Method for preparing Pt-Hf co-modified single-phase γ′-Ni3Al coating by magnetron sputtering with embedded target and coating

Abstract

This invention discloses a method for preparing a Pt-Hf co-modified single-phase γ′-Ni3Al coating using magnetron sputtering with an embedded target, specifically relating to the field of high-temperature protective coating technology. The method includes the following steps: surface treatment of a high-temperature alloy substrate; electroplating of a platinum layer; vacuum pre-diffusion treatment; deposition of an Al layer containing Hf using a specially designed Al-Hf embedded target via magnetron sputtering; and finally, vacuum diffusion annealing to obtain the Pt-Hf co-modified single-phase γ′-Ni3Al coating. The embedded target consists of uniformly embedded pure Hf cylinders within the rapid consumption zone of a pure Al target surface, precisely controlling the composition of the deposited layer by utilizing the difference in sputtering yield between Al and Hf. The coating prepared by this invention has a single-phase γ′-Ni3Al structure, with no β-phase residue, avoiding large wrinkles caused by phase transformation during coating service, and simultaneously suppressing the formation of needle-like secondary reaction zones (SRZ) on the substrate. The introduction of the active element Hf significantly improves the adhesion of the alumina film. This method significantly reduces the cost of the target material and provides precise composition control, making it suitable for the protection of nickel-based high-temperature alloy turbine blades.

Description

Technical Field

[0001] This invention relates to the field of high-temperature protective coating technology for aero-engines, and in particular to a method for preparing a Pt-Hf co-modified single-phase γ′-Ni3Al coating using a low-cost embedded target. Background Technology

[0002] As aero-engines continue to evolve towards higher thrust-to-weight ratios and higher gas turbine efficiency, the service temperature of turbine blades is constantly increasing, making the preparation of thermal barrier coatings (TBCs) on them an inevitable choice. Among them, β-(Ni,Pt)Al coatings are widely used in the binder layer of thermal barrier coatings due to their advantages such as high melting point, good resistance to high-temperature oxidation, small difference in thermal expansion coefficient with the high-temperature alloy substrate, and wide composition range in the phase diagram. However, in practical applications, β-(Ni,Pt)Al coatings suffer from defects such as severe interdiffusion, easy formation of needle-like SRZs in the substrate near the coating, and surface rumpling caused by volume shrinkage due to the β-to-γ′ phase transformation during service, which seriously affect the service life of thermal barrier coatings.

[0003] To address the aforementioned issues, researchers proposed Pt-modified γ / γ′ and Pt-modified γ′-Ni3Al coatings. These coatings exhibit good chemical compatibility with the substrate, fundamentally inhibiting elemental interdiffusion between the coating and the substrate. Furthermore, the presence of Pt provides excellent resistance to high-temperature oxidation. However, compared to β-(Ni,Pt)Al, the γ′ phase has a lower Al content, resulting in less durable oxidation resistance compared to the β phase. According to the theory of high-temperature oxidation, an appropriate concentration of the active element Hf can effectively reduce the oxidation rate and improve the adhesion of the oxide film. Therefore, modifying the γ′-Ni3Al coating with the active element Hf can compensate for its low Al content and insufficient oxidation resistance. However, the precise addition of Hf to the magnetron sputtering layer currently faces process difficulties and cost issues: (1) If a single Al-Hf alloy target is used for magnetron sputtering. Because Hf has an extremely high melting point and density, and its maximum solubility in Al is only 0.153 at.%, it not only makes the Al-Hf alloy target difficult to melt, but also causes uncontrollable segregation of Hf in the alloy target, making it impossible to accurately control the Hf content in the magnetron sputtering deposition layer. At the same time, the alloy target is expensive to prepare and has a low utilization rate (only ~30%), which will result in a great waste of the precious metal Hf; (2) If a pure Hf target is used for multi-target magnetron sputtering, the magnetron sputtering process will become complicated, and it will be impossible to accurately control the Hf content in the magnetron sputtering layer. In addition, because Hf is very easy to oxidize, the surface of the pure Hf target needs to be ion-etched and cleaned before each sputtering, which results in a large waste of Hf. (3) If Hf powder is added to the electroplating solution during the Ni / Pt layer electroplating process to introduce Hf through composite electroplating, Hf tends to accumulate locally in the coating in the form of particles. This not only fails to exert the modifying effect of the active element Hf, but also causes severe internal oxidation of the coating. Therefore, developing a low-cost, compositionally controllable, and high-performance Pt-Hf co-modified single-phase γ′-Ni3Al coating preparation technology has important industrial application value. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing a Pt-Hf co-modified γ′-Ni3Al coating on the surface of a nickel-based superalloy. This invention utilizes an innovative "embedded target" design to determine the cylindrical surface area of ​​the Hf in the runway region based on the target Hf content in the deposited layer, achieving precise control of the Hf content while significantly reducing magnetron sputtering costs. By controlling the Al layer thickness to 3 μm and employing a vacuum annealing process, a Pt-Hf co-modified single-phase γ′-Ni3Al coating with low interdiffusion and excellent high-temperature oxidation resistance is obtained. After long-term high-temperature service, no needle-like secondary reaction zones form in the substrate near the coating side.

[0005] The technical solution adopted in this invention is as follows: A method for preparing a Pt-Hf co-modified single-phase γ′-Ni3Al coating using magnetron sputtering with an embedded target, for use in preparing a bonding layer for engine turbine blades, includes the following steps: (1) Electroplating a Pt layer on the surface of a high-temperature alloy substrate: The thickness of the electroplated Pt layer is 2~7 μm (preferably 3~6 μm, more preferably 4~5 μm). In this step, the Pt plating layer must be of uniform thickness in all locations on the substrate and free from any visible peeling, cracking, or flaking.

[0006] (2) Pre-diffusion treatment: The sample after electroplating the Pt layer is placed in a vacuum with a degree of less than 1×10 −3 Pa (preferably equal to or less than 1 × 10) −4 Pa, more preferably equal to or less than 1 × 10 −5 In a vacuum annealing furnace (Pa), the temperature is maintained at 1000~1100 °C (preferably 1020~1080 °C, more preferably 1050~1060 °C) for 2~4 hours (preferably 3~4 h, more preferably 3.5~4 h).

[0007] (3) Magnetron sputtering of Hf-containing aluminum layer: Using magnetron sputtering technology, an Hf-containing aluminum layer with a thickness of 2.5~3.5 μm is deposited on the sample surface using an Al-Hf embedded target. The Al-Hf embedded target used for sputtering uses Al with a purity >99.95 wt.% as the substrate, and Hf pillars and / or sheets with a purity >99.95 wt.% are uniformly embedded in the rapid consumption zone (i.e., the runway zone) on the target surface. The number of Hf pillars and / or sheets depends on the target Hf content R required in the magnetron sputtered deposited layer and the area of ​​the Hf pillars or sheets exposed on the Al substrate surface. To ensure uniform distribution, the number of Hf pillars and / or sheets can be more than 8 (preferably 8-60, more preferably 10-20). The target Hf content R in the magnetron sputtered deposited layer ranges from 1 to 10 at.% (preferably 1-5 at.%). The area of ​​Hf pillars and / or sheets exposed on the Al substrate surface is 1.52% to 18.34% of the runway area (preferably 1.55% to 11%, more preferably 1.55% to 7%).

[0008] In this step, the purpose of magnetron sputtering a 2.5–3.5 μm Hf-containing aluminum layer is to limit the total Al source, forcing the magnetron sputtered deposit to form a single γ′-Ni3Al phase after sufficient annealing. If the sputtered Al layer thickness is <2.5 μm, the final coating will be a γ / γ′ dual-phase coating with low Al content and insufficient oxidation resistance. If the sputtered Al layer thickness is >3.5 μm, other Al-rich phases (such as Ni5Al3 or NiAl phase) will appear in the final coating, which will also be detrimental to the coating performance.

[0009] (4) Diffusion annealing treatment: The sample after magnetron sputtering deposition is placed in a vacuum furnace, and the vacuum level should be equal to or lower than 1×10⁻⁶. -3 Pa (preferably equal to or less than 1 × 10) −4 Pa, more preferably equal to or less than 1 × 10 −5 The magnetron sputtered layer is heated at 1050~1150 ℃ (preferably 1080~1120 ℃, more preferably 1100~1110 ℃) for 8~16 hours (preferably 10~14 hours, more preferably 11~12 hours) to allow the magnetron sputtered layer to fully diffuse with the matrix elements, thereby obtaining a Pt-Hf co-modified single-phase γ′-Ni3Al coating.

[0010] In this step, a high vacuum level is required to prevent oxidation of the coating during annealing, which would affect the final coating quality. A longer annealing time is set for two reasons: firstly, to allow Al atoms in the sputtered layer to diffuse sufficiently downwards, avoiding the formation of harmful Al-rich Ni5Al3 phases on top of the prepared coating; and secondly, because Hf atoms have a large atomic radius, a longer annealing time prevents Hf from accumulating on the top layer of the coating.

[0011] The method for preparing a Pt-Hf co-modified single-phase γ′-Ni3Al coating by magnetron sputtering with an embedded target, wherein step (1) involves electroplating a Pt layer on the surface of a high-temperature alloy substrate, including: (1) Surface treatment: The high-temperature alloy substrate sample is ground, sandblasted and cleaned.

[0012] (2) Electroplating Pt layer: A metal Pt layer with a thickness of 2~7 μm is electroplated on the surface of the treated substrate by alkaline Pt plating process; wherein the alkaline Pt plating solution is prepared by the main salt Pt(NH3)2(NO)2 and the auxiliary salt NaNO2, and the pH is adjusted to 11~13 by ammonia water with a mass concentration of 20~28%; the concentration of the main salt in the solution is 2~6 g / L, and the concentration of the auxiliary salt in the solution is 2~6 g / L.

[0013] The selected high-temperature alloy was a nickel-based high-temperature alloy. The entire electroplating process was carried out in a constant-temperature water bath at 70~80 ℃, with a current density of 15~25 mA / cm². 2 The Pt layer deposition rate is approximately 0.05~0.1 μm / min.

[0014] The method for preparing Pt-Hf co-modified single-phase γ′-Ni3Al coating by magnetron sputtering with embedded target material, in step (3), the design method of Al-Hf embedded target material is as follows: first, based on the surface morphology of the target material after magnetron sputtering, the rapid consumption area of ​​the target material surface, i.e., the runway area, is determined; second, several blind holes are uniformly processed in the runway area, and pure Hf cylindrical interference fit is embedded in the holes.

[0015] In the method for preparing Pt-Hf co-modified single-phase γ′-Ni3Al coating by magnetron sputtering with an embedded target, step (3) involves an embedded target composed of a pure Al target with machined cylindrical blind holes or through holes and pure Hf pillars or sheets embedded in the blind holes or through holes. The theoretical surface area S occupied by the Hf cylinder in the runway area is... Hf The total surface area S of pure Al within the runway area Al The ratio is based on the expected atomic ratio R of Hf to Al in the deposited layer and the sputtering yield ratio (Y) of the two under argon sputtering. Al / Y Hf It is determined that the following relation is satisfied: S Hf / S Al ≈ R×(Y) Al / Y Hf Based on the data and experimental test results, the final output ratio (Y) was determined. Al / Y Hf The range is 1.5~2; In the method for preparing Pt-Hf co-modified single-phase γ′-Ni3Al coating by magnetron sputtering with embedded target material, in step (3), the actual surface area of ​​the Hf cylinder in the runway area is slightly larger than its theoretical surface area, and the increment is 3~10%; the increment is used to compensate for the low Hf content in the deposition layer caused by a small amount of Al sputtering in the non-runway area during the magnetron sputtering process.

[0016] In the method for preparing Pt-Hf co-modified single-phase γ′-Ni3Al coating by magnetron sputtering with an embedded target, in step (3), the working gas for magnetron sputtering is argon (Ar), the sputtering pressure is 0.1~0.8 Pa, the sputtering power is 1~3 kW, the sputtering voltage is 400~600 V, and the substrate temperature is 150~250 ℃.

[0017] In the method for preparing Pt-Hf co-modified single-phase γ′-Ni3Al coating by magnetron sputtering with embedded target material, in step (4), the vacuum degree, temperature and holding time of diffusion annealing must be strictly controlled; by precisely controlling the thickness of the magnetron sputtered deposition layer (2.5~3.5 μm) and the vacuum annealing time (8~12 h), a single-phase L12 structure γ′-Ni3Al coating with a thickness of 25~35 μm can be obtained, which does not contain other Ni-Al phases; The coating has the advantages of low interdiffusion, low wrinkling, high strength and toughness and excellent resistance to high temperature oxidation. Moreover, after long-term service, no needle-like topologically packed (TCP) phases precipitate at the interface between the coating and the substrate.

[0018] The method for preparing a Pt-Hf co-modified single-phase γ′-Ni3Al coating by magnetron sputtering with an embedded target is characterized in that the Hf content in the magnetron sputtered deposition layer ranges from 1 to 10 at.%; after diffusion annealing, the prepared coating contains 5 to 15 at.%, 19 to 27 at.%, 0.1 to 1.0 at.%, and the balance is Ni and matrix alloying elements.

[0019] The design concept of this invention is: This invention develops a coating exhibiting low interdiffusion, low wrinkling, and high strength and toughness—a "two-low-one-high" characteristic—for long-term high-temperature service. Traditional β-(Ni,Pt)Al coatings are widely used as binder materials in thermal barrier coatings due to their high melting point, excellent high-temperature oxidation resistance, and good thermal compatibility with the substrate. However, after long-term service, severe interdiffusion often occurs between the coating and the substrate. To address this issue, it is necessary to reduce the Al content of the coating while ensuring excellent long-term high-temperature oxidation resistance. Therefore, we propose a Pt-Hf co-modified single-phase γ′-Ni3Al coating. This coating has a chemical composition close to that of the substrate, and utilizes the excellent modifying effects of Pt and Hf to compensate for the insufficient Al content in the γ′-Ni3Al coating. Currently, introducing Hf into the coating using traditional processes is not only difficult to precisely control the Hf content but also faces high costs. Therefore, we designed a composite embedded target material with Hf cylinders embedded in the runway region of a pure aluminum target, introducing Hf through magnetron sputtering. Based on the sputtering yield ratio of Hf and Al atoms, the area occupied by the Hf cylinders in the runway region is calculated, allowing for precise control of the Hf content in the magnetron sputtering deposited layer. This invention, through an innovative "embedded target" design, saves on target material costs while precisely controlling the Hf content in the deposited layer. The resulting Pt-Hf co-modified single-phase γ′-Ni3Al coating exhibits excellent high-temperature oxidation resistance and does not undergo severe interdiffusion with the high-temperature alloy matrix.

[0020] The present invention has the following advantages and beneficial effects: 1. Precise and controllable Hf content: Based on the expected atomic ratio R of Hf to Al in the deposited layer and the sputtering yield ratio (Y) of the two under argon sputtering. Al / Y Hf The area occupied by the Hf cylinder in the rapid consumption zone of magnetron sputtering can be determined, and the Hf content in the magnetron sputtering deposition layer can be precisely controlled without changing the magnetron sputtering process parameters.

[0021] 2. Significantly reduced costs: Compared to preparing a whole aluminum alloy target containing Hf, this invention only requires embedding a small number of Hf cylinders in the runway area of ​​a regular pure aluminum target, which greatly improves the material utilization rate and effectively reduces the cost of target preparation.

[0022] 3. High structural stability: The prepared coating is a single-phase γ′, and there is no β to γ′ phase transition during service, which fundamentally alleviates the coating wrinkling phenomenon; moreover, the coating has a low Al content, which avoids the formation of needle-like SRZ in the substrate near the coating due to severe interdiffusion, thus maintaining the high-temperature mechanical properties of the substrate.

[0023] 4. Excellent antioxidant properties: The 30 μm coating thickness provides ample Al reserves, and the modification effect of active element Hf and noble metal element Pt makes the coating have excellent long-term antioxidant capacity at 1100 ℃. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of the "Al-Hf inlaid target" used in the embodiments of the present invention.

[0025] Figure 2 The figures show the cross-sectional morphology (a) of the Hf-doped aluminum layer deposited after magnetron sputtering in Example 1, the cross-sectional morphology (b) of the Pt-Hf co-modified γ′-Ni3Al coating prepared after diffusion annealing, and the corresponding XRD patterns (c). In figure (c), the horizontal axis 2theta represents the diffraction angle (deg.), and the vertical axis Relative intensity represents the relative intensity.

[0026] Figure 3 The cross-sectional morphology (a) of the Hf-doped aluminum layer deposited after magnetron sputtering in Example 2, the cross-sectional morphology (b) of the Pt-Hf co-modified γ′-Ni3Al coating prepared after diffusion annealing, and the corresponding XRD patterns (c) are shown.

[0027] Figure 4 The cross-sectional morphology of the Pt-Hf co-modified coating (a) prepared in Example 2 and the conventional β-(Ni, Pt)Al coating (b) after 500 cycles of cyclic oxidation at 1100 °C is shown. Each cycle includes 50 min of heat treatment followed by 10 min of air cooling.

[0028] Figure 5 The cross-sectional morphology (a) and XRD pattern (b) of the high Pt content Pt-Hf co-modified γ′-Ni3Al coating prepared in Example 3 are shown.

[0029] Figure 6 The cross-sectional morphology of the deposited layer after magnetron sputtering of Al-Hf alloy target is shown in Comparative Example 1. Detailed Implementation

[0030] The present invention will be further described in detail below with reference to specific embodiments and comparative examples. It should be noted that the following embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.

[0031] Example 1

[0032] This embodiment aims to demonstrate how to design a target material using sputtering yield differences and prepare a single-phase coating with Hf content meeting the requirements.

[0033] 1. Experimental Materials and Surface Treatment (1) Matrix material: Second-generation single crystal is selected Nickel-based High-temperature alloy N5 is produced by cutting high-temperature alloy bars into small circular pieces with a height of Φ16×2mm using wire cutting equipment, and cutting a small circular hole of Φ1.6 mm at the edge of each circular piece to facilitate the suspension of samples for electroplating and cyclic oxidation testing.

[0034] (2) Surface treatment: The cut small round pieces were polished with 240# and 400# sandpaper in sequence, and then the polished small round pieces were water-blasted (220# white corundum sand, air pressure 0.3 MPa) until the surface showed a uniform matte metallic luster. Then the small round pieces were placed in a mixture of deionized water and ethanol acetone (volume ratio 1:1) for ultrasonic cleaning for 20 minutes, and then blown dry.

[0035] 2. Design and fabrication of magnetron sputtering targets In this embodiment, the objective is to obtain a deposition layer with an Al / Hf atomic ratio of approximately 95:5 (i.e., an Hf content of 5 at.%) via magnetron sputtering. The sputtering voltage in this embodiment is 560V, and the working gas is Ar. Based on the NPL database and previous process exploration, we determined that the sputtering yield Y of Al is... Al ≈1.2 (atoms / ion); Sputtering yield Y of Hf Hf ≈0.6 (atoms / ions), that is, the sputtering yield ratio Y of Al and Hf atoms. Al / Y Hf = 2. Schematic diagram of magnetron sputtering target as shown below Figure 1 As shown, the overall dimensions are 382 mm in length, 128 mm in width, and 8 mm in thickness.

[0036] The surface morphology of the 8 (or more than 2) targets consumed in the early stage of magnetron sputtering in the laboratory was analyzed. The magnetron sputtering process parameters in the early stage were consistent with those in step 3. Coating preparation process of this embodiment (3) magnetron sputtering containing Hf aluminum layer. The difference was that the pure Al target used in the early stage was selected as the substrate material and the second-generation single crystal was selected. Nickel-basedHigh-temperature alloy N5 was used to determine the location and size of the racetrack region on the surface of each target material. The racetrack region (also known as the "etched racetrack" or "racetrack") is characterized by uneven magnetic field distribution on the target surface due to the specific arrangement of magnets behind the target in magnetron sputtering. In areas where the magnetic field is parallel to the target surface, electrons are strongly confined, forming a high-density plasma ring region. This results in preferential and rapid sputtering etching of the target material in this area, gradually forming a groove that resembles a racetrack. All racetrack regions were found to be approximately 20696 mm². 2 .

[0037] During the target material processing, the theoretical surface area S occupied by the Hf cylinder in the runway area Hf The total surface area S of pure Al within the runway area Al The ratio is based on the expected atomic ratio R of Hf to Al in the deposited layer and the sputtering yield ratio (Y) of the two under argon sputtering. Al / Y Hf It is determined that the following relation is satisfied: S Hf / S Al ≈ R×(Y) Al / Y Hf Under the magnetron sputtering process parameters in this embodiment, Y Al / Y Hf =2, substituting this into the above relationship, we can obtain the theoretically required surface area S of the Hf cylinder in the runway area. Hf 1881 mm 2 To this end, we uniformly machined 16 blind holes with a diameter of 12.5 mm and a height of 5 mm in the runway area of ​​a pure Al target (purity > 99.95 wt.%), and embedded pure Hf cylinders of the same size (diameter and height) (purity > 99.95 wt.%) in each blind hole. Therefore, the total surface area of ​​the Hf cylinders is 1962.5 mm². 2 The actual Hf surface area of ​​the target is slightly higher than the theoretical Hf surface area. This can compensate for the lower Hf content in the deposited layer caused by the small amount of Al sputtering in the non-runway region during magnetron sputtering.

[0038] 3. Coating preparation process (1) Pt plating: The surface-treated substrate sample was suspended in an alkaline Pt plating solution to electroplate a 4 μm Pt layer. The alkaline Pt plating solution was prepared by using Pt(NH3)2(NO)2 as the main salt and NaNO2 as the auxiliary salt. First, the two were mixed at a mass ratio of 1:1 and placed in deionized water and boiled to form a platinum salt plating solution. The concentration of Pt(NH3)2(NO)2 in the plating solution was 5 g / L. Then, the pH of the salt solution was adjusted to 11 using ammonia solution with a mass concentration of 26-28%. Finally, the solution was placed in an 80 ℃ constant-temperature water bath for electroplating, with a current density set to 20 mA / cm². 2 The Pt layer deposition rate is approximately 0.1 μm / min.

[0039] (2) Pre-diffusion annealing: The sample after Pt electroplating is placed in a vacuum of 1×10 −3 In a vacuum annealing furnace, it was held at 1050°C for 4 hours.

[0040] (3) Magnetron sputtering of Hf-containing aluminum layer: The self-made embedded target described above was used. The working gas for magnetron sputtering was argon (Ar), the sputtering power was 2 kW, the sputtering voltage was 560 V, and the gas pressure was 0.5 Pa. Under these parameters, the deposition rate was approximately 0.05 μm / min, the deposition time was set to 60 min, and the sputtered layer thickness was strictly controlled to 3 μm. The cross-sectional morphology of the Hf-containing aluminum layer after magnetron sputtering is as follows. Figure 2 As shown in (a).

[0041] (4) Diffusion annealing treatment: The magnetron sputtered sample is placed in a vacuum furnace, and the vacuum degree is controlled at 4-5×10. - 4 Pa was heated at 1100 ℃ for 12 h to allow sufficient interdiffusion of elements between the magnetron sputtered layer and the substrate, thus obtaining a Pt-Hf co-modified single-phase γ′-Ni3Al coating.

[0042] 4. Detection of coating microstructure and phase composition Figure 2 (a) shows the cross-sectional morphology of the magnetron sputtered deposit. The figure shows that the Hf-containing aluminum layer thickness is 3.0 μm, consistent with the target thickness. Furthermore, under high-magnification scanning electron microscopy, no visible white particles are present in the cross-sectional morphology of the deposit, indicating that Hf is uniformly distributed in the deposit in the form of solid solution or nanoparticles. The corresponding EDS results show that the Hf contents in deposit regions 1-3 are 5.40 at.%, 4.86 at.%, and 5.27 at.%, respectively, highly consistent with the design target (5 at.%). Figure 2As shown in (b), the thickness of the Pt-Hf co-modified γ′-Ni3Al coating prepared in this example is 25.4 μm. Figure 2 The XRD pattern in (c) shows that the coating is a single γ′-Ni3Al phase and does not contain other Ni-Al phases. This proves the feasibility of the present invention and also shows that the Hf mosaic area calculation formula proposed in the present invention based on the Al and Hf atom sputtering yield ratio is reliable.

[0043] Example 2 This embodiment aims to illustrate that the formula for calculating the surface area of ​​the small Hf cylinder in the embedded target design proposed in this invention is still applicable to low Hf doping content. It also serves to demonstrate that the Pt-Hf co-modified γ′-Ni3Al coating exhibits superior anti-wrinkle performance compared to the traditional β-(Ni,Pt)Al coating.

[0044] 1. Experimental Materials and Surface Treatment The process and conditions were the same as those for the experimental materials and surface treatment in Example 1.

[0045] 2. Design and fabrication of magnetron sputtering targets The process and conditions are the same as those in Example 1 for magnetron sputtering target design and processing. The difference lies in the objective: to obtain a magnetron sputtering deposition layer with an Hf / Al atomic ratio of approximately 1.5:98.5 (i.e., an Hf content of 1.5 at.%), ultimately producing a low-Hf-content Pt-Hf co-modified γ′-Ni3Al coating. Since the target size and the area of ​​the rapid consumption region remain unchanged, only the surface area of ​​the Hf cylinder needs to be changed. The area of ​​the runway region is approximately 20696 mm². 2 Al and Hf sputtering yields compared to Y Al / Y Hf =2, according to the formula proposed in this invention: S Hf / S Al ≈ R×(Y Al / Y Hf Theoretically, the surface area of ​​Hf in the runway area is 531 mm. 2 To this end, we uniformly embedded six Hf cylinders (purity >99.95 wt.%), each 11 mm in diameter and 5 mm in height, in the raceway area of ​​a pure Al target (purity >99.95 wt.%). The total surface area of ​​the Hf cylinders was 569.9 mm². 2 Similarly, the actual Hf surface area of ​​the target is slightly higher than the theoretical Hf surface area in order to compensate for the lower Hf content in the deposited layer caused by the small amount of Al sputtering in the non-runway region during magnetron sputtering.

[0046] 3. Coating preparation process The process and conditions are the same as the coating preparation process in Example 1. The only difference is that the target used in the magnetron sputtering process is the low Hf content embedded target designed in step 2 (S in the runway area). Hf =569.9 mm 2 The cross-sectional morphology of the Hf-containing aluminum layer after magnetron sputtering is as follows: Figure 3 As shown in (a), the cross-sectional morphology of the Pt-Hf co-modified single-phase γ′-Ni3Al coating after diffusion annealing is as follows: Figure 3 As shown in (b).

[0047] 4. Detection of coating microstructure and phase composition EDS energy dispersive spectroscopy results show that Figure 3 In (a), the Hf contents in regions 4-6 of the magnetron sputtered deposition layer are 1.68 at.%, 1.54 at.%, and 1.42 at.%, respectively, with relative deviations from the target Hf content of 1.5 at.% ranging from -5.3% to 12.0%, which is within a reasonable error range. No bright Hf-rich particles were observed in the deposition layer, indicating that Hf is uniformly distributed in the deposition layer in the form of solid solution or nanoparticles. Figure 3 As shown in (b), the thickness of the Pt-Hf co-modified γ′-Ni3Al coating prepared in this example is 25.1 μm. Figure 3 The XRD pattern in (c) shows that the coating is a single γ′-Ni3Al phase, without any other Ni-Al phases. This indicates that the formula for calculating the required area of ​​the Hf cylinder in the raceway region in the embedded target design proposed in this invention is still applicable to low-content Hf doping.

[0048] Figure 4 The cross-sectional morphology of the Pt-Hf co-modified γ′-Ni3Al coating and the conventional β-(Ni,Pt)Al coating after 500 cycles of cyclic oxidation at 1100 °C is shown. After 500 cycles of cyclic oxidation, no crack initiation occurred in the oxide film of the Pt-Hf co-modified γ′-Ni3Al coating, indicating that the coating has excellent resistance to oxide film wrinkling. In addition, compared with the β-(Ni,Pt)Al coating oxide film, the Pt-Hf co-modified γ′-Ni3Al coating oxide film thickens more slowly, which delays coating degradation. Notably, the matrix near the β-(Ni,Pt)Al coating exhibits SRZ due to the formation of needle-like TCP phase, which severely affects the mechanical properties of the high-temperature alloy matrix; while the matrix near the Pt-Hf co-modified γ′-Ni3Al coating does not form SRZ, effectively maintaining the mechanical properties of the high-temperature alloy matrix.

[0049] Example 3 This embodiment aims to illustrate that the Pt-Hf co-modified single-phase γ′-Ni3Al coating prepared according to the present invention maintains a stable phase composition of single-phase γ′-Ni3Al when the Pt content is changed.

[0050] 1. Experimental Materials and Surface Treatment The process and conditions were the same as those for the experimental materials and surface treatment in Example 1.

[0051] 2. Design and fabrication of magnetron sputtering targets The process and conditions are the same as those for the magnetron sputtering target in Example 2.

[0052] 3. Coating preparation process The process and conditions are the same as those in Example 1 for coating preparation. The difference is that during the Pt electroplating process, the Pt layer thickness is set to 6 μm by controlling the electroplating time.

[0053] 4. Detection of coating microstructure and phase composition like Figure 5 As shown in (a), the thickness of the Pt-Hf co-modified γ′-Ni3Al coating with high Pt content prepared in this example is 27.7 μm. Figure 5 (b) is the XRD pattern of the coating, which shows that the coating is still a single γ′-Ni3Al phase. This is different from the XRD patterns in Examples 1 and 2. Figure 2 (c) and Figure 3 Compared to (c), Figure 5 (b) shows a leftward shift of the γ′-Ni3Al diffraction peak, indicating that the increased Pt content in the γ′-Ni3Al phase causes lattice expansion of Ni3Al and a smaller diffraction angle, but the coating remains a single γ′-Ni3Al phase. This demonstrates that the Pt-Hf co-modified single-phase γ′-Ni3Al coating preparation method proposed in this invention ensures that the coating phase composition is a single γ′-Ni3Al phase while the Pt and Hf contents are controllable.

[0054] Comparative Example 1: The target Hf content of this comparative example is the same as that of Example 2, which is 1.5 at.%. This is intended to illustrate the problem that when using a traditional Al-Hf alloy target to prepare a Pt-Hf co-modified γ′-Ni3Al coating by magnetron sputtering, the extremely low solid solubility of Hf in Al leads to target component segregation, which in turn makes it impossible to accurately control the Hf content in the deposited layer.

[0055] 1. Experimental Materials and Surface Treatment The process and conditions were the same as those for the experimental materials and surface treatment in Example 1.

[0056] 2. Design and fabrication of magnetron sputtering targets Al-Hf alloy targets were prepared using a vacuum melting method, with a target Hf content of 1.5 at.%. However, since the maximum solid solubility of Hf in Al is only 0.153 at.%, far lower than the target doping amount, severe Hf segregation occurred during alloy solidification, forming coarse Hf-rich intermetallic compound second phases, making it impossible to obtain a homogeneous Al-Hf alloy. The above alloy was processed into a plate-shaped target with a length of 382 mm, a width of 128 mm, and a thickness of 8 mm for magnetron sputtering.

[0057] 3. Coating preparation process (1) Electroplating Pt: Same as step 3 in Example 1. Coating preparation process (1) Electroplating Pt process and conditions: A 4 μm Pt layer is electroplated on the surface of the surface-treated N5 single crystal high-temperature alloy substrate.

[0058] (2) Pre-diffusion annealing: Same as step 3 in Example 1. Coating preparation process (2) Pre-diffusion annealing process and conditions: The sample after electroplating Pt was kept at 1100 ℃ in vacuum for 4 hours.

[0059] (3) Magnetron sputtering of Hf-containing aluminum layer: Magnetron sputtering was performed using the self-made Al-Hf alloy target described above. The sputtering process parameters were the same as in step 3 of Example 1. Coating preparation process (3) Magnetron sputtering of Hf-containing aluminum layer process and conditions: sputtering power 2 kW, voltage 560 V, gas pressure 0.5 Pa, deposition time 60 min, target deposition layer thickness 3 μm. The difference is that the magnetron sputtering target used in this comparative example is the self-made Al-Hf alloy target described above.

[0060] (4) Diffusion annealing treatment: Same as step 3 in Example 1. Coating preparation process 4) Diffusion annealing treatment process and conditions: The sample after magnetron sputtering was kept at 1100 °C in vacuum for 12 hours to obtain Pt-Hf co-modified γ′-Ni3Al coating.

[0061] 4. Microstructure and composition analysis of the coating The cross-sectional morphology of the magnetron sputtered deposit is as follows Figure 6 As shown. The corresponding EDS results show that the Hf content in deposition layer regions 7-9 is 0.60 at.%, 0.74 at.%, and 0.67 at.%, respectively, which significantly deviates from the target value of 1.5 at.% designed during alloy target smelting. This is due to severe Hf segregation in the alloy target: the Hf-rich region has a high Hf melting point and low sputtering yield (γ). Hf ≈ 0.6), its actual sputtering contribution was far lower than expected; while in the Hf-depleted region, although the sputtering yield was high, the Hf source supply was insufficient, and the combined effect of the two resulted in the Hf content of the sedimentary layer being far lower than the design value. Local areas of the sedimentary layer in Example 2 and Comparative Example 1 (see...) Figure 3(a) Areas 4-6; Figure 6 Table 1 shows the EDS results for regions 7-9 and their deviations from the target Hf content. The table shows that the relative deviation of Hf in the deposited layer corresponding to the Al-Hf inlaid target is only -5.3% to 12.0%, while the relative deviation of Hf in the deposited layer corresponding to the alloy target is as high as -60% to -55.3%, indicating a severely low Hf content.

[0062] Table 1 shows the EDS results of the deposition layers in Example 2 and Comparative Example 1.

[0063] The experimental results above demonstrate that the method proposed in this invention for preparing Pt-Hf co-modified single-phase γ′-Ni3Al coatings using embedded target magnetron sputtering can effectively reduce target costs while precisely controlling the Hf content of the coating. The Pt-Hf co-modified single-phase γ′-Ni3Al coating exhibits low interdiffusion with the high-temperature alloy substrate and excellent resistance to long-term high-temperature oxidation. Therefore, it can be used as a novel thermal barrier coating binder material for high-temperature protection of aero-engine turbine blades.

[0064] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made in accordance with the spirit and essence of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a Pt-Hf co-modified single-phase γ′-Ni3Al coating by magnetron sputtering with an embedded target, characterized in that, Includes the following steps: (1) Electroplating a Pt layer on the surface of a high-temperature alloy substrate: The thickness of the electroplated Pt layer is 2~7 μm (preferably 3~6 μm, more preferably 4~5 μm). (2) Pre-diffusion treatment: The sample after electroplating the Pt layer is placed in a vacuum with a degree of less than 1×10 −3 Pa (preferably equal to or less than 1 × 10) −4 Pa, more preferably equal to or less than 1 × 10 −5 In a vacuum annealing furnace (Pa), the temperature is maintained at 1000~1100 ℃ (preferably 1020~1080 ℃, more preferably 1050~1060 ℃) for 2~4 hours (preferably 3~4 h, more preferably 3.5~4 h). (3) Magnetron sputtering of Hf-containing aluminum layer: Using magnetron sputtering technology, an Hf-containing aluminum layer with a thickness of 2.5~3.5 μm is deposited on the sample surface using an Al-Hf embedded target. The Al-Hf embedded target used for sputtering uses Al with a purity >99.95 wt.% as the substrate, and Hf pillars and / or sheets with a purity >99.95 wt.% are uniformly embedded in the rapid consumption zone (i.e., the runway zone) on the target surface. The number of Hf pillars and / or sheets depends on the target Hf content R required in the magnetron sputtered deposited layer and the area of ​​the Hf pillars or sheets exposed on the Al substrate surface. To ensure uniform distribution, the number of Hf pillars and / or sheets can be more than 8 (preferably 8-60, more preferably 10-20). The target Hf content R in the magnetron sputtered deposited layer ranges from 1 to 10 at.% (preferably 1-5 at.%). The area of ​​Hf pillars and / or sheets exposed on the Al substrate surface is 1.52% to 18.34% of the runway area (preferably 1.55% to 11%, more preferably 1.55% to 7%). (4) Diffusion annealing treatment: The sample after magnetron sputtering deposition is placed in a vacuum furnace, and the vacuum level should be equal to or lower than 1×10⁻⁶. -3 Pa (preferably equal to or less than 1 × 10) −4 Pa, more preferably equal to or less than 1 × 10 −5 The magnetron sputtered layer is heated at 1050~1150 ℃ (preferably 1080~1120 ℃, more preferably 1100~1110 ℃) for 8~16 hours (preferably 10~14 hours, more preferably 11~12 hours) to allow the magnetron sputtered layer to fully diffuse with the matrix elements, thereby obtaining a Pt-Hf co-modified single-phase γ′-Ni3Al coating.

2. The method according to claim 1, characterized in that: The process of electroplating a Pt layer on the surface of a high-temperature alloy substrate includes: (1) Surface treatment: The high-temperature alloy substrate sample is ground, sandblasted and cleaned; (2) Electroplating Pt layer: A metal Pt layer with a thickness of 2~7 μm is electroplated on the surface of the treated substrate by an alkaline Pt plating process; wherein the alkaline Pt plating solution is prepared by the main salt Pt(NH3)2(NO)2 and the auxiliary salt NaNO2, and the pH is adjusted to 11~13 by ammonia water with a mass concentration of 20~28%; the concentration of the main salt in the solution is 2~6 g / L, and the concentration of the auxiliary salt in the solution is 2~6 g / L; The entire electroplating process is carried out in a constant temperature water bath at 70~80 ℃, with a current density of 15~25 mA / cm². 2 The Pt layer deposition rate is approximately 0.05~0.1 μm / min.

3. The method according to claim 1, characterized in that: In step (3), the design method of Al-Hf inlay target is as follows: First, based on the surface morphology of the target after magnetron sputtering, the rapid consumption area of ​​the target surface, namely the runway area, is determined; second, several blind holes are uniformly processed in the runway area, and pure Hf cylindrical interference fit is embedded in the holes.

4. The method according to claim 1 or 3, characterized in that, In step (3), the inlaid target material is composed of a pure Al target material with machined cylindrical blind holes or through holes and pure Hf pillars or sheets embedded in the blind holes or through holes, wherein the theoretical surface area S occupied by the Hf cylinder in the runway area is S. Hf The total surface area S of pure Al within the runway area Al The ratio is based on the expected atomic ratio R of Hf to Al in the deposited layer and the sputtering yield ratio (Y) of the two under argon sputtering. Al / Y Hf It is determined that the relation S satisfies the following expression: Hf / S Al ≈ R×(Y) Al / Y Hf Based on the data and experimental test results, the final output ratio (Y) was determined. Al / Y Hf The range is 1.5~2; In step (3), during the processing of the inlaid target, the actual surface area of ​​the Hf cylinder in the runway area is slightly larger than its theoretical surface area, and the increment is 3~10%; the increment is used to compensate for the low Hf content in the deposition layer caused by a small amount of Al sputtering in the non-runway area during the magnetron sputtering process.

5. The method according to claim 1, characterized in that, In step (3), the working gas for magnetron sputtering is argon (Ar), the sputtering pressure is 0.1~0.8 Pa, the sputtering power is 1~3 kW, the sputtering voltage is 400~600 V, and the substrate temperature is 150~250 ℃.

6. The method according to claim 1, characterized in that, In step (4), the vacuum degree, temperature and holding time of diffusion annealing must be strictly controlled; by precisely controlling the thickness of the magnetron sputtering deposited layer (2.5~3.5 μm) and the vacuum annealing time (8~12 h), a single-phase L12 structure γ′-Ni3Al coating with a thickness of 25~35 μm can be obtained, which does not contain other Ni-Al phases; The coating has the advantages of low interdiffusion, low wrinkling, high strength and toughness and excellent resistance to high temperature oxidation. Moreover, after long-term service, no needle-like topologically packed (TCP) phases precipitate at the interface between the coating and the substrate.

7. The method according to claim 1, characterized in that: The high-temperature alloy matrix is ​​a nickel-based high-temperature alloy.

8. A Pt-Hf co-modified single-phase γ′-Ni3Al coating prepared by the method according to any one of claims 1-6, characterized in that, The Hf content in the magnetron sputtered deposited layer ranges from 1 to 10 at.%; after diffusion annealing, the prepared coating contains 5 to 15 at.%, 19 to 27 at.%, 0.1 to 1.0 at.%, and the balance is Ni and matrix alloying elements.

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