A method for plating a gamma-TiAl material turbine blade serrated crown wear resistant coating

Abstract

The present application relates to the technical field of metal material plating, in particular to a kind of γ-TiAl material turbine blade sawtooth crown wear-resistant coating plating method, it includes multi-station special plating device and aviation kerosene oxygen mixed fuel supersonic flame spraying process.Plating device is divided into two kinds of linear arrangement and annular arrangement, respectively realize 15 pieces and 30 pieces of blade one time clamping plating, significantly improve efficiency;Device realizes accurate positioning and non-spraying area protection by positioning block, pressing plate assembly and other structures.Co-Mo-Cr-Si wear-resistant coating is plated by using supersonic flame spraying process, heat input is low, coating is dense, and bonding strength is high;Subsequent grinding processing makes coating surface roughness reach Ra<0.8 μm.The present application solves the problem of high heat input and low construction efficiency in the prior art, and meets the requirements of high precision and high reliability for aeroengine.

Description

Technical Field

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

[0002] As a core component, aircraft engine turbine blades work for a long time in a harsh environment with high temperature, high pressure, high speed, strong turbulence and alternating multiple sources of large loads. Their performance directly affects the reliability and efficiency of the engine. As an important structure of the turbine blade, the serrated crown, also known as the "Z"-shaped blade crown, adopts a tightness design for the working surface. Through the close fit of the contact surface, it can reduce the leakage from the blade tip to the blade back, reduce the underflow loss of the turbine components, and improve the turbine efficiency; when adjacent blade crowns are pressed tightly, the twisting and bending deformation of the blades can be reduced, the blade rigidity can be enhanced, and the vibration frequency of the blades can be increased; the friction between adjacent blade crowns can absorb the energy generated by the vibration of the blades, 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 micro-motion fatigue due to frequent friction, thermal shock and micro-motion wear, which can lead to crack initiation or expansion, seriously affecting the service life and safety of the blades. γ-TiAl-based materials have a low density (about 4.0g / cm 3 ), high elastic modulus, and excellent high-temperature strength and creep resistance make it an ideal choice for a new generation of high-temperature structural materials. Using it to replace nickel-based high-temperature alloys can significantly reduce component weight, improve engine thrust-to-weight ratio, and reduce fuel consumption and emissions. However, γ-TiAl has a low hardness (HV300-500), weak wear resistance and fretting wear resistance, and is easily oxidized and brittle at high temperatures. Surface damage can lead to catastrophic failure. Therefore, applying a wear-resistant coating to the contact surface of the serrated crown has become a key measure to extend the service life and improve the reliability of γ-TiAl turbine blades.

[0003] At present, the coating methods for wear-resistant coatings on the contact surfaces of serrated crowns mainly include micro-beam argon arc cladding, vacuum high-temperature brazing and laser cladding. However, these methods have many shortcomings. Micro-beam argon arc cladding is prone to deformation or oxidation of the TiAl matrix due to the high arc temperature and large heat input, and leads to welding defects and an excessively long heat-affected zone, which seriously restricts the safe use of the blades. At the same time, the process is complex, requires inert gas protection, and is relatively expensive. In vacuum brazing, the brazing layer is easily softened or oxidized at high temperatures, and its long-term reliability is insufficient. In addition, the wettability of the brazing material and the hard wear-resistant layer material is poor, making it difficult to form a high-performance coating. Although laser cladding is a metallurgical bond, its heat input is high, and the coating is prone to cracking during rapid cooling, requiring tempering treatment to eliminate stress.

[0004] The plated area of ​​the blade's serrated crown contact surface is small, and the high-temperature, high-velocity flame erosion is significant during supersonic flame spraying. How to effectively protect the non-sprayed area from overspray is key to the supersonic flame spraying process. High-temperature pressure-sensitive tape is a commonly used protective tool, but it is extremely prone to high-temperature combustion during supersonic flame spraying, resulting in protection failure. High-temperature resistant adhesive putty was used to protect the non-plated area of ​​the blade, leaving only the serrated crown contact surface exposed. The putty was then placed in a 100°C drying oven and heated for 30 minutes to cure. The spray test results showed that the cured adhesive putty was unable to resist the high-temperature, high-velocity flame erosion, consumed too quickly, and deformed severely, failing to effectively protect the non-plated area. The use of conformable rubber tooling produced significant deformation after only five supersonic flame spraying erosions.

[0005] Furthermore, existing coating technologies often suffer from high heat input, low construction efficiency, and poor adaptability to complex shapes, making them unable to meet the requirements for efficient production of wear-resistant coatings for γ-TiAl turbine blade serrations. Therefore, developing a suitable coating method for γ-TiAl turbine blade serrations that can effectively reduce heat input while improving coating quality and production efficiency has become a pressing technical challenge. Summary of the Invention

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

[0007] The technical solution of the present invention is:

[0008] A method for plating a wear-resistant coating on a serrated crown of a turbine blade made of γ-TiAl material comprises the following steps:

[0009] Step 1: Pre-treating the surface of the area to be plated of the turbine blade serrated crown to achieve a surface roughness of Ra 2.0-3.8 μm;

[0010] Step 2: Use a multi-station dedicated coating device to clamp and position the blade and protect the non-spraying area;

[0011] Step 3: Using a supersonic flame spraying process of aviation kerosene-oxygen mixed fuel, a cobalt-molybdenum-chromium-silicon wear-resistant coating with a thickness of 0.30-0.40 mm is sprayed on the surface of the blade. During the spraying process, the blade is cooled by air and the blade temperature is monitored in real time to ensure that it does not exceed 204°C.

[0012] Step 4: Grind the sprayed coating to give it a uniform metallic luster.

[0013] The components of the cobalt-molybdenum-chromium-silicon wear-resistant coating powder include Mo: 27.0~30.0wt%, Cr: 16.5~18.5wt%, Si: 3.0wt%~3.8wt%, and the balance is Co, and the powder particle size distribution range must meet the following requirements: powder with a particle size of less than 75μm is 100.0wt%, powder with a particle size of 45μm~75μm is not more than 8.0wt%, powder with a particle size of less than 45μm is not less than 92.0wt%, powder with a particle size of 20μm~45μm is 55.0~70.0 wt%, and powder with a particle size of less than 10μm is not more than 8.0wt%.

[0014] Furthermore, in the above-mentioned method for plating a wear-resistant coating on a serrated crown of a turbine blade made of γ-TiAl material, the surface pretreatment process in step 1 is to use a press-in sandblasting gun to perform sandblasting on the area to be plated, the sand mold is 60# white corundum sand, the sandblasting pressure is 0.25~0.35 MPa, the sandblasting distance is 140~180 mm, the sandblasting angle is 55°~85°, the sandblasting gun moving speed is 5 mm / s, and the sandblasting gun nozzle diameter is 7.0~8.5 mm; spraying is performed within 2 hours after sandblasting.

[0015] Furthermore, in the above-mentioned method for coating a wear-resistant coating on a serrated crown of a turbine blade made of γ-TiAl material, in step 3, the spraying powder is dried in a temperature range of 66 to 82°C for at least 1 hour before spraying and stirred for 10 to 15 minutes before use, and spraying is performed after detecting the powder feeding rate and nozzle status.

[0016] Furthermore, in the above-mentioned method for coating a wear-resistant coating on a serrated crown of a turbine blade made of γ-TiAl material, step 3 adopts a supersonic flame spraying equipment based on aviation kerosene-oxygen mixed fuel for spraying, and the spraying process parameters include: barrel length is 101.6 mm, nozzle diameter is 10.5-11.5 mm, kerosene flow rate is 21-25 L / h, oxygen flow rate is 850-930 NLPM, spraying distance is 350-380 mm, powder feeding rate is 53-63 g / min, gun moving speed is 350-450 mm / s, spray gun angle is 40°-60°, carrier gas is argon, and carrier gas flow rate is 4.5-5.5 NLPM.

[0017] Furthermore, in the above-mentioned method for coating a wear-resistant coating on a serrated crown of a turbine blade made of γ-TiAl material, the air blowing cooling process parameters include: cooling air pressure 0.3~0.5MPa, cooling air distance 290~380 mm, cooling air angle 70°~90°, and cooling air duct diameter 7.0~9.0mm; 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.

[0018] Furthermore, in the above-mentioned method for coating a wear-resistant coating on the serrated crown of a turbine blade made of γ-TiAl material, the serrated crown is ground using a single-sided creep grinder, with 5 passes, and the machining removal amounts are 0.03mm, 0.02mm, 0.02mm, 0.01mm, and 0.01mm respectively. The grinding wheel linear speed is 25m / s, and finally the surface roughness Ra of the coating is less than 0.8μm.

[0019] Furthermore, in the above-mentioned method for plating wear-resistant coating on serrated crown of turbine blade made of γ-TiAl material, the multi-station special plating device can realize the simultaneous plating of basin-facing and back-facing wear-resistant coating on 15 to 30 blades in one clamping, including a plating device 1 adopting a linear arrangement clamping method and a plating device 2 adopting a circular arrangement clamping method.

[0020] Furthermore, in the above-mentioned method for plating a wear-resistant coating on a serrated crown of a turbine blade made of γ-TiAl material, the first plating device includes a support assembly, a positioning block, a pressure plate assembly, a cap assembly, a baffle and a block, a guard plate, a plate buckle, and a bolt with a flange;

[0021] 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 block, and the base is provided with a rectangular groove for positioning the pressure plate assembly, a threaded hole, and a threaded hole for installing the plate buckle;

[0022] The positioning blocks are used to position the blades, including positioning blocks for the outside of the entire row of parts and positioning blocks for the remaining workstations, and are positioned through the flow channel profile and side surfaces of the blade crown;

[0023] The pressure plate assembly includes a left pressure plate assembly, a middle pressure plate assembly and a right pressure plate assembly, all of which are welded assemblies and consist of a positioning seat, a support seat, a beam and a protection plate. The positioning seat is positioned according to the flow channel 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, which cooperates with the rectangular groove on the base of the support assembly, the flange bolt and the plate buckle for positioning; the protection plate is used to protect the non-spraying area;

[0024] The device is sealed around the device by the baffle on the base of the support assembly and the protective plates of the left and right pressure plate assemblies, wherein the baffles on the left and right sides of the base are fixed to the base by blocks;

[0025] The cap assembly is used to press parts and protect non-spraying areas. It is positioned with the support assembly through the cylindrical pins on both sides and 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-spraying areas that are not covered by the cap assembly.

[0026] Furthermore, in the above-mentioned method for plating a wear-resistant coating on a serrated crown of a turbine blade made of γ-TiAl material, the second plating device includes a device base, a positioning block, a pressing block and a positioning plug;

[0027] The base of the device is a two-layer annular member made of aluminum alloy, divided into an upper disc and a lower chassis. The inner and outer sides of the base are provided with inner and outer baffles. The upper disc is designed with evenly distributed rectangular step grooves and threaded holes for positioning and installing the positioning block C, and the spraying surface of the blade basin and the back wear-resistant block is 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 by multiple aluminum alloy pillars.

[0028] The positioning block c is positioned by the blade crown edge plate flow channel profile and the edge plate side surface, and is a quick-release, independent structure;

[0029] The pressing block is pressed through the top of the leaf crown and is a quick-release, independent structure;

[0030] The positioning plug is located at the center of the device and is used for positioning the device and the workbench.

[0031] Advantages and beneficial effects of the present invention:

[0032] The combination of a supersonic flame spraying process and a dedicated multi-station coating device significantly reduces heat input during the spraying process, avoiding oxidation and deformation of the γ-TiAl material caused by high temperatures, while also improving the coating's density and bonding strength. The dedicated multi-station coating device can produce 15 to 30 blades with basin- and back-facing wear-resistant coatings in a single clamping operation, significantly improving production efficiency and meeting the needs of mass production. Furthermore, the post-spraying grinding process further optimizes the coating's surface quality, achieving a roughness Ra of less than 0.8μm, meeting the high-precision and high-reliability requirements of aircraft engines. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Schematic diagram of the area to be sprayed with the wear-resistant coating on the serrated crown of a γ-TiAl turbine blade, where (a) is the spraying area in the direction of the blade basin and (b) is the spraying area in the direction of the blade back;

[0034] Figure 2 Schematic diagram of the spraying area when using the coating device, where (a) is the spraying area in the direction of the blade basin, and (b) is the spraying area in the direction of the blade back;

[0035] Figure 3 Schematic diagram of the spraying area when using the second coating device, where (a) is the spraying area in the direction of the blade basin, and (b) is the spraying area in the direction of the blade back;

[0036] Figure 4 is a three-dimensional schematic diagram of a plating device 1;

[0037] Figure 5 It is a front view of the plating device 1;

[0038] Figure 6 is a top view of the first plating device;

[0039] Figure 7 for Figure 5 AA surface diagram;

[0040] Figure 8 A three-dimensional schematic diagram of a support assembly of a plating device;

[0041] Figure 9 A schematic diagram of a positioning block for the outer side of a whole row of parts in a plating device;

[0042] Figure 10 FIG. b is a schematic diagram of a positioning block for the remaining workstations of a plating device;

[0043] Figure 11 Schematic diagram of the inside and outside of a left pressure plate assembly of a plating device, wherein (a) is a schematic diagram of the inside, and (b) is a schematic diagram of the outside;

[0044] Figure 12 Schematic diagram of the inside and outside of an intermediate pressure plate assembly of a plating device, wherein (a) is a schematic diagram of the inside, and (b) is a schematic diagram of the outside;

[0045] Figure 13 Schematic diagrams of the inside and outside of a right pressure plate assembly of a plating device, wherein (a) is a schematic diagram of the inside, and (b) is a schematic diagram of the outside;

[0046] Figure 14 A schematic diagram of a cap assembly of a plating device;

[0047] Figure 15 It is a front view of the second plating device;

[0048] Figure 16 A three-dimensional schematic diagram of the second base of the plating device;

[0049] Figure 17 This is a schematic diagram of the second positioning block c of the plating device;

[0050] Figure 18 It is a schematic diagram of the second pressing block of the plating device;

[0051] Figure 19 This is a cross-sectional tissue splicing diagram of the coating simulation component in Example 2 of the present invention;

[0052] Figure 20 The microstructure diagrams of the coatings after spraying of the embodiments of the present invention are shown in Figures 1 and 3, respectively, wherein (a) is Example 1, (b) is Example 3, (c) is Example 4, and (d) is Example 5.

[0053] In the figure, 1-support assembly; 101-upper support plate; 102-base; 2-positioning block a, 3-positioning block b; 4-left pressure plate assembly; 401-positioning seat; 402-support seat; 403-beam; 404-protective plate; 5-middle pressure plate assembly; 6-right pressure plate assembly; 7-cap assembly, 8-baffle; 9-baffle, 10-guard plate, 11-plate buckle; 12-flange bolt; base 13; 1301-upper disc; 1302-lower chassis; 1303-inner baffle; 1304-outer baffle; 1305-pillar; 14-positioning block c; 15-pressing block; 16-positioning plug; 17-blade basin direction; 18-blade back direction. DETAILED DESCRIPTION

[0054] In a specific embodiment, the present invention provides a method for coating a wear-resistant coating on the serrated crown of a turbine blade made of γ-TiAl. Through the design and application of a multi-station dedicated coating device and the specific implementation of a supersonic flame spraying process, efficient, high-quality wear-resistant coating can be achieved by completing both the blade's base and back surfaces in a single clamping operation. The technical solution of the present invention is described in detail below with reference to the accompanying drawings and examples.

[0055] like Figure 1 The figure shows the area of ​​the γ-TiAl turbine blade serrated crown to be sprayed with a wear-resistant coating. When implementing the present invention, a multi-station dedicated coating device must first be prepared. The device is divided into two structural forms: a coating device 1 that adopts a linear arrangement clamping method and a coating device 2 that adopts a circular arrangement clamping method. The coating area when using the coating devices 1 and 2 is as follows: Figure 2 、 Figure 3 As shown, the blade base 17 and the blade rear 18 are sprayed.

[0056] like Figure 4-14 The first plating device can be used for clamping 15 blades at a time, including a support assembly 1, a positioning block, a pressure plate assembly, a cap assembly 7, a baffle 8 and a block 9, a guard plate 10, a plate buckle 11 and a flange bolt 12;

[0057] The support assembly 1 is used to support the entire device, including 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 block, and the base 102 is provided with a rectangular groove for positioning the pressure plate assembly, a threaded hole, and a threaded hole for installing the plate buckle;

[0058] The positioning blocks are used to position the blades, including positioning blocks a2 for the outside of the entire row of parts and positioning blocks b3 for the remaining workstations, and are positioned through the flow channel profile and side surfaces of the blade crown;

[0059] The pressure plate assembly includes a left pressure plate assembly 4, a middle pressure plate assembly 5 and a right pressure plate assembly 6, all of which are welded assemblies and consist of a positioning seat 401, a support seat 402, a beam 403 and a protection plate 404. The positioning seat 401 is positioned according to the flow channel 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, which cooperates with the rectangular groove on the base 102 of the support assembly 1, the flange bolt 12 and the plate buckle 11 for positioning; the protection plate 404 is used to protect the non-spraying area;

[0060] The device is sealed around the device by the baffle 8 on the base 102 of the support assembly 1 and the protective plates 404 of the left and right pressure plate assemblies, wherein the baffles 8 on the left and right sides of the base are fixed to the base by the blocks 9;

[0061] The cap assembly 7 is used to press the parts and protect the non-spraying area. It is positioned with the support assembly 1 through the cylindrical pins on both sides and connected to the support assembly 1 through the threaded hole in the middle. The guard plate 10 is located in the gap of the cap assembly 7 and is used to protect other non-spraying areas that are not covered by the cap assembly 7.

[0062] like Figure 15-18 As shown, the second plating device includes a device base 13, a positioning block c14, a pressing block 15 and a positioning plug 16;

[0063] The device base 13 is a two-layer annular member made of aluminum alloy, divided into an upper disc 1301 and a lower chassis 1302. Inner and outer baffles 1303 and 1304 are provided on the inside and outside of the base. The upper disc 1301 is designed with 30 evenly distributed rectangular step grooves and threaded holes for positioning and installing the positioning block C14. The sprayed surface of the blade basin and back wear block is tangent to the circumference. The lower chassis is positioned and connected to the spraying equipment, and the upper disc and lower chassis are connected into one body by multiple aluminum alloy struts 1305. The positioning block C14 is positioned by the edge plate flow channel profile and edge plate side of the blade crown and is a quick-release, independent structure.

[0064] The pressing block 15 is pressed by the top of the blade crown and is a quick-release, independent structure;

[0065] The positioning plug 16 is located at the center of the device and is used to position the device and the workbench.

[0066] After the plating equipment is prepared, the working stage begins, which specifically includes the following steps:

[0067] Step 1, performing surface pretreatment on the area to be plated of the serrated crown of the turbine blade, using a press-in sandblasting gun to perform sandblasting on the area to be plated, the sand mold is 60# white corundum sand, the sandblasting pressure is 0.25~0.35 MPa, the sandblasting distance is 140~180 mm, the sandblasting angle is 55°~85°, the sandblasting gun moving speed is 5 mm / s, and the sandblasting gun nozzle diameter is 7.0~8.5 mm; spraying is performed within 2 hours after sandblasting to make the surface roughness Ra 2.0~3.8 μm;

[0068] Step 2: Use a multi-station dedicated coating device to clamp and position the blade and protect the non-spraying area;

[0069] Step 3: Using a supersonic flame spraying process of aviation kerosene-oxygen mixed fuel, a cobalt-molybdenum-chromium-silicon wear-resistant coating with a thickness of 0.30-0.40 mm is sprayed on the surface of the blade. During the spraying process, the blade is cooled by air and the blade temperature is monitored in real time to ensure that it does not exceed 204°C.

[0070] Before spraying, dry the spray powder at a temperature range of 66-82°C for at least 1 hour and stir it for 10-15 minutes before use. Spray after checking the powder feeding rate and nozzle status;

[0071] The spraying process parameters include: barrel length 101.6 mm, nozzle diameter 10.5-11.5 mm, kerosene flow rate 21-25 L / h, oxygen flow rate 850-930 NLPM, spraying distance 350-380 mm, powder feed rate 53-63 g / min, gun movement speed 350-450 mm / s, spray gun angle 40°-60°, carrier gas argon, and carrier gas flow rate 4.5-5.5 NLPM;

[0072] Air cooling process parameters include: cooling air pressure 0.3-0.5 MPa, cooling air distance 290-380 mm, cooling air angle 70°-90°, cooling air duct diameter 7.0-9.0 mm; an infrared thermometer is used to monitor the part temperature; if the part temperature exceeds 204°C, spraying is interrupted and the part is cooled;

[0073] Step 4: Grind the sprayed coating. Use a single-sided creep grinder to grind the serrated crown. The number of passes is 5. 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 has a uniform metallic luster and the surface roughness Ra of the coating is less than 0.8 μm.

[0074] The components of the cobalt-molybdenum-chromium-silicon wear-resistant coating powder include Mo: 27.0~30.0wt%, Cr: 16.5~18.5wt%, Si: 3.0wt%~3.8wt%, and the balance is Co, and the powder particle size distribution range must meet the following requirements: powder with a particle size of less than 75μm is 100.0wt%, powder with a particle size of 45μm~75μm is not more than 8.0wt%, powder with a particle size of less than 45μm is not less than 92.0wt%, powder with a particle size of 20μm~45μm is 55.0~70.0 wt%, and powder with a particle size of less than 10μm is not more than 8.0wt%.

[0075] Next, the plating process of the present invention will be further described in detail with reference to the embodiments.

[0076] Example 1

[0077] This embodiment provides a method for plating a wear-resistant coating on a serrated crown of a turbine blade made of γ-TiAl material, comprising the following steps:

[0078] Step 1: Step 1, the surface of the to-be-plated area of ​​the turbine blade serrated crown is pretreated, and a press-in sandblasting gun is used to perform sandblasting on the to-be-plated area. The sand mold is 60# white corundum sand, the sandblasting pressure is 0.25 MPa, the sandblasting distance is 140 mm, the sandblasting angle is 55°, the sandblasting gun moving speed is 5 mm / s, and the sandblasting gun nozzle diameter is 7.0 mm. Spraying is performed within 2 hours after sandblasting to achieve a surface roughness of Ra 2.0 μm.

[0079] Step 2: Use a coating device to clamp and position the blades and protect the non-spraying area;

[0080] Step 3: Spray a 0.30 mm thick cobalt-molybdenum-chromium-silicon wear-resistant coating on the blade surface using a kerosene-oxygen mixed fuel supersonic flame spraying process. During the spraying process, the blade is cooled by air and the blade temperature is monitored in real time to ensure that it does not exceed 204°C.

[0081] Before spraying, dry the spray powder at 66°C for 1 hour and stir it for 10 minutes before use. Test the powder feeding rate and nozzle status before spraying.

[0082] The spraying process parameters include: barrel length 101.6 mm, nozzle diameter 10.5 mm, kerosene flow rate 21 L / h, oxygen flow rate 850 NLPM, spray distance 350 mm, powder feed rate 53 g / min, gun movement speed 350 mm / s, spray gun angle 40°, carrier gas argon, and carrier gas flow rate 4.5-5.5 NLPM;

[0083] The air cooling process parameters include: cooling air pressure 0.3 MPa, cooling air distance 290 mm, cooling air angle 70°, and cooling air duct diameter 7.0 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.

[0084] Step 4: Grind the sprayed coating. Use a single-sided creep grinder to grind the serrated crown. The number of passes is 5. 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 has a uniform metallic luster and the surface roughness Ra of the coating is 0.7 μm.

[0085] The components of the cobalt-molybdenum-chromium-silicon wear-resistant coating powder include Mo: 27.0wt%, Cr: 16.5wt%, Si: 3.0wt%, and the balance is Co, and the powder particle size distribution range must meet the following requirements: 100.0wt% of powder with a particle size of less than 75μm, 8.0wt% of powder with a particle size of 45μm~75μm, 92.0wt% of powder with a particle size of less than 45μm, 55.0wt% of powder with a particle size of 20μm~45μm, and 8.0wt% of powder with a particle size of less than 10μm.

[0086] Example 2

[0087] This embodiment provides a method for plating a wear-resistant coating on a serrated crown of a turbine blade made of γ-TiAl material, comprising the following steps:

[0088] Step 1: Surface pretreatment is performed on the area to be plated of the serrated crown of the turbine blade. A press-in sandblasting gun is used to perform sandblasting on the area to be plated. The sand mold is 60# white corundum sand, the sandblasting pressure is 0.35 MPa, the sandblasting distance is 180 mm, the sandblasting angle is 85°, the sandblasting gun movement speed is 5 mm / s, and the sandblasting gun nozzle diameter is 8.5 mm. Spraying is performed within 2 hours after sandblasting to achieve a surface roughness of Ra 3.8 μm.

[0089] Step 2: Use the second coating device to clamp and position the blade, and protect the non-spraying area;

[0090] Step 3: Spray a 0.40 mm thick cobalt-molybdenum-chromium-silicon wear-resistant coating on the blade surface using a kerosene-oxygen mixed fuel supersonic flame spraying process. During the spraying process, the blade is cooled by air and the blade temperature is monitored in real time to ensure that it does not exceed 204°C.

[0091] Before spraying, dry the spray powder at 82°C for 1 hour and stir it for 15 minutes before use. Spray after checking the powder feeding rate and nozzle status.

[0092] The spraying process parameters include: barrel length 101.6 mm, nozzle diameter 11.5 mm, kerosene flow rate 25 L / h, oxygen flow rate 930 NLPM, spray distance 380 mm, powder feed rate 63 g / min, gun travel speed 450 mm / s, spray gun angle 60°, carrier gas argon, and carrier gas flow rate 5.5 NLPM;

[0093] The air cooling process parameters include: cooling air pressure 0.5MPa, cooling air distance 380mm, cooling air angle 90°, cooling air duct diameter 9.0mm; an infrared thermometer is used to monitor the part temperature; if the part temperature exceeds 204℃, spraying is interrupted and the part is cooled;

[0094] Step 4: Grind the sprayed coating. Use a single-sided creep grinder to grind the serrated crown. The number of passes is 5. 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 has a uniform metallic luster and the surface roughness Ra of the coating is less than 0.8 μm.

[0095] The components of the cobalt-molybdenum-chromium-silicon wear-resistant coating powder include Mo: 30.0wt%, Cr: 18.5wt%, Si: 3.8wt%, and the balance is Co, and the powder particle size distribution range must meet the following requirements: 100.0wt% of powder with a particle size of less than 75μm, 6.0wt% of powder with a particle size of 45μm~75μm, 94.0wt% of powder with a particle size of less than 45μm, 70.0wt% of powder with a particle size of 20μm~45μm, and 5.0wt% of powder with a particle size of less than 10μm.

[0096] Cut the simulated part after spraying in Example 2 and make metallographic specimens to observe the spraying effect. Figure 19 As shown, the cross section of the simulated part was observed under a microscope at 200 times magnification. The coating had good structure, good bonding between the coating and the substrate, and the coating completely covered the wear-resistant block spraying area, which could meet the service requirements of the blade.

[0097] Example 3

[0098] The difference between this embodiment and embodiment 1 is that, in the spraying process parameters, the kerosene flow rate is 24 / h.

[0099] Example 4

[0100] The difference between this embodiment and embodiment 1 is that, in the spraying process parameters, the oxygen flow rate is 890 NLPM.

[0101] Example 5

[0102] The difference between this embodiment and embodiment 1 is that, in the spraying process parameters, the spraying distance is 380 mm.

[0103] like Figure 20 As shown, the microstructure of the coatings after spraying of Examples 1, 3, 4, and 5 was examined. The coatings were uniform and complete, without delamination, transverse cracks, or interface separation. The pores and oxides in the coatings were evenly distributed.

[0104] Comparison of the four groups of microstructures revealed that:

[0105] When the kerosene flow rate increases, the porosity of the coating tissue decreases and the oxides decrease;

[0106] When the oxygen flow rate decreases, the porosity of the coating increases and the oxide decreases;

[0107] When the spraying distance increases, the porosity of the coating increases and the amount of oxides increases;

[0108] The comparison of the tensile bonding strength, surface Rockwell hardness and microhardness of the coatings after spraying of Examples 1, 3, 4 and 5 is shown in Table 1:

[0109] Table 1 Comparison of coating tensile bond strength, surface Rockwell hardness and microhardness

[0110] Example Average tensile strength MPa Surface 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

[0111] To meet the demanding service conditions of turbine blades, the coating's average tensile bond strength should be no less than 41 MPa, with a single value no less than 38 MPa; its average surface Rockwell hardness should be no less than 87 HR15N, with a single value no less than 85 HR15N; and its average microhardness should be no less than 575 HV under a load of 300 g, with a single value no less than 500 HV. The coating performance sprayed in the above embodiments meets the requirements.

Claims

1. A method for plating a wear-resistant coating on a serrated crown of a turbine blade made of γ-TiAl material, characterized in that: The following steps are involved: Step 1: Pre-treating the surface of the area to be plated of the turbine blade serrated crown to achieve a surface roughness of Ra 2.0-3.8 μm; Step 2: Use a multi-station dedicated plating device to clamp and position the blades and protect the non-spraying area; the multi-station dedicated plating device can achieve simultaneous plating of 15 to 30 blades with basin-facing and back-facing wear-resistant coatings in one clamping, and adopts a linear arrangement clamping method of the plating device 1; The first plating device includes a support assembly, a positioning block, a pressure plate assembly, a cap assembly, a baffle and a baffle, 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 block, and the base is provided with a rectangular groove for positioning the pressure plate assembly, a threaded hole, and a threaded hole for installing the plate buckle; The positioning blocks are used to position the blades, including positioning blocks a for the outside of the entire row of parts and positioning blocks b for the remaining workstations, and are positioned through the flow channel profile and side surfaces of the blade crown; The pressure plate assembly includes a left pressure plate assembly, a middle pressure plate assembly and a right pressure plate assembly, all of which are welded assemblies and consist of a positioning seat, a support seat, a beam and a protection plate. The positioning seat is positioned according to the flow channel 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, which cooperates with the rectangular groove on the base of the support assembly, the flange bolt and the plate buckle for positioning; the protection plate is used to protect the non-spraying area; The device is sealed around the device by the baffle on the base of the support assembly and the protective plates of the left and right pressure plate assemblies, wherein the baffles on the left and right sides of the base are fixed to the base by blocks; The cap assembly is used to press the parts and protect the non-spraying area. It is positioned with the support assembly through the cylindrical pins on both sides and connected to the support assembly through the threaded hole in the middle. The guard plate is located in the gap of the cap assembly to protect other non-spraying areas that are not covered by the cap assembly. Step 3: Using a supersonic flame spraying process of aviation kerosene-oxygen mixed fuel, a cobalt-molybdenum-chromium-silicon wear-resistant coating with a thickness of 0.30-0.40 mm is sprayed on the surface of the blade. During the spraying process, the blade is cooled by air and the blade temperature is monitored in real time to ensure that it does not exceed 204°C. The spraying process parameters include: barrel length 101.6 mm, nozzle diameter 10.5-11.5 mm, kerosene flow rate 21-25 L / h, oxygen flow rate 850-930 NLPM, spraying distance 350-380 mm, powder feed rate 53-63 g / min, gun movement speed 350-450 mm / s, spray gun angle 40°-60°, carrier gas argon, and carrier gas flow rate 4.5-5.5 NLPM; Air cooling process parameters include: cooling air pressure 0.3-0.5 MPa, cooling air distance 290-380 mm, cooling air angle 70°-90°, cooling air duct diameter 7.0-9.0 mm; an infrared thermometer is used to monitor the part temperature; if the part temperature exceeds 204°C, spraying is interrupted and the part is cooled; Step 4: Grinding the sprayed coating. Specifically, the serrated crown is ground using a single-sided creep grinder. The number of passes is 5, 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, and the surface roughness Ra of the coating is finally reduced to less than 0.8 μm. The coating surface has a uniform metallic luster. The components of the cobalt-molybdenum-chromium-silicon wear-resistant coating powder include Mo: 27.0~30.0wt%, Cr: 16.5~18.5wt%, Si: 3.0wt%~3.8wt%, and the balance is Co, and the powder particle size distribution range must meet the following requirements: powder with a particle size of less than 75μm is 100.0wt%, powder with a particle size of 45μm~75μm is not more than 8.0wt%, powder with a particle size of less than 45μm is not less than 92.0wt%, powder with a particle size of 20μm~45μm is 55.0~70.0 wt%, and powder with a particle size of less than 10μm is not more than 8.0wt%.

2. The method for coating a wear-resistant coating on a γ-TiAl turbine blade serrated crown according to claim 1, characterized in that: In step 1, the surface pretreatment process is to use a press-in sandblasting gun to perform sandblasting on the area to be plated. The sand mold is 60# white corundum sand, the sandblasting pressure is 0.25~0.35 MPa, the sandblasting distance is 140~180mm, the sandblasting angle is 55°~85°, the sandblasting gun moving speed is 5mm / s, and the sandblasting gun nozzle diameter is 7.0~8.5mm; spraying is performed within 2 hours after sandblasting.

3. The method for plating a wear-resistant coating on a serrated crown of a γ-TiAl turbine blade according to claim 1, characterized in that: Step 3: Dry the spray powder at a temperature range of 66-82°C for at least 1 hour before spraying and stir it for 10-15 minutes before use. Spraying is performed after checking the powder feeding rate and nozzle status.

4. The method for coating a wear-resistant coating on a serrated crown of a γ-TiAl turbine blade according to claim 1, characterized in that: The first plating device can be replaced by a second plating device that adopts a ring-shaped arrangement and clamping method. The second plating device includes a device base, a positioning block, a pressing block and a positioning plug; The base of the device is a two-layer annular member made of aluminum alloy, divided into an upper disc and a lower chassis. The inner and outer sides of the base are provided with inner and outer baffles. The upper disc is designed with evenly distributed rectangular step grooves and threaded holes for positioning and installing the positioning block C, and the spraying surface of the blade basin and the back wear-resistant block is 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 by multiple aluminum alloy pillars. The positioning block c is positioned by the blade crown edge plate flow channel profile and the edge plate side surface, and is a quick-release, independent structure; The pressing block is pressed through the top of the leaf crown and is a quick-release, independent structure; The positioning plug is located at the center of the device and is used for positioning the device and the workbench.

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