Method for preventing oxidation and metal element volatilization during high-temperature heat treatment of gamma-TiAl alloy and application thereof
By spraying a coating suspension of Al2O3, Y2O3, ZrO2, SiO2 and silica sol onto the surface of γ-TiAl alloy parts, an anti-oxidation protective layer is formed, which solves the oxidation and volatilization problems of γ-TiAl alloy during high-temperature heat treatment, and achieves efficient part performance and cost control.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SINO EURO MATERIALS TECH OF XIAN CO LTD
- Filing Date
- 2026-03-30
- Publication Date
- 2026-05-29
AI Technical Summary
γ-TiAl alloys are prone to oxidation and volatilization of metal elements during high-temperature heat treatment, leading to equipment damage and performance degradation, which is difficult to effectively solve with existing technologies.
A mixed coating suspension of Al2O3, Y2O3, ZrO2, SiO2 and silica sol is sprayed onto the surface of γ-TiAl alloy parts, followed by drying and heat treatment to form a dense antioxidant protective layer that isolates air and prevents oxidation and volatilization.
This method achieves a fine, fully lamellar microstructure in γ-TiAl alloy parts, avoiding oxidation and element volatilization problems, maintaining the performance and dimensional accuracy of the parts, and reducing production costs and equipment complexity.
Smart Images
Figure CN122105284A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of high-temperature protection technology for metallic materials, specifically relating to a method and its application for preventing oxidation and volatilization of metallic elements during high-temperature heat treatment of γ-TiAl alloys. Background Technology
[0002] γ-TiAl alloys possess low density, high specific strength, high creep resistance, and good oxidation and flame retardant properties. Their specific strength is approximately 1.5 times that of high-temperature alloys, their density is half that of high-temperature alloys, and their operating temperature can reach 650-750℃. Therefore, in the aerospace field, γ-TiAl alloys have the potential to replace some traditional high-temperature alloys for the manufacture of components such as low-pressure turbine blades and grids.
[0003] γ-TiAl alloys are intermetallic compounds with high brittleness. The main preparation methods include casting, hot isostatic pressing (HIP), and additive manufacturing. γ-TiAl alloy parts formed by HIP and additive manufacturing require heat treatment to obtain a fine, fully lamellar microstructure to achieve optimal overall performance. The phase transformation temperature of γ-TiAl alloys is generally above 1300℃, resulting in high heat treatment temperatures. Vacuum heat treatment technology leads to severe volatilization of low-saturated vapor pressure elements in the γ-TiAl alloy. These volatilized alloying elements deposit in the heat treatment equipment, damaging the insulation between the resistance wire and the insulating material, and causing equipment damage. On the other hand, atmospheric heat treatment furnaces cause the γ-TiAl alloy to react with oxygen at high temperatures, forming a millimeter-scale oxide layer. This method is only suitable for heat-treated samples and not for preparing γ-TiAl alloy parts.
[0004] Therefore, there is an urgent need to develop a method to prevent oxidation and volatilization of metal elements during high-temperature heat treatment of γ-TiAl alloys. Summary of the Invention
[0005] The purpose of this invention is to overcome the shortcomings of the prior art and to propose a method and its application for preventing oxidation and volatilization of metal elements during high-temperature heat treatment of γ-TiAl alloys. This method allows γ-TiAl alloy parts to achieve a fine, fully lamellar structure using conventional atmospheric heat treatment techniques, avoiding the element volatilization problems during vacuum heat treatment and the severe oxidation problems during atmospheric heat treatment.
[0006] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, the present invention discloses a method for preventing oxidation and volatilization of metal elements during high-temperature heat treatment of γ-TiAl alloys, comprising the following steps: Step 1: Mix Al2O3, Y2O3, ZrO2, SiO2, silica sol and ethanol in a specific ratio to obtain a coating suspension; Step 2: Grind the surface of the γ-TiAl alloy part, and then spray the coating suspension onto its surface to obtain the coating-modified γ-TiAl alloy part; Step 3: The coated modified γ-TiAl alloy parts are dried and heat-treated in sequence, and then air-cooled to obtain the finished γ-TiAl alloy parts.
[0007] Specifically, Al2O3, Y2O3, ZrO2 and SiO2 have the characteristics of strong temperature resistance, stable chemical properties (does not react with γ-TiAl alloy) and strong oxidation resistance; the silica sol is a binder phase, which can reduce the tension of the coating suspension and promote the coating suspension to form a film on the surface of the γ-TiAl alloy part, effectively isolating it from the outside air.
[0008] The ethanol can promote the mixing of Al2O3, Y2O3, ZrO2, SiO2 and silica sol, and accelerate the film formation rate of the coating suspension on the surface of the γ-TiAl alloy part.
[0009] More specifically, the microstructure of the γ-TiAl alloy finished product is a full lamellar structure, and the thickness of the surface oxide layer is less than 50 μm.
[0010] Further, in step 1, the coating suspension contains Al2O3 at a mass percentage of 5-10 wt%, Y2O3 at a mass percentage of 5-10 wt%, ZrO2 at a mass percentage of 5-10 wt%, SiO2 at a mass percentage of 10-15 wt%, silica sol at a mass percentage of 55-65 wt%, and ethanol at a mass percentage of 5-10 wt%.
[0011] Furthermore, in step 1, the particle size of Al2O3, Y2O3, ZrO2 and SiO2 is 1-50 nm.
[0012] Specifically, the particle size is limited to the nanometer scale to enhance the density and antioxidant capacity of the coating suspension.
[0013] Specifically, the ethanol is industrial ethanol with a concentration of 95% to 99.9%.
[0014] Specifically, the solid content of the silica sol is 20% to 30%.
[0015] Furthermore, in step 2, the grinding tool for the γ-TiAl alloy part is a grinding wheel.
[0016] Specifically, the grinding wheel is preferably 60 mesh.
[0017] Furthermore, in step 2, the surface roughness Ra of the γ-TiAl alloy part after polishing is ≥6.3μm.
[0018] Specifically, when the surface roughness Ra≥6.3μm, a micro-uneven structure can be formed on the surface of the γ-TiAl alloy part, thereby increasing the bonding force between the coating suspension and the surface of the γ-TiAl alloy part, making it easier for a complete coating to be formed on the surface of the γ-TiAl alloy part, achieving the effect of completely isolating air.
[0019] Furthermore, in step 3, the drying temperature of the coating-modified γ-TiAl alloy part is 50-80℃ and the drying time is 20-40min.
[0020] Furthermore, in step 3, the coating suspension is dried to form a dry coating film, and the thickness of the dry coating film is ≤0.5mm.
[0021] Specifically, preventing the coating dry film from being too thick is to avoid cracking or peeling of the coating dry film.
[0022] More specifically, the coated γ-TiAl alloy parts must be completely covered by the dry coating film to ensure that a continuous and dense antioxidant protective layer is formed on the surface of the coated γ-TiAl alloy parts after drying.
[0023] Furthermore, in step 3, the heat treatment process is carried out in an atmospheric heat treatment device.
[0024] Furthermore, in step 3, the temperature of the heat treatment process is 1300-1400℃, and the holding time is 1-3h.
[0025] Specifically, since the SiO2 softens in the temperature range of 700-1400℃, when the heat treatment process temperature is 1300-1400℃, the dry coating film softens into a viscous semi-solid. This viscous semi-solid can effectively isolate the outside air and improve the oxidation resistance of the coated modified γ-TiAl alloy parts after drying.
[0026] Secondly, any of the above-mentioned methods for preventing oxidation and volatilization of metal elements in γ-TiAl alloys during high-temperature heat treatment disclosed in this invention are applied in the manufacture of turbine blades or grid components.
[0027] Compared with the prior art, the present invention has the following beneficial effects: I. This invention enables γ-TiAl alloy parts to obtain a fine, fully lamellar structure. Under the premise of achieving optimal comprehensive performance of the alloy, it solves the problem of alloy element volatilization during vacuum heat treatment of γ-TiAl alloy parts, avoiding the impact of alloy element volatilization on the chemical composition and microstructure of the workpiece surface, and preventing the decline of the mechanical and chemical properties of the workpiece. On the other hand, it solves the oxidation problem of γ-TiAl alloy parts during atmospheric heat treatment, avoiding loss of surface smoothness and out-of-tolerance dimensional accuracy.
[0028] Second, this invention utilizes conventional atmospheric heat treatment equipment to achieve high-temperature heat treatment of γ-TiAl alloy parts. Compared to heat treatment of γ-TiAl alloy parts in a vacuum heat treatment furnace, it eliminates the need for a complex vacuum system, resulting in relatively low equipment costs. Furthermore, atmospheric heat treatment furnaces do not require maintaining a high vacuum, leading to lower power consumption. Additionally, atmospheric heat treatment furnaces have lower requirements for the protective gas inside the furnace, eliminating the need for high-purity inert gases and reducing operating costs. Therefore, this invention not only ensures that γ-TiAl alloy parts prepared in an atmospheric heat treatment furnace meet usage standards but also significantly reduces production costs. Attached Figure Description
[0029] The accompanying drawings are incorporated in and form part of this specification, and together with the description serve to explain the principles of the invention.
[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0031] Figure 1 The above is the total EDS spectrum of the γ-TiAl alloy parts of this invention. Figure 2 This is a secondary electronic image of the finished γ-TiAl alloy part in Example 1 of the present invention; Figure 3 This is a secondary electronic image of the γ-TiAl alloy component in Example 2 of the present invention; Figure 4 This is a secondary electronic image of the γ-TiAl alloy component in Example 3 of the present invention; Figure 5 This is a secondary electronic image of the γ-TiAl alloy component in Example 4 of the present invention; Figure 6 This is a secondary electronic image of the γ-TiAl alloy component in Example 5 of the present invention; Figure 7The image shows a secondary electron image of a γ-TiAl alloy part without the present invention coated under atmospheric heat treatment technology. Figure 8 The condition of the bottom surface of the vacuum heat treatment furnace before processing γ-TiAl alloy parts; Figure 9 The condition of the bottom surface of the vacuum heat treatment furnace after processing γ-TiAl alloy parts; Figure 10 This is a flowchart of the preparation method of the present invention. Detailed Implementation
[0032] Exemplary embodiments will now be described in detail. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples consistent with some aspects of the invention as detailed in the appended claims.
[0033] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.
[0034] Example 1 like Figure 10 As shown, this embodiment provides a method for preventing oxidation and volatilization of metal elements during high-temperature heat treatment of γ-TiAl alloys, including the following steps: Step 1: Mix Al2O3, Y2O3, ZrO2, SiO2, silica sol and ethanol in a specific ratio to obtain a coating suspension.
[0035] Specifically, the mass percentages of Al2O3, Y2O3, ZrO2, SiO2, silica sol, and ethanol are 8 wt%, 8 wt%, 8 wt%, 11 wt%, 58 wt%, and 7 wt%, respectively; the particle sizes of Al2O3, Y2O3, ZrO2, and SiO2 are all 1-50 nm.
[0036] More specifically, the concentration of the ethanol is 99%; the solid content of the silica sol is 25%.
[0037] Step 2: Grind the surface of the γ-TiAl alloy part, and then spray the coating suspension onto its surface to obtain the coating-modified γ-TiAl alloy part.
[0038] Specifically, a 60-mesh grinding wheel is used for the grinding process, and the surface roughness Ra of the γ-TiAl alloy part after grinding is ≥6.3μm.
[0039] Specifically, the coating suspension spraying process should ensure that the surface of the γ-TiAl alloy part is completely covered and the spraying thickness is basically consistent.
[0040] Step 3: The coated modified γ-TiAl alloy parts are dried and heat-treated in sequence, and then air-cooled to obtain the finished γ-TiAl alloy parts.
[0041] Specifically, the coated γ-TiAl alloy part is placed in an oven to dry at a temperature of 70°C for 30 minutes. During this time, the coating suspension becomes a dry coating film, resulting in the dried coated γ-TiAl alloy part. The dried coated γ-TiAl alloy part must be completely covered by the dry coating film, and the coating thickness must be ≤0.5mm. If there are any missing parts of the coating, the spraying and drying steps in step 3 are repeated.
[0042] Specifically, the dried coating-modified γ-TiAl alloy part is heat-treated in an atmospheric heat treatment equipment at a temperature of 1300℃ for 3 hours; then air-cooled to room temperature to obtain the finished γ-TiAl alloy part with a full lamellar structure and a surface oxide layer thickness of less than 50μm.
[0043] Example 2 The preparation method in this embodiment is the same as that in Example 1, except that: In step 1, the mass percentages of Al2O3 are 8wt%, Y2O3 is 6wt%, ZrO2 is 6wt%, SiO2 is 12wt%, silica sol is 60wt%, and ethanol is 8wt%.
[0044] The concentration of the ethanol is 96%; the solid content of the silica sol is 30%.
[0045] In step 3, the drying temperature of the coating-modified γ-TiAl alloy part is 60℃ and the drying time is 40min; the heat treatment temperature of the dried coating-modified γ-TiAl alloy part in the atmospheric heat treatment equipment is 1350℃ and the holding time is 2h.
[0046] Example 3 The preparation method in this embodiment is the same as that in Example 1, except that: In step 1, the mass percentages of Al2O3 are 9wt%, Y2O3 are 7wt%, ZrO2 are 6wt%, SiO2 are 13wt%, silica sol is 57wt%, and ethanol is 8wt%.
[0047] The concentration of the ethanol is 97%; the solid content of the silica sol is 20%.
[0048] In step 3, the drying temperature of the coating-modified γ-TiAl alloy part is 80℃ and the drying time is 40min; the heat treatment temperature of the dried coating-modified γ-TiAl alloy part in the atmospheric heat treatment equipment is 1380℃ and the holding time is 2h.
[0049] Example 4 The preparation method in this embodiment is the same as that in Example 1, except that: In step 1, the mass percentages of Al2O3, Y2O3, ZrO2, SiO2, silica sol, and ethanol are 6wt%, 6wt%, 6wt%, 63wt%, and 9wt%, respectively.
[0050] In step 3, the drying temperature of the coating-modified γ-TiAl alloy part is 80℃ and the drying time is 25min; the heat treatment temperature of the dried coating-modified γ-TiAl alloy part in the atmospheric heat treatment equipment is 1400℃ and the holding time is 1.2h.
[0051] Example 5 The preparation method in this embodiment is the same as that in Example 1, except that: In step 1, the mass percentages of Al2O3 are 5wt%, Y2O3 is 10wt%, ZrO2 is 10wt%, SiO2 is 14wt%, silica sol is 55wt%, and ethanol is 6wt%.
[0052] In step 3, the drying temperature of the coating-modified γ-TiAl alloy part is 50℃ and the drying time is 40min; the heat treatment temperature of the dried coating-modified γ-TiAl alloy part in the atmospheric heat treatment equipment is 1330℃ and the holding time is 2h.
[0053] To verify the effectiveness of this invention, two comparative examples are also provided in this specification, as follows: Comparative Example 1 The γ-TiAl alloy parts were directly placed in an atmospheric heat treatment furnace for heat treatment at a temperature of 1330°C for 3 hours. Subsequently, the heat-treated γ-TiAl alloy parts were air-cooled to room temperature to obtain the final γ-TiAl alloy parts.
[0054] Comparative Example 2 The γ-TiAl alloy part was placed in a vacuum heat treatment furnace, and the heat treatment temperature was 1350℃, and the holding time was 2h.
[0055] To make the objectives, technical solutions, and advantages of this invention clearer, microscopic examination was performed on the γ-TiAl alloy parts prepared in Examples 1-5, Comparative Example 1, and Comparative Example 2. The specific results are as follows: like Figure 1 As shown, the elemental characteristic peak intensities of Al and Ti are extremely high, indicating that the alloy components used in this invention are γ-TiAl alloys.
[0056] like Figures 2-6 The images shown are secondary electron images of the γ-TiAl alloy parts prepared in Examples 1-5. As can be seen from each image, the left side of the image shows a rough, porous dark area with weak secondary electron signals, indicating an oxide layer. Comparing the oxide layer thickness with the image scale reveals that the oxide layer thickness on the surface of the γ-TiAl alloy parts in Examples 1-5 is less than 50 μm. The central area of the images shows oriented lamellar and layered structures, a typical morphological representation of a fully lamellar microstructure.
[0057] like Figure 7 As shown, when heat treating γ-TiAl alloy parts in an atmospheric heat treatment furnace, if the coating suspension provided by this invention is not applied, the oxide layer thickness on the surface of the heat-treated γ-TiAl alloy parts is on the order of millimeters.
[0058] like Figure 8 , Figure 9 As shown, after heat treatment of γ-TiAl alloy parts in a vacuum heat treatment furnace, the bottom surface of the furnace chamber turns a bright metallic color ( Figure 8 (As shown) became dull and black ( Figure 9 As shown in the figure, the obvious deposition phenomenon in the furnace indicates that the alloying elements in the γ-TiAl alloy are volatilizing, which will damage the vacuum heat treatment furnace.
[0059] Therefore, it can be concluded that the present invention can effectively solve the oxidation of γ-TiAl alloy parts and the volatilization of alloying elements in γ-TiAl alloy in vacuum heat treatment furnace, while ensuring that γ-TiAl alloy parts obtain a full lamellar structure.
[0060] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention.
[0061] It should be understood that the present invention is not limited to the content already described above, and various modifications and changes can be made without departing from its scope. The scope of the present invention is limited only by the appended claims.
Claims
1. A method for preventing oxidation and volatilization of metal elements during high-temperature heat treatment of γ-TiAl alloys, characterized in that, Includes the following steps: Step 1: Mix Al2O3, Y2O3, ZrO2, SiO2, silica sol and ethanol in a specific ratio to obtain a coating suspension; Step 2: Grind the surface of the γ-TiAl alloy part, and then spray the coating suspension onto its surface to obtain the coating-modified γ-TiAl alloy part; Step 3: The coated modified γ-TiAl alloy parts are dried and heat-treated in sequence, and then air-cooled to obtain the finished γ-TiAl alloy parts.
2. The method for preventing oxidation and volatilization of metal elements during high-temperature heat treatment of γ-TiAl alloys according to claim 1, characterized in that, Step 1: In the coating suspension, the mass percentages of Al2O3, Y2O3, ZrO2, SiO2, silica sol, and ethanol are 5-10 wt%.
3. The method for preventing oxidation and volatilization of metal elements during high-temperature heat treatment of γ-TiAl alloys according to claim 1, characterized in that, In step 1, the particle size of Al2O3, Y2O3, ZrO2 and SiO2 is 1-50nm.
4. The method for preventing oxidation and volatilization of metal elements during high-temperature heat treatment of γ-TiAl alloys according to claim 1, characterized in that, In step 2, the grinding tool for the γ-TiAl alloy part is a grinding wheel.
5. The method for preventing oxidation and volatilization of metal elements during high-temperature heat treatment of γ-TiAl alloys according to claim 1, characterized in that, In step 2, the surface roughness of the γ-TiAl alloy part after polishing is Ra≥6.3μm.
6. The method for preventing oxidation and volatilization of metal elements during high-temperature heat treatment of γ-TiAl alloys according to claim 1, characterized in that, In step 3, the drying temperature of the coating-modified γ-TiAl alloy part is 50-80℃ and the drying time is 20-40min.
7. The method for preventing oxidation and volatilization of metal elements during high-temperature heat treatment of γ-TiAl alloys according to claim 1, characterized in that, In step 3, the coating suspension is dried to form a dry coating film with a thickness of ≤0.5mm.
8. The method for preventing oxidation and volatilization of metal elements during high-temperature heat treatment of γ-TiAl alloys according to claim 1, characterized in that, In step 3, the heat treatment process is carried out in an atmospheric heat treatment device.
9. The method for preventing oxidation and volatilization of metal elements during high-temperature heat treatment of γ-TiAl alloys according to claim 1, characterized in that, In step 3, the temperature of the heat treatment process is 1200-1400℃, and the holding time is 1-3h.
10. A method for preventing oxidation and volatilization of metal elements during high-temperature heat treatment of γ-TiAl alloys according to any one of claims 1-9, applied in the manufacture of turbine blades or grid components.