A method for eliminating interdiffusion between carbon steel can and TiAl alloy by using chemical oxidation process

Abstract

The application discloses a method for eliminating mutual diffusion between a carbon steel sheath and a TiAl alloy by using a chemical oxidation process, and the method comprises the following steps: smearing an oxidation solution on a contact position of the carbon steel sheath and a TiAl alloy component, and generating a dense Fe3O4 oxidation film on the surface of the carbon steel sheath, so as to hinder mutual diffusion between the carbon steel sheath and the TiAl alloy in the process of hot isostatic pressing, and reduce the difficulty of removing the carbon steel sheath, and the hot isostatic pressing component can be subjected to subsequent heat treatment after a small amount of polishing, so that a new idea is provided for saving time and labor cost in a production process, and the method is very beneficial to actual operation.

Description

Technical Field

[0001] This invention belongs to the field of materials science and engineering application technology, and specifically relates to a method for eliminating interdiffusion between carbon steel cladding and TiAl alloy using a chemical oxidation process. Background Technology

[0002] Carbon steel is a commonly used cladding material for titanium alloy powder coatings due to its low price, good weldability, and strong deformation capacity. However, interdiffusion occurs between the carbon steel cladding and the TiAl alloy, resulting in a diffusion layer containing Fe on the surface of the TiAl alloy hot isostatic pressed parts, forming Ti... x Fe y Fe x Al y Intermetallic compounds such as Fe are formed. During subsequent heat treatment, Fe is oxidized to produce Fe2O3. The porous structure of Fe2O3 leads to the oxidation of the internal TiAl alloy, ultimately rendering the entire workpiece unusable. In actual production, grinding is generally used to remove the diffusion layer on the surface of TiAl alloy components. However, powder metallurgy TiAl-based alloy compacts obtained by hot isostatic pressing at 1200~1300℃ exhibit a bimodal structure, high room temperature hardness, and the grinding process is time-consuming and labor-intensive, increasing the processing cycle and labor costs of hot isostatic pressing powder metallurgy technology in the preparation of TiAl-based alloys. Therefore, it is essential to use new methods to eliminate the negative impact of the diffusion layer on powder metallurgy TiAl alloys. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for eliminating the interdiffusion between carbon steel cladding and TiAl alloy using a chemical oxidation process.

[0004] To solve the technical problem, the technical solution of the present invention is: a method for eliminating interdiffusion between carbon steel cladding and TiAl alloy using a chemical oxidation process, comprising the following steps: Step 1: Prepare TiAl alloy powder; Step 2: Prepare the various components of the carbon steel sheath according to the drawings; Step 3: Place each component of the carbon steel sheath into the degreasing agent solution in the degreasing tank for degreasing treatment; Step 4: Perform shot blasting to remove rust from all components of the carbon steel sheath; Step 5: Prepare the oxidation solution; Step 6: Apply an oxide solution to the contact points between the carbon steel sheathed components and the TiAl alloy components to react and generate a dense oxide film. Step 7: Weld the various components of the carbon steel sheath together to form the carbon steel sheath, and then weld the vacuum connector to the top of the carbon steel sheath as the powder inlet. Step 8: Leak test the welded carbon steel sheath; Step 9: After the leak test is passed, place the carbon steel sheath on the vibration platform and add TiAl alloy powder while vibrating until it is full; Step 10: Connect the carbon steel sheath filled with powder to the vacuum pump using the exhaust pipe for degassing. After the degassing is completed, seal the carbon steel sheath to obtain a sealed carbon steel sheath containing TiAl alloy powder. Step 11: After the sealing carbon steel sleeve is completed, an airtightness test is performed. After the airtightness test is passed, hot isostatic pressing densification treatment is performed. After the hot isostatic pressing densification treatment is completed, the carbon steel sleeve is removed to obtain a TiAl alloy component without an Fe diffusion layer.

[0005] Preferably, the TiAl alloy powder in step 1 is a pure TiAl alloy powder with a particle size range of 53~106μm obtained by multi-stage sieving, and inclusions are removed by electrostatic separation.

[0006] Preferably, the components of the carbon steel sheath in step 2 include a sheath base, a sheath body, and a sheath cover. When preparing the carbon steel sheath, the dimensions of the carbon steel sheath are designed according to the dimensional requirements of the TiAl alloy components, while allowing for machining allowances for the TiAl alloy components.

[0007] Preferably, step 3 specifically involves: placing each component of the carbon steel sheath in an oil removal tank at 80-90°C for oil removal treatment. The oil removal tank is filled with an oil removal agent solution, and the tank is heated at high temperature for 20-30 minutes. After the oil removal is completed, the surface of each component of the carbon steel sheath is washed with running water to remove the oil removal agent solution.

[0008] Preferably, the degreasing agent solution includes, but is not limited to, the following: The first type: NaOH, Na2CO3 and water, with a weight ratio of NaOH, Na2CO3 and water of 5~6:7~8:100; The second type: NaOH, Na2CO3, Na3PO4, NaSiO3 and water, with a weight ratio of 130:50:50:4:1000. The third type consists of Na2CO3, NaOH, trisodium pyrophosphate, NaSiO3, Na3PO4, and water, with a weight ratio of 2:1:1:2:10:200.

[0009] Preferably, the oxidation solution in step 5 includes, but is not limited to, the following: The first method involves an oxidation solution consisting of 600 g / L NaOH and 200 g / L NaNO2, with a treatment temperature of 25°C and a treatment time of 25-30 min. The second method: The oxidation solution consists of 600 g / L NaOH, 55 g / L NaNO2, and 20 g / L Na3PO4. The treatment temperature is 130℃ and the treatment time is 60~90 min. The third method: The oxidation solution consists of 600 g / L NaOH, 200 g / L NaNO2, and 25 g / L K2Cr2O7. The treatment temperature is 130℃ and the treatment time is 15 min. Step 6 specifically involves applying an oxidation solution to the contact points between each component of the carbon steel sheath and the TiAl alloy component, causing an oxidation reaction to generate a dense Fe3O4 oxide film. After the oxidation reaction is complete, each component of the carbon steel sheath should be cleaned and then dried.

[0010] Preferably, step 7 specifically involves: welding the bottom of the sheath, the body of the sheath, and the cover of the sheath together, and then welding the KF25 vacuum connector to the top of the cover of the sheath as a powder inlet, using argon arc welding during welding; in step 8, the welded carbon steel sheath is inspected for leaks, and any leaking carbon steel sheaths need to be re-welded.

[0011] Preferably, step 9 specifically involves: placing the carbon steel sheath on a vibration platform with a vibration frequency of 20-40Hz, adding TiAl alloy powder while vibrating, and indicating that the TiAl alloy powder in the carbon steel sheath is full when it stops falling after vibrating for 20-30 minutes.

[0012] Preferably, the specific method for degassing the carbon steel sheath in step 10 is as follows: Step 10-1: Weld an exhaust pipe to the vacuum joint of the carbon steel sheath, connect the carbon steel sheath to the degassing machine through the exhaust pipe, and place it into the heating furnace; Step 10-2: Degas using a mechanical pump at room temperature until the internal pressure of the carbon steel sheath drops below 10 Pa; Step 10-3: Degas using a diffusion pump at room temperature until the internal pressure of the carbon steel sheath drops to 10. -2 ~10 -3 Pa; Step 10-4: Raise the temperature to 150~200℃ and hold for 1~2 hours; raise the temperature to 250~300℃ and hold for 2~3 hours; raise the temperature to 400~500℃ and hold for 4~5 hours. Step 10-5: Seal and weld the exhaust pipe of the carbon steel sheath, and remove it from the heating furnace to obtain a sealed carbon steel sheath.

[0013] Preferably, the airtightness test method in step 11 is as follows: the sealed carbon steel sheath after sealing is placed in hot water at 70~80℃. If no bubbles emerge from the surface of the sheath within 10~15 minutes, it indicates that the airtightness of the sealed carbon steel sheath is qualified. The temperature of the hot isostatic pressing densification treatment is 1200~1300℃, the time is 3~6 hours, and the pressure is 100~150MPa.

[0014] Compared with the prior art, the advantages of the present invention are as follows: (1) This invention discloses a method for eliminating the interdiffusion between carbon steel cladding and TiAl alloy using a chemical oxidation process. By applying an oxidation solution to the contact position between the carbon steel cladding and the TiAl alloy component, a dense oxide film is generated on the surface of the carbon steel cladding, which hinders the interdiffusion between the carbon steel cladding and the TiAl alloy during hot isostatic pressing. This method also reduces the difficulty of removing the carbon steel cladding. Furthermore, the hot isostatic pressed component can be subjected to subsequent heat treatment after only a small amount of grinding. This provides a new approach to saving time and labor costs in the production process and is very beneficial for practical operation. (2) The present invention improves the cleanliness of the carbon steel sheath surface by using degreasing and derusting methods, avoids the obstruction of chemical oxidation treatment by impurities, strengthens the contact between the oxidation solution and the carbon steel sheath, and avoids the generation of oxide film leaks. (3) The present invention welds the carbon steel sheath after the chemical oxidation process, which can avoid the poor contact between the weld seam and the oxidation solution affecting the coverage of the oxide film, and can also prevent the oxidation solution from reacting with the weld and affecting the weld quality. (4) The degassing treatment of the carbon steel sheath of the present invention adopts a staged degassing method. A mechanical pump is used at low vacuum and a diffusion pump is used at high vacuum. At the same time, high temperature heating is used to promote the escape of the gas adsorbed by the powder, which is conducive to the complete removal of gas. The hot isostatic pressing of the present invention uses higher temperature and pressure, which can obtain TiAl alloy billet with higher density. (5) The method of the present invention is transferable. For alloys similar to TiAl alloys that have interdiffusion with carbon steel cladding, the method of the present invention can be used to use the oxide film to hinder diffusion and achieve the purpose of eliminating the diffusion layer. Therefore, the present invention has a wide application prospect in the field of powder alloys. Attached Figure Description

[0015] Figure 1 A schematic flowchart of a method for eliminating interdiffusion between carbon steel cladding and TiAl alloy using chemical oxidation process according to the present invention; Figure 2 A schematic diagram of the structure of the carbon steel sheath of the present invention.

[0016] Explanation of reference numerals in the attached figures: 1. Sleeve bottom, 2. Sleeve body, 3. Sleeve cap. Detailed Implementation

[0017] The specific implementation of the present invention is described below with reference to embodiments: It should be noted that the structures, proportions, sizes, etc. shown in this specification are only used to complement the content disclosed in the specification for those skilled in the art to understand and read, and are not intended to limit the conditions under which the present invention can be implemented. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0018] Example 1 This invention discloses a method for eliminating interdiffusion between carbon steel cladding and TiAl alloy using a chemical oxidation process, comprising the following steps: Step 1: Prepare TiAl alloy powder; Step 2: Prepare the various components of the carbon steel sheath according to the drawings; Step 3: Place each component of the carbon steel sheath into the degreasing agent solution in the degreasing tank for degreasing treatment; Step 4: Perform shot blasting to remove rust from all components of the carbon steel sheath; Step 5: Prepare the oxidation solution; Step 6: Apply an oxide solution to the contact points between the carbon steel sheathed components and the TiAl alloy components to react and generate a dense oxide film. Step 7: Weld the various components of the carbon steel sheath together to form the carbon steel sheath, and then weld the vacuum connector to the top of the carbon steel sheath as the powder inlet. Step 8: Leak test the welded carbon steel sheath; Step 9: After the leak test is passed, place the carbon steel sheath on the vibration platform and add TiAl alloy powder while vibrating until it is full; Step 10: Connect the carbon steel sheath filled with powder to the vacuum pump using the exhaust pipe for degassing. After the degassing is completed, seal the carbon steel sheath to obtain a sealed carbon steel sheath containing TiAl alloy powder. Step 11: After the sealing carbon steel sleeve is completed, an airtightness test is performed. After the airtightness test is passed, hot isostatic pressing densification treatment is performed. After the hot isostatic pressing densification treatment is completed, the carbon steel sleeve is removed to obtain a TiAl alloy component without an Fe diffusion layer.

[0019] Example 2 Preferably, the TiAl alloy powder in step 1 is pure TiAl alloy powder with a particle size range of 53~106μm obtained through multi-stage sieving.

[0020] like Figure 2As shown, preferably, the components of the carbon steel sheath in step 2 include a sheath base 1, a sheath body 2, and a sheath cover 3. When preparing the carbon steel sheath, the dimensions of the carbon steel sheath are designed according to the dimensional requirements of the TiAl alloy components, while leaving a machining allowance for the TiAl alloy components.

[0021] Example 3 Preferably, step 3 specifically involves: placing each component of the carbon steel sheath in an oil removal tank at 80-90°C for oil removal treatment. The oil removal tank is filled with an oil removal agent solution, and the tank is heated at high temperature for 20-30 minutes. After the oil removal is completed, the surface of each component of the carbon steel sheath is washed with running water to remove the oil removal agent solution.

[0022] Preferably, the degreasing agent solution includes, but is not limited to, the following: The first type: NaOH, Na2CO3 and water, with a weight ratio of NaOH, Na2CO3 and water of 5~6:7~8:100; The second type: NaOH, Na2CO3, Na3PO4, NaSiO3 and water, with a weight ratio of 130:50:50:4:1000. The third type consists of Na2CO3, NaOH, trisodium pyrophosphate, NaSiO3, Na3PO4, and water, with a weight ratio of 2:1:1:2:10:200.

[0023] The degreasing agent solution is an aqueous solution of NaOH and Na2CO3, and its formula is: 50~60g NaOH, 70~80g Na2CO3, and 1000mL water.

[0024] Preferably, the oxidation solution in step 5 includes, but is not limited to, the following: The first method involves an oxidation solution consisting of 600 g / L NaOH and 200 g / L NaNO2, with a treatment temperature of 25°C and a treatment time of 25-30 min. The second method: The oxidation solution consists of 600 g / L NaOH, 55 g / L NaNO2, and 20 g / L Na3PO4. The treatment temperature is 130℃ and the treatment time is 60~90 min. The third method: The oxidation solution consists of 600 g / L NaOH, 200 g / L NaNO2, and 25 g / L K2Cr2O7. The treatment temperature is 130℃ and the treatment time is 15 min. Step 6 specifically involves applying an oxidation solution to the contact points between each component of the carbon steel sheath and the TiAl alloy component, causing an oxidation reaction to generate a dense Fe3O4 oxide film. After the oxidation reaction is complete, each component of the carbon steel sheath should be cleaned and then dried.

[0025] The oxidation solution can be any solvent that can chemically oxidize carbon steel to produce a dense Fe3O4 oxide film.

[0026] Example 4 Preferably, step 7 specifically involves: welding the bottom of the sheath, the body of the sheath, and the cover of the sheath together, and then welding the KF25 vacuum connector to the top of the cover of the sheath as a powder inlet, using argon arc welding during welding; in step 8, the welded carbon steel sheath is inspected for leaks, and any leaking carbon steel sheaths need to be re-welded.

[0027] Preferably, step 9 specifically involves: placing the carbon steel sheath on a vibration platform with a vibration frequency of 20-40Hz, adding TiAl alloy powder while vibrating, and indicating that the TiAl alloy powder in the carbon steel sheath is full when it stops falling after vibrating for 20-30 minutes.

[0028] Example 5 Preferably, the specific method for degassing the carbon steel sheath in step 10 is as follows: Step 10-1: Weld an exhaust pipe to the vacuum joint of the carbon steel sheath, connect the carbon steel sheath to the degassing machine through the exhaust pipe, and place it into the heating furnace; Step 10-2: Degas using a mechanical pump at room temperature until the internal pressure of the carbon steel sheath drops below 10 Pa; Step 10-3: Degas using a diffusion pump at room temperature until the internal pressure of the carbon steel sheath drops to 10. -2 ~10 -3 Pa; Step 10-4: Raise the temperature to 150~200℃ and hold for 1~2 hours; raise the temperature to 250~300℃ and hold for 2~3 hours; raise the temperature to 400~500℃ and hold for 4~5 hours. Step 10-5: Seal and weld the exhaust pipe of the carbon steel sheath, and remove it from the heating furnace to obtain a sealed carbon steel sheath.

[0029] Preferably, the airtightness test method in step 11 is as follows: the sealed carbon steel sheath after sealing is placed in hot water at 70~80℃. If no bubbles emerge from the surface of the sheath within 10~15 minutes, it indicates that the airtightness of the sealed carbon steel sheath is qualified. The temperature of the hot isostatic pressing densification treatment is 1200~1300℃, the time is 3~6 hours, and the pressure is 100~150MPa.

[0030] Example 6 like Figure 1 As shown, the present invention mainly includes the following steps: Prepare TiAl alloy powder and remove inclusions using electrostatic separation; Prepare a casing structure, apply an oxidation solution to the surface where the casing contacts the material to generate a dense oxide film; Fill the welded casing with powder; After the powder is filled, degas and seal the packaging. The cladding is subjected to hot isostatic pressing. Remove the cladding structure to obtain a TiAl alloy component without a diffusion layer.

[0031] The specific operation of the above method in this embodiment is as follows: (1) Prepare TiAl alloy powder, and obtain pure TiAl alloy powder with a particle size range of 53~106μm through multi-stage sieving, and remove inclusions by electrostatic separation. (2) By analyzing the deformation of carbon steel sheath in hot isostatic pressing, and combining simulation results with actual experience, the carbon steel sheath is designed. The space reserved for hot isostatic pressing deformation and the allowance for machining after forming are specially designed. At the beginning of deformation, the soft sheath deforms first to achieve powder densification. In the later stage of deformation, the sheath and TiAl alloy deform together. (3) Place the carbon steel sheath in an oil removal tank at 80~90℃ for oil removal treatment and heat it at high temperature for 20~30 minutes. The oil removal agent is an aqueous solution of NaOH and Na2CO3. The formula is 50~60g NaOH, 70~80g Na2CO3 and 1000mL water. After the oil removal is completed, wash the oil removal agent solution with running water. (4) Perform shot blasting to remove rust from the carbon steel sheath; (5) Prepare carbon steel oxidation solution. In this example, alkaline sodium nitrite solution is used, which can undergo oxidation reaction at room temperature. The composition of the solution is: NaOH 600~700g / L, NaNO2 200~250g / L.

[0032] (6) Apply an oxidation solution to the contact position between the carbon steel sheath and the TiAl alloy component to generate a dense Fe3O4 oxide film; the composition of the oxidation solution is alkaline sodium nitrite solution, the oxidation reaction time is 25~30min, and the thickness of the oxide film is 0.5~3μm. (7) Prepare the carbon steel sheath bottom, sheath body and sheath cover according to the drawings, prepare KF25 vacuum connector, and assemble the parts together using argon arc welding. (8) Check the carbon steel sheath for leaks. If the sheath leaks, it needs to be re-welded. (9) Place the carbon steel sheath on the vibration platform and vibrate at a frequency of 20~40Hz. Add TiAl alloy powder while vibrating. When the TiAl alloy powder in the carbon steel sheath stops falling after vibrating for 20~30 minutes, it means that the powder is full. (10) Degas the carbon steel sheath after it has been filled with powder. The specific method for degassing is as follows: S1) Weld an exhaust pipe to the vacuum joint of the shroud, connect the shroud to the degasser through the exhaust pipe, and place it into the heating furnace; S2) Use a mechanical pump to degas at room temperature until the pressure inside the casing drops below 10 Pa; S3) Degas using a diffusion pump at room temperature until the pressure inside the cladding drops to 10. -2 ~10 -3 Pa; S4) Heat to 150~200℃ and hold for 1~2 hours; heat to 250~300℃ and hold for 2~3 hours; heat to 400~500℃ and hold for 4~5 hours. S5) Once the vacuum level inside the casing meets the requirements, seal the exhaust pipe of the casing and remove it to obtain a sealed casing containing powder. Place the sealed casing after sealing into hot water at 70~80℃. If no bubbles emerge from the surface of the casing within 10~15 minutes, it indicates that the airtightness of the casing is qualified and subsequent hot isostatic pressing densification treatment can be carried out.

[0033] (11) After the sealing carbon steel sleeve is completed, the air tightness is checked. After the air tightness is qualified, hot isostatic pressing densification treatment is carried out. The temperature of hot isostatic pressing treatment of the sleeve is 1200~1300℃, the time of hot isostatic pressing treatment is 3~6h, and the pressure of hot isostatic pressing treatment is 100~150MPa, so as to obtain TiAl alloy component without Fe diffusion layer.

[0034] Samples were taken from the pressed blanks of the above-mentioned TiAl alloy components, and the thickness of the diffusion layer between the carbon steel cladding and the TiAl alloy was observed under a scanning electron microscope. The results are shown in the table below.

[0035]

[0036] The results show that the thickness of the diffusion layer of the pressed sample using the chemical oxidation process of the present invention is significantly reduced by 80% to 90%, indicating that the oxide film generated by the oxidation reaction can eliminate the interdiffusion between the carbon steel cladding and the TiAl alloy.

[0037] In the prior art, TiAl alloy billets after removing the cladding need to be repeatedly polished. At the same time, the diffusion layer is judged by observing whether rust is present when immersed in water or by observing corrosion products when corroded by strong acid. However, the pressed billet after using the chemical oxidation process of this invention only needs to be polished to remove the diffusion layer on its surface. This can save 80% of the labor and time costs in the polishing process.

[0038] The foregoing has provided a detailed description of a method for eliminating interdiffusion between TiAl alloy hot isostatic pressed parts and carbon steel sheaths using a chemical oxidation process, as provided in the embodiments of the present invention. The descriptions of the embodiments above are merely for the purpose of helping to understand the method and its core ideas; furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

[0039] The working principle of this invention is as follows: like Figure 1 As shown, this invention discloses a method for eliminating interdiffusion between TiAl alloy hot isostatic pressed parts and carbon steel cladding using a chemical oxidation process. This method involves applying an oxide solution to the contact area between the carbon steel cladding and TiAl alloy powder, generating a dense oxide film through chemical oxidation. This film prevents direct contact between the carbon steel cladding and the TiAl alloy, thus eliminating the diffusion of Ti Al in the diffusion layer. x Fe y Fe x Al y The formation of intermetallic compounds reduces the manpower and time costs required for subsequent removal of the diffusion layer, and avoids the scrapping of TiAl alloy components during heat treatment due to the oxidation of Fe in the diffusion layer.

[0040] This invention discloses a method for eliminating interdiffusion between carbon steel sheathing and TiAl alloy using a chemical oxidation process. By applying an oxide solution to the contact area between the carbon steel sheathing and the TiAl alloy component, a dense oxide film is formed on the surface of the carbon steel sheathing, which hinders the interdiffusion between the carbon steel sheathing and the TiAl alloy during hot isostatic pressing. This method also reduces the difficulty of removing the carbon steel sheathing, and the hot isostatic pressed component can be subjected to subsequent heat treatment after only a small amount of grinding. This provides a new approach to saving time and labor costs in the production process and is highly beneficial for practical operation.

[0041] This invention improves the cleanliness of the carbon steel sheath surface by using degreasing and rust removal methods, avoids impurities from hindering the chemical oxidation process, strengthens the contact between the oxidation solution and the carbon steel sheath, and prevents the formation of oxide film leaks.

[0042] This invention involves welding a carbon steel sheath after the chemical oxidation process. This not only avoids poor contact between the weld seam and the oxidation solution, which would affect the coverage of the oxide film, but also prevents the oxidation solution from reacting with the weld seam and affecting the weld quality.

[0043] The degassing treatment of the carbon steel sheath of this invention adopts a staged degassing method, using a mechanical pump at low vacuum and a diffusion pump at high vacuum. At the same time, high temperature heating is used to promote the escape of gas adsorbed by the powder, which is conducive to the complete removal of gas. The hot isostatic pressing of this invention uses higher temperature and pressure, which can obtain TiAl alloy billets with higher density.

[0044] The method of this invention is transferable; it can be used for alloys similar to TiAl alloys that exhibit interdiffusion with carbon steel sheathing. By utilizing the oxide film to hinder diffusion, the diffusion layer can be eliminated. Therefore, this invention has broad application prospects in the field of powder alloys.

[0045] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

[0046] Many other changes and modifications can be made without departing from the concept and scope of this invention. It should be understood that this invention is not limited to the specific embodiments, and the scope of this invention is defined by the appended claims.

Claims

1. A method for eliminating interdiffusion between carbon steel cladding and TiAl alloy using a chemical oxidation process, characterized in that, Includes the following steps: Step 1: Prepare TiAl alloy powder; Step 2: Prepare the various components of the carbon steel sheath according to the drawings; Step 3: Place each component of the carbon steel sheath into the degreasing agent solution in the degreasing tank for degreasing treatment; Step 4: Perform shot blasting to remove rust from all components of the carbon steel sheath; Step 5: Prepare the oxidation solution; The oxidation solution in step 5 includes the following types: The first method involves an oxidation solution consisting of 600 g / L NaOH and 200 g / L NaNO2, with a treatment temperature of 25°C and a treatment time of 25-30 min. The second method: The oxidation solution consists of 600 g / L NaOH, 55 g / L NaNO2, and 20 g / L Na3PO4. The treatment temperature is 130℃ and the treatment time is 60~90 min. The third method: The oxidation solution consists of 600 g / L NaOH, 200 g / L NaNO2, and 25 g / L K2Cr2O7. The treatment temperature is 130℃ and the treatment time is 15 min. Step 6: Apply an oxide solution to the contact points between the carbon steel sheathed components and the TiAl alloy components to react and generate a dense oxide film. An oxidation solution is applied to the contact points between the carbon steel sheath and the TiAl alloy components to induce an oxidation reaction, forming a dense Fe3O4 oxide film. After the oxidation reaction is complete, the carbon steel sheath components are cleaned and then air-dried. Step 7: Weld the various components of the carbon steel sheath together to form the carbon steel sheath, and then weld the vacuum connector to the top of the carbon steel sheath as the powder inlet. Step 8: Leak test the welded carbon steel sheath; Step 9: After the leak test is passed, place the carbon steel sheath on the vibration platform and add TiAl alloy powder while vibrating until it is full; Step 10: Connect the carbon steel sheath filled with powder to the vacuum pump using the exhaust pipe for degassing. After the degassing is completed, seal the carbon steel sheath to obtain a sealed carbon steel sheath containing TiAl alloy powder. Step 11: After the sealing carbon steel sleeve is completed, an airtightness test is performed. After the airtightness test is passed, hot isostatic pressing densification treatment is performed. After the hot isostatic pressing densification treatment is completed, the carbon steel sleeve is removed to obtain a TiAl alloy component without an Fe diffusion layer.

2. The method for eliminating interdiffusion between carbon steel cladding and TiAl alloy using a chemical oxidation process according to claim 1, characterized in that, In step 1, the TiAl alloy powder is a pure TiAl alloy powder with a particle size range of 53~106μm obtained by multi-stage sieving, and inclusions are removed by electrostatic separation.

3. The method for eliminating interdiffusion between carbon steel cladding and TiAl alloy using a chemical oxidation process according to claim 1, characterized in that, The components of the carbon steel sheath in step 2 include the sheath base, the sheath body, and the sheath cover. When preparing the carbon steel sheath, the dimensions of the carbon steel sheath are designed according to the dimensional requirements of the TiAl alloy components, while leaving machining allowance for the TiAl alloy components.

4. The method for eliminating interdiffusion between carbon steel cladding and TiAl alloy using a chemical oxidation process according to claim 1, characterized in that, Step 3 specifically involves placing each component of the carbon steel sheath in an oil removal tank at 80-90°C for oil removal treatment. The oil removal tank is filled with an oil removal agent solution and heated at high temperature for 20-30 minutes. After the oil removal is completed, the surface of each component of the carbon steel sheath is washed with running water to remove the oil removal agent solution.

5. The method for eliminating interdiffusion between carbon steel cladding and TiAl alloy using a chemical oxidation process according to claim 4, characterized in that, The degreasing agent solution includes the following types: The first type: NaOH, Na2CO3 and water, with a weight ratio of NaOH, Na2CO3 and water of 5~6:7~8:100; The second type: NaOH, Na2CO3, Na3PO4, Na2SiO3 and water, with a weight ratio of 130:50:50:4:1000. The third type: Na2CO3, NaOH, trisodium pyrophosphate, Na2SiO3, Na3PO4 and water, with a weight ratio of 2:1:1:2:10:

200.

6. The method for eliminating interdiffusion between carbon steel cladding and TiAl alloy using a chemical oxidation process according to claim 3, characterized in that, Step 7 specifically involves welding the bottom of the sheath, the body of the sheath, and the cover of the sheath together, and then welding the KF25 vacuum connector to the top of the cover of the sheath as a powder inlet. Argon arc welding is used during welding. In step 8, the welded carbon steel sheath is leak-tested, and any leaking carbon steel sheaths need to be re-welded.

7. The method for eliminating interdiffusion between carbon steel cladding and TiAl alloy using a chemical oxidation process according to claim 1, characterized in that, Step 9 specifically involves placing the carbon steel sheath on a vibration platform at a vibration frequency of 20-40 Hz. While vibrating, TiAl alloy powder is added. When the TiAl alloy powder inside the carbon steel sheath stops falling after vibrating for 20-30 minutes, it indicates that the powder is full.

8. The method for eliminating interdiffusion between carbon steel cladding and TiAl alloy using a chemical oxidation process according to claim 6, characterized in that, The specific method for degassing the carbon steel sheath in step 10 is as follows: Step 10-1: Weld an exhaust pipe to the vacuum joint of the carbon steel sheath, connect the carbon steel sheath to the degassing machine through the exhaust pipe, and place it into the heating furnace; Step 10-2: Degas using a mechanical pump at room temperature until the internal pressure of the carbon steel sheath drops below 10 Pa; Step 10-3: Pumping down using diffusion pump at room temperature until the pressure inside the carbon steel can is reduced to 10 -2 Pa -3 ​ Step 10-4: Raise the temperature to 150~200℃ and hold for 1~2 hours; raise the temperature to 250~300℃ and hold for 2~3 hours; raise the temperature to 400~500℃ and hold for 4~5 hours. Step 10-5: Seal and weld the exhaust pipe of the carbon steel sheath, and remove it from the heating furnace to obtain a sealed carbon steel sheath.

9. The method for eliminating interdiffusion between carbon steel cladding and TiAl alloy using a chemical oxidation process according to claim 1, characterized in that, The airtightness test method in step 11 is as follows: after the sealing welding is completed, the sealed carbon steel sleeve is placed in hot water at 70~80℃. If no bubbles emerge from the surface of the sleeve within 10~15 minutes, it indicates that the airtightness of the sealed carbon steel sleeve is qualified. The temperature of the hot isostatic pressing densification treatment is 1200~1300℃, the time is 3~6 hours, and the pressure is 100~150MPa.

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