A CMAS corrosion resistant thermal barrier coating containing vertical cracks and a method of making the same

Abstract

The present application belongs to the technical field of thermal barrier coatings, and particularly relates to a CMAS corrosion resistant thermal barrier coating containing vertical cracks and a preparation method thereof. The strain buffer interlayer is composed of yttrium oxide stabilized zirconium containing in-situ generated rare earth aluminate lamellae; the functional composite top layer is composed of alumina particles coated with an amorphous silicon oxide layer and a niobium-samarium co-doped yttrium oxide stabilized zirconium matrix; the coating contains vertical cracks penetrating through the functional composite top layer and ending in the strain buffer interlayer. The preparation method comprises the following steps: depositing a metal bonding layer, depositing a strain buffer interlayer, depositing a functional composite top layer, and performing post-processing to induce vertical cracks. The present application synchronously solves the performance contradiction between thermal shock resistance and CMAS corrosion resistance of the thermal barrier coating by synergistically regulating the macroscopic crack network, micron-scale toughening structure and nanoscale strong and tough interface of the coating.

Description

Technical Field

[0001] This invention belongs to the field of thermal barrier coating technology, specifically relating to a thermal barrier coating containing vertical cracks that is resistant to CMAS corrosion and its preparation method. Background Technology

[0002] Thermal barrier coatings (TBCs) are widely used to protect metal components from calcium magnesium silicate corrosion (CMAS, CaO-MgO-Al2O3-SiO2) under high-temperature operation. Failure caused by the erosion of molten deposits is one of the key challenges in improving the performance of aero-engines. By depositing a ceramic layer with extremely low thermal conductivity (usually yttrium-stabilized zirconia, or YSZ coating) on ​​the surface of a high-temperature alloy substrate, the operating temperature of the substrate can be effectively reduced by more than 100°C, thereby significantly improving the upper limit of the service temperature of the component, its durability, and engine efficiency. With the continuous improvement of the requirements for engine thrust-to-weight ratio and thermal efficiency, the turbine inlet temperature is increasing, and thermal barrier coatings face the dual severe challenges of thermomechanical stress and environmental corrosion. Existing technologies have significant bottlenecks in synergistically optimizing these performance characteristics.

[0003] In terms of thermal shock resistance, traditional YSZ coatings experience significant cyclic thermal stress during drastic start-up and shutdown temperature cycles due to the substantial difference in thermal expansion coefficients between the ceramic layer and the metal substrate. This easily leads to the initiation and propagation of horizontal cracks parallel to the interface within the coating, ultimately causing coating spalling failure. To mitigate this problem, the industry has attempted to introduce vertical cracks into the coating to segment the ceramic layer and release strain energy. Common methods include adjusting the process parameters of atmospheric plasma spraying to directly form microcracks during deposition. However, the density, depth, and uniformity of crack distribution formed by such methods are difficult to control precisely, and the crack morphology exhibits considerable randomness. More importantly, the interface of these process-induced cracks is relatively fresh, and under long-term high-temperature service, their tips may become new stress concentration points, or even provide rapid channels for the penetration of corrosive media, potentially accelerating coating failure in the long run. Therefore, current technology lacks a method for controllably preparing vertical crack structures that combine good stress release effects with structural stability.

[0004] In resisting calcium magnesium aluminum silicate corrosion, the penetration and chemical reaction of CMAS melt into traditional YSZ coatings are the main causes of their premature failure. To improve corrosion resistance, the most direct technical approach is to introduce thermodynamically stable phases such as alumina into the coating surface. The current mainstream approach is to use a physical-mechanical mixing method to mix alumina particles with YSZ powder before spraying. However, this method has inherent drawbacks: on the one hand, the physically mixed alumina particles and the YSZ matrix are mainly mechanically interlocked or weakly bonded by van der Waals forces, resulting in low interfacial bonding strength. Under thermal stress, this bonding is prone to debonding, becoming the origin of microcracks. On the other hand, the difference in thermal expansion coefficients between alumina and YSZ introduces additional residual interfacial stress. In practice, it has been found that CMAS melt tends to penetrate rapidly along this weakly bonded interface, meaning that the addition of alumina particles not only fails to effectively block corrosion but may also degrade the overall density and mechanical integrity of the coating. Therefore, achieving a strong and tough metallurgical bond between the corrosion-resistant reinforcing phase and the ceramic matrix is ​​key to overcoming the performance limitations of existing simple physical mixing methods.

[0005] Furthermore, to simultaneously pursue thermal shock resistance and corrosion resistance in coatings, existing technologies have seen the emergence of more complex multilayer or functionally graded coating designs. These designs typically involve the complex preparation of multiple functional powders, multiple or various spraying processes, and cumbersome post-treatment. They generally suffer from problems such as long process routes, high costs, and difficulty in precisely controlling the interfacial bonding quality between layers and the final coating performance stability. For example, powders involving rare earth element modification, if prepared using only simple mechanical alloying, are prone to uneven distribution of active components. During the high-temperature instantaneous process of spraying, the expected uniform in-situ reaction cannot be achieved, resulting in the inability to form or poor distribution of the designed reinforcing phase, and the failure to achieve the desired performance improvement.

[0006] Therefore, it is necessary to design a thermal barrier coating with vertical cracks that is resistant to CMAS corrosion and its preparation method. Summary of the Invention

[0007] To overcome the shortcomings of the prior art, a thermal barrier coating containing vertical cracks resistant to CMAS corrosion and its preparation method are provided.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] A thermal barrier coating resistant to CMAS corrosion containing vertical cracks, the coating comprising, from the substrate outwards, a metal bonding layer, a strain buffer intermediate layer and a functional composite top layer, wherein the strain buffer intermediate layer is composed of yttrium-stabilized zirconium oxide containing in-situ generated rare earth aluminate lamellar crystals.

[0010] The functional composite top layer is composed of alumina particles coated with an amorphous silicon oxide layer and a niobium-sammarium co-doped yttrium-stabilized zirconium oxide matrix.

[0011] The coating contains vertical cracks that penetrate the functional composite top layer and terminate in the strain-buffered intermediate layer.

[0012] The thickness of the metal bonding layer is 80-150 micrometers; the thickness of the strain buffer intermediate layer is 180-250 micrometers; the thickness of the functional composite top layer is 200-280 micrometers; and the linear density of the vertical cracks on the surface of the functional composite top layer is 3.0-4.0 cracks / mm.

[0013] The strain buffer intermediate layer is obtained by processing yttrium oxide-stabilized zirconia composite powder modified with rare earth oxides. The preparation method of the rare earth oxide-modified yttrium oxide-stabilized zirconia composite powder includes the following steps:

[0014] a. Weigh out yttrium oxide stabilized zirconium oxide powder, wherein the molar fraction of yttrium oxide is 7-8% and the powder particle size D50 is 15-25 micrometers;

[0015] b. Preparation of nitrate solution: Dissolve gadolinium nitrate hexahydrate and yttrium nitrate hexahydrate in anhydrous ethanol at a molar ratio of Gd to Y of 1:1 to 2:1 to prepare a nitrate ethanol solution with a total metal ion concentration of 0.2-0.4 mol / L.

[0016] c. Solution impregnation and primary drying: The yttrium-stabilized zirconia powder from step a is placed in a fluidized bed. At 40-60°C, the nitrate ethanol solution from step b is loaded onto the surface of the yttrium-stabilized zirconia powder by atomization spraying. Then, it is dried at 80-100°C for 10-14 hours to obtain a primary dried powder.

[0017] d. Calcination treatment: The dried powder from step c is heated to 600-700°C in air at a rate of 2-3°C / min and held for 1-2 hours to obtain the rare earth oxide modified yttrium oxide stabilized zirconium oxide composite powder.

[0018] In step c, the spraying pressure is 0.15-0.25 MPa, and the spraying rate is 5-10 mL / min; the amount of nitrate ethanol solution used is such that the total mass of Gd2O3 and Y2O3 in the loaded yttrium-stabilized zirconia powder reaches 1.5-2.5% of the total mass of the yttrium-stabilized zirconia powder.

[0019] In the functional composite top layer, the composition of the niobium-sammarium co-doped yttrium oxide stabilized zirconium oxide matrix, based on oxides, is that the molar ratio of ZrO2:Y2O3:Nb2O5:Sm2O3 is (90-92.5):(6.5-7.5):(1-2):(0.5-1).

[0020] The functional composite top layer is obtained by processing composite spraying powder. The preparation method of the composite spraying powder of the functional composite top layer includes the following steps: mixing alumina particles with an amorphous silicon oxide layer on the surface with the niobium samarium co-doped yttrium stabilized zirconium oxide matrix powder at a mass ratio of 20:75-85 for 2-3 hours to obtain a composite spraying powder with uniform composition.

[0021] The method for preparing alumina particles with an amorphous silicon oxide layer on the surface of the composite spray powder includes the following steps: α-alumina powder is loaded into a fluidized bed reactor and preheated to 400-450°C; liquid hexamethyldisiloxane precursor is placed in an evaporator and heated to 70-85°C, and nitrogen gas with a flow rate of 300-500 mL / min is used as a carrier gas to carry the hexamethyldisiloxane vapor into the reactor; at 400-450°C, the deposition reaction is carried out for 45-90 minutes to chemically vapor-deposit an amorphous silicon oxide coating layer on the surface of the alumina particles, the coating layer having a thickness of 15-40 nanometers; after the reaction is completed, the product is cooled to room temperature under nitrogen protection to obtain the alumina particles with an amorphous silicon oxide layer on the surface.

[0022] The preparation method of the niobium-samarium co-doped yttrium oxide stabilized zirconium oxide matrix powder in the composite spraying powder includes the following steps:

[0023] I. Preparation of coprecipitation raw material solution: Zirconium oxychloride, yttrium nitrate, niobium ammonium oxalate and samarium nitrate are used as raw materials, dissolved in deionized water to prepare a coprecipitation raw material solution with a total cation concentration of 0.5-1.0 mol / L;

[0024] II. Coprecipitation reaction: At 25-35°C, the coprecipitation raw material solution from step I is uniformly added to an ammonia solution with a concentration of 4-6 mol / L within 30-45 minutes, maintaining the final pH value of the reaction system at 9.5-10.5 to generate a coprecipitate;

[0025] III. Post-treatment and secondary drying: The coprecipitate is filtered, washed alternately with water and anhydrous ethanol, and then dried at 90-110°C for 18-24 hours to obtain mixed hydroxide precursor powder.

[0026] IV. Calcination and powder processing: The mixed hydroxide precursor powder is heated to 850-950°C in air at a rate of 3-5°C / min and held for 3-4 hours to obtain niobium-sammarium co-doped yttrium-stabilized zirconia solid solution powder; the solid solution powder is dry ball-milled for 4-6 hours and then passed through a 400-mesh sieve to obtain the niobium-sammarium co-doped yttrium-stabilized zirconia matrix powder.

[0027] The metal bonding layer is NiCoCrAlY alloy spray powder.

[0028] A method for preparing a thermal barrier coating resistant to CMAS corrosion containing vertical cracks, the method comprising the following steps:

[0029] Step 1: Deposit a metal bonding layer. After surface sandblasting and cleaning of the substrate, a high-speed oxygen fuel spraying process is used to deposit NiCoCrAlYHfSi alloy powder on the substrate to form a metal bonding layer.

[0030] Step 2: Deposit a strain buffer intermediate layer. Using rare earth oxide-modified yttrium oxide-stabilized zirconia composite powder as raw material, an atmospheric plasma spraying process is used to deposit a strain buffer intermediate layer on the metal bonding layer. The rare earth oxide-modified yttrium oxide-stabilized zirconia composite powder reacts in a plasma flame to generate rare earth aluminate flakes in situ.

[0031] Step 3: Deposit the functional composite top layer. Using composite spray powder as raw material, an atmospheric plasma spraying process is used to deposit the functional composite top layer on the strain buffer intermediate layer.

[0032] Step 4: Post-processing to induce vertical cracks. The product obtained in step 3 is subjected to vacuum high-temperature treatment followed by ultrasonic-assisted rapid cooling to obtain a CMAS corrosion-resistant thermal barrier coating with a synergistic reinforcement structure.

[0033] In the first step, the process parameters for high-speed oxygen fuel spraying are as follows: the fuel is propane, the oxygen flow rate is 750-850 SLPM, the propane flow rate is 180-220 SLPM, the spraying distance is 320-350 mm, and the powder feeding rate is 45-55 g / min.

[0034] In the second step, the process parameters for atmospheric plasma spraying are as follows: the main gas is argon, with a flow rate of 38-42 SLPM; the auxiliary gas is hydrogen, with a flow rate of 10-14 SLPM; the spraying current is 520-560 A; the spraying distance is 105-115 mm; and the spray gun moving speed is 450-550 mm / s.

[0035] In the third step, the process parameters for atmospheric plasma spraying are as follows: the main gas is argon, with a flow rate of 42-46 SLPM; no auxiliary gas hydrogen is used; the spraying current is 440-470 A; the spraying distance is 135-145 mm; and the powder feeding rate is 22-28 g / min.

[0036] In the fourth step, the process parameters for the vacuum high-temperature treatment are: at a pressure below 5 × 10⁻⁶. -3 Under the condition of Pa, heat to 1020-1080℃ at a rate of 8-12℃ / min, hold for 1.5-2.5 hours, and cool to 500℃;

[0037] In the fourth step, the process parameters for the ultrasonic-assisted rapid cooling treatment are as follows: the product after vacuum high-temperature treatment is immersed in dimethyl silicone oil at a temperature of -10 to 0°C, while simultaneously applying an ultrasonically assisted rapid cooling treatment with a frequency of 25-35 kHz and a power density of 0.8-1.2 W / cm². 2 Ultrasonic quenching for 60-90 seconds.

[0038] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows:

[0039] 1. This invention employs a combination of vacuum high-temperature treatment and ultrasonic-assisted rapid cooling to construct vertical cracks. The vacuum high-temperature treatment first provides a high-temperature relaxation environment for the coating, helping to release residual stress accumulated during spraying and promoting interdiffusion and bonding strengthening between layers, particularly between the metal bonding layer and the strain-buffered intermediate layer. The subsequent ultrasonic-assisted rapid cooling process rapidly immerses the coating from a high-temperature environment into a low-temperature medium and applies ultrasound, generating intense and more directional thermal stress. The ultrasonic field may induce cavitation and enhanced convection in the cooling medium, which not only increases the intensity of cooling but may also guide a more uniform release of thermal stress within the coating, thus tending to induce vertical cracks with more controllable density and depth in the ceramic layer. These cracks penetrate the functional composite top layer from top to bottom and terminate within the strain-buffered intermediate layer, effectively segmenting the ceramic layer to release thermal cycling stress. Furthermore, the bottom layer design prevents the cracks from directly extending to the metal bonding layer interface, thereby improving strain tolerance while maintaining the overall stability of the coating system.

[0040] 2. The strain buffer interlayer of the present invention is obtained by processing yttrium oxide-stabilized zirconia composite powder modified with rare earth oxides. When the composite powder is melted and deposited in a high-temperature flame, the rare earth oxides loaded on its surface react with the zirconia matrix to generate fine rare earth aluminate lamellae in situ. These lamellae are dispersed in the yttrium oxide-stabilized zirconia matrix and play multiple roles. As second-phase particles, they can hinder the direct propagation of cracks, forcing crack tips to deflect or bifurcate, thereby consuming more fracture energy and improving the toughness of the interlayer. These lamellae structures growing parallel to the coating surface can become effective crack propagation barriers when encountering vertical cracks propagating from the functional composite top layer. They can change the direction of crack propagation or stop cracking, thereby limiting the depth of vertical cracks within the interlayer and preventing them from further penetrating and damaging the bonding of the metal binder, thus achieving active management of the crack propagation path.

[0041] 3. The functional composite top layer of this invention can enhance interfacial bonding and corrosion protection capabilities. This layer uses alumina particles coated with an amorphous silicon oxide layer, which are composited with yttrium-stabilized zirconia matrix powder co-doped with niobium and samarium. Under the high temperature of plasma spraying, the amorphous silicon oxide layer on the surface of the alumina particles can react with the molten co-doped yttrium-stabilized zirconia matrix, forming a chemically bonded transition layer at the interface. This reaction transforms the bonding between the two phases from a traditional mechanical bond to a strong and tough metallurgical bond, greatly enhancing the interfacial strength. At the same time, the co-doping of niobium and samarium into the zirconia lattice can regulate the thermophysical properties and chemical stability of the matrix. This strong interfacial bonding allows the corrosion-resistant alumina phase to be firmly embedded in the matrix, making it less prone to detachment under thermal stress. Furthermore, the dense chemically bonded interface effectively hinders the rapid penetration of molten CMAS along the particle / matrix interface, thereby improving the long-term protective capability and structural integrity of the coating in corrosive environments.

[0042] 4. The coating system of this invention exhibits synergistic effects across multiple scales. At the nanoscale, there is interfacial reaction of the amorphous silicon oxide layer and doping modification by rare earth elements; at the microscale, there is in-situ generated lamellar crystals that deflect and pin cracks, as well as the construction of a controlled vertical crack network; at the macroscale, a sandwich structure is formed with a gradient transition in thermophysical properties between the metal bonding layer, the strain buffer intermediate layer, and the functional composite top layer. Each layer performs its specific function while cooperating with each other: the functional composite top layer provides strong and tough corrosion protection, the strain buffer intermediate layer achieves toughening and crack management, the universal metal bonding layer ensures reliable bonding with the substrate, and the unified spraying and post-treatment process integrates them into a single unit. This synergistic effect enables the coating to more effectively cope with both thermomechanical stress failure caused by thermal cycling and environmental corrosion failure caused by CMAS, exhibiting more reliable and durable comprehensive performance than existing single-functional coatings or simple laminated structures under complex and harsh high-temperature service conditions. Detailed Implementation

[0043] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] In the specific embodiments of this application, the sources of various main raw materials are briefly described as follows:

[0045] NiCoCrAlY alloy coating powder: Sulzer Metco's AMDRY 997 powder.

[0046] Gadolinium nitrate hexahydrate: Shandong Desheng New Materials Co., Ltd. CAS No.: 10031-53-5

[0047] Yttrium nitrate hexahydrate: Sigma-Aldrich (Shanghai) Trading Co., Ltd. CAS No.: 13494-98-9

[0048] Samarium nitrate hexahydrate: Shandong Desheng New Materials Co., Ltd. CAS No.: 13759-83-6

[0049] Ammonium niobate oxalate: Shaanxi Didu Pharmaceutical Chemical Co., Ltd. CAS No.: 13811-70-4

[0050] Zirconium oxychloride: Shandong Desheng New Materials Co., Ltd. CAS No.: 7699-43-6

[0051] Hexamethyldisiloxane: Huangshan Kebei New Material Technology Co., Ltd. CAS No.: 107-46-0

[0052] Anhydrous ethanol: Sinopharm Chemical Reagent Co., Ltd. CAS No.: 64-17-5

[0053] Ammonia water: Qingdao Hongdie New Materials Co., Ltd.

[0054] Dimethyl silicone oil: Industrial coolant grade from Sangon Biotech (Shanghai) Co., Ltd., viscosity 50–100 cSt

[0055] α-Alumina Powder: Saint-Gobain (China) Investment Co., Ltd. Specification: High-purity α-phase

[0056] Yttrium-stabilized zirconia powder: Saint-Gobain (China) Investment Co., Ltd. Model: CY3Z.

[0057] The technical solution of this application is as follows:

[0058] A thermal barrier coating resistant to CMAS corrosion containing vertical cracks, the coating comprising, from the substrate outwards, a metal bonding layer, a strain buffer intermediate layer and a functional composite top layer, wherein the strain buffer intermediate layer is composed of yttrium-stabilized zirconium oxide containing in-situ generated rare earth aluminate lamellar crystals.

[0059] The functional composite top layer is composed of alumina particles coated with an amorphous silicon oxide layer and a niobium-sammarium co-doped yttrium-stabilized zirconium oxide matrix.

[0060] The coating contains vertical cracks that penetrate the functional composite top layer and terminate in the strain-buffered intermediate layer.

[0061] The thickness of the metal bonding layer is 80-150 micrometers; the thickness of the strain buffer intermediate layer is 180-250 micrometers; the thickness of the functional composite top layer is 200-280 micrometers; and the linear density of the vertical cracks on the surface of the functional composite top layer is 3.0-4.0 cracks / mm.

[0062] The strain buffer intermediate layer is obtained by processing yttrium oxide-stabilized zirconia composite powder modified with rare earth oxides. The preparation method of the rare earth oxide-modified yttrium oxide-stabilized zirconia composite powder includes the following steps:

[0063] a. Weigh out yttrium oxide stabilized zirconium oxide powder, wherein the molar fraction of yttrium oxide is 7-8% and the powder particle size D50 is 15-25 micrometers;

[0064] b. Preparation of nitrate solution: Dissolve gadolinium nitrate hexahydrate and yttrium nitrate hexahydrate in anhydrous ethanol at a molar ratio of Gd to Y of 1:1 to 2:1 to prepare a nitrate ethanol solution with a total metal ion concentration of 0.2-0.4 mol / L.

[0065] c. Solution impregnation and primary drying: The yttrium-stabilized zirconia powder from step a is placed in a fluidized bed. At 40-60°C, the nitrate ethanol solution from step b is loaded onto the surface of the yttrium-stabilized zirconia powder by atomization spraying. Then, it is dried at 80-100°C for 10-14 hours to obtain a primary dried powder.

[0066] d. Calcination treatment: The dried powder from step c is heated to 600-700°C in air at a rate of 2-3°C / min and held for 1-2 hours to obtain the rare earth oxide modified yttrium oxide stabilized zirconium oxide composite powder.

[0067] In step c, the spraying pressure is 0.15-0.25 MPa, and the spraying rate is 5-10 mL / min; the amount of nitrate ethanol solution used is such that the total mass of Gd2O3 and Y2O3 in the loaded yttrium-stabilized zirconia powder reaches 1.5-2.5% of the total mass of the yttrium-stabilized zirconia powder.

[0068] In the functional composite top layer, the composition of the niobium-sammarium co-doped yttrium oxide stabilized zirconium oxide matrix, based on oxides, is that the molar ratio of ZrO2:Y2O3:Nb2O5:Sm2O3 is (90-92.5):(6.5-7.5):(1-2):(0.5-1).

[0069] The functional composite top layer is obtained by processing composite spraying powder. The preparation method of the composite spraying powder of the functional composite top layer includes the following steps: mixing alumina particles with an amorphous silicon oxide layer on the surface with the niobium samarium co-doped yttrium stabilized zirconium oxide matrix powder at a mass ratio of 20:75-85 for 2-3 hours to obtain a composite spraying powder with uniform composition.

[0070] The method for preparing alumina particles with an amorphous silicon oxide layer on the surface of the composite spray powder includes the following steps: α-alumina powder is loaded into a fluidized bed reactor and preheated to 400-450°C; liquid hexamethyldisiloxane precursor is placed in an evaporator and heated to 70-85°C, and nitrogen gas with a flow rate of 300-500 mL / min is used as a carrier gas to carry the hexamethyldisiloxane vapor into the reactor; at 400-450°C, the deposition reaction is carried out for 45-90 minutes to chemically vapor-deposit an amorphous silicon oxide coating layer on the surface of the alumina particles, the coating layer having a thickness of 15-40 nanometers; after the reaction is completed, the product is cooled to room temperature under nitrogen protection to obtain the alumina particles with an amorphous silicon oxide layer on the surface.

[0071] The preparation method of the niobium-samarium co-doped yttrium oxide stabilized zirconium oxide matrix powder in the composite spraying powder includes the following steps:

[0072] I. Preparation of coprecipitation raw material solution: Zirconium oxychloride, yttrium nitrate, niobium ammonium oxalate and samarium nitrate are used as raw materials, dissolved in deionized water to prepare a coprecipitation raw material solution with a total cation concentration of 0.5-1.0 mol / L;

[0073] II. Coprecipitation reaction: At 25-35°C, the coprecipitation raw material solution from step I is uniformly added to an ammonia solution with a concentration of 4-6 mol / L within 30-45 minutes, maintaining the final pH value of the reaction system at 9.5-10.5 to generate a coprecipitate;

[0074] III. Post-treatment and secondary drying: The coprecipitate is filtered, washed alternately with water and anhydrous ethanol, and then dried at 90-110°C for 18-24 hours to obtain mixed hydroxide precursor powder.

[0075] IV. Calcination and powder processing: The mixed hydroxide precursor powder is heated to 850-950°C in air at a rate of 3-5°C / min and held for 3-4 hours to obtain niobium-sammarium co-doped yttrium-stabilized zirconia solid solution powder; the solid solution powder is dry ball-milled for 4-6 hours and then passed through a 400-mesh sieve to obtain the niobium-sammarium co-doped yttrium-stabilized zirconia matrix powder.

[0076] The metal bonding layer is NiCoCrAlY alloy spray powder.

[0077] A method for preparing a thermal barrier coating resistant to CMAS corrosion containing vertical cracks, the method comprising the following steps:

[0078] Step 1: Deposit a metal bonding layer. After surface sandblasting and cleaning of the substrate, a high-speed oxygen fuel spraying process is used to deposit NiCoCrAlYHfSi alloy powder on the substrate to form a metal bonding layer.

[0079] Step 2: Deposit a strain buffer intermediate layer. Using rare earth oxide-modified yttrium oxide-stabilized zirconia composite powder as raw material, an atmospheric plasma spraying process is used to deposit a strain buffer intermediate layer on the metal bonding layer. The rare earth oxide-modified yttrium oxide-stabilized zirconia composite powder reacts in a plasma flame to generate rare earth aluminate flakes in situ.

[0080] Step 3: Deposit the functional composite top layer. Using composite spray powder as raw material, an atmospheric plasma spraying process is used to deposit the functional composite top layer on the strain buffer intermediate layer.

[0081] Step 4: Post-processing to induce vertical cracks. The product obtained in step 3 is subjected to vacuum high-temperature treatment followed by ultrasonic-assisted rapid cooling to obtain a CMAS corrosion-resistant thermal barrier coating with a synergistic reinforcement structure.

[0082] In the first step, the process parameters for high-speed oxygen fuel spraying are as follows: the fuel is propane, the oxygen flow rate is 750-850 SLPM, the propane flow rate is 180-220 SLPM, the spraying distance is 320-350 mm, and the powder feeding rate is 45-55 g / min.

[0083] In the second step, the process parameters for atmospheric plasma spraying are as follows: the main gas is argon, with a flow rate of 38-42 SLPM; the auxiliary gas is hydrogen, with a flow rate of 10-14 SLPM; the spraying current is 520-560 A; the spraying distance is 105-115 mm; and the spray gun moving speed is 450-550 mm / s.

[0084] In the third step, the process parameters for atmospheric plasma spraying are as follows: the main gas is argon, with a flow rate of 42-46 SLPM; no auxiliary gas hydrogen is used; the spraying current is 440-470 A; the spraying distance is 135-145 mm; and the powder feeding rate is 22-28 g / min.

[0085] In the fourth step, the process parameters for the vacuum high-temperature treatment are: at a pressure below 5 × 10⁻⁶. -3 Under the condition of Pa, heat to 1020-1080℃ at a rate of 8-12℃ / min, hold for 1.5-2.5 hours, and cool to 500℃;

[0086] In the fourth step, the process parameters for the ultrasonic-assisted rapid cooling treatment are as follows: the product after vacuum high-temperature treatment is immersed in dimethyl silicone oil at a temperature of -10 to 0°C, while simultaneously applying an ultrasonically assisted rapid cooling treatment with a frequency of 25-35 kHz and a power density of 0.8-1.2 W / cm². 2 Ultrasonic quenching for 60-90 seconds.

[0087] To address the challenge of controllable vertical crack formation, this application proposes a step-by-step post-processing strategy: first, vacuum high-temperature treatment, followed by ultrasonic-assisted rapid cooling. Conventional process cracks form directly during spray cooling, driven by the rapid solidification and shrinkage of sprayed particles and random internal stresses generated by interlayer thermal mismatch, resulting in uncontrollable crack morphology. The method in this application first provides a condition for stress relaxation and interfacial atomic interdiffusion within the coating through a high-temperature holding process in a vacuum environment. This helps homogenize internal stress and strengthen interlayer bonding, establishing a more uniform stress background for subsequent controllable cracking. The subsequent ultrasonic-assisted rapid cooling is a crucial step, rapidly immersing the coating from high temperature into a low-temperature medium and applying ultrasound. Its beneficial effect is the generation of intense and more directional cooling stress. The cavitation effect and forced convection induced by the ultrasonic field in the cooling medium make the cooling process not only intense but also more uniform, guiding thermal stress primarily to be released along a direction perpendicular to the coating surface. This controlled stress state causes cracks to preferentially initiate and propagate within the ceramic layer along the direction of heat flow, i.e., perpendicular to the surface. By adjusting the temperature, time, and ultrasonic parameters of the process, the density and depth of the induced vertical cracks can be effectively controlled, thereby obtaining a crack network that can both divide the ceramic layer to release thermal stress and has a stable morphology.

[0088] After achieving the controlled introduction of vertical cracks, the next challenge is preventing these cracks from propagating unchecked under thermal cycling loads, particularly towards the metal bond layer interface, which could lead to overall coating peeling. This necessitates the presence of effective crack deflection and arrest structures within the coating, especially along the expected propagation path of vertical cracks. In the design of the strain-buffered intermediate layer, this application utilizes yttrium oxide-stabilized zirconia composite powder modified with rare-earth oxides and leverages the high-temperature characteristics of plasma spraying to achieve in-situ generation of rare-earth aluminate lamellars. The beneficial effect is that when the powder containing rare-earth oxides is melt-deposited in the flame, the rare-earth elements react with zirconia and aluminum introduced from the environment or raw materials, generating fine rare-earth aluminate lamellars with a crystallographic orientation tending to be parallel to the coating surface. These dispersed lamellars play a crucial role in microscopic toughening. When the tip of a vertical crack extending from the functional composite top layer encounters these lamellar crystals, the crack propagation path changes, such as bypassing, bifurcating, or being pinned, thereby consuming a large amount of fracture energy and significantly improving the fracture toughness of the interlayer. More importantly, these lamellar crystals parallel to the interface form multiple microscopic barriers that effectively prevent vertical cracks from penetrating further downward, limiting their depth within the strain-buffered interlayer. This protects the integrity of the metal bond layer interface and achieves active crack management.

[0089] Having solved the problems of macroscopic crack control and microscopic toughening of the coating, it is necessary to further overcome the fundamental defect of weak interfacial bonding between the corrosion-resistant phase and the matrix in the functional composite top layer. In existing technologies, the simple physical mixing of alumina particles and the yttrium-stabilized zirconia matrix results in only mechanical bonding, leading to low interfacial strength. This application pre-modifies the surface of the alumina particles by coating them with an amorphous silicon oxide layer via chemical vapor deposition, while using niobium- and samarium-doped yttrium-stabilized zirconia as the matrix material. Under the high temperature of plasma spraying, the amorphous silicon oxide layer on the surface of the alumina particles reacts with the molten niobium- and samarium-doped yttrium-stabilized zirconia matrix, generating a silicate-based compound transition layer in situ at the interface. This process elevates the bonding between the two phases from physical adsorption or mechanical interlocking to chemical metallurgical bonding, significantly enhancing the interfacial bonding strength and high-temperature stability. Meanwhile, the co-doping of niobium and samarium into the zirconium oxide lattice stabilizes the crystal structure, regulates oxygen ion conductivity, and optimizes thermal expansion behavior, resulting in better physicochemical compatibility between the matrix and the modified alumina particles. This strong interfacial bonding ensures that the corrosion-resistant alumina phase is firmly embedded in the matrix, resisting debonding under thermal stress. Furthermore, the dense reaction interface effectively blocks the penetration of molten CMAS, fundamentally improving the long-term corrosion resistance of the coating.

[0090] The technical solution of this application embodies a multi-scale synergistic approach, from macroscopic structural design to microscopic interface control. At the macroscopic scale, a gradient structure of a metallic bonding layer, a strain-buffered intermediate layer, and a functional composite top layer achieves a smooth transition of thermal stress. At the micrometer scale, a controlled post-processing technique introduces a vertical crack network to release stress, and in-situ self-generated lamellar crystals guide and arrest cracks. At the nanometer scale, strong metallurgical bonding is achieved through interface engineering involving particle surface modification and matrix doping. The functions of each layer and at each scale are not simply superimposed, but rather mutually complementary and reinforcing. For example, the functional composite top layer with strong interfacial bonding provides a stable corrosion-protective shell for the entire coating, while the underlying strain-buffered intermediate layer, which provides toughening and crack control, ensures that the top layer will not fail even when stress-release cracks occur. This synergistic effect enables the coating system to simultaneously and effectively address thermomechanical stress failure caused by high-temperature thermal cycling and chemical environmental failure caused by CMAS corrosion, achieving a balance and improvement in performance. This provides a feasible solution for the design of thermal barrier coatings operating in more demanding environments.

[0091] This application solves the performance contradiction between thermal shock resistance and CMAS corrosion resistance of thermal barrier coatings by synergistically controlling the macroscopic crack network, micron-scale toughening structure and nanoscale toughening interface of the coating.

[0092] The present invention will be described in detail below through examples and comparative examples, but the scope of protection of the present invention is not limited to these examples. Unless otherwise specified, the chemical reagents and raw materials used in the following examples and comparative examples are all conventional commercially available products.

[0093] Example 1

[0094] This example demonstrates the preparation of a thermal barrier coating with vertical cracks that is resistant to CMAS corrosion.

[0095] First, the raw material powder for the strain buffer intermediate layer was prepared. Yttrium-stabilized zirconia powder with a yttrium oxide molar fraction of 8% and a particle size D50 of 25 μm was weighed. A nitrate-ethanol solution was prepared by dissolving gadolinium nitrate hexahydrate and yttrium nitrate hexahydrate in anhydrous ethanol at a Gd:Y molar ratio of 2:1, resulting in a total metal ion concentration of 0.4 mol / L. The yttrium-stabilized zirconia powder was placed in a fluidized bed, and the nitrate-ethanol solution was atomized and sprayed onto the powder surface at 60°C. The spraying pressure was 0.25 MPa, and the spraying rate was 10 mL / min. The amount of solution used was such that the total mass of Gd₂O₃ and Y₂O₃ in the loaded powder reached 2.5% of the total powder mass. The powder was then dried at 100°C for 14 hours to obtain a single-dry powder. The powder was heated to 700°C in air at a rate of 3°C / min and held for 2 hours to obtain rare earth oxide-modified yttrium oxide-stabilized zirconium oxide composite powder.

[0096] Secondly, the raw materials for preparing the functional composite top layer are as follows. The alumina particles with an amorphous silicon oxide layer coated on the surface required for the functional composite top layer are prepared through the following steps: α-alumina powder is loaded into a fluidized bed reactor and preheated to 450°C. Liquid hexamethyldisiloxane precursor is evaporated at 85°C, and nitrogen gas at a flow rate of 500 mL / min is used as a carrier gas to carry the vapor into the reactor. Deposition is carried out at 450°C for 90 minutes to coat the alumina particles with an amorphous silicon oxide layer with a thickness of 40 nm. After cooling, the coated particles are obtained. The niobium-sammarium co-doped yttrium-stabilized zirconium oxide matrix powder required for the functional composite top layer is prepared by a co-precipitation method: using zirconium oxychloride, yttrium nitrate, niobium ammonium oxalate, and samarium nitrate as raw materials, a solution with a total cation concentration of 1.0 mol / L is prepared, wherein the molar ratio of ZrO2, Y2O3, Nb2O5, and Sm2O3 is 92.5:6.5:2:0.5. At 35°C, the solution was added dropwise to 6 mol / L ammonia water over 45 minutes, with the final pH controlled at 10.5. The precipitate was filtered, washed alternately with water and anhydrous ethanol, and dried at 110°C for 24 hours. The resulting precursor was heated to 950°C in air at a rate of 5°C / min, held at that temperature for 4 hours, then ball-milled for 6 hours and passed through a 400-mesh sieve to obtain the matrix powder. Finally, silica-coated alumina particles were mixed with the matrix powder at a mass ratio of 20:80 for 3 hours to obtain a composite spray powder for the functional composite top layer.

[0097] Next, coating deposition was performed. A nickel-based superalloy was selected as the substrate. After sandblasting and cleaning, a high-speed oxygen fuel spraying process was used to deposit the metal bonding layer. Commercially available spraying powder with a composition of NiCoCrAlY was used, with the following process parameters: propane fuel, oxygen flow rate 850 SLPM, propane flow rate 220 SLPM, spraying distance 350 mm, and powder feed rate 55 g / min. Then, using the aforementioned self-made rare-earth oxide modified zirconia composite powder, an atmospheric plasma spraying process was used to deposit a strain buffer intermediate layer. The process parameters were: main gas argon flow rate 42 SLPM, auxiliary gas hydrogen flow rate 14 SLPM, spraying current 560 A, spraying distance 115 mm, and spray gun movement speed 550 mm / s. Finally, using the aforementioned self-made composite spraying powder, an atmospheric plasma spraying process was used to deposit the functional composite top layer. The process parameters are as follows: argon main gas flow rate 46 SLPM, no hydrogen auxiliary gas used, spraying current 470A, spraying distance 145 mm, and powder feeding rate 28 g / min.

[0098] Finally, post-treatment is performed to induce vertical cracks. The sprayed coating is placed in a vacuum furnace at a pressure below 5 × 10⁻⁻⁻⁻⁶. 3Under the condition of Pa, the sample was heated to 1080°C at a rate of 12°C / min, held at that temperature for 2.5 hours, and then cooled in the furnace to below 500°C. Subsequently, the coated sample was rapidly immersed in dimethyl silicone oil at 0°C, while applying a power density of 1.2 W / cm² at a frequency of 35 kHz. 2 The target coating is obtained by ultrasonic quenching for 90 seconds. The thicknesses of the metal bonding layer, strain buffer intermediate layer, and functional composite top layer are measured to be approximately 150 micrometers, 250 micrometers, and 280 micrometers, respectively.

[0099] Example 2

[0100] In this embodiment, the similarities to those in Embodiment 1 will not be repeated, and the differences are as follows:

[0101] First, the raw material powder for the strain buffer intermediate layer was prepared. Yttrium oxide-stabilized zirconium oxide powder with a yttrium oxide molar fraction of 7% and a particle size D50 of 15 μm was weighed. A nitrate-ethanol solution was prepared with a Gd to Y molar ratio of 1:1 and a total metal ion concentration of 0.2 mol / L. Fluidized bed impregnation and drying were performed at 40°C, a spraying pressure of 0.15 MPa, and a spraying rate of 5 mL / min. The solution volume was adjusted so that the total mass ratio of Gd₂O₃ to Y₂O₃ was 1.5%. Drying was carried out at 80°C for 10 hours. Calcination was then performed by heating to 600°C at a rate of 2°C / min and holding at that temperature for 1 hour.

[0102] Secondly, the raw materials for the functional composite top layer were prepared. In the preparation of alumina particles coated with a silica layer, the preheating temperature was 400°C, the hexamethyldisiloxane evaporation temperature was 70°C, the nitrogen flow rate was 300 mL / min, the deposition temperature was 400°C, the deposition time was 45 minutes, and the coating thickness was 15 nm. In the preparation of the niobium-sammarium co-doped matrix powder, the total cation concentration of the co-precipitated raw material solution was 0.5 mol / L, with an oxide molar ratio of 90:7.5:1:1. The reaction temperature was 25°C, the dropping time was 30 minutes, the ammonia concentration was 4 mol / L, and the final pH was 9.5. The precipitation drying conditions were 18 hours at 90°C. The calcination regime involved heating to 850°C at a rate of 3°C / min, holding at that temperature for 3 hours, and ball milling for 4 hours. During composite preparation, the mass ratio of coated alumina particles to matrix powder remained 20:80, and the mixing time was 2 hours.

[0103] Then, coating deposition was performed. The parameters for the high-speed oxygen fuel spraying metal binder layer were: oxygen flow rate 750 SLPM, propane flow rate 180 SLPM, spraying distance 320 mm, and powder feed rate 45 g / min. The parameters for the atmospheric plasma spraying strain buffer intermediate layer were: argon flow rate 38 SLPM, hydrogen flow rate 10 SLPM, spraying current 520 A, spraying distance 105 mm, and spray gun movement speed 450 mm / s. The parameters for the atmospheric plasma spraying functional composite top layer were: argon flow rate 42 SLPM, spraying current 440 A, spraying distance 135 mm, and powder feed rate 22 g / min.

[0104] Finally, post-treatment was used to induce cracking. Vacuum high-temperature treatment was performed, heating to 1020°C at a rate of 8°C / min and holding for 1.5 hours. During ultrasonic-assisted rapid cooling, the silicone oil temperature was -10°C, the ultrasonic frequency was 25 kHz, and the power density was 0.8 W / cm³. 2 The quenching time was 60 seconds. The thicknesses of the resulting coating layers were approximately 80 micrometers, 180 micrometers, and 200 micrometers, respectively.

[0105] Example 3

[0106] In this embodiment, the similarities to those in Embodiment 1 will not be repeated, and the differences are as follows:

[0107] First, the raw material powder for the strain buffer intermediate layer was prepared. Yttrium-stabilized zirconia powder with a yttrium oxide molar fraction of 7.5% and a particle size D50 of 20 μm was weighed. A nitrate-ethanol solution was prepared with a Gd to Y molar ratio of 1.5:1 and a total metal ion concentration of 0.3 mol / L. Fluidized bed impregnation and drying were performed at 50°C, a spraying pressure of 0.20 MPa, and a spraying rate of 7.5 mL / min. The solution volume was adjusted so that the total mass ratio of Gd₂O₃ to Y₂O₃ was 2.0%. Drying was carried out at 90°C for 12 hours. Calcination was then performed, with the temperature increased to 650°C at a rate of 2.5°C / min and held for 1.5 hours.

[0108] Secondly, the raw materials for the functional composite top layer were prepared. In the preparation of alumina particles coated with a silica layer, the preheating temperature was 425°C, the hexamethyldisiloxane evaporation temperature was 77.5°C, the nitrogen flow rate was 400 mL / min, the deposition temperature was 425°C, the deposition time was 67.5 minutes, and the coating thickness was 27.5 nm. In the preparation of the niobium-samarium co-doped matrix powder, the total cation concentration of the co-precipitated raw material solution was 0.75 mol / L, with an oxide molar ratio of 91.25:7.0:1.5:0.75. The reaction temperature was 30°C, the dropping time was 37.5 minutes, the ammonia concentration was 5 mol / L, and the final pH was 10.0. The precipitation drying conditions were 100°C for 21 hours. The calcination regime was a heating rate of 4°C / min to 900°C, a holding time of 3.5 hours, and ball milling for 5 hours. During composite preparation, the mass ratio of coated alumina particles to matrix powder remained 20:80, and the mixing time was 2.5 hours.

[0109] Then, coating deposition was performed. The parameters for the high-speed oxygen fuel spraying metal binder layer were: oxygen flow rate 800 SLPM, propane flow rate 200 SLPM, spraying distance 335 mm, and powder feed rate 50 g / min. The parameters for the atmospheric plasma spraying strain buffer intermediate layer were: argon flow rate 40 SLPM, hydrogen flow rate 12 SLPM, spraying current 540 A, spraying distance 110 mm, and spray gun movement speed 500 mm / s. The parameters for the atmospheric plasma spraying functional composite top layer were: argon flow rate 44 SLPM, spraying current 455 A, spraying distance 140 mm, and powder feed rate 25 g / min.

[0110] Finally, post-treatment was used to induce cracking. Vacuum high-temperature treatment was applied, heating to 1050°C at a rate of 10°C / min and holding for 2 hours. During ultrasonic-assisted rapid cooling, the silicone oil temperature was -5°C, the ultrasonic frequency was 30 kHz, and the power density was 1.0 W / cm³. 2 The quenching time was 75 seconds. The thicknesses of the resulting coating layers were approximately 115 micrometers, 215 micrometers, and 240 micrometers, respectively.

[0111] Comparative Example 1

[0112] In this comparative example, the similarities with Example 1 will not be repeated, and the differences are as follows:

[0113] After the coating is deposited, instead of vacuum high-temperature treatment and ultrasonic-assisted rapid cooling, it is allowed to cool naturally to room temperature in air.

[0114] Comparative Example 2

[0115] In this comparative example, the similarities with Example 2 will not be repeated, and the differences are as follows:

[0116] When preparing the strain buffer intermediate layer, the rare earth oxide modification step was omitted. Pristine yttrium-stabilized zirconia powder with a yttrium oxide molar fraction of 7% was directly used for atmospheric plasma spraying, without nitrate solution impregnation, drying, or calcination.

[0117] Comparative Example 3

[0118] In this comparative example, the similarities with Example 3 will not be repeated, and the differences are as follows:

[0119] When preparing the composite spray powder for the functional composite top layer, use raw α-alumina particles without an amorphous silicon oxide layer to replace alumina particles with an amorphous silicon oxide layer on the surface.

[0120] Comparative Example 4

[0121] In this comparative example, the similarities with Example 1 will not be repeated, and the differences are as follows:

[0122] When preparing the matrix powder for the functional composite top layer, ordinary yttrium-stabilized zirconia powder without niobium and samarium co-doping is used, with a yttrium molar fraction of 8%, to replace the niobium-samarium co-doped yttrium-stabilized zirconia matrix powder.

[0123] Comparative Example 5

[0124] This comparative example simulates a simplified conventional process. The coating structure consists of only a metal bonding layer plus a single ceramic layer. The ceramic layer is deposited using atmospheric plasma spraying, with the raw material being a simple physical mixture of yttrium-stabilized zirconium oxide powder (8% yttrium oxide molar fraction) and α-alumina powder at a mass ratio of 80:20, and a mixing time of 2 hours. The spraying process parameters are the same as those for the functional composite top layer in Example 1. After deposition, no vacuum high-temperature or ultrasonic-assisted quenching is performed; cooling is only performed in air.

[0125] Performance Test Results and Analysis

[0126] To evaluate the coating performance, the following tests were performed on the coating samples prepared in all examples and comparative examples:

[0127] 1. Thermal shock cycle test: The coating sample is kept in a box furnace at 1100℃ for 10 minutes, and then quickly taken out and quenched in room temperature water. The number of cycles when obvious peeling occurs on the coating surface and the area is greater than 5% is recorded as the thermal shock life.

[0128] 2. CMAS Corrosion Test: A layer of CMAS molten glass powder (composition: 33CaO-9MgO-13AlO1.5-45SiO2, mol%) was uniformly coated on the surface and statically oxidized at 1200℃ for 50 hours. After cooling, a cross-sectional sample of the coating was prepared, and the maximum penetration depth of the CMAS corrosion products was measured using a scanning electron microscope.

[0129] 3. Interface bonding strength test: Using a universal testing machine, the interface bonding strength between the ceramic layer (strain buffer intermediate layer and functional composite top layer) and the metal bonding layer was determined according to the standard tensile method.

[0130] 4. Characterization of vertical cracks: Using a metallographic microscope and image analysis software, the number of vertical cracks per unit length of the coating section was observed and counted, the linear density was calculated, and the depth of typical cracks was measured.

[0131] The test results are shown in Table 1.

[0132] As can be seen from Table 1, the overall performance of the three embodiments is significantly better than that of all comparative examples. Although there are fluctuations in performance among the embodiments, the overall performance is at an excellent and stable high level, indicating that the technical solution of the present invention can achieve the expected results within a wide range of parameters.

[0133] Specifically, Examples 1, 2, and 3 all exhibited high thermal shock lifetimes exceeding 1500 cycles, primarily attributed to the effective introduction of vertical cracks and the toughening effect of the strain-buffered intermediate layer. Vertical crack line density data showed that the crack density in all three examples was within the ideal range of 3.5-4.0 cracks / mm. These cracks were a direct result of ultrasonic-assisted rapid cooling following vacuum high-temperature treatment. Comparative Example 1, by completely omitting the post-treatment step, had almost no effective vertical cracks formed within its coating, resulting in ineffective stress release during thermal cycling and a drastic drop in thermal shock lifetime to less than 500 cycles. This conversely confirms the necessity of the post-treatment process described in this invention for constructing stress release channels. Although Comparative Example 2 also underwent post-treatment to form vertical cracks, the lack of in-situ generated rare-earth aluminate lamellars in its strain-buffered intermediate layer led to a lack of effective deflection and pinning of the cracks during propagation, resulting in a weakened toughening effect and a thermal shock lifetime of only 875 cycles, lower than the examples. Comparative Example 5, as a traditional simple structure, had very few cracks within its coating and the lowest thermal shock lifetime, further highlighting the advantages of the multi-layered synergistic design of this invention.

[0134] Table 1 Analysis of Test Results

[0135] Regarding CMAS corrosion resistance, the penetration depth of all three embodiments was controlled at around 60 micrometers, significantly lower than all comparative examples. This is mainly due to the strong interfacial bonding formed between the alumina particles coated with an amorphous silicon oxide layer and the niobium-sammarium co-doped yttrium-stabilized zirconium oxide matrix in the functional composite top layer. The test results of Comparative Example 3 provide direct evidence: when using uncoated raw alumina particles, the interface between them and the matrix is ​​weak, and the CMAS melt easily penetrates rapidly along this interface, resulting in a penetration depth as high as 105 micrometers, almost twice that of the embodiments. The results of Comparative Example 4 show that the lack of niobium and samarium co-doped matrix may result in insufficient thermophysical and chemical stability, failing to form optimal synergy with the alumina particles, also leading to a relatively large penetration depth of 92 micrometers. The simple physical hybrid structure of Comparative Example 5 has the weakest interfacial bonding and the deepest corrosion penetration depth, reaching 135 micrometers. This indicates that simply introducing alumina without improving its interfacial bonding state not only fails to effectively resist corrosion but may even deteriorate the coating performance, which is completely consistent with the problems pointed out in the background art. The corrosion depth of Comparative Examples 1 and 2 was also higher than that of the Example, which shows that even with vertical cracks or partial structures, the overall corrosion resistance will still decrease if the top layer interface is not strongly bonded or the intermediate layer structure is incomplete.

[0136] Regarding interfacial bonding strength, all three embodiments achieved a high level of over 48 MPa. This is attributed to the complete process chain: the intermediate layer formed by rare earth oxide modified powder bonded well with the metal binder layer, and the strong interfacial bonding within the top layer also contributed to the integrity of the overall structure. In contrast, Comparative Example 1 had lower bonding strength due to the lack of interfacial diffusion and strengthening resulting from vacuum high-temperature treatment. Comparative Examples 2, 3, and 4 also had correspondingly lower bonding strengths due to the absence of single factors such as intermediate layer lamellar reinforcement, strong interfacial bonding between top-layer particles and the matrix, or matrix doping optimization. The simple bilayer structure of Comparative Example 5 had the lowest interfacial bonding strength, at only 36.7 MPa.

[0137] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A thermal barrier coating resistant to CMAS corrosion containing vertical cracks, the coating comprising, from the substrate outwards, a metallic binder layer, a strain-buffered intermediate layer, and a functional composite top layer, characterized in that, The strain buffer intermediate layer is composed of yttrium-stabilized zirconium oxide containing in-situ generated rare earth aluminate lamellar crystals. The functional composite top layer is composed of alumina particles with an amorphous silicon oxide layer on the surface and a niobium-sammarium co-doped yttrium-stabilized zirconium oxide matrix; The coating contains vertical cracks that penetrate the functional composite top layer and terminate in the strain-buffered intermediate layer.

2. The thermal barrier coating with vertical cracks resistant to CMAS corrosion according to claim 1, characterized in that, The thickness of the metal bonding layer is 80-150 micrometers; the thickness of the strain buffer intermediate layer is 180-250 micrometers; the thickness of the functional composite top layer is 200-280 micrometers; and the linear density of the vertical cracks on the surface of the functional composite top layer is 3.0-4.0 cracks / mm.

3. The thermal barrier coating with vertical cracks resistant to CMAS corrosion according to claim 1, characterized in that, The strain buffer intermediate layer is obtained by processing yttrium oxide-stabilized zirconia composite powder modified with rare earth oxides. The preparation method of the rare earth oxide-modified yttrium oxide-stabilized zirconia composite powder includes the following steps: (1) Weigh out yttrium oxide stabilized zirconium oxide powder, wherein the molar fraction of yttrium oxide is 7-8% and the powder particle size D50 is 15-25 micrometers; (2) Preparation of nitrate solution: Dissolve gadolinium nitrate hexahydrate and yttrium nitrate hexahydrate in anhydrous ethanol at a molar ratio of Gd to Y of 1:1 to 2:1 to prepare a nitrate ethanol solution with a total metal ion concentration of 0.2-0.4 mol / L. (3) Solution impregnation and primary drying: The yttrium-stabilized zirconia powder from step (1) is placed in a fluidized bed, and the nitrate ethanol solution from step (2) is loaded onto the surface of the yttrium-stabilized zirconia powder by atomization spraying at 40-60°C. Then, it is dried at 80-100°C for 10-14 hours to obtain primary dried powder. (4) Calcination treatment: The dried powder from step (3) is heated to 600-700°C in air at a rate of 2-3°C / min and held for 1-2 hours to obtain the rare earth oxide modified yttrium oxide stabilized zirconium oxide composite powder. In step (3), the spraying pressure is 0.15-0.25 MPa and the spraying rate is 5-10 mL / min; the amount of nitrate ethanol solution used is such that the total mass of Gd2O3 and Y2O3 in the loaded yttrium-stabilized zirconia powder reaches 1.5-2.5% of the total mass of the yttrium-stabilized zirconia powder.

4. A thermal barrier coating with vertical cracks resistant to CMAS corrosion according to claim 1, characterized in that, In the functional composite top layer, the composition of the niobium-sammarium co-doped yttrium oxide stabilized zirconium oxide matrix, based on oxides, is that the molar ratio of ZrO2:Y2O3:Nb2O5:Sm2O3 is (90-92.5):(6.5-7.5):(1-2):(0.5-1).

5. A thermal barrier coating with vertical cracks resistant to CMAS corrosion according to claim 1, characterized in that, The functional composite top layer is obtained by processing composite spraying powder. The preparation method of the composite spraying powder of the functional composite top layer includes the following steps: mixing alumina particles with an amorphous silicon oxide layer on the surface with the niobium samarium co-doped yttrium stabilized zirconium oxide matrix powder at a mass ratio of 20:75-85 for 2-3 hours to obtain a composite spraying powder with uniform composition.

6. A thermal barrier coating with vertical cracks resistant to CMAS corrosion according to claim 5, characterized in that, The method for preparing alumina particles with an amorphous silicon oxide layer on the surface of the composite spray powder includes the following steps: α-alumina powder is loaded into a fluidized bed reactor and preheated to 400-450°C; liquid hexamethyldisiloxane precursor is placed in an evaporator and heated to 70-85°C, and nitrogen gas with a flow rate of 300-500 mL / min is used as a carrier gas to carry the hexamethyldisiloxane vapor into the reactor; at 400-450°C, the deposition reaction is carried out for 45-90 minutes to chemically vapor-deposit an amorphous silicon oxide coating layer on the surface of the alumina particles, the coating layer having a thickness of 15-40 nanometers; after the reaction is completed, the product is cooled to room temperature under nitrogen protection to obtain the alumina particles with an amorphous silicon oxide layer on the surface.

7. A thermal barrier coating with vertical cracks resistant to CMAS corrosion according to claim 5, characterized in that, The preparation method of the niobium-samarium co-doped yttrium oxide stabilized zirconium oxide matrix powder in the composite spraying powder includes the following steps: (I) Preparation of coprecipitation raw material solution: Zirconium oxychloride, yttrium nitrate, niobium ammonium oxalate and samarium nitrate are used as raw materials, dissolved in deionized water to prepare a coprecipitation raw material solution with a total cation concentration of 0.5-1.0 mol / L; (II) Coprecipitation reaction: At 25-35°C, the coprecipitation raw material solution from step (I) is uniformly added to an ammonia solution with a concentration of 4-6 mol / L within 30-45 minutes, maintaining the final pH value of the reaction system at 9.5-10.5 to generate a coprecipitate; (III) Post-treatment and secondary drying: The coprecipitate is filtered, washed alternately with water and anhydrous ethanol, and dried at 90-110°C for 18-24 hours to obtain mixed hydroxide precursor powder. (IV) Calcination and powder processing: The mixed hydroxide precursor powder is heated to 850-950°C in air at a rate of 3-5°C / min and held for 3-4 hours to obtain niobium-sammarium co-doped yttrium-stabilized zirconia solid solution powder; the solid solution powder is dry ball-milled for 4-6 hours and then passed through a 400-mesh sieve to obtain the niobium-sammarium co-doped yttrium-stabilized zirconia matrix powder.

8. A thermal barrier coating with vertical cracks resistant to CMAS corrosion according to claim 5, characterized in that, The metal bonding layer is NiCoCrAlY alloy spray powder.

9. A method for preparing a thermal barrier coating containing vertical cracks resistant to CMAS corrosion according to any one of claims 1-8, characterized in that, The method includes the following steps: Step 1: Deposit a metal bonding layer. After surface sandblasting and cleaning of the substrate, a high-speed oxygen fuel spraying process is used to deposit NiCoCrAlY alloy powder on the substrate to form a metal bonding layer. Step 2: Deposit a strain buffer intermediate layer. Using rare earth oxide-modified yttrium oxide-stabilized zirconia composite powder as raw material, an atmospheric plasma spraying process is used to deposit a strain buffer intermediate layer on the metal bonding layer. The rare earth oxide-modified yttrium oxide-stabilized zirconia composite powder reacts in a plasma flame to generate rare earth aluminate flakes in situ. Step 3: Deposit the functional composite top layer. Using composite spray powder as raw material, an atmospheric plasma spraying process is used to deposit the functional composite top layer on the strain buffer intermediate layer. Step 4: Post-processing to induce vertical cracks. The product obtained in step 3 is subjected to vacuum high-temperature treatment followed by ultrasonic-assisted rapid cooling to obtain a CMAS corrosion-resistant thermal barrier coating with a synergistic reinforcement structure.

10. A method for preparing a thermal barrier coating containing vertical cracks resistant to CMAS corrosion according to claim 9, characterized in that, In the first step, the process parameters for high-speed oxygen fuel spraying are as follows: the fuel is propane, the oxygen flow rate is 750-850 SLPM, the propane flow rate is 180-220 SLPM, the spraying distance is 320-350 mm, and the powder feeding rate is 45-55 g / min. In the second step, the process parameters for atmospheric plasma spraying are as follows: the main gas is argon, with a flow rate of 38-42 SLPM; the auxiliary gas is hydrogen, with a flow rate of 10-14 SLPM; the spraying current is 520-560 A; the spraying distance is 105-115 mm; and the spray gun moving speed is 450-550 mm / s. In the third step, the process parameters for atmospheric plasma spraying are as follows: the main gas is argon, with a flow rate of 42-46 SLPM; hydrogen is not used as the auxiliary gas. The spraying current is 440-470 A; the spraying distance is 135-145 mm; and the powder feeding rate is 22-28 g / min. In the fourth step, the process parameters of the vacuum high-temperature treatment are as follows: heating at a rate of 8-12°C / min to 1020-1080°C under the condition of a pressure lower than 5x10 -3 Pa, holding for 1.5-2.5 hours, and cooling to 500°C; In the fourth step, the process parameters of the ultrasonic-assisted quenching treatment are as follows: the product after the vacuum high-temperature treatment is immersed in dimethyl silicone oil with a temperature of-10 to 0℃, and ultrasonic waves with a frequency of 25-35 kHz and a power density of 0.8-1.2 W / cm 2 are applied, and the quenching time is 60-90 seconds.

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