Gamma-TiAl material turbine blade sawtooth crown wear-resistant coating plating method

Abstract

The invention relates to the technical field of metal material plating, in particular to a gamma-TiAl material turbine blade sawtooth crown wear-resistant coating plating method which comprises a multi-station special plating device and an aviation kerosene and oxygen mixed fuel hypersonic flame spraying process. The plating devices are arranged in a linear mode and an annular mode, one-time clamping plating of 15 blades and one-time clamping plating of 30 blades are achieved respectively, and efficiency is remarkably improved. According to the device, accurate positioning and non-spraying area protection are achieved through the positioning block, the pressing plate assembly and other structures. The Co-Mo-Cr-Si wear-resistant coating is plated by adopting a high velocity oxy-fuel spraying process, so that the heat input is low, the coating is compact, and the bonding strength is high; the surface roughness of the coating reaches Ralt through subsequent grinding; and 0.8 [mu] m. The problems of high heat input and low construction efficiency in the prior art are solved, and the requirements of the aero-engine for high precision and high reliability are met.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal material plating, and particularly relates to a method for plating a wear-resistant coating on the serrated crown of a γ-TiAl material turbine blade. Background Art

[0002] As a core component, the turbine blade of an aeroengine works in a harsh environment of high temperature, high pressure, high-speed strong turbulence and multi-source large-load alternating action for a long time, and its performance directly affects the reliability and efficiency of the engine. The serrated crown, also known as the "Z"-shaped crown, is an important structure of the turbine blade. The working surface adopts a tightness design, which can reduce the air leakage from the blade basin to the blade back at the tip, reduce the underflow loss of the turbine component, and improve the turbine efficiency through the close fit of the contact surface; after the adjacent crowns are pressed tightly, the twist and bending deformation of the blade can be reduced, the rigidity of the blade can be enhanced, and the vibration frequency of the blade can be increased; the friction between adjacent crowns can absorb the energy generated by the blade vibration, playing a role in shock absorption and suppressing vibration. However, during service, the contact surface of the serrated crown is prone to oxidation, wear and even fretting fatigue due to frequent friction, thermal shock and fretting wear, which may lead to crack initiation or propagation, seriously affecting the service life and safety of the blade. The γ-TiAl-based material is considered an ideal choice for the new generation of high-temperature structural materials due to its low density (about 4.0 g / cm 3 )、high elastic modulus, good high-temperature strength and creep resistance. Replacing nickel-based superalloys with it can significantly reduce the weight of components, improve the thrust-to-weight ratio of the engine, and reduce fuel consumption and emissions. However, the γ-TiAl material has a relatively low hardness (HV300-500), weak wear resistance and fretting wear resistance, is prone to oxidation at high temperatures, has a large brittleness, and surface damage may lead to catastrophic failure. Therefore, plating a wear-resistant coating on the contact surface of the serrated crown has become a key measure to extend the service life and improve the reliability of γ-TiAl material turbine blades.

[0003] At present, the plating methods for wear-resistant coatings on the contact surface of serrated crowns mainly include microbeam argon arc surfacing, vacuum high-temperature brazing and laser cladding, etc. However, these methods have many deficiencies. Microbeam argon arc surfacing is prone to cause deformation or oxidation of the TiAl matrix due to the high arc temperature and large heat input, resulting in welding defects and too long heat affected zone, seriously restricting the safe use of the blade; at the same time, the process is complex, requires inert gas protection, and has a high cost. The vacuum brazing layer is prone to softening or oxidation at high temperatures, with insufficient long-term reliability, and the wettability between the brazing filler metal and the hard wear-resistant layer material is poor, making it difficult to form a high-performance coating. Although laser cladding is metallurgical bonding, its high heat input is prone to cause coating cracking during the rapid cooling process, and tempering treatment is required to eliminate stress.

[0004] The coated area on the contact surface of the blade serrated crown is small, and the high-temperature and high-speed flame flow erosion is large during supersonic flame spraying. How to effectively protect the non-sprayed area from overspray is the key to using the supersonic flame spraying process. High-temperature pressure-sensitive tape is a commonly used protection tool, but it is extremely easy to burn at high temperature during the supersonic flame spraying process, resulting in protection failure. The non-coated area of the blade is protected with high-temperature resistant mastic, and only the contact surface area of the serrated crown is exposed, and then it is placed in a drying oven at 100 °C and heated for 30 minutes for curing. The spraying test results show that the cured mastic cannot resist the high-temperature and high-speed flame flow erosion, the consumption speed is too fast, and the deformation is serious, so it cannot effectively protect the non-coated area. The shaped rubber tooling produces obvious deformation after only 5 times of supersonic flame spraying flame flow erosion.

[0005] In addition, the existing coating technologies generally have problems such as high heat input, low construction efficiency, and poor adaptability to complex shapes, and cannot meet the high-efficiency production requirements of the wear-resistant coating for the serrated crown of γ-TiAl material turbine blades. Therefore, developing a wear-resistant coating plating method suitable for the serrated crown of γ-TiAl material turbine blades, which can effectively reduce the heat input, improve the coating quality and production efficiency, has become an urgent technical problem to be solved. Summary of the Invention

[0006] Aiming at the defects of the existing wear-resistant coating plating technology for the serrated crown of γ-TiAl material turbine blades, such as high heat input, low construction efficiency, and poor adaptability to complex shapes, the present invention proposes a wear-resistant coating plating method for the serrated crown of γ-TiAl material turbine blades, and designs a special multi-station plating device, aiming to achieve efficient and batch production of coatings, while ensuring that the coatings are dense, uniform and well combined with the substrate, providing technical support for improving the service performance of aero-engine turbine blades.

[0007] The technical solution of the present invention is as follows: A wear-resistant coating plating method for the serrated crown of γ-TiAl material turbine blades, comprising the following steps: Step 1, perform surface pretreatment on the area to be coated on the serrated crown of the turbine blade to make its surface roughness Ra 2.0~3.8μm; Step 2, use a multi-station special plating device to clamp and position the blade, and protect the non-sprayed area; Step 3, adopt an aviation kerosene-oxygen mixed fuel supersonic flame spraying process to spray a cobalt-molybdenum-chromium-silicon wear-resistant coating with a thickness of 0.30~0.40mm on the blade surface. During the spraying process, blow air to cool the blade and monitor the blade temperature in real time to ensure that it does not exceed 204 °C; Step 4, perform grinding treatment on the sprayed coating to make the surface of the coating show a uniform metallic luster; Among them, the composition of the cobalt-molybdenum-chromium-silicon wear-resistant coating powder includes, by weight percentage: Mo: 27.0 - 30.0 wt%, Cr: 16.5 - 18.5 wt%, Si: 3.0 wt% - 3.8 wt%, and the balance is Co. And the powder particle size distribution range needs to meet: 100.0 wt% of the powder with a particle size below 75 μm, no more than 8.0 wt% of the powder with a particle size of 45 μm - 75 μm, not less than 92.0 wt% of the powder with a particle size below 45 μm, 55.0 - 70.0 wt% of the powder with a particle size of 20 μm - 45 μm, and no more than 8.0 wt% of the powder with a particle size below 10 μm.

[0008] Further, for the above-mentioned method for plating a wear-resistant coating on the serrated crown of a γ-TiAl material turbine blade, in step 1, the surface pretreatment process is to use a pressure-fed sandblasting gun to perform sandblasting on the area to be plated. The sand type is 60# white fused alumina sand, the sandblasting pressure is 0.25 - 0.35 MPa, the sandblasting distance is 140 - 180 mm, the sandblasting angle is 55° - 85°, the moving speed of the sandblasting gun is 5 mm / s, and the diameter of the sandblasting gun nozzle is 7.0 - 8.5 mm; spraying is carried out within 2 hours after sandblasting.

[0009] Further, for the above-mentioned method for plating a wear-resistant coating on the serrated crown of a γ-TiAl material turbine blade, in step 3, before spraying, the spraying powder is dried at a temperature in the range of 66 - 82 °C for at least 1 hour and stirred for 10 - 15 minutes before use. After detecting the powder feeding rate and nozzle status, spraying is carried out.

[0010] Further, for the above-mentioned method for plating a wear-resistant coating on the serrated crown of a γ-TiAl material turbine blade, in step 3, a supersonic flame spraying device based on a mixture of aviation kerosene and oxygen is used for spraying. The spraying process parameters include: the barrel length is 101.6 mm, the nozzle diameter is 10.5 - 11.5 mm, the kerosene flow rate is 21 - 25 L / h, the oxygen flow rate is 850 - 930 NLPM, the spraying distance is 350 - 380 mm, the powder feeding rate is 53 - 63 g / min, the gun moving speed is 350 - 450 mm / s, the gun angle is 40° - 60°, the carrier gas is argon, and the carrier gas flow rate is 4.5 - 5.5 NLPM.

[0011] Further, for the above-mentioned method for plating a wear-resistant coating on the serrated crown of a γ-TiAl material turbine blade, the air-cooling process parameters include: the cooling air pressure is 0.3 - 0.5 MPa, the cooling air distance is 290 - 380 mm, the cooling air angle is 70° - 90°, and the diameter of the cooling air pipe is 7.0 - 9.0 mm; an infrared thermometer is used to monitor the part temperature. When the part temperature exceeds 204 °C, spraying is interrupted and the part is cooled.

[0012] Further, for the above-mentioned method for plating a wear-resistant coating on the serrated crown of a γ-TiAl material turbine blade, a single-sided creep-feed grinding machine is used to grind the serrated crown. The number of feed passes is 5 times, and the machining removal amounts are 0.03 mm, 0.02 mm, 0.02 mm, 0.01 mm, and 0.01 mm respectively. The linear velocity of the grinding wheel is 25 m / s, and finally the surface roughness Ra of the coating is less than 0.8 μm.

[0013] Further, for the above-mentioned method for plating a wear-resistant coating on the serrated crown of a γ-TiAl material turbine blade, the multi-station special plating device can simultaneously plate the wear-resistant coatings on the basin side and back side of 15 - 30 blades in one clamping, including a plating device one with a linear arrangement clamping method and a plating device two with a circular arrangement clamping method.

[0014] Further, for the above-mentioned method for plating a wear-resistant coating on the serrated crown of a γ-TiAl material turbine blade, the plating device one includes a support assembly, positioning blocks, a pressing plate assembly, a cap assembly, a baffle and a stop block, a guard plate, a plate buckle, and a flange bolt; The support assembly is used to support the entire device, including an upper support plate and a base connected by a steel pipe. The upper support plate is used to install the positioning blocks. The base is provided with a rectangular groove, threaded holes for positioning the pressing plate assembly, and threaded holes for installing the plate buckle; The positioning blocks are used to position the blades, including positioning blocks for the outer side of the whole row of parts and positioning blocks for the remaining workstations, and are positioned through the flow channel profile and the side surface of the blade crown; The pressing plate assembly includes a left pressing plate assembly, a middle pressing plate assembly, and a right pressing plate assembly, all of which are welded assemblies and are composed of a positioning seat, a support seat, a beam, and a protection plate. The positioning seat is positioned through the flow channel profile and the side surface of the blade crown. The upper end of the support seat is connected to the positioning seat, and the lower end is designed as a T-shaped structure and is positioned in cooperation with the rectangular groove, the flange bolt, and the plate buckle on the base in the support assembly; the protection plate is used to protect the non-sprayed area; The device realizes the sealing around the device through the baffle on the base of the support assembly and the protection plates of the left and right pressing plate assemblies, wherein the baffles on the left and right sides of the base are fixed on the base through the stop blocks; The cap assembly is used for pressing the parts and protecting the non-sprayed area, is positioned with the support assembly through the cylindrical pins on both sides, and is connected to the support assembly through the threaded hole in the middle. The guard plate is located in the gap of the cap assembly and is used to protect other non-sprayed areas that cannot be covered by the cap assembly.

[0015] Further, for the above-mentioned method for plating a wear-resistant coating on the serrated crown of a γ-TiAl material turbine blade, the plating device two includes a device base, positioning blocks, a pressing block, and a positioning plug; The device base is a two-layer ring-shaped part made of aluminum alloy, which is divided into an upper disc and a lower chassis. Inner and outer baffles are provided on the inner and outer sides of the base. The upper disc is designed with evenly distributed rectangular stepped grooves and threaded holes for the positioning and installation of positioning block c, and the spraying surfaces of the blade basin and back wear-resistant blocks are tangent to the circumference; the lower chassis is positioned and connected to the spraying equipment, and the upper disc and the lower chassis are connected into one body by multiple aluminum alloy struts; The positioning block c is positioned by the runner profile and the side surface of the shroud of the blade tip, and is a quick-release and independent structure; The pressing block is pressed by the top of the shroud of the blade tip, and is a quick-release and independent structure; The positioning plug is located at the center of the device and is used for the positioning of the device and the workbench.

[0016] Advantages and beneficial effects of the present invention: Through the supersonic flame spraying process combined with a multi-station special plating device, the heat input during the spraying process is significantly reduced, avoiding the oxidation and deformation problems of γ-TiAl materials caused by high temperature. At the same time, the coating density and bonding strength are improved. The multi-station special plating device can produce 15 to 30 pieces of blade basin and back wear-resistant coatings in one clamping, greatly improving the production efficiency and meeting the requirements of batch production. In addition, the grinding process after spraying further optimizes the surface quality of the coating, making its roughness reach Ra less than 0.8μm, meeting the requirements of aero-engines for high precision and high reliability. Description of the drawings

[0017] Figure 1 It is a schematic diagram of the area of the wear-resistant coating to be sprayed on the serrated crown of the γ-TiAl material turbine blade, where (a) is the spraying area in the blade basin direction and (b) is the spraying area in the blade back direction; Figure 2 It is a schematic diagram of the spraying area when using plating device one, where (a) is the spraying area in the blade basin direction and (b) is the spraying area in the blade back direction; Figure 3 It is a schematic diagram of the spraying area when using plating device two, where (a) is the spraying area in the blade basin direction and (b) is the spraying area in the blade back direction; Figure 4 It is a three-dimensional schematic diagram of plating device one; Figure 5 It is a front view of plating device one; Figure 6 It is a top view of plating device one; Figure 7 For Figure 5 Schematic diagram of A-A section; Figure 8 It is a three-dimensional schematic diagram of the support assembly of plating device one; Figure 9Schematic diagram a of a positioning block for the outer side of a row of parts in a plating device; Figure 10 Schematic diagram b of a positioning block for the remaining workstations in a plating device; Figure 11 Schematic diagrams of the inner and outer sides of the left pressing plate assembly of a plating device, where (a) is the inner side schematic diagram and (b) is the outer side schematic diagram; Figure 12 Schematic diagrams of the inner and outer sides of the middle pressing plate assembly of a plating device, where (a) is the inner side schematic diagram and (b) is the outer side schematic diagram; Figure 13 Schematic diagrams of the inner and outer sides of the right pressing plate assembly of a plating device, where (a) is the inner side schematic diagram and (b) is the outer side schematic diagram; Figure 14 Schematic diagram of the cap assembly of a plating device; Figure 15 Front view of plating device two; Figure 16 Three-dimensional schematic diagram of the base of plating device two; Figure 17 Schematic diagram c of a positioning block for plating device two; Figure 18 Schematic diagram of the pressing block for plating device two; Figure 19 Sectional tissue splicing diagram of the coating simulation part in Embodiment 2 of the present invention; Figure 20 Microscopic structure diagram of the coating after spraying in the embodiment of the present invention, where (a) is for Embodiment 1, (b) is for Embodiment 3, (c) is for Embodiment 4, and (d) is for Embodiment 5; In the figure, 1 - support assembly; 101 - upper support plate; 102 - base; 2 - positioning block a, 3 - positioning block b; 4 - left pressing plate assembly; 401 - positioning seat; 402 - support seat; 403 - beam; 404 - protection plate; 5 - middle pressing plate assembly; 6 - right pressing plate assembly; 7 - cap assembly, 8 - baffle; 9 - stop block, 10 - guard plate, 11 - plate buckle; 12 - flange bolt; base 13; 1301 - upper layer disc; 1302 - lower layer chassis; 1303 - inner baffle; 1304 - outer baffle; 1305 - pillar; 14 - positioning block c; 15 - pressing block; 16 - positioning plug; 17 - blade basin side; 18 - blade back side. Detailed implementation manners

[0018] In a specific embodiment, the present invention provides a method for plating a wear-resistant coating on the serrated crown of a γ-TiAl material turbine blade. Through the design and application of a multi-station special plating device and the specific implementation of the supersonic flame spraying process, efficient and high-quality plating of the wear-resistant coating for machining both the concave and convex sides of all blades is achieved in one clamping. The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0019] As Figure 1 shown, it is a schematic diagram of the area of the wear-resistant coating to be sprayed on the serrated crown of the γ-TiAl material turbine blade of the present invention. When implementing the present invention, it is first necessary to prepare a multi-station special plating device. This device has two structural forms: plating device one with a linear arrangement clamping method and plating device two with a circular arrangement clamping method. The spraying areas when using plating devices one and two are as Figure 2 , Figure 3 shown, and spraying is carried out on the concave side 17 and the convex side 18 of the blade.

[0020] As Figure 4 - 14 , plating device one can be used for one clamping of 15 blades, and includes a support assembly 1, positioning blocks, a pressing plate assembly, a cap assembly 7, a baffle 8, a stop block 9, a guard plate 10, a plate buckle 11, and a flange bolt 12; The support assembly 1 is used to support the entire device, and includes an upper support plate 101 and a base 102 connected by a steel pipe. The upper support plate 101 is used to install the positioning blocks, and the base 102 is provided with a rectangular groove, threaded holes for positioning the pressing plate assembly, and threaded holes for installing the plate buckle; The positioning blocks are used to position the blades, and include positioning block a2 for the outer side of the whole row of parts and positioning block b3 for the remaining workstations, and are positioned through the runner profile and side surface of the blade crown; The pressing plate assembly includes a left pressing plate assembly 4, a middle pressing plate assembly 5, and a right pressing plate assembly 6, all of which are welded assemblies and are composed of a positioning seat 401, a support seat 402, a beam 403, and a protection plate 404. The positioning seat 401 is positioned by the runner profile and side surface of the blade crown. The upper end of the support seat 402 is connected to the positioning seat 401, and the lower end is designed as a T-shaped structure and is cooperatively positioned with the rectangular groove, flange bolt 12, and plate buckle 11 on the base 102 of the support assembly 1; the protection plate 404 is used to protect the non-spraying area; The device realizes the sealing around the device through the baffle 8 on the base 102 of the support assembly 1 and the protection plates 404 of the left and right pressing plate assemblies, wherein the baffles 8 on the left and right sides of the base are fixed on the base by the stop blocks 9; The cap assembly 7 is used for compressing parts and protecting non-spray areas. It is positioned with the support assembly 1 through cylindrical pins on both sides and connected to the support assembly 1 through threaded holes in the middle. The guard plate 10 is located in the gap of the cap assembly 7 and is used to protect other non-spray areas that cannot be covered by the cap assembly 7.

[0021] As Figure 15 - 18 shown, the second plating device includes a device base 13, a positioning block c14, a pressing block 15, and a positioning plug 16; The device base 13 is a two-layer annular part made of aluminum alloy material, which is divided into an upper disk 1301 and a lower chassis 1302. Inner baffles 1303 and outer baffles 1304 are provided on the inner and outer sides of the base. The upper disk 1301 is designed with 30 equally distributed rectangular step grooves and threaded holes for the positioning and installation of the positioning block c14, and the spraying surfaces of the blade basin and the back wear-resistant block are tangent to the circumference; the lower chassis is positioned and connected to the spraying equipment, and the upper disk and the lower chassis are connected into one body through a plurality of aluminum alloy struts 1305; the positioning block c14 is positioned through the blade crown's shroud runner profile and the shroud side surface, and it is a quick-release and independent structure; The pressing block 15 is pressed through the top of the blade crown and is a quick-release and independent structure; The positioning plug 16 is located at the center of the device and is used for the positioning of the device and the workbench.

[0022] After the plating device is prepared, it enters the working stage, which specifically includes the following steps: Step 1: Perform surface pretreatment on the area to be plated of the turbine blade serrated crown. Use a pressure-fed sandblasting gun to perform sandblasting on the area to be plated. The sand type is 60# white fused alumina sand, the sandblasting pressure is 0.25 - 0.35 MPa, the sandblasting distance is 140 - 180 mm, the sandblasting angle is 55° - 85°, the moving speed of the sandblasting gun is 5 mm / s, and the diameter of the sandblasting gun nozzle is 7.0 - 8.5 mm; perform spraying within 2 hours after sandblasting to make the surface roughness Ra 2.0 - 3.8 μm; Step 2: Use a multi-station special plating device to clamp and position the blade and protect the non-spray area; Step 3: Adopt the aviation kerosene oxygen mixed fuel supersonic flame spraying process to spray a cobalt-molybdenum-chromium-silicon wear-resistant coating with a thickness of 0.30 - 0.40 mm on the blade surface. During the spraying process, blow air to cool the blade and monitor the blade temperature in real time to ensure that it does not exceed 204°C; Before spraying, dry the spraying powder within the temperature range of 66 - 82°C for at least 1 hour and stir it for 10 - 15 minutes before use. After detecting the powder feeding rate and the nozzle state, perform spraying; The spraying process parameters include: the barrel length is 101.6 mm, the nozzle diameter is 10.5 - 11.5 mm, the kerosene flow rate is 21 - 25 L / h, the oxygen flow rate is 850 - 930 NLPM, the spraying distance is 350 - 380 mm, the powder feeding rate is 53 - 63 g / min, the gun moving speed is 350 - 450 mm / s, the gun angle is 40° - 60°, the carrier gas is argon, and the carrier gas flow rate is 4.5 - 5.5 NLPM; The air-blowing cooling process parameters include: the cooling air pressure is 0.3 - 0.5 MPa, the cooling air distance is 290 - 380 mm, the cooling air angle is 70° - 90°, and the cooling air pipe diameter is 7.0 - 9.0 mm; an infrared thermometer is used to monitor the temperature of the part, and when the part temperature exceeds 204 °C, the spraying is interrupted and the part is cooled; Step 4: Grind the sprayed coating. Use a single-sided creep-feed grinding machine to grind the serrated crown. The number of feed passes is 5 times, and the machining removal amounts are 0.03 mm, 0.02 mm, 0.02 mm, 0.01 mm, and 0.01 mm respectively. The grinding wheel linear speed is 25 m / s, so that the coating surface shows a uniform metallic luster and finally the surface roughness Ra of the coating is less than 0.8 μm; Among them, the composition of the cobalt-molybdenum-chromium-silicon wear-resistant coating powder by weight percentage includes Mo: 27.0 - 30.0 wt%, Cr: 16.5 - 18.5 wt%, Si: 3.0 wt% - 3.8 wt%, and the balance is Co. And the powder particle size distribution range needs to meet: the powder with a particle size below 75 μm is 100.0 wt%, the powder with a particle size of 45 μm - 75 μm is not more than 8.0 wt%, the powder with a particle size below 45 μm is not less than 92.0 wt%, the powder with a particle size of 20 μm - 45 μm is 55.0 - 70.0 wt%, and the powder with a particle size below 10 μm is not more than 8.0 wt%.

[0023] Next, the plating process of the present invention will be further described in detail in combination with the embodiments.

[0024] Example 1

[0025] A method for plating a wear-resistant coating on the serrated crown of a γ-TiAl material turbine blade in this embodiment includes the following steps: Step 1: Perform surface pretreatment on the area to be plated of the serrated crown of the turbine blade. Use a pressure-fed sandblasting gun to perform sandblasting on the area to be plated. The sand type is 60# white fused alumina sand, the sandblasting pressure is 0.25 MPa, the sandblasting distance is 140 mm, the sandblasting angle is 55°, the moving speed of the sandblasting gun is 5 mm / s, and the diameter of the sandblasting gun nozzle is 7.0 mm; spraying is carried out within 2 hours after sandblasting to make its surface roughness Ra 2.0 μm; Step 2: Use the plating device one to clamp and position the blade and protect the non-spraying area; Step 3: Use the aviation kerosene-oxygen mixed fuel supersonic flame spraying process to spray a cobalt-molybdenum-chromium-silicon wear-resistant coating with a thickness of 0.30 mm on the blade surface. During the spraying process, blow air to cool the blade and monitor the blade temperature in real time to ensure that it does not exceed 204°C; Before spraying, dry the spraying powder at a temperature of 66°C for 1 hour and stir it for 10 minutes before use. After detecting the powder feeding rate and nozzle status, carry out spraying; The spraying process parameters include: the barrel length is 101.6 mm, the nozzle diameter is 10.5 mm, the kerosene flow rate is 21 L / h, the oxygen flow rate is 850 NLPM, the spraying distance is 350 mm, the powder feeding rate is 53 g / min, the gun moving speed is 350 mm / s, the gun angle is 40°, the carrier gas is argon, and the carrier gas flow rate is 4.5 - 5.5 NLPM; The blow air cooling process parameters include: the cooling air pressure is 0.3 MPa, the cooling air distance is 290 mm, the cooling air angle is 70°, and the cooling air pipe diameter is 7.0 mm; Use an infrared thermometer to monitor the part temperature. When the part temperature exceeds 204°C, interrupt spraying and cool the part; Step 4: Carry out grinding processing on the sprayed coating. Use a single-sided creep-feed grinding machine to grind the serrated crown. The number of feed passes is 5 times, and the machining removal amounts are 0.03 mm, 0.02 mm, 0.02 mm, 0.01 mm, and 0.01 mm respectively. The grinding wheel linear speed is 25 m / s, so that the coating surface shows a uniform metallic luster and finally the surface roughness Ra of the coating is 0.7 μm; Among them, the composition of the cobalt-molybdenum-chromium-silicon wear-resistant coating powder by weight percentage includes Mo: 27.0 wt%, Cr: 16.5 wt%, Si: 3.0 wt%, and the balance is Co. And the powder particle size distribution range needs to meet: 100.0 wt% of the powder with a particle size below 75 μm, 8.0 wt% of the powder with a particle size of 45 - 75 μm, 92.0 wt% of the powder with a particle size below 45 μm, 55.0 wt% of the powder with a particle size of 20 - 45 μm, and 8.0 wt% of the powder with a particle size below 10 μm.

[0026] Example 2

[0027] A method for plating a wear-resistant coating on the serrated crown of a γ-TiAl material turbine blade in this example includes the following steps: Step 1: Perform surface pretreatment on the area to be plated on the serrated crown of the turbine blade. Use a pressure-fed sandblasting gun to sandblast the area to be plated. The sand type is 60# white fused alumina sand, the sandblasting pressure is 0.35 MPa, the sandblasting distance is 180 mm, the sandblasting angle is 85°, the moving speed of the sandblasting gun is 5 mm / s, and the sandblasting gun nozzle diameter is 8.5 mm; Carry out spraying within 2 hours after sandblasting to make its surface roughness Ra 3.8 μm; Step 2: Clamp and position the blade using Coating Device 2 and protect the non-spraying areas. Step 3: Apply a 0.40-mm-thick cobalt-molybdenum-chromium-silicon wear-resistant coating on the blade surface using the supersonic flame spraying process with aviation kerosene and oxygen mixed fuel. During the spraying process, blow air to cool the blade and monitor the blade temperature in real time to ensure it does not exceed 204°C. Before spraying, dry the spraying powder at 82°C for 1 hour and stir it for 15 minutes before use. After detecting the powder feeding rate and nozzle status, carry out spraying. The spraying process parameters include: barrel length of 101.6 mm, nozzle diameter of 11.5 mm, kerosene flow rate of 25 L / h, oxygen flow rate of 930 NLPM, spraying distance of 380 mm, powder feeding rate of 63 g / min, gun moving speed of 450 mm / s, gun angle of 60°, carrier gas being argon, and carrier gas flow rate of 5.5 NLPM. The blow air cooling process parameters include: cooling air pressure of 0.5 MPa, cooling air distance of 380 mm, cooling air angle of 90°, and cooling air pipe diameter of 9.0 mm. Use an infrared thermometer to monitor the part temperature. When the part temperature exceeds 204°C, interrupt spraying and cool the part. Step 4: Conduct grinding processing on the sprayed coating. Use a single-sided creep-feed grinding machine to grind the serrated crown. The number of feed passes is 5 times, and the machining removal amounts are 0.03 mm, 0.02 mm, 0.02 mm, 0.01 mm, and 0.01 mm respectively. The grinding wheel linear speed is 25 m / s, making the coating surface show a uniform metallic luster and finally making the surface roughness Ra of the coating less than 0.8 μm. The composition of the cobalt-molybdenum-chromium-silicon wear-resistant coating powder by weight percentage includes Mo: 30.0 wt%, Cr: 18.5 wt%, Si: 3.8 wt%, and the balance is Co. And the powder particle size distribution range needs to meet: 100.0 wt% of the powder with a particle size below 75 μm, 6.0 wt% of the powder with a particle size of 45 - 75 μm, 94.0 wt% of the powder with a particle size below 45 μm, 70.0 wt% of the powder with a particle size of 20 - 45 μm, and 5.0 wt% of the powder with a particle size below 10 μm.

[0028] Cut the simulated part after spraying in Example 2, make a metallographic specimen to observe the spraying effect. As Figure 19 shown, observe the cross-section of the simulated part under a microscope at 200 times magnification. The coating structure is good, the coating binds well with the substrate, and the coating completely covers the wear-resistant block spraying area, which can meet the service requirements of the blade.

[0029] Example 3

[0030] The difference between this embodiment and Embodiment 1 is that in the spraying process parameters, the kerosene flow rate is 24 / h.

[0031] Embodiment 4

[0032] The difference between this embodiment and Embodiment 1 is that in the spraying process parameters, the oxygen flow rate is 890 NLPM.

[0033] Embodiment 5

[0034] The difference between this embodiment and Embodiment 1 is that in the spraying process parameters, the spraying distance is 380 mm.

[0035] As Figure 20 shown, the microstructures of the coatings after spraying in Embodiments 1, 3, 4, and 5 were examined. The coating structures are uniform and complete, without delamination, transverse cracks, and interface separation. The pores and oxides in the coatings are evenly distributed.

[0036] By comparing the four groups of microstructures, it can be found that: When the kerosene flow rate increases, the porosity of the coating structure decreases and the oxides decrease; When the oxygen flow rate decreases, the porosity of the coating structure increases and the oxides decrease; When the spraying distance increases, the porosity of the coating structure increases and the oxides increase; The results of the tensile bonding strength, surface Rockwell hardness, and microhardness of the coatings after spraying in Embodiments 1, 3, 4, and 5 are compared as shown in Table 1: Table 1 Comparison of the results of the tensile bonding strength, surface Rockwell hardness, and microhardness of the coatings Example Average tensile bond strength MPa Superficial Rockwell hardness HR15N Microhardness HV300g 1 60.3 89.1 741 3 58.5 89.8 732 4 63.2 88.3 687 5 59.1 87.2 626 To meet the demanding service conditions of turbine blades, the average value of the tensile bonding strength of this coating should be not less than 41 MPa, and the single value should be not less than 38 MPa; the average value of the surface Rockwell hardness should be not less than 87 HR15N, and the single value should be not less than 85 HR15N; under a 300 g load, the average value of the microhardness should be not less than 575 HV, and the single value should not be lower than 500 HV. The coating properties sprayed in the above embodiments all meet the requirements.

Claims

1. A method for plating a wear-resistant coating on a serrated crown of a γ-TiAl material turbine blade, characterized in that, It includes the following steps: Step 1: Pretreat the surface of the area to be coated on the serrated crown of the turbine blade to make its surface roughness Ra 2.0 - 3.8 μm; Step 2: Clamp and position the blade using a multi-station special coating device and protect the non-spraying area; Step 3: Spray a cobalt-molybdenum-chromium-silicon wear-resistant coating with a thickness of 0.30 - 0.40 mm on the blade surface using an aviation kerosene-oxygen mixed fuel supersonic flame spraying process. During the spraying process, blow air to cool the blade and monitor the blade temperature in real time to ensure that it does not exceed 204°C; Step 4: Grind and process the sprayed coating to make the surface of the coating present a uniform metallic luster; Among them, the composition of the cobalt-molybdenum-chromium-silicon wear-resistant coating powder by weight percentage includes Mo: 27.0 - 30.0 wt%, Cr: 16.5 - 18.5 wt%, Si: 3.0 wt% - 3.8 wt%, and the balance is Co. And the powder particle size distribution range needs to meet: 100.0 wt% of the powder with a particle size below 75 μm, no more than 8.0 wt% of the powder with a particle size of 45 - 75 μm, not less than 92.0 wt% of the powder with a particle size below 45 μm, 55.0 - 70.0 wt% of the powder with a particle size of 20 - 45 μm, and no more than 8.0 wt% of the powder with a particle size below 10 μm.

2. A method for plating a wear-resistant coating on the serrated crown of a γ-TiAl material turbine blade according to claim 1, characterized in that, The surface pretreatment process in Step 1 is to perform sandblasting on the area to be coated using a pressure-fed sandblasting gun. The sand type is 60# white fused alumina sand, the sandblasting pressure is 0.25 - 0.35 MPa, the sandblasting distance is 140 - 180 mm, the sandblasting angle is 55° - 85°, the moving speed of the sandblasting gun is 5 mm / s, and the diameter of the sandblasting gun nozzle is 7.0 - 8.5 mm; Spraying is carried out within 2 hours after sandblasting.

3. A method for plating a wear-resistant coating on the serrated crown of a γ-TiAl material turbine blade according to claim 1, characterized in that, Before spraying in Step 3, dry the spraying powder within the temperature range of 66 - 82°C for at least 1 hour and stir for 10 - 15 minutes before use. After detecting the powder feeding rate and nozzle status, perform spraying.

4. A method for plating a wear-resistant coating on the serrated crown of a γ-TiAl material turbine blade according to claim 3, characterized in that, Step 3 uses a supersonic flame spraying device based on aviation kerosene-oxygen mixed fuel for spraying. The spraying process parameters include: the barrel length is 101.6 mm, the nozzle diameter is 10.5 - 11.5 mm, the kerosene flow rate is 21 - 25 L / h, the oxygen flow rate is 850 - 930 NLPM, the spraying distance is 350 - 380 mm, the powder feeding rate is 53 - 63 g / min, the gun moving speed is 350 - 450 mm / s, the gun angle is 40° - 60°, the carrier gas is argon, and the carrier gas flow rate is 4.5 - 5.5 NLPM.

5. A method for plating a wear-resistant coating on the serrated crown of a γ-TiAl material turbine blade according to claim 4, characterized in that, The process parameters of blowing air for cooling include: the cooling air pressure is 0.3 - 0.5 MPa, the cooling air distance is 290 - 380 mm, the cooling air angle is 70° - 90°, and the diameter of the cooling air pipe is 7.0 - 9.0 mm; Use an infrared thermometer to monitor the temperature of the part. When the part temperature exceeds 204°C, interrupt spraying and cool the part.

6. A method for plating a wear-resistant coating on the serrated crown of a γ-TiAl material turbine blade according to claim 1, characterized in that, The serrated crown is ground by a single-sided creep-feed grinding machine with 5 passes of feed. The machining removal amounts are 0.03 mm, 0.02 mm, 0.02 mm, 0.01 mm, and 0.01 mm respectively. The grinding wheel linear speed is 25 m / s, and finally the surface roughness Ra of the coating is less than 0.8 μm.

7. A method for plating a wear-resistant coating on the serrated crown of a γ-TiAl material turbine blade according to claim 1, characterized in that, The multi-station special plating device can simultaneously plate the wear-resistant coatings on the pressure side and suction side of 15 - 30 blades in one clamping, including plating device one with a linear arrangement clamping method and plating device two with an annular arrangement clamping method.

8. A method for plating a wear-resistant coating on the serrated crown of a γ-TiAl material turbine blade according to claim 7, characterized in that, Plating device one includes a support assembly, positioning blocks, pressing plate assemblies, cap assemblies, baffles and stoppers, guard plates, plate fasteners, and flange bolts. The support assembly is used to support the whole device, including an upper support plate and a base connected by a steel pipe. The upper support plate is used to install the positioning blocks. The base is provided with a rectangular groove, threaded holes for positioning the pressing plate assemblies, and threaded holes for installing the plate fasteners. The positioning blocks are used to position the blades, including positioning block a for the outer side of the whole row of parts and positioning block b for the remaining workstations, and are positioned through the runner profile and side surface of the blade crown. The pressing plate assemblies include a left pressing plate assembly, a middle pressing plate assembly, and a right pressing plate assembly, all of which are welded assemblies and are composed of a positioning seat, a support seat, a beam, and a protection plate. The positioning seat is positioned through the runner profile and side surface of the blade crown. The upper end of the support seat is connected to the positioning seat, and the lower end is designed as a T-shaped structure and is positioned in cooperation with the rectangular groove, flange bolts, and plate fasteners on the base in the support assembly. The protection plate is used to protect the non-sprayed area. The device realizes the sealing around the device through the baffles on the base of the support assembly and the protection plates of the left and right pressing plate assemblies. Among them, the baffles on the left and right sides of the base are fixed on the base through stoppers. The cap assembly is used for pressing the parts and protecting the non-sprayed area. It is positioned with the support assembly through the cylindrical pins on both sides and is connected to the support assembly through the threaded hole in the middle. The guard plate is located in the gap of the cap assembly and is used to protect other non-sprayed areas that cannot be covered by the cap assembly.

9. A method for plating a wear-resistant coating on the serrated crown of a γ-TiAl material turbine blade according to claim 7, characterized in that, Plating device two includes a device base, positioning blocks, pressing blocks, and positioning plugs. The device base is a two-layer annular part made of aluminum alloy material, divided into an upper disc and a lower chassis. Inner baffles and outer baffles are provided on the inner and outer sides of the base. The upper disc is designed with evenly distributed rectangular stepped grooves and threaded holes for the positioning and installation of positioning block c, and the spraying surfaces of the pressure side and suction side wear-resistant blocks of the blade are tangent to the circumference. The lower chassis is positioned and connected to the spraying equipment, and the upper disc and the lower chassis are connected into one body through multiple aluminum alloy struts. The positioning block c is positioned through the flange runner profile and flange side surface of the blade crown and is a quick-release and independent structure. The pressing block is pressed through the top of the blade crown and is a quick-release and independent structure. The positioning plug is located at the center of the device and is used for the positioning of the device and the workbench.

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