A high-temperature oxidation-resistant coating suitable for TiAl alloy and a preparation method thereof

Abstract

The application discloses a high-temperature oxidation-resistant coating suitable for a TiAl alloy and a preparation method thereof. a Al b Cr c Nb d Si e Y f multi-element alloy target; three, performing plasma etching on the prepared TiAl alloy substrate; and four, obtaining the TiAl alloy with the surface-deposited Ti-Al-Cr-Nb-Si-Y high-temperature oxidation-resistant coating by using multi-arc ion plating. The Ti-Al-Cr-Nb-Si-Y coating is prepared on the surface of the TiAl alloy by using the multi-arc ion plating process, the coating is uniform and dense, is well combined with the TiAl alloy substrate, has high hardness, has good high-temperature oxidation resistance, and the preparation process is simple, has high operability, is low in production cost, and is beneficial to large-scale industrial application.

Description

Technical Field

[0001] This invention belongs to the field of high-temperature antioxidant coating preparation technology, specifically relating to a high-temperature antioxidant coating suitable for TiAl alloys and its preparation method. Background Technology

[0002] Titanium-aluminum alloys possess advantages such as low density, high elastic modulus, high specific strength, high corrosion resistance, good high-temperature oxidation resistance, and good creep resistance, making them widely used in aerospace materials. However, their limited oxidation resistance hinders further applications when operating at temperatures above 800°C. Currently, common solutions include alloying and surface coating to improve the high-temperature oxidation resistance of titanium-aluminum alloys. However, alloying methods involve long research cycles, large workloads, high research costs, and significant risks. Furthermore, overall alloying can severely impact the alloy's overall mechanical properties, particularly increasing brittleness and reducing fatigue performance. Therefore, it is necessary to prepare coatings on the surface of titanium-aluminum alloys to improve their high-temperature oxidation resistance.

[0003] Currently, the main methods for preparing high-temperature anti-oxidation coatings on TiAl alloy surfaces include diffusion infiltration, laser cladding, dual-glow plasma metallization, atmospheric plasma spraying, and physical vapor deposition. Diffusion infiltration coatings have a low deposition rate, long preparation time, and high reaction temperature, which may affect the substrate microstructure. Laser cladding, due to the large temperature difference near the molten pool, results in poor coating adhesion and is prone to cracking and peeling. Dual-glow plasma metallization requires sophisticated equipment and is not suitable for processing parts with complex dimensions. Atmospheric plasma spraying involves high-speed impact of powder materials in a molten or semi-molten state onto the workpiece, resulting in unavoidable porosity and cracks between powder particles. Physical vapor deposition can deposit coating materials onto the substrate surface through processes such as evaporation and sputtering. This method can obtain high-density, low-porosity coatings with controllable thickness. Multi-arc ion plating technology, in particular, involves ionizing gas or evaporated material under vacuum through gas discharge. The evaporated material or its reactants are deposited onto the part to be plated when bombarded at high speed by the gas ions or evaporated material ions. Multi-arc ion plating technology allows for simultaneous sputtering cleaning and film deposition, effectively reducing internal stress in the thin film, resulting in a denser film with strong adhesion, good coating flexibility, and a high deposition rate. Furthermore, multi-arc ion plating equipment is simple, the process is highly repeatable, and the composition and thickness of the coating can be precisely controlled. Therefore, using multi-arc ion plating technology to prepare coatings on TiAl alloys holds promise as an effective method to improve their high-temperature oxidation resistance, further enabling the high-temperature service life of TiAl alloys. Summary of the Invention

[0004] The technical problem to be solved by this invention is to provide a method for preparing a high-temperature anti-oxidation coating suitable for TiAl alloys, addressing the shortcomings of the prior art. This method employs a multi-arc ion plating process to prepare a Ti-Al-Cr-Nb-Si-Y coating on the surface of TiAl alloys. This coating has a uniform and dense structure, good adhesion to the TiAl alloy substrate, high hardness, and excellent high-temperature anti-oxidation properties, thus overcoming the shortcomings of existing high-temperature anti-oxidation coating preparation processes on TiAl alloy surfaces, such as poor adhesion, easy peeling, and impact on the substrate microstructure.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a method for preparing a high-temperature anti-oxidation coating suitable for TiAl alloys, characterized in that the method includes the following steps:

[0006] Step 1: Pre-fabrication of TiAl alloy substrate: After finishing the surface of TiAl alloy, polish it, then clean it until there are no dust, oil stains, water stains or other impurities on the surface, and then wash and dry it to obtain the pre-fabricated TiAl alloy substrate.

[0007] Step 2, Preparation of Multi-element Alloy Target Material: Prepare Ti a Al b Cr c Nb d Si e Y f A multi-element alloy target is installed on the cathode target position in the vacuum chamber of a multi-arc ion plating equipment, where a, b, c, d, e, and f represent the atomic percentages of the corresponding elements, and a+b+c+d+e+f=1, 0.1≤a≤0.3, 0.5≤b≤0.6, 0.1≤c≤0.16, 0.03≤d≤0.04, 0.05≤e≤0.10, and f≈0.01.

[0008] Step 3, Substrate Etching: The TiAl alloy substrate prefabricated in Step 1 is placed on the substrate containing Ti in Step 2. a Al b Cr c Nb d Si e Y f On the vacuum chamber support of the multi-alloy target, a vacuum is drawn to ensure that the pressure inside the vacuum chamber does not exceed 5 × 10⁻⁶. - 3 Pa, turn on the high-frequency plasma power supply, then introduce H2 to adjust the pressure in the vacuum chamber to 0.5Pa~2Pa, then apply a bias voltage to the pre-fabricated TiAl alloy substrate, and the resulting electric field performs plasma etching on the TiAl alloy substrate to remove the oxide impurities on the surface. Then stop introducing H2, introduce Ar gas to adjust the pressure in the vacuum chamber to 0.5Pa~2Pa, and continue to perform plasma etching on the TiAl alloy substrate.

[0009] Step 4, Multi-element coating deposition: An external electric field is applied to the TiAl alloy substrate etched by Ar gas plasma in Step 3, and argon gas is introduced into the vacuum chamber to adjust the vacuum level. Then, the cathode target arc is started to perform multi-arc ion plating to obtain a TiAl alloy with a Ti-Al-Cr-Nb-Si-Y high-temperature anti-oxidation coating deposited on the surface.

[0010] The above-mentioned method for preparing a high-temperature anti-oxidation coating suitable for TiAl alloys is characterized in that the finishing process in step one involves precision milling of the TiAl alloy surface using a machining center. This finishing operation reduces the difficulty of subsequent polishing and is suitable for batch substrate processing.

[0011] The above-mentioned method for preparing a high-temperature anti-oxidation coating suitable for TiAl alloys is characterized in that the cleaning process in step one is as follows: firstly, an industrial degreasing cleaning agent is used for degreasing cleaning, and then deionized water and ethanol solution are used in sequence for ultrasonic cleaning at 25℃~40℃ for 15min~20min respectively.

[0012] The above-mentioned method for preparing a high-temperature anti-oxidation coating suitable for TiAl alloys is characterized in that, in step three, the high-frequency plasma power supply is turned on and the plasma voltage is controlled at 200V~500V, the vacuum chamber temperature is 200℃~400℃, the substrate bias voltage is set to 40V~60V and the etching time is 10min when H2 is introduced for plasma etching, and the substrate bias voltage is set to 200V~600V and the etching time is 30min~60min when Ar gas is introduced for plasma etching.

[0013] A plasma power source generates plasma. By applying a bias voltage, the directional impact of the plasma on the TiAl alloy substrate is increased. Under the combined effect of these two factors, plasma etching is performed on the TiAl alloy substrate, which facilitates the formation of micro- and nano-structures on the substrate surface that are conducive to coating adhesion. Specifically, H2 is first introduced with a lower bias voltage. The reduction effect of H2 is used to perform plasma etching at a higher temperature to remove oxides and other impurities from the surface of the TiAl alloy substrate. Then, Ar gas is introduced and the bias voltage applied to the substrate surface is increased to perform plasma etching at a greater depth on the TiAl alloy substrate, forming nano-sized microstructures that are conducive to coating adhesion and improving the bonding force between the high-temperature anti-oxidation coating and the TiAl alloy substrate.

[0014] The above-mentioned method for preparing a high-temperature anti-oxidation coating suitable for TiAl alloys is characterized in that, in step four, the voltage of the applied external electric field is -100V to -350V, the vacuum degree is adjusted to 0.5Pa to 2Pa, the cathode arc current generated by the cathode target arc is 50A to 120A, the temperature of the multi-arc ion plating is maintained at 150℃ to 400℃, and the time is 20min to 80min.

[0015] Meanwhile, the present invention also discloses a high-temperature anti-oxidation coating suitable for TiAl alloys, characterized in that it is prepared by the above-described method.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] 1. This invention employs a multi-arc ion plating process to prepare a high-temperature anti-oxidation coating on the surface of TiAl alloy, using Ti... a Al b Cr c Nb d Si e Y f Using multi-element alloys as the target material, a Ti-Al-Cr-Nb-Si-Y coating was successfully deposited on the surface of a TiAl alloy substrate. The coating has a uniform and dense structure, good adhesion to the substrate, and a hardness of up to 900 HV, which is 80% higher than that of the substrate.

[0018] 2. This invention uses Ti a Al b Cr c Nb d Si e Y f A Ti-Al-Cr-Nb-Si-Y coating is deposited on the surface of a TiAl alloy substrate using a multi-element alloy as the target material. The appropriate proportions of Al, Cr, Si, and Nb ensure the formation of a dense and continuous Al2O3 film on the coating surface, while also inhibiting the competitive oxidation of Ti. The introduction of Si element improves the toughness of the coating, while the addition of trace element Y increases the viscosity of the coating and improves the bonding strength between the coating and the substrate, thereby ensuring that the Ti-Al-Cr-Nb-Si-Y coating has good high-temperature oxidation resistance. Finally, after being oxidized at 850℃ for 600 hours, the Ti-Al-Cr-Nb-Si-Y coating prepared by this invention showed a weight gain rate per unit area that was more than 60% lower than that of the substrate without coating, and there was no peeling or flaking phenomenon (the substrate without coating showed obvious peeling and flaking after 5 hours of oxidation), demonstrating good high-temperature oxidation resistance.

[0019] 3. In this invention, the TiAl alloy substrate is pretreated by plasma etching before depositing the Ti-Al-Cr-Nb-Si-Y coating to form a nanostructure on the substrate surface. This microstructure improves the adhesion between the surface coating and the substrate through gripping action.

[0020] 4. In the process of prefabricating TiAl alloy substrate, the present invention uses a machining center to perform precision milling on TiAl alloy samples and then polishing them, which reduces the difficulty and time of subsequent manual polishing. It is suitable for batch processing of substrates and significantly reduces polishing time compared to the conventional method of starting with manual polishing.

[0021] 5. The preparation process of the present invention is simple, highly operable, and has low production cost, which is conducive to large-scale industrial application.

[0022] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0023] Figure 1 The image shows the EDS energy spectrum of the Ti-Al-Cr-Nb-Si-Y high-temperature antioxidant coating prepared in Example 1 of this invention.

[0024] Figure 2 The image shows the surface SEM morphology of the Ti-Al-Cr-Nb-Si-Y high-temperature antioxidant coating prepared in Example 1 of this invention.

[0025] Figure 3 The graphs show the weight changes of TiAl alloys with Ti-Al-Cr-Nb-Si-Y high-temperature anti-oxidation coating and TiAl alloys without coating prepared by 600h isothermal oxidation in Examples 5-6 of this invention.

[0026] Figure 4 This is a macroscopic photograph of the TiAl alloy substrate and the TiAl alloy with a Ti-Al-Cr-Nb-Si-Y high-temperature anti-oxidation coating deposited on the surface after 600 hours of high-temperature oxidation, as used in Example 6 of this invention. Detailed Implementation

[0027] Example 1

[0028] This embodiment includes the following steps:

[0029] Step 1: Pre-fabrication of TiAl alloy substrate: The TiAl alloy surface is precision milled and polished using a machining center. Then, it is cleaned until the surface is visually free of dust, oil, water stains, and other impurities, and then washed and dried to obtain the pre-fabricated TiAl alloy substrate. The cleaning process is as follows: first, an industrial degreasing cleaning agent is used for degreasing and cleaning, and then deionized water and ethanol solution are used in sequence for ultrasonic cleaning at 25℃~40℃ for 15 minutes each.

[0030] Step 2, Preparation of Multi-element Alloy Target Material: Prepare Ti 0.1 Al 0.6 Cr 0.16 Nb 0.03 Si 0.1 Y 0.01A multi-element alloy target is installed on the cathode target position in the vacuum chamber of a multi-arc ion plating equipment;

[0031] Step 3, Substrate Etching: The TiAl alloy substrate prefabricated in Step 1 is placed on the substrate containing Ti in Step 2. 0.1 Al 0.6 Cr 0.16 Nb 0.03 Si 0.1 Y 0.01 On the vacuum chamber support of the multi-alloy target, a vacuum is drawn to ensure that the pressure inside the vacuum chamber does not exceed 5 × 10⁻⁶. -3 Pa, turn on the high-frequency plasma power supply, control the plasma voltage to 200V, then introduce H2 to adjust the pressure in the vacuum chamber to 1Pa, control the vacuum chamber temperature to 200℃, then apply a base bias voltage of 40V to the pre-fabricated TiAl alloy substrate, and the resulting electric field performs plasma etching on the TiAl alloy substrate for 10min to remove oxide impurities on its surface, then stop introducing H2, introduce Ar gas to adjust the pressure in the vacuum chamber to 1Pa, and use a base bias voltage of 500V to perform plasma etching on the TiAl alloy substrate for 40min;

[0032] Step 4, Multi-element Coating Deposition: An external electric field of -350V is applied to the TiAl alloy etched by Ar plasma in Step 3, and Argon gas is introduced into the vacuum chamber to adjust the vacuum degree to 0.5Pa. Then, the cathode target arc is started to perform multi-arc ion plating. The cathode arc current is 50A, the temperature of multi-arc ion plating is maintained at 150℃, and the time is 50min, to obtain a TiAl alloy with a Ti-Al-Cr-Nb-Si-Y high-temperature anti-oxidation coating deposited on the surface.

[0033] Figure 1 The above is the EDS energy spectrum of the Ti-Al-Cr-Nb-Si-Y high-temperature antioxidant coating prepared in this embodiment. Figure 1 It can be seen that the six elements contained in this Ti-Al-Cr-Nb-Si-Y high-temperature antioxidant coating are similar to Ti. 0.1 Al 0.6 Cr 0.16 Nb 0.03 Si 0. 1Y 0.01 The types of elements in the multi-element alloy target remain consistent.

[0034] Figure 2 The image shows the surface SEM morphology of the Ti-Al-Cr-Nb-Si-Y high-temperature antioxidant coating prepared in this embodiment. Figure 2 It can be seen that the structure of the Ti-Al-Cr-Nb-Si-Y high-temperature antioxidant coating is dense and uniform.

[0035] Example 2

[0036] This embodiment includes the following steps:

[0037] Step 1: Pre-fabrication of TiAl alloy substrate: The TiAl alloy surface is precision milled and polished using a machining center. Then, it is cleaned until the surface is visually free of dust, oil, water stains, and other impurities, and then washed and dried to obtain the pre-fabricated TiAl alloy substrate. The cleaning process is as follows: first, an industrial degreasing cleaning agent is used for degreasing and cleaning, and then deionized water and ethanol solution are used in sequence for ultrasonic cleaning at 25℃~40℃ for 20 minutes each.

[0038] Step 2, Preparation of Multi-element Alloy Target Material: Prepare Ti 0.1 Al 0.6 Cr 0.16 Nb 0.03 Si 0.1 Y 0.01 A multi-element alloy target is installed on the cathode target position in the vacuum chamber of a multi-arc ion plating equipment;

[0039] Step 3, Substrate Etching: The TiAl alloy substrate prefabricated in Step 1 is placed on the substrate containing Ti in Step 2. 0.1 Al 0.6 Cr 0.16 Nb 0.03 Si 0.1 Y 0.01 On the vacuum chamber support of the multi-alloy target, a vacuum is drawn to ensure that the pressure inside the vacuum chamber does not exceed 5 × 10⁻⁶. -3 Pa, turn on the high-frequency plasma power supply, control the plasma voltage to 400V, then introduce H2 to adjust the pressure in the vacuum chamber to 1Pa, control the vacuum chamber temperature to 300℃, then apply a base bias voltage of 40V to the pre-fabricated TiAl alloy substrate, and the resulting electric field performs plasma etching on the TiAl alloy substrate for 10min to remove oxide impurities on its surface, then stop introducing H2, introduce Ar gas to adjust the pressure in the vacuum chamber to 1Pa, and use a base bias voltage of 200V to perform plasma etching on the TiAl alloy substrate for 30min;

[0040] Step 4, Multi-element Coating Deposition: Apply an external electric field to -200V to the TiAl alloy etched by Ar plasma in Step 3, and introduce argon gas into the vacuum chamber to adjust the vacuum level to 1Pa. Then, start the cathode target arc for multi-arc ion plating. The cathode arc current is 100A, the temperature of multi-arc ion plating is maintained at 200℃, and the time is 20min to obtain a TiAl alloy with a Ti-Al-Cr-Nb-Si-Y high-temperature anti-oxidation coating deposited on the surface.

[0041] Example 3

[0042] This embodiment includes the following steps:

[0043] Step 1: Pre-fabrication of TiAl alloy substrate: The TiAl alloy surface is precision milled and polished using a machining center. Then, it is cleaned until the surface is visually free of dust, oil, water stains, and other impurities, and then washed and dried to obtain the pre-fabricated TiAl alloy substrate. The cleaning process is as follows: first, an industrial degreasing cleaning agent is used for degreasing and cleaning, and then deionized water and ethanol solution are used in sequence for ultrasonic cleaning at 25℃~40℃ for 15 minutes each.

[0044] Step 2, Preparation of Multi-element Alloy Target Material: Prepare Ti 0.1 Al 0.6 Cr 0.16 Nb 0.03 Si 0.1 Y 0.01 A multi-element alloy target is installed on the cathode target position in the vacuum chamber of a multi-arc ion plating equipment;

[0045] Step 3, Substrate Etching: The TiAl alloy substrate prefabricated in Step 1 is placed on the substrate containing Ti in Step 2. 0.1 Al 0.6 Cr 0.16 Nb 0.03 Si 0.1 Y 0.01 On the vacuum chamber support of the multi-alloy target, a vacuum is drawn to ensure that the pressure inside the vacuum chamber does not exceed 5 × 10⁻⁶. -3 Pa, turn on the high-frequency plasma power supply, control the plasma voltage to 300V, then introduce H2 to adjust the pressure in the vacuum chamber to 0.5Pa, control the vacuum chamber temperature to 300℃, then apply a 50V base bias voltage to the pre-fabricated TiAl alloy substrate, and the resulting electric field performs plasma etching on the TiAl alloy substrate for 10min to remove oxide impurities on its surface, then stop introducing H2, introduce Ar gas to adjust the pressure in the vacuum chamber to 0.5Pa, and use a 600V base bias voltage to perform plasma etching on the TiAl alloy substrate for 30min;

[0046] Step 4, Multi-element Coating Deposition: An external electric field of -100V is applied to the TiAl alloy etched by Ar plasma in Step 3, and Argon gas is introduced into the vacuum chamber to adjust the vacuum degree to 2Pa. Then, the cathode target arc is started to perform multi-arc ion plating. The cathode arc current is 120A, the temperature of multi-arc ion plating is maintained at 400℃, and the time is 80min, to obtain a TiAl alloy with a Ti-Al-Cr-Nb-Si-Y high-temperature anti-oxidation coating deposited on the surface.

[0047] Example 4

[0048] This embodiment includes the following steps:

[0049] Step 1: Pre-fabrication of TiAl alloy substrate: The TiAl alloy surface is precision milled and polished using a machining center. Then, it is cleaned until the surface is visually free of dust, oil, water stains, and other impurities, and then washed and dried to obtain the pre-fabricated TiAl alloy substrate. The cleaning process is as follows: first, an industrial degreasing cleaning agent is used for degreasing and cleaning, and then deionized water and ethanol solution are used in sequence for ultrasonic cleaning at 25℃~40℃ for 15 minutes each.

[0050] Step 2, Preparation of Multi-element Alloy Target Material: Prepare Ti 0.3 Al 0.5 Cr 0.1 Nb 0.04 Si 0.05 Y 0.01 A multi-element alloy target is installed on the cathode target position in the vacuum chamber of a multi-arc ion plating equipment;

[0051] Step 3, Substrate Etching: The TiAl alloy substrate prefabricated in Step 1 is placed on the substrate containing Ti in Step 2. 0.3 Al 0.5 Cr 0.1 Nb 0.04 Si 0.05 Y 0.01 On the vacuum chamber support of the multi-alloy target, a vacuum is drawn to ensure that the pressure inside the vacuum chamber does not exceed 5 × 10⁻⁶. -3 Pa, turn on the high-frequency plasma power supply, control the plasma voltage to 300V, then introduce H2 to adjust the pressure in the vacuum chamber to 2Pa, control the vacuum chamber temperature to 400℃, then apply a base bias voltage of 50V to the pre-fabricated TiAl alloy substrate, and the resulting electric field performs plasma etching on the TiAl alloy substrate for 15min to remove oxide impurities on its surface, then stop introducing H2, introduce Ar gas to adjust the pressure in the vacuum chamber to 2Pa, and use a base bias voltage of 300V to perform plasma etching on the TiAl alloy substrate for 60min;

[0052] Step 4, Multi-element Coating Deposition: An external electric field of -100V is applied to the TiAl alloy etched by Ar plasma in Step 3, and argon gas is introduced into the vacuum chamber to adjust the vacuum degree to 2Pa. Then, the cathode target arc is started to perform multi-arc ion plating. The cathode arc current is 120A, the temperature of multi-arc ion plating is maintained at 400℃, and the time is 30min, to obtain a TiAl alloy with a Ti-Al-Cr-Nb-Si-Y high-temperature anti-oxidation coating deposited on the surface.

[0053] Example 5

[0054] This embodiment includes the following steps:

[0055] Step 1: Pre-fabrication of TiAl alloy substrate: The TiAl alloy surface is precision milled and polished using a machining center. Then, it is cleaned until the surface is visually free of dust, oil, water stains, and other impurities, and then washed and dried to obtain the pre-fabricated TiAl alloy substrate. The cleaning process is as follows: first, an industrial degreasing cleaning agent is used for degreasing and cleaning, and then deionized water and ethanol solution are used in sequence for ultrasonic cleaning at 25℃~40℃ for 15 minutes each.

[0056] Step 2, Preparation of Multi-element Alloy Target Material: Prepare Ti 0.3 Al 0.5 Cr 0.1 Nb 0.04 Si 0.05 Y 0.01 A multi-element alloy target is installed on the cathode target position in the vacuum chamber of a multi-arc ion plating equipment;

[0057] Step 3, Substrate Etching: The TiAl alloy substrate prefabricated in Step 1 is placed on the substrate containing Ti in Step 2. 0.3 Al 0.5 Cr 0.1 Nb 0.04 Si 0.05 Y 0.01 On the vacuum chamber support of the multi-alloy target, a vacuum is drawn to ensure that the pressure inside the vacuum chamber does not exceed 5 × 10⁻⁶. -3 Pa, turn on the high-frequency plasma power supply, control the plasma voltage to 300V, then introduce H2 to adjust the pressure in the vacuum chamber to 2Pa, control the vacuum chamber temperature to 300℃, then apply a base bias voltage of 60V to the pre-fabricated TiAl alloy substrate, and the resulting electric field performs plasma etching on the TiAl alloy substrate for 20min to remove oxide impurities on its surface, then stop introducing H2, introduce Ar gas to adjust the pressure in the vacuum chamber to 2Pa, and use a base bias voltage of 500V to perform plasma etching on the TiAl alloy substrate for 30min;

[0058] Step 4, Multi-element Coating Deposition: An external electric field of -200V is applied to the TiAl alloy etched by Ar plasma in Step 3, and argon gas is introduced into the vacuum chamber to adjust the vacuum degree to 1.5Pa. Then, the cathode target arc is started to perform multi-arc ion plating with a cathode arc current of 100A. The temperature of multi-arc ion plating is maintained at 400℃ for 60min to obtain a TiAl alloy with a Ti-Al-Cr-Nb-Si-Y high-temperature anti-oxidation coating deposited on the surface.

[0059] Example 6

[0060] This embodiment includes the following steps:

[0061] Step 1: Pre-fabrication of TiAl alloy substrate: The TiAl alloy surface is precision milled and polished using a machining center. Then, it is cleaned until the surface is visually free of dust, oil, water stains, and other impurities, and then washed and dried to obtain the pre-fabricated TiAl alloy substrate. The cleaning process is as follows: first, an industrial degreasing cleaning agent is used for degreasing and cleaning, and then deionized water and ethanol solution are used in sequence for ultrasonic cleaning at 25℃~40℃ for 15 minutes each.

[0062] Step 2, Preparation of Multi-element Alloy Target Material: Prepare Ti 0.3 Al 0.5 Cr 0.1 Nb 0.04 Si 0.05 Y 0.01 A multi-element alloy target is installed on the cathode target position in the vacuum chamber of a multi-arc ion plating equipment;

[0063] Step 3, Substrate Etching: The TiAl alloy substrate prefabricated in Step 1 is placed on the substrate containing Ti in Step 2. 0.3 Al 0.5 Cr 0.1 Nb 0.04 Si 0.05 Y 0.01 On the vacuum chamber support of the multi-alloy target, a vacuum is drawn to ensure that the pressure inside the vacuum chamber does not exceed 5 × 10⁻⁶. -3 Pa, turn on the high-frequency plasma power supply, control the plasma voltage to 500V, then introduce H2 to adjust the pressure in the vacuum chamber to 1Pa, control the vacuum chamber temperature to 400℃, then apply a base bias voltage of 60V to the pre-fabricated TiAl alloy substrate, and the resulting electric field performs plasma etching on the TiAl alloy substrate for 20min to remove surface oxide impurities, then stop introducing H2, introduce Ar gas to adjust the pressure in the vacuum chamber to 1Pa, and use a base bias voltage of 500V to perform plasma etching on the TiAl alloy substrate for 60min;

[0064] Step 4, Multi-element Coating Deposition: An external electric field of -300V is applied to the TiAl alloy etched by Ar plasma in Step 3, and Argon gas is introduced into the vacuum chamber to adjust the vacuum degree to 1.5Pa. Then, the cathode target arc is started to perform multi-arc ion plating. The cathode arc current is 80A, the temperature of multi-arc ion plating is maintained at 400℃, and the time is 80min, to obtain a TiAl alloy with a Ti-Al-Cr-Nb-Si-Y high-temperature anti-oxidation coating deposited on the surface.

[0065] Figure 3 The graphs show the weight changes of TiAl alloys with Ti-Al-Cr-Nb-Si-Y high-temperature anti-oxidation coatings and TiAl alloys without coatings prepared in Examples 5-6 of this invention, obtained by isothermal oxidation over 600 hours. Figure 3As can be seen, compared with the uncoated TiAl alloy, the TiAl alloy with the surface-deposited Ti-Al-Cr-Nb-Si-Y high-temperature anti-oxidation coating prepared in Example 5 has a 76.75% lower weight gain rate, and the TiAl alloy with the surface-deposited Ti-Al-Cr-Nb-Si-Y high-temperature anti-oxidation coating prepared in Example 6 has a 61.88% lower weight gain rate. This indicates that the Ti-Al-Cr-Nb-Si-Y high-temperature anti-oxidation coating prepared in this invention exhibits good high-temperature anti-oxidation performance.

[0066] Figure 4 These are macroscopic photographs of the substrate and the TiAl alloy with a Ti-Al-Cr-Nb-Si-Y high-temperature anti-oxidation coating deposited on its surface, used in Example 6 of this invention, after 600 hours of high-temperature oxidation. Figure (a) represents the TiAl alloy substrate, and Figure (b) represents the TiAl alloy with the Ti-Al-Cr-Nb-Si-Y high-temperature anti-oxidation coating deposited on its surface. Figure 4 It can be seen that the TiAl alloy with a Ti-Al-Cr-Nb-Si-Y high-temperature anti-oxidation coating deposited on the surface turns black after oxidation, but the coating surface is smooth and intact, without any peeling or flaking. In contrast, the TiAl alloy substrate without the coating is yellow, and the sample peels and flaks off severely, indicating that the oxide layer generated during the high-temperature oxidation process has suffered very serious flaking.

[0067] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the inventive essence shall still fall within the protection scope of the present invention.

Claims

1. A method for preparing a high-temperature anti-oxidation coating suitable for TiAl alloys, characterized in that, The method includes the following steps: Step 1: Pre-fabrication of TiAl alloy substrate: After finishing the surface of TiAl alloy, polish it, then clean it until the surface is free of dust, oil, water stains and impurities, and then dry it to obtain the pre-fabricated TiAl alloy substrate. Step 2, Preparation of Multi-element Alloy Target Material: Prepare Ti a Al b Cr c Nb d Si e Y f A multi-element alloy target is installed on the cathode target position in the vacuum chamber of a multi-arc ion plating equipment, where a, b, c, d, e, and f represent the atomic percentages of the corresponding elements, and a+b+c+d+e+f=1, 0.1≤a≤0.3, 0.5≤b≤0.6, 0.1≤c≤0.16, 0.03≤d≤0.04, 0.05≤e≤0.10, and f≈0.

01. Step 3, Substrate Etching: The TiAl alloy substrate prefabricated in Step 1 is placed on the substrate containing Ti in Step 2. a Al b Cr c Nb d Si e Y f On the vacuum chamber support of the multi-alloy target, a vacuum is drawn to ensure that the pressure inside the vacuum chamber does not exceed 5 × 10⁻⁶. - 3 Pa, turn on the high-frequency plasma power supply, then introduce H2 to adjust the pressure in the vacuum chamber to 0.5Pa~2Pa, then apply a bias voltage to the pre-fabricated TiAl alloy substrate, and the resulting electric field performs plasma etching on the TiAl alloy substrate to remove the oxide impurities on the surface. Then stop introducing H2, introduce Ar gas to adjust the pressure in the vacuum chamber to 0.5Pa~2Pa, and continue to perform plasma etching on the TiAl alloy substrate. The high-frequency plasma power supply is turned on to control the plasma voltage at 200V~500V and the vacuum chamber temperature at 200℃~400℃. When H2 is introduced for plasma etching, the substrate bias voltage is set to 40V~60V and the etching time is 10min. When Ar gas is introduced for plasma etching, the substrate bias voltage is set to 200V~600V and the etching time is 30min~60min. Step 4, Multi-element coating deposition: An external electric field is applied to the TiAl alloy after Ar plasma etching in Step 3, and argon gas is introduced into the vacuum chamber to adjust the vacuum level. Then, the cathode target arc is started to perform multi-arc ion plating to obtain a TiAl alloy with a Ti-Al-Cr-Nb-Si-Y high-temperature anti-oxidation coating deposited on the surface.

2. The method for preparing a high-temperature anti-oxidation coating suitable for TiAl alloys according to claim 1, characterized in that, The finishing process described in step one involves precision milling of the TiAl alloy surface using a machining center.

3. The method for preparing a high-temperature anti-oxidation coating suitable for TiAl alloys according to claim 1, characterized in that, The cleaning process described in step one is as follows: first, use an industrial degreasing cleaning agent to remove oil, and then use deionized water and ethanol solution to sonicate for 15 min to 20 min at 25℃ to 40℃ respectively.

4. The method for preparing a high-temperature anti-oxidation coating suitable for TiAl alloys according to claim 1, characterized in that, In step four, the applied external electric field voltage is -100V to -350V, the vacuum degree is adjusted to 0.5Pa to 2Pa, the cathode arc current generated by the cathode target arc is 50A to 120A, the temperature of the multi-arc ion plating is maintained at 150℃ to 400℃, and the time is 20min to 80min.

5. A high-temperature anti-oxidation coating suitable for TiAl alloys, characterized in that, Prepared by the method described in any one of claims 1 to 4.

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