Laser additive remanufacturing of titanium-based composite coatings, their preparation methods and applications

Abstract

This invention relates to the field of metal additive manufacturing technology, and more particularly to a laser additive remanufacturing titanium-based composite coating, its preparation method, and its application. The method includes: adhering tungsten carbide to nano-sized Mo powder using acoustic resonance technology; preparing the composite coating structure through laser-directed energy deposition and cold spraying; and then relieving stress through heat treatment. This invention adds a composite powder with Mo adhering to the surface of tungsten carbide to TC4 titanium alloy, and then prepares a titanium alloy composite coating using laser-directed energy deposition and cold spraying technology. The adhesion of Mo effectively promotes the transformation of the β phase and acts as a barrier to contact the matrix first, reducing the formation of brittle phases, while simultaneously improving the coating's strength and wear resistance. Heat treatment reduces stress concentration in the coating, increases the diffusion effect of Mo, achieves surface lubrication and friction reduction, and improves the mechanical properties of the titanium alloy composite coating.

Description

Technical Field

[0001] This invention relates to the field of metal additive manufacturing technology, and in particular to a laser additive remanufacturing titanium-based composite coating, its preparation method, and its application. Background Technology

[0002] Titanium alloys, due to their high specific strength, excellent corrosion resistance, and good biocompatibility, occupy an irreplaceable position in the manufacture of key components in aerospace, biomedicine, and energy and chemical industries. These core components, operating under high loads, intense wear, and corrosive environments, such as aero-engine blades and compressor rotors, often fail first due to localized wear, high-temperature oxidation, or contact fatigue, leading to the scrapping of the entire expensive component. To impart surface properties superior to the substrate to the repaired area, especially ultra-high wear resistance and a certain degree of corrosion resistance, WC ceramic particles can significantly improve the coating's hardness and resistance to abrasive wear. However, in actual laser additive manufacturing, the primary challenge is the intense interfacial reaction. Molten titanium undergoes a strong metallurgical reaction with WC particles, inevitably generating brittle TiC, W2C, and complex intermetallic compounds. These brittle phases significantly reduce the coating's toughness, becoming a breeding ground for microcracks, ultimately leading to early spalling or brittle fracture of the coating under service stress. While existing technologies attempt to mitigate this problem by optimizing laser process parameters or adding a pure metal interlayer, they often fail to fundamentally suppress harmful interfacial reactions and may come at the expense of coating performance. Furthermore, traditional mechanical mixing methods, which directly mix ceramic and metal powders, are prone to uneven ceramic phase distribution, burn-off, or spattering during laser processing due to significant differences in density and melting point between the two materials, making it difficult to obtain composite coatings with uniform composition and structure. Therefore, developing a method for preparing titanium-based composite coatings that can effectively control interfacial reactions, achieve uniform ceramic phase distribution, and possess both high strength and high toughness has become a pressing technical challenge in this field. Summary of the Invention

[0003] To address the technical problems existing in the prior art, the present invention aims to provide a laser additive remanufacturing titanium-based composite coating, its preparation method, and its application to solve the aforementioned technical problems. Existing titanium alloys exhibit poor wear resistance, and their overall performance still needs further improvement. Furthermore, the bonding phase between titanium alloys and ceramics has poor wettability, making them prone to cracking, necessitating modification of the ceramic surface. The coating provided by the present invention is a laser additive remanufacturing titanium-based metal and ceramic surface metallization composite coating, possessing excellent wear resistance and mechanical properties.

[0004] To achieve the above-mentioned objectives, the present invention adopts the following technical solution.

[0005] According to a first aspect of the present invention, the present invention provides a laser additive remanufacturing titanium-based composite coating, which, in the building direction, comprises sequentially a TC4 coating (inner layer), a TC4 / WC@Mo composite coating (intermediate layer), and a TC4-Mo coating (surface layer).

[0006] The thickness of the TC4 coating is 0.5-1 mm;

[0007] The TC4 / WC@Mo composite coating is a composite coating of TC4 titanium alloy, tungsten carbide ceramic and Mo metal, with a thickness of 0.5-1mm;

[0008] The TC4-Mo coating is a composite coating of TC4 titanium alloy and Mo metal, with a thickness of 100-300 μm.

[0009] The laser additive remanufacturing titanium-based composite coating provided by this invention is a biomimetic structural composite coating consisting of three layers. The inner layer along the building direction is a pure TC4 coating, the middle layer is a TC4 and WC@Mo composite coating, and the surface layer is a composite coating of TC4 and Mo metal applied by cold spraying. @ indicates composite.

[0010] In some embodiments, the content of WC@Mo composite powder in the TC4 / WC@Mo composite coating is 10-30 wt%, with the remainder being TC4 titanium alloy. The WC@Mo composite powder (a composite powder of tungsten carbide ceramic and Mo metal) is a composite powder prepared from tungsten carbide ceramic and Mo metal, with a mass ratio of tungsten carbide ceramic to Mo metal of 1:2-1:3.

[0011] In some embodiments, the TC4-Mo coating contains 10-30 wt% Mo metal, with the remainder being TC4 titanium alloy.

[0012] According to a second aspect of the present invention, the present invention provides a method for preparing a laser additive remanufacturing titanium-based composite coating, comprising the following steps:

[0013] (1) Prepare TC4 titanium alloy, Mo metal powder and WC ceramic particle powder for later use; mix tungsten carbide ceramic powder and Mo metal powder and perform acoustic resonance treatment (adhere WC ceramic particle powder and Mo metal powder by acoustic resonance technology) to prepare WC@Mo composite powder; add TC4 titanium alloy powder to WC@Mo composite powder and mix well to prepare TC4 / WC@Mo composite powder; mix TC4 titanium alloy powder and Mo metal powder to obtain TC4-Mo composite powder;

[0014] (2) First, a TC4 coating is prepared on the substrate by laser directional energy deposition. Then, a TC4 / WC@Mo composite coating is prepared using the TC4 / WC@Mo composite powder described in step (1). A TC4-Mo coating is prepared on the TC4 / WC@Mo composite coating by cold spraying using the TC4-Mo composite powder described in step (1), thus obtaining a substrate with a composite coating structure.

[0015] (3) The substrate containing the composite coating structure described in step (2) is subjected to heat treatment (heat treatment is used to eliminate stress and further make the Mo element diffuse uniformly) to obtain the laser additive remanufacturing titanium-based composite coating.

[0016] In some embodiments, the particle size of the TC4 titanium alloy powder in step (1) is 45-150 μm, and the particle size of the tungsten carbide ceramic powder (WC ceramic particle powder) is 20-50 μm; in the preparation of WC@Mo composite powder, the particle size of the Mo metal powder used is 50-100 nm; in the preparation of TC4-Mo composite powder, the particle size of the Mo metal powder used is 45-150 μm.

[0017] In some embodiments, the vibration frequency of the acoustic resonance treatment in step (1) is 30-60Hz, the acoustic resonance treatment time is 20-30min, and the acoustic resonance treatment acceleration is 50-80g.

[0018] The acoustic resonance treatment in step (1) involves uniformly and firmly coating a layer of nano-Mo metal powder onto the surface of WC ceramic particles using physical methods, thereby constructing a "core-shell" structured WC@Mo composite powder before laser processing. This treatment utilizes sound waves of a specific frequency to resonate with the powder system, forming an efficient and uniform three-dimensional vibration energy field. This forces the nano-Mo powder, in a fluidized state, to be uniformly coated onto the surface of micron-sized WC particles through van der Waals forces and mechanical meshing effects.

[0019] In some embodiments, the laser power of the laser directional energy deposition in step (2) is 1000-2000W, the laser spot diameter is 1-5mm, the laser scanning speed is 400-1200mm / min, and the overlap rate is 30-70%.

[0020] The acoustic resonance treatment in step (1) involves uniformly and firmly coating the surface of WC ceramic particles with a layer of nano-Mo metal powder using physical methods, thereby constructing a "core-shell" structure of WC@Mo composite powder before laser processing. In the subsequent laser-directed energy deposition process in step (2), the molten TC4 titanium alloy liquid in the laser pool will first come into contact with the Mo coating layer on the surface of the WC particles. Metallic Mo has good compatibility with Ti, and its reaction is far less intense than the reaction between Ti and WC. This dense Mo shell acts as a "chemical barrier," physically isolating the highly reactive Ti melt from the WC core and inhibiting the formation of harmful phases such as brittle TiC and W2C (e.g., Figure 5 (As shown by the light gray isolation layer surrounding WC), thus improving the toughness and bonding strength of the coating from the source. On the other hand, the wettability between metallic Mo and the titanium melt is far superior to that between WC ceramic and the titanium melt. The coating layer improves the wettability of WC particles in the Ti melt, making them easier to be captured and encapsulated by the melt, rather than being repelled or aggregated. Secondly, the nano-Mo coating layer partially dissolves in the titanium matrix under high laser temperature. Mo is a strong and tough β-Ti phase stabilizing element, and its solid solution energy plays a significant solid solution strengthening role, further improving the strength and high-temperature performance of the matrix. In summary, by constructing WC@Mo core-shell structured composite powder, the material system was pre-optimized at the microscale, laying a solid foundation for the subsequent laser preparation of high-performance, low-defect titanium-based composite coatings.

[0021] The laser-directed energy deposition in step (2) is performed using electromagnetic assistance. Since the overall density of the WC@Mo composite powder is greater than that of TC4, electromagnetic assistance is used to control the flow state of the molten pool. This helps to reduce the precipitation of ceramic phase in the molten pool caused by the large density difference, thereby achieving a more uniform distribution of the WC-reinforced phase in the titanium matrix.

[0022] In some embodiments, the spraying temperature of the cold spraying in step (2) is 500-800℃, the spraying pressure of the cold spraying is 4-6MPa, and the spraying speed of the cold spraying is 50-100mm / s.

[0023] The substrate mentioned in step (2) is either a TC4 titanium alloy substrate or a TC17 titanium alloy substrate;

[0024] In some embodiments, the substrate undergoes pretreatment before laser-directed energy deposition. The pretreatment includes grinding, degreasing, derusting, cleaning, and drying of the substrate. Grinding, degreasing, and derusting aim to remove surface oxide scale, oil, and impurities. Cleaning and drying involve cleaning with anhydrous ethanol and then drying.

[0025] In some embodiments, the heat treatment in step (3) is a vacuum heat treatment, with a temperature of 600-1000℃ and a treatment time of 5-8 hours. Heat treatment eliminates stress concentration and improves the service life of the coating. Furthermore, within the β-phase transformation stability temperature range, it can suppress the transformation to the α-phase. Simultaneously, it can effectively enhance the diffusion of Mo and the solid solution of the matrix, thereby improving the strength and toughness of the coating.

[0026] The preparation method provided by the present invention uses electromagnetic assisted field laser directional energy deposition and cold spraying technology to prepare composite structure coatings.

[0027] According to a third aspect of the present invention, the present invention provides the application of laser additive remanufacturing of titanium-based composite coatings in the preparation of aero-engine blades, marine engineering equipment, rail transit equipment, and metallurgical equipment.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] The laser additive remanufacturing titanium-based composite coating provided by this invention, through a sophisticated arrangement of materials and structural gradients, aims to achieve an optimal balance between wear resistance, toughness, and bonding strength, exhibiting superior comprehensive performance. Its core effect stems from the clear division of functions and synergistic effect of each layer. First, the outermost TC4-Mo composite coating (TC4-Mo coating) does not pursue extreme hardness, but rather utilizes Mo's properties as a solid lubricant to significantly reduce the coefficient of friction on the coating surface. This design effectively reduces adhesive wear and frictional heat under dry friction or poor lubrication conditions, thus reducing the wear rate at its source. It provides a unique anti-wear mechanism centered on friction reduction; secondly, the intermediate TC4 and WC@Mo composite coating, as the core load-bearing layer, plays a crucial role. The ultra-hard WC particles provide extremely high compressive strength and resistance to plastic deformation, while the introduction of Mo effectively improves the brittleness of the ceramic phase and enhances the toughness of the layer, making it less prone to cracking under high loads; finally, the pure TC4 coating adjacent to the substrate, as the inner layer, has a chemical composition and thermophysical properties that match the titanium alloy substrate. This not only minimizes residual thermal stress caused by the manufacturing process but also achieves better adhesion between the coating and the substrate. A robust metallurgical bond provides an indispensable and solid foundation for the entire coating system, ensuring its long-term reliability under harsh working conditions. More importantly, this gradient structure of "friction-reducing surface layer - tough intermediate layer - tough bonding layer" mimics the damage resistance mechanism of biological materials, achieving synergistic protection. When subjected to external impact or cyclic loading, the tough surface layer first absorbs some energy through plastic deformation; when the impact energy is transferred to the intermediate tough layer, it is effectively dispersed by WC particles and phase interfaces, inhibiting crack propagation; finally, the tough inner layer acts as the last line of defense, preventing any micro-damage from extending into the matrix. Furthermore, the numerous interfaces between layers can deflect, branch, and passivate any microcracks that may arise, thereby consuming a large amount of energy. This multi-level energy dissipation mechanism gives the coating excellent impact resistance, fatigue resistance, and spalling resistance, effectively overcoming the drawbacks of traditional single hard coatings that are prone to brittle failure. Therefore, this coating design is particularly suitable for fields such as aero-engine blades and key transmission components that have extreme requirements for surface wear resistance and overall impact resistance. It is an advanced and promising solution for the field of surface engineering, and has good application prospects in marine engineering equipment, rail transportation, metallurgy, and other fields. Attached Figure Description

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

[0031] Figure 1This is a flowchart illustrating the preparation of tungsten carbide surface metallization composite powder using acoustic vibration in an embodiment of the present invention.

[0032] Figure 2 This is a front view schematic diagram of the laser additive remanufacturing titanium-based composite coating prepared in an embodiment of the present invention; wherein, 1 is the substrate, 2 is the TC4 coating, 3 is the TC4 / WC@Mo composite coating, 4 is WC particles, 5 is nano-Mo precipitated phase, and 6 is the TC4-Mo cold spray coating.

[0033] Figure 3 This is a top view schematic diagram of the laser additive remanufacturing titanium-based composite coating prepared in an embodiment of the present invention; wherein, 7 represents Mo particles; and 8 represents the Mo diffusion layer;

[0034] Figure 4 The image shows a scanning electron microscope (SEM) image of the TC4-Mo coating prepared by cold spraying in Example 1 of the present invention.

[0035] Figure 5 This is a scanning electron microscope (SEM) image of the TC4-WC@Mo coating prepared by laser-directed energy deposition in Example 1 of the present invention. Detailed Implementation

[0036] To better understand the technical solution of the present invention, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the described embodiments are merely some embodiments of the present invention, and not all embodiments. 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.

[0037] Example 1

[0038] A method for preparing a laser additive remanufacturing titanium-based composite coating includes the following steps:

[0039] (1) Prepare TC4 titanium alloy powder, Mo metal powder and WC ceramic particle powder for later use;

[0040] Reference Figure 1As shown, the preparation of TC4 / WC@Mo composite powder is as follows: Tungsten carbide ceramic powder (i.e., WC ceramic particle powder, with a particle size of 20-50 μm) and Mo metal powder (with a particle size of 50-100 nm) are mixed and subjected to acoustic resonance treatment to adhere the WC ceramic particles to the nano-sized Mo metal powder (i.e., Mo metal powder), thus preparing WC@Mo composite powder; TC4 titanium alloy powder (with a particle size of 45-150 μm) is added to the WC@Mo composite powder and mixed thoroughly to obtain TC4 / WC@Mo composite powder; in the TC4 / WC@Mo composite powder, the mass percentage of WC@Mo composite powder is 30 wt%, and the mass percentage of TC4 titanium alloy powder is 70 wt%.

[0041] Preparation of TC4-Mo composite powder: TC4 titanium alloy powder (particle size 45-150μm) and Mo metal powder (particle size 45-150μm) are mixed to prepare TC4-Mo composite powder; in TC4-Mo composite powder, the mass percentage of Mo metal powder is 30wt%, and the remainder is TC4 titanium alloy powder.

[0042] The vibration frequency of the acoustic resonance treatment in step (1) is 45Hz, the acoustic resonance treatment time is 25min, and the acoustic resonance treatment acceleration is 60g.

[0043] In step (1), during the preparation of WC@Mo composite powder, the mass ratio of WC ceramic particles to nano-metal Mo powder (i.e., Mo metal powder) is 1:2.5.

[0044] (2) First, a TC4 coating is prepared on the substrate 1 by laser directional energy deposition. Then, a TC4 / WC@Mo composite coating is prepared by laser directional energy deposition using the TC4 / WC@Mo composite powder described in step (1). A TC4-Mo coating is prepared on the TC4 / WC@Mo composite coating by cold spraying using the TC4-Mo composite powder described in step (1), thus obtaining a substrate with a composite coating structure.

[0045] In step (2), the laser power for laser-directed energy deposition is 1500W, the laser spot diameter is 3mm, the scanning speed is set to 800 mm / min, and the overlap rate is set to 50%.

[0046] In step (2), the spraying temperature of cold spraying is 600℃, the pressure of cold spraying is 5MPa, and the speed of cold spraying is 80mm / s.

[0047] For example, the substrate in step (2) is TC4 titanium alloy;

[0048] (3) The substrate containing the composite coating structure described in step (2) is subjected to heat treatment (vacuum heat treatment at a temperature of 800°C for 5 hours) to eliminate stress and further make the Mo element diffuse uniformly to obtain the laser additive remanufacturing titanium-based composite coating.

[0049] Reference Figure 2 and Figure 3 As shown, the laser additive remanufacturing titanium-based composite coating prepared in Example 1 has a biomimetic structure and consists of three layers. The inner layer along the building direction is a TC4 coating 2, the middle coating is a TC4 / WC@Mo composite coating 3, and the surface layer is a TC4 / Mo composite coating 6 (TC4-Mo coating) prepared by cold spraying. The thickness of the TC4 coating is 1 mm, the thickness of the TC4 / WC@Mo composite coating is 1 mm, and the thickness of the TC4-Mo composite coating is 200 μm. From a top-view angle (e.g.) Figure 3 As shown), the surface of the TC4 and Mo composite coating 6 has Mo particles 7, and a Mo diffusion layer 8 exists around the Mo particles. In the TC4 and WC@Mo composite coating 3 (TC4 / WC@Mo composite coating), WC particles 4 and nano-Mo precipitates 5 are present.

[0050] Figure 4 This is a scanning electron microscope (SEM) image of the TC4-Mo coating prepared by cold spraying in Example 1 of this invention; Figure 4 It can be seen that the Mo particles are relatively uniformly distributed and have formed a good bond with the matrix phase through plastic deformation.

[0051] Figure 5 This is a scanning electron microscope (SEM) image of the TC4-WC@Mo coating prepared by laser-directed energy deposition in Example 1 of the present invention. Figure 5 It can be seen that a 1-2 μm isolation layer is formed around the WC particles. This isolation layer can further prevent the precipitation of brittle phase and enhance the bonding strength between WC and the matrix phase.

[0052] Example 2

[0053] Example 2 provides a laser additive remanufacturing titanium-based composite coating and its preparation method. The difference between this example and Example 1 is as follows:

[0054] The laser-directed energy deposition process and cold spraying parameters were adjusted as follows: laser power 1000W, laser spot diameter 1mm, laser scanning rate 400 mm / min, overlap rate 50%, while the cold spraying temperature was 500℃, the cold spraying pressure was 4MPa, and the cold spraying speed was 50 mm / s. The rest were the same as in Example 1.

[0055] Example 3

[0056] Example 3 provides a laser additive remanufacturing titanium-based composite coating and its preparation method. The difference between this example and Example 1 is as follows:

[0057] The laser-directed energy deposition process and cold spraying parameters were adjusted as follows: laser power 2000W, laser spot diameter 5mm, laser scanning rate 1200 mm / min, overlap rate 50%, while the cold spraying temperature was 800℃, the cold spraying pressure was 6MPa, and the cold spraying speed was 100 mm / s. The rest were the same as in Example 1.

[0058] Example 4

[0059] Example 4 provides a laser additive remanufacturing titanium-based composite coating and its preparation method. The difference between this example and Example 1 is that the vacuum heat treatment temperature is 600℃ and the time is 5 hours. The rest is the same as in Example 1.

[0060] Example 5

[0061] Example 5 provides a laser additive remanufacturing titanium-based composite coating and its preparation method. The difference between this example and Example 1 is that the vacuum heat treatment temperature is 1000℃ and the time is 8 hours. The rest is the same as in Example 1.

[0062] Example 6

[0063] Example 6 provides a laser additive remanufacturing titanium-based composite coating and its preparation method. The difference between this example and Example 1 is that the amount of Mo added in the TC4-Mo composite powder is 10 wt.%; while in the TC4 / WC@Mo composite powder, the amount of WC@Mo composite powder added is 10 wt.%. The rest is the same as in Example 1.

[0064] Example 7

[0065] Example 7 provides a laser additive remanufacturing titanium-based composite coating and its preparation method. The difference between this example and Example 1 is that the amount of Mo added in the TC4-Mo composite powder is 20 wt.%; while in the TC4 / WC@Mo composite powder, the amount of WC@Mo composite powder added is 20 wt.%. The rest is the same as in Example 1.

[0066] Example 8

[0067] Example 8 provides a laser additive remanufacturing titanium-based composite coating and its preparation method. The difference between this example and Example 1 is that the thickness of the TC4 coating is 0.5 mm, the thickness of the TC4 / WC@Mo composite coating is 0.5 mm, and the thickness of the TC4 / Mo composite coating is 100 μm. The rest is the same as in Example 1.

[0068] Comparative Example 1

[0069] Comparative Example 1 provides a coating and its preparation method. The difference between Comparative Example 1 and Example 1 is that the coating is only a single layer of TC4 coating, and the preparation process of the TC4 coating is carried out in accordance with Example 1.

[0070] Comparative Example 2

[0071] Comparative Example 2 provides a coating and its preparation method. The difference between Comparative Example 2 and Example 1 is that the coating includes a two-layer structure, namely, a TC4 coating and a TC4-Mo coating sequentially from the building direction, but without the intermediate TC4 and WC@Mo composite coating. The preparation processes of the TC4 coating and the TC4-Mo coating are the same as in Example 1.

[0072] Comparative Example 3

[0073] Comparative Example 3 provides a coating and its preparation method. The only difference between Comparative Example 3 and Example 1 is that the coating comprises a two-layer structure, namely, from the building direction, it includes a TC4 / WC@Mo composite coating and a TC4-Mo coating, but without an inner TC4 coating. The preparation processes for the TC4 / WC@Mo composite coating and the TC4-Mo coating are the same as in Example 1.

[0074] Comparative Example 4

[0075] Comparative Example 4 provides a coating and its preparation method. The only difference between Comparative Example 4 and Example 1 is that the coating comprises a two-layer structure, consisting of a TC4 coating and a TC4 / WC@Mo composite coating (TC4 / WC@Mo composite coating) sequentially from the building direction, but without an outer cold-sprayed TC4 / Mo coating. The preparation processes for the TC4 coating and the TC4 / WC@Mo composite coating are the same as in Example 1.

[0076] Comparative Example 5

[0077] Comparative Example 5 provides a coating and its preparation method. The difference between Comparative Example 5 and Example 1 is that the amount of Mo added in the TC4-Mo composite powder is 40 wt.%; while in the TC4 / WC@Mo composite powder, the amount of WC@Mo composite powder added is 40 wt.%. All other aspects are the same as in Example 1.

[0078] Comparative Example 6

[0079] Comparative Example 6 provides a coating and its preparation method. The difference between Comparative Example 6 and Example 1 is that the laser-directed energy deposition process parameters are adjusted to a laser power of 800 W and a scanning speed of 1200 mm / min. All other parameters are the same as in Example 1.

[0080] Comparative Example 7

[0081] Comparative Example 7 provides a coating and its preparation method. The difference between Comparative Example 7 and Example 1 is that the cold spraying process parameters are adjusted to a spraying temperature of 300°C, a spraying pressure of 3 MPa, and a spraying speed of 50 mm / s. All other parameters are the same as in Example 1.

[0082] Comparative Example 8

[0083] Comparative Example 8 provides a coating and its preparation method. The difference between Comparative Example 8 and Example 1 is that the intermediate layer is changed to a TC4-Mo coating obtained by cold spraying, and the surface layer is changed to a TC4 / WC@Mo composite coating. All other aspects are the same as in Example 1.

[0084] Comparative Example 9

[0085] Comparative Example 9 provides a coating and its preparation method. The only difference between Comparative Example 9 and Example 1 is that no heat treatment is performed in step (3). All other aspects are the same as in Example 1.

[0086] Comparative Example 10

[0087] Comparative Example 10 provides a coating and its preparation method. The only difference between Comparative Example 10 and Example 1 is that the particle size of the Mo powder used in the preparation of the WC@Mo composite powder is 45-150 μm. All other aspects are the same as in Example 1.

[0088] Comparative Example 11

[0089] Comparative Example 11 provides a coating and its preparation method. The only difference between Comparative Example 10 and Example 1 is that, in the preparation process of the WC@Mo composite powder, acoustic resonance technology is not used to mix the tungsten carbide ceramic powder (WC ceramic particle powder) and the Mo metal powder. Instead, stirring is used to mix the two evenly. All other aspects are the same as in Example 1.

[0090] Effect verification

[0091] The coatings prepared in each embodiment and comparative example were tested using the methods described below. The test results are shown in Table 1 below.

[0092] Wear performance test method: determined according to national standard GB / T 43853-2024;

[0093] Test method for Charpy pendulum impact performance: Determined according to national standard GB / T 229-2020;

[0094] Forming quality: The cross-sections and surface forming quality of each coating were observed using a Leica DmirmMW-550 metallographic microscope.

[0095] Table 1 Test Results

[0096]

[0097] The test data (Table 1) shows that Comparative Example 1, containing only one layer of TC4, has low surface hardness, resulting in poor wear resistance; Comparative Example 2 lacks an intermediate high-strength coating, leading to a decrease in its impact resistance; Comparative Example 3, lacking the transitional effect of the inner TC4 layer, experienced cracking during coating preparation, resulting in a severe decrease in impact resistance; Comparative Example 4, lacking an outer layer of high-toughness cold-sprayed TC4 / Mo coating, experienced a decrease in impact resistance; Comparative Example 5, with excessive Mo addition, experienced coating cracking and decreased impact resistance; Comparative Examples 6 and 7... The process parameters of Comparative Example 8 were insufficient to form the coating; in Comparative Example 8, the cold-sprayed TC4 / Mo coating bonded to the substrate through deformation, and when adjusted to the intermediate layer, a large amount of concentrated stress occurred, leading to coating cracking and affecting its impact performance; in Comparative Example 9, due to the lack of heat treatment, the diffusion effect of Mo elements in the surface layer was poor, resulting in a weakened friction-reducing effect and an increased friction coefficient; in Comparative Examples 10 and 11, the large-particle-size Mo powder could not adhere to the WC particles, causing Mo to be unable to prevent further dissolution of WC during the coating preparation process, generating more brittle phases that led to coating cracking and reduced performance. In contrast, the laser additive remanufacturing titanium-based composite coating provided in this invention has good coating forming quality and is defect-free.

[0098] In summary, the laser additive remanufacturing titanium-based composite coating provided in this embodiment of the invention is a composite structure coating. This three-layer design, through a sophisticated arrangement of materials and structural gradients, aims to achieve an optimal balance between wear resistance, toughness, and bonding strength, exhibiting superior comprehensive performance. Its core effect stems from the clear division of functions and synergistic effect of each layer. First, the outermost TC4 and Mo composite coating does not pursue extreme hardness, but rather utilizes Mo's properties as a solid lubricant to significantly reduce the coefficient of friction on the coating surface. This design effectively reduces adhesive wear and frictional heat under dry friction or poor lubrication conditions, reducing the wear rate at its source and providing a unique anti-wear mechanism centered on friction reduction. Second, the middle TC4 and WC@Mo composite coating, as the core load-bearing layer, plays a crucial role. The ultra-hard WC particles provide extremely high compressive strength and resistance to plastic deformation, while the introduction of Mo effectively improves the brittleness of the ceramic phase and enhances the toughness of the layer, making it less prone to cracking under high loads. Finally, the pure TC4 coating adjacent to the substrate serves as the inner layer. Its chemical composition and thermophysical properties are perfectly matched with the titanium alloy substrate. This not only minimizes the residual thermal stress caused by the preparation process, but also achieves a strong metallurgical bond with the substrate, providing an indispensable and solid foundation for the entire coating system and ensuring its long-term service reliability under harsh working conditions.

[0099] The above descriptions are merely some embodiments of the present invention. Those skilled in the art can make various modifications and improvements without departing from the inventive concept of the present invention, and these all fall within the scope of protection of the present invention.

Claims

1. A laser additive remanufacturing titanium-based composite coating, characterized in that, From the architectural direction, the coatings are TC4 coating, TC4 / WC@Mo composite coating, and TC4-Mo coating. The thickness of the TC4 coating is 0.5-1 mm; The TC4 / WC@Mo composite coating is a composite coating of TC4 titanium alloy, tungsten carbide ceramic and Mo metal, with a thickness of 0.5-1mm; The TC4-Mo coating is a composite coating of TC4 titanium alloy and Mo metal, with a thickness of 100-300 μm; In the TC4-Mo coating, the content of Mo metal is 10-30 wt%, and the remainder is TC4 titanium alloy.

2. The laser additive remanufacturing titanium-based composite coating according to claim 1, characterized in that, In the TC4 / WC@Mo composite coating, the content of WC@Mo composite powder is 10-30wt%, and the remainder is TC4 titanium alloy; the WC@Mo composite powder is a composite powder prepared by tungsten carbide ceramic and Mo metal, and the mass ratio of tungsten carbide ceramic to Mo metal is 1:2-1:

3.

3. The method of producing a laser additive remanufacturing titanium-based composite coating according to any one of claims 1-2, characterized in that, Includes the following steps: (1) Mix tungsten carbide ceramic powder and Mo metal powder, and perform acoustic resonance treatment to prepare WC@Mo composite powder; add TC4 titanium alloy powder to WC@Mo composite powder and mix well to obtain TC4 / WC@Mo composite powder; mix TC4 titanium alloy powder and Mo metal powder to prepare TC4-Mo composite powder. (2) First, a TC4 coating is prepared on the substrate by laser directional energy deposition. Then, a TC4 / WC@Mo composite coating is prepared using the TC4 / WC@Mo composite powder described in step (1). A TC4-Mo coating is prepared on the TC4 / WC@Mo composite coating by cold spraying using the TC4-Mo composite powder described in step (1), thus obtaining a substrate with a composite coating structure. (3) The substrate containing the composite coating structure described in step (2) is subjected to heat treatment to obtain the laser additive remanufacturing titanium-based composite coating; In the preparation of the WC@Mo composite powder in step (1), the Mo metal powder used has a particle size of 50-100 nm; In step (2), the laser power for laser-directed energy deposition is 1000-2000W, the laser spot diameter is 1-5mm, the laser scanning speed is 400-1200mm / min, and the overlap rate is 30-70%. The spraying temperature of the cold spraying in step (2) is 500-800℃, the spraying pressure is 4-6MPa, and the spraying speed is 50-100mm / s.

4. The method of claim 3, wherein the laser additive remanufacturing of the titanium-based composite coating is performed by a laser additive manufacturing method. The particle size of the TC4 titanium alloy powder in step (1) is 45-150 μm, and the particle size of the tungsten carbide ceramic powder is 20-50 μm; in the preparation of the TC4-Mo composite powder, the particle size of the Mo metal powder used is 45-150 μm.

5. The method for preparing a laser additive remanufacturing titanium-based composite coating according to claim 3, characterized in that, The vibration frequency of the acoustic resonance treatment in step (1) is 30-60Hz, the acoustic resonance treatment time is 20-30min, and the acoustic resonance treatment acceleration is 50-80g.

6. The method for preparing a laser additive remanufacturing titanium-based composite coating according to claim 3, characterized in that, The heat treatment method described in step (3) is vacuum heat treatment, the heat treatment temperature is 600-1000℃, and the heat treatment time is 5-8 hours.

7. The application of the laser additive remanufacturing titanium-based composite coating according to any one of claims 1-2 in the preparation of aero-engine blades, marine engineering equipment, rail transit equipment, and metallurgical equipment.

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