A high-temperature wear-resistant coating material for titanium alloy blade tips and its laser cladding method

Abstract

This invention relates to a high-temperature wear-resistant coating material for titanium alloy blade tips. The coating material is made from the following powder raw materials by mass percentage: 3.0~8.0% Al, 2.0~5.0% V, 0.03~0.2% Fe, 0.01~0.1% Si, 0.2~0.5% C, with the balance being Ti. The invention also discloses a laser cladding method for this coating material. The high-temperature wear-resistant coating prepared by this invention has a uniform and dense structure, free from cracks and pores, and exhibits excellent tribological properties, providing long-term and effective high-temperature wear protection for titanium alloy blade tips.

Description

Technical Field

[0001] This invention relates to the field of laser cladding technology, and in particular to a high-temperature wear-resistant coating material for the tip of a titanium alloy blade and its laser cladding method. Background Technology

[0002] With the increasing demand for lightweight aero engines and the continuous improvement of thrust-to-weight ratio, titanium alloys have become the primary material for important components such as compressor blades and casings. However, due to the low hardness, poor wear resistance, and poor plastic shear resistance of titanium alloys, when used in compressor blades, the extremely high scraping speed and instantaneous temperature rise cause severe friction between the blade tip and the inner wall of the casing, resulting in severe blade tip wear. This leads to radial airflow loss, affecting engine efficiency, and the intense friction can even trigger a "titanium fire," seriously threatening engine reliability.

[0003] To address the wear problem of titanium alloys, researchers have proposed numerous technical solutions for laser cladding surface treatment to improve the wear resistance of titanium alloys. Examples include: CN 115094417A, "High Wear-Resistant Nickel-Based Laser Cladding Powder for Titanium Alloy Surface and its Laser Cladding Method"; CN 116121751A, "A Self-Lubricating Wear-Resistant Composite Coating and its Ultra-High-Speed ​​Laser Cladding Method," which proposes using laser cladding technology to prepare a nickel-based wear-resistant coating on the surface of titanium alloys to improve their wear resistance; CN 116607146A, "A Composite Wear-Resistant Coating for TC4 Titanium Alloy Surface and its Preparation Method," which uses TC4 particles as the base component, mixes them with WC particles in a certain proportion, and then prepares the coating on the surface of titanium alloys using a laser cladding process; and CN117821962A, which uses laser cladding technology to design and prepare a friction-reducing and wear-resistant titanium alloy coating with hexagonal boron nitride as the reinforcing phase and three lubricating phases.

[0004] Currently, the preparation of wear-resistant coatings on titanium alloy surfaces by laser cladding generally faces two main problems: First, the wear-resistant reinforcing phase in the coating is mainly prepared by direct addition, resulting in poor wettability with the coating matrix phase and weak interfacial bonding. This leads to the easy detachment of the reinforcing phase during high-speed, heavy-load friction, resulting in a high coefficient of friction. Second, nickel-based alloys are often used as the coating matrix phase. However, due to significant differences in thermophysical properties between nickel and the titanium alloy matrix, and their poor metallurgical compatibility, a violent metallurgical reaction occurs during laser cladding, forming hardened intermetallic compounds that cause coating cracking and low bonding strength with the titanium alloy matrix. Furthermore, existing solutions primarily focus on the wear resistance of laser coatings on titanium alloy surfaces, often neglecting the bonding strength and the high coefficient of friction caused by the detachment of the wear-resistant reinforcing phase for coatings applied to the tips of titanium alloy blades under high-speed, heavy-load conditions. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a high-temperature wear-resistant coating material for the tip of titanium alloy blades with high bonding strength, low coefficient of friction, and low wear rate.

[0006] Another technical problem to be solved by the present invention is to provide a laser cladding method for using the high-temperature wear-resistant coating material at the tip of the titanium alloy blade.

[0007] To solve the above problems, the present invention provides a high-temperature wear-resistant coating material for titanium alloy blade tips, characterized in that: the coating material is made from the following powder raw materials by mass percentage: 3.0~8.0% Al, 2.0~5.0% V, 0.03~0.2% Fe, 0.01~0.1% Si, 0.2~0.5% C, with the balance being Ti.

[0008] The powder raw materials Al, V, Fe, Si, C, and Ti are all powders with a purity greater than 99%.

[0009] The preparation method of the high-temperature wear-resistant coating material for the tip of a titanium alloy blade as described above is characterized in that: the coating material is prepared by gas atomization, in which Al, V, Fe, Si and Ti alloying elements are melted and atomized into spherical powder with a particle size of 45~125 µm; then the spherical powder and C powder are ball-milled at a speed of 80~100 r / min for 4~6 h and mixed evenly to obtain the coating material.

[0010] A laser cladding method using the coating material described above is characterized in that: TC17 titanium alloy is used as the blade material, and a fiber laser is used to prepare a titanium-based high-temperature wear-resistant coating on the tip of the TC17 titanium alloy blade using laser cladding technology.

[0011] The laser cladding method described above includes the following steps:

[0012] S1 first sandblasts the titanium alloy blade blank, then cleans it with anhydrous ethanol, and then dries it with compressed air to obtain the pre-treated blade blank.

[0013] S2. The pretreated blade blank is placed in a muffle furnace for preheating treatment to obtain the heat-treated blade.

[0014] S3 uses the coaxial powder feeding method to laser clad the coating material on the tip of the heat-treated blade to obtain the clad sample.

[0015] S4 The cladding sample is subjected to stress-relief annealing and then cooled to room temperature in the furnace to obtain a titanium-based high-temperature wear-resistant coating.

[0016] In step S1, the sand used for sandblasting is SiO2, and the sandblasting air pressure is 0.2~0.4 MPa.

[0017] The preheating temperature in step S2 is 400~600 ℃, and the preheating time is 20~40 min.

[0018] The laser cladding process conditions in step S3 are as follows: laser power of 2400~3000 W, scanning speed of 200~400 mm / min, overlap rate of 20~40%, powder feeding rate of 10~15 g / min, protective gas of argon, and gas pressure of 0.1~0.3 MPa.

[0019] The stress-relief annealing conditions in step S4 refer to an annealing temperature of 450~600 ℃ and a holding time of 4~6 h.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] 1. The coating material of this invention is composed of titanium-based alloy, which has good compatibility and matching with titanium alloy substrate, which is beneficial to improving the bonding strength between the coating and titanium alloy substrate, with the bonding strength reaching more than 800 MPa.

[0022] 2. The addition of carbon (C) to the coating material of this invention, along with the excellent affinity between titanium (Ti) and carbon, allows for the in-situ synthesis of the wear-resistant reinforcing phase TiC via laser. This improves the wettability and dispersion uniformity between the matrix phase and the wear-resistant reinforcing phase, thereby enhancing the interfacial bonding and preventing the wear-resistant reinforcing phase from detaching under high-speed, heavy-load service conditions. Furthermore, given that TiC's thermal expansion coefficient, density, and other physical properties are similar to those of titanium-based alloys, the high hardness, high modulus, and good high-temperature stability of TiC improve the wear resistance of the titanium-based coating, thus meeting the application requirements for low friction and wear resistance under high-speed, heavy-load conditions. The introduction of TiC also increases the coating hardness, resulting in a Vickers hardness greater than 550 HV5.

[0023] 3. The high-temperature wear-resistant coating prepared by this invention has a uniform and dense structure, free from defects such as cracks and pores. When it is compared with the wear-resistant coating material Ni-Cr-Al / Ni-Cg on the inner surface of the casing under high-speed and heavy-load conditions in the laboratory, the wear-resistant coating reduces the friction coefficient by more than 50% and the wear rate by more than two orders of magnitude compared with the titanium alloy substrate. Attached Figure Description

[0024] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0025] Figure 1 This is a cross-sectional morphology diagram of the high-temperature wear-resistant coating prepared in Example 1 of the present invention.

[0026] Figure 2 The bonding strength between the high-temperature wear-resistant coatings prepared in Examples 1-3 of this invention and the titanium alloy substrate. Detailed Implementation

[0027] A high-temperature wear-resistant coating material for the tip of a titanium alloy blade, wherein the coating material is made from the following powder raw materials by mass percentage (in grams): 3.0~8.0% Al, 2.0~5.0% V, 0.03~0.2% Fe, 0.01~0.1% Si, 0.2~0.5% C, with the balance being Ti.

[0028] Among them, the powder raw materials Al, V, Fe, Si, C and Ti are all powders with a purity greater than 99%.

[0029] A method for preparing a high-temperature wear-resistant coating material for titanium alloy blade tips is disclosed. The coating material is prepared using a gas atomization method: Al, V, Fe, Si, and Ti alloying elements are melted and atomized into spherical powders with a particle size of 45–125 µm; then, the spherical powders are ball-milled with C powder at a speed of 80–100 r / min for 4–6 h until uniformly mixed. The use of a relatively low rotation speed ensures the integrity of the spherical powders.

[0030] A laser cladding method using the above-mentioned coating material: Using TC17 titanium alloy as the blade material (also applicable to other titanium alloys), a fiber laser is used to prepare a titanium-based high-temperature wear-resistant coating on the tip of the TC17 titanium alloy blade using laser cladding technology. During the fiber laser cladding process, C powder reacts in situ with titanium-based alloy powder to generate the wear-resistant reinforcing phase TiC.

[0031] The specific method includes the following steps:

[0032] S1 first performs sandblasting on the titanium alloy blade blank, using SiO2 as the sand and a sandblasting pressure of 0.2~0.4MPa. Afterwards, it is cleaned with anhydrous ethanol and dried with compressed air to obtain the pretreated blade blank.

[0033] S2 The pretreated blade blank is placed in a muffle furnace and preheated at 400~600 ℃ for 20~40 min to reduce the temperature gradient and residual stress during the laser cladding process and eliminate defects in the coating, thus obtaining the heat-treated blade.

[0034] S3 employs a coaxial powder feeding method to laser-clad the coating material onto the tip of the heat-treated blade, thus obtaining the clad sample. The laser cladding process conditions are as follows: laser power of 2400~3000 W, scanning speed of 200~400 mm / min, overlap rate of 20~40%, powder feeding rate of 10~15 g / min, protective gas of argon, and gas pressure of 0.1~0.3 MPa.

[0035] S4 The cladding sample is subjected to stress-relief annealing at 450~600 ℃ for 4~6 h to further reduce the residual stress in the coating. Then, it is cooled to room temperature in the furnace to obtain the titanium-based high-temperature wear-resistant coating.

[0036] Example 1

[0037] A high-temperature wear-resistant coating was prepared on the tip of a titanium alloy blade using laser cladding technology. The specific steps are as follows:

[0038] S1 prepared titanium-based powder obtained by gas atomization and C powder at a mass ratio (g / g) of 99.8:0.2, and then ball-milled them at a speed of 100 r / min for 4 h. The ball-milled powder was then set aside for later use. The composition (g) of the titanium-based powder was: Al 8 wt.%, V 5 wt.%, Fe 0.2 wt.%, Si 0.1 wt.%, Ti 86.5 wt.%.

[0039] The S2 TC17 titanium alloy blade blanks were sandblasted using SiO2 abrasive at a pressure of 0.3 MPa. After sandblasting, the blanks were cleaned with anhydrous ethanol and then dried with compressed air for later use.

[0040] S3 places the cleaned TC17 titanium alloy blade blank into a muffle furnace for preheating treatment at a temperature of 400℃ for 40 minutes to reduce the temperature gradient and residual stress during the laser cladding process and eliminate defects in the coating.

[0041] S4 loads the mixed titanium-based powder into the powder feeder and uses a fiber laser to clad a high-temperature wear-resistant coating on the tip of the preheated titanium alloy blade blank. The cladding process is as follows: laser power 2400 W, scanning speed 200 mm / min, overlap rate 37%, powder feeding rate 10 g / min, protective gas is argon, and gas pressure is 0.1 MPa.

[0042] S5 subjected the TC17 titanium alloy blade blank obtained after laser cladding to stress-relief annealing at a temperature of 600℃ for 4 hours, and then cooled to room temperature in the furnace.

[0043] The microstructure of the high-temperature wear-resistant coating prepared in Example 1 was observed, such as... Figure 1 As shown. By Figure 1 It can be seen that the coating has a uniform structure, dense organization, no obvious defects such as pores and cracks, and exhibits good metallurgical bonding with the titanium alloy substrate.

[0044] Example 2

[0045] The coating material and high-temperature wear-resistant coating were prepared according to the method of Example 1, except that titanium-based powder and C powder were mixed at a mass ratio (g / g) of 99.6:0.4 and then ball-milled. The composition (g) of the titanium-based powder was: Al 6 wt.%, V 3 wt.%, Fe 0.12 wt.%, Si 0.06 wt.%, Ti 90.42 wt.%. Laser cladding process: laser power 3000 W, scanning speed 400 mm / min, overlap rate 37%, powder feeding rate 15 g / min.

[0046] Example 3

[0047] The coating material and high-temperature wear-resistant coating were prepared according to the method of Example 1, except that titanium-based powder and C powder were mixed at a mass ratio (g / g) of 99.5:0.5 and then ball-milled. The composition (g) of the titanium-based powder was: Al 3 wt.%, V 2 wt.%, Fe 0.03 wt.%, Si 0.01 wt.%, Ti 94.46 wt.%. Laser cladding process: laser power 3000 W, scanning speed 400 mm / min, overlap rate 40%, powder feeding rate 15 g / min.

[0048] The Vickers hardness, bond strength, and high-temperature wear resistance of the high-temperature wear-resistant coatings prepared in Examples 1-3 were tested according to the following method:

[0049] (1) Vickers hardness

[0050] The Vickers hardness of the coating surface was tested using an SVD-4052TS Vickers hardness tester with a load of 5000 gf and a holding time of 10 s. The test results are listed in Table 1.

[0051] Table 1. Vickers hardness of the high-temperature wear-resistant coatings prepared in Examples 1-3

[0052]

[0053] (2) High-temperature tribological properties

[0054] Test conditions: A high-temperature wear-resistant coating was laser-coated onto the surface of TC17 titanium alloy. After the coating surface was polished smooth, a friction sample with dimensions of Φ24×4mm was machined as a disc. The corresponding friction pair was a TC17 pin with a diameter of Φ6.35 mm. The friction area was sprayed with a wear-resistant coating Ni-Cr-Al / Ni-Cg with a diameter of Φ0.6 mm. The test temperature was 500 ℃, the motion mode was rotary sliding, the rotation radius was 5 mm, the load was 100 N, and the rotation speed was 360 rpm. The test results are listed in Table 2.

[0055] Table 2. Tribological properties of the high-temperature wear-resistant coatings prepared in Examples 1-3

[0056]

[0057] (3) Bond strength

[0058] A 3 mm deep, 45° V-shaped groove was machined on the surface of the TC17 titanium alloy sample, and then the V-shaped groove was filled using the laser cladding process described in Examples 1-3. A dumbbell-shaped sample with a thickness of 2 mm was cut from the joint perpendicular to the cladding direction. After the sample was machined, the cladding area was located at the midpoint of the parallel length of the sample. According to GB / T228.1-2021 standard, a universal testing machine was used with a loading rate of 0.5 mm / min, and the test force was continuously applied until the sample fractured to obtain the bonding strength between the coating and the substrate. Figure 2 The stress-strain curves of the bonding strength of the samples show that the bonding strengths of the coatings obtained by the laser cladding processes of Examples 1-3 with the titanium alloy substrates are 836 MPa, 821 MPa and 815 MPa, respectively.

[0059] In summary, the high-temperature wear-resistant coating for titanium alloy blade tips provided by this invention has a dense structure, free from defects such as cracks and pores; the coating exhibits high Vickers hardness and strong bonding strength with the titanium alloy substrate. When worn against the wear-resistant coating material Ni-Cr-Al / Ni-Cg on the inner surface of the casing under high-speed, heavy-load conditions, the coating demonstrates excellent tribological properties, providing long-term and effective high-temperature wear protection for titanium alloy blade tips.

[0060] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A laser cladding method for applying a high temperature wear resistant coating material to the tip of a titanium alloy blade, characterized by: The application discloses a method for preparing a titanium-based high-temperature wear-resistant coating on a TC17 titanium alloy blade tip by adopting a fiber laser and a laser cladding technique, and relates to the field of laser cladding techniques.The coating material is prepared from the following powder raw materials in percentage by mass: 3.0-8.0% Al, 2.0-5.0% V, 0.03-0.2% Fe, 0.01-0.1% Si, 0.2-0.5% C, and the balance of Ti.The coating material is prepared by adopting a gas atomization method: Al, V, Fe, Si and Ti alloy elements are melted and atomized into spherical powder with a particle size of 45-125 µm; the spherical powder is mixed with C powder by ball milling at a rotating speed of 80-100 r / min for 4-6 h, and the mixture is obtained; the method comprises the following steps: S1, a titanium alloy blade blank is first subjected to sand blasting treatment, then cleaned with anhydrous ethanol, and dried by compressed air, so as to obtain a pretreated blade blank; S2, the pretreated blade blank is placed into a muffle furnace for preheating treatment, so as to obtain a heat-treated blade; S3, a coaxial powder feeding method is adopted to laser cladding the coating material on the blade tip of the heat-treated blade, so as to obtain a cladding sample; the process conditions of the laser cladding are that the laser power is 2400-3000 W, the scanning speed is 200-400 mm / min, the overlapping rate is 20-40%, the powder feeding rate is 10-15 g / min, the protective gas is argon, and the gas pressure is 0.1-0.3 MPa; S4, the cladding sample is subjected to stress relief annealing treatment, and then cooled to room temperature in the furnace, so as to obtain a titanium-based high-temperature wear-resistant coating.

2. A laser cladding method for applying a high temperature wear resistant coating material to the tip of a titanium alloy blade as claimed in claim 1, characterized in that: The powder raw materials Al, V, Fe, Si, C and Ti are all powders with a purity of greater than 99%.

3. The method of claim 1, wherein the laser cladding method is characterized by: In the step S1, the sand used for sand blasting is SiO2, and the sand blasting air pressure is 0.2-0.4 MPa.

4. The method of claim 1, wherein the laser cladding method is characterized by: In the step S2, the preheating treatment temperature is 400-600 ℃, and the preheating time is 20-40 min.

5. The method of claim 1, wherein the laser cladding method is characterized by: In the step S4, the stress relief annealing treatment conditions are that the annealing temperature is 450-600 ℃, and the holding time is 4-6 h.

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