A device and a vapor phase aluminizing method for synchronously preparing high-temperature protective aluminizing coating on inner cavity and outer surface of a workpiece

Abstract

The application discloses a device and a gas phase aluminizing method for synchronously preparing high-temperature protective aluminizing coating on the inner cavity and the outer surface of a workpiece, and belongs to the technical field of turbine power blades of an aero-engine and a gas turbine. The device comprises a lifting mechanism, a heating furnace, a reaction kettle, a bearing system, a main frame and an aluminizing tool, wherein the main frame is a vertical frame structure, the bearing system is arranged at the middle and lower parts of the main frame and is supported by the main frame, and the aluminizing tool is arranged on the bearing system; the reaction kettle is arranged directly above the bearing system, and the heating furnace is sleeved outside the reaction kettle to externally heat the reaction kettle; the lifting mechanism is fixed on the heating furnace, and the lifting mechanism is used for controlling the lifting and lowering of the heating furnace and the reaction kettle. The device has the advantages of simple structure, convenient operation, synchronous preparation of aluminizing coating on the inner cavity and the outer surface of the blade through one-time heat treatment, controllable thickness during preparation of the aluminizing coating, and low cost of the prepared coating.

Description

Technical Field

[0001] This invention relates to the field of aero-engine and gas turbine turbine blade technology, specifically to an apparatus and a vapor-phase aluminizing method for simultaneously preparing high-temperature protective aluminizing coatings on the inner cavity and outer surface of a workpiece. Background Technology

[0002] Turbine blades are core components in aero-engines and gas turbines operating in extremely harsh environments, and coating technology directly affects engine performance and lifespan. The core reason is that in the high-temperature combustion environment, the blade surface is subjected to prolonged exposure to temperatures exceeding 1000°C, leading to high-temperature oxidation and thermal corrosion damage from fuel impurities. The high-temperature alloy materials of the blades themselves cannot withstand the ever-increasing combustion temperature on their own. However, blade surface coatings can form a dense oxide film (such as Al2O3), effectively blocking the penetration of oxygen and corrosive media. Specifically, the coating mainly addresses three critical issues: 1. Resistance to high-temperature oxidation; 2. Resistance to high-temperature corrosion; 3. Withstanding extreme heat and stress. Vapor-phase aluminizing coating is one type of high-temperature protective coating for blades, typically used on the inner cavity and outer surface of turbine blades. While the process for preparing aluminizing coatings on the inner cavity or outer surface of a blade alone is simple and mature, the process for preparing aluminizing coatings on both the inner cavity and outer surface of a blade simultaneously is relatively complex.

[0003] Currently, there are several processes for preparing aluminized coatings on the inner and outer surfaces of blades: (1) inner cavity powder embedding method + outer surface powder embedding method; (2) inner cavity powder embedding method + outer surface slurry method; (3) inner cavity powder embedding method + outer surface vapor phase aluminizing method; (4) inner cavity and outer surface CVD chemical vapor deposition method. Among them, the advantages of processes (1)-(3) are: simple process and low cost. The disadvantages are that the powder used for embedding is not easy to clean and two heat treatments are required to prepare inner and outer surface coatings, and the coating thickness is not easy to control. The advantages of process (4) are that the inner and outer surface aluminized coatings are prepared in one heat treatment and the coating thickness is controllable. The disadvantages are that the CVD chemical vapor deposition equipment is expensive, the equipment structure is complex, the parts used are highly precise, the equipment maintenance cycle is long and the price is high, and the production cost is high.

[0004] Therefore, a device for simultaneously preparing aluminized coatings on the inner cavity and outer surface of blades is developed. The device has a simple structure and controllable cost. It can prepare coatings on the inner cavity or outer surface alone, or on both the inner and outer surfaces simultaneously. The thickness of the aluminized coating is controllable, and the coating preparation cost is low. Summary of the Invention

[0005] The purpose of this invention is to provide an apparatus and a vapor-phase aluminizing method for simultaneously preparing a high-temperature protective aluminizing coating on the inner cavity and outer surface of a workpiece. The apparatus has a simple structure and is easy to operate. It can achieve the simultaneous preparation of aluminizing coatings on the inner cavity and outer surface of a blade through a single heat treatment. Furthermore, the thickness of the aluminizing coating is controllable during preparation, and the coating preparation cost is low.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A device for simultaneously preparing a high-temperature protective aluminizing coating on the inner cavity and outer surface of a workpiece includes a lifting mechanism, a heating furnace, a reaction vessel, a supporting system, a main frame, and an aluminizing fixture. The main frame is a vertical frame structure. The supporting system is located in the lower middle part of the main frame and supported by it. The aluminizing fixture is mounted on the supporting system. The reaction vessel is located directly above the supporting system. The heating furnace is fitted around the outside of the reaction vessel to provide external heating. The lifting mechanism is fixed to the heating furnace and controls the lifting and lowering of the heating furnace and the reaction vessel.

[0007] Furthermore, the reactor includes a sealed pressure furnace body, with a furnace cavity formed inside. A cooling water jacket is provided at the bottom of the furnace body, and a sealing flange I is provided at the bottom of the cooling water jacket for cooperation with a sealing flange II in the support system to form a seal. The bottom of the reactor is a certain distance from the top of the support system to facilitate operation by the operator. The heating furnace is equipped with heating elements and heat-insulating brick material to provide a high-temperature reaction temperature field for the reactor and maintain the temperature. The heating furnace is fitted onto the outside of the furnace body of the reactor.

[0008] Furthermore, the bearing system includes a support platform with an inverted "U"-shaped longitudinal section, a sealing flange II, and a cylindrical bearing platform, wherein: the lower ends of the vertical portions on both sides of the support platform are fixed to the main frame, the sealing flange II is fixed to its top horizontal surface, and the bearing platform is fixed to the sealing flange II; the bearing platform is provided with several through holes in the vertical direction for installing the aluminizing tooling; the circumferential edge of the upper surface of the sealing flange II is provided with a sealing groove, and a sealing ring is placed in the sealing groove for sealing with the sealing flange I.

[0009] Furthermore, the aluminizing fixture includes a cover, a material holding cylinder, and a workpiece loading cylinder. The material holding cylinder is placed on top of the workpiece loading cylinder, and the cover is located on the top of the material holding cylinder. The workpiece loading cylinder is a cylindrical structure closed at both ends, and a diamond-shaped hole is opened on its upper surface for placing turbine blades. Furthermore, the material container is a double-layer cylindrical structure, comprising an inner cylindrical body and an outer cylindrical body arranged coaxially. The outer cylindrical body is an airtight cylinder, and the inner cylindrical body is a porous cylinder made of a porous plate. The inner cylindrical body is open at both ends, and the annular space formed between the outer and inner cylindrical bodies is a material container II, which is open at the top and closed at the bottom. The material container II contains a diffusion agent and an activator for vapor phase aluminizing.

[0010] Furthermore, in the aluminizing tooling, an upward-facing annular protrusion is provided at the circumferential position (edge) of the upper surface of the workpiece loading cylinder, which can limit the material container placed on the upper surface of the workpiece loading cylinder; the inner diameter of the annular protrusion is slightly larger than the outer diameter of the material container. Furthermore, the diamond-shaped holes on the upper surface of the workpiece loading cylinder allow the tenon of the turbine blade to pass through, but the truss of the turbine blade cannot pass through, thereby fixing the turbine blade. Furthermore, the sidewall of the workpiece loading cylinder has a double-layer structure, with the outer layer being an airtight cylinder and the inner layer being a porous cylinder made of a porous plate; wherein: the annular space formed between the inner and outer layers is a material holding tank I, which contains a diffusion agent and an activator for vapor phase aluminizing.

[0011] Furthermore, the aluminizing fixture also includes an air inlet pipe. One end of the air inlet pipe is fixed to the center of the bottom surface of the workpiece loading cylinder and is connected to the inside of the workpiece loading cylinder. The other end is connected to an argon gas inlet pipe. The air inlet pipe is used to introduce argon gas into the interior of the aluminizing fixture (the inside of the workpiece loading cylinder and the inside of the material container). An argon gas cylinder is connected to the argon gas inlet pipe 7. An argon gas flow meter and an oil-water separator are also provided on the argon gas inlet pipe 7 near the argon gas cylinder. A 25-35° chamfer is provided on the air inlet pipe 25-35mm away from the bottom surface of the workpiece loading cylinder for sealing.

[0012] Furthermore, the aluminizing tooling is made of 316 stainless steel or 2520 stainless steel.

[0013] Furthermore, the main frame is a rectangular frame structure containing four columns, with adjacent columns connected by crossbeams; the lifting mechanism includes a hydraulic cylinder and a fixed frame, the fixed frame being a horizontal "+" shaped structure, the lower end of the hydraulic cylinder output shaft being fixed at the center of the fixed frame, and the fixed frame being fixed to the upper surface of the heating furnace body; the lifting mechanism uses the four columns of the main frame as guide supports, and the heating furnace body, driven by the hydraulic cylinder of the lifting mechanism, achieves vertical movement along the four columns.

[0014] Furthermore, the device also includes a vacuum extraction pipe and an exhaust pipe. One end of the vacuum extraction pipe and the exhaust pipe are respectively installed on the support platform and connected to the space above the support platform, and the other end is respectively connected to the vacuum pump and the external ambient atmosphere; wherein: the exhaust pipe is equipped with a vacuum ball valve (to control the exhaust flow and close).

[0015] The method for simultaneously preparing high-temperature protective aluminized coatings on the inner cavity and outer surface of a workpiece using the aforementioned device is as follows: The supporting system is placed on the main frame 1 meter above the ground. The lifting mechanism raises the heating furnace and the reactor, and the tooling is placed at the through hole above the supporting system. The workpiece is placed with its tenon facing down in the diamond-shaped hole on the workpiece loading cylinder of the tooling. Raw materials for vapor phase aluminizing are placed in the material storage tank I (in the workpiece loading cylinder) and the material storage tank II (in the material storage cylinder) to ensure sufficient aluminum atmosphere is generated at high temperature. After the tooling is placed at the through hole above the supporting system, the lifting mechanism is used to lower the heating furnace and the reactor, so that the bottom sealing flange I of the reactor and the bottom sealing flange II of the supporting system are fitted and sealed. The vacuum pump is turned on to replace the impurity gas in the reactor furnace. First, the vacuum pump is used to evacuate the furnace and the pressure is emptied to -100KPa. High-purity argon is introduced into the furnace through each argon inlet pipe at a flow rate of 3L / min until the pressure reaches +1KPa, and then the vacuum pump is turned on. The pump continues to evacuate, repeating this operation three times. During the final evacuation, when argon gas is introduced to +1 kPa, the vacuum ball valve on the exhaust pipe is opened to vent the gas. Argon gas is continuously introduced at a flow rate of 3 L / min as an inert protective gas to ensure that the workpiece and tooling inside the reactor are not oxidized. After the impurity gas is vented, the heating system is turned on to raise the temperature to 950-1100℃ and held for 120-240 minutes. During the heating process, an aluminized coating is prepared on the inner cavity and outer surface of the workpiece. The aluminizing principle is as follows: the argon gas flow rate in the argon gas inlet pipe connected to the support system is set to 3 L / min, allowing argon gas to carry the aluminum atmosphere from the tenon teeth into the inner cavity flow channel, thus completing the preparation of the aluminized coating in the inner cavity. After the aluminized coatings on the inner cavity and outer surface are completed, the heating furnace is raised and cooled to room temperature, and then the reactor is raised to remove the workpiece.

[0016] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows: 1. The device and method of the present invention can simultaneously prepare aluminized coatings on the inner cavity and outer surface of a workpiece in a single heat treatment, and the coating thickness on the inner and outer surfaces can be precisely controlled. In the early research and development stage using this device, multiple workpiece processes can be developed together.

[0017] 2. The device and method of the present invention achieve cost savings, improve efficiency, and allow for the reuse of raw materials.

[0018] 3. The device of the present invention has a stable structure, is resistant to high temperature, and has high reliability, which is conducive to improving process stability and repeatability and ensuring the performance of high-end components. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the internal and external surface vapor phase co-infiltration device of the present invention.

[0020] Figure 2 This is a drawing of the frame parts of the vapor phase co-infiltration device for the inner and outer surfaces of the present invention.

[0021] Figure 3 This is a part drawing of the lifting mechanism of the inner and outer surface vapor phase co-percolation device of the present invention.

[0022] Figure 4 This is a drawing of the heating furnace parts of the vapor phase co-infiltration device for the inner and outer surfaces of the present invention.

[0023] Figure 5 This is a diagram of the reactor parts for the vapor phase co-infiltration device on the inner and outer surfaces of the present invention.

[0024] Figure 6 This is a part drawing of the bearing system of the inner and outer surface vapor phase co-infiltration device of the present invention.

[0025] Figure 7 This is a schematic diagram of the tooling structure for the inner and outer surface vapor phase co-infiltration device of the present invention.

[0026] Figure 8 This is a cross-sectional view of the tooling used in conjunction with the internal and external surface vapor phase co-infiltration device of the present invention.

[0027] Figure 9 The image shows a scanning electron microscope image of the coating thickness (20% cross-section) on the outer surface of the blade in Example 1; where: (a) point 1; (b) point 2; (c) point 3; (d) point 4; (e) point 5.

[0028] Figure 10 Images and analysis of Al content detection in the outer surface coating (20% cross-section) of the blade in Example 1 (the right image shows the element content at the corresponding point in the left image); where: (a) point 1; (b) point 2; (c) point 3.

[0029] Figure 11 Images and analysis of Al content detection in the outer surface coating (20% cross-section) of the blade in Example 1 (the right image shows the element content at the corresponding point in the left image); where: (a) point 4; (b) point 5.

[0030] Figure 12 The image shows a scanning electron microscope image of the coating thickness (80% cross-section) on the outer surface of the blade in Example 1; where: (a) point 1; (b) point 2; (c) point 3; (d) point 4; (e) point 5.

[0031] Figure 13 Images and analysis of Al content detection in the outer surface coating (80% cross-section) of the blade in Example 1 (the right image shows the element content at the corresponding point in the left image); where: (a) point 1; (b) point 2; (c) point 3.

[0032] Figure 14Images and analysis of Al content detection in the outer surface coating (80% cross-section) of the blade in Example 1 (the right image shows the element content at the corresponding point in the left image); where: (a) point 4; (b) point 5.

[0033] Figure 15 The image shows a scanning electron microscope image of the thickness of the coating (20% cross-section) inside the blade cavity in Example 1; where: (a) point 1; (b) point 2; (c) point 3; (d) point 4; (e) point 5.

[0034] Figure 16 Images and analysis of Al content detection in the inner cavity coating (20% cross-section) of the blade in Example 1 (the right image shows the element content at the corresponding point in the left image); where: (a) point 1; (b) point 2; (c) point 3.

[0035] Figure 17 Images and analysis of Al content detection in the inner cavity coating (20% cross-section) of the blade in Example 1 (the right image shows the element content at the corresponding point in the left image); where: (a) point 4; (b) point 5.

[0036] Figure 18 The image shows a scanning electron microscope image of the thickness of the coating (80% cross-section) inside the blade cavity in Example 1; where: (a) point 1; (b) point 2; (c) point 3; (d) point 4; (e) point 5.

[0037] Figure 19 Images and analysis of Al content detection in the inner cavity coating (80% cross-section) of the blade in Example 1 (the right image shows the element content at the corresponding point in the left image); where: (a) point 1; (b) point 2; (c) point 3.

[0038] Figure 20 Images and analysis of Al content detection in the inner cavity coating (80% cross-section) of the blade in Example 1 (the right image shows the element content at the corresponding point in the left image); where: (a) point 4; (b) point 5.

[0039] In the diagram: 1-Lifting mechanism, 2-Heating furnace, 3-Reaction vessel, 4-Bearing system, 5-Argon flow meter, 6-Oil-water separator, 7-Argon inlet pipe, 8-Vacuum extraction pipe, 9-Vacuum pump, 10-Main frame, 11-Exhaust pipe, 12-Vacuum ball valve, 13-Aluminizing tooling, 14-Hydraulic cylinder, 15-Insulating brick, 16-Cooling water jacket, 17-Sealing groove, 18-Workpiece loading cylinder, 19-Material trough I, 20-Annular flange, 21-Workpiece, 22-Material cylinder, 221-Material trough II, 23-Cover, 24-Interlocking device, 25-Inlet pipe; 26-Supporting platform, 27-Sealing flange II, 28-Bearing platform. Detailed Implementation

[0040] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0041] The organic binder used in the following examples was prepared by uniformly mixing polyvinyl alcohol powder (PVA2488 or PVA088-50) with deionized water at a volume ratio of 1:3. Example 1:

[0042] This invention relates to a device for simultaneous vapor-phase aluminizing of the inner cavity and outer surface of turbine blades in aero-engines or gas turbines, such as... Figure 1-8 As shown. The device includes a lifting mechanism 1, a heating furnace 2, a reaction vessel 3, a supporting system 4, a main frame 10, and an aluminizing fixture 13. The specific structure and connection relationship of each part are as follows: The main frame 10 is a vertical rectangular frame structure containing 4 columns, with adjacent columns connected by crossbeams; the lifting mechanism 1 includes a hydraulic cylinder 14 and a fixed frame, the fixed frame being a horizontal "+" shaped structure, the lower end of the hydraulic cylinder output shaft being fixed at the center of the fixed frame, and the fixed frame being fixed to the upper surface of the heating furnace body; the lifting mechanism 1 uses the 4 columns of the main frame 10 as guide supports, and the heating furnace body 2, driven by the hydraulic cylinder 14 of the lifting mechanism, achieves vertical movement along the 4 columns.

[0043] The reactor 3 is positioned directly above the supporting system 4. The reactor 3 includes a sealed pressure furnace body with a furnace cavity inside. The heating furnace 2 is fitted onto the outside of the furnace body of the reactor 3. The heating furnace includes a heating system and insulating bricks 15, used to provide a high-temperature reaction temperature field and maintain the temperature of the reactor. A cooling water jacket 16 is provided at the bottom of the furnace body of the reactor 3, and a sealing flange I is provided at the bottom of the cooling water jacket 16.

[0044] The supporting system 4 is located in the lower middle part of the main frame 10 and is supported by the main frame. The aluminizing fixture 13 is installed on the supporting system 4. The supporting system includes a support platform 26 with an inverted "U" shaped longitudinal section, a sealing flange II 27, and a cylindrical supporting platform 28. The lower ends of the vertical portions on both sides of the support platform 26 are fixed to the main frame 10, and the sealing flange II 27 is fixed to its top horizontal surface. The supporting platform 28 is fixed to the upper surface of the sealing flange II. The supporting platform has several through holes in the vertical direction for installing the aluminizing fixture 13. A sealing groove 17 is provided at the circumferential edge of the upper surface of the sealing flange II 27. A sealing ring is placed in the sealing groove for cooperation with the sealing flange I at the bottom of the cooling water jacket to achieve a seal. The bottom of the reactor is a certain distance from the top of the supporting system to facilitate operation by the operator.

[0045] The aluminizing fixture 13 includes a cover 23, a material container 22, and a workpiece loading cylinder 18. The material container 22 has a double-layer cylindrical structure, comprising an inner cylindrical body and an outer cylindrical body arranged coaxially. The outer cylindrical body is an airtight cylinder, and the inner cylindrical body is a porous cylinder made of a perforated plate. The inner cylindrical body is open at both ends, while the annular space formed between the outer and inner cylindrical bodies is a material container II 221, which is open at the top and closed at the bottom. The material container II 221 contains a vapor-phase aluminizing agent and an activator. The material container 22 is placed on top of the workpiece loading cylinder 18, and the cover 23 is located on top of the material container 22.

[0046] The workpiece loading cylinder 18 is a cylindrical structure closed at both ends, with a diamond-shaped hole on its upper surface for placing the turbine blade workpiece 21. The diamond-shaped hole on the workpiece loading cylinder 18 allows the tenon of the turbine blade to pass through, but the truss of the turbine blade cannot pass through, thus fixing the turbine blade. An upward-facing annular flange 20 is provided at the circumference (edge) of the upper surface of the workpiece loading cylinder, which can limit the position of the material container placed on the upper surface of the workpiece loading cylinder; the inner diameter of the annular flange 20 is slightly larger than the outer diameter of the material container.

[0047] The sidewall of the workpiece loading cylinder 18 has a double-layer structure. The outer layer is an airtight cylinder, and the inner layer is a porous cylinder made of a porous plate. The annular space formed between the inner and outer layers is a material trough I19, in which raw materials for vapor phase aluminizing are placed.

[0048] The aluminizing fixture also includes an air inlet pipe 25, one end of which is connected to the upper surface interface of the support system 4 (the upper surface interface and the bottom interface of the support system are connected by a pipe), and the bottom interface of the support system 4 is connected to an argon gas inlet pipe 7. This air inlet pipe 25 is used to introduce argon gas into the interior of the aluminizing fixture, bringing the aluminizing atmosphere into the workpiece cavity. A hydraulic station is connected to the argon gas inlet pipe 7 to ensure sufficient argon gas flow. The argon gas inlet pipe 7 is also equipped with an argon gas flow meter 5 and an oil-water separator 6. A 25-35° chamfer is provided on the air inlet pipe 25 at a distance of 25-35mm from the bottom surface of the workpiece loading cylinder for sealing. Each aluminizing fixture is connected to a separate argon gas inlet pipe 7 via the air inlet pipe 25.

[0049] The aluminizing tooling is made of 316 or 2520 stainless steel.

[0050] The device also includes a vacuum extraction pipe 8 and an exhaust pipe 11. One end of the vacuum extraction pipe 8 and the exhaust pipe 11 are respectively installed on the support platform and connected to the space above the support platform, and the other end is respectively connected to the vacuum pump 9 and the external ambient atmosphere; wherein: the exhaust pipe 11 is equipped with a vacuum ball valve 12 (to control the exhaust flow and close).

[0051] The method for simultaneous vapor-phase aluminizing of the inner cavity and outer surface of a blade using the aforementioned device is as follows: The support system 4 is fixed to the main frame 10, with the bottom of the support platform located 1 meter above the ground. The support system 4 is connected to a vacuum extraction pipe 8, an argon inlet pipe 7, and an exhaust pipe 11. The vacuum extraction pipe 8 and vacuum pump 9 are used to extract impurities from the reactor before the process to prevent oxidation of the workpiece at high temperatures. The argon inlet pipe 7 is connected to an oil-water separator 6, which filters oil and water vapor that may be present in the argon pipeline to ensure the purity of the argon. The oil-water separator 6 is connected to an argon flow meter 5 to control the argon flow rate. The exhaust pipe 11 is connected to a vacuum ball valve 12 at the bottom of the support system 4. The vacuum ball valve 12 must be closed when venting impurities from the reactor in the early stage of the process, and kept open from the beginning to the end of the process. Several [unclear text - possibly related to a product or service] are placed on top of the support platform. Figure 7 The tooling 13 shown is used to first place the raw materials required for vapor phase aluminizing into the material storage tank I 19 inside the workpiece loading cylinder 18 of the tooling 13; place the workpiece into the opening on the upper surface of the workpiece loading cylinder 18, and then place the lower end of the material storage cylinder into the annular protrusion 20 on the upper surface of the workpiece loading cylinder, and place the raw materials required for vapor phase aluminizing into the material storage tank II 221; cover the material storage tank II with the cover plate 23; the lifting mechanism 1 is placed above the main frame 10, and the lifting mechanism controls the lifting of the heating furnace 2 and the reactor 3 through the hydraulic cylinder 14. The lifting of the heating furnace 2 can be controlled separately or simultaneously by the interlocking device 24. The heating furnace 2 is equipped with heat-insulating bricks 15 for high-temperature heat preservation. The bottom of the reactor 3 is equipped with a cooling water jacket 16, which is connected to external cooling water to prevent the sealing ring in the sealing groove 17 from deforming at high temperature. The hydraulic cylinder 14 is used to lower the heating furnace 2 and the reactor 3 to the bearing system 4, so that the bottom sealing flange I of the cooling water jacket 16 seals with the sealing groove 17.

[0052] The specific operating steps of the device of the present invention are as follows: The supporting system is placed on the main frame 1 meter above the ground. The lifting mechanism raises the heating furnace and the reactor, and the tooling is placed in the through hole above the supporting system. The workpiece is placed with its tenon facing down in the diamond-shaped hole on the workpiece loading cylinder of the tooling. The raw materials required for vapor phase aluminizing are placed in the material storage tank I (in the workpiece loading cylinder) and the material storage tank II (in the material storage cylinder) to ensure sufficient aluminum atmosphere is generated at high temperature. After the aluminizing tooling is placed in the through hole above the supporting system, the lifting mechanism is used to lower the heating furnace and the reactor, so that the bottom sealing flange I of the reactor and the bottom sealing flange II of the supporting system are fitted and sealed. The vacuum pump is turned on to replace the impurity gas in the reactor furnace. First, the vacuum pump is used to evacuate the gas in the furnace to a pressure of -100 kPa. 99.999% high-purity argon is introduced into the furnace at a flow rate of 3 L / min to a pressure of +1 kPa. The vacuum pump is then turned on again to continue evacuating the gas. This operation is repeated 3 times. When argon is introduced to +1 kPa for the last time, the vacuum ball valve on the exhaust pipe is opened to exhaust the gas, and argon is continuously introduced at 3 L / min as an inert protective gas to ensure that the workpiece and tooling inside the reactor are not oxidized. After the impurity gas is vented, the heating system is turned on to raise the temperature to 950-1100℃ and hold it for 120-240 min (the specific temperature and time need to be confirmed according to the workpiece). During the heating process, the inner cavity and outer surface of the workpiece have been prepared with an aluminized coating. The principle is as follows: the argon flow rate in the argon inlet pipe connected to the bearing system is set to 3 L / min, so that the argon acts as a carrier gas to carry the aluminum atmosphere from the tenon to the inner cavity flow channel of the workpiece, thereby completing the preparation of the aluminized coating in the inner cavity. After the preparation of the aluminized coating in the inner cavity and outer surface is completed, the interlock device 24 is opened to lift the heating furnace separately and cool it to room temperature. Then, the heating furnace is lowered to the bottom, the interlock device is closed, and the reactor and heating furnace are lifted together to remove the workpiece.

[0053] The method for simultaneously preparing high-temperature protective aluminized coatings on the inner cavity and outer surface of a workpiece using the apparatus of the present invention is as follows: 1. In the process preparation stage: Place the raw materials required for aluminizing into the material storage trough I of the workpiece loading cylinder 18 of the aluminizing tooling, place the workpiece with the tenon facing down into the hole on the upper surface of the workpiece loading cylinder 18, fill the material storage trough II 221 with the raw materials required for aluminizing, place the material storage cylinder 22 into the annular protrusion 20 on the upper surface of the workpiece loading cylinder 18, and finally cover the material storage trough II 221 with the cover body 23.

[0054] 2. Gas replacement stage: Use the lifting mechanism to lower the heating furnace 2 and the reaction vessel 3 to the sealing groove 17 of the support system 4, close the vacuum ball valve 12, turn on the vacuum pump 9, and discharge the impurity gas in the reaction vessel 3 through the vacuum pumping pipe 8. After purging, introduce argon gas through the argon gas inlet pipe 7. Repeat the "gas discharge and gas introduction" process three times. After the last argon gas introduction is completed, open the exhaust vacuum ball valve 12 to ensure the continuous flow of argon gas.

[0055] 3. Heating stage: Set the temperature to the corresponding process requirement temperature, start the heating furnace 2 to heat up, and introduce cooling water into the cooling water jacket 16.

[0056] 4. Vapor phase aluminizing process: During the heating and holding stages, the raw materials (aluminum blocks and activators) in the material tank I and material tank II continuously generate new aluminum atmosphere. At the same time, argon gas enters the aluminizing fixture through the argon gas inlet pipe 7. The aluminum atmosphere in the material tank I is first brought into the inner cavity flow channel through the tenon inlet of the workpiece 21 to prepare the inner cavity coating. The excess aluminum atmosphere flows out through the exhaust edge or gas film hole of the workpiece 4 to prepare the coating on the outer surface of the workpiece 21. At the same time, the aluminum atmosphere in the material tank II also adheres to the outer surface of the workpiece 21 to prepare the aluminizing coating on the outer surface.

[0057] 5. Process completion: Turn off the argon gas and vacuum ball valve 12, and allow the temperature to drop.

[0058] Example 1: This embodiment describes the simultaneous preparation of an aluminizing coating on the inner cavity and outer surface of a gas turbine blade. The blade's inner cavity is a cross-flow channel, and the blade body does not have film cooling holes. Specific technical requirements are as follows: (1) The coating thickness of the inner cavity flow channel is required to be 15-45 micrometers, and the coating thickness of the outer surface is required to be 20-64 micrometers.

[0059] (2) The Al content in the inner cavity flow channel coating is required to be 15-28wt%, and the Al content in the outer surface coating is required to be 15-28wt%.

[0060] Based on the above technical requirements and the application case of this device, the process parameters are set as follows: heat up to 1050℃ and hold for 240 min, argon gas inlet flow rate 2L / min.

[0061] The specific process for preparing the aluminized coating in this embodiment is as follows: 1. Blade Pretreatment: Observe the outer surface of the blade for scratches or dents using a magnifying glass and stereomicroscope. Observe the internal flow channels for foreign objects that may affect the preparation of the inner cavity infiltration layer using an endoscope. Protect the uncoated areas with 3M masking tape. Sandblast the infiltration layer areas with 180-mesh white corundum at a sandblasting pressure of (4.5±1.0) kg / cm². 2After sandblasting, the parts are placed in an ultrasonic machine for ultrasonic treatment to remove the remaining sand particles in the inner cavity. The ultrasonic treatment time is (30±10) min. After ultrasonic treatment, deionized water is used to test the water flow in the inner cavity and to check for any foreign matter residue in the inner cavity. The blades are then placed in a drying oven to dry at a temperature of (150±10) ℃ for a time of (30±10) min.

[0062] 2. Protection of uncoated areas: Protect the uncoated areas with protective slurry. Place the protected blade with the tenon facing down into the hole on the upper surface of the workpiece loading cylinder 18. Put 2kg of aluminum block and 5g of activator into the material tank I and 3.5kg of aluminum block and 8g of activator into the material tank II to generate the atmosphere for diffusion layer preparation.

[0063] 3. Vapor phase aluminizing of inner cavity and outer surface: The process parameters are set as follows: 1050℃ / 240min, argon gas flow rate 2L / min.

[0064] 4. Post-penetration cleaning: Remove the protective powder from the non-coated areas using compressed air, place the area in an ultrasonic cleaner for cleaning the inner cavity and outer surface, ultrasonic time (30±10) min, place the blade in a drying oven to dry at a temperature of (150±10) ℃ for a time of (30±10) min.

[0065] 5. Infiltration Layer Inspection: As required, take sections at 20% and 80% of the leaf height to measure the thickness and elemental content of the inner cavity and outer surface. Measure five points on each of the inner and outer surfaces using a scanning electron microscope (SEM) at a 500X field of view. Measure the thickness four times at each point, and select three fields of view (spectral density) for elemental content measurement. Figure 1 Spectrum Figure 2 Spectrum Figure 3 ), comprising inner and outer layers, the test results are as follows Figures 9-20 And Tables 1-4, where: In Table 1, the 20% cross-section refers to the selected points on the outer surface coating at 20% of the blade height from bottom to top, and the 80% cross-section refers to the selected points on the outer surface coating at 80% of the blade height from bottom to top; points 1-4 in Table 2 correspond to points 1-4 in Table 1. In Table 3, the 20% cross-section refers to the selected points on the inner surface coating at 20% of the blade height from bottom to top, and the 80% cross-section refers to the selected points on the inner surface coating at 80% of the blade height from bottom to top; points 1-4 in Table 4 correspond to points 1-4 in Table 3.

[0066] Table 1. Results of coating thickness test on the outer surface of the blades Table 2. Detection results of aluminum content in the outer surface coating of the blades. Table 3. Results of coating thickness test in blade inner cavity Table 4. Detection results of aluminum content in the inner coating of the blade. The conclusions drawn from testing the blades according to the relevant technical requirements after coating preparation in this embodiment are as follows: 1. The coating thickness of the blade's inner cavity and outer surface meets the technical requirements: the coating thickness of the inner cavity flow channel should be 15-45 micrometers, and the coating thickness of the outer surface should be 20-64 micrometers. 2. The Al content in the inner cavity and outer surface coating of the blade meets the technical requirements: the Al content in the inner cavity flow channel coating is required to be 15-28wt%, and the Al content in the outer surface coating is required to be 15-28wt%.

[0067] Analysis of the apparatus and method for preparing aluminized coatings on the inner cavity and outer surface of blades according to the present invention, and its application cases, yields the following results: 1. This device can meet the requirement of preparing aluminized coatings on both the inner and outer surfaces.

[0068] 2. This process is effective and feasible, reducing the heat treatment required for preparing two coatings on the blades and improving the blade performance. Moreover, this process can be applied to production, solving the problems of difficult cleaning, uneven coating, and high cost of powder embedding and slurry methods. Its production efficiency far exceeds that of the two processes mentioned above.

[0069] 3. Compared with CVD chemical vapor deposition equipment, this device has a simple structure, reasonable manufacturing cost, and the detection results after coating preparation are basically consistent with CVD. It can be applied to the preparation of infiltration layers for turbine blades of aero-engines and gas turbines.

[0070] The above description is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An apparatus for simultaneously preparing a high-temperature protective aluminized coating on the inner cavity and outer surface of a workpiece, characterized in that: The device includes a lifting mechanism, a heating furnace, a reaction vessel, a supporting system, a main frame, and an aluminizing fixture. The main frame is a vertical frame structure. The supporting system is located in the lower middle part of the main frame and supported by the main frame. The aluminizing fixture is mounted on the supporting system. The reaction vessel is located directly above the supporting system. The heating furnace is fitted around the outside of the reaction vessel to provide external heating. The lifting mechanism is fixed to the heating furnace and controls the lifting and lowering of the heating furnace and the reaction vessel.

2. The apparatus for simultaneously preparing high-temperature protective aluminized coatings on the inner cavity and outer surface of a workpiece according to claim 1, characterized in that: The reactor includes a sealed pressure furnace body, with a furnace cavity formed inside. A cooling water jacket is provided at the bottom of the furnace body, and a sealing flange I is provided at the bottom of the cooling water jacket for cooperation with a sealing flange II in the support system to form a seal. The bottom of the reactor is a certain distance from the top of the support system to facilitate operation by the operator. The heating furnace is equipped with heating elements and heat-insulating brick material to provide a high-temperature reaction temperature field for the reactor and maintain the temperature. The heating furnace is fitted onto the outside of the furnace body of the reactor.

3. The apparatus for simultaneously preparing a high-temperature protective aluminized coating on the inner cavity and outer surface of a workpiece according to claim 1 or 2, characterized in that: The load-bearing system includes a support platform with an inverted "U" shaped longitudinal section, a sealing flange II, and a cylindrical load-bearing platform. The lower ends of the vertical portions on both sides of the support platform are fixed to the main frame, and the sealing flange II is fixed to its top horizontal surface. The load-bearing platform is fixed to the sealing flange II. Several through holes are provided in the vertical direction on the load-bearing platform for installing the aluminizing tooling. A sealing groove is provided at the circumferential edge of the upper surface of the sealing flange II, and a sealing ring is placed in the sealing groove for sealing with the sealing flange I.

4. The apparatus for simultaneously preparing a high-temperature protective aluminizing coating on the inner cavity and outer surface of a workpiece according to claim 1 or 3, characterized in that: The aluminizing fixture includes a cover, a material holding cylinder, and a workpiece loading cylinder. The material holding cylinder is placed on top of the workpiece loading cylinder, and the cover is located on the top of the material holding cylinder. The workpiece loading cylinder is a cylindrical structure closed at both ends, and a diamond-shaped hole is opened on its upper surface for placing turbine blades. The material container is a double-layer cylindrical structure, including an inner cylindrical body and an outer cylindrical body arranged coaxially. The outer cylindrical body is an airtight cylinder, and the inner cylindrical body is a porous cylinder made of a porous plate. The inner cylindrical body is open at both ends, and the annular space formed between the outer and inner cylindrical bodies is a material container II, which is open at the top and closed at the bottom. The material container II contains the raw materials used for vapor phase aluminizing.

5. The apparatus for simultaneously preparing high-temperature protective aluminizing coatings on the inner cavity and outer surface of a workpiece according to claim 4, characterized in that: In the aluminizing tooling, an upward-facing annular protrusion is provided at the circumferential position (edge) of the upper surface of the workpiece loading cylinder, which can limit the material holding cylinder placed on the upper surface of the workpiece loading cylinder; the inner diameter of the annular protrusion is slightly larger than the outer diameter of the material holding cylinder. The diamond-shaped holes on the upper surface of the workpiece loading cylinder allow the tenon of the turbine blade to pass through, but the truss of the turbine blade cannot pass through, thereby fixing the turbine blade. The sidewall of the workpiece loading cylinder has a double-layer structure. The outer layer is an airtight cylinder, and the inner layer is a porous cylinder made of a perforated plate. The annular space formed between the inner and outer layers is a material storage tank I, in which raw materials for vapor phase aluminizing are placed.

6. The apparatus for simultaneously preparing high-temperature protective aluminized coatings on the inner cavity and outer surface of a workpiece according to claim 4, characterized in that: The aluminizing fixture also includes an air inlet pipe. One end of the air inlet pipe is fixed to the center of the bottom surface of the workpiece loading cylinder and is connected to the inside of the workpiece loading cylinder. The other end is connected to an argon gas inlet pipe. The air inlet pipe is used to introduce argon gas into the interior of the aluminizing fixture (the inside of the workpiece loading cylinder and the inside of the material container). An argon gas cylinder is connected to the argon gas inlet pipe. An argon gas flow meter and an oil-water separator are also provided on the argon gas inlet pipe near the argon gas cylinder. A 25-35° chamfer is provided on the air inlet pipe 25-35mm away from the bottom surface of the workpiece loading cylinder for sealing.

7. The apparatus for simultaneously preparing high-temperature protective aluminized coatings on the inner cavity and outer surface of a workpiece according to claim 4, characterized in that: The aluminizing tooling is made of 316 stainless steel or 2520 stainless steel.

8. The apparatus for simultaneously preparing high-temperature protective aluminizing coatings on the inner cavity and outer surface of a workpiece according to claim 1, characterized in that: The main frame is a rectangular frame structure containing four columns, with adjacent columns connected by crossbeams. The lifting mechanism includes a hydraulic cylinder and a fixed frame. The fixed frame is a horizontal "+" shaped structure, with the lower end of the hydraulic cylinder output shaft fixed at the center of the fixed frame. The fixed frame is fixed to the upper surface of the heating furnace body. The lifting mechanism uses the four columns of the main frame as guide supports, and the heating furnace body moves vertically along the four columns under the drive of the hydraulic cylinder of the lifting mechanism.

9. The apparatus for simultaneously preparing high-temperature protective aluminized coatings on the inner cavity and outer surface of a workpiece according to claim 1, characterized in that: The device also includes a vacuum extraction pipe and an exhaust pipe. One end of the vacuum extraction pipe and the exhaust pipe are respectively installed on the support platform and connected to the space above the support platform, and the other end is respectively connected to the vacuum pump and the external atmosphere. Among them, the exhaust pipe is equipped with a vacuum ball valve (to control the exhaust flow and close).

10. A method for simultaneously preparing a high-temperature protective aluminizing coating on the inner cavity and outer surface of a workpiece using the apparatus described in any one of claims 1-9, characterized in that: This method utilizes the aforementioned device, as detailed below: The supporting system is placed on the main frame 1 meter above the ground. The lifting mechanism raises the heating furnace and the reactor, and the tooling is placed at the through hole above the supporting system. The workpiece is placed with its tenon facing down in the diamond-shaped hole on the workpiece loading cylinder of the tooling. Raw materials for vapor phase aluminizing are placed in the material storage tank I (in the workpiece loading cylinder) and the material storage tank II (in the material storage cylinder) to ensure sufficient aluminum atmosphere is generated at high temperature. After the tooling is placed at the through hole above the supporting system, the lifting mechanism is used to lower the heating furnace and the reactor, so that the bottom sealing flange I of the reactor and the bottom sealing flange II of the supporting system are fitted and sealed. The vacuum pump is turned on to replace the impurity gas in the reactor furnace. First, the vacuum pump is used to evacuate the furnace and the pressure is emptied to -100KPa. High-purity argon is introduced into the furnace through each argon inlet pipe at a flow rate of 3L / min until the pressure reaches +1KPa, and then the vacuum pump is turned on. The pump continues to evacuate, repeating this operation three times. During the final evacuation, when argon gas is introduced to +1 kPa, the vacuum ball valve on the exhaust pipe is opened to vent the gas. Argon gas is continuously introduced at a flow rate of 3 L / min as an inert protective gas to ensure that the workpiece and tooling inside the reactor are not oxidized. After the impurity gas is vented, the heating system is turned on to raise the temperature to 950-1100℃ and held for 120-240 minutes. During the heating process, an aluminized coating is prepared on the inner cavity and outer surface of the workpiece. The aluminizing principle is as follows: the argon gas flow rate in the argon gas inlet pipe connected to the support system is set to 3 L / min, allowing argon gas to carry the aluminum atmosphere from the tenon teeth into the inner cavity flow channel, thus completing the preparation of the aluminized coating in the inner cavity. After the aluminized coatings on the inner cavity and outer surface are completed, the heating furnace is raised and cooled to room temperature, and then the reactor is raised to remove the workpiece.

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