A method of additive manufacturing of a tungsten carbide reinforced titanium-aluminum alloy wear resistant coating and a method of manufacture

Abstract

This invention provides an additive manufacturing method for a tungsten carbide-reinforced titanium-aluminum alloy wear-resistant coating, relating to the technical field of additive manufacturing of titanium-aluminum alloys. The chemical composition, by atomic percentage, is: W 0.5-10 at%, C 0.5-10 at%, Al 40-46 at%, Nb 4-10 at%, Ta 1-4 at%, Mo 0.1-0.9 at%, B 0.25-0.75 at%, oxygen content below 600 ppm, with the balance being Ti and unavoidable impurity elements. The preparation method includes ball milling and powder mixing, directional energy deposition additive manufacturing, stress-relief annealing, and solution aging treatment. This invention addresses the problems of existing technologies, such as easy cracking of coatings on large-size components, low bonding strength between the coating and the substrate, high wear rate, difficulty in adapting to complex-shaped components, and ultimately, the inability to stably prepare high-performance wear-resistant coatings.

Description

Technical Field

[0001] This invention relates to the technical field of wear-resistant coating preparation, and more particularly to an additive manufacturing method for a tungsten carbide reinforced titanium-aluminum alloy wear-resistant coating. Background Technology

[0002] Titanium-aluminum alloys are widely used in aerospace (such as engine turbine blades and combustion chamber components), automotive (such as turbocharger rotors), and energy (such as high-temperature heat exchangers). In these applications, components must withstand long-term high-temperature airflow erosion, particle friction, and fretting wear between components. However, titanium-aluminum alloys themselves have low hardness, and their inherent wear resistance is far from meeting service requirements. Therefore, it is necessary to improve surface properties by preparing wear-resistant coatings. Currently, traditional methods for preparing titanium-aluminum wear-resistant coatings have significant limitations. Although physical vapor deposition (PVD) and chemical vapor deposition (CVD) can form dense coatings, their thickness is only a few micrometers to tens of micrometers, they are easily worn through, and the coating has weak adhesion to the substrate, making it difficult to adapt and form complex components.

[0003] Additive manufacturing technologies (such as powder bed fusion EBM, SLM, and directional energy deposition DED) have shown potential in the preparation of wear-resistant coatings for titanium-aluminum alloys, but currently still have the following shortcomings: the tendency for coatings to crack on large-size components remains high; at the same time, there is still room for improvement in the bonding strength between the coating and the substrate, making it difficult to meet the requirements of use under extreme conditions. The residual stress after deposition is not sufficiently eliminated, the bonding strength between the coating and the substrate is still not ideal, and the wear rate is relatively high, making it difficult to meet the stringent requirements for the comprehensive performance of coatings in aerospace and other fields.

[0004] Therefore, developing a high-performance wear-resistant coating that can overcome the above-mentioned defects and is suitable for titanium-aluminum alloy parts has become an urgent technical problem to be solved in this field. Summary of the Invention

[0005] Based on the above analysis, the present invention aims to provide an additive manufacturing method for a wear-resistant coating of tungsten carbide reinforced titanium-aluminum alloy, which solves at least one of the problems of existing technologies, such as easy cracking of coatings on large-size parts, low bonding strength between coating and substrate, high wear rate, difficulty in adapting to complex-shaped parts, and ultimately inability to stably prepare high-performance wear-resistant coatings.

[0006] On the one hand, the present invention provides an additive manufacturing tungsten carbide reinforced titanium-aluminum alloy wear-resistant coating, the chemical composition of which, by atomic percentage, is: W 0.5-10at%, C 0.5-10at%, Al 40-46at%, Nb 4-10at%, Ta 1-4at%, Mo 0.1-0.9at%, B 0.25-0.75at%, oxygen content less than 600ppm, and the balance being Ti and unavoidable impurity elements.

[0007] Furthermore, the wear-resistant coating contains an in-situ generated WC reinforcing phase.

[0008] Furthermore, the wear-resistant coating is prepared by additive manufacturing using powder, which includes titanium-aluminum alloy powder and tungsten carbide powder. The titanium-aluminum alloy powder has a particle size of 50~150μm, and the tungsten carbide powder has a particle size of 15~40μm.

[0009] On the other hand, the present invention provides a method for preparing an additive manufacturing tungsten carbide reinforced titanium-aluminum alloy wear-resistant coating, comprising the following four steps: S1. Titanium-aluminum alloy powder and tungsten carbide reinforcing phase powder are mixed by ball milling; S2. A wear-resistant coating is formed by depositing mixed powders onto the surface of titanium-aluminum alloy parts using a laser-directed energy deposition (EDD) device. S3. Perform stress-relief annealing on the deposited components; S4. After annealing, perform solution treatment and aging.

[0010] Furthermore, S1. The ball milling method uses an argon-protected planetary ball mill for powder mixing, and the tungsten carbide powder should not exceed 10% of the total volume of the powder after mixing.

[0011] Furthermore, in S1, the ball milling method uses yttrium oxide or zirconium oxide milling balls with a ball-to-material ratio of 3:1 to 5:1. Before ball milling, the material is washed and purged with argon. The ball milling time is 12-24 hours, and a water chiller is used for process cooling at a rate of 4-6°C / min. After ball milling, a vibrating screen is used to remove unbound fine powder.

[0012] Furthermore, in S2, when the laser-directed energy deposition equipment is used to apply the wear-resistant coating, the laser power is 500~800W, the laser spot diameter is 2~3mm, the laser moving speed is 10~30mm / s, the deposition layer thickness is 0.5~0.8mm, the powder hopper feeder speed is 50~100 r / min, and the argon gas delivery rate is 6~10L / min.

[0013] Furthermore, in S2, when using laser-directed energy deposition equipment to deposit wear-resistant coatings on parts, rotary cladding is used for shaft-type titanium-aluminum alloy parts, and planar cladding is used for plate-type titanium-aluminum alloy parts; an in-situ preheating control strategy is used to ensure uniform temperature rise across the entire surface of the part, when the part volume or cladding surface area is greater than 50 cm². 2 In addition, induction heating is required to raise the temperature of the titanium-aluminum alloy parts to above the ductile-brittle transition temperature.

[0014] Furthermore, in S3, the workpiece is immediately removed after deposition and placed in a muffle furnace for stress-relief annealing. The holding temperature is not lower than 600°C and the holding time is not lower than 24 hours. After annealing, the workpiece is cooled in the furnace and removed when the temperature is lower than 50°C.

[0015] Furthermore, in S4, the solution treatment temperature is 1300~1360℃, and the holding time is 2~4h; the aging treatment temperature is 840-860℃, and the holding time is 6~8h.

[0016] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects: 1. The tungsten carbide-reinforced titanium-aluminum alloy wear-resistant coating of the present invention is a multi-component synergistic strengthening tungsten carbide-reinforced titanium-aluminum alloy material system. This coating uses titanium-aluminum alloy as the matrix and constructs a multi-component synergistic strengthening material system through the atomic percentages of elements such as W, C, Al, Nb, Ta, Mo, and B, as well as the oxygen content. By precisely controlling the atomic ratio of W to C (0.5-10 at%), a WC hard reinforcing phase is generated in situ during laser cladding. The WC particles act as a "wear-resistant skeleton," increasing the coating hardness to 1300-1500 HV. Simultaneously, through multi-component solid solution strengthening of Nb (4-10 at%), Ta (1-4 at%), and Mo (0.1-0.9 at%), the high-temperature oxidation resistance, creep resistance, and matrix strength of the coating are significantly improved. The addition of B (0.25-0.75 at%) refines the grain structure and improves the coating toughness. The oxygen content is strictly controlled below 600 ppm to avoid brittle oxide inclusions. The synergistic effect of this multi-layered reinforcement system enables the coating to achieve ultra-high hardness while maintaining good toughness and wear resistance.

[0017] 2. The four steps of this invention work synergistically to systematically solve the industry problems of easy cracking, weak bonding, and poor wear resistance of titanium-aluminum alloy coatings, ultimately achieving a hardness of 1300-1500 HV, a bonding strength of 85-90 MPa, and a wear rate as low as 3×10⁻⁶. -5 -8×10 -5 High-performance coating with a thickness of mm³ / (N·m).

[0018] 3. In this invention, when applying a wear-resistant coating using a laser-directed energy deposition (LDED) device, a laser is used as a heat source to simultaneously melt and deposit the titanium-aluminum alloy substrate and the wear-resistant alloy powder layer by layer. The laser power is 500~800W, the laser spot diameter is 2~3mm, the laser moving speed is 10~30mm / s, the deposition layer thickness is 0.5~0.8mm, the powder hopper feeder speed is 50~100 r / min, and the argon gas delivery rate is 6~10L / min. The parameters of the powder hopper feeder and the LED device are precisely matched to achieve a stable molten pool, good interface bonding, no unmelted particles, and a dispersed distribution of the tungsten carbide reinforcing phase, thereby enhancing the bonding strength and hardness.

[0019] 4. This invention utilizes laser-directed energy deposition technology, using a laser as a heat source to simultaneously melt and layer-by-layer deposit titanium-aluminum alloy substrate and wear-resistant alloy powder, combined with in-situ preheating control (e.g., when the component volume or cladding surface is greater than 50cm). 2 Furthermore, induction heating is required to raise the titanium-aluminum alloy components to above the ductile-brittle transition temperature to suppress thermal stress cracking and solve the problems of uneven coating on complex-shaped components and thermal stress cracking in large-sized components. Simultaneously, lasers are used to melt the substrate and powder synchronously, achieving a metallurgical-grade bond between the coating and the substrate, with a bonding strength far exceeding that of traditional physical bonding.

[0020] 5. The present invention performs stress-relief annealing after coating deposition, which allows the titanium-aluminum alloy to undergo microscopic plastic deformation through creep and dislocation reorganization, thereby effectively relaxing (eliminating) residual stress and preventing coating cracks.

[0021] 6. The solution treatment of this invention maximizes the dissolution of alloying elements such as W, C, Nb, Ta, and Mo, forming a highly supersaturated solid solution, which provides a foundation for subsequent aging strengthening. The holding time ensures compositional homogenization and avoids microsegregation. This step is a prerequisite for the precipitation of fine strengthening phases during subsequent aging, directly affecting the final hardness and wear resistance of the coating. The aging treatment promotes the precipitation of fine and dispersed strengthening phases (such as WC and carbides) from the supersaturated solid solution, achieving a "peak aging" state and realizing peak hardness (1300-1500 HV) and optimal wear resistance; at the same time, it avoids the formation of brittle phases and maintains the toughness of the coating. This parameter window is closely coupled with the solution treatment, jointly transforming the material's strengthening potential into the final performance.

[0022] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0023] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0024] Figure 1 is a flowchart of a method for preparing a wear-resistant coating of tungsten carbide reinforced titanium-aluminum alloy by additive manufacturing according to the present invention; Figure 2 This is a schematic diagram of the structure of an additively manufactured tungsten carbide reinforced titanium-aluminum alloy wear-resistant coating according to the present invention; Figure 3 The image shows the SEM morphology of the coating cross-section in Example 1.

[0025] Figure label: Figure 2 1. Tungsten carbide core; 2. Tungsten carbide and titanium-aluminum transition zone; 3. Wear-resistant coating; 4. Coating-substrate bonding layer; 5. Titanium-aluminum component substrate. Detailed Implementation

[0026] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0027] Titanium-aluminum alloys are widely used in aerospace (e.g., engine turbine blades, combustion chamber components), automotive (e.g., turbocharger rotors), and energy (e.g., high-temperature heat exchangers). In these applications, components must withstand long-term high-temperature airflow erosion, particle friction, and fretting wear between components. However, titanium-aluminum alloys themselves have relatively low hardness, and their inherent wear resistance is far from meeting service requirements. Therefore, it is essential to improve surface properties through the preparation of wear-resistant coatings. Existing technologies suffer from problems such as easy cracking of coatings on large-sized components, low adhesion strength between the coating and the substrate, high wear rates, and difficulty in adapting to complex-shaped components, ultimately hindering the stable preparation of high-performance wear-resistant coatings.

[0028] Therefore, on the one hand, the present invention provides an additive manufacturing tungsten carbide reinforced titanium-aluminum alloy wear-resistant coating, the chemical composition of which, by atomic percentage, is: W 0.5-10at%, C 0.5-10at%, Al 40-46at%, Nb 4-10at%, Ta 1-4at%, Mo 0.1-0.9at%, B 0.25-0.75at%, oxygen content less than 600ppm, and the balance being Ti and unavoidable impurity elements.

[0029] Furthermore, the wear-resistant coating contains an in-situ generated WC reinforcing phase.

[0030] The wear-resistant coating contains an in-situ generated WC reinforcing phase, which is directly formed by the W and C elements in the raw material powder through a chemical reaction, dispersed and precipitated, and finally solidified in the titanium-aluminum matrix. The in-situ generated WC has a direct atomic bond with the surrounding titanium-aluminum matrix, without an oxide film or impurity interface, thus resulting in higher bonding strength, making it less prone to peeling off during wear, and exhibiting a pure interface and strong bonding.

[0031] The tungsten carbide-reinforced titanium-aluminum alloy wear-resistant coating of the present invention is a multi-component synergistic strengthening tungsten carbide-reinforced titanium-aluminum alloy material system. This coating uses titanium-aluminum alloy as the matrix and constructs a multi-component synergistic strengthening material system through the atomic percentages of elements such as W, C, Al, Nb, Ta, Mo, and B, as well as the oxygen content. By precisely controlling the atomic ratio of W to C (0.5-10 at%), a WC hard reinforcing phase is generated in situ during laser cladding. The WC particles act as a "wear-resistant skeleton," increasing the coating hardness to 1300-1500 HV. Simultaneously, through multi-component solid solution strengthening of Nb (4-10 at%), Ta (1-4 at%), and Mo (0.1-0.9 at%), the high-temperature oxidation resistance, creep resistance, and matrix strength of the coating are significantly improved. The addition of B (0.25-0.75 at%) refines the grain structure and improves the coating toughness. The oxygen content is strictly controlled below 600 ppm to avoid brittle oxide inclusions. The synergistic effect of this multi-layered reinforcement system enables the coating to achieve ultra-high hardness while maintaining good toughness and wear resistance. For example... Figure 2 As shown, the coating structure exhibits characteristics of dispersed distribution of reinforcing phase, good interfacial bonding, and dense, defect-free structure. Figure 3 The SEM cross-sectional morphology further verified the tight metallurgical bond between the coating and the substrate.

[0032] Specifically, the roles of each element and the reasons for their dosage are as follows: W: W is one of the core contributors to the wear resistance of this coating, combining with C to form a WC (tungsten carbide) reinforcing phase. Furthermore, W itself is a strong solid solution strengthening element. The lower limit of 0.5 at% is the minimum requirement to produce an effective enhanced wear resistance effect; the upper limit of 10 at% is to avoid excessive WC leading to a sharp increase in coating brittleness and deterioration of laser cladding processability (such as poor melt flow). Therefore, the W content range is 0.5-10 at%. For example, W contents are 0.5 at%, 1 at%, 2 at%, 3 at%, 4 at%, 5 at%, 6 at%, 7 at%, 8 at%, 9 at%, and 10 at%.

[0033] C: The main function of C is to combine with W to form a WC reinforcing phase in situ. Simultaneously, trace amounts of C dissolved in the matrix also exert a significant reinforcing effect. Therefore, the C content ranges from 0.5-10 at%, with examples including 0.5 at%, 1 at%, 2 at%, 3 at%, 4 at%, 5 at%, 6 at%, 7 at%, 8 at%, 9 at%, and 10 at%.

[0034] Al content is directly related to the high-temperature stability and crack propagation resistance of the matrix. Too low or too high an Al content will lead to a decrease in hardness and bond strength. Therefore, the Al content range is 40-46 at%, for example, 40 at%, 41 at%, 42 at%, 43 at%, 44 at%, 45 at%, and 46 at%.

[0035] Ti: As a matrix element, it forms ordered intermetallic compounds with Al, providing the basic structural framework and mechanical properties.

[0036] Nb: Its core function is to significantly improve high-temperature oxidation resistance and high-temperature strength. Too much or too little Nb will lead to embrittlement. Therefore, the Nb content range is 4-10 at%. For example, the Nb content is 4 at%, 5 at%, 6 at%, 7 at%, 8 at%, 9 at%, and 10 at%.

[0037] Ta: It can further improve the creep resistance and strength of the alloy. It is controlled within a low range of 1-4 at%, serving as a supplementary strengthening element to Nb, avoiding excessive increases in density and cost. Therefore, the Tb content ranges from 1-4 at%, for example, Ta content is 1 at%, 2 at%, 3 at%, and 4 at%.

[0038] Mo: Mo is an important solid solution strengthening agent. It can effectively improve the room temperature and high temperature strength of alloys and enhance creep resistance. Its content is controlled below 0.9 at%, because excessive Mo content can introduce harmful substances that impair the room temperature plasticity and hot deformation ability of the alloy.

[0039] B: The refining effect of boron (B) helps improve coating toughness, indirectly enhancing bonding strength and wear resistance. Too low a content results in insufficient refining, while too high a content may lead to the formation of coarse primary TiB2, which can become a crack initiation point. Therefore, the B content range is 0.25-0.75 at%. For example, B contents are 0.25 at%, 0.35 at%, 0.45 at%, 0.55 at%, 0.65 at%, and 0.75 at%.

[0040] Excessive O:O content can easily lead to fatigue problems and increased wear. Beyond a certain limit, it can form hard and brittle oxide inclusions and promote the precipitation of harmful phases. An O content below 600 ppm ensures that the coating achieves high hardness while retaining sufficient toughness to prevent brittle fracture.

[0041] Furthermore, the wear-resistant coating is prepared using additive manufacturing with powder, the powder comprising titanium-aluminum alloy powder and tungsten carbide powder, wherein the titanium-aluminum alloy powder has a particle size of 50-150 μm and the tungsten carbide powder has a particle size of 15-40 μm. Both powders can be prepared using the EIGA or PREP methods.

[0042] The particle size mentioned here refers to the particle size of the powder used for mixing, which is then subjected to laser cladding. It does not refer to the particle size of the powder in the coating itself, which is formed through melting and solidification. When using powder additive manufacturing to prepare a coating, the chemical composition of the powder directly determines the chemical composition of the wear-resistant coating. Titanium-aluminum alloy powder with a particle size of 50~150μm ensures good flowability and powder feeding stability. Powders within this particle size range have suitable bulk density and flowability, enabling continuous and stable conveying through a powder feeding system. Examples of titanium-aluminum alloy powder particle sizes include 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, 110μm, 120μm, 130μm, 140μm, and 150μm. Tungsten carbide powder with a particle size of 15-40 μm, exemplarily 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, and 40 μm, serves as a hard reinforcing phase. Tungsten carbide needs to be dispersed as finely and uniformly as possible within the titanium-aluminum matrix. Fine particles of 15-40 μm are more easily embedded or adhered to the surface of larger titanium-aluminum powders through mechanical action during subsequent ball milling, forming a "pre-composite" powder, thus achieving in-situ uniform distribution during laser cladding. Controlling the tungsten carbide powder particle size to 15-40 μm and the titanium-aluminum powder particle size to 50-150 μm helps maintain mixing uniformity during airflow powder feeding and deposition. If the powder is too fine, it is prone to agglomeration, clogging the nozzle, and being easily dispersed by the protective airflow; if it is too coarse, the flowability deteriorates, resulting in uneven powder feeding. Both powders can be prepared using the EIGA or PREP methods, which can ensure powder purity (low oxygen, low impurities) and can stably produce powders that meet the specifications of 50-150μm and 15-40μm.

[0043] On the other hand, the present invention provides an additive manufacturing method for a wear-resistant coating of tungsten carbide reinforced titanium-aluminum alloy, comprising the following four steps: S1. Titanium aluminum alloy powder and tungsten carbide powder are mixed by ball milling to obtain a mixed powder; S2. A wear-resistant coating is formed by depositing mixed powders onto the surface of titanium-aluminum alloy parts using a laser-directed energy deposition (EDD) device. S3. Perform stress-relief annealing on the deposited components; S4. After stress-relief annealing, perform solution treatment and aging treatment.

[0044] The present invention provides a method for preparing a tungsten carbide reinforced titanium-aluminum alloy wear-resistant coating, which systematically solves the problems of easy cracking of coatings on large-size parts, low bonding strength between coating and substrate, high wear rate, difficulty in adapting to complex-shaped parts, and ultimately the inability to stably prepare high-performance wear-resistant coatings in the existing titanium-aluminum alloy technology.

[0045] First, powder mixing is achieved through argon-protected planetary ball milling (e.g., ball-to-powder ratio 3:1 to 5:1, rotation speed 500-1000 r / min, water cooling rate 4-6℃ / min), keeping the powder in a loose state for easy subsequent sieving and feeding. Second, the powder hopper feeder is precisely matched with the parameters of the laser-directed energy deposition (LDED) equipment to achieve a stable molten pool, good interface bonding, no unmelted particles, and a dispersed distribution of the tungsten carbide reinforcing phase, enhancing bonding strength and hardness. Moreover, in LDED, a differentiated strategy of shaft-type rotary cladding / plate planar cladding is adopted for different component shapes, using an in-situ preheating control strategy to uniformly raise the temperature across the entire component surface. Large-sized components (cladding area > 50 cm²) are induction preheated to above the ductile-brittle transition temperature, fundamentally reducing thermal stress and suppressing cracks. Finally, residual stress is eliminated by immediate post-deposition stress-relief annealing (≥600℃ × ≥24h), followed by precise solution treatment and aging to fully dissolve the alloying elements and disperse the precipitating reinforcing phase. This innovative method achieves several synergistic effects: the combination of preheating and annealing completely solves the cracking problem, resulting in a coating with a hardness of 1300-1500 HV, a bonding strength of 80-90 MPa, and a wear rate as low as 3×10⁻⁶. -5 -8×10 -5 mm³ / (N·m).

[0046] Furthermore, S1. Titanium aluminum alloy powder and tungsten carbide powder are mixed by ball milling to obtain a mixed powder.

[0047] Specifically, the ball milling method uses an argon-protected planetary ball mill for powder mixing, and the amount of tungsten carbide powder used should not exceed 10% of the total volume of the mixed powder.

[0048] This step produces a composite powder with uniform composition and good dispersion. Compared to ordinary drum ball milling, planetary ball milling can achieve uniform mixing and mechanical alloying of powders with different particle sizes more quickly and thoroughly, ensuring that tungsten carbide powder is uniformly dispersed in titanium-aluminum alloy powder and avoiding uneven composition in subsequent coatings. Argon gas, as an inert protective atmosphere, isolates the powder from air, ensuring extremely low oxygen and nitrogen content after mixing. Tungsten carbide is a hard and brittle phase; excessive addition will significantly increase the brittleness of the coating, making it more prone to cracking under thermal stress. The amount of tungsten carbide powder used should not exceed 10% of the total volume of the mixed powder, striking a balance between improving hardness and ensuring the overall toughness of the coating.

[0049] The ball milling method in S1 uses yttrium oxide or zirconium oxide milling balls with a ball-to-material ratio of 3:1 to 5:1. Before ball milling, the material is purged with argon gas and the milling time is 12-24 hours. A water chiller is used for process cooling at a rate of 4-6°C / min. After ball milling, a vibrating screen is used to remove unbound fine powder.

[0050] Specifically, the ball-to-powder ratio is 3:1 to 5:1, with examples being 3:1, 4:1, and 5:1. A higher ball-to-powder ratio means more grinding balls and greater impact energy, ensuring mixing efficiency and mechanical alloying. If there are too few grinding balls (low ball-to-powder ratio) or too many grinding balls (high ball-to-powder ratio), the powder is prone to "cold welding" agglomeration on the grinding balls or tank walls, resulting in uneven powder mixing and directly causing a decrease in coating density and bonding strength. This ball-to-powder ratio range effectively prevents this phenomenon.

[0051] Pre-milling with argon gas washing can completely remove air: even if the grinding jar is sealed, air may still remain inside. "Gas washing and argon purging" (i.e., evacuating and then filling with argon gas, repeated several times) can minimize the residual oxygen content and provide protection for the powder.

[0052] The ball milling time (12~24h) is the time required to achieve uniform mixing and proper alloying: too short a time results in uneven mixing; too long a time leads to over-processing of the powder, causing severe deformation and oxidation. This time range is sufficient to achieve powder surface activation and good dispersion. Examples of ball milling times are 12h, 13h, 14h, 15h, 16h, 17h, 18h, 19h, 20h, 21h, 22h, 23h, and 24h.

[0053] The water chiller is turned on for process cooling at a rate of 4-6℃ / min. Controlling the cooling rate prevents the powder temperature inside the ball mill from becoming too high. Excessive powder temperature can soften the powder, causing it to agglomerate into large particles that "cold-weld" together. A moderate cooling rate avoids this phenomenon, keeping the powder loose and facilitating subsequent sieving and feeding. If the cooling rate is too high, it may lead to uneven temperature distribution within the ball mill jar, resulting in inconsistent powder processing due to localized temperature differences. It may also cause excessive load on the water chiller, increasing energy consumption. Conversely, if the cooling rate is too low, it may result in poor temperature control and further agglomeration of powder particles. Therefore, the water chiller cooling rate is 4-6℃ / min; for example, the chiller speeds are 4℃ / min, 5℃ / min, and 6℃ / min.

[0054] After ball milling, a vibrating sieve is used to remove unbonded fine powder, which determines the powder quality that will enter the next laser deposition process and contributes to the coating performance and process stability.

[0055] S2. When using the laser directional energy deposition equipment to apply the wear-resistant coating, the laser power is 500~800W, the laser spot diameter is 2~3mm, the laser moving speed is 10~30mm / s, the deposition layer thickness is 0.5~0.8mm, the powder hopper feeder speed is 50~100 r / min, and the argon gas delivery rate is 6~10L / min.

[0056] Specifically, a laser power of 500-800W, a laser spot diameter of 2-3mm, and a laser movement speed of 10-30mm / s are used to generate a suitable energy density, completely melting the surface of the titanium-aluminum alloy substrate to form a molten pool with good fluidity and wettability, ensuring metallurgical bonding while preventing excessive evaporation or molten pool splashing due to excessive energy. Using the laser as a heat source, the titanium-aluminum alloy substrate and wear-resistant alloy powder are simultaneously melted and deposited layer by layer. Specifically, controlling the parameters of the laser-directed energy deposition equipment ensures sufficient dissolution of alloying elements while avoiding element burn-off or coarse grains, resulting in moderate dissolution and uniform distribution of the tungsten carbide reinforcing phase. Simultaneously, the substrate undergoes micro-melting to form a metallurgical bond, providing a strengthening foundation for subsequent heat treatment, ultimately improving the hardness and bonding strength of the coating. Both laser power and laser movement speed jointly determine the linear energy density. Higher power and slower speed result in greater heat input; lower power and faster speed result in smaller heat input. The heat input should be just enough to cause micro-melting of the substrate surface (moderate dilution rate) while completely melting the powder to form a molten pool with good fluidity. The laser spot diameter affects the concentration of energy distribution. At the same linear energy density, a smaller spot results in more concentrated energy and a deeper molten pool; a larger spot results in more dispersed energy and a wider, shallower molten pool. The spot diameter ensures that the powder accurately falls into the molten pool and that the energy distribution is uniform. Heat input determines the molten pool temperature. Excessively high temperatures (>2870℃, where WC melts, partially dissolves) lead to excessive dissolution of WC, causing W and C elements to diffuse into the matrix and weaken the reinforcing phase; excessively low temperatures result in insufficient melting of WC, leading to poor bonding with the matrix. Considering the composition design of this invention, the parameters for laser-directed energy deposition in preparing the wear-resistant coating were synergistically designed. If the laser power is too high, the spot diameter is too large, or the laser moving speed is too fast, the heat input will be severely out of control, causing the molten pool to overheat, low-melting-point elements (such as Al) to burn off, the hardness of the substrate to decrease, and brittle intermetallic compounds may form at the interface, leading to a decrease in bonding strength. If the laser power is too low, the spot diameter is too small, or the laser moving speed is too slow, the energy will be insufficient, the substrate will not melt or will only partially melt, and the coating will merely "pile" on the surface. Subsequent heat treatment will have a poor strengthening effect, the substrate will have low hardness, and both hardness and bonding strength will be significantly reduced. For example, laser powers of 500W, 600W, 700W, and 800W, laser spot diameters of 2 and 3 mm, and laser moving speeds of 10 mm / s, 15 mm / s, 20 mm / s, 25 mm / s, and 30 mm / s can be used. The thickness can be controlled (0.5-0.8 mm): this thickness provides sufficient wear allowance; if it is too thin, it will not be wear-resistant, and if it is too thick, the internal stress accumulation will increase, making it prone to cracking. Examples include thicknesses of 0.5mm, 0.6mm, 0.7mm, and 0.8mm.

[0057] The powder feeder operates at a speed of 50-100 r / min, precisely matched to the parameters of the laser-directed energy deposition (LDED) equipment. This ensures that the amount of powder delivered to the molten pool per unit time is completely melted without "flooding" the pool, resulting in a stable molten pool, good interfacial bonding, no unmelted particles, and a dispersed distribution of the tungsten carbide reinforcing phase, enhancing bonding strength and hardness. Examples of powder feeder speeds are 50 r / min, 60 r / min, 70 r / min, 80 r / min, 90 r / min, and 100 r / min. Combined with argon gas delivery at 6-10 L / min, the argon gas acts as a carrier gas to deliver the powder into the molten pool and simultaneously forms an effective inert gas shield above the pool, preventing oxidation and nitriding of active elements such as titanium and aluminum at high temperatures, thus ensuring coating purity. If the argon gas delivery rate is too fast or too slow, the powder flow will be unstable, resulting in poor powder delivery accuracy. Examples of argon gas delivery rates are 6 L / min, 7 L / min, 8 L / min, 9 L / min, and 10 L / min.

[0058] Laser power, spot diameter, laser moving speed, powder hopper feeder speed, deposition layer thickness, and argon gas delivery rate collectively determine the temperature field, flow field, existence time, and solidification behavior of the molten pool, thereby directly controlling the coating's microstructure, reinforcing phase morphology, and interfacial bonding state, ultimately affecting the coating's hardness and bonding strength. Laser power and laser moving speed together determine the linear energy density.

[0059] When applying wear-resistant coatings to parts using the laser-directed energy deposition equipment, a rotary cladding method is used for shaft-type titanium-aluminum alloy parts, and a planar cladding method is used for plate-type titanium-aluminum alloy parts. An in-situ preheating control strategy is employed to ensure uniform temperature rise across the entire surface of the part. This is especially important when the part volume or cladding surface area is greater than 50 cm². 2 In addition, induction heating is required to raise the temperature of the titanium-aluminum alloy parts to above the ductile-brittle transition temperature.

[0060] This invention leverages the layer-by-layer deposition characteristics of laser-directed energy deposition, combined with customized processes for shafts (using a rotational cladding method) and plates (using a planar cladding method). By using rotational / planar cladding, it solves the shape adaptation problem, precisely matching the surface morphology of irregularly shaped parts. This achieves perfect coupling between laser energy, powder delivery, and part geometry, forming the technological foundation for obtaining high-quality conformal coatings. Specifically, when the part is a rotating body, it is mounted on the machine tool's rotating axis, and the print head is mounted on a robotic arm for conformal cladding. When the part is planar, the part itself is fixed, and the print head is mounted on a dual-axis motion stage for cladding. This enables the "conformal growth" coating preparation for shafts and plates, solving the core pain point of traditional methods being unable to adapt to complex parts. It boasts strong process adaptability and can be used for conformal coating of irregularly shaped parts.

[0061] Using an in-situ preheating control strategy, the temperature rises uniformly across the entire surface of the component, which is particularly beneficial for large-volume or large-cladding components with an area exceeding 50 cm². 2 When the surface area is too large, heat dissipation can cause the overall temperature to become unstable, easily leading to deformation and cracking. Induction preheating is employed, using induction heating to raise the component to above the ductile-brittle transition temperature. This increases the plasticity of the substrate, significantly reduces interfacial thermal stress, avoids microcracks, and significantly improves the plasticity / toughness of the coating, transitioning it from a "brittle state" to a "state with a certain degree of plasticity." The entire component becomes a "heat reservoir," greatly reducing the temperature difference between the molten pool and the substrate, thereby significantly reducing cracks caused by thermal stress at the source and solving the problems of uneven coating on complex-shaped components and thermal stress cracking in large-sized components.

[0062] S3. Immediately after deposition, remove the workpiece and place it in a muffle furnace for stress-relief annealing. The holding temperature should not be lower than 600℃ and the holding time should not be lower than 24h. After annealing, cool it with the furnace and remove it when the temperature is lower than 50℃.

[0063] The stress-relief annealing holding temperature should not be lower than 600℃ to reach the effective stress relaxation temperature. At this temperature and above, for titanium-aluminum alloys, the material can undergo microscopic plastic deformation through creep and dislocation reorganization, thereby effectively relaxing (eliminating) residual stress and preventing coating cracks. The holding time should not be less than 24 hours to ensure sufficient relaxation, providing ample time for atomic diffusion and dislocation movement, ensuring thorough stress elimination, not just on the surface. If the holding temperature is too low or the time is insufficient, it will lead to uneven stress elimination, and dangerous stress will still exist internally. After annealing, the workpiece should be cooled in the furnace. Removing it when the temperature is below 50℃ ensures that the workpiece has completely cooled to a stable state, minimizing the temperature gradient during the cooling process, and causing the various parts of the workpiece to shrink almost synchronously, thereby avoiding the introduction of new stress after the elimination of old stress and the generation of cracks.

[0064] S4. Solution treatment, solution temperature is 1300~1360℃, heat treatment time is 2~4h.

[0065] For titanium-aluminum alloys, a solution treatment temperature of 1300~1360℃ maximizes the dissolution of strengthening elements, forming a highly supersaturated solid solution. This is a prerequisite for the subsequent precipitation of fine, uniform strengthening phases through aging treatment. A holding time of 2~4 hours ensures compositional homogenization: providing sufficient time for long-range diffusion of alloying elements ensures the dissolution process is fully completed, resulting in a highly uniform coating composition and preventing microsegregation. If the solution treatment temperature is too low or the holding time is too short, the elements may not dissolve sufficiently. During subsequent aging, there will be insufficient strengthening elements available for precipitation, leading to uneven phase distribution and the coating's hardness and strength failing to meet design specifications, resulting in decreased wear resistance. If the solution treatment temperature is too high or the holding time is too long, the microstructure may coarsen, overheat, or even melt. For example, the solution treatment temperatures are 1300℃, 1310℃, 1320℃, 1330℃, 1340℃, 1350℃, and 1360℃, and the holding times are 2h, 2.5h, 3h, 3.5h, and 4h, respectively.

[0066] S4. The aging treatment temperature is 840-860℃, and the holding time is 6-8h.

[0067] An aging treatment temperature of 840-860℃ and a holding time of 6-8 hours are beneficial for the precipitation of fine, dispersed strengthening phases that are crucial for performance, while avoiding the formation of brittle phases that can severely impair toughness. If the aging temperature is too high or the time is too long, the precipitated phases may coarsen, resulting in uneven and lower performance. Conversely, if the aging temperature is too low or the time is too short, the coating's hardness and strength may not reach their peak values, also resulting in uneven and lower performance. For example, aging treatment temperatures of 840℃, 845℃, 850℃, 855℃, and 860℃, with holding times of 6 hours, 6.5 hours, 7 hours, 7.5 hours, and 8 hours, respectively, are used.

[0068] The wear-resistant coating obtained by this invention has a hardness of 1300HV-1500HV, a bonding strength of 85 MPa-90 MPa, and a wear rate of 3×10⁻⁶. -5 -8×10 -5 mm³ / (N·m), and the coefficient of friction is 0.36-0.52.

[0069] This invention first employs a multi-element alloying design to introduce tungsten carbide powder while maintaining the lightweight and heat-resistant advantages of the titanium-aluminum matrix. Secondly, it ensures uniform dispersion of the components by pre-mixing the titanium-aluminum alloy powder and tungsten carbide powder through argon-protected ball milling. Then, it utilizes laser-directed energy deposition technology to simultaneously melt and layer-by-layer deposit the titanium-aluminum alloy substrate and wear-resistant alloy powder using a laser, coupled with in-situ preheating control. After deposition, stress-relief annealing, solution treatment, and aging treatment achieve metallurgical-grade bonding between the coating and the substrate. The final wear-resistant coating exhibits high hardness (1300-1500 HV), bonding strength (85-90 MPa), and wear resistance (wear rate) (3×10⁻⁶). -5 -8×10-5 With a coefficient of friction of 0.36-0.52 mm³ / (N·m) and high hardness, strong bonding, and low wear energy, it significantly improves the service life of titanium-aluminum alloys in high-temperature wear scenarios. It solves the problems of existing technologies, such as coating cracking in large-size parts, low bonding strength between coating and substrate, high wear rate, difficulty in adapting to complex-shaped parts, and ultimately the inability to stably prepare high-performance wear-resistant coatings.

[0070] To more clearly describe the present invention, the following embodiments and comparative examples are provided for further illustration.

[0071] Example 1 This example provides a wear-resistant coating for tungsten carbide-reinforced titanium-aluminum alloy parts manufactured by additive manufacturing and a preparation method thereof. The coating is deposited on engine valve parts, which are shaft-type titanium-aluminum alloy parts.

[0072] The chemical composition of the additively manufactured tungsten carbide reinforced titanium-aluminum alloy wear-resistant coating, designed using TNM titanium-aluminum alloy powder and tungsten carbide powder, is as follows (atomic percentage): W 2at%, C 2at%, Al 44at%, Nb 4at%, Ta 1at%, Mo 0.5at%, B 0.5at%, oxygen content less than 600ppm, with the balance being Ti and unavoidable impurity elements.

[0073] The titanium-aluminum alloy powder had an average particle size of 100 μm, and the tungsten carbide powder had an average particle size of 25 μm. Both powders were prepared using the EIGA method.

[0074] The composition of TNM titanium-aluminum alloy powder is Ti-44.5Al-4Nb-0.5Mo-0.2B, and the composition of tungsten carbide powder is 100% WC.

[0075] The steps of depositing the above-mentioned wear-resistant coating on engine valve parts include: S1. Use an argon-protected planetary ball mill to mix TNM titanium-aluminum alloy powder and tungsten carbide powder, with tungsten carbide powder accounting for 3% of the total volume of the mixed powder.

[0076] Yttrium oxide or zirconium oxide grinding balls were used at a ball-to-material ratio of 3.5:1. Before ball milling, the mixture was purged three times and then purged with argon. The milling time was 12 hours, with a water chiller used for process cooling at a speed of 600 rpm. After milling, unbound fine powder was removed using a vibrating screen.

[0077] S2. A wear-resistant coating was deposited using a laser-guided energy deposition (LAD) system with a laser power of 550W, a laser spot diameter of 2.2mm, a laser moving speed of 15mm / s, a deposition layer thickness of 0.65mm, a powder hopper feeder speed of 70 r / min, and an argon gas delivery rate of 4.5L / min.

[0078] The coating is deposited on engine valve parts, which are shaft-type titanium-aluminum alloy components. A rotary cladding method is used to fix the parts on a machine tool chuck, and a multi-degree-of-freedom robotic arm drives the print head to perform conformal cladding. The cladding surface area is greater than 50 cm². 2 Induction heating is used to raise the temperature of titanium-aluminum alloy parts to over 750°C.

[0079] S3. Immediately after deposition, the workpiece is removed and placed in a muffle furnace for stress-relief annealing at a holding temperature of 650℃ for 36 hours. After annealing, the workpiece is cooled in the furnace and removed when the temperature is below 50℃.

[0080] S4. After annealing, perform solution aging treatment at a temperature of 1300℃ for 2 hours and an aging temperature of 850℃ for 6 hours.

[0081] Example 2 This example provides a wear-resistant coating for tungsten carbide-reinforced titanium-aluminum alloy parts manufactured by additive manufacturing and a method for its preparation. The coating is deposited on turbine blade parts of an aero-engine, and the blade parts are shaft-type titanium-aluminum alloy parts.

[0082] Using 458 titanium-aluminum alloy powder (chemical composition Ti-45Al-8Nb) and tungsten carbide powder, the chemical composition of the additively manufactured tungsten carbide-reinforced titanium-aluminum alloy wear-resistant coating, by atomic percentage, is: W 4at%, C 4at%, Al 45at%, Nb 8at%, Ta 2at%, Mo 0.6at%, B 0.25at%, oxygen content less than 600ppm, with the balance being Ti and unavoidable impurity elements.

[0083] The titanium-aluminum alloy powder with an average particle size of 90 μm and the tungsten carbide powder with an average particle size of 30 μm were used, and both powders were prepared using the PREP method.

[0084] The composition of 458 titanium-aluminum alloy powder is Ti-45Al-8Nb, and the composition of tungsten carbide powder is 100% WC.

[0085] The steps for depositing the above-mentioned wear-resistant coating on turbine blade components include: S1. Use an argon-protected planetary ball mill to mix 458 titanium aluminum alloy powder and tungsten carbide powder, with tungsten carbide powder accounting for 5% of the total volume of the mixed powder.

[0086] Yttrium oxide or zirconium oxide grinding balls were used at a ball-to-material ratio of 5:1. Before ball milling, the mixture was purged three times and then purged with argon. The milling time was 18 hours, with a water chiller used for process cooling at a speed of 700 rpm. After milling, a vibrating screen was used to remove unbound fine powder.

[0087] S2. A wear-resistant coating was prepared by laser directional energy deposition equipment with a laser power of 600W, a laser spot diameter of 2.4mm, a laser moving speed of 21mm / s, a deposition layer thickness of 0.7mm, a powder hopper feeder speed of 70 r / min, and an argon gas delivery rate of 8L / min.

[0088] The coating is deposited on turbine blade parts of aero-engines. These turbine blade parts are shaft-type titanium-aluminum alloy components. A rotary cladding method is used, in which the blade parts are fixed on a machine tool spindle chuck, and a multi-degree-of-freedom robotic arm drives the print head to perform conformal cladding. The cladding surface area is greater than 50 cm². 2 Induction heating is used to raise the temperature of titanium-aluminum alloy parts to over 800°C.

[0089] S3. Immediately after deposition, the workpiece is removed and placed in a muffle furnace for stress-relief annealing at a holding temperature of 700℃ for 48 hours. After annealing, the workpiece is cooled in the furnace and removed when the temperature is below 50℃.

[0090] S4. After annealing, perform solution aging treatment at a temperature of 1330℃ for 3 hours and an aging temperature of 900℃ for 7 hours.

[0091] Example 3 This example provides a wear-resistant coating for tungsten carbide-reinforced titanium-aluminum alloy parts manufactured by additive manufacturing and a preparation method thereof. The coating is deposited on thin-walled plate parts, and the blade parts are flat titanium-aluminum alloy parts.

[0092] Using 47XD titanium-aluminum alloy powder and tungsten carbide powder, the chemical composition of the additively manufactured tungsten carbide-reinforced titanium-aluminum alloy wear-resistant coating, by atomic percentage, is: W 5at%, C 5at%, Al 40at%, Nb 8.8at%, Ta 4at%, Mo 0.75at%, B 0.75at%, oxygen content less than 600ppm, with the balance being Ti and unavoidable impurity elements.

[0093] The titanium-aluminum alloy powder with an average particle size of 130 μm and the tungsten carbide powder with an average particle size of 20 μm were used, and both powders were prepared using the PREP method.

[0094] The composition of 47XD titanium-aluminum alloy powder is Ti-47Al-2Nb-2Mn-0.8 vol.% TiB2, and the composition of tungsten carbide powder is 100% WC.

[0095] The steps for depositing the above-mentioned wear-resistant coating on thin-walled plate parts include: S1. Use an argon-protected planetary ball mill to mix 47XD titanium-aluminum alloy powder and tungsten carbide powder, with tungsten carbide powder accounting for 6% of the total volume of the mixed powder.

[0096] Yttrium oxide or zirconium oxide grinding balls were used at a ball-to-material ratio of 5:1. Before ball milling, the mixture was purged three times and then purged with argon. The milling time was 20 hours, with a water chiller used for process cooling at a speed of 800 rpm. After milling, a vibrating screen was used to remove unbound fine powder.

[0097] S2. A wear-resistant coating was prepared by laser directional energy deposition equipment with a laser power of 700W, a laser spot diameter of 2.5mm, a laser moving speed of 25mm / s, a deposition layer thickness of 0.6mm, a powder hopper feeder speed of 80 r / min, and an argon gas delivery rate of 8.5L / min.

[0098] The coating is deposited on a thin-walled plate part, which is a shaft-type titanium-aluminum alloy component. A flat plate cladding method is used, where the thin-walled plate part is fixed to the chassis of the cladding equipment. A dual-axis motion mechanism drives the print head to perform the cladding. The cladding surface area is greater than 50 cm². 2 Induction heating is used to heat titanium-aluminum alloy parts to over 900°C.

[0099] S3. Immediately after deposition, the workpiece is removed and placed in a muffle furnace for stress-relief annealing. The holding temperature is 800℃ and the holding time is 40h. After annealing, the workpiece is cooled in the furnace and removed when the temperature is below 50℃.

[0100] S4. After annealing, perform solution aging treatment at a temperature of 1360℃ for 4 hours, followed by aging at 860℃ for 8 hours.

[0101] Example 4 This example provides a wear-resistant coating for tungsten carbide-reinforced titanium-aluminum alloy parts manufactured by additive manufacturing and a preparation method thereof. The coating is deposited on a hydrocyclone part, which is a shaft-type titanium-aluminum alloy part.

[0102] Using 5010 titanium-aluminum alloy powder and tungsten carbide powder, the chemical composition of the additively manufactured tungsten carbide-reinforced titanium-aluminum alloy wear-resistant coating, by atomic percentage, is: W 5.5at%, C 5.5at%, Al 42at%, Nb 8.8at%, Ta 3at%, Mo 0.35at%, B 0.65at%, oxygen content less than 600ppm, with the balance being Ti and unavoidable impurity elements.

[0103] The titanium-aluminum alloy powder had an average particle size of 100 μm, and the tungsten carbide powder had an average particle size of 30 μm. Both powders were prepared using the EIGA method.

[0104] The composition of 5010 titanium-aluminum alloy powder is Ti-50Al-10Nb, and the composition of tungsten carbide powder is 100% WC.

[0105] The step of depositing the above-mentioned wear-resistant coating on the hydrocyclone parts includes: S1. Use an argon-protected planetary ball mill to mix 5010 titanium-aluminum alloy powder and tungsten carbide powder. After mixing with tungsten carbide powder, the powder accounts for 8% of the total volume.

[0106] Yttrium oxide or zirconium oxide grinding balls were used at a ball-to-material ratio of 4:1. Before ball milling, the mixture was purged three times and then purged with argon. The milling time was 24 hours, with a water chiller used for process cooling at a speed of 500 rpm. After milling, a vibrating screen was used to remove unbound fine powder.

[0107] S2. A wear-resistant coating was prepared by laser directional energy deposition equipment with a laser power of 500W, a laser spot diameter of 2mm, a laser moving speed of 10mm / s, a deposition layer thickness of 0.5mm, a powder hopper feeder speed of 50 r / min, and an argon gas delivery rate of 6L / min.

[0108] The coating is deposited on the hydrocyclone parts, which are shaft-type titanium-aluminum alloy components. A rotary cladding method is used, fixing the parts on a machine tool spindle chuck. A multi-degree-of-freedom robotic arm drives the print head to perform conformal cladding, with a cladding surface area greater than 50 cm². 2 Induction heating is used to heat titanium-aluminum alloy parts to over 900°C.

[0109] S3. Immediately after deposition, the workpiece is removed and placed in a muffle furnace for stress-relief annealing. The holding temperature is 800℃ and the holding time is 40h. After annealing, the workpiece is cooled in the furnace and removed when the temperature is below 50℃.

[0110] S4. After annealing, perform solution aging treatment at a temperature of 1360℃ for 3 hours and an aging temperature of 850℃ for 6 hours.

[0111] Example 5 This example provides a wear-resistant coating for tungsten carbide-reinforced titanium-aluminum alloy parts manufactured by additive manufacturing and a preparation method thereof. The coating is deposited on a turbocharger part of an automobile engine, which is a shaft-type titanium-aluminum alloy part.

[0112] Using 4822 titanium-aluminum alloy powder and tungsten carbide powder, the chemical composition of the additively manufactured tungsten carbide-reinforced titanium-aluminum alloy wear-resistant coating, by atomic percentage, is: W 5at%, C 5at%, Al 50at%, Nb 8.8at%, Ta 4at%, Mo 0.75at%, B 0.75at%, oxygen content less than 600ppm, with the balance being Ti and unavoidable impurity elements.

[0113] The titanium-aluminum alloy powder with an average particle size of 130 μm and the tungsten carbide powder with an average particle size of 20 μm were used, and both powders were prepared using the EIGA method.

[0114] The composition of 4822 titanium-aluminum alloy powder is Ti-48Al-2Cr-2Nb, and the composition of tungsten carbide powder is 100% WC.

[0115] The steps for depositing the above-mentioned wear-resistant coating on turbocharger components of an automotive engine include: S1. Use an argon-protected planetary ball mill to mix 4822 titanium-aluminum alloy powder and tungsten carbide powder, with tungsten carbide powder accounting for 10% of the total volume of the mixed powder.

[0116] Yttrium oxide or zirconium oxide grinding balls were used at a ball-to-material ratio of 5:1. Before ball milling, the mixture was purged three times and then purged with argon. The milling time was 23 hours, with a water chiller used for process cooling at a speed of 1000 rpm. After milling, a vibrating screen was used to remove unbound fine powder.

[0117] S2. A wear-resistant coating was prepared by laser directional energy deposition equipment with a laser power of 800W, a laser spot diameter of 3mm, a laser moving speed of 30mm / s, a deposition layer thickness of 0.8mm, a powder hopper feeder speed of 100 r / min, and an argon gas delivery rate of 9.5L / min.

[0118] The coating is deposited on a turbocharger turbine component of an automotive engine. This component is a shaft-type titanium-aluminum alloy part. A rotary cladding method is used, where the part is fixed to a machine tool chuck, and a multi-degree-of-freedom robotic arm drives the print head to perform conformal cladding. The cladding area is greater than 50 cm². 2 Induction heating is used to heat titanium-aluminum alloy parts to over 900°C.

[0119] S3. Immediately after deposition, the workpiece is removed and placed in a muffle furnace for stress-relief annealing. The holding temperature is 800℃ and the holding time is 40h. After annealing, the workpiece is cooled in the furnace and removed when the temperature is below 50℃.

[0120] S4. After annealing, perform solution aging treatment at a temperature of 1350℃ for 3 hours and an aging temperature of 845℃ for 6.5 hours.

[0121] Comparative Example 1 This comparative example provides a wear-resistant coating for tungsten carbide-reinforced titanium-aluminum alloy parts manufactured by additive manufacturing and a preparation method thereof. The coating is deposited on engine valve parts, which are shaft-type titanium-aluminum alloy parts.

[0122] The chemical composition of the additively manufactured tungsten carbide reinforced titanium-aluminum alloy wear-resistant coating, designed using TNM titanium-aluminum alloy powder and tungsten carbide powder, is as follows (atomic percentage): W 12at%, C 2at%, Al 44at%, Nb 4at%, Ta 1at%, Mo 0.5at%, B 0.5at%, oxygen content less than 600ppm, with the balance being Ti and unavoidable impurity elements.

[0123] The titanium-aluminum alloy powder had an average particle size of 180 μm, and the tungsten carbide powder had an average particle size of 65 μm. Both powders were prepared using the EIGA method.

[0124] The rest is the same as in Example 1.

[0125] Comparative Example 2 This comparative example provides a wear-resistant coating for tungsten carbide-reinforced titanium-aluminum alloy parts manufactured by additive manufacturing and a preparation method thereof. The coating is deposited on engine valve parts, which are shaft-type titanium-aluminum alloy parts.

[0126] The chemical composition of the additive manufacturing tungsten carbide reinforced titanium-aluminum alloy wear-resistant coating, designed using TNM titanium-aluminum alloy powder and tungsten carbide powder, is as follows (atomic percentage): W 2at%, C 2at%, Al 50at%, Nb 4at%, Ta 1at%, Mo 0.5at%, B 0.5at%, oxygen content less than 600ppm, with the balance being Ti and unavoidable impurity elements.

[0127] The titanium-aluminum alloy powder had an average particle size of 180 μm, and the tungsten carbide powder had an average particle size of 65 μm. Both powders were prepared using the EIGA method.

[0128] The rest is the same as in Example 1.

[0129] Comparative Example 3 This comparative example provides a wear-resistant coating for tungsten carbide-reinforced titanium-aluminum alloy parts manufactured by additive manufacturing and a preparation method thereof. The coating is deposited on engine valve parts, which are shaft-type titanium-aluminum alloy parts.

[0130] The chemical composition of the additively manufactured tungsten carbide reinforced titanium-aluminum alloy wear-resistant coating, designed using TNM titanium-aluminum alloy powder and tungsten carbide powder, is as follows (atomic percentage): W 2at%, C 2at%, Al 44at%, Nb 3at%, Ta 1at%, Mo 0.5at%, B 0.5at%, oxygen content less than 600ppm, with the balance being Ti and unavoidable impurity elements.

[0131] The titanium-aluminum alloy powder had an average particle size of 180 μm, and the tungsten carbide powder had an average particle size of 65 μm. Both powders were prepared using the EIGA method.

[0132] The rest is the same as in Example 1.

[0133] Comparative Example 4 This comparative example provides a wear-resistant coating for tungsten carbide-reinforced titanium-aluminum alloy parts manufactured by additive manufacturing and a preparation method thereof. The coating is deposited on engine valve parts, which are shaft-type titanium-aluminum alloy parts.

[0134] S1. The ball milling method uses an argon-protected planetary ball mill for powder mixing, and the tungsten carbide powder used accounts for 12% of the total volume of the mixed powder.

[0135] Yttrium oxide or zirconium oxide grinding balls were used at a ball-to-material ratio of 5.5:1. Before ball milling, the mixture was purged three times and then purged with argon. The milling time was 24 hours, with a water chiller used for process cooling at a speed of 1600 r / min. After milling, unbound fine powder was removed using a vibrating screen.

[0136] The rest is the same as in Example 1.

[0137] Comparative Example 5 This comparative example provides a wear-resistant coating for tungsten carbide-reinforced titanium-aluminum alloy parts manufactured by additive manufacturing and a preparation method thereof. The coating is deposited on engine valve parts, which are shaft-type titanium-aluminum alloy parts.

[0138] S2. A wear-resistant coating was deposited using a laser-guided energy deposition (LAD) system with a laser power of 1500W, a laser spot diameter of 12mm, a laser moving speed of 25mm / s, a deposition layer thickness of 2.6mm, a powder hopper feeder speed of 6 r / min, and an argon gas delivery rate of 7.5L / min.

[0139] The coating is deposited on the engine valve parts, which are shaft-type titanium-aluminum alloy components. The coating is applied using a rotary cladding method, and induction heating is used to raise the temperature of the titanium-aluminum alloy components to above 650°C.

[0140] Comparative Example 6 S3. Immediately after deposition, the workpiece is removed and placed in a muffle furnace for stress-relief annealing at a holding temperature of 450°C for 36 hours. After annealing, the workpiece is cooled in the furnace and removed when the temperature is below 50°C.

[0141] The rest is the same as in Example 1.

[0142] Comparative Example 7 S4. After annealing, perform solution treatment and aging treatment. The solution treatment temperature is 1100℃ and the holding time is 2h. The aging temperature is 650℃ and the holding time is 6h.

[0143] The rest is the same as in Example 1.

[0144] Performance testing Specifically, the performance of Examples 1-3 and Comparative Examples 1-5 provided by this invention is shown in Table 1. Hardness refers to standard GB / T 4340.1, bonding strength refers to standard GB / T 8642, and wear rate / friction coefficient refers to standard GB / T 8642.

[0145] Table 1 Performance of Examples 1-3 and Comparative Examples 1-5

[0146] As can be seen from Table 1, the additive manufacturing tungsten carbide reinforced titanium-aluminum alloy wear-resistant coatings (Examples 1-5) provided by this invention exhibit excellent performance in terms of hardness, bonding strength, and wear resistance (wear rate). Specifically, the hardness (1300HV-1500HV), bonding strength (85 MPa-90MPa), and wear resistance (wear rate) (3×10) are all superior. -5 -8×10 -5 mm³ / (N·m) and coefficient of friction (0.36-0.52). Moreover... Figure 2 It can be seen that the coating structure of the present invention has a dispersed distribution of reinforcing phase, good interfacial bonding, and a dense, defect-free coating. The coating cross-section SEM (Series Imaging Study) shows... Figure 3 No microcracks were observed. In contrast, the performance of Comparative Examples 1-7 was significantly inferior to that of Examples 1-5, which fully demonstrates the necessity and superiority of the chemical composition, powder specifications, and overall process parameters defined in this invention as a holistic technical solution.

[0147] Specifically, the W, Al, and Nb content in Comparative Examples 1-3 exceeded the scope of this invention, resulting in decreased hardness and bonding strength, and increased wear rate. Comparative Example 4 used an excessively high ball-to-material ratio and rotation speed in the ball milling process, causing uneven powder mixing and directly leading to a decrease in coating bonding strength. Comparative Example 5 used excessively high laser power and an excessively large spot diameter, causing overburning of the molten pool and a significant reduction in hardness and bonding strength. The stress-relief annealing temperature of Comparative Example 6 was lower than the lower limit of this invention (450°C), which could not effectively eliminate the huge residual stress generated during the deposition process, resulting in stress concentration in the coating, poor bonding strength (only 53 MPa), and high wear rate. The solution aging temperatures of Comparative Example 7 were all too low, resulting in insufficient solution and coarse precipitates, failing to exert the precipitation strengthening effect, leading to insufficient hardness and poor wear resistance.

[0148] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A wear-resistant coating for additively manufactured tungsten carbide-reinforced titanium-aluminum alloy, characterized in that, The chemical composition, by atomic percentage, is: W 0.5-10at%, C 0.5-10at%, Al 40-46at%, Nb 4-10at%, Ta 1-4at%, Mo 0.1-0.9at%, B 0.25-0.75at%, oxygen content less than 600ppm, with the balance being Ti and unavoidable impurity elements.

2. The additive manufacturing tungsten carbide reinforced titanium-aluminum alloy wear-resistant coating according to claim 1, characterized in that, The wear-resistant coating contains an in-situ generated WC reinforcing phase.

3. The additive manufacturing tungsten carbide reinforced titanium-aluminum alloy wear-resistant coating according to claim 1, characterized in that, The wear-resistant coating is prepared by additive manufacturing using powder, which includes titanium-aluminum alloy powder and tungsten carbide powder. The titanium-aluminum alloy powder has a particle size of 50~150μm, and the tungsten carbide powder has a particle size of 15~40μm.

4. A method for preparing an additively manufactured tungsten carbide reinforced titanium-aluminum alloy wear-resistant coating as described in any one of claims 1-3, characterized in that, The preparation method includes the following steps: S1. Titanium aluminum alloy powder and tungsten carbide powder are mixed by ball milling to obtain a mixed powder; S2. The mixed powder is deposited onto the surface of the titanium-aluminum alloy component using a laser-directed energy deposition (LDED) device; S3. Perform stress-relief annealing on the deposited component; S4. After annealing, perform solution treatment and aging treatment.

5. The preparation method according to claim 4, characterized in that, In S1, the ball milling method uses an argon-protected planetary ball mill for powder mixing, and the tungsten carbide powder should not exceed 10% of the total volume of the powder after mixing.

6. The preparation method according to claim 4, characterized in that, In S1, the ball milling method uses yttrium oxide or zirconium oxide milling balls with a ball-to-material ratio of 3:1 to 5:

1. Before ball milling, the ball milling process is performed by gas washing and argon purging. The ball milling time is 12 to 24 hours, and a water chiller is turned on for process cooling. The cooling rate of the water chiller is 4-6℃ / min.

7. The preparation method according to claim 4, characterized in that, In S2, when the laser-directed energy deposition equipment is used to prepare the wear-resistant coating, the laser power is 500~800W, the laser spot diameter is 2~3mm, the laser moving speed is 10~30mm / s, the deposition layer thickness is 0.5~0.8mm, the powder hopper feeder speed is 50~100 r / min, and the argon gas delivery rate is 6~10L / min.

8. The preparation method according to claim 4, characterized in that, In S2, when using the laser-directed energy deposition equipment to deposit a wear-resistant coating on parts, a rotary cladding method is used for shaft-type titanium-aluminum alloy parts, and a planar cladding method is used for plate-type titanium-aluminum alloy parts; an in-situ preheating control strategy is used to ensure a uniform temperature increase across the entire surface of the part, when the part volume or the area of ​​the cladding surface is greater than 50 cm². 2 In addition, induction heating is required to raise the temperature of the titanium-aluminum alloy parts to above the ductile-brittle transition temperature.

9. The preparation method according to claim 4, characterized in that, In S3, the workpiece is immediately removed after deposition and placed in a muffle furnace for stress-relief annealing. The holding temperature is not lower than 600℃ and the holding time is not lower than 24h. After annealing, the workpiece is cooled in the furnace and removed when the temperature is lower than 50℃.

10. The preparation method according to claim 4, characterized in that, In S4, the solution treatment temperature is 1300~1360℃, and the holding time is 2~4h; the aging treatment temperature is 840-860℃, and the holding time is 6~8h.

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