Gradient structure ytterbium bisilicate high temperature seal coating and application

Abstract

The application belongs to the field of aero-engine gas path sealing, and discloses a gradient-structure double-ytterbium silicate high-temperature seal coating and application. The seal coating comprises a barrier layer, a transition layer and an abradable surface layer which are sequentially sprayed on a to-be-sprayed base body along the thickness direction of the seal coating; the porosity of the barrier layer is 1-9%; the porosity of the transition layer is 9-18%; the porosity of the abradable surface layer is 18-30%; and the spraying feed powder of the barrier layer, the transition layer and the abradable surface layer is Yb2Si2O7-based powder. The coating has the characteristics of gradient distribution of porosity, high-temperature resistance, CMAS corrosion resistance, moderate hardness and high bonding strength.

Description

Technical Field

[0001] This invention belongs to the field of aero-engine gas path sealing, and more specifically, relates to a gradient structure ytterbium silicate-based high-temperature sealing coating and its application. Background Technology

[0002] In aero engines, the airflow sealing performance has a significant impact on engine efficiency and overall performance. Increased clearance between the blade tip and the casing reduces engine efficiency and increases fuel consumption. Therefore, to prevent blade tip collisions with the casing during operation and damage caused by excessively small clearances, a wear-resistant sealing coating must be applied to improve airflow sealing and protect the blade tip. Traditional sealing coatings include metal-based (such as aluminum-based and nickel-based) sealing coatings and ceramic-based yttrium-stabilized zirconia (YSZ) sealing coatings. Metal-based sealing coatings typically have an service temperature of 300-1100℃. YSZ sealing coatings have a further increased service temperature, reaching up to 1200℃.

[0003] With the rapid development of aviation technology, the thrust-to-weight ratio of aero engines is increasing, leading to turbine inlet temperatures exceeding 1300℃ in new-generation engines. Nickel-based superalloys (service temperature <1200℃) are no longer sufficient to meet current requirements. Silicon carbide ceramic matrix composites possess advantages such as low density, high temperature resistance, and high specific strength, thus becoming a key structural material for hot-section components of new-generation aero engines. At this point, traditional sealing coatings are insufficient to meet the stringent service requirements, necessitating the development of materials with temperature resistance greater than 1300℃ and a thermal expansion coefficient lower than that of silicon carbide composites (4.5×10⁻⁶). -6 -5.5×10 -6 K -1 A matching high-temperature sealing coating.

[0004] Meanwhile, as is well known, the working conditions inside the high-pressure turbine of an aero-engine are extremely complex and harsh. Coated components are subjected to thermal shock from high-temperature and high-speed combustion gases and frequently experience drastic temperature changes. Therefore, the coating is required to effectively alleviate thermal stress and prevent peeling. In addition, the coating also faces CMAS corrosion caused by low-melting-point oxides such as CaO, MgO, Al2O3, and SiO2 introduced from the environment. This is also an important factor leading to the peeling and failure of the sealing coating. Therefore, the coating is also required to have excellent resistance to CMAS corrosion.

[0005] Traditional sealing coatings are typically single-layer coatings with a uniform porous structure. While this uniform structure is simple to manufacture, the coating's bonding strength and corrosion resistance are relatively poor. Furthermore, significant thermal stress is generated between the coating and the substrate during service (due to the large difference in porosity between the porous surface layer and the dense adhesive layer), which can easily lead to cracks at the interface and cause the coating to peel off.

[0006] To address the problems of traditional sealing coatings, there is an urgent need for a novel high-temperature sealing coating with a stable and reliable structure. Therefore, this invention proposes a gradient-structured ytterbium silicate-based sealing coating, which solves the problems of high thermal stress, low bonding strength, and poor corrosion resistance, and effectively improves the service stability, reliability, and service life of the sealing coating. Summary of the Invention

[0007] The purpose of this invention is to address the shortcomings of existing technologies by proposing a gradient-structured ytterbium silicate-based high-temperature sealing coating and its applications. The coating of this invention features a gradient porosity distribution, high temperature resistance, CMAS corrosion resistance, moderate hardness, and high bonding strength.

[0008] To achieve the above objectives, the present invention provides a gradient structure ytterbium silicate-based high-temperature sealing coating, wherein the gradient structure ytterbium silicate-based high-temperature sealing coating comprises a barrier layer, a transition layer and a wearable surface layer sequentially sprayed along the thickness direction of the sealing coating onto a substrate on which a silicon bonding layer has been prepared; The porosity of the barrier layer is 1-9%; The porosity of the transition layer is 9-18%; The porosity of the wear-resistant surface layer is 18-30%; The powder used for spraying the barrier layer, transition layer, and wearable surface layer is Yb2Si2O7-based powder.

[0009] According to the present invention, preferably, the substrate for which the silicon bonding layer has been prepared is a substrate for which corundum abrasive is sprayed onto the surface of a hot-end component substrate for an aero-engine at a pressure of 0.1-0.8 MPa, so that the surface roughness of the substrate is 3-6 μm, and then the silicon bonding layer is sprayed onto the surface.

[0010] According to the present invention, preferably, the powder used for spraying the silicon bonding layer is at least one of Si agglomerated powder, molten and crushed silicon powder and Si-HfO2 composite powder, and its particle size ranges from 10 to 160 μm.

[0011] According to the present invention, preferably, the thickness of the silicon adhesive layer is 50-150 μm.

[0012] According to the present invention, preferably, the thickness of the barrier layer is 0.1-0.4 mm.

[0013] According to the present invention, preferably, the thickness of the transition layer is 0.2-0.6 mm.

[0014] According to the present invention, preferably, the thickness of the wear-resistant surface layer is 0.4-1.0 mm.

[0015] According to the present invention, preferably, the total thickness of the silicon bonding layer, barrier layer, transition layer and wear-resistant surface layer is ≤2.5mm.

[0016] According to the present invention, preferably, the particle size range of the Yb2Si2O7-based powder is 10-200 μm.

[0017] According to the present invention, preferably, the coating is further subjected to heat treatment at a temperature of 350-1100°C for a holding time of 1-20 hours.

[0018] According to the present invention, preferably, the different porosities of the barrier layer, the transition layer and the wearable surface layer are achieved by controlling the mass ratio of polyphenylene ester powder in the Yb2Si2O7-based powder used in each; Based on the total mass of Yb2Si2O7-based powder used in the barrier layer, the content of Yb2Si2O7 powder is greater than 97% and less than 100%, and the content of polystyrene powder is greater than 0% and less than 3%. Based on the total mass of Yb2Si2O7-based powder used in the transition layer, the content of Yb2Si2O7 powder is 94-97%, and the content of polystyrene powder is 3-6%. Based on the total mass of Yb2Si2O7-based powder used in the wearable surface layer, the content of Yb2Si2O7 powder is 90-94%, and the content of polystyrene powder is 6-10%.

[0019] According to the present invention, preferably, when the different porosities of the barrier layer, transition layer and wearable surface layer are achieved by controlling the mass ratio of Yb2Si2O7 powder in the spray feed powder used for each, the spraying process of the barrier layer, transition layer and wearable surface layer are all atmospheric plasma spraying, and the same operating parameters are used, including: the flow rate of working gas Ar is 20-60 L / min, the flow rate of auxiliary gas H2 is 5-16 L / min, the flow rate of carrier gas Ar is 1-6 L / min, the spraying current is 300-700 A, and the spraying distance is 70-150 mm.

[0020] According to the present invention, preferably, the different porosities of the barrier layer, the transition layer and the wearable surface layer are achieved by controlling the operating parameters of the spraying process; The spraying process for the barrier layer, transition layer, and abrasive surface layer is atmospheric plasma spraying, but: The operating parameters for atmospheric plasma spraying of the barrier layer include: the flow rate of working gas Ar is 20-60 L / min, the flow rate of auxiliary gas H2 is 14-18 L / min, the flow rate of carrier gas Ar is 5-7 L / min, the spraying current is 550-700 A, and the spraying distance is 65-90 mm. The operating parameters for atmospheric plasma spraying of the transition layer include: the flow rate of working gas Ar is 20-60 L / min, the flow rate of auxiliary gas H2 is 7-14 L / min, the flow rate of carrier gas Ar is 3.5-5 L / min, the spraying current is 450-550 A, and the spraying distance is 90-115 mm. The operating parameters for atmospheric plasma spraying of abrasive surfaces include: the flow rate of working gas Ar is 20-60 L / min, the flow rate of auxiliary gas H2 is 4-7 L / min, the flow rate of carrier gas Ar is 2-3.5 L / min, the spraying current is 300-450 A, and the spraying distance is 115-150 mm.

[0021] According to the present invention, preferably, the Yb2Si2O7-based powder used in the barrier layer, transition layer and wearable surface layer is a Yb2Si2O7-polyphenylene ester (Yb2Si2O7-PHB) composite powder with the same component dosage; wherein the mass ratio of Yb2Si2O7 powder to polyphenylene ester powder in the Yb2Si2O7-polyphenylene ester composite powder is (93-96)%:(4-7)%.

[0022] In this invention, as a preferred embodiment, the method for preparing the gradient-structured ytterbium silicate-based high-temperature sealing coating includes the following: (1) Sandblasting: roughening the surface of the substrate through sandblasting process; (2) Spraying: The silicon bonding layer, barrier layer, transition layer and wearable surface layer are sequentially sprayed onto the sandblasted pretreated substrate using atmospheric plasma spraying technology.

[0023] (3) Heat treatment: The sprayed coating is subjected to heat treatment.

[0024] Another aspect of the present invention provides the application of the gradient-structured ytterbium silicate-based high-temperature sealing coating on hot-end components of aero-engines.

[0025] The beneficial effects of the technical solution of the present invention are as follows: The Yb2Si2O7-based sealing coating of the present invention has the characteristics of gradient porosity distribution, resistance to high temperature ≥1300℃, resistance to CMAS corrosion, moderate hardness, and high bonding strength (>7MPa), and is expected to become a high-temperature sealing coating for hot-end components of aero-engines; specifically: 1. Ytterbium disilicate (Yb2Si2O7) has a coefficient of thermal expansion that matches that of silicon carbide ceramic matrix composites, a key structural material for current hot-section components of aero-engines (turbine blades, turbine casings). -6 K -1 It also has advantages such as high melting point, high temperature resistance (≥1300℃) and good phase stability, making it suitable as a high-temperature sealing coating material for hot-end components (silicon carbide ceramic matrix composites) of aero-engines; 2. The dual ytterbium silicate-based high-temperature sealing coating designed in this invention has the characteristics of a gradient distribution of porosity along the thickness direction and a gradient change of microstructure, namely a wearable surface layer with high porosity, a transition layer with medium and low porosity, and a barrier layer with low porosity.

[0026] 3. The gradient microstructure in this invention endows the Yb2Si2O7-based sealing coating with many excellent properties: (1) The high porosity (18-30%) surface layer gives the coating a suitable hardness (80-95HR15Y); (2) The low porosity barrier layer (1-9%) and transition layer (9-18%) can effectively ensure the coating's high bonding strength and excellent resistance to CMAS corrosion (effectively hindering the penetration and corrosion of CMAS melt in the service environment); (3) The gradient structure helps to alleviate thermal stress during service, ensuring that the coating has excellent thermal shock resistance, effectively coping with the thermal shock service environment, and ensuring the stability and reliability of the coating.

[0027] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0028] The above and other objects, features and advantages of the present invention will become more apparent from the more detailed description of exemplary embodiments of the invention in conjunction with the accompanying drawings.

[0029] Figure 1 The image shown is a scanning electron microscope (SEM) image of the surface of a gradient-structured ytterbium-based high-temperature sealing coating provided in Embodiment 1 of the present invention.

[0030] Figure 2 The image shows a scanning electron microscope (SEM) image of a cross-section of a gradient-structured ytterbium-based high-temperature sealing coating provided in Embodiment 2 of the present invention.

[0031] Figure 3a -b shows scanning electron microscope (SEM) images and Ca element distribution images of the cross-section of a gradient-structured ytterbium-based high-temperature sealing coating provided in Embodiment 2 of the present invention after CMAS etching.

[0032] Figure 4 The porosity of each layer of a gradient-structured ytterbium silicate-based high-temperature sealing coating provided in Embodiment 3 of the present invention is shown.

[0033] Figure 5 The XRD pattern of a gradient-structured ytterbium silicate-based high-temperature sealing coating provided in Embodiment 4 of the present invention is shown.

[0034] Figure 6a-b shows scanning electron microscope (SEM) images and Ca element distribution images of a cross-section of a gradient-structured ytterbium-based high-temperature sealing coating provided in Comparative Example 1 of the present invention after CMAS etching. Detailed Implementation

[0035] Preferred embodiments of the invention will now be described in more detail. While preferred embodiments of the invention are described below, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0036] In the following embodiments and comparative examples: The porosity test method is as follows: Image-J software is used to analyze the scanned images of the coating cross section. At least 3 backscattered scan images of the coating cross section at different locations are randomly selected for each sample, and the average value of the results is taken to obtain the porosity. The test method for bonding strength is as follows: the tensile test is performed using a dual-sample tester, and the equipment used is a universal testing machine. The bonding strength is obtained by taking the average value of ≥3 samples for each test.

[0037] Example 1

[0038] This embodiment provides a gradient structure ytterbium silicate-based high-temperature sealing coating, wherein the gradient structure sealing coating includes a barrier layer, a transition layer and a wearable surface layer sequentially sprayed along the thickness direction of the sealing coating onto a substrate on which a silicon bonding layer has been prepared.

[0039] The powder used for spraying the barrier layer, transition layer, and wearable surface layer is Yb2Si2O7-based powder with a particle size of 10-140μm; Based on the total mass of Yb2Si2O7-based powder used in the barrier layer, the content of Yb2Si2O7 powder is 99.7%, and the content of polystyrene powder is 0.3%. Based on the total mass of Yb2Si2O7-based powder used in the transition layer, the content of Yb2Si2O7 powder is 96.9%, and the content of polystyrene powder is 3.1%. Based on the total mass of Yb2Si2O7-based powder used in the abrasive surface layer, the content of Yb2Si2O7 powder is 92%, and the content of polystyrene powder is 8% (the different porosities of the barrier layer, transition layer, and abrasive surface layer are achieved by controlling the mass ratio of polystyrene powder in the Yb2Si2O7-based powder used in each layer).

[0040] The method for preparing the gradient-structured ytterbium silicate-based high-temperature sealing coating in this embodiment includes: S1: The silicon carbide substrate is sandblasted with corundum abrasive at a pressure of 0.6 MPa to achieve a surface roughness of 4.8 ± 0.3 μm, thus obtaining a pre-treated substrate.

[0041] S2: Using atmospheric plasma spraying technology, a silicon bonding layer is formed by spraying onto the surface of a substrate that has undergone sandblasting pretreatment, thus obtaining a substrate with a prepared silicon bonding layer. The powder used for spraying the silicon bonding layer is molten and crushed silicon powder with a particle size of 10-90μm. The operating parameters for atmospheric plasma spraying include: the flow rate of working gas Ar is 35 L / min, the flow rate of auxiliary gas H2 is 6 L / min, the flow rate of carrier gas Ar is 3 L / min, the spraying current is 400 A, and the spraying distance is 70 mm.

[0042] S3: Using atmospheric plasma spraying technology, a barrier layer, a transition layer and a wear-resistant surface layer are sequentially sprayed onto the surface of the silicon bonding layer. The spraying process for the barrier layer, transition layer, and wearable surface layer uses the same operating parameters, including: the flow rate of working gas Ar is 30L / min, the flow rate of auxiliary gas H2 is 7L / min, the flow rate of carrier gas Ar is 2L / min, the spraying current is 300A, and the spraying distance is 70mm.

[0043] S4: Heat-treat the coating after spraying in step S3 (hold at 360℃ for 20h) to obtain the gradient structure of the ytterbium silicate-based high-temperature sealing coating (i.e., a silicon bonding layer (thickness 52μm), a barrier layer (thickness 107μm), a transition layer (thickness 213μm) and a wearable surface layer (thickness 405μm) are sequentially stacked on the surface of the substrate that has undergone sandblasting pretreatment).

[0044] The surface microstructure of the high-temperature sealing coating prepared in this embodiment is as follows: Figure 1 As shown, from Figure 1 It can be seen that the coating surface has a porous morphology, consisting of well-melted areas and a few incompletely melted particles, which is consistent with the typical characteristics of the surface morphology of a sealing coating.

[0045] The porosity of the barrier layer of the high-temperature sealing coating prepared in this embodiment is 2.1%; the porosity of the transition layer is 9.1%; and the porosity of the wearable surface layer is 26.0%. The Rockwell hardness is 86.0±1.5HR15Y, and the bonding strength is 7.6±0.6MPa.

[0046] Example 2

[0047] This embodiment provides a gradient structure ytterbium silicate-based high-temperature sealing coating, wherein the gradient structure sealing coating includes a barrier layer, a transition layer and a wearable surface layer sequentially sprayed along the thickness direction of the sealing coating onto a substrate on which a silicon bonding layer has been prepared.

[0048] The powder used for spraying the barrier layer, transition layer, and wearable surface layer is Yb2Si2O7-based powder with a particle size of 20-160μm; Based on the total mass of Yb2Si2O7-based powder used in the barrier layer, the content of Yb2Si2O7 powder is 98.5%, and the content of polystyrene powder is 1.5%. Based on the total mass of Yb2Si2O7-based powder used in the transition layer, the content of Yb2Si2O7 powder is 96%, and the content of polystyrene powder is 4%. Based on the total mass of Yb2Si2O7-based powder used in the abrasive surface layer, the content of Yb2Si2O7 powder is 93.5%, and the content of polystyrene powder is 6.5% (the different porosities of the barrier layer, transition layer, and abrasive surface layer are achieved by controlling the mass ratio of polystyrene powder in the Yb2Si2O7-based powder used in each layer).

[0049] The method for preparing the gradient-structured ytterbium silicate-based high-temperature sealing coating in this embodiment includes: S1: The silicon carbide substrate is sandblasted with corundum abrasive at a pressure of 0.45 MPa to achieve a surface roughness of 3.9 ± 0.4 μm, thus obtaining a pre-treated substrate.

[0050] S2: Using atmospheric plasma spraying technology, a silicon bonding layer is formed by spraying onto the surface of the pre-treated sandblasted substrate to obtain a substrate with a prepared silicon bonding layer. The powder used for spraying the silicon bonding layer is Si agglomerated powder with a particle size of 20-120μm. The operating parameters for atmospheric plasma spraying include: the flow rate of working gas Ar is 45 L / min, the flow rate of auxiliary gas H2 is 9 L / min, the flow rate of carrier gas Ar is 4 L / min, the spraying current is 400 A, and the spraying distance is 90 mm.

[0051] S3: Using atmospheric plasma spraying technology, a barrier layer, a transition layer and a wear-resistant surface layer are sequentially sprayed onto the surface of the silicon bonding layer. The spraying process for the barrier layer, transition layer, and wearable surface layer uses the same operating parameters, including: the flow rate of working gas Ar is 40 L / min, the flow rate of auxiliary gas H2 is 12 L / min, the flow rate of carrier gas Ar is 4 L / min, the spraying current is 400 A, and the spraying distance is 90 mm.

[0052] S4: Heat-treat the coating after spraying in step S3 (hold at 700℃ for 15h) to obtain the gradient structure of the ytterbium silicate-based high-temperature sealing coating (i.e., a silicon bonding layer (thickness 75μm), a barrier layer (thickness 192μm), a transition layer (thickness 285μm) and a wearable surface layer (thickness 504μm) are sequentially stacked on the surface of the substrate that has undergone sandblasting pretreatment).

[0053] The cross-sectional microstructure of the high-temperature sealing coating prepared in this embodiment is as follows: Figure 2 As shown, Figure 2 As can be seen, the porosity of the coating gradually changes along the thickness direction. In this embodiment, the porosity of the barrier layer of the high-temperature sealing coating is 4.1%; the porosity of the transition layer is 12.4%; and the porosity of the wearable surface layer is 19.7%.

[0054] After CMAS etching (CMAS coating amount 30 mg / cm²) 2 The cross-sectional morphology and corresponding Ca element distribution of the sample (corroded at 1300℃ for 10 hours) are shown in the following photographs. Figure 3a As shown in -b, it can be found that Ca is mainly distributed in the wearable surface layer, with a maximum corrosion depth of 712 μm (based on the front edge of Ca distribution) and an average corrosion depth of 681 μm. This indicates that the transition layer and barrier layer can effectively block the penetration and corrosion of CMAS melt.

[0055] The high-temperature sealing coating prepared in this embodiment has a Rockwell hardness of 91.0±1.3HR15Y and a bonding strength of 8.0±0.6MPa.

[0056] Therefore, it can be seen that the wearable sealing coating obtained by the method of the present invention has suitable hardness, good bonding strength and excellent ability to block CMAS melt penetration and corrosion.

[0057] Example 3

[0058] This embodiment provides a gradient structure ytterbium silicate-based high-temperature sealing coating, wherein the gradient structure sealing coating includes a barrier layer, a transition layer and a wearable surface layer sequentially sprayed along the thickness direction of the sealing coating onto a substrate on which a silicon bonding layer has been prepared.

[0059] The powder used for spraying the barrier layer, transition layer, and wearable surface layer is Yb2Si2O7-based powder with a particle size of 30-180μm; Based on the total mass of Yb2Si2O7-based powder used in the barrier layer, the content of Yb2Si2O7 powder is 97.5%, and the content of polystyrene powder is 2.5%. Based on the total mass of Yb2Si2O7-based powder used in the transition layer, the content of Yb2Si2O7 powder is 94%, and the content of polystyrene powder is 6%. Based on the total mass of Yb2Si2O7-based powder used in the abrasive surface layer, the content of Yb2Si2O7 powder is 90%, and the content of polystyrene powder is 10% (the different porosities of the barrier layer, transition layer, and abrasive surface layer are achieved by controlling the mass ratio of polystyrene powder in the Yb2Si2O7-based powder used in each layer).

[0060] The method for preparing the gradient-structured ytterbium silicate-based high-temperature sealing coating in this embodiment includes: S1: The silicon carbide substrate is sandblasted with corundum abrasive at a pressure of 0.3 MPa to achieve a surface roughness of 3.0 ± 0.2 μm, thus obtaining a pre-treated substrate.

[0061] S2: Using atmospheric plasma spraying technology, a silicon bonding layer is formed by spraying onto the surface of the pre-treated sandblasted substrate to obtain a substrate with a prepared silicon bonding layer. The powder used for spraying the silicon bonding layer is a Si-HfO2 composite powder (Si:HfO2=80%:20%) with a particle size of 30-130μm; The operating parameters for atmospheric plasma spraying include: the flow rate of working gas Ar is 60 L / min, the flow rate of auxiliary gas H2 is 10 L / min, the flow rate of carrier gas Ar is 5 L / min, the spraying current is 600 A, and the spraying distance is 100 mm.

[0062] S3: Using atmospheric plasma spraying technology, a barrier layer, a transition layer and a wear-resistant surface layer are sequentially sprayed onto the surface of the silicon bonding layer. The spraying process for the barrier layer, transition layer, and wearable surface layer uses the same operating parameters, including: the flow rate of working gas Ar is 50 L / min, the flow rate of auxiliary gas H2 is 14 L / min, the flow rate of carrier gas Ar is 5 L / min, the spraying current is 500 A, and the spraying distance is 130 mm.

[0063] S4: Heat-treat the coating after spraying in step S3 (hold at 900℃ for 10h) to obtain the gradient structure of the ytterbium silicate-based high-temperature sealing coating (i.e., a silicon bonding layer (thickness 102μm), a barrier layer (thickness 307μm), a transition layer (thickness 408μm) and a wearable surface layer (thickness 704μm) are sequentially stacked on the surface of the substrate that has undergone sandblasting pretreatment).

[0064] The porosity of each layer of the high-temperature sealing coating prepared in this embodiment is as follows: Figure 4As shown, the porosity of the barrier layer is 6.2%; the porosity of the transition layer is 14.5%; and the porosity of the wearable surface layer is 27.6%. The Rockwell hardness is 84.0±1.2HR15Y, and the bonding strength is 7.4±0.1MPa. Therefore, the wearable sealing coating obtained by this method has suitable hardness and good bonding strength.

[0065] Example 4

[0066] This embodiment provides a gradient structure ytterbium silicate-based high-temperature sealing coating, wherein the gradient structure sealing coating includes a barrier layer, a transition layer and a wearable surface layer sequentially sprayed along the thickness direction of the sealing coating onto a substrate on which a silicon bonding layer has been prepared.

[0067] The Yb2Si2O7-based powder used in the barrier layer, transition layer, and wearable surface layer is a Yb2Si2O7-polyphenylene ester composite powder with the same amount of each component and a particle size of 10-200μm; in the Yb2Si2O7-polyphenylene ester composite powder, the mass ratio of Yb2Si2O7 powder to polyphenylene ester powder is 93.5%:6.5% (the different porosities of the barrier layer, transition layer, and wearable surface layer are achieved by controlling the operating parameters of the spraying process).

[0068] The method for preparing the gradient-structured ytterbium silicate-based high-temperature sealing coating in this embodiment includes: S1: The silicon carbide substrate is sandblasted with corundum abrasive at a pressure of 0.45 MPa to achieve a surface roughness of 4.0 ± 0.4 μm, thus obtaining a pre-treated substrate.

[0069] S2: Using atmospheric plasma spraying technology, a silicon bonding layer is formed by spraying onto the surface of the pre-treated sandblasted substrate to obtain a substrate with a prepared silicon bonding layer. The powder used for spraying the silicon bonding layer is a Si agglomerated powder with a particle size of 20-150 μm. The operating parameters for atmospheric plasma spraying include: the flow rate of working gas Ar is 42 L / min, the flow rate of auxiliary gas H2 is 12 L / min, the flow rate of carrier gas Ar is 4 L / min, the spraying current is 400 A, and the spraying distance is 90 mm.

[0070] S3: Using atmospheric plasma spraying technology, a barrier layer, a transition layer and a wear-resistant surface layer are sequentially sprayed onto the surface of the silicon bonding layer. The operating parameters for atmospheric plasma spraying of the barrier layer include: the flow rate of working gas Ar is 40L / min, the flow rate of auxiliary gas H2 is 16L / min, the flow rate of carrier gas Ar is 6L / min, the spraying current is 650A, and the spraying distance is 70mm. The operating parameters for atmospheric plasma spraying of the transition layer include: the flow rate of working gas Ar is 40L / min, the flow rate of auxiliary gas H2 is 10L / min, the flow rate of carrier gas Ar is 4L / min, the spraying current is 500A, and the spraying distance is 100mm. The operating parameters for atmospheric plasma spraying of the wearable surface layer include: the flow rate of working gas Ar is 40L / min, the flow rate of auxiliary gas H2 is 6L / min, the flow rate of carrier gas Ar is 3L / min, the spraying current is 300A, and the spraying distance is 130mm.

[0071] S4: Heat-treat the coating after spraying in step S3 (hold at 1100℃ for 5 hours) to obtain the gradient structure of the ytterbium silicate-based high-temperature sealing coating (i.e., a silicon bonding layer (thickness 120μm), a barrier layer (thickness 412μm), a transition layer (thickness 550μm) and a wearable surface layer (thickness 815μm) are sequentially stacked on the surface of the substrate that has undergone sandblasting pretreatment).

[0072] The XRD pattern of the high-temperature sealing coating prepared in this embodiment is as follows: Figure 5 As shown, the coating is mainly composed of Yb2Si2O7, and also contains a small amount of ytterbium monosilicate (Yb2SiO5). This is due to the decomposition of Yb2Si2O7 in an atmospheric plasma flame at extremely high temperatures.

[0073] The porosity of the barrier layer of the high-temperature sealing coating prepared in this embodiment is 8.4%; the porosity of the transition layer is 16.2%; and the porosity of the wearable surface layer is 22.7%. The Rockwell hardness is 89.1±0.5HR15Y, and the bonding strength is 7.0±0.3MPa.

[0074] Comparative Example 1

[0075] This comparative example provides a ytterbium-based high-temperature sealing coating, wherein the sealing coating is a single-layer sealing coating formed by spraying onto a substrate and then heat-treating it.

[0076] Based on the total mass of the spray feed powder used in the single-layer sealing coating, the content of Yb2Si2O7 powder is 93.5%, the content of polystyrene powder is 6.5%, and the particle size of the spray feed powder is 20-160μm.

[0077] The preparation method of the ytterbium-based high-temperature sealing coating in this comparative example includes: S1: The silicon carbide substrate is sandblasted with corundum abrasive at a pressure of 0.45 MPa to achieve a surface roughness of 3.7 ± 0.2 μm, thus obtaining a pre-treated substrate.

[0078] S2: Using atmospheric plasma spraying technology, a silicon bonding layer is formed by spraying onto the surface of a substrate that has undergone sandblasting pretreatment, thus obtaining a substrate with a prepared silicon bonding layer. The powder used for spraying the silicon bonding layer is Si agglomerated powder with a particle size of 20-120μm. The operating parameters for atmospheric plasma spraying include: the flow rate of working gas Ar is 45 L / min, the flow rate of auxiliary gas H2 is 9 L / min, the flow rate of carrier gas Ar is 4 L / min, the spraying current is 400 A, and the spraying distance is 90 mm.

[0079] S3: Using atmospheric plasma spraying technology, a single-layer sealing coating with uniform porosity is sprayed onto the surface of the silicon bonding layer; The operating parameters for atmospheric plasma spraying include: the flow rate of working gas Ar is 40 L / min, the flow rate of auxiliary gas H2 is 12 L / min, the flow rate of carrier gas Ar is 4 L / min, the spraying current is 400 A, and the spraying distance is 90 mm.

[0080] S4: Heat-treat the coating after spraying in step S3 (hold at 1100℃ for 5 hours) to obtain the ytterbium silicate-based high-temperature sealing coating (i.e., a silicon bonding layer (thickness 116μm) and a single-layer sealing coating (thickness 1185μm) are sequentially stacked on the surface of the roughened substrate).

[0081] The porosity of the monolayer Yb2Si2O7 sealing coating prepared in this comparative example is 21.7%, and the bonding strength is 5.8±0.2MPa.

[0082] The coating prepared in this comparative example was subjected to CMAS etching (CMAS coating amount 30 mg / cm²). 2 The cross-sectional morphology and corresponding Ca element distribution photographs of the samples obtained after corrosion at 1300℃ for 10 hours (under the same conditions as Example 2) are shown below. Figure 6a As shown in -b, it can be seen that the Ca element is distributed relatively deep, with a maximum corrosion depth of 1043 μm and an average corrosion depth of 1021 μm, which is close to the entire coating thickness.

[0083] The comparison with the bonding strength (8.0±0.6MPa) and maximum corrosion depth (712μm) in Example 2 shows that the gradient structure ytterbium silicate-based high-temperature sealing coating (mainly the transition layer and the barrier layer) prepared by the present invention can effectively block the penetration and corrosion of CMAS melt and has higher bonding strength.

[0084] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A gradient-structured ytterbium silicate-based high-temperature sealing coating, characterized in that, The gradient structure of the ytterbium silicate-based high-temperature sealing coating includes a barrier layer, a transition layer, and a wearable surface layer that are sequentially sprayed onto a substrate with a pre-prepared silicon bonding layer along the thickness direction of the sealing coating. The porosity of the barrier layer is 1-9%; The porosity of the transition layer is 9-18%; The porosity of the wear-resistant surface layer is 18-30%; The powder used for spraying the barrier layer, transition layer, and wearable surface layer is Yb2Si2O7-based powder.

2. The gradient-structured ytterbium silicate-based high-temperature sealing coating according to claim 1, wherein, The substrate for the prepared silicon bonding layer is prepared by spraying corundum abrasive at a pressure of 0.1-0.8 MPa onto the surface of the hot end component substrate for aero-engines, so that the surface roughness of the substrate is 3-6 μm, and then spraying the silicon bonding layer onto the surface. The powder used for spraying the silicon bonding layer is at least one of Si agglomerated powder, molten and crushed silicon powder, and Si-HfO2 composite powder, with a particle size range of 10-160 μm.

3. The gradient-structured ytterbium silicate-based high-temperature sealing coating according to claim 2, wherein, The thickness of the silicon bonding layer is 50-150 μm; The thickness of the barrier layer is 0.1-0.4 mm; The thickness of the transition layer is 0.2-0.6 mm; The thickness of the wear-resistant surface layer is 0.4-1.0 mm; The total thickness of the silicon bonding layer, barrier layer, transition layer and wear-resistant surface layer is ≤2.5mm.

4. The gradient-structured ytterbium silicate-based high-temperature sealing coating according to claim 1, wherein, The particle size range of the Yb2Si2O7-based powder is 10-200 μm.

5. The gradient-structured ytterbium silicate-based high-temperature sealing coating according to claim 1, wherein, After spraying, the coating undergoes heat treatment at a temperature of 350-1100℃ for 1-20 hours.

6. The gradient-structured ytterbium silicate-based high-temperature sealing coating according to claim 1, wherein, The different porosities of the barrier layer, transition layer and wearable surface layer are achieved by controlling the mass ratio of polyphenylene powder in the Yb2Si2O7-based powder used in each layer. Based on the total mass of Yb2Si2O7-based powder used in the barrier layer, the content of Yb2Si2O7 powder is greater than 97% and less than 100%, and the content of polystyrene powder is greater than 0% and less than 3%. Based on the total mass of Yb2Si2O7-based powder used in the transition layer, the content of Yb2Si2O7 powder is 94-97%, and the content of polystyrene powder is 3-6%. Based on the total mass of Yb2Si2O7-based powder used in the wearable surface layer, the content of Yb2Si2O7 powder is 90-94%, and the content of polystyrene powder is 6-10%.

7. The gradient-structured ytterbium silicate-based high-temperature sealing coating according to claim 6, wherein, The spraying process for the barrier layer, transition layer, and wearable surface layer is atmospheric plasma spraying, and the same operating parameters are used, including: the flow rate of working gas Ar is 20-60 L / min, the flow rate of auxiliary gas H2 is 5-16 L / min, the flow rate of carrier gas Ar is 1-6 L / min, the spraying current is 300-700 A, and the spraying distance is 70-150 mm.

8. The gradient-structured ytterbium silicate-based high-temperature sealing coating according to claim 1, wherein, Different porosities of the barrier layer, transition layer, and abrasive surface layer can also be achieved by controlling the operating parameters of the spraying process; The spraying process for the barrier layer, transition layer, and abrasive surface layer is atmospheric plasma spraying, but: The operating parameters for atmospheric plasma spraying of the barrier layer include: the flow rate of working gas Ar is 20-60 L / min, the flow rate of auxiliary gas H2 is 14-18 L / min, the flow rate of carrier gas Ar is 5-7 L / min, the spraying current is 550-700 A, and the spraying distance is 65-90 mm. The operating parameters for atmospheric plasma spraying of the transition layer include: the flow rate of working gas Ar is 20-60 L / min, the flow rate of auxiliary gas H2 is 7-14 L / min, the flow rate of carrier gas Ar is 3.5-5 L / min, the spraying current is 450-550 A, and the spraying distance is 90-115 mm. The operating parameters for atmospheric plasma spraying of abrasive surfaces include: the flow rate of working gas Ar is 20-60 L / min, the flow rate of auxiliary gas H2 is 4-7 L / min, the flow rate of carrier gas Ar is 2-3.5 L / min, the spraying current is 300-450 A, and the spraying distance is 115-150 mm.

9. The gradient-structured ytterbium silicate-based high-temperature sealing coating according to claim 8, wherein, The Yb2Si2O7-based powder used in the barrier layer, transition layer and wearable surface layer is a Yb2Si2O7-polyphenylene ester composite powder with the same component dosage; in the Yb2Si2O7-polyphenylene ester composite powder, the mass ratio of Yb2Si2O7 powder to polyphenylene ester powder is (93-96)%: (4-7)%.

10. The application of the gradient-structured ytterbium silicate-based high-temperature sealing coating according to any one of claims 1-9 on hot-end components of aero-engines.

Images