High-strength and high-toughness titanium-aluminum coating as well as preparation method and application thereof

Abstract

The invention provides a high-strength and high-toughness titanium-aluminum coating and a preparation method and application thereof.The preparation method comprises the following steps that A, first mixed powder and second mixed powder are laid on the surface of a titanium alloy component layer by layer, and a prefabricated titanium-aluminum coating is obtained; the first mixed powder comprises Ti powder and TC4 powder; the second mixed powder comprises Al powder and TC4 powder; and (B) pulse current treatment is conducted on the prefabricated titanium-aluminum coating, and the high-strength and high-toughness titanium-aluminum coating is obtained. According to the method, gradient thermal expansion coefficient matching and interface stress reduction are achieved by arranging the multiple TC4 alloy transition layers, pulse instantaneous energy of pulse current treatment can enable local micro-areas of the coating to be remelted, grain growth is restrained, submicron-order equiaxed crystals are obtained, dislocation slippage is induced by electromagnetic force, residual stress is released, and the thermal expansion coefficient of the coating is reduced. And in addition, the in-situ exothermic reaction promotes mutual diffusion of elements, a metallurgical bonding interface is formed, and the strength and toughness of the coating are improved.

Description

Technical Field

[0001] This invention belongs to the field of titanium alloy surface treatment technology, and particularly relates to a high-strength and high-toughness titanium-aluminum coating, its preparation method and application. Background Technology

[0002] Shaft components are an indispensable key component in helicopter transmission systems, and their comprehensive performance is directly related to the flight safety of helicopters. With the improvement of helicopter performance, the structure of shaft components used in transmission systems has become more complex, the size has increased, and the weight has increased as well. In order to meet the requirements of weight reduction, the proportion of titanium alloy in the selection of shaft components for helicopter transmission systems is gradually increasing, so as to reduce the weight of the whole aircraft. With the application of titanium alloy shaft components, compared with traditional steel materials, the problem of surface wear resistance has become more and more serious.

[0003] Meanwhile, due to the long-term operation of components in high-temperature oxidizing environments, high-performance thermal protective coatings are urgently needed. While traditional titanium-aluminum (TiAl) coatings possess low density and good high-temperature oxidation resistance, their inherent high room-temperature brittleness and poor thermal fatigue performance easily lead to coating peeling and failure, severely limiting component lifespan. Although Russian-developed TiAl coating technologies for shaft components (such as multilayer vapor deposition processes) have improved oxidation resistance, they still suffer from limited toughness improvement and complex, expensive processes. With the phasing out of this technology, there is an urgent need to develop an alternative that significantly improves the coating's strength, toughness, and service reliability while ensuring excellent oxidation resistance. Summary of the Invention

[0004] The purpose of this invention is to provide a high-strength and high-toughness titanium-aluminum coating, its preparation method and application. The titanium-aluminum coating prepared by the method of this invention has excellent oxidation resistance while achieving a synergistic improvement in strength and toughness.

[0005] This invention provides a method for preparing a high-strength, high-toughness titanium-aluminum coating, comprising the following steps:

[0006] A) A first mixed powder and a second mixed powder are laid layer by layer on the surface of a titanium alloy component to obtain a pre-made titanium-aluminum coating;

[0007] The first mixed powder comprises Ti powder and TC4 powder; the second mixed powder comprises Al powder and TC4 powder.

[0008] B) The pre-fabricated titanium-aluminum coating is subjected to pulsed current treatment to obtain a high-strength and high-toughness titanium-aluminum coating.

[0009] The current density of the pulse current processing is 5 × 10³ A / cm² 2 ~1×10 5 A / cm 2 The single-pulse energy is 5 J / cm². 2~50 J / cm 2 .

[0010] Preferably, the titanium alloy component is a TC4 titanium alloy component.

[0011] Preferably, in the first mixed powder, the mass ratio of Ti powder to TC4 powder is (0.8~2.0):1.

[0012] Preferably, in the second mixed powder, the mass ratio of Al powder to TC4 powder is (0.8~2.0):1.

[0013] Preferably, the first mixed powder and the second mixed powder are laid layer by layer on the surface of the titanium alloy component by cold isostatic pressing.

[0014] Preferably, the pulse frequency of the pulse current processing is 50Hz~500Hz, and the single pulse width is 10~400.

[0015] Preferably, the processing time of the pulse current processing is 30s to 180s, and the number of pulses is 1 to 10.

[0016] Preferably, during the pulsed current treatment process, when the coating temperature reaches 1200~1250℃, the treated area is rapidly cooled by air until it is cooled to room temperature.

[0017] This invention provides a high-strength and high-toughness titanium-aluminum coating, which is prepared according to the preparation method described above, and the thickness of the high-strength and high-toughness titanium-aluminum coating is 5~10mm.

[0018] This invention provides the application of the high-strength and high-toughness titanium-aluminum coating as described above in titanium alloy shaft components.

[0019] This invention provides a method for preparing a high-strength, high-toughness titanium-aluminum coating, comprising the following steps: A) layering a first mixed powder and a second mixed powder on the surface of a titanium alloy component to obtain a pre-formed titanium-aluminum coating; the first mixed powder comprises Ti powder and TC4 powder; the second mixed powder comprises Al powder and TC4 powder; B) subjecting the pre-formed titanium-aluminum coating to pulsed current treatment to obtain a high-strength, high-toughness titanium-aluminum coating; the current density of the pulsed current treatment is 5 × 10³ A / cm². 2 ~1×10 5 A / cm 2 The single-pulse energy is 5 J / cm². 2 ~50 J / cm 2This invention achieves gradient thermal expansion coefficient matching by setting multiple TC4 alloy transition layers, reducing interfacial stress. The pulsed instantaneous energy of pulsed current treatment enables local micro-area remelting of the coating and inhibits grain growth, obtaining submicron-level equiaxed crystals. Electromagnetic force induces dislocation slip to release residual stress, and the in-situ exothermic reaction promotes element interdiffusion, forming a metallurgical bonding interface, improving the strength and toughness of the coating. Experimental results show that the titanium-aluminum coating prepared by the method of this invention has a hardness of 850~1100HV0.3, fracture toughness KIC≥25 MPa·m¹ / ², and coating bonding strength≥150 MPa, which is about 30% higher than that of the traditional process. The oxidation weight gain at 1100℃ is <1.0 (mg / cm²·100h), and the coating porosity is reduced to ≤0.5% (traditional process ≥2%). The cycle life (1100℃↔ room temperature) is >500 times (traditional <200 times). Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0021] Figure 1 This is the pulse current processing device used in the present invention.

[0022] 1-Base, 2-Bracket, 3-Titanium alloy shaft, 4-Reinforcing layer, 5-Pulse power supply, 6-Jet nozzle. Detailed Implementation

[0023] This invention provides a method for preparing a high-strength, high-toughness titanium-aluminum coating, comprising the following steps:

[0024] A) A first mixed powder and a second mixed powder are laid layer by layer on the surface of a titanium alloy component to obtain a pre-made titanium-aluminum coating;

[0025] The first mixed powder comprises Ti powder and TC4 powder; the second mixed powder comprises Al powder and TC4 powder.

[0026] B) The pre-fabricated titanium-aluminum coating is subjected to pulsed current treatment to obtain a high-strength and high-toughness titanium-aluminum coating.

[0027] The current density of the pulse current processing is 5 × 10³ A / cm² 2 ~1×10 5 A / cm 2 The single-pulse energy is 5 J / cm². 2 ~50 J / cm 2 .

[0028] In this invention, the titanium alloy component is preferably a TC4 titanium alloy component. Specifically, in some embodiments of this invention, it can be a TC4 titanium alloy shaft component, such as a TC4 titanium alloy pipe.

[0029] The present invention preferably mixes Ti powder and TC4 powder to obtain a first mixed powder, and mixes Al powder and TC4 powder to obtain a second mixed powder.

[0030] In this invention, the D90 of the Ti powder is ≤20μm, and the particle size of the TC4 powder is preferably 45~106μm; in the first mixed powder, the mass ratio of Ti powder to TC4 powder is preferably (0.8~2.0):1, more preferably (1.0~1.8):1, such as 0.8:1, 0.9:1, 1.0:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2.0:1, preferably a range of values ​​with any of the above values ​​as the upper or lower limit.

[0031] In this invention, the D90 of the Al powder is ≤25μm, and the particle size of the TC4 powder is preferably 45~106μm; in the second mixed powder, the mass ratio of Al powder to TC4 powder is preferably (0.8~2.0):1, more preferably (1.0~1.8):1, such as 0.8:1, 0.9:1, 1.0:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2.0:1, preferably a range of values ​​with any of the above values ​​as the upper or lower limit.

[0032] The present invention preferably employs a cold isostatic pressing method, in which the first mixed powder and the second mixed powder are sequentially laid layer by layer on the surface of the titanium alloy component. First, a layer of the first mixed powder is laid, followed by cold isostatic pressing, then a layer of the second mixed powder is laid, followed by cold isostatic pressing, and so on, until the coating thickness reaches the required level.

[0033] In this invention, the pressure of cold isostatic pressing of the first mixed powder is preferably 200~250MPa, more preferably 220~240MPa. Under this higher pressure, the Ti powder with high hardness and poor plasticity can be deformed. The holding time is preferably 10~15min, more preferably 12~14min. This longer holding time can ensure that the pressure is fully transmitted and penetrates into the powder body, so that the density distribution is uniform. The pressurization rate is preferably 5~10MPa / min, more preferably 6~8MPa / min. This pressurization rate can prevent excessively fast pressurization from causing uneven deformation of the flexible mold or an increase in the density gradient inside the powder body.

[0034] In this invention, the pressure of cold isostatic pressing of the second mixed powder is preferably 150~200MPa, more preferably 160~180MPa. Under this moderate pressure, the Al powder, which is relatively soft and has good plasticity, can be well densified. Excessive pressure can easily produce a "hard shell" effect. The holding time is preferably 5~10min, more preferably 6~8min. This holding time can ensure that the pressure is fully transmitted and penetrates into the powder body, so that the density distribution is uniform. The pressurization rate is preferably 5~10MPa / min, more preferably 6~8MPa / min. This pressurization rate can prevent excessively rapid pressurization from causing uneven deformation of the flexible mold or an increase in the density gradient inside the powder body.

[0035] In this invention, the thickness of each layer of the first mixed powder is preferably 50~300μm, more preferably 80~200μm. The thickness of each layer of the first mixed powder can be the same or different. The thickness of each layer of the second mixed powder is preferably 30~200μm, more preferably 50~150μm. The thickness of each layer of the second mixed powder can be the same or different. Specifically, in some embodiments of this invention, the physical thickness of a single layer of the second mixed powder (Al+TC4) should generally be less than the physical thickness of a single layer of the first mixed powder (Ti+TC4), but ultimately it is necessary to ensure that the total Al / Ti atomic ratio of the entire system is slightly greater than 1. Specifically, it can be (1.05~1.15):1, such as 1.05:1, 1.1:1, 1.15:1, preferably a range of values ​​with the above values ​​as the upper or lower limit.

[0036] After obtaining the pre-coated titanium-aluminum coating, the present invention places the titanium alloy component with the pre-coated titanium-aluminum coating on a support, using, as follows: Figure 1 The device shown applies pulsed current treatment to the pre-formed titanium-aluminum coating on the surface of a titanium alloy component, thereby heating and melting the pre-formed titanium-aluminum coating in a non-contact manner. The support can drive the titanium alloy component to rotate around its axis. During the pulsed current treatment, the temperature of the pre-formed titanium-aluminum coating is monitored in real time using a temperature measuring device. When the temperature reaches 1200°C, the jet nozzle is opened to rapidly cool the heated area and surrounding area until it reaches room temperature. Then, the pulse power supply is moved to perform the same operation on the next area until the entire titanium-aluminum coating has been treated with pulsed current.

[0037] This invention utilizes ultra-high cooling speed (>10) 6 Cooling the coating after pulse current treatment with K / s can form a nanocrystalline / amorphous composite structure.

[0038] In this invention, the preferred current density for the pulsed current processing is 5 × 10³ A / cm². 2 ~1×10 5 A / cm2 More preferably 1×10 4 A / cm 2 ~5×10 5 A / cm 2 For example, 5×10³A / cm 2 1×10 4 A / cm 2 2×10 4 A / cm 2 3×10 4 A / cm 2 4×10 4 A / cm 2 5×10 4 A / cm 2 6×10 4 A / cm 2 7×10 4 A / cm 2 8×10 4 A / cm 2 9×10 4 A / cm 2 1×10 5 A / cm 2 2×10 5 A / cm 2 3×10 5 A / cm 2 4×10 5 A / cm 2 5×10 5 A / cm 2 The pulse frequency is preferably within the range of any of the above values ​​as the upper or lower limit; the pulse frequency is preferably 50Hz~500Hz, more preferably 100Hz~400Hz, such as 50 Hz, 100 Hz, 150Hz, 200 Hz, 250 Hz, 300 Hz, 350 Hz, 400 Hz, 450 Hz, 500 Hz, preferably within the range of any of the above values ​​as the upper or lower limit; the single pulse energy is preferably 5J / cm². 2 ~50 J / cm 2 More preferably 10 J / cm 2 ~45 J / cm 2 , such as 5J / cm 2 10 J / cm 2 15 J / cm 2 20 J / cm 2 25 J / cm 2 30 J / cm 2 35 J / cm 2 40 J / cm2 45 J / cm 2 50J / cm 2 The preferred values ​​are those within the range of the above-mentioned values, with the upper or lower limit being any of the above values. The single pulse width is preferably 10μs to 400μs, more preferably 50μs to 350μs, such as 10μs, 50μs, 100μs, 150μs, 200μs, 250μs, 300μs, 350μs, 400μs, preferably within the range of the above-mentioned values, with the upper or lower limit being any of the above-mentioned values. The pulse current processing time is preferably 30s to 180s, more preferably 50s to 150s, such as 30s, 40s, 50s, 60s, 70s, 80s, 90s, 100s, 110s, 120s, 130s, 140s, 150s, 160s, 170s, 180s. The value of s is preferably a range of values ​​with the above values ​​as the upper or lower limit; the number of pulses is preferably 1 to 10 times, more preferably 3 to 8 times, with a 1-second cooling interval between each pulse.

[0039] This invention utilizes TC4 (Ti-6Al-4V) powder as the titanium source, whose Al / V element ratio can suppress the formation of the brittle Ti3Al phase. The Al+TC4 layer acts as a reaction flux, lowering the synthesis temperature and facilitating interfacial chemical reactions between Al and Ti. The Ti+TC4 mixed layer provides excess Ti to compensate for diffusion losses. During pulsed current treatment, Ti and Al in the coating react, producing a product with 70%–85% γ-TiAl (the main reinforcing phase, providing high-temperature strength), 10%–20% α2-Ti3Al (enhancing toughness), and <5% TiAl3 + TiAl2 (the transition phase, promoting densification), resulting in a dense TiAl nanocrystalline coating.

[0040] After pulsed current processing, the TC4 titanium alloy component is removed and its surface is subjected to fluorescence detection, thus obtaining a titanium alloy component with a high-strength and high-toughness surface coating.

[0041] This invention provides a high-strength, high-toughness titanium-aluminum coating, prepared according to the method described above. The high-strength, high-toughness titanium-aluminum coating comprises n stacked sublayers (1≤n≤15), each sublayer including a first sublayer and a second sublayer. The first sublayer is a densified layer formed from a first mixed powder by cold isostatic pressing and pulsed current treatment, with a thickness of 30~150μm, preferably 50~100μm. The second sublayer is a densified layer formed from a second mixed powder by cold isostatic pressing and pulsed current treatment, with a thickness preferably 20~100μm, more preferably 30~70μm. The component ratios of the first mixed powder and the second mixed powder are consistent with those described above, and will not be repeated here.

[0042] In this invention, the thickness of the high-strength and high-toughness titanium-aluminum coating is preferably 5-10 mm.

[0043] The present invention also provides an application of the high-strength and high-toughness titanium-aluminum coating as described above in titanium alloy shaft components, especially TC4 titanium alloy shaft components.

[0044] This invention provides a method for preparing a high-strength, high-toughness titanium-aluminum coating, comprising the following steps: A) layering a first mixed powder and a second mixed powder on the surface of a titanium alloy component to obtain a pre-formed titanium-aluminum coating; the first mixed powder comprises Ti powder and TC4 powder; the second mixed powder comprises Al powder and TC4 powder; B) subjecting the pre-formed titanium-aluminum coating to pulsed current treatment to obtain a high-strength, high-toughness titanium-aluminum coating; the current density of the pulsed current treatment is 5 × 10³ A / cm². 2 ~1×10 5 A / cm 2 The single-pulse energy is 5 J / cm². 2 ~50 J / cm 2 This invention achieves gradient thermal expansion coefficient matching by setting multiple TC4 alloy transition layers, reducing interfacial stress. The pulsed instantaneous energy of pulsed current treatment enables local micro-area remelting of the coating and inhibits grain growth, obtaining submicron-level equiaxed crystals. Electromagnetic force induces dislocation slip to release residual stress, and the in-situ exothermic reaction promotes element interdiffusion, forming a metallurgical bonding interface, improving the strength and toughness of the coating. Experimental results show that the titanium-aluminum coating prepared by the method of this invention has a hardness of 850~1100HV0.3, fracture toughness KIC≥25 MPa·m¹ / ², and coating bonding strength≥150 MPa, which is about 30% higher than that of the traditional process. The oxidation weight gain at 1100℃ is <1.0 (mg / cm²·100h), and the coating porosity is reduced to ≤0.5% (traditional process ≥2%). The cycle life (1100℃↔ room temperature) is >500 times (traditional <200 times).

[0045] To further illustrate the present invention, the following detailed description of a high-strength and high-toughness titanium-aluminum coating, its preparation method, and its application are provided in conjunction with embodiments, but should not be construed as limiting the scope of protection of the present invention.

[0046] Example 1

[0047] Step 1: Part Design Preparation

[0048] The TC4 titanium alloy shaft part is 1000mm long, 210mm outer diameter, and 110mm inner diameter.

[0049] Step 2: Preparation of Raw Materials

[0050] Take 700-800mm TC4 titanium alloy bars and hot extrude them to obtain tubes with a length of 1000-1100mm, an outer diameter of 200-205mm, and an inner diameter of 110mm, i.e., TC4 titanium alloy tube blanks.

[0051] Step 3: Prefabrication of the reinforcement layer

[0052] Take Ti powder (particle size D90 ≤ 20 μm) and TC4 powder (particle size 45-106 μm) in a 1:1 mass ratio and mix them. Then take Al powder (particle size D90 ≤ 25 μm) and TC4 powder (particle size 45-106 μm) in a 1:1 mass ratio and mix them. Using cold isostatic pressing, spread the powder evenly on the surface of the TC4 titanium alloy tube blank. First, spread a layer of Ti powder and TC4 powder mixture (150 μm thick) and press it at 230 MPa for 12 minutes. Then spread a layer of Al powder and TC4 powder mixture (100 μm thick) and press it at 170 MPa for 6 minutes. Continue this process until the total number of layers is 4 (total thickness is about 500 μm).

[0053] Step 4: Pulse Current Processing

[0054] The pre-formed reinforced TC4 titanium alloy tube blank is placed on the support (2), which can drive the TC4 titanium alloy tube blank to rotate around the axis at a speed of 15 RPM. The pulse power supply (5) is started and the parameters are set as follows: voltage: 6 kV, current density: 8000 A / cm², pulse frequency: 200 Hz, single pulse energy: 30 J / cm², single pulse width: 300 μs, processing time: 100 s, number of pulses: 5 (with a 1 s interval for cooling). The reinforced layer is heated and melted non-contactly. The temperature of the reinforced layer is monitored in real time using an infrared thermometer. When it reaches 1200℃, the jet nozzle (6) is opened to rapidly cool the heated area and surrounding area at a wind speed of 10 m / s (cooling it to below 80℃). Then, the pulse power supply (5) is moved along the tube blank axis to the next area (overlap rate 20%) and the same operation is performed until the entire reinforced layer on the surface of the tube blank is processed.

[0055] Step 5: Post-processing

[0056] The TC4 titanium alloy tube blank is removed and its surface is subjected to fluorescence detection to obtain a titanium alloy tube blank with a high-strength and high-toughness surface coating.

[0057] Example 2

[0058] Step 1: Part Design Preparation

[0059] The TC4 titanium alloy shaft part is 1000mm long, 210mm outer diameter, and 110mm inner diameter.

[0060] Step 2: Preparation of Raw Materials

[0061] Take 700-800mm TC4 titanium alloy bars and hot extrude them to obtain tubes with a length of 1000-1100mm, an outer diameter of 200-205mm, and an inner diameter of 110mm, i.e., TC4 titanium alloy tube blanks.

[0062] Step 3: Prefabrication of the reinforcement layer

[0063] Take Ti powder (particle size 15±5 μm) and TC4 powder (particle size 75±25 μm) in a 1:1 mass ratio and mix them. Then take Al powder (particle size 20±5 μm) and TC4 powder (particle size 75±25 μm) in a 1:1 mass ratio and mix them. Using cold isostatic pressing, spread the powder evenly on the surface of the TC4 titanium alloy tube blank. First, spread a layer of Ti powder and TC4 powder mixture (thickness 80 μm) and press it at 220 MPa for 15 minutes. Then spread a layer of Al powder and TC4 powder mixture (thickness 80 μm) and press it at 220 MPa for 15 minutes. Continue this process until the total number of layers is 8 (total thickness approximately 640 μm).

[0064] Step 4: Pulse Current Processing

[0065] The pre-reinforced TC4 titanium alloy tube blank was placed on a support and rotated at 10 RPM. The pulse power supply was activated with the following parameters set: voltage: 8 kV, current density: 10000 A / cm², pulse frequency: 300 Hz, single pulse energy: 40 J / cm², single pulse width: 200 μs, processing time: 150 s, number of pulses: 8 (with a 1-s cooling interval). Temperature monitoring and control were the same as in Example 1 (trigger temperature 1200℃, cooled to below 80℃), with a movement overlap rate of 20%.

[0066] Step 5: Post-processing

[0067] The TC4 titanium alloy tube blank is removed and its surface is subjected to fluorescence detection to obtain a titanium alloy tube blank with a high-strength and high-toughness surface coating.

[0068] Example 3

[0069] Step 1: Part Design Preparation

[0070] The TC4 titanium alloy shaft part is 1000mm long, 210mm outer diameter, and 110mm inner diameter.

[0071] Step 2: Preparation of Raw Materials

[0072] Take 700-800mm TC4 titanium alloy bars and hot extrude them to obtain tubes with a length of 1000-1100mm, an outer diameter of 200-205mm, and an inner diameter of 110mm, i.e., TC4 titanium alloy tube blanks.

[0073] Step 3: Prefabrication of the reinforcement layer

[0074] Take Ti powder (particle size ≤20 μm) and TC4 powder (particle size 45-106 μm) in a mass ratio of 1:1 and mix them. Then take Al powder (particle size 10±5 μm) and TC4 powder (particle size 45-106 μm) in a mass ratio of 2:1 and mix them. Using cold isostatic pressing, spread the powder evenly on the surface of the TC4 titanium alloy tube blank. First, spread a layer of Ti powder and TC4 powder mixture (thickness 120 μm), press it at 180 MPa for 8 minutes, then spread a layer of Al powder and TC4 powder mixture (thickness 100 μm), press it at 180 MPa for 8 minutes, and so on, until the total number of layers is 6 (total thickness is about 660 μm).

[0075] Step 4: Pulse Current Processing

[0076] The pre-reinforced TC4 titanium alloy tube blank was placed on a support and rotated at 12 RPM. The pulse power supply was activated with the following parameters set: voltage: 5 kV, current density: 6000 A / cm², pulse frequency: 150 Hz, single pulse energy: 25 J / cm², single pulse width: 400 μs, processing time: 120 s, number of pulses: 4 (with a 2-s cooling interval). Temperature monitoring and control were the same as in Example 1 (trigger temperature 1180 ℃, cooled to below 80 ℃), with a movement overlap rate of 25%.

[0077] Step 5: Post-processing

[0078] The TC4 titanium alloy tube blank is removed and its surface is subjected to fluorescence detection to obtain a titanium alloy tube blank with a high-strength and high-toughness surface coating.

[0079] The process parameters in Examples 1 to 3 are shown in Table 1.

[0080] Table 1 Process parameters in Examples 1-3

[0081]

[0082] Comparative Example 1

[0083] Step 1: Part Design Preparation

[0084] The TC4 titanium alloy shaft part is 1000mm long, 210mm outer diameter, and 110mm inner diameter.

[0085] Step 2: Preparation of Raw Materials

[0086] Take 700-800mm TC4 titanium alloy bars and hot extrude them to obtain tubes with a length of 1000-1100mm, an outer diameter of 200-205mm, and an inner diameter of 110mm, i.e., TC4 titanium alloy tube blanks.

[0087] Step 3: Prefabrication of the reinforcement layer

[0088] Ti powder (particle size D90 ≤ 20 μm), Al powder (particle size D90 ≤ 25 μm), and TC4 powder (particle size 45-106 μm) were mixed in a mass ratio of 1:1:1. The mixed powder was then uniformly spread on the surface of the TC4 titanium alloy tube blank using cold isostatic pressing (pressure: 200 MPa, holding time: 10 minutes) to form a single layer with a thickness of 500 μm (the same as the total thickness in Example 1).

[0089] Step 4: Heating in the resistance furnace

[0090] The TC4 titanium alloy tube blank with the pre-reinforced layer was heated in an argon protective atmosphere at 1100℃ for 30 minutes using a resistance furnace.

[0091] Result: Due to the intense Ti-Al reaction (thermal explosion reaction), a large amount of heat was released instantaneously, resulting in localized ablation and spattering of the coating, and causing the TC4 titanium alloy substrate surface to melt through, making it impossible to form a complete coating.

[0092] Comparative Example 2

[0093] Step 1: Part Design Preparation

[0094] The TC4 titanium alloy shaft part is 1000mm long, 210mm outer diameter, and 110mm inner diameter.

[0095] Step 2: Preparation of Raw Materials

[0096] Take 700-800mm TC4 titanium alloy bars and hot extrude them to obtain tubes with a length of 1000-1100mm, an outer diameter of 200-205mm, and an inner diameter of 110mm, i.e., TC4 titanium alloy tube blanks.

[0097] Step 3: Prefabrication of the reinforcement layer

[0098] Only Ti powder (particle size D90 ≤ 20 μm) and Al powder (particle size D90 ≤ 25 μm) were used. Using cold isostatic pressing (pressure: 200 MPa, holding time: 10 minutes), the powders were evenly spread on the surface of the TC4 titanium alloy tube blank. First, a layer of pure Ti powder (150 μm thick) was spread and held at 230 MPa for 12 minutes, followed by a layer of pure Al powder (100 μm thick) and held at 170 MPa for 6 minutes. This process was repeated until a total of 4 layers were laid (total thickness approximately 500 μm, consistent with Example 1).

[0099] Step 4: Pulse Current Processing

[0100] Same as Example 1.

[0101] Step 5: Post-processing

[0102] The TC4 titanium alloy tube blank is removed and its surface is subjected to fluorescence detection to obtain a titanium alloy tube blank with a high-strength and high-toughness surface coating.

[0103] The coatings in the examples and comparative examples were tested for performance, and the results are shown in Table 2.

[0104] Table 2 Performance parameters of the coatings in the examples and comparative examples

[0105]

[0106] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a high-strength, high-toughness titanium-aluminum coating, comprising the following steps: A) A first mixed powder and a second mixed powder are laid layer by layer on the surface of a titanium alloy component to obtain a pre-made titanium-aluminum coating; The first mixed powder comprises Ti powder and TC4 powder; the second mixed powder comprises Al powder and TC4 powder. B) The pre-fabricated titanium-aluminum coating is subjected to pulsed current treatment to obtain a high-strength and high-toughness titanium-aluminum coating. The current density of the pulse current processing is 5 × 10³ A / cm² 2 ~1×10 5 A / cm 2 The single-pulse energy is 5 J / cm². 2 ~50J / cm 2 .

2. The method for preparing a high-strength, high-toughness titanium-aluminum coating according to claim 1, characterized in that, The titanium alloy component is a TC4 titanium alloy component.

3. The method for preparing a high-strength, high-toughness titanium-aluminum coating according to claim 1, characterized in that, In the first mixed powder, the mass ratio of Ti powder to TC4 powder is (0.8~2.0):

1.

4. The method for preparing a high-strength, high-toughness titanium-aluminum coating according to claim 1, characterized in that, In the second mixed powder, the mass ratio of Al powder to TC4 powder is (0.8~2.0):

1.

5. The method for preparing a high-strength, high-toughness titanium-aluminum coating according to claim 1, characterized in that, The first and second mixed powders are laid layer by layer on the surface of the titanium alloy component by cold isostatic pressing.

6. The method for preparing a high-strength, high-toughness titanium-aluminum coating according to claim 1, characterized in that, The pulse frequency of the pulse current processing is 50Hz~500Hz, and the single pulse width is 10~400.

7. The method for preparing a high-strength, high-toughness titanium-aluminum coating according to claim 1, characterized in that, The processing time for the pulse current processing is 30s to 180s, and the number of pulses is 1 to 10.

8. The method for preparing a high-strength, high-toughness titanium-aluminum coating according to claim 1, characterized in that, During the pulsed current treatment process, when the coating temperature reaches 1200~1250℃, the treated area is rapidly cooled by air until it is cooled to room temperature.

9. A high-strength and high-toughness titanium-aluminum coating, prepared according to the preparation method of any one of claims 1 to 8, wherein the thickness of the high-strength and high-toughness titanium-aluminum coating is 5 to 10 mm.

10. The application of the high-strength and high-toughness titanium-aluminum coating as described in claim 9 in titanium alloy shaft components.

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