Tantalum-tungsten alloy anti-oxidation coating and its preparation process

Abstract

This application relates to the technical field of anti-oxidation coatings, specifically disclosing a tantalum-tungsten alloy anti-oxidation coating and its preparation process. The tantalum-tungsten alloy anti-oxidation coating comprises a sequentially stacked transition layer, an inner layer, a barrier layer, and an outer layer. The transition layer is prepared by co-sputtering an Ir target, a Ta target, and a Re target. The inner layer is prepared by parts by weight of Si, MoSi2, Y, and Ta-W alloy powder. The barrier layer is prepared by parts by weight of Al2O3, Yb2O3, and 3YZrO2. The outer layer is prepared by parts by weight of a composite of Yb2O3, La2O3, Gd2O3, SiC, and B4C; and a polynary boride of ZrB2 and HfB2. The tantalum-tungsten alloy anti-oxidation coating prepared in this application exhibits excellent high-temperature oxidation resistance.

Description

Technical Field

[0001] The present application relates to the technical field of anti-oxidation coatings, and more specifically, to a tantalum-tungsten alloy anti-oxidation coating and a preparation process thereof. Background Art

[0002] Faced with the dual challenges of high temperature and harsh environment, tantalum-tungsten alloy has become the main structural material for key high-temperature components in aerospace due to its high melting point, high thermal strength, wear resistance and creep resistance. However, this alloy is prone to oxidation in high-temperature working environments, causing its performance to gradually decline, which restricts its practical application.

[0003] Currently, there are two main approaches to improving the oxidation resistance of tantalum and tantalum alloys: alloying and coating. While alloying can improve the substrate's oxidation resistance to a certain extent, adding excessive alloying elements can reduce the substrate's mechanical properties. Furthermore, the degree of alloying is limited and cannot fully meet application requirements. Anti-oxidation coating, on the other hand, effectively improves the substrate's oxidation resistance without compromising its performance and is currently the most widely used method.

[0004] The patent application document with publication number CN117645805A discloses a high-temperature oxidation-resistant gradient coating on the surface of tantalum-tungsten alloy, which is composed of a first coating material, a second coating material and a third coating material stacked in sequence; the components of the first coating material are: ZrB2 is 35~40wt%, HfB2 is 5~10wt%, 8YSZ is 11~16wt%, SiC is 2~5wt%, SiO2 is 2~4wt%, and the balance is Si; the components of the second coating material are: ZrB 2 is 30~35wt%, HfB2 is 10~15wt%, 8YSZ is 11~16wt%, SiC is 2~5wt%, SiO2 is 2~4wt%, La2Zr2O7 is 5~10wt%, and the balance is Si; the components of the third coating material are: ZrB2 is 25~30wt%, HfB2 is 15~20wt%, 8YSZ is 11~16wt%, SiC is 2~5wt%, SiO2 is 2~4wt%, La2Zr2O7 is 10~15wt%, and the balance is Si.

[0005] In this solution, the coating uses a high proportion of Si-based materials, which are easily softened at ultra-high temperatures, resulting in a decrease in structural stability. Although the low-viscosity glass phase generated by its oxidation is modified by rare earth doping, it is still difficult to completely suppress high-temperature loss. The gaseous products produced by SiC oxidation form potential pore channels inside the coating with reduced viscosity. Even if the composition is regulated through gradient design, the contradiction between gas escape and the dynamic balance of the glass phase cannot be resolved, causing the tantalum-tungsten alloy to fail due to oxidation, and the overall antioxidant performance of the coating is insufficient. Summary of the Invention

[0006] In order to improve the oxidation resistance of the coating, the present application provides a tantalum-tungsten alloy oxidation-resistant coating and a preparation process thereof.

[0007] In the first aspect, the present application provides a tantalum-tungsten alloy anti-oxidation coating, which adopts the following technical solution:

[0008] A tantalum-tungsten alloy anti-oxidation coating, comprising a transition layer, an inner layer, a barrier layer and an outer layer stacked in sequence;

[0009] The transition layer is prepared by co-sputtering an Ir target, a Ta target, and a Re target, wherein the sputtering power of the Ir target is P1W, the sputtering power of the Ta target is P2W, and the sputtering power of the Re target is P3W, and the ratio P1:P2:P3 is (12-18):(14-16):(5-7);

[0010] The inner layer is prepared by the following raw materials in parts by weight: 20-26 parts of Si, 24-6 parts of MoSi, 1.5-2.6 parts of Y, and 78-104 parts of Ta-W alloy powder;

[0011] The barrier layer is prepared from the following raw materials in parts by weight: 4-6 parts of Al2O3, 6-9 parts of Yb2O3, and 35-40 parts of 3YZrO2;

[0012] The outer layer is prepared from the following raw materials in parts by weight:

[0013] Composite: Yb2O3 25-30 parts, La2O3 30-35 parts, Gd2O3 40-45 parts, SiC 18-22 parts, B4C 1-1.5 parts;

[0014] Polynary boride: ZrB2 18~22 parts, HfB2 18~22 parts.

[0015] This technical solution constructs a high-performance antioxidant protection system for the surface of tantalum-tungsten alloy through the coordinated design of four-layer gradient functional coatings. The transition layer is co-sputtered with Ir, Ta, and Re. The high melting point of Ir and the ductility of Ta form a high-strength interface. Re dissolves in Ir and Ta, pinning grain boundaries and inhibiting high-temperature grain boundary diffusion. Re also enhances the creep resistance of the interface layer, reducing oxide film spalling during thermal cycling. Furthermore, the inner layer, based on Ta-W, provides a mechanical foundation for the coating system's thermal shock resistance. The compounded Si and MoSi2 preferentially oxidize to form a glassy phase at high temperatures, forming a dense oxidation barrier layer. The rare earth Y forms a composite oxide at the grain boundaries, inhibiting oxygen ion diffusion by refining grains and filling microcracks. The barrier layer creates a dual protection mechanism through the physical barrier of the high-melting-point oxides and the phase-transformation toughening effect of 3YZrO2. Al2O3 and Yb2O3 form a dense skeleton to inhibit oxygen penetration, and 3YZrO2 absorbs stress through phase change during thermal cycling, alleviating strain concentration inside the coating and improving thermal shock resistance.

[0016] The outer layer adopts a composite system of composite materials and multi-element borides. ZrB2 and HfB2 form discrete island-shaped ceramic skeletons, which provide ultra-high temperature structural support for the coating and resist mechanical loads such as high-speed airflow erosion. The composite partially reacts with the oxidation products of the boride at high temperature, melting in situ to generate a low-viscosity glass phase, which quickly fills the gaps and microcracks in the ceramic skeleton. The two work together to form a composite barrier, significantly improving the coating's oxidation resistance and durability in extreme high-temperature environments.

[0017] Preferably, the thickness of the transition layer is 5-8 μm.

[0018] Preferably, the thickness of the inner layer is 50-70 μm.

[0019] Preferably, the barrier layer has a thickness of 20-30 μm.

[0020] Preferably, the thickness of the outer layer is 70-90 μm.

[0021] Preferably, the inner layer further comprises 0.65 to 1.0 parts by mass of Ce.

[0022] In this technical solution, Ce, with its larger atomic radius, is concentrated at the grain boundaries, inhibiting grain coarsening and grain boundary migration at high temperatures, and reducing the diffusion rate of oxygen along the grain boundaries. At the same time, Ce is synergistically oxidized with Si, Y, etc. at high temperatures to form a dense composite oxide film. The generated CeO2 particles consume energy through microcrack deflection and stress dispersion effects, and can dynamically buffer the volume expansion stress during the oxidation process to a certain extent, reduce film cracking, effectively block oxygen penetration, and enhance the high-temperature oxidation resistance of the coating.

[0023] Preferably, the composite further comprises 3 to 5 parts by mass of LaBO3 and 0.5 to 1.5 parts by mass of B2O3.

[0024] In this technical solution, the LaBO3-B2O3 system forms a gradient viscosity glass phase, achieving real-time filling of microcracks and building an initial oxygen barrier; as the temperature rises, LaBO3, as a high-temperature stable phase, is embedded in the glass phase, reducing the volatilization and loss of B2O3 through physical barrier effect.

[0025] Preferably, the composite further comprises 2 to 4 parts by mass of nano Y3Al5O 12 .

[0026] Preferably, the nano Y3Al5O 12 Before use, the following pretreatment steps were performed:

[0027] Mix ZrOCl2·8H2O and water evenly, adjust the pH to 9-10, and obtain zirconium hydroxide sol. Then add nano Y3Al5O 12 and mix evenly, then transfer to a reactor, heat to 170-190°C, keep warm for 5.5-6.5h, cool, separate the solid and liquid, wash, dry, sinter at 550-650°C for 90-120min, cool, and obtain.

[0028] Preferably, the ZrOCl2·8H2O and nano Y3Al5O 12 The mass ratio is (1.6~3.2):(4.2~6.3).

[0029] This technical solution, nano Y3Al5O 12 The glass phase grain boundary migration is suppressed through the interface pinning effect, and its high-hardness particles are embedded in the matrix, forcing the microcrack propagation path to deflect, while the crack energy is consumed through the particle-matrix interface friction; the pre-treated coated ZrO2 nanolayer further alleviates the thermal mismatch stress and synergistically improves the density and toughness of the coating.

[0030] Preferably, the boride further comprises 4 to 6 parts by mass of TiB2.

[0031] In this technical solution, TiB2, as a high-melting-point boride, forms a gradient melting-point composite skeleton with ZrB2 and HfB2, and is preferentially oxidized at high temperatures to form a TiO2-B2O3 composite oxide layer, which hinders the diffusion of oxygen along the grain boundaries through a physical barrier, thereby improving the oxidation resistance and sealing of the coating.

[0032] In a second aspect, the present application further provides a process for preparing the above-mentioned tantalum-tungsten alloy anti-oxidation coating, comprising the following steps:

[0033] S1: Preparation of transition layer: Under an inert atmosphere, Ir target, Ta target and Re target are co-sputtered on the surface of the substrate, and then placed in a vacuum annealing furnace. In a weak reducing atmosphere, the temperature is raised to 1000-1200°C, kept at this temperature for 2-4 hours, and cooled to obtain the transition layer;

[0034] S2: Preparation of inner layer: Under an inert atmosphere, Ta-W alloy powder, Si, MoSi2 and Y are uniformly mixed to obtain composite powder A; composite powder A is then deposited on the surface of the metal transition layer using a plasma spraying device. After cooling, an inner layer is formed on the surface of the transition layer;

[0035] S3: Preparation of barrier layer: Al2O3, Yb2O3 and 3YZrO2 are uniformly mixed to obtain composite powder B, which is then deposited on the surface of the inner layer using a plasma spraying device and cooled to obtain a barrier layer formed on the surface of the inner layer;

[0036] S4: Preparation of outer layer:

[0037] (a) Yb2O3, La2O3, Gd2O3, SiC and B4C are mixed uniformly, sintered at 1400-1500°C for 1.5-2.5 hours, and cooled to obtain a pre-sintered composite;

[0038] (b) Under an inert atmosphere, ZrB2 and HfB2 were mixed uniformly, and then the pre-sintered composite was added and mixed uniformly to obtain composite powder C;

[0039] (c) In an inert atmosphere, composite powder C is deposited on the surface of the barrier layer by flame spraying. After cooling, an outer layer is formed on the surface of the barrier layer.

[0040] In this technical solution, the transition layer is prepared using Ir, Ta, and Re targets co-sputtered and combined with a hydrogen-argon annealing process to form a gradient interface that matches the tantalum-tungsten alloy substrate. The high melting point of Ir and the ductility of Ta synergistically create a high-strength substrate. Re enhances the high-temperature stability of the transition layer and reduces the chance of interfacial oxide film shedding. Annealing in a weakly reducing atmosphere reduces the interfacial oxide, promoting interdiffusion of elements to form a metallurgical bond. This effectively buffers the thermal expansion difference between the coating and the substrate, reducing interfacial thermal stress concentration. The inner layer, composed of Ta-W alloy powder as a framework, is plasma-sprayed with Si, MoSi2, and rare earth elements Y to form a composite protective structure. Si and MoSi2 oxidize to form a glassy phase, while the rare earth elements form composite oxides at grain boundaries, refining the grains and filling microcracks to inhibit oxygen ion diffusion. Ce, leveraging its atomic radius difference, creates an anchoring effect, inhibiting grain coarsening and optimizing the oxide film structure, achieving synergistic protection. The barrier layer combines the physical barrier of the high-melting-point oxide with the phase-transformation toughening effect of 3YZrO2 to create a dual protective mechanism. Al2O3 and Yb2O3 form a dense skeleton to inhibit oxygen penetration, and 3YZrO2 absorbs stress through phase change during thermal cycling, alleviating strain concentration inside the coating and improving thermal shock resistance.

[0041] The outer layer is a composite of pre-sintered composites and multi-component borides. After pre-sintering, the composite can optimize its physical structure, reduce microscopic defects and promote solid-phase reactions with SiC, etc., to form a more uniform glass phase precursor; when compounded with borides, the pre-sintered products can be quickly fused with the oxides of the borides, etc., to form a dense glass phase in situ to fill the gaps in the ceramic skeleton, avoid component segregation, achieve dynamic sealing at high temperatures, and significantly improve the coating's oxidation resistance and structural stability.

[0042] Preferably, in step S1, the weak reducing atmosphere is a mixture of argon and hydrogen, and the volume ratio of argon to hydrogen is (90-95):(5-10).

[0043] Preferably, the preparation of the inner layer further comprises the step of adding Ce when adding Y.

[0044] Preferably, in step S4, after the step of adding SiC, the step of adding LaBO3 and B2O3 is further included.

[0045] Preferably, in step S4, after adding SiC, nano Y3Al5O 12 steps.

[0046] Preferably, in step S4, after the HfB2 step, a step of adding TiB2 is also included.

[0047] In summary, this application has the following beneficial effects:

[0048] This application uses an Ir-Ta-Re transition layer combined with a hydrogen-argon annealing process to achieve metallurgical bonding between the coating and the substrate, effectively alleviating the thermal expansion mismatch problem and laying a stable foundation for the entire protection system; furthermore, the coordinated design of the inner layer, barrier layer and outer layer realizes the self-healing function of the oxide film and significantly enhances the high-temperature oxidation resistance; at the same time, by optimizing the material composition and structure, the coating's resistance to high-speed airflow erosion and thermal shock is improved to meet the complex environmental requirements under extreme working conditions. DETAILED DESCRIPTION

[0049] The present application is further described in detail below with reference to the embodiments.

[0050] Unless otherwise specified, the raw materials used in the examples and comparative examples of the present application are all commercially available.

[0051] Limited raw materials:

[0052] Tantalum-tungsten alloy substrate: Ta10W, size φ100×2mm, surface roughness Ra=1.6μm;

[0053] Tantalum tungsten alloy substrates undergo the following pretreatment steps before use:

[0054] The surface was polished with 240-mesh, 600-mesh, and 1200-mesh sandpaper to Ra ≤ 0.8 μm, and then transferred to an ultrasonic device with an ultrasonic power of 300 W and a frequency of 40 kHz. It was cleaned with acetone for 15 min and ethanol for 15 min, and then transferred to a plasma cleaning machine for argon ion bombardment for 20 min with a voltage of 3 kV and a current of 50 mA. The vacuum degree of the chamber was about 10 -2 ~10 -3 Pa, the surface oxygen content of the finally obtained tantalum-tungsten alloy substrate is not higher than 0.1at%, and is ready for use.

[0055] Ir target, purity 99.95%, φ100×6mm; Ta target 99.95%, φ100×6mm; Re target 99.9%; φ100×6mm;

[0056] Si powder, 325 mesh sieve, purity 99.5%; Y powder, 325 mesh sieve, purity 99.9%; Ta-W alloy powder is Ta10W alloy powder, purity 99.5%, 325 mesh sieve; Ce powder, 325 mesh sieve, purity 99.9%; Al2O3 powder, 325 mesh sieve, purity 99.9%; Yb2O3 powder, 325 mesh sieve, purity 99.99%; 3YZrO2 powder, 325 mesh sieve, purity 99.9%; ZrB2 powder, 325 mesh sieve Sieve undersize, purity 99.5%; HfB2 powder, 325 mesh undersize, purity 99.5%; TiB2 powder, 325 mesh undersize, purity 99.5%; La2O3 powder, 325 mesh undersize, purity 99.99%; Gd2O3 powder, 325 mesh undersize, purity 99.99%; SiC powder, 325 mesh undersize, purity 99.9%; B2O3 powder, 325 mesh undersize, purity 99.5%; LaBO3, 325 mesh undersize, purity 99%; Y3Al5O 12 , particle size distribution 10~100nm, purity 99.99%.

[0057] Pretreatment Preparation Example 1

[0058] The nano Y3Al5O 12 Before use, the following pretreatment steps were performed:

[0059] Take 0.24g ZrOCl2·8H2O and dissolve it in 5mL deionized water. Use 25% ammonia water to adjust the pH to 9.5 to obtain zirconium hydroxide sol. Then add 0.5g nano Y3Al5O 12 The powder was transferred into an ultrasonic device and ultrasonicated for 40 minutes at a power of 200 W and a frequency of 40 kHz. The powder was then transferred to a polytetrafluoroethylene-lined reactor, heated to 180°C at a rate of 5°C / min, kept warm for 6 hours, and naturally cooled to room temperature. The product was then centrifuged and the precipitate was collected. The product was washed twice with deionized water and once with an ethanol-deionized water mixture with a volume ratio of 1:1. The product was then transferred to a 60°C oven and dried for 6 hours. The product was then transferred to a sintering furnace, heated to 600°C at a rate of 10°C / min, kept warm for 110 minutes, and cooled to room temperature with the furnace.

[0060] Among them, nano Y3Al5O 12 Before use, the powder was dried in an oven at 120°C for 2 h.

[0061] Pretreatment Preparation Example 2

[0062] The nano Y3Al5O 12 Before use, the following pretreatment steps were performed:

[0063] Take 0.16g ZrOCl2·8H2O and dissolve it in 5mL deionized water. Use 25% ammonia water to adjust the pH to 9 to obtain zirconium hydroxide sol. Then add 0.42g nano Y3Al5O 12 The powder was transferred into an ultrasonic device and ultrasonicated for 35 minutes at a power of 200 W and a frequency of 40 kHz. The powder was then transferred to a polytetrafluoroethylene-lined reactor, heated to 170°C at a rate of 5°C / min, kept warm for 6.5 hours, and naturally cooled to room temperature. The product was then centrifuged and the precipitate was collected. The precipitate was washed twice with deionized water and once with an ethanol-deionized water mixture with a volume ratio of 1:1. The product was then transferred to a 60°C oven and dried for 5 hours. The product was then transferred to a sintering furnace, heated to 550°C at a rate of 10°C / min, kept warm for 120 minutes, and cooled to room temperature with the furnace.

[0064] Among them, nano Y3Al5O 12 Before use, the powder was dried in an oven at 120°C for 2 h.

[0065] Pretreatment Preparation Example 3

[0066] The nano Y3Al5O 12 Before use, the following pretreatment steps were performed:

[0067] Take 0.32g ZrOCl2·8H2O and dissolve it in 5mL deionized water. Use 25% ammonia water to adjust the pH to 10 to obtain zirconium hydroxide sol. Then add 0.63g nano Y3Al5O 12 The powder was transferred into an ultrasonic device, ultrasonicated at a power of 200 W and a frequency of 40 kHz for 45 minutes, then transferred to a polytetrafluoroethylene-lined reactor, heated to 190°C at a rate of 5°C / min, kept warm for 5.5 hours, naturally cooled to room temperature, centrifuged, and the precipitate was collected. The precipitate was washed twice with deionized water, and then washed once with an ethanol-deionized water mixture with a volume ratio of 1:1. The precipitate was transferred to a 60°C oven and dried for 8 hours. The precipitate was then transferred to a sintering furnace, heated to 650°C at a rate of 10°C / min, kept warm for 90 minutes, and cooled to room temperature with the furnace.

[0068] Among them, nano Y3Al5O 12 Before use, the powder was dried in an oven at 120°C for 2 h.

[0069] Example 1

[0070] The preparation process of the tantalum-tungsten alloy anti-oxidation coating of this embodiment includes the following steps:

[0071] S1: Preparation of transition layer:

[0072] Under argon atmosphere, the pretreated tantalum-tungsten alloy substrate was placed in a vacuum chamber and preheated to 300 °C. The power of the Ir target was set to 150 W, the power of the Ta target was set to 150 W, the power of the Re target was set to 60 W, the sputtering pressure was 0.4 Pa, and the sputtering thickness was about 6 μm. After the sputtering was completed, it was cooled to 50 °C, taken out and transferred to a vacuum annealing furnace, and evacuated to 1×10 -4 Pa, then introduce a mixture of argon and hydrogen, with a volume ratio of argon to hydrogen of 92:8 and a total gas flow rate of 100 mL / min, heat to 1100°C at a rate of 8°C / min, hold for 3 h, and cool to room temperature with the furnace to obtain a transition layer formed on the surface of the substrate;

[0073] S2: Preparation of inner layer:

[0074] Under argon atmosphere, 9.1 g of Ta10W alloy powder, 2.4 g of silicon powder, 0.5 g of MoSi2 and 0.208 g of Y powder were weighed and placed in a ball mill and milled at 300 rpm for 8 h to obtain composite powder A.

[0075] Then, plasma spraying equipment is used to spray the surface of the transition layer four times. After each spraying, it is cooled for 3 minutes. The spraying thickness is about 60 μm. After the spraying is completed, it is naturally cooled to room temperature to form an inner layer on the surface of the transition layer.

[0076] S3: Preparation of barrier layer:

[0077] Weigh 0.5g of Al2O3, 0.75g of Yb2O3 and 3.75g of 3YZrO2 and place them in a ball mill and mill them at 300rpm for 4h to obtain composite powder B; then use plasma spraying equipment to spray them twice, with an interval of 3min each time, and the spraying thickness is about 25μm.

[0078] After spraying, the coating is cooled naturally to room temperature to obtain a barrier layer formed on the surface of the inner layer;

[0079] S4: Preparation of outer layer:

[0080] (a) Yb2O3 2.7 g, La2O3 3.2 g, Gd2O3 4.2 g, SiC 2.0 g, and B4C 0.12 g were weighed and placed in a ball mill. After ball milling at 300 rpm for 4 h, the mixture was placed in an ark and transferred to a sintering furnace. The temperature was increased to 1450°C at 10°C / min and sintered for 2 h. The mixture was cooled to room temperature in the furnace and then ground again until it completely passed through a 325-mesh sieve to obtain a pre-sintered composite.

[0081] (b) Under argon atmosphere, 2.0 g of ZrB2 and 2.0 g of HfB2 were weighed and placed in a ball mill. After ball milling at 300 rpm for 3 h, the pre-sintered composite was added and milling continued for 60 min to obtain composite powder C.

[0082] (c) In an argon atmosphere, a supersonic flame spraying device is used for five spraying operations with a chamber pressure of 0.6 kPa and an interval of 5 minutes between each spraying. The spraying thickness is about 80 μm. After the spraying is completed, the coating is naturally cooled to room temperature to form an outer layer on the surface of the barrier layer.

[0083] Example 2

[0084] The preparation process of the tantalum-tungsten alloy anti-oxidation coating of this embodiment includes the following steps:

[0085] S1: Preparation of transition layer:

[0086] Under argon atmosphere, the pretreated tantalum-tungsten alloy substrate was placed in a vacuum chamber and preheated to 280°C. The power of the Ir target was set to 120W, the power of the Ta target was set to 140W, the power of the Re target was set to 50W, the sputtering pressure was set to 0.35Pa, and the sputtering thickness was about 5μm. After the sputtering was completed, it was cooled to 50°C, taken out and transferred to a vacuum annealing furnace, and the vacuum degree was evacuated to 1×10 -4 Pa, then introduce a mixture of argon and hydrogen, with a volume ratio of argon to hydrogen of 95:5 and a total gas flow rate of 100 mL / min, heat to 1050°C at a rate of 5°C / min, hold for 4 h, and cool to room temperature with the furnace to obtain a transition layer formed on the surface of the substrate;

[0087] S2: Preparation of inner layer:

[0088] Under argon atmosphere, 7.8 g of Ta10W alloy powder, 2.0 g of silicon powder, 0.4 g of MoSi2 and 0.156 g of Y powder were weighed and placed in a ball mill and ball milled at 300 rpm for 8 h to obtain composite powder A;

[0089] Then, plasma spraying equipment is used for three times of spraying. After each spraying, cooling is performed for 3 minutes. The spraying thickness is about 50 μm. After spraying, the coating is naturally cooled to room temperature to obtain an inner layer formed on the surface of the transition layer.

[0090] S3: Preparation of barrier layer:

[0091] Weigh 0.4g of Al2O3, 0.6g of Yb2O3 and 3.5g of 3YZrO2 and place them in a ball mill and mill them at 300rpm for 4h to obtain composite powder B; then use plasma spraying equipment to spray them twice, with an interval of 3min each time, and the spraying thickness is about 20μm.

[0092] After spraying, the coating is cooled naturally to room temperature to obtain a barrier layer formed on the surface of the inner layer;

[0093] S4: Preparation of outer layer:

[0094] (a) 2.5 g of Yb2O3, 3 g of La2O3, 4 g of Gd2O3, 1.8 g of SiC, and 0.1 g of B4C were weighed and placed in a ball mill. After ball milling at 300 rpm for 4 h, the mixture was placed in an ark and transferred to a sintering furnace. The temperature was increased to 1450°C at a rate of 10°C / min and sintered for 2 h. The mixture was cooled to room temperature in the furnace and then ground again until it completely passed through a 325-mesh sieve to obtain a pre-sintered composite.

[0095] (b) Under argon atmosphere, ZrB21.8g and HfB22.2g were weighed and placed in a ball mill. After ball milling at 300 rpm for 3 h,

[0096] Add the pre-sintered composite and continue grinding for 60 min to obtain composite powder C;

[0097] (c) In an argon atmosphere, a supersonic flame spraying device is used for four spraying operations with a chamber pressure of 0.6 kPa and an interval of 5 minutes between each spraying. The spraying thickness is about 70 μm. After the spraying is completed, the coating is naturally cooled to room temperature to form an outer layer on the surface of the barrier layer.

[0098] Example 3

[0099] The preparation process of the tantalum-tungsten alloy anti-oxidation coating of this embodiment includes the following steps:

[0100] S1: Preparation of transition layer:

[0101] Under argon atmosphere, the pretreated tantalum-tungsten alloy substrate was placed in a vacuum chamber and preheated to 320°C. The power of the Ir target was set to 180W, the power of the Ta target was set to 160W, the power of the Re target was set to 70W, the sputtering pressure was 0.45Pa, and the sputtering thickness was about 8μm. After the sputtering was completed, it was cooled to 50°C, taken out and transferred to a vacuum annealing furnace, and the vacuum degree was evacuated to 0.8×10 -4 Pa, then introduce a mixture of argon and hydrogen, with a volume ratio of argon to hydrogen of 90:10 and a total gas flow rate of 100 mL / min, heat to 1150°C at a rate of 5°C / min, hold for 4 h, and cool to room temperature with the furnace to obtain a transition layer formed on the surface of the substrate;

[0102] S2: Preparation of inner layer:

[0103] Under argon atmosphere, 10.4 g of Ta10W alloy powder, 2.6 g of silicon powder, 0.6 g of MoSi2 and 0.26 g of Y powder were weighed and placed in a ball mill and ball milled at 300 rpm for 8 h to obtain composite powder A;

[0104] Then, plasma spraying equipment is used to spray the coating five times, with a cooling interval of 3 minutes each time. The coating thickness is about 70 μm. After the coating is completed, the coating is naturally cooled to room temperature to obtain an inner layer formed on the surface of the transition layer.

[0105] S3: Preparation of barrier layer:

[0106] 0.6 g of Al2O3, 0.9 g of Yb2O3, and 4 g of 3YZrO2 were weighed and placed in a ball mill and milled at 300 rpm for 4 hours to obtain composite powder B. The composite powder B was then sprayed using a plasma spraying device in three passes, with an interval of 3 minutes between each pass. The spraying thickness was approximately 30 μm. After the spraying was completed, the composite powder was naturally cooled to room temperature to obtain a barrier layer formed on the surface of the inner layer.

[0107] S4: Preparation of outer layer:

[0108] (a) Yb2O33 g, La2O33.5 g, Gd2O34.5 g, SiC2.2 g, and B4C0.15 g were weighed and placed in a ball mill. After ball milling at 300 rpm for 4 h, the mixture was placed in an ark and transferred to a sintering furnace. The temperature was increased to 1450°C at a rate of 10°C / min and sintered for 2 h. The mixture was cooled to room temperature in the furnace and then ground again until it completely passed through a 325-mesh sieve to obtain a pre-sintered composite.

[0109] (b) Under argon atmosphere, ZrB2 2.2 g and HfB2 1.8 g were weighed and placed in a ball mill. After ball milling at 300 rpm for 3 h, the pre-sintered composite was added and milling continued for 60 min to obtain composite powder C.

[0110] (c) In an argon atmosphere, a supersonic flame spraying device is used for six spraying operations with a chamber pressure of 0.6 kPa and an interval of 5 minutes between each spraying. The spraying thickness is about 90 μm. After the spraying is completed, the coating is naturally cooled to room temperature to form an outer layer on the surface of the barrier layer.

[0111] Example 4

[0112] The difference between this embodiment and embodiment 1 is that:

[0113] In step S2, when adding Y powder, the step of adding 0.065 g of Ce powder is also included.

[0114] Other details are the same as in Example 1.

[0115] Example 5

[0116] The difference between this embodiment and embodiment 4 is that:

[0117] In step S2, the amount of Ce powder used is 0.1 g;

[0118] In step S4, after the step of adding SiC, the step of adding 0.3g LaBO3 and 0.05g B2O3 is also included.

[0119] Other details are the same as in Example 4.

[0120] Example 6

[0121] The difference between this embodiment and embodiment 5 is that:

[0122] In step S4, the amount of LaBO3 is 0.5g, and the amount of B2O3 is 0.15g;

[0123] In step S4, after adding SiC, 0.2g of nano Y3Al5O 12 steps.

[0124] Nano Y3Al5O 12 From Pretreatment Preparation Example 1;

[0125] Other details are the same as in Example 5.

[0126] Example 7

[0127] The difference between this embodiment and embodiment 6 is that:

[0128] In step S4, nano Y3Al5O 12 The dosage is 0.3g.

[0129] In step S4, after adding HfB2, 0.4 g of TiB2 is also added;

[0130] Nano Y3Al5O 12 From Pretreatment Preparation Example 2;

[0131] Other details are the same as in Example 6.

[0132] Example 8

[0133] The difference between this embodiment and embodiment 7 is that:

[0134] In step S4, nano Y3Al5O 12 The dosage is 0.4g.

[0135] In step S4, the amount of TiB2 used is 0.6 g;

[0136] Nano Y3Al5O 12 From Pretreatment Preparation Example 3;

[0137] Other details are the same as in Example 7.

[0138] Comparative Example 1

[0139] The preparation process of the tantalum-tungsten alloy anti-oxidation coating of this comparative example includes the following steps:

[0140] S1: Preparation of inner layer:

[0141] Under argon atmosphere, 9.1 g of Ta10W alloy powder, 2.4 g of silicon powder, 0.5 g of MoSi2 and 0.208 g of Y powder were weighed and placed in a ball mill and milled at 300 rpm for 8 h to obtain composite powder A.

[0142] Then, plasma spraying equipment is used to spray the substrate surface four times. After each spraying, it is cooled for 3 minutes. The spraying thickness is about 60 μm. After the spraying is completed, it is naturally cooled to room temperature to form an inner layer on the substrate surface.

[0143] S2: Preparation of barrier layer:

[0144] Weigh 0.5g of Al2O3, 0.75g of Yb2O3 and 3.75g of 3YZrO2 and place them in a ball mill and mill them at 300rpm for 4h to obtain composite powder B; then use plasma spraying equipment to spray them twice, with an interval of 3min each time, and the spraying thickness is about 25μm.

[0145] After spraying, the coating is cooled naturally to room temperature to obtain a barrier layer formed on the surface of the inner layer;

[0146] S3: Preparation of outer layer:

[0147] (a) Yb2O3 2.7 g, La2O3 3.2 g, Gd2O3 4.2 g, SiC 2.0 g, and B4C 0.12 g were weighed and placed in a ball mill. After ball milling at 300 rpm for 4 h, the mixture was placed in an ark and transferred to a sintering furnace. The temperature was increased to 1450°C at 10°C / min and sintered for 2 h. The mixture was cooled to room temperature in the furnace and then ground again until it completely passed through a 325-mesh sieve to obtain a pre-sintered composite.

[0148] (b) Under argon atmosphere, 2.0 g of ZrB2 and 2.0 g of HfB2 were weighed and placed in a ball mill. After ball milling at 300 rpm for 3 h, the pre-sintered composite was added and milling continued for 60 min to obtain composite powder C.

[0149] (c) In an argon atmosphere, a supersonic flame spraying device is used for five spraying operations with a chamber pressure of 0.6 kPa and an interval of 5 minutes between each spraying. The spraying thickness is about 80 μm. After the spraying is completed, the coating is naturally cooled to room temperature to form an outer layer on the surface of the barrier layer.

[0150] Comparative Example 2

[0151] The difference between this comparative example and Example 1 is:

[0152] S1: Preparation of transition layer:

[0153] Under argon atmosphere, the pretreated tantalum-tungsten alloy substrate was placed in a vacuum chamber and preheated to 300 °C. The power of the Ir target was set to 150 W, the power of the Ta target was set to 150 W, the power of the Re target was set to 60 W, the sputtering pressure was 0.4 Pa, and the sputtering thickness was about 6 μm. After the sputtering was completed, it was cooled to 50 °C, taken out and transferred to a vacuum annealing furnace, and evacuated to 1×10 -4 Pa, then introduce argon gas at a flow rate of 100 mL / min, raise the temperature to 1100°C at a rate of 8°C / min, keep the temperature for 3 h, and cool to room temperature with the furnace to obtain a transition layer formed on the surface of the substrate;

[0154] Other details are the same as in Example 1.

[0155] Comparative Example 3

[0156] The difference between this comparative example and Example 1 is:

[0157] S2: Preparation of inner layer:

[0158] Under argon atmosphere, 9.1 g of Ta10W alloy powder and 2.4 g of silicon powder were weighed and placed in a ball mill and milled at 300 rpm for 8 h to obtain composite powder A.

[0159] Then, plasma spraying equipment is used to spray the surface of the transition layer four times. After each spraying, it is cooled for 3 minutes. The spraying thickness is about 60 μm. After the spraying is completed, it is naturally cooled to room temperature to form an inner layer on the surface of the transition layer.

[0160] Other details are the same as in Example 1.

[0161] Comparative Example 4

[0162] The difference between this comparative example and Example 1 is:

[0163] S4: Preparation of outer layer:

[0164] (a) In an argon atmosphere, Yb2O3 2.7 g, La2O3 3.2 g, Gd2O3 4.2 g, SiC 2.0 g, B4C 0.12 g, ZrB2 2.0 g, and HfB2 2.0 g were weighed and placed in a ball mill. After ball milling at 300 rpm for 4 h, composite powder C was obtained.

[0165] (c) In an argon atmosphere, a supersonic flame spraying device is used for five spraying operations with a chamber pressure of 0.6 kPa and an interval of 5 minutes between each spraying. The spraying thickness is about 80 μm. After the spraying is completed, the coating is naturally cooled to room temperature to form an outer layer on the surface of the barrier layer.

[0166] Other details are the same as in Example 1.

[0167] Performance testing

[0168] The tantalum-tungsten alloy anti-oxidation coating samples prepared in Examples 1 to 8 and Comparative Examples 1 to 4 were respectively subjected to anti-oxidation performance tests, and the test data are shown in Table 1 below.

[0169] Table 1 Performance test data of tantalum-tungsten alloy anti-oxidation coating samples prepared in Examples 1 to 8 and Comparative Examples 1 to 4

[0170]

[0171] From Table 1 we can see that:

[0172] Examples 1 to 8 construct a transition layer by co-sputtering Ir-Ta-Re and combining it with a hydrogen-argon annealing process. By virtue of the solid solution strengthening effect of Re on Ir and the reduction of interface oxides by hydrogen, the interface thermal stress between the coating and the substrate is effectively buffered. At the same time, the inner layer uses Ta-W alloy powder as the skeleton, and the high-temperature softening temperature is increased by replacing part of Si with MoSi2. The rare earth elements optimize the grain boundary oxidation behavior to form a composite protective structure. The barrier layer is based on the composite system of Al2O3, Yb2O3 and 3YZrO2. The physical barrier effect of high-melting-point oxides inhibits the diffusion of oxygen atoms. At the same time, the tetragonal-monoclinic phase transition of 3YZrO2 absorbs thermal stress and relieves the internal strain concentration of the coating. The outer layer is formed by pre-sintering the composite with borides such as ZrB2 and HfB2 to form a dense glass phase sealing layer at high temperature, combined with nano Y3Al5O 12 The surface-coated ZrO2 nanolayer enhances interfacial bonding and improves thermal shock resistance. In contrast, Comparative Example 1 omitted the transition layer, resulting in concentrated thermal stress at the interface, which became the primary channel for oxygen permeation. Comparative Example 2 lacked hydrogen flow, resulting in a residual oxide film on the interface that exacerbated element diffusion. Comparative Example 3 lacked MoSi2 and Y powder, causing high-temperature creep softening of the inner layer. Comparative Example 4 failed to pre-sinter the outer layer, leading to component segregation and a weak link for oxygen permeation.

[0173] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A tantalum-tungsten alloy anti-oxidation coating, characterized in that: The tantalum-tungsten alloy anti-oxidation coating comprises a transition layer, an inner layer, a barrier layer and an outer layer stacked in sequence; The transition layer is prepared by co-sputtering an Ir target, a Ta target, and a Re target, wherein the sputtering power of the Ir target is P1W, the sputtering power of the Ta target is P2W, and the sputtering power of the Re target is P3W, and the ratio P1:P2:P3 is (12-18):(14-16):(5-7); The inner layer is prepared by the following raw materials in parts by weight: 20-26 parts of Si, 4-6 parts of MoSi2, 1.5-2.6 parts of Y, and 78-104 parts of Ta-W alloy powder; The barrier layer is prepared from the following raw materials in parts by weight: 4-6 parts of Al2O3, 6-9 parts of Yb2O3, and 35-40 parts of 3YZrO2; The outer layer is prepared from the following raw materials in parts by weight: Composite: Yb2O3 25-30 parts, La2O3 30-35 parts, Gd2O3 40-45 parts, SiC 18-22 parts, B4C 1-1.5 parts; Polynary boride: ZrB2 18~22 parts, HfB2 18~22 parts.

2. The tantalum-tungsten alloy anti-oxidation coating according to claim 1, characterized in that: The inner layer further includes 0.65 to 1.0 parts by mass of Ce.

3. The tantalum-tungsten alloy anti-oxidation coating according to claim 1, characterized in that: The composite further comprises 3 to 5 parts by mass of LaBO3 and 0.5 to 1.5 parts by mass of B2O3.

4. The tantalum-tungsten alloy anti-oxidation coating according to claim 1, characterized in that: The composite further comprises 2 to 4 parts by mass of nano Y3Al5O 12 .

5. The tantalum-tungsten alloy anti-oxidation coating according to claim 4, characterized in that: The nano Y3Al5O 12 Before use, the following pretreatment steps were performed: Mix ZrOCl2·8H2O and water evenly, adjust the pH to 9-10, and obtain zirconium hydroxide sol. Then add nano Y3Al5O 12 and mix evenly, then transfer to a reactor, heat to 170-190°C, keep warm for 5.5-6.5h, cool, separate the solid and liquid, wash, dry, sinter at 550-650°C for 90-120min, cool, and obtain.

6. A process for preparing the tantalum-tungsten alloy anti-oxidation coating according to claim 1, characterized in that: The steps include: S1: Preparation of transition layer: Under an inert atmosphere, Ir target, Ta target and Re target are co-sputtered on the surface of the substrate, and then placed in a vacuum annealing furnace. In a weak reducing atmosphere, the temperature is raised to 1000-1200°C, kept at this temperature for 2-4 hours, and cooled to obtain the transition layer; S2: Preparation of inner layer: Under an inert atmosphere, Ta-W alloy powder, Si, MoSi2 and Y are uniformly mixed to obtain composite powder A; composite powder A is then deposited on the surface of the metal transition layer using a plasma spraying device. After cooling, an inner layer is formed on the surface of the transition layer; S3: Preparation of barrier layer: Al2O3, Yb2O3 and 3YZrO2 are uniformly mixed to obtain composite powder B, which is then deposited on the surface of the inner layer using a plasma spraying device and cooled to obtain a barrier layer formed on the surface of the inner layer; S4: Preparation of outer layer: (a) Yb2O3, La2O3, Gd2O3, SiC and B4C are mixed uniformly, sintered at 1400-1500°C for 1.5-2.5 hours, and cooled to obtain a pre-sintered composite; (b) Under an inert atmosphere, ZrB2 and HfB2 were mixed uniformly, and then the pre-sintered composite was added and mixed uniformly to obtain composite powder C; (c) In an inert atmosphere, composite powder C is deposited on the surface of the barrier layer by flame spraying. After cooling, an outer layer is formed on the surface of the barrier layer.

7. The process for preparing the tantalum-tungsten alloy anti-oxidation coating according to claim 6, characterized in that: The weak reducing atmosphere is a mixture of argon and hydrogen, and the volume ratio of argon to hydrogen is (90-95): (5-10).

8. The process for preparing the tantalum-tungsten alloy anti-oxidation coating according to claim 6, characterized in that: In step S2, when Y is added, a step of adding Ce is also included.

9. The process for preparing the tantalum-tungsten alloy anti-oxidation coating according to claim 6, characterized in that: In step S4, after the step of adding SiC, the step of adding LaBO3 and B2O3 is also included.

10. The process for preparing the tantalum-tungsten alloy anti-oxidation coating according to claim 6, characterized in that: In step S4, after adding SiC, nano Y3Al5O 12 steps.

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