-50%.

[0028] Preferably, in step S3, the powder feeding rate of the coaxial powder feeding laser cladding is 5-25 g / min, the laser power is 800-3500 W, the scanning speed is 3-15 mm / s, the spot diameter is 1-3 mm, and the overlap rate is 40%-60%.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows: The microstructure of the pit array on the workpiece substrate in this invention disperses the cladding thermal stress, and the gradient transition of the double-layer structure effectively alleviates CTE mismatch and reduces residual stress. Diamonds are pre-placed within the pits and temporarily fixed with a metal binder, forming a "mechanical-metallurgical" dual bond during cladding. The coaxial powder-feeding cladding layer further strengthens the interface and enhances the diamond bonding strength. The diamonds within the pits are exposed to molten pool heat for a short time and are isolated by the metal binder, reducing direct high-temperature exposure, inhibiting diamond thermal damage, and reducing the degree of diamond graphitization. Furthermore, the array distribution of the pre-placed diamonds avoids particle agglomeration, and the powder-feeding cladding layer replenishes the second phase, achieving diamond gradient control and effectively improving compositional uniformity. The double-layer composite coating structure of "surface cladding layer + substrate inlay layer" effectively increases the overall coating thickness and extends the wear-loss process. After the surface cladding layer wears out preferentially, the diamonds in the substrate inlay layer continue to provide a wear-resistant framework. Compared with traditional laser cladding coatings, the effective wear-resistant life of the coating is significantly improved. Attached Figure Description

[0030] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0031] Figure 1 This is a schematic diagram of the preparation process of the diamond composite coating of the present invention; Figure 2 The image shows the two-dimensional morphology (left) of the pit array in Embodiment 1 of the present invention and the three-dimensional morphology (right) of some of the pits. Figure 3 The images shown are: the left image (after filling the pit with diamond particles) and the right image (after spraying a portion of the metal binder) in Embodiment 1 of the present invention. Figure 4 These are topographic images of the surface and the adjacent substrate surface after laser cladding in Embodiment 1 of the present invention; Figure 5 This is a topographic image of the surface and the adjacent substrate surface after laser cladding in Comparative Example 1 of the present invention; Figure 6 This is a cross-sectional view of the laser cladding process in Embodiment 1 of the present invention; Figure 7 This is a cross-sectional view of laser cladding in Comparative Example 1 of the present invention; Figure 8 This is a cross-sectional microstructure diagram of the laser cladding section after laser cladding in Embodiment 1 of the present invention; Figure 9 This is a cross-sectional microstructure diagram of the laser cladding section in Comparative Example 1 of the present invention; Figure 10 This is a cross-sectional view of laser cladding in Comparative Example 2 of the present invention. Detailed Implementation

[0032] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0033] The first aspect of the present invention provides a wear-resistant workpiece with a diamond composite coating, comprising a substrate, wherein the substrate has a plurality of pits, and at least some of the pits are embedded with first diamond particles. A first brazing filler metal is provided on the substrate, and the first brazing filler metal partially fills the pit and covers the first diamond particle, so that the first diamond particle forms a metallurgical bond with the substrate. The first solder has a metal-based diamond composite coating, which includes a second solder and a second diamond particle.

[0034] The wear-resistant workpiece of the present invention has a first diamond particle embedded on the surface of the workpiece substrate, and the two form a metallurgical bond, realizing a dual bond of "mechanical interlocking and metallurgical bonding" between the first diamond particle and the substrate; at the same time, a metal-diamond composite coating is provided on the surface of the embedded layer to form a double-layer wear-resistant structure, which can effectively increase the thickness of the wear-resistant layer and significantly improve the wear resistance life of the workpiece.

[0035] In some specific embodiments of the present invention, the particle size of the first diamond particle and the second diamond particle are independently 40-800 mesh, for example, they can be any one value or a range of any two values ​​among 40 mesh, 60 mesh, 80 mesh, 100 mesh, 200 mesh, 400 mesh, 600 mesh, and 800 mesh; wherein, the particle size of the first diamond particle and the second diamond particle can be the same or different.

[0036] In some specific embodiments of the present invention, the first diamond particle and the second diamond particle are shaped as at least one of spherical, octahedral, or irregular shapes.

[0037] In some specific embodiments of the present invention, the opening width of the pit is 1-2 times the diameter of the first diamond particle. For example, it can be any one value or a range of any two values ​​among 1, 1.2, 1.5, 1.8, and 2 times the diameter. The purpose is to ensure that the first diamond particle can be at least partially embedded in the pit, and the exposed height of the first diamond particle is preferably ≤50% of the particle diameter. The opening width refers to the maximum width at the opening of the pit, that is, the distance between the two farthest points at the opening of the pit.

[0038] In some specific embodiments of the present invention, the depth-to-width ratio of the pit is 0.5-1.5. For example, it can be any one value or a range of any two values ​​among 0.5, 0.8, 1, 1.2, and 1.5. The depth-to-width ratio refers to the ratio of the depth of the pit to the width of its opening.

[0039] In some specific embodiments of the present invention, the pit spacing is 1.3-2.5 times the pit opening width. For example, it can be any one value or a range of any two values ​​among 1.3 times, 1.5 times, 1.8 times, 2 times, 2.2 times, and 2.5 times. Controlling the pit spacing and pre-placing diamond particles in the pits can prevent diamond aggregation during cladding. The pit spacing refers to the distance between the centers of two adjacent pits.

[0040] In some specific embodiments of the present invention, the filling rate of the pits is ≥85%, that is, not less than 85% of the pits are inlaid with the first diamond particle. For example, the pit filling rate can be any one value or a range of any two values ​​among 85%, 90%, 95%, and 100%. Too low a filling rate will affect the wear resistance of the workpiece.

[0041] In some specific embodiments of the present invention, the morphology of the pit includes at least one of cylindrical, hexagonal prism, and inverted conical shapes; in other embodiments, the morphology of the pit may also be other regular or irregular shapes.

[0042] In some specific embodiments of the present invention, the arrangement of the pits on the substrate includes any one of a hexagonal close-packed array, a rectangular array, a circular array, and a cross array; in other embodiments, other periodic arrangements may also be used.

[0043] In some specific embodiments of the present invention, the first brazing filler metal includes any one of Ni-based alloys, Cu-based alloys, Co-based alloys, Fe-based alloys, Ag-based alloys, and high-entropy alloys.

[0044] In some specific embodiments of the present invention, the thickness of the metal-based diamond composite coating is 0.3-1.2 mm, for example, it can be any one value or a range of any two values ​​among 0.3 mm, 0.5 mm, 0.8 mm, 1.0 mm, and 1.2 mm.

[0045] In some specific embodiments of the present invention, the second brazing filler metal includes any one of Ni-based alloys, Cu-based alloys, Co-based alloys, Fe-based alloys, Ag-based alloys, and high-entropy alloys.

[0046] In some specific embodiments of the present invention, the material of the workpiece substrate includes any one of 316L stainless steel, 45# steel, H13 mold steel, and cemented carbide.

[0047] like Figure 1 As shown, a second aspect of the present invention provides a method for preparing a wear-resistant workpiece with a diamond composite coating as described in any of the foregoing embodiments, comprising the following steps: S1. Dents are etched on the substrate surface using a femtosecond laser; S2. The first diamond particle is filled into the pit, and a metal adhesive is applied to the pit and the substrate; wherein, applying the metal adhesive to the pit means: when the first diamond particle is completely embedded in the pit, the metal adhesive is applied to the pit, covering the first diamond particle, and part of it penetrates through the gaps to the bottom of the pit, wrapping the first diamond particle; when the first diamond particle is partially embedded in the pit, the metal adhesive is applied to the surface of the first diamond particle, and part of it penetrates through the gaps to the bottom of the pit, wrapping the first diamond particle. S3. The second alloy powder is mixed with the second diamond particles to obtain a composite powder, and a metal-diamond composite coating is prepared on the surface of a substrate coated with a metal binder by a coaxial powder feeding laser cladding method.

[0048] The microstructure of the femtosecond laser-induced pits disperses the thermal stress of cladding. The dual-layer gradient transition of matrix embedding and surface cladding effectively alleviates CTE mismatch and reduces residual stress. The pits provide pre-positioning space for diamonds, reducing interference from subsequent cladding on particle distribution. By optimizing the mechanical interlocking of diamond particles through the pits, the mechanical interlocking effect is enhanced. After pre-positioning the first diamond particle, a metal binder is applied to temporarily fix the diamond particle, which serves as a transition layer during cladding, promoting the diamond / metal interface reaction, forming carbides, and improving the interfacial bonding strength, thus forming a dual bond of "mechanical interlocking and metallurgical bonding." Furthermore, the pits also protect the diamond particles. It reduces direct high-temperature exposure, inhibits diamond thermal damage, and reduces the degree of diamond graphitization. Furthermore, the first diamond particle in the pit is located at the bottom of the molten pool, and is exposed to the heat of the molten pool for a short time during cladding, which can inhibit diamond thermal damage and reduce the degree of diamond graphitization. The array distribution of pre-placed diamonds avoids particle agglomeration, and the powder feeding of the cladding layer supplements the second phase, which can realize the gradient control of diamond composition and effectively improve the composition uniformity. Coaxial powder feeding cladding forms a dense wear-resistant layer, which together with the diamond bottom layer embedded in the matrix constitutes a double-layer composite wear-resistant structure, which has both wear resistance and bonding strength, improves the overall thickness of the wear-resistant layer, and can significantly improve the service life of the workpiece.

[0049] In some specific embodiments of the present invention, the depth of the pit is ≤0.5mm. The purpose is to ensure the heat input at the bottom of the pit during coaxial powder feeding laser cladding, so that its temperature can meet the conditions for the metal binder to melt and interact with diamond, thus ensuring the formation of a metallurgical bond.

[0050] In some specific embodiments of the present invention, in step S1, before the femtosecond laser etches the pits, the substrate is mechanically polished and ultrasonically cleaned or sandblasted to remove the oxide layer on the substrate surface and ensure that the substrate surface is clean and free of oil.

[0051] In some specific embodiments of the present invention, in step S1, the wavelength of the femtosecond laser is 515-2580nm, for example, it can be any single value or a range of any two values ​​among 515nm, 780nm, 1030nm, 1053nm, and 2580nm; the pulse width is 100fs-1ps, for example, it can be any single value or a range of any two values ​​among 100fs, 300fs, 500fs, 800fs, and 1ps; the average laser power is 2.4-4.8W, for example, it can be any single value or a range of any two values ​​among 2.4W, 3W, 3.6W, 4.2W, and 4.8W; the spot diameter is 5-100μm, for example, it can be... The scanning method is either a single value or a range of any two values ​​from 5μm, 10μm, 20μm, 50μm, and 100μm; the scanning speed is 100-1200mm / s, for example, it can be any single value or a range of any two values ​​from 100mm / s, 150mm / s, 300mm / s, 500mm / s, 800mm / s, 1000mm / s, and 1200mm / s; the repetition frequency is 50kHz-10MHz, for example, it can be any single value or a range of any two values ​​from 50kHz, 100kHz, 500kHz, 1000kHz (1MHz), 5MHz, and 10MHz.

[0052] In some specific embodiments of the present invention, the surfaces of the first diamond particle and / or the second diamond particle are coated with a layer comprising any one of Cr, Ti, Ni, and W. By pre-plating a highly active metal layer onto the surface of the diamond particles, the surface is modified, improving the wettability between the diamond and the cladding metal, enhancing the interfacial bonding strength, and reducing the risk of diamond particle peeling. Simultaneously, the coating acts as a diffusion barrier, preventing elements such as Fe and Co from reacting with the diamond at high temperatures, increasing the graphitization initiation temperature of the diamond, and inhibiting high-temperature graphitization. This is more suitable for the extreme environmental requirements of long-life wear-resistant components, such as extreme high-temperature (>800℃), high-stress wear, or corrosive environments (e.g., deep well drilling bits, hot rolling mill coatings, and mining crusher cutters).

[0053] In some specific embodiments of the present invention, in step S2, the first diamond particle is filled into the pit by ultrasonic vibration or mechanical vibration, and the filling rate is preferably ≥85%.

[0054] In some specific embodiments of the present invention, in step S2, the metal adhesive is applied by micro-droplet spraying or screen printing.

[0055] In some specific embodiments of the present invention, in step S2, the metal binder includes a first solder powder and a liquid medium. The mass percentage of the first solder powder in the metal binder is 50%-90%, for example, it can be any one value or a range of any two values ​​among 50%, 60%, 75%, and 90%.

[0056] In some specific embodiments of the present invention, the first alloy powder includes any one of Ni-based alloy powder, Cu-based alloy powder, Co-based alloy powder, Fe-based alloy powder, Ag-based alloy powder, and high-entropy alloy powder.

[0057] In some specific embodiments of the present invention, the first solder powder contains Ti and / or Cr, that is, the first solder powder is a solder powder containing active elements, which can improve the bonding effect of diamond / metal. For example, the first solder powder contains the active element Ti, which can generate a TiC reinforcing phase.

[0058] In some specific embodiments of the present invention, the liquid medium used includes at least one of ethanol, propylene glycol, water, and water glass.

[0059] In some specific embodiments of the present invention, in step S3, the second solder powder includes any one of Ni-based alloy powder, Cu-based alloy powder, Co-based alloy powder, Fe-based alloy powder, Ag-based alloy powder, and high-entropy alloy powder.

[0060] In some specific embodiments of the present invention, in step S3, the particle size of the second alloy powder is 45-105 μm. For example, it can be any one value or a range of any two values ​​among 45 μm, 60 μm, 75 μm, 90 μm, and 105 μm.

[0061] In some specific embodiments of the present invention, in step S3, the mass percentage of the second diamond particle in the composite powder is 5%-50%, for example, it can be any one value or a range of any two values ​​from 5%, 10%, 20%, 30%, 40%, 50%.

[0062] In some specific embodiments of the present invention, in step S3, a ball mill is used to fully mix the second metal powder and diamond particles.

[0063] In some specific embodiments of the present invention, in step S3, the powder feeding rate of the coaxial powder-feeding laser cladding is 5-25 g / min, for example, it can be any one value or a range of any two values ​​among 5 g / min, 10 g / min, 15 g / min, 20 g / min, and 25 g / min; the laser power is 800-3500 W, for example, it can be any one value or a range of any two values ​​among 800 W, 1000 W, 1500 W, 2000 W, 2500 W, 3000 W, and 3500 W; scanning The speed is 3-15 mm / s, for example, it can be any single value or a range of any two values ​​from 3 mm / s, 5 mm / s, 8 mm / s, 10 mm / s, 12 mm / s, and 15 mm / s; the spot diameter is 1-3 mm, for example, it can be any single value or a range of any two values ​​from 1 mm, 1.5 mm, 2 mm, 2.5 mm, and 3 mm; the overlap rate is 40%-60%, for example, it can be any single value or a range of any two values ​​from 40%, 45%, 50%, 55%, and 60%.

[0064] In some specific embodiments of the present invention, the coaxial powder feeding laser cladding process uses high-purity Ar (99.99%) as the protective gas, and the protective gas flow rate is 10-25 L / min. For example, it can be any one value or a range of any two values ​​among 10 L / min, 15 L / min, 20 L / min, and 25 L / min.

[0065] The following detailed description of some embodiments of the present invention is provided in conjunction with specific examples. Unless otherwise specified, all raw materials used in the embodiments are commercially available.

[0066] Example 1 (1) Femtosecond laser etched pit array Martensitic stainless steel was used as the substrate, and pretreated with sandblasting, sandpaper polishing, and alcohol cleaning. Femtosecond laser etching of the pits was employed, using a wavelength of 1030 nm, a scanning speed of 150 mm / s, a repetition frequency of 10 MHz, a pulse width of 211 fs, an average power of 2.9 W, a spot diameter of 10 μm, and two repetitions. The resulting pits had a depth of approximately 105 μm, a maximum width of approximately 200 μm, and were hexagonal prisms with a spacing of approximately 330 μm between adjacent holes, forming a rectangular array (e.g., ...). Figure 2 (As shown).

[0067] (2) Pre-place the first diamond particle and coat it with a metal binder. Select 120-150 mesh first-grade diamond particles, use a mixture of near-spherical and octahedral shapes, and employ ultrasonic vibration to assist in filling the pits (e.g., ...). Figure 3As shown in the figure, the metal adhesive is then filled into the pits and substrate surface using micro-droplet spraying, repeated 3 times to form a coating of about 30 μm on the surface; wherein, the first solder powder and liquid medium are mixed to obtain the metal adhesive, the first solder powder is selected as BNi2 powder, and the liquid medium is composed of 60 wt% propylene glycol and 40 wt% water; the mass of BNi2 powder and liquid medium are mixed at 1:1, and then placed indoors to dry for 24 hours.

[0068] (3) Coaxial powder feeding laser cladding The second diamond particles are selected from 200-mesh broken material (irregular shape), and the second brazing filler powder is selected from BNi60 powder (45-105μm). The mass ratio of the second diamond particles to the second brazing filler powder is 1:9. The mixture is ball-milled for 6 hours to achieve mechanical mixing and obtain composite powder for laser cladding. Laser cladding parameters: wavelength 1080nm, laser power 2400W, scanning rate 10mm / s, spot diameter 3mm, overlap rate 40%, powder feeding rate 10 g / min, protective gas flow rate 15 L / min, argon protection.

[0069] Example 2 Example 2 is similar to Example 1, except that: In step (1), the femtosecond laser uses a wavelength of 1030nm, a scanning speed of 150mm / s, a repetition frequency of 1MHz, a pulse width of 211fs, a laser power of 4.83W (using 65%, i.e., an average power of 3.1395W), and is repeated 10 times; the resulting pit has a depth of 80μm, a maximum width of 120μm, is cylindrical, and has a spacing of 220μm between adjacent holes, forming a hexagonal close-packed array; In step (2), select 200-mesh first diamond particles, and fill them with a mixture of irregular shapes and octahedrons.

[0070] All other conditions are the same as in Example 1.

[0071] Example 3 Example 3 is similar to Example 1, except that: In step (2), the first brazing filler metal is Ticusil, an active brazing filler metal. The first diamond particles of 150-180 mesh are nearly spherical and easily generate TiC to achieve metallurgical bonding. In step (3), the laser power is selected as 2000W; All other conditions are the same as in Example 1.

[0072] Comparative Example 1 Comparative Example 1 is similar to Example 1, except that steps (1) and (2) were not performed, and coaxial powder feeding laser cladding was performed directly on the substrate surface. The laser cladding process parameters were the same as in Example 1.

[0073] Comparative Example 2 Comparative Example 2 is similar to Example 1, except that no metal adhesive was applied in step (2), and all other conditions are the same as in Example 1.

[0074] Test case Average coating thickness: The test was conducted using the system testing software integrated into the ultra-depth-of-field microscope. Five representative measurement points were selected in the central area of ​​the molten pool, with the interval between each measurement point strictly controlled to be greater than 50 μm to maintain independence. The coating thickness data of each point was accurately obtained through the high-precision image analysis function of the microscope. Finally, the system automatically calculated the arithmetic mean of the five measurements as the final average coating thickness of the sample.

[0075] Wear resistance: Wear resistance was tested using the current standard T / GMES 031-2025 Pin / Ball-Disk Friction and Wear Test Part 1: Test Method at Room Temperature. First, the laser-clad sample was machined into a Φ30 mm × 5 mm disc, and a cemented carbide ball (WC-Co) was selected as the grinding pair. The test parameters were set as follows: load 100 N, friction stroke 5 mm, reciprocating frequency 10 Hz (sliding speed 0.1 m / s). Friction tests were conducted under unlubricated conditions, and the coefficient of friction and friction temperature were monitored in real time. After the test, a precision balance was used to measure the mass loss and calculate the wear rate. Each test was repeated three times to ensure data reliability, and the dispersion was required to be controlled within 15%.

[0076] Coating hardness: The microhardness of the coating was measured using an HV1000A Huayin microhardness tester. During the test, the specimen was kept flat, a load of 0.5 kg was applied, and the loading time was 10 s. Since the hardness of diamond is too high to be measured directly, at least 10 test points were randomly selected in the coating near the solder matrix area and the diamond interface area (≤10 μm from the interface). The interval between each point was not less than 0.5 mm, and the arithmetic mean was taken as the final hardness test result of the solder matrix area and the diamond interface area in the composite coating.

[0077] Interfacial bond strength: Following GB / T 44990-2024 "Test Method for Interfacial Bond Strength of Laser Cladding Repair Layers", the interfacial bond strength of the laser cladding coating was evaluated using a micro-specimen tensile method. A pre-fabricated V-notch design was used to enhance the stress concentration effect at the interface. The size of the micro-tensile specimen was reduced to 1 / 2 to 1 / 3 of the standard specimen, and reinforcing blocks (such as ceramic or steel blocks) were bonded to both ends of the specimen to ensure clamping stability. A micro-force testing machine was used, with a loading rate set to 0.5 mm / min for tensile testing. The load-displacement curve was monitored simultaneously, and the average value of three sets of data was taken.

[0078] The test results are shown in Table 1.

[0079] Table 1

[0080] As shown in Table 1, the diamond composite coatings prepared using the combined femtosecond laser pretreatment and laser cladding process (Examples 1-3) exhibit significantly better overall performance than Comparative Example 1, which only uses the conventional laser cladding process. Regarding coating thickness and density, the average coating thickness of all examples (551.05-635.41 μm) is significantly higher than that of Comparative Example 1 (390.83 μm). This demonstrates that the regular pit array (such as hexagonal prisms or cylinders) pre-constructed on the substrate surface by the femtosecond laser can effectively accommodate and anchor more diamond particles and solder, providing an excellent adhesion substrate for the subsequent cladding layer and promoting the formation of a thicker, denser coating.

[0081] Based on the performance comparison, the volumetric wear rate of the embodiment with the better wear resistance is (0.9-1.2×10). -6 mm 3 / N·m) is only comparable to Comparative Example 1 (4.6×10 -6 mm 3 The wear resistance is significantly improved, with the thickness of the coating being approximately 1 / 4 to 1 / 5 of that of the diamond (N·m). This is mainly attributed to the fact that the three-dimensional microstructure formed by femtosecond laser pretreatment enhances the uniformity of the distribution and bonding strength of the hard phase, enabling the coating to exhibit excellent wear resistance under dry sliding friction conditions. Regarding hardness, the microhardness of the brazing filler metal matrix region in the embodiment is higher than that in the comparative example, especially near the diamond / brazing filler metal interface, where the hardness value of the embodiment is significantly increased. This, combined with the microstructure, further illustrates that the femtosecond laser pretreatment promotes the interfacial metallurgical reaction (such as the formation of TiC in Example 3), achieving a strong and tough bond between the hard phase and the matrix. Furthermore, the interfacial bonding strength of the embodiment is significantly better than that of the comparative example. This directly confirms that the micro-pit structure manufactured by femtosecond laser produces a strong mechanical interlocking effect, and combined with the optimized brazing filler metal system, achieves a high-strength metallurgical bond between the coating and the matrix. Data from Example 1 and Comparative Example 2 show that after filling with the first diamond particles, applying a metal binder can significantly improve the performance of the wear-resistant layer.

[0082] As can be seen from the comparison of different embodiments, the morphology (depth, shape, array) of the pits can be effectively controlled by adjusting femtosecond laser parameters (such as power, repetition rate, and scanning strategy), thereby optimizing the coating performance. For example, in Embodiment 3, an active solder was used and matched with a suitable laser power, achieving the best wear resistance (wear rate 0.9) and the highest interface hardness (956.9 HV). 0.2 The results, along with the bonding strength (312.7 MPa), demonstrate the potential for process adjustability and performance optimization.

[0083] like Figure 4 and Figure 5As shown, in this embodiment, the second diamond particles are more evenly and densely distributed, with no brazing filler layer and no cladding powder adhesion. There are virtually no second diamond particles in the adjacent substrate, meaning the diamond particles are less likely to be blown onto the substrate, significantly improving wear resistance. In the comparative example, the number of diamond particles is significantly reduced, with diamond particles appearing in the adjacent substrate, while the intermediate brazing filler layer has no diamond particles. Cladding powder adhesion occurs in all three locations, affecting coating performance. The improved wear resistance in this embodiment is mainly due to the abundance and even distribution of diamond particles; the absence of an intermediate brazing filler layer, direct connection to the substrate, and a thicker coating. Figure 6 and Figure 7 As shown, the coating thickness in the embodiment is increased, the interface is intact, and more diamond particles are encapsulated in the coating; in the comparative example, the diamonds are distributed far from the center of the molten pool, and the distribution is sparse, resulting in an uneven and thinner coating. Figure 8 and Figure 9 As shown, in the microstructure of the embodiment, a carbide layer, a mixture of Cr7C3 and Cr3C2, appears around the diamond, achieving good metallurgical bonding; the coating is intact without cracks. In the microstructure of the comparative example, the diamond is distributed on the coating surface, with less metallurgical bonding; a crack running through the entire coating was found on the other side of the coating. Figure 10 As shown, without the metal binder, some of the first diamond particles were blown away during the laser cladding process. Among the remaining particles, due to density differences and high surface tension, it was difficult to suppress the first diamond particles from floating. They were eventually distributed on the surface or near the surface of the coating in the form of mechanical interlocking. Only a few particles formed a local carbide interface layer with the metal matrix, and the overall metallurgical bonding rate was less than 30%.

[0084] The femtosecond laser pretreatment composite process involved in this invention achieves breakthrough improvements in key performance indicators such as coating thickness, wear resistance, hardness, and interfacial bonding strength through innovative surface microstructure design and process synergy. It comprehensively solves the technical bottlenecks of traditional laser cladding diamond coatings, such as limited thickness, weak bonding force, and insufficient wear resistance, and has significant industrial application value.

[0085] Although the present invention has been illustrated and described with specific embodiments, it should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; those skilled in the art should understand that modifications can be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein, without departing from the spirit and scope of the present invention; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention; therefore, this means that all such substitutions and modifications that fall within the scope of the present invention are included in the appended claims.

Claims

1. A wear-resistant workpiece with a diamond composite coating, characterized in that, The matrix includes a plurality of pits, and at least a portion of the pits contain a first diamond particle. The substrate is provided with a first brazing filler metal, and the first brazing filler metal partially fills the pit and covers the first diamond particle. The first solder is provided with a metal-based diamond composite coating, which includes a second solder and a second diamond particle.

2. The wear-resistant workpiece with a diamond composite coating according to claim 1, characterized in that, It meets at least one of the following characteristics: (1) The particle size of the first diamond particle and the second diamond particle are independently 40-800 mesh; (2) The opening width of the pit is 1-2 times the particle size of the first diamond particle, wherein the opening width refers to the maximum width at the opening of the pit; (3) The depth-to-width ratio of the pit is 0.5-1.5, wherein the depth-to-width ratio refers to the ratio of the depth of the pit to the width of its opening; (4) The spacing between the pits is 1.3-2.5 times the width of the pit opening, wherein the spacing between the pits refers to the distance between the centers of two adjacent pits; (5) The filling rate of the pit is ≥85%.

3. The wear-resistant workpiece with a diamond composite coating according to claim 1 or 2, characterized in that, The morphology of the pit includes at least one of cylindrical, hexagonal prism, and inverted cone shapes; And / or, the arrangement of the pits includes any one of the following: hexagonal close-packed array, rectangular array, circular array, and cross array.

4. The wear-resistant workpiece with a diamond composite coating according to claim 1, characterized in that, It meets at least one of the following characteristics: (1) The first solder includes any one of Ni-based alloy, Cu-based alloy, Co-based alloy, Fe-based alloy, Ag-based alloy, and high-entropy alloy; (2) The thickness of the metal-based diamond composite coating is 0.3-1.2 mm; (3) The second brazing filler metal includes any one of Ni-based alloys, Cu-based alloys, Co-based alloys, Fe-based alloys, Ag-based alloys, and high-entropy alloys; (4) The material of the substrate includes any one of 316L stainless steel, 45# steel, H13 mold steel, and cemented carbide.

5. The method for preparing a wear-resistant workpiece with a diamond composite coating according to any one of claims 1-4, characterized in that, Includes the following steps: S1. Dents are etched on the substrate surface using a femtosecond laser; S2. Fill the pit with the first diamond particle, and coat the pit and the substrate with a metal binder; S3. The second brazing filler powder is mixed with the second diamond particles to obtain a composite powder, and a metal-diamond composite coating is prepared on the surface of the substrate coated with the metal binder by a coaxial powder feeding laser cladding method.

6. The method for preparing a wear-resistant workpiece with a diamond composite coating according to claim 5, characterized in that, The surface of the first diamond particle and / or the second diamond particle is provided with a coating, wherein the coating includes any one of Cr, Ti, Ni, and W.

7. The method for preparing a wear-resistant workpiece with a diamond composite coating according to claim 5, characterized in that, In step S2, the metal binder includes a first solder powder and a liquid medium, wherein the mass percentage of the first solder powder in the metal binder is 50%-90%.

8. The method for preparing a wear-resistant workpiece with a diamond composite coating according to claim 7, characterized in that, It meets at least one of the following characteristics: (1) The first solder powder includes any one of Ni-based alloy powder, Cu-based alloy powder, Co-based alloy powder, Fe-based alloy powder, Ag-based alloy powder, and high-entropy alloy powder; (2) The first brazing filler metal powder contains Ti and / or Cr; (3) The liquid medium includes at least one of ethanol, propylene glycol, water, and water glass.

9. The method for preparing a wear-resistant workpiece with a diamond composite coating according to claim 5, characterized in that, In step S3, at least one of the following characteristics is satisfied: (1) The second solder powder includes any one of Ni-based alloy powder, Cu-based alloy powder, Co-based alloy powder, Fe-based alloy powder, Ag-based alloy powder, and high-entropy alloy powder; (2) The particle size of the second brazing filler metal powder is 45-105 μm; (3) The second diamond particle accounts for 5%-50% of the mass of the composite powder.

10. The method for preparing a wear-resistant workpiece with a diamond composite coating according to any one of claims 5-9, characterized in that, The coaxial powder feeding laser cladding has a powder feeding rate of 5-25 g / min, a laser power of 800-3500 W, a scanning speed of 3-15 mm / s, a spot diameter of 1-3 mm, and an overlap rate of 40%-60%.

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