Titanium alloy blade tip high-temperature wear-resistant coating material and laser cladding method thereof

Abstract

The invention relates to a high-temperature wear-resistant coating material for a titanium alloy blade tip. The coating material is prepared from the following powder raw materials in percentage by mass: 3.0 to 8.0 percent of Al, 2.0 to 5.0 percent of V, 0.03 to 0.2 percent of Fe, 0.01 to 0.1 percent of Si, 0.2 to 0.5 percent of C and the balance of Ti. Meanwhile, the invention further discloses a laser cladding method of the coating material. The prepared high-temperature wear-resistant coating is uniform and compact in structure, free of cracks, pores and other defects, excellent in friction and wear performance and capable of providing long-term effective high-temperature wear-resistant protection for the titanium alloy blade tip.

Description

Technical Field

[0001] The present invention relates to the technical field of laser cladding, and particularly relates to a high-temperature wear-resistant coating material for the tip of a titanium alloy blade and a laser cladding method thereof. Background Art

[0002] With the demand for lightweight of aero-engines and the continuous improvement of the thrust-to-weight ratio, titanium alloys have become the main materials for important components such as compressor blades and casings. However, due to the low hardness, poor wear resistance and anti-plastic shear performance of titanium alloys, when used for compressor blades, due to the extremely high scraping speed and instantaneous temperature rise, the tip of the blade rubs violently against the inner wall of the casing, and the tip of the blade wears severely, resulting in the reduction of engine efficiency due to radial airflow loss, and the "titanium fire" accident caused by violent friction seriously threatens the reliability of the engine.

[0003] In view of the wear problem of titanium alloys, many technical solutions for improving the wear resistance of titanium alloys by laser cladding surface treatment have been proposed by researchers. For example, the published number CN 115094417A "High-wear-resistant nickel-based laser cladding powder for titanium alloy surface and laser cladding method thereof". CN 116121751A "A self-lubricating wear-resistant composite coating and its ultra-high-speed laser cladding method" proposes to use laser cladding technology to prepare a nickel-based wear-resistant coating on the surface of titanium alloy to improve its wear resistance. The published number CN 116607146A "A composite wear-resistant coating on the surface of TC4 titanium alloy and its preparation method" takes TC4 particles as the basic component, mixes them with WC particles in a certain proportion, and then uses the laser cladding process to prepare them on the surface of titanium alloy. CN117821962A 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 adding three lubricating phases.

[0004] At present, there are generally the following two problems in the preparation of wear-resistant coatings by laser cladding on the surface of titanium alloys: on the one hand, the wear-resistant reinforcing phase in the coating is mainly added by the direct addition method, with poor wettability with the coating matrix phase and weak interfacial bonding. During the high-speed and heavy-load friction process, the reinforcing phase is easy to fall off, resulting in a high friction coefficient; on the other hand, at present, nickel-based alloys are mostly used as the coating matrix phase. Due to the significant difference in thermal physical properties between it and the titanium alloy matrix, and the poor metallurgical compatibility between the two, violent metallurgical reactions occur during the laser cladding process, and hardening intermetallic compounds are formed after the reaction, resulting in coating cracking and low bonding strength with the titanium alloy matrix. And the publicly available solutions mainly focus on the wear resistance of the laser coating on the surface of titanium alloys, while for the surface coating of the tip of titanium alloy blades applied to high-speed and heavy-load working conditions, the bonding strength problem and the problem of high friction coefficient caused by the shedding of wear-resistant reinforcing phases are often ignored. 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 a titanium alloy blade with high bonding strength, low friction coefficient, and small wear rate.

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

[0007] To solve the above problems, a high-temperature wear-resistant coating material for the tip of a titanium alloy blade according to the present invention is characterized in that: the coating material is made of 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, and the balance is Ti.

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

[0009] A 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. The 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 and C powder are ball-milled at a rotation 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 as described above is characterized in that: TC17 titanium alloy is used as the blade material, and a titanium-based high-temperature wear-resistant coating is prepared on the tip of the TC17 titanium alloy blade by laser cladding technology using a fiber laser and the coating material.

[0011] A laser cladding method as described above includes the following steps: S1 The titanium alloy blade blank is first subjected to sandblasting treatment, then cleaned with anhydrous ethanol, and dried with compressed air to obtain the pre-treated blade blank. S2 The pre-treated blade blank is placed in a muffle furnace for preheating treatment to obtain the heat-treated blade. S3 Using the coaxial powder feeding method, the coating material is laser cladded on the tip of the heat-treated blade to obtain the cladding specimen. S4 The cladding specimen is subjected to stress relief annealing treatment and then cooled to room temperature in the furnace to obtain the titanium-based high-temperature wear-resistant coating.

[0012] In step S1, the sand used for sandblasting is SiO2, and the sandblasting air pressure is 0.2 - 0.4 MPa.

[0013] In step S2, the temperature of the preheating treatment is 400 - 600 °C, and the preheating time is 20 - 40 min.

[0014] The process conditions of laser cladding in step S3 refer to a laser power of 2400 - 3000 W, a scanning speed of 200 - 400 mm / min, an overlapping rate of 20 - 40%, a powder feeding rate of 10 - 15 g / min, argon as the protective gas, and a gas pressure of 0.1 - 0.3 MPa.

[0015] The conditions of stress relief annealing treatment in step S4 refer to an annealing temperature of 450 - 600 °C and a holding time of 4 - 6 h.

[0016] The present invention has the following advantages compared with the prior art: 1. The coating material of the present invention is composed of a titanium-based alloy, which has good compatibility and matching with the titanium alloy substrate, is beneficial to improving the bonding strength between the coating and the titanium alloy substrate, and the bonding strength reaches more than 800 MPa.

[0017] 2. C element is added to the coating material of the present invention. Due to the good affinity between Ti element and C element, the wear-resistant reinforcing phase TiC is synthesized in-situ by laser, which can improve the wettability and dispersion uniformity between the metal matrix phase and the wear-resistant reinforcing phase, thereby improving the interfacial bonding between the matrix phase and the wear-resistant reinforcing phase and avoiding the peeling and pulling out of the wear-resistant reinforcing phase under high-speed and heavy-load service conditions. At the same time, based on the fact that the physical property parameters such as the thermal expansion coefficient and density of TiC are close to those of the titanium-based alloy, the wear-resistant performance of the titanium-based coating is improved by using the high hardness, high modulus and good high-temperature stability of TiC, so as to meet the application requirements of low friction and wear resistance under high-speed and heavy-load conditions. And the introduction of TiC improves the coating hardness, making the Vickers hardness of the coating greater than 550 HV5.

[0018] 3. The high-temperature wear-resistant coating prepared by the present invention has a uniform and dense structure, without defects such as cracks and pores; when it is abraded against the Ni-Cr-Al / Ni-Cg abradable coating material on the inner surface of the casing under high-speed and heavy-load conditions in the laboratory, the friction coefficient of the wear-resistant coating is reduced by more than 50% compared with the titanium alloy substrate, and the wear rate is reduced by more than 2 orders of magnitude. Description of the Drawings

[0019] The following further details the specific embodiments of the present invention with reference to the drawings.

[0020] Figure 1 It is a cross-sectional morphology diagram of the high-temperature wear-resistant coating prepared in Example 1 of the present invention.

[0021] Figure 2 The bonding strength between the high-temperature wear-resistant coatings prepared in Examples 1 - 3 of the present invention and the titanium alloy substrate. Specific Embodiments

[0022] A high-temperature wear-resistant coating material for the tip of a titanium alloy blade. This coating material is made from the following powder raw materials by mass percentage (mass unit: g): 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 is Ti.

[0023] Among them: The powder raw materials Al, V, Fe, Si, C, and Ti are all powders with a purity greater than 99%.

[0024] A preparation method for a high-temperature wear-resistant coating material for the tip of a titanium alloy blade. This coating material is prepared by gas atomization: The alloying elements Al, V, Fe, Si, and Ti are melted and atomized into spherical powders with a particle size of 45 - 125 µm; then the spherical powders and C powder are ball-milled at a rotation speed of 80 - 100 r / min for 4 - 6 h and mixed evenly to obtain the product. Using a lower rotation speed ensures the integrity of the spherical powders.

[0025] A laser cladding method using the above coating material: Using TC17 titanium alloy as the blade material, which is also applicable to other titanium alloys, a titanium-based high-temperature wear-resistant coating is prepared on the tip of the TC17 titanium alloy blade by laser cladding technology using a fiber laser. During the fiber laser cladding process, the C powder and the titanium-based alloy powder undergo an in-situ reaction to generate the wear-resistant reinforcing phase TiC.

[0026] The specific method includes the following steps: S1 First, the titanium alloy blade blank is subjected to sandblasting. The sand used for sandblasting is SiO2, and the sandblasting air pressure is 0.2 - 0.4 MPa. Then it is cleaned with anhydrous ethanol and dried with compressed air to obtain the pretreated blade blank.

[0027] S2 The pretreated blade blank is placed in a muffle furnace and preheated at 400 - 600 °C 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.

[0028] S3 Using the coaxial powder feeding method, the coating material is laser-cladded at the tip of the heat-treated blade to obtain the cladding specimen. The process conditions for laser cladding refer to a laser power of 2400 - 3000 W, a scanning speed of 200 - 400 mm / min, an overlap rate of 20 - 40%, a powder feeding rate of 10 - 15 g / min, the shielding gas is argon, and the gas pressure is 0.1 - 0.3 MPa.

[0029] S4 The cladding specimen is subjected to stress relief annealing at 450 - 600 °C for 4 - 6 h to further reduce the residual stress in the coating, and then it is cooled to room temperature in the furnace to obtain the titanium-based high-temperature wear-resistant coating.

[0030] Example 1 A high-temperature wear-resistant coating was prepared on the tip of a titanium alloy blade using the laser cladding technique. The specific steps are as follows: S1 The titanium-based powder obtained by gas atomization and C powder were formulated at a mass ratio (g / g) of 99.8:0.2 and then ball-milled. The ball-milling speed was 100 r / min, and the ball-milling time was 4 h. After ball-milling, it was reserved for 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.%.

[0031] S2 The TC17 titanium alloy blade blank was sandblasted. The sand used for sandblasting was SiO2, and the sandblasting air pressure was 0.3 MPa. After sandblasting, the TC17 titanium alloy blade blank was cleaned with absolute ethanol and then dried with compressed air for standby.

[0032] S3 The cleaned TC17 titanium alloy blade blank was placed in a muffle furnace for preheating treatment. The preheating temperature was 400 °C, and the preheating time was 40 min to reduce the temperature gradient and residual stress during the laser cladding process and eliminate defects in the coating.

[0033] S4 The mixed titanium-based powder was loaded into a powder feeder, and a high-temperature wear-resistant coating was cladded on the tip of the preheated titanium alloy blade blank using a fiber laser. The cladding process: laser power 2400 W, scanning speed 200 mm / min, overlapping rate 37%, powder feeding rate 10 g / min, the shielding gas was argon, and the gas pressure was 0.1 MPa.

[0034] S5 The TC17 titanium alloy blade blank obtained after laser cladding was subjected to stress relief annealing treatment. The annealing temperature was 600 °C, the holding time was 4 h, and it was cooled to room temperature in the furnace.

[0035] The microstructure of the high-temperature wear-resistant coating prepared in Example 1 was observed as Figure 1 shown. It can be seen from Figure 1 that the coating structure is uniform, the tissue is dense, there are no obvious defects such as pores and cracks, and it shows good metallurgical bonding with the titanium alloy substrate.

[0036] Example 2 The coating material and the high-temperature wear-resistant coating were prepared according to the method of Example 1, except that the titanium-based powder and the C powder were formulated 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, overlapping rate 37%, powder feeding rate 15 g / min.

[0037] Example 3 The coating material and the high-temperature wear-resistant coating were prepared according to the method of Example 1, except that the titanium-based powder and the C powder were formulated 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, overlapping rate 40%, powder feeding rate 15 g / min.

[0038] The Vickers hardness, bonding strength and high-temperature wear resistance of the high-temperature wear-resistant coatings prepared in Examples 1 to 3 were tested according to the following method: (1) Vickers hardness The Vickers hardness of the coating surface was tested using an SVD-4052TS type Vickers hardness tester with a loading load of 5000 gf and a holding time of 10 s. The test results are listed in Table 1.

[0039] Table 1 Vickers hardness of the high-temperature wear-resistant coatings prepared in Examples 1 to 3 (2) High-temperature tribological properties Test conditions: A high-temperature wear-resistant coating was laser-cladded on the surface of TC17 titanium alloy. After the coating surface was polished flat, it was processed into a friction specimen with dimensions of Φ24×4 mm as the disc, and 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 °C, the motion form was rotational sliding, the rotational radius was 5 mm, the load was 100 N, and the rotational speed was 360 rpm. The test results are listed in Table 2.

[0040] Table 2 Tribological properties of the high-temperature wear-resistant coatings prepared in Examples 1 to 3 (3) Bonding strength A "V"-shaped groove with a depth of 3 mm and an angle of 45° was machined on the surface of a TC17 titanium alloy specimen, and then the "V"-shaped groove was filled using the laser cladding processes of Examples 1 to 3. A dumbbell-shaped specimen with a thickness of 2 mm was intercepted from the joint perpendicular to the cladding direction. After specimen machining, the cladding area was located at the middle position of the parallel length of the specimen. According to the GB / T228.1-2021 standard, a universal material testing machine was used, and the loading rate was set at 0.5 mm / min. The test force was continuously applied until the specimen broke, and the bonding strength between the coating and the substrate was obtained. Figure 2 It is the stress-strain curve of the specimen bonding strength. It can be seen that the bonding strengths between the coatings obtained by using the laser cladding processes of Examples 1 to 3 and the titanium alloy substrate are 836 MPa, 821 MPa, and 815 MPa respectively.

[0041] In summary, the high-temperature wear-resistant coating at the tip of the titanium alloy blade provided by the present invention has a dense structure, without defects such as cracks and pores; the coating has a high Vickers hardness and a high bonding strength with the titanium alloy substrate. When abraded against the abradable coating material Ni-Cr-Al / Ni-Cg on the inner surface of the casing under high-speed and heavy-load conditions, the coating exhibits excellent friction and wear performance, and can provide long-term and effective high-temperature wear-resistant protection for the tip of the titanium alloy blade.

[0042] Although the above embodiments have described the present invention in detail, they are only a part of the embodiments of the present invention, rather than all embodiments. People can also obtain other embodiments based on these embodiments without creative efforts, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A high-temperature wear-resistant coating material for the tip of a titanium alloy blade, characterized in that: The coating material is made of 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, and the balance is Ti.

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

3. The preparation method of a high-temperature wear-resistant coating material for the tip of a titanium alloy blade according to claim 1 or 2, characterized in that: The coating material is prepared by gas atomization. The 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 and C powder are ball-milled at a rotation speed of 80 - 100 r / min for 4 - 6 h and mixed evenly to obtain the product.

4. A laser cladding method using the coating material as described in claim 1 or 2, characterized in that: Using TC17 titanium alloy as the blade material, a titanium-based high-temperature wear-resistant coating is prepared on the tip of the TC17 titanium alloy blade by laser cladding technology with the coating material through a fiber laser.

5. A laser cladding method as described in claim 4, comprising the following steps: S1 The titanium alloy blade blank is first sandblasted, then cleaned with anhydrous ethanol, and dried with compressed air to obtain the pretreated blade blank. S2 The pretreated blade blank is placed in a muffle furnace for preheating treatment to obtain the heat-treated blade. S3 Using the coaxial powder feeding method, the coating material is laser-cladded on the tip of the heat-treated blade to obtain the cladding specimen. S4 The cladding specimen is subjected to stress relief annealing treatment and then cooled in the furnace to room temperature to obtain the titanium-based high-temperature wear-resistant coating.

6. The laser cladding method according to claim 5, characterized in that: In step S1, the sand used for sandblasting is SiO2, and the sandblasting air pressure is 0.2 - 0.4 MPa.

7. The laser cladding method according to claim 5, characterized in that: In step S2, the temperature of the preheating treatment is 400 - 600 °C, and the preheating time is 20 - 40 min.

8. The laser cladding method according to claim 5, characterized in that: In step S3, the process conditions of laser cladding refer to a laser power of 2400 - 3000 W, a scanning speed of 200 - 400 mm / min, an overlap rate of 20 - 40%, a powder feeding rate of 10 - 15 g / min, the shielding gas is argon, and the gas pressure is 0.1 - 0.3 MPa.

9. A laser cladding method according to claim 5, characterized in that: In step S4, the conditions of the stress relief annealing treatment refer to an annealing temperature of 450 - 600 °C and a holding time of 4 - 6 h.

Images