Process for chemical vapor deposition of multi-component diffusion metalized layers

Abstract

The application discloses a process method for chemical vapor deposition of multi-element permeation metal layer, and belongs to the technical field of heat treatment. The process method comprises the following steps: preparing special gas guide tooling, and assembling the tooling to form a one-way gas path which is discharged from a blade tenon into an inner cavity and through a blade air film hole; after filling of an aluminum-chromium-silicon generator permeation agent is completed, the blade is sandblasted, cleaned and purged, the butt joint tooling pipeline is mounted and fixed in a reaction chamber; after the reaction chamber is heated to a reaction temperature, Ar and HCl are introduced into an internal Cr generator, and a chromium layer is formed under a low-pressure environment; H2+HCl is introduced to complete chromium-aluminum co-permeation; the temperature is lowered to a silicon permeation process temperature, H2+Ar carrier gas is introduced to complete silicon co-permeation, and a chromium-aluminum-silicon multi-element permeation layer is formed on the inner cavity and the outer surface of the blade; after the permeation agent reaction is completed, H2 is introduced to lower the temperature, inert gas is switched below 500 DEG C to cool the blade to 100 DEG C, and the blade is taken out of the furnace, and finally, vacuum diffusion annealing is carried out. The permeation layer is uniform and is not limited by the shape and structure of the workpiece, and the process has strong adaptability.

Description

Technical Field

[0001] This invention belongs to the field of heat treatment technology, specifically relating to a process method for chemical vapor deposition of multi-element co-diffusion metal diffusion layers. Background Technology

[0002] Hollow air-cooled blades are a core technology for achieving high turbine inlet gas temperatures and improving overall thrust and thermal efficiency in aero-engines. By rationally designing the internal structure of the hollow blade and employing appropriate cooling technologies, high-temperature alloys can withstand even higher gas temperatures. However, the cooling channels within the hollow blade cavity operate at temperatures exceeding 900°C for extended periods, making them highly susceptible to high-temperature oxidation and thermal corrosion failures. These are key factors limiting the service life and reliability of hollow air-cooled blades. Therefore, implementing efficient protective treatment on the blade's internal surface is crucial for extending its overall service life and ensuring stable engine operation.

[0003] Multi-element metal diffusion layers (Al-Cr-Si co-diffusion metal diffusion layers) possess excellent high-temperature oxidation and hot corrosion resistance properties, potentially significantly improving the high-temperature protection performance of component surfaces, making them a mainstream surface strengthening technology for aerospace high-temperature components. Currently, the main processes for preparing Al-Cr-Si multi-element diffusion layers include slurry methods, powder methods, and chemical vapor deposition (CVD). However, for the complex internal cavities of hollow blades, slurry and powder methods are prone to problems such as pore blockage and difficulty in cleaning residual diffusion agent within the cavity, resulting in poor processing yield and process adaptability. Conventional CVD processes suffer from the technical bottleneck of thermodynamic mismatch in the deposition of various elements, making it impossible to achieve efficient, simultaneous, and uniform precipitation of aluminum, chromium, and silicon within the same reaction system, ultimately leading to uneven diffusion layer composition and poor process controllability.

[0004] To address the technical challenges of poor controllability of traditional preparation processes, difficulty in cleaning residual infiltrator in the inner cavity, and uneven composition of the infiltrated layer, there is an urgent need to develop a gas-phase multi-metal infiltrated layer preparation process that can adapt to the needs of preparing integrated multi-element infiltrated layers for the inner cavity and outer surface of complex-shaped hollow blades. Summary of the Invention

[0005] To address the problems existing in the prior art, the present invention aims to provide a process method for chemical vapor deposition of multi-element co-diffusion metal diffusion layers for the preparation of multi-element metal diffusion layers on the inner cavity and outer surface of complex cavity hollow blades. This method achieves the formation of continuous multi-element co-diffusion metal diffusion layers on the inner cavity and cooling channels of the blades, with the diffusion layer thickness on the inner cavity and outer surface being basically uniform, thereby effectively improving the high-temperature protection capability of the blade surface and extending the service life of the parts.

[0006] This invention provides a process for chemical vapor deposition of a multi-element co-diffusion metal layer, comprising the following steps: (1) Preparation of special gas guiding tooling: The blade gas guide fixture mainly includes an aluminized frame, a lower shell, and a top cover. The aluminized frame chassis has a large hole in the center that connects to the gas guide holes of the internal Al generator and the internal Cr generator. Several small gas guide holes are evenly distributed on the surface of the aluminized frame chassis. The shape and size of the lower shell and the top cover are designed to match the dimensions of the turbine blade tenon and blade tip structure to ensure that the fixture fits tightly with the blade and reduce the gas flow rate in the fit gap. (2) Preparation for filling process infiltration agent: Bright aluminum particles were loaded into the external Al generator and the internal Al generator respectively, chromium particles were loaded into the internal Cr generator, and liquid SiCl4 was loaded into the Si generator. (3) Blade pretreatment: The surfaces of the parts to be infiltrated and the matching test pieces are pretreated by using a liquid sandblasting machine to remove oxide scale and other adhering substances from the surface of the parts; then they are cleaned and blew. (4) Workpiece mounting and fixing: The pre-treated blades are installed on a special gas guiding fixture. The blade tenons are fixed inside the lower shell. The gas guiding pipe on the lower shell is precisely connected to the small gas guiding hole of the aluminized frame chassis. The blade tip is sealed by the upper cover to build a dedicated gas flow channel. The internal Al generator and the special gas guiding fixture with assembled blades are installed and fixed in the corresponding positions of the reaction chamber in sequence, and the clamping is firm and stable. (5) Chromium-aluminum co-diffusion treatment: The external Al generator and reaction chamber are heated simultaneously. During the heating process, H2 is continuously introduced into the external Al generator and reaction chamber. After the external Al generator reaches the preset temperature, HCl gas is introduced. After the reaction chamber is heated to the chromium-aluminum co-diffusion process temperature, Ar gas is introduced into the reaction chamber, and HCl gas is introduced into the internal Cr generator for a preset duration. Under low pressure, a chromium layer or a chromium-rich layer is formed on the surface of the workpiece. Then, the H2+HCl aluminizing active gas generated by the external Al generator is introduced into the surface of the workpiece in the reaction chamber through the internal Al generator, and a chromium-rich aluminum diffusion layer is generated simultaneously in the inner cavity and outer surface of the blade. After the chromium-aluminum co-diffusion deposition is completed, the heating of the external Al generator and reaction chamber is stopped, the introduction of HCl gas into the Al generator is stopped, and H2 gas is continuously introduced. (6) Silicon co-infiltration treatment: After the reaction chamber cools down to the silicon diffusion process temperature, stop supplying H2 to the external Al generator, maintain the silicon diffusion process temperature in the reaction chamber, and supply H2 to the Si generator so that it mixes with the H2 and Ar carrier gas in the main gas pipeline in the mixing chamber to form a silicon-rich active gas. The active gas enters the reaction chamber with the carrier gas and forms a chromium-aluminum-silicon multi-metal diffusion layer in the inner cavity and outer surface of the blade. (7) Cooling by displacement: After the silicon infiltration process is completed, stop heating the reaction chamber and supplying H2 to the Si generator, stop the Ar gas inlet in the main pipeline and continue to supply H2; when the reactor temperature drops below 500℃, replace the gas inlet with H2 and inert gas, and remove the reactor when the temperature reaches 100℃. The co-infiltrated blades are then cooled to room temperature. (8) Post-processing: Vacuum diffusion annealing is performed on the blades with multi-element co-diffusion metal infiltration layers after cooling, so that a complete, continuous and dense multi-element co-diffusion metal infiltration layer is formed on the inner cavity and outer surface of the blades.

[0007] Further, in step (1), the gas guide pipe on the lower shell is connected to the small gas guide holes distributed on the aluminized frame chassis; after the tooling is assembled, a one-way gas flow path is formed by the large central hole of the aluminized frame chassis, the small gas guide holes of the chassis, the gas guide pipe of the lower shell, the inner cavity of the blade, and the gas film hole of the blade body, so that the reaction gas enters the inner cavity from the blade tenon and exits from the gas film hole of the blade body.

[0008] Furthermore, in step (2), based on the furnace loading amount, target infiltration layer thickness, chemical composition, infiltration layer preparation temperature and time, the loading amount of each infiltration agent and the parameters for introducing HCl, hydrogen and Ar gas are matched and determined to ensure a continuous and sufficient supply of infiltration agent.

[0009] Furthermore, in step (3), the particle size of the corundum sand used in the liquid sand blowing machine is 120 mesh to 220 mesh, and the working pressure is 0.2 MPa to 0.5 MPa; the cleaning method is centrifugal cleaning, and the blowing method is high-pressure blowing.

[0010] Furthermore, in step (4), the reaction gas in the dedicated gas flow channel enters the center of the chassis through the central air guide hole of the aluminized frame, and then flows into the lower shell through the small air guide hole on the chassis. That is, the reaction gas enters the inner cavity of the blade from the blade tenon and finally exhausts from the air film hole of the blade body to form a flowable atmosphere.

[0011] Further, in step (5), the preset temperature is 200℃~400℃, the chromium-aluminum co-diffusion process temperature is heated to 900℃~1100℃, H2 and HCl gases are introduced into the external Al generator, the H2 flow rate is 15L / min~35L / min, the HCl flow rate is 1L / min~2.5L / min; the Ar gas flow rate introduced into the reaction chamber is 10L / min~30L / min; the preset duration of HCl gas introduced into the internal Cr generator is 60min~120min, and the HCl gas flow rate is 2L / min~5L / min.

[0012] Furthermore, in step (5), the total deposition time of the chromium-aluminum co-diffusion treatment is 100 min to 180 min, and the pressure in the reaction chamber is 150 mbar to 250 mbar.

[0013] Furthermore, in step (6), the silicon diffusion process temperature is 880℃~950℃; the flow rate of H2 introduced into the Si generator is 0.5L / min~0.8L / min; and the flow rates of H2 and Ar in the silicon-rich active gas are both 15L / min. The deposition time for silicon co-diffusion treatment is 50 min to 100 min, and the pressure in the reaction chamber is 150 mbar to 250 mbar.

[0014] Furthermore, in step (7), the flow rate of H2 continuously introduced is 20L / min to 30L / min.

[0015] Furthermore, in step (8), the annealing temperature of the vacuum diffusion annealing treatment is 950℃~1050℃, and the holding time is 2h~3h; In the multi-element co-diffusion metal infiltration layer, the mass fraction of aluminum can be controlled within the range of 18% to 30%, the mass fraction of silicon can be controlled within the range of 3% to 6%, and the mass fraction of chromium can be controlled within the range of 3% to 5%.

[0016] Advantages and effects of the present invention: 1. The process of this invention can prepare a complete, continuous and dense aluminum-chromium-silicon multi-element infiltration layer on the inner cavity and outer surface of the blade, and simultaneously obtain a multi-element infiltration layer with high uniformity, basically consistent thickness and excellent protective performance on the inner cavity cooling channel and outer surface.

[0017] 2. The process method of the present invention is not limited by the shape and structure of the workpiece, and has strong process adaptability.

[0018] 3. The process method of this invention effectively solves the problems of pore blockage and difficult cleaning of the aluminizing agent in traditional aluminizing silicon and chromium aluminizing processes.

[0019] 4. The raw material cost required by the process method of the present invention is low, the process is simple, and the production efficiency is high.

[0020] 5. The process method of the present invention can precisely control the element content of the diffusion layer. The mass fraction of aluminum can be controlled within the range of 18% to 30%, the mass fraction of silicon can be controlled within the range of 3% to 6%, and the mass fraction of chromium can be controlled within the range of 3% to 5%. Attached Figure Description

[0021] Figure 1 This is a scanning electron microscope (SEM) image of the multi-element co-diffusion metal diffusion layer formed in Embodiment 1 of the present invention. Detailed Implementation

[0022] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples.

[0023] This invention provides a process for chemical vapor deposition of a multi-element co-diffusion metal layer, comprising the following steps: (1) Preparation of special gas guiding tooling: The blade gas guiding fixture mainly includes an aluminizing frame, a lower shell, and a top cover. The aluminizing frame chassis has a large hole in the center that connects to the gas guide holes of the internal Al generator and the internal Cr generator. Several small gas guide holes are evenly distributed on the surface of the aluminizing frame chassis. The gas guide pipe on the lower shell is connected to the small gas guide holes distributed on the aluminizing frame chassis. The shape and size of the lower shell and the top cover are designed to match the dimensions of the turbine blade tenon and blade tip structure to ensure that the fixture fits tightly with the blade and reduce the gas flow through the fit gap. After the fixture is assembled, it forms a unidirectional gas flow path consisting of the large hole in the center of the aluminizing frame chassis, the small gas guide holes in the chassis, the gas guide pipe in the lower shell, the blade inner cavity, and the blade body gas film vents, allowing the reacting gas to enter the inner cavity from the blade tenon and exit from the blade body gas film vents.

[0024] (2) Preparation for filling process infiltration agent: Bright aluminum particles are loaded into the external Al generator and the internal Al generator respectively, chromium particles are loaded into the internal Cr generator, and liquid SiCl4 is loaded into the Si generator. Based on the furnace loading amount, target diffusion layer thickness, chemical composition, diffusion layer preparation temperature and time, the loading amount of each diffusion agent and the introduction parameters of HCl, hydrogen and Ar gas are matched and determined to ensure a continuous and sufficient supply of diffusion agents.

[0025] (3) Blade pretreatment: The surfaces of the parts to be infiltrated and the matching test pieces are pretreated by using a liquid sandblasting machine to remove the oxide scale and other adhering substances from the surface of the parts. The corundum sand used in the liquid sandblasting machine has a particle size of 120-220 mesh and a working pressure of 0.2MPa-0.5MPa. Then, centrifugal cleaning is performed, followed by high-pressure purging.

[0026] (4) Workpiece mounting and fixing: The pretreated blades are installed on a special gas guiding fixture. The blade tenons are fixed inside the lower housing. The gas guiding pipe on the lower housing is precisely connected to the small gas guiding hole on the aluminizing frame chassis. The blade tip is sealed by the upper cover to create a dedicated gas flow channel. The reaction gas enters the center of the chassis through the central gas guiding hole of the aluminizing frame, and then flows into the lower housing through the small gas guiding hole on the chassis. That is, the reaction gas enters the blade cavity from the blade tenon and finally exhausts from the gas film hole on the blade body to form a flowing atmosphere. The internal Al generator and the special gas guiding fixture with the assembled blades are installed and fixed in sequence at the corresponding positions in the reaction chamber, and the clamping is firm and stable.

[0027] (5) Chromium-aluminum co-diffusion treatment: The external Al generator and reaction chamber are heated simultaneously. During the heating process, H2 is continuously introduced into the external Al generator and reaction chamber at a rate of 15 L / min to 35 L / min. After the external Al generator reaches 200℃ to 400℃, HCl gas is introduced at a rate of 1 L / min to 2.5 L / min. When the reaction chamber reaches 900℃ to 1100℃, Ar gas is introduced into the reaction chamber at a rate of 10 L / min to 30 L / min, while HCl gas is introduced into the internal Cr generator for a preset duration of 60 min to 120 min at a flow rate of 2 L / min. The flow rate is 5 L / min to 5 L / min, under low pressure, to form a chromium layer or a chromium-rich layer on the workpiece surface. Then, the H2+HCl aluminizing active gas generated by the external Al generator is introduced into the workpiece surface in the reaction chamber through the internal Al generator, and a chromium-rich aluminum aluminizing layer is generated simultaneously in the inner cavity and outer surface of the blade. The total deposition time for this step is 100 min to 180 min, and the pressure in the reaction chamber is 150 mbar to 250 mbar. After the chromium-aluminum co-diffusion deposition is completed, the external Al generator and the reaction chamber are stopped heating, the HCl gas is stopped being supplied to the Al generator, and H2 gas is continuously supplied.

[0028] (6) Silicon co-infiltration treatment: After the reaction chamber cools down to 880℃~950℃, stop supplying H2 to the external Al generator and maintain the silicon diffusion process temperature in the reaction chamber. Then, supply H2 at a rate of 0.5L / min~0.8L / min to the Si generator, so that it mixes with the H2 and Ar carrier gas in the main gas pipeline in the mixing chamber to form a silicon-rich active gas. The flow rates of H2 and Ar in the silicon-rich active gas are both 15L / min. They enter the reaction chamber with the carrier gas and form a chromium-aluminum-silicon multi-metal diffusion layer on the inner cavity and outer surface of the blade. The deposition time is 50min~100min, and the pressure in the reaction chamber is 150mbar~250mbar.

[0029] (7) Cooling by displacement: After the silicon infiltration process is completed, stop heating the reaction chamber and supplying H2 to the Si generator, stop the Ar gas inlet in the main pipeline, and continuously introduce H2 at a rate of 20 L / min to 30 L / min. When the reactor temperature drops below 500°C, replace the introduced gas with an inert gas. After reaching 100°C, remove the reactor and cool the co-infiltrated blades to room temperature.

[0030] (8) Post-processing: The blades with multi-element co-diffusion metal infiltration layers after cooling are subjected to vacuum diffusion annealing treatment at a temperature of 950℃~1050℃ and a holding time of 2h~3h, so that a complete, continuous and dense multi-element co-diffusion metal infiltration layer is formed on the inner cavity and outer surface of the blade. The mass fraction of aluminum is controllable within the range of 18%~30%, the mass fraction of silicon is controllable within the range of 3%~6%, and the mass fraction of chromium is controllable within the range of 3%~5%.

[0031] Example 1 A process for chemical vapor deposition of a multi-element co-diffusion metal diffusion layer includes the following steps: (1) Preparation of special gas guiding tooling: The blade gas guiding fixture mainly includes an aluminizing frame, a lower shell, and a top cover. The aluminizing frame chassis has a large hole in the center that connects to the gas guide holes of the internal Al generator and the internal Cr generator. Several small gas guide holes are evenly distributed on the surface of the aluminizing frame chassis. The gas guide pipe on the lower shell is connected to the small gas guide holes distributed on the aluminizing frame chassis. The shape and size of the lower shell and the top cover are designed to match the dimensions of the turbine blade tenon and blade tip structure to ensure that the fixture fits tightly with the blade and reduce the gas flow through the fit gap. After the fixture is assembled, it forms a unidirectional gas flow path consisting of the large hole in the center of the aluminizing frame chassis, the small gas guide holes in the chassis, the gas guide pipe in the lower shell, the blade inner cavity, and the blade body gas film vents, allowing the reacting gas to enter the inner cavity from the blade tenon and exit from the blade body gas film vents.

[0032] (2) Preparation for filling process infiltration agent: Bright aluminum particles are loaded into the external Al generator and the internal Al generator respectively, chromium particles are loaded into the internal Cr generator, and liquid SiCl4 is loaded into the Si generator. Based on the furnace loading amount, target diffusion layer thickness, chemical composition, diffusion layer preparation temperature and time, the loading amount of each diffusion agent and the introduction parameters of HCl, hydrogen and Ar gas are matched and determined to ensure a continuous and sufficient supply of diffusion agents.

[0033] (3) Blade pretreatment: The surfaces of the parts to be infiltrated and the matching test pieces are pretreated by using a liquid sandblasting machine to remove oxide scale and other adhering substances from the surface of the parts. The corundum sand used in the liquid sandblasting machine has a particle size of 180 mesh and a working pressure of 0.3 MPa. Then, centrifugal cleaning is performed, followed by high-pressure purging.

[0034] (4) Workpiece mounting and fixing: The pretreated blades are installed on a special gas guiding fixture. The blade tenons are fixed inside the lower housing. The gas guiding pipe on the lower housing is precisely connected to the small gas guiding hole on the aluminizing frame chassis. The blade tip is sealed by the upper cover to create a dedicated gas flow channel. The reaction gas enters the center of the chassis through the central gas guiding hole of the aluminizing frame, and then flows into the lower housing through the small gas guiding hole on the chassis. That is, the reaction gas enters the blade cavity from the blade tenon and finally exhausts from the gas film hole on the blade body to form a flowing atmosphere. The internal Al generator and the special gas guiding fixture with the assembled blades are installed and fixed in sequence at the corresponding positions in the reaction chamber, and the clamping is firm and stable.

[0035] (5) Chromium-aluminum co-diffusion treatment: The external Al generator and reaction chamber are heated simultaneously. During the heating process, H2 is continuously introduced into the external Al generator and reaction chamber at a rate of 15 L / min. After the external Al generator reaches 340°C, HCl gas is introduced at a rate of 1 L / min. When the reaction chamber reaches 1000°C, Ar gas is introduced into the reaction chamber at a rate of 25 L / min, while HCl gas is introduced into the internal Cr generator for a preset duration of 120 min at a flow rate of 5 L / min. This creates a chromium layer or a chromium-rich layer on the workpiece surface under low pressure. The H2+HCl aluminizing active gas generated by the external Al generator is then introduced into the workpiece surface in the reaction chamber via the internal Al generator for 60 min, simultaneously generating a chromium-rich aluminum infiltration layer on both the inner and outer surfaces of the blade. The total deposition time is 180 min, and the pressure inside the reaction chamber is 150 mbar. After the chromium-aluminum co-infiltration deposition is completed, heating of the external Al generator and reaction chamber is stopped, the supply of HCl gas to the Al generator is stopped, and H2 gas is continuously introduced.

[0036] (6) Silicon co-infiltration treatment: After the reaction chamber cools down to 880℃, the supply of H2 to the external Al generator is stopped, and the silicon diffusion process temperature in the reaction chamber is maintained. H2 is introduced into the Si generator at a rate of 0.5 L / min, which mixes with the H2 and Ar carrier gas in the main gas pipeline in the mixing chamber to form a silicon-rich active gas. The flow rates of H2 and Ar in the silicon-rich active gas are both 15 L / min. They enter the reaction chamber with the carrier gas and form a chromium-aluminum-silicon multi-metal diffusion layer on the inner cavity and outer surface of the blade. The deposition time is 100 min, and the pressure in the reaction chamber is 150 mbar.

[0037] (7) Cooling by displacement: After the silicon infiltration process is completed, the heating of the reaction chamber and the supply of H2 to the Si generator are stopped, the Ar gas in the main pipeline is stopped, and H2 is continuously introduced at a rate of 20 L / min. When the reactor temperature drops below 500°C, the gas introduced is replaced with an inert gas instead of H2. After the temperature reaches 100°C, the reactor is removed from the furnace, and the co-infiltrated blades are cooled to room temperature.

[0038] (8) Post-processing: The blades with multi-element co-diffusion metal infiltration layers were subjected to vacuum diffusion annealing after cooling. The annealing temperature was 950℃ and the holding time was 2h, so that a complete, continuous and dense multi-element co-diffusion metal infiltration layer was formed on the inner cavity and outer surface of the blades. The multi-element co-diffusion metal infiltration layer had a mass fraction of 18% aluminum, 3% silicon, and 5% chromium.

[0039] SEM testing was performed on the multi-element co-diffusion metal infiltration layer obtained by the process method in Example 1 of this embodiment. Figure 1The metallographic structure shown shows a continuous and dense aluminum-silicon-chromium diffusion layer on the substrate surface, without local leakage or breakage. A characteristic comb-shaped interdiffusion zone is formed between the diffusion layer and the substrate. The intermetallic compound phase wedges into the substrate and grows. The diffusion layer and the substrate are metallurgically bonded, with a strong interface bond and no defects such as through cracks or large-area peeling. The diffusion layer has excellent forming quality, which is beneficial to improving the diffusion layer's resistance to peeling.

[0040] Example 2 A process for chemical vapor deposition of a multi-element co-diffusion metal diffusion layer includes the following steps: (1) Preparation of special gas guiding tooling: The blade gas guiding fixture mainly includes an aluminizing frame, a lower shell, and a top cover. The aluminizing frame chassis has a large hole in the center that connects to the gas guide holes of the internal Al generator and the internal Cr generator. Several small gas guide holes are evenly distributed on the surface of the aluminizing frame chassis. The gas guide pipe on the lower shell is connected to the small gas guide holes distributed on the aluminizing frame chassis. The shape and size of the lower shell and the top cover are designed to match the dimensions of the turbine blade tenon and blade tip structure to ensure that the fixture fits tightly with the blade and reduce the gas flow through the fit gap. After the fixture is assembled, it forms a unidirectional gas flow path consisting of the large hole in the center of the aluminizing frame chassis, the small gas guide holes in the chassis, the gas guide pipe in the lower shell, the blade inner cavity, and the blade body gas film vents, allowing the reacting gas to enter the inner cavity from the blade tenon and exit from the blade body gas film vents.

[0041] (2) Preparation for filling process infiltration agent: Bright aluminum particles are loaded into the external Al generator and the internal Al generator respectively, chromium particles are loaded into the internal Cr generator, and liquid SiCl4 is loaded into the Si generator. Based on the furnace loading amount, target diffusion layer thickness, chemical composition, diffusion layer preparation temperature and time, the loading amount of each diffusion agent and the introduction parameters of HCl, hydrogen and Ar gas are matched and determined to ensure a continuous and sufficient supply of diffusion agents.

[0042] (3) Blade pretreatment: The surfaces of the parts to be infiltrated and the matching test pieces are pretreated by using a liquid sandblasting machine to remove oxide scale and other adhering substances from the surface of the parts. The corundum sand used in the liquid sandblasting machine has a particle size of 220 mesh and a working pressure of 0.5 MPa. Then, centrifugal cleaning is performed, followed by high-pressure purging.

[0043] (4) Workpiece mounting and fixing: The pretreated blades are installed on a special gas guiding fixture. The blade tenons are fixed inside the lower housing. The gas guiding pipe on the lower housing is precisely connected to the small gas guiding hole on the aluminizing frame chassis. The blade tip is sealed by the upper cover to create a dedicated gas flow channel. The reaction gas enters the center of the chassis through the central gas guiding hole of the aluminizing frame, and then flows into the lower housing through the small gas guiding hole on the chassis. That is, the reaction gas enters the blade cavity from the blade tenon and finally exhausts from the gas film hole on the blade body to form a flowing atmosphere. The internal Al generator and the special gas guiding fixture with the assembled blades are installed and fixed in sequence at the corresponding positions in the reaction chamber, and the clamping is firm and stable.

[0044] (5) Chromium-aluminum co-diffusion treatment: The external Al generator and reaction chamber are heated simultaneously. During the heating process, H2 is continuously introduced into the external Al generator and reaction chamber at a rate of 35 L / min. After the external Al generator reaches 200°C, HCl gas is introduced at a rate of 2.5 L / min. When the reaction chamber reaches 900°C, Ar gas is introduced into the reaction chamber at a rate of 20 L / min, while HCl gas is introduced into the internal Cr generator for a preset duration of 90 min at a flow rate of 3 L / min. This creates a chromium layer or a chromium-rich layer on the workpiece surface under low pressure. The H2+HCl aluminizing active gas generated by the external Al generator is then introduced into the reaction chamber via the internal Al generator onto the workpiece surface for 50 min, simultaneously generating a chromium-rich aluminum infiltration layer on both the inner and outer surfaces of the blade. The total deposition time is 140 min, and the pressure inside the reaction chamber is 200 mbar. After the chromium-aluminum co-infiltration deposition is completed, heating of the external Al generator and reaction chamber is stopped, the supply of HCl gas to the Al generator is stopped, and H2 gas is continuously introduced.

[0045] (6) Silicon co-infiltration treatment: After the reaction chamber cools down to 900℃, the supply of H2 to the external Al generator is stopped, and the silicon diffusion process temperature in the reaction chamber is maintained. H2 is introduced into the Si generator at a rate of 0.8 L / min, which mixes with the H2 and Ar carrier gas in the main gas pipeline in the mixing chamber to form a silicon-rich active gas. The flow rates of H2 and Ar in the silicon-rich active gas are both 15 L / min. They enter the reaction chamber with the carrier gas and form a chromium-aluminum-silicon multi-metal diffusion layer on the inner cavity and outer surface of the blade. The deposition time is 50 min, and the pressure in the reaction chamber is 250 mbar.

[0046] (7) Cooling by displacement: After the silicon infiltration process is completed, the heating of the reaction chamber and the supply of H2 to the Si generator are stopped, the Ar gas is stopped from being introduced into the main pipeline, and H2 is continuously introduced at a rate of 25 L / min. When the reactor temperature drops below 500°C, the gas introduced is replaced with an inert gas instead of H2. After the temperature reaches 100°C, the reactor is removed from the furnace, and the co-infiltrated blades are cooled to room temperature.

[0047] (8) Post-processing: The blades with multi-element co-diffusion metal infiltration layers after cooling were subjected to vacuum diffusion annealing at a temperature of 1050℃ and a holding time of 2.5h, so that a complete, continuous and dense multi-element co-diffusion metal infiltration layer was formed on the inner cavity and outer surface of the blades. The multi-element co-diffusion metal infiltration layer contained in the layer was 30% by mass of aluminum, 6% by mass of silicon, and 3.6% by mass of chromium.

[0048] Example 3 A process for chemical vapor deposition of a multi-element co-diffusion metal diffusion layer includes the following steps: (1) Preparation of special gas guiding tooling: The blade gas guiding fixture mainly includes an aluminizing frame, a lower shell, and a top cover. The aluminizing frame chassis has a large hole in the center that connects to the gas guide holes of the internal Al generator and the internal Cr generator. Several small gas guide holes are evenly distributed on the surface of the aluminizing frame chassis. The gas guide pipe on the lower shell is connected to the small gas guide holes distributed on the aluminizing frame chassis. The shape and size of the lower shell and the top cover are designed to match the dimensions of the turbine blade tenon and blade tip structure to ensure that the fixture fits tightly with the blade and reduce the gas flow through the fit gap. After the fixture is assembled, it forms a unidirectional gas flow path consisting of the large hole in the center of the aluminizing frame chassis, the small gas guide holes in the chassis, the gas guide pipe in the lower shell, the blade inner cavity, and the blade body gas film vents, allowing the reacting gas to enter the inner cavity from the blade tenon and exit from the blade body gas film vents.

[0049] (2) Preparation for filling process infiltration agent: Bright aluminum particles are loaded into the external Al generator and the internal Al generator respectively, chromium particles are loaded into the internal Cr generator, and liquid SiCl4 is loaded into the Si generator. Based on the furnace loading amount, target diffusion layer thickness, chemical composition, diffusion layer preparation temperature and time, the loading amount of each diffusion agent and the introduction parameters of HCl, hydrogen and Ar gas are matched and determined to ensure a continuous and sufficient supply of diffusion agents.

[0050] (3) Blade pretreatment: The surfaces of the parts to be infiltrated and the matching test pieces are pretreated by using a liquid sandblasting machine to remove oxide scale and other adhering substances from the surface of the parts. The corundum sand used in the liquid sandblasting machine has a particle size of 120 mesh and a working pressure of 0.2 MPa. Then, centrifugal cleaning is performed, followed by high-pressure purging.

[0051] (4) Workpiece mounting and fixing: The pretreated blades are installed on a special gas guiding fixture. The blade tenons are fixed inside the lower housing. The gas guiding pipe on the lower housing is precisely connected to the small gas guiding hole on the aluminizing frame chassis. The blade tip is sealed by the upper cover to create a dedicated gas flow channel. The reaction gas enters the center of the chassis through the central gas guiding hole of the aluminizing frame, and then flows into the lower housing through the small gas guiding hole on the chassis. That is, the reaction gas enters the blade cavity from the blade tenon and finally exhausts from the gas film hole on the blade body to form a flowing atmosphere. The internal Al generator and the special gas guiding fixture with the assembled blades are installed and fixed in sequence at the corresponding positions in the reaction chamber, and the clamping is firm and stable.

[0052] (5) Chromium-aluminum co-diffusion treatment: The external Al generator and reaction chamber are heated simultaneously. During the heating process, H2 is continuously introduced into the external Al generator and reaction chamber at a rate of 25 L / min. After the external Al generator reaches 400°C, HCl gas is introduced at a rate of 1.7 L / min. When the reaction chamber reaches 1100°C, Ar gas is introduced into the reaction chamber at a rate of 35 L / min, while HCl gas is introduced into the internal Cr generator for a preset duration of 60 min at a flow rate of 2 L / min. This creates a chromium layer or a chromium-rich layer on the workpiece surface under low pressure. The H2+HCl aluminizing active gas generated by the external Al generator is then introduced into the workpiece surface in the reaction chamber via the internal Al generator for 40 min, simultaneously generating a chromium-rich aluminum infiltration layer on both the inner and outer surfaces of the blade. The total deposition time is 100 min, and the pressure inside the reaction chamber is 250 mbar. After the chromium-aluminum co-infiltration deposition is completed, the heating of the external Al generator and reaction chamber is stopped, the supply of HCl gas to the Al generator is stopped, and H2 gas is continuously introduced.

[0053] (6) Silicon co-infiltration treatment: After the reaction chamber cools down to 950℃, the supply of H2 to the external Al generator is stopped, and the silicon diffusion process temperature in the reaction chamber is maintained. H2 is introduced into the Si generator at a rate of 0.6 L / min, which mixes with the H2 and Ar carrier gas in the main gas pipeline in the mixing chamber to form a silicon-rich active gas. The flow rates of H2 and Ar in the silicon-rich active gas are both 15 L / min. They enter the reaction chamber with the carrier gas and form a chromium-aluminum-silicon multi-metal diffusion layer on the inner cavity and outer surface of the blade. The deposition time is 80 min, and the pressure in the reaction chamber is 200 mbar.

[0054] (7) Cooling by displacement: After the silicon infiltration process is completed, the heating of the reaction chamber and the supply of H2 to the Si generator are stopped, the Ar gas in the main pipeline is stopped, and H2 is continuously introduced at a rate of 30 L / min. When the reactor temperature drops below 500°C, the gas introduced is replaced with an inert gas instead of H2. After the temperature reaches 100°C, the reactor is removed from the furnace, and the co-infiltrated blades are cooled to room temperature.

[0055] (8) Post-processing: The blades with multi-element co-diffusion metal infiltration layers were subjected to vacuum diffusion annealing at a temperature of 1020℃ and a holding time of 3h to form a complete, continuous, and dense multi-element co-diffusion metal infiltration layer on the inner cavity and outer surface of the blades. The layer contained 26% aluminum, 4.2% silicon, and 3% chromium.

Claims

1. A process for chemical vapor deposition of a multi-element co-diffusion metal layer, characterized in that, Includes the following steps: (1) Preparation of special gas guiding tooling: The blade gas guide fixture mainly includes an aluminizing frame, a lower shell, and a upper cover. The aluminizing frame chassis has a large hole in the center that connects to the air guide holes of the internal Al generator and the internal Cr generator. Several small air guide holes are evenly distributed on the surface of the aluminizing frame chassis. The shape and size of the lower shell and the upper cover are designed to match the dimensions of the turbine blade tenon and blade tip structure. (2) Preparation for filling process infiltration agent: Bright aluminum particles were loaded into the external Al generator and the internal Al generator respectively, chromium particles were loaded into the internal Cr generator, and liquid SiCl4 was loaded into the Si generator. (3) Blade pretreatment: The surfaces of the parts to be infiltrated and the matching test pieces are pretreated by using a liquid sandblasting machine to remove oxide scale and other adhering substances from the surface of the parts; then they are cleaned and blew. (4) Workpiece mounting and fixing: The pre-treated blades are installed on a special gas guiding fixture. The blade tenons are fixed inside the lower shell. The gas guiding pipe on the lower shell is precisely connected to the small gas guiding hole of the aluminized frame chassis. The blade tip is sealed by the upper cover to build a dedicated gas flow channel. The internal Al generator and the special gas guiding fixture with assembled blades are installed and fixed in the corresponding positions in the reaction chamber in sequence, and the clamping is firm and stable. (5) Chromium-aluminum co-diffusion treatment: The external Al generator and reaction chamber are heated simultaneously. During the heating process, H2 is continuously introduced into the external Al generator and reaction chamber. After the external Al generator reaches the preset temperature, HCl gas is introduced. After the reaction chamber is heated to the chromium-aluminum co-diffusion process temperature, Ar gas is introduced into the reaction chamber, and HCl gas is introduced into the internal Cr generator for a preset duration. Under low pressure, a chromium layer or a chromium-rich layer is formed on the surface of the workpiece. Then, the H2+HCl aluminizing active gas generated by the external Al generator is introduced into the surface of the workpiece in the reaction chamber through the internal Al generator, and a chromium-rich aluminum diffusion layer is generated simultaneously in the inner cavity and outer surface of the blade. After the chromium-aluminum co-diffusion deposition is completed, the heating of the external Al generator and reaction chamber is stopped, the introduction of HCl gas into the Al generator is stopped, and H2 gas is continuously introduced. (6) Silicon co-infiltration treatment: After the reaction chamber cools down to the silicon diffusion process temperature, stop supplying H2 to the external Al generator, maintain the silicon diffusion process temperature in the reaction chamber, and supply H2 to the Si generator so that it mixes with the H2 and Ar carrier gas in the main gas pipeline in the mixing chamber to form a silicon-rich active gas. The active gas enters the reaction chamber with the carrier gas and forms a chromium-aluminum-silicon multi-metal diffusion layer in the inner cavity and outer surface of the blade. (7) Cooling by displacement: After the silicon infiltration process is completed, stop heating the reaction chamber and supplying H2 to the Si generator, stop the Ar gas inlet in the main pipeline and continue to supply H2; when the reactor temperature drops below 500℃, replace the gas inlet with H2 and inert gas, and remove the reactor when the temperature reaches 100℃. The co-infiltrated blades are then cooled to room temperature. (8) Post-processing: Vacuum diffusion annealing is performed on the blades with multi-element co-diffusion metal infiltration layers after cooling, so that a complete, continuous and dense multi-element co-diffusion metal infiltration layer is formed on the inner cavity and outer surface of the blades.

2. The process for chemical vapor deposition of a multi-element co-diffusion metal layer according to claim 1, characterized in that, In step (1), the gas guide pipe on the lower shell is connected to the small gas guide holes distributed on the aluminized frame chassis. After the tooling is assembled, a one-way gas flow path is formed by the large central hole of the aluminized frame chassis, the small gas guide holes of the chassis, the gas guide pipe of the lower shell, the inner cavity of the blade, and the gas film hole of the blade body, so that the reaction gas enters the inner cavity from the blade tenon and exits from the gas film hole of the blade body.

3. The process for chemical vapor deposition of a multi-element co-diffusion metal layer according to claim 1, characterized in that, In step (2), based on the furnace loading amount, target diffusion layer thickness, chemical composition, diffusion layer preparation temperature and time, the loading amount of each diffusion agent and the parameters for introducing HCl, hydrogen and Ar gas are matched and determined to ensure a continuous and sufficient supply of diffusion agents.

4. The process for chemical vapor deposition of a multi-element co-diffusion metal layer according to claim 1, characterized in that, In step (3), the corundum sand used in the liquid sand blowing machine has a particle size of 120 mesh to 220 mesh and a working pressure of 0.2 MPa to 0.5 MPa; the cleaning method is centrifugal cleaning and the blowing method is high-pressure blowing.

5. The process for chemical vapor deposition of a multi-element co-diffusion metal layer according to claim 1, characterized in that, In step (4), the reaction gas in the dedicated gas flow channel enters the center of the chassis through the central air guide hole of the aluminized frame, and then flows into the lower shell through the small air guide hole on the chassis. That is, the reaction gas enters the inner cavity of the blade from the blade tenon and finally exhausts from the air film hole of the blade body to form a flowable atmosphere.

6. The process for chemical vapor deposition of a multi-element co-diffusion metal layer according to claim 1, characterized in that, In step (5), the preset temperature is 200℃~400℃, the chromium-aluminum co-diffusion process temperature is heated to 900℃~1100℃, H2 and HCl gases are introduced into the external Al generator, the H2 flow rate is 15L / min~35L / min, the HCl flow rate is 1L / min~2.5L / min; the Ar gas flow rate is 10L / min~30L / min introduced into the reaction chamber; the preset duration of HCl gas introduced into the internal Cr generator is 60min~120min, and the HCl gas flow rate is 2L / min~5L / min.

7. The process for chemical vapor deposition of a multi-element co-diffusion metal diffusion layer according to claim 1, characterized in that, In step (5), the total deposition time for the chromium-aluminum co-diffusion treatment is 100 min to 180 min, and the pressure in the reaction chamber is 150 mbar to 250 mbar.

8. The process for chemical vapor deposition of a multi-element co-diffusion metal layer according to claim 1, characterized in that, In step (6), the silicon diffusion process temperature is 880℃~950℃; the flow rate of H2 introduced into the Si generator is 0.5L / min~0.8L / min; the flow rates of H2 and Ar in the silicon-rich active gas are both 15L / min; The deposition time for silicon co-diffusion treatment is 50 min to 100 min, and the pressure in the reaction chamber is 150 mbar to 250 mbar.

9. The process for chemical vapor deposition of a multi-element co-diffusion metal layer according to claim 1, characterized in that, In step (7), the flow rate of H2 continuously introduced is 20L / min to 30L / min.

10. The process for chemical vapor deposition of a multi-element co-diffusion metal layer according to claim 1, characterized in that, In step (8), the annealing temperature of the vacuum diffusion annealing treatment is 950℃~1050℃, and the holding time is 2h~3h; In the multi-element co-diffusion metal infiltration layer, the mass fraction of aluminum can be controlled within the range of 18% to 30%, the mass fraction of silicon can be controlled within the range of 3% to 6%, and the mass fraction of chromium can be controlled within the range of 3% to 5%.

Images