Abradable / environmental barrier composite gradient coating with self-healing function and preparation method thereof

Abstract

The invention discloses an abradable / environmental barrier composite gradient coating with a self-healing function and a preparation method of the abradable / environmental barrier composite gradient coating, and belongs to the technical field of abradable coatings. The four-layer structural design of the Si bonding bottom layer, the Yb2Si2O7-S environmental barrier middle layer, the Yb2SiO5-S environmental barrier middle layer and the LaMgAl11O19-polybenzoate-A abradable surface layer is adopted, and corrosion protection compactness and abrasion protection porosity are both considered through gradient matching of thermal expansion coefficients of materials of all the layers. The coating adopts a full-ceramic coating design without a solid lubricant, a porous easy-to-wear structure is formed through a polybenzoate pore-forming phase, the strength of the coating is improved in cooperation with high-temperature oxidation repair of a self-healing phase, and durability and abradability are balanced. And a differentiated self-healing matching strategy is utilized to ensure that the materials have good chemical compatibility. The preparation process is simple and convenient, has the advantages of low cost and easiness in industrial production, and is suitable for large-scale batch production.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of abradable coating, in particular to an abradable / environmental barrier composite gradient coating with self-healing function and a preparation method thereof. BACKGROUND

[0002] Abradable coating is a key technology to improve the working efficiency, thrust-to-weight ratio, reduce fuel consumption, greenhouse gas emissions and flight accident rate of aero-engine. At present, the turbine outer ring and its metal-based abradable coating made of high-temperature alloy cannot meet the service requirements of more than 1300 ℃ of advanced aero-engine. SiC f / SiC ceramic matrix composites (CMCs) are considered as an ideal candidate material for replacing high-temperature alloy for thermal components including turbine outer ring due to their low density, high temperature resistance, high strength, high modulus and oxidation resistance. However, the development of high-temperature ceramic-based abradable coating suitable for SiC f / SiC CMCs surface still faces three major technical bottlenecks.

[0003] Firstly, SiC f / SiC CMCs are prone to water and oxygen corrosion in actual service environment and need environmental barrier coating for protection. It must be pointed out that a single-layer coating cannot provide both environmental barrier function and abradable function, because the former requires the coating to be dense enough, and the latter requires the coating to have a porous and easy-to-abrade structure. Existing research shows that a multi-layer coating structure is the most effective solution. For example, a Chinese invention patent with publication number CN116535243A discloses an abradable seal coating with low friction coefficient and high volume wear rate and a preparation method thereof. The invention uses Y2O3 stabilized ZrO2-based composite coating as the surface coating, uses rare earth silicate interlayer to bond the surface coating and the Si bonding layer on the surface of the ceramic matrix composite together to form an abradable seal coating composite structure, so that the abradable seal coating structure includes a Si bonding layer, a rare earth silicate interlayer and a Y2O3 stabilized ZrO2-based composite surface layer deposited on the surface of the ceramic matrix composite in sequence. The coating has good abradable seal performance, can reduce the hardness and friction coefficient of the coating, and improve the volume wear rate. However, the thermal expansion coefficient of the Y2O3 stabilized ZrO2-based composite surface layer is quite different from that of its lower layer and the substrate, and the relatively high thermal mismatch stress formed will cause the coating to peel off prematurely and deteriorate the application performance of the coating.

[0004] Secondly, existing high-temperature wearable coatings mainly rely on hexagonal boron nitride as a solid lubricant to reduce friction. For example, Chinese invention patent CN103319920A discloses a composite micro-nano zirconia-based high-temperature wearable sealing coating material and its preparation method. The material is composed of a base phase component A, a base phase component B, a binder component, a solid lubricant component, and a pore-forming component, which are compounded together. The content of each component is as follows: base phase component A 60 wt.%~70 wt.%, base phase component B 15 wt.%~20 wt.%, binder component 5 wt.%~15 wt.%, solid lubricant component 1 wt.%~3 wt.%, and pore-forming component 5 wt.%~8 wt.%. The product is obtained after mixing, spray granulation, and sieving. The above coating material contains 1 wt.%~3 wt.% hexagonal boron nitride solid lubricant, which can improve the hardness and thermal stress distribution of the coating. However, hexagonal boron nitride has an initial oxidation temperature of only 850 °C, and it will rapidly oxidize and decompose at operating temperatures above 1300 °C. This not only causes it to lose its lubricating and friction-reducing effects, but its oxidation products may also have a negative impact on the coating. Although exploring new high-temperature solid lubricants is an important research direction, considering the inherent brittleness of ceramic materials, which gives them discrete and non-sticky characteristics during scraping, the use of porous ceramic coating systems without solid lubricants is currently more feasible.

[0005] Finally, high-temperature coating materials mainly composed of rare-earth silicates and rare-earth aluminates contain a large amount of amorphous phase structure in the sprayed state. The recrystallization process at high temperatures will generate shrinkage stress due to volume changes. The superposition of this stress with the thermal mismatch stress in the multilayer system will lead to a significant increase in the internal stress level of the coating. These stresses are released by the generation of cracks in the coating. Vertical cracks provide a rapid channel for the penetration of corrosive media, while horizontal cracks will exacerbate the risk of coating delamination and peeling. Currently, there is a Chinese invention patent with publication number CN116851231A that provides a ytterbium silicate-based self-healing / wearable / environmentally barrier coating, its preparation method and application. The coating includes, from the inside out, an HfO2-Si+X bonding layer, a Yb2Si2O7-M self-healing layer, and (Yb 0.25 RE1 0.25 RE2 0.25 RE3 0.25The coating consists of a Yb₂Si₂O₇ environmental barrier layer and a Yb₂Si₂O₇-polyester wearable surface layer; an HfO₂-Si+X adhesive layer is in contact with the substrate material. The self-healing factor M of the Yb₂Si₂O₇-M self-healing intermediate layer can oxidize at high temperatures to form a flowing healing phase, thereby filling the internal cracks in the Yb₂Si₂O₇-M self-healing intermediate layer. However, this technology has not yet incorporated a self-healing design for the Yb₂Si₂O₇-polyester wearable surface layer, making it impossible to repair cracks caused by stress during service. With prolonged service, these cracks continue to propagate, not only damaging the already fragile porous structure of the wearable surface layer and causing a decline in wearability, but also becoming a shortcut for corrosive media to further penetrate the coating and the substrate, severely weakening the coating's resistance to SiC. f The protective effect of the SiC CMCs matrix is ​​insufficient to meet the stringent requirements for long-term stable service of next-generation aero engines.

[0006] In summary, the development of SiC f This invention relates to a high-temperature ceramic-based wearable coating on the surface of SiC CMCs, providing a wearable / environmental barrier composite gradient coating with self-healing function and its preparation method. This invention overcomes the aforementioned technical obstacles in the prior art and is of great significance for improving the performance of wearable coatings and expanding their applications. Summary of the Invention

[0007] In view of the above-mentioned deficiencies of the prior art, in a first aspect of the present invention, a wear-resistant / environmental barrier composite gradient coating with a thermal expansion gradient structure and self-healing function is provided, comprising sequentially stacked on SiC f / SiC CMCs substrate surface Si bonding underlayer, Yb2Si2O7-S environmental barrier intermediate layer, Yb2SiO5-S environmental barrier intermediate layer, LaMgAl 11 O 19 - Polyphenylene-A wearable surface layer; wherein, in the Yb2Si2O7-S environmental barrier intermediate layer, S is a self-healing phase Ti3SiC2 or Ti2SiC; in the Yb2SiO5-S environmental barrier intermediate layer, S is a self-healing phase Ti3SiC2 or Ti2SiC; LaMgAl 11 O 19 In the -polyphenylene-A wearable surface layer, polyphenylene is the pore-forming phase, and A is the self-healing phase Ti3AlC2 or Ti2AlC.

[0008] Preferably, in the Yb2Si2O7-S environmental barrier intermediate layer, the mass ratio of Yb2Si2O7 to S is 85~95:5~15.

[0009] Preferably, in the Yb2SiO5-S environmental barrier intermediate layer, the mass ratio of Yb2SiO5 to S is 80~90:10~20.

[0010] Preferably, the LaMgAl 11 O 19 - In the abrasive surface layer of polyphenylene-A, LaMgAl 11 O 19 The mass ratio of polystyrene to A is 70~85:3~10:10~30.

[0011] Preferably, the thickness of the Si bonding substrate is 50-150 μm; the thickness of the Yb₂Si₂O₇-S environmental barrier intermediate layer is 30-80 μm; the thickness of the Yb₂SiO₅-S environmental barrier intermediate layer is 30-80 μm; and the thickness of the LaMgAl 11 O 19 The thickness of the abrasive surface layer of polyphenylene-A is 300~800 μm; the total thickness of the abrasive / environmental barrier composite gradient coating is 400~1100 μm.

[0012] In a second aspect of the present invention, a method for preparing a wearable / environmental barrier composite gradient coating is provided, which has the characteristics of simple and controllable process, low cost and easy industrial production, and includes the following steps: (1) For SiC f / SiC CMCs matrix undergoes pretreatment including grinding, roughening, cleaning, and drying; (2) Atmospheric plasma spraying process is adopted for SiC f / SiC CMCs substrate surface sequentially deposited Si bonding underlayer, Yb2Si2O7-S environmental barrier intermediate layer, Yb2SiO5-S environmental barrier intermediate layer, LaMgAl 11 O 19 - Polyphenylene-A abrasive surface layer; to obtain a composite gradient coating; (3) Heat treatment is performed on the composite gradient coating to complete the formation of the porous structure and self-healing effect of the coating, and a wearable / environmental barrier composite gradient coating is obtained.

[0013] Preferably, in step (1), a 240-400 mesh diamond grinding wheel is used to grind SiC. f The edges of the SiC CMCs substrate are mechanically ground to form a 30°~60° chamfer, in order to reduce stress concentration of the coating in the edge area.

[0014] Preferably, in step (1), a dry sandblasting process is used to polish the SiC. f The SiC CMCs substrate surface is roughened by sandblasting to a surface roughness Ra > 5 μm. The sandblasting medium is 100~200 mesh corundum sand, the sandblasting pressure is 0.2~0.4 MPa, and the sandblasting time is 10~30 s to enhance the adhesion of the coating to the substrate surface.

[0015] Based on the research of this invention, because SiC f The SiC CMCs matrix is ​​relatively brittle, and excessively high sandblasting pressure can easily cause pitting damage to its surface. The selected sandblasting pressure range can meet the roughness requirements while avoiding damage to the matrix and ensuring the integrity of the matrix structure.

[0016] Preferably, in step (1), anhydrous ethanol is used to treat the sandblasted SiC. f The SiC CMCs substrate is subjected to ultrasonic cleaning for 2-3 minutes to remove oil and impurities from the substrate surface and avoid defects in the substrate / adhesive substrate bonding.

[0017] Preferably, in step (1), the cleaned SiC f The SiC CMCs matrix was subjected to constant temperature drying treatment at a temperature of 80~120 ℃ for 5~10 h.

[0018] By using the above pretreatment process, a clean and dry rough surface can be obtained, which provides a reliable guarantee for the uniform deposition of subsequent coatings and their solid bonding with the substrate.

[0019] Preferably, in step (2), before coating deposition, a plasma flow is used to deposit SiC f The SiC CMCs substrate is preheated to a surface temperature of 400~600 ℃.

[0020] According to the research of this invention, increasing the surface temperature of the substrate can effectively alleviate the rapid cooling during coating deposition, thereby improving crystallinity and reducing internal stress in the coating.

[0021] Preferably, in step (2), during the Si bonding underlayer deposition process, argon and hydrogen are used as working gases, with an argon flow rate of 30~40 NLPM, a hydrogen flow rate of 10~15 NLPM, a spraying power of 25~35 kW, a spraying distance of 80~100 mm, a powder feeding rate of 3%~6%, and a Si powder particle size of 10~60 μm.

[0022] Preferably, in step (2), during the deposition of the Yb2Si2O7-S environmental barrier intermediate layer, argon and hydrogen are used as working gases, with an argon flow rate of 25~35 NLPM, a hydrogen flow rate of 8~12 NLPM, a spraying power of 30~40 kW, a spraying distance of 100~120 mm, a powder feeding rate of 5%~10%, and a Yb2Si2O7-S composite powder particle size of 30~130 μm.

[0023] Preferably, in step (2), during the deposition of the Yb2SiO5-S environmental barrier intermediate layer, argon and hydrogen are used as working gases, with an argon flow rate of 25~35 NLPM, a hydrogen flow rate of 8~12 NLPM, a spraying power of 30~40 kW, a spraying distance of 100~120 mm, a powder feeding rate of 5%~10%, and a Yb2SiO5-S composite powder particle size of 30~130 μm.

[0024] Preferably, in step (2), LaMgAl 11 O 19 During the deposition of the polyphenylene-A abrasive surface layer, argon and hydrogen are used as working gases. The argon flow rate is 30~40 NLPM, the hydrogen flow rate is 10~15 NLPM, the spraying power is 25~35kW, the spraying distance is 100~150 mm, and the powder feed rate is 10%~20%. (LaMgAl) 11 O 19 The particle size of the polyphenylene-A composite powder is 40~130 μm.

[0025] The composite gradient coating prepared using the above-mentioned spraying process parameters and powder particle size has good interfacial bonding, high density and few cracks in the bonding underlayer and environmental barrier intermediate layer, and uniform pore distribution and suitable hardness in the wearable surface layer.

[0026] Preferably, in step (3), the coating is subjected to segmented heat treatment in an air atmosphere, the steps of which include: 1) The temperature is increased from room temperature to 500-600 ℃ at a rate of 5-10 ℃ / min and held for 1-3 h. The purpose is to remove the polystyrene pore-forming phase in the wearable surface layer, form a porous structure and reduce hardness. 2) Then, the temperature is increased to 1000-1200 ℃ at a rate of 3-5 ℃ / min and kept at that temperature for 5-10 h to induce oxidation of the self-healing phase in the intermediate layer and wearable surface layer of the environmental barrier, thereby exerting the self-healing function.

[0027] By controlling the heat treatment process in stages, the coating performance can be precisely optimized. The intermediate temperature stage is used to efficiently remove the pore-forming phase to construct a porous structure that meets the wear resistance requirements, while the high temperature stage is used to fully activate the oxidation reaction of the self-healing phase to form a stable crack repair mechanism. Ultimately, the composite gradient coating possesses both excellent wear resistance and self-healing ability, significantly improving its stability and service life under high-temperature operating conditions.

[0028] Based on the above technical solutions, the design concept and principle of this invention are as follows: This application employs a Si bonding underlayer, a Yb2Si2O7-S environmental barrier intermediate layer, a Yb2SiO5-S environmental barrier intermediate layer, and a LaMgAl layer. 11 O19 The thermal expansion gradient structure of the polystyrene-A wear-resistant surface layer is designed to simultaneously achieve dual functions of wear protection and corrosion protection. The synergistic mechanism of the above layers lies in the fact that the first layer of Si, after oxidation, forms a dense SiO2 film, which effectively hinders oxygen permeation, thus protecting SiC. f The SiC CMCs matrix provides basic protection; the thermal expansion coefficient of Yb2Si2O7 in the second layer is 5.5 × 10⁻⁶. -6 ℃ -1 ) and SiC f / SiC CMCs matrix (4.5×10 -6 ℃ -1 ) and Si bonding substrate (4.1×10 -6 ℃ -1 The high degree of matching significantly optimizes the thermal stress distribution of the coating; the third layer, Yb₂SiO₅, possesses excellent resistance to water and oxygen corrosion, further enhancing the protective efficacy of the environmental barrier; the fourth layer, LaMgAl 11 O 19 It not only has ultra-high thermal stability of 1600 ℃, but also plays a significant role in heat insulation due to its low thermal conductivity of 1.5~1.9 W / m·K; the layered structure of Ti3SiC2 or Ti2SiC, Ti3AlC2 or Ti2AlC in the second, third and fourth layers endows it with excellent self-lubricating properties, effectively improving the friction and wear performance of the coating.

[0029] Furthermore, the coating system of this invention enhances its overall performance through self-healing design and solid solution strengthening mechanism. Specifically, the second and third layers incorporate Ti3SiC2 or Ti2SiC self-healing phases to compensate for Si loss caused by the high-temperature decomposition of Yb2Si2O7 and Yb2SiO5 during spraying, ensuring the stability of the coating composition; in the fourth layer, LaMgAl... 11 O 19 Al 3+ (Ionic radius 0.0605 nm) with Ti3AlC2 or Ti2AlC Ti 4+ (Ionic radius 0.0535 nm) Similar radii make Ti 4+ Al can be replaced by solid solution 3+ The solid solution formed can activate the crystal lattice, promote sintering, and thus drive the growth of grains in the wearable surface layer, and promote the transformation of interconnected pores into closed pore structures, thereby improving the coating strength.

[0030] Compared with the YSZ material mainly used in existing technologies, this invention uses LaMgAl, which has better thermal matching properties. 11 O 19As the main phase of the wearable surface layer, Yb₂SiO₅ and Yb₂Si₂O₇ are selected to construct an environmental barrier intermediate layer composite system. However, it still faces the risk of early failure due to crack propagation in complex service environments. Therefore, this invention introduces an oxidation repair mechanism of a self-healing phase, combined with a thermal expansion gradient structure design, to give the composite gradient coating the following advantages: (1) The present invention adopts Si bonding bottom layer / Yb2Si2O7-S environmental barrier intermediate layer / Yb2SiO5-S environmental barrier intermediate layer / LaMgAl 11 O 19 The four-layer structure of the polystyrene-A wear-resistant surface layer has an average coefficient of thermal expansion of 4.1 × 10⁻⁶ for each layer. -6 ℃ -1 6.1×10 -6 ℃ -1 7.9×10 -6 ℃ -1 9.1×10 -6 ℃ -1 By matching the thermal expansion coefficient gradient of each layer of material, the contradiction between "corrosion protection density" and "wear protection porosity" in traditional single-layer coatings is effectively solved. (2) The present invention adopts a full ceramic coating design without solid lubricant. A porous and wear-resistant structure is formed by polyphenylene ester pore-forming phase. Combined with high-temperature oxidation repair of self-healing phase, the coating strength is improved, which breaks through the bottleneck of the difficulty in balancing "durability" and "wearability" in existing high-temperature ceramic-based wearable coatings. (3) In view of the material properties of different functional layers, the present invention adopts a differentiated self-healing matching strategy; the main phase of the wearable surface layer is LaMgAl 11 O 19 The self-healing phases Ti3AlC2 and Ti2AlC are matched, and the main phases Yb2SiO5 and Yb2Si2O7 in the intermediate layer of the environmental barrier are selected from Ti3SiC2 and Ti2SiC self-healing phases to ensure good chemical compatibility between materials and avoid harmful chemical reactions at high temperatures. (4) The coating preparation process adopts conventional atmospheric plasma spraying and box furnace heat treatment, which does not require special equipment. Furthermore, the composite powder achieves batch stability through spray granulation, making it suitable for industrial mass production.

[0031] Compared with the prior art, the present invention has the following advantages and beneficial effects: This invention provides a wearable / environmental barrier composite gradient coating with a thermal expansion gradient structure and self-healing function. The materials have good chemical compatibility, balance the dense corrosion protection and the porous wear protection, and achieve a balance between durability and wearability, thus showing excellent application prospects.

[0032] This invention provides a method for preparing a wearable / environmental barrier composite gradient coating. The process is simple and controllable, and has the advantages of low cost and easy industrial production, making it suitable for large-scale mass production. Attached Figure Description

[0033] Figure 1 A schematic diagram of the structure of a wearable / environmental barrier composite gradient coating; Figure 2 Thermal expansion curves of various coating materials in a wearable / environmental barrier composite gradient coating; Figure 3 Photograph of the tensile fracture surface of the non-self-healing wearable / environmental barrier composite gradient coating obtained in Comparative Example 1. Figure 4 Photograph of the tensile fracture surface of the self-healing wear-resistant / environmental barrier composite gradient coating obtained in Example 3; Figure 5 The image shows the microstructure of the wearable / environmental barrier composite gradient coating; among which, Figure 5 (a) is a microstructure of the non-self-healing wearable / environmental barrier composite gradient coating obtained in Comparative Example 1. Figure 5 (b) is a microscopic morphology diagram of the self-healing wearable / environmental barrier composite gradient coating obtained in Example 3. Detailed Implementation

[0034] The present invention is further illustrated below by way of embodiments, but the invention is not limited to the scope of the embodiments described herein. Experimental methods in the following embodiments that do not specify specific conditions were performed according to conventional methods and conditions, or as selected according to the product instructions.

[0035] In the following embodiments: The Si powder was purchased from Shanghai Shuitian Materials Technology Co., Ltd., with a purity of 99.99%. Yb₂Si₂O₇, Yb₂SiO₅, LaMgAl 11 O 19 All raw materials are self-made solid-phase synthesis products with a purity >98%; The raw materials Ti3SiC2, Ti2SiC, Ti3AlC2, and Ti2AlC were purchased from Beijing Huawirui Chemical Technology Co., Ltd., with a purity of 99%. The polystyrene raw material was purchased from Jiashan Fluoride Engineering Materials Co., Ltd., with a purity of 99%. Yb₂Si₂O₇-S, Yb₂SiO₅-S and LaMgAl 11 O 19 The polyphenylene oxide-A composite powder is prepared from the above raw materials by spray granulation, which is a conventional powder preparation process known to those skilled in the art. The present invention does not impose any special limitations on its specific operating parameters.

[0036] Example 1 This embodiment provides a wear-resistant / environmental barrier composite gradient coating with self-healing function, the structure of which is as follows: Figure 1 As shown.

[0037] The thickness design of each layer in the wearable / environmental barrier composite gradient coating is as follows: the thickness of the Si bonding underlayer is 70 μm; the thickness of the Yb2Si2O7-S environmental barrier intermediate layer is 40 μm; the thickness of the Yb2SiO5-S environmental barrier intermediate layer is 40 μm; the thickness of the LaMgAl layer is... 11 O 19 The thickness of the polystyrene-A abrasive surface layer is 380 μm, and the total thickness of the abrasive / environmental barrier composite gradient coating is 530 μm. Meanwhile, the mass ratios of the components in each layer are as follows: Yb₂Si₂O₇-S environmental barrier intermediate layer: Yb₂Si₂O₇ to S mass ratio is 85:15; Yb₂SiO₅-S environmental barrier intermediate layer: Yb₂SiO₅ to S mass ratio is 90:10; LaMgAl 11 O 19 -Polyphenylene-A abrasive surface layer LaMgAl 11 O 19 The mass ratio of polystyrene to A is 85:3:12. Furthermore, the self-healing phase S is Ti3SiC2, and the self-healing phase A is Ti3AlC2.

[0038] The preparation method of the wear-resistant / environmental barrier composite gradient coating with self-healing function in this embodiment is as follows: (1) First, a 240-mesh diamond grinding wheel was used to grind SiC. f The edges of the SiC CMCs matrix are mechanically ground to form a 30° chamfer; subsequently, the ground SiC is sandblasted using a dry sandblasting machine. f The surface of the SiC CMCs substrate was roughened by sandblasting to a surface roughness Ra≈7 μm. The sandblasting medium was 150-mesh corundum abrasive, the sandblasting pressure was 0.3 MPa, and the sandblasting time was 10 s. Then, anhydrous ethanol was used to roughen the surface of the sandblasted SiC. f The SiC CMCs matrix was ultrasonically cleaned for 3 minutes; finally, the cleaned SiC... f The SiC CMCs matrix was placed in an oven for constant temperature drying at 100 ℃ for 5 h.

[0039] (2) The SiC obtained in step (1) f The SiC CMCs matrix is ​​fixed on the worktable, and the SiC is preheated by plasma flame. f The SiC CMCs substrate reaches a surface temperature of 400 ℃; subsequently, atmospheric plasma spraying technology is used to coat the SiC...f A Si bonding underlayer was deposited on the surface of a SiCCMCs substrate using an argon flow rate of 30 NLPM, a hydrogen flow rate of 10 NLPM, a spraying power of 30 kW, a spraying distance of 90 mm, and a powder feed rate of 5%. The Si powder particle size was 20–60 μm. Subsequently, a Yb₂Si₂O₇-S environmental barrier interlayer was deposited on the surface of the Si bonding underlayer using an argon flow rate of 28 NLPM, a hydrogen flow rate of 9 NLPM, a spraying power of 40 kW, a spraying distance of 100 mm, and a powder feed rate of 5%. The Yb₂Si₂O₇-S composite powder particle size was 30–120 μm. Further, a Yb₂SiO₅-S environmental barrier interlayer was deposited on the surface of the Yb₂Si₂O₇-S environmental barrier interlayer using an argon flow rate of 28 NLPM, a hydrogen flow rate of 9 NLPM, a spraying power of 40 kW, a spraying distance of 100 mm, and a powder feed rate of 5%. The Yb₂SiO₅-S composite powder particle size was 30–120 μm. μm; Finally, LaMgAl was deposited on the surface of the Yb2SiO5-S environmental barrier intermediate layer. 11 O 19 - Polystyrene-A abrasive surface coating, argon flow rate 36 NLPM, hydrogen flow rate 12 NLPM, spraying power 32 kW, spraying distance 120 mm, powder feed rate 10%, LaMgAl 11 O 19 The particle size of the polyphenylene-A composite powder is 50~110 μm.

[0040] (3) The coating sample obtained in step (2) is placed in a high-temperature box furnace and subjected to segmented heat treatment in an air atmosphere. The process is to raise the temperature from room temperature to 550℃ at 5℃ / min and hold it for 1 h, and then raise it to 1000℃ at 5℃ / min and hold it for 5 h, thus preparing a wearable / environmental barrier composite gradient coating that achieves self-healing effect.

[0041] Example 2 This embodiment provides a wear-resistant / environmental barrier composite gradient coating with self-healing function, the structure of which is as follows: Figure 1 As shown.

[0042] The thickness design of each layer in the wearable / environmental barrier composite gradient coating is as follows: the thickness of the Si bonding underlayer is 120 μm; the thickness of the Yb2Si2O7-S environmental barrier intermediate layer is 60 μm; the thickness of the Yb2SiO5-S environmental barrier intermediate layer is 60 μm; the thickness of the LaMgAl layer is... 11 O 19The thickness of the polystyrene-A abrasive topcoat is 600 μm, and the total thickness of the abrasive / environmental barrier composite gradient coating is 840 μm. Meanwhile, the mass ratios of the components in each layer are as follows: in the Yb2Si2O7-S environmental barrier intermediate layer, the mass ratio of Yb2Si2O7 to S is 90:10; in the Yb2SiO5-S environmental barrier intermediate layer, the mass ratio of Yb2SiO5 to S is 80:20; LaMgAl... 11 O 19 -Polyphenylene-A abrasive surface layer LaMgAl 11 O 19 The mass ratio of polystyrene to A is 80:7:13. Furthermore, the self-healing phase S is Ti₂SiC, and the self-healing phase A is Ti₂AlC.

[0043] The preparation method of the wear-resistant / environmental barrier composite gradient coating with self-healing function in this embodiment is as follows: (1) First, SiC was polished using a 320-mesh diamond grinding wheel. f The edges of the SiC CMCs matrix are mechanically ground to form a 60° chamfer; subsequently, the ground SiC is sandblasted using a dry sandblasting machine. f The surface of the SiC CMCs substrate was roughened by sandblasting to a surface roughness Ra≈6 μm. The sandblasting medium was 100-mesh corundum abrasive, the sandblasting pressure was 0.2 MPa, and the sandblasting time was 30 s. Then, anhydrous ethanol was used to roughen the surface of the sandblasted SiC. f The SiC CMCs matrix was ultrasonically cleaned for 2 minutes; finally, the cleaned SiC... f The SiC CMCs matrix was placed in an oven for constant temperature drying at 80 ℃ for 8 h.

[0044] (2) The SiC obtained in step (1) f The SiC CMCs matrix is ​​fixed on the worktable, and the SiC is preheated by plasma flame. f The SiC CMCs substrate reaches a surface temperature of 600 ℃; subsequently, atmospheric plasma spraying technology is used to coat the SiC... fA Si bonding underlayer was deposited on the surface of a SiCCMCs substrate using an argon flow rate of 38 NLPM, a hydrogen flow rate of 13 NLPM, a spraying power of 27 kW, a spraying distance of 80 mm, and a powder feed rate of 3%. The Si powder particle size was 10–40 μm. Subsequently, a Yb₂Si₂O₇-S environmental barrier interlayer was deposited on the surface of the Si bonding underlayer using an argon flow rate of 33 NLPM, a hydrogen flow rate of 11 NLPM, a spraying power of 30 kW, a spraying distance of 120 mm, and a powder feed rate of 8%. The Yb₂Si₂O₇-S composite powder particle size was 40–130 μm. Further, a Yb₂SiO₅-S environmental barrier interlayer was deposited on the surface of the Yb₂Si₂O₇-S environmental barrier interlayer using an argon flow rate of 32 NLPM, a hydrogen flow rate of 11 NLPM, a spraying power of 30 kW, and a spraying distance of 120 mm. The powder feeding rate was 8%, and the particle size of the Yb₂SiO₅-S composite powder was 40~130 μm; finally, LaMgAl was deposited on the surface of the Yb₂SiO₅-S environmental barrier intermediate layer. 11 O 19 - Polystyrene-A abrasive surface coating, argon flow rate 34 NLPM, hydrogen flow rate 12 NLPM, spraying power 25 kW, spraying distance 100 mm, powder feed rate 12%, LaMgAl 11 O 19 The particle size of the polyphenylene-A composite powder is 60~120 μm.

[0045] (3) The coating sample obtained in step (2) is placed in a high-temperature box furnace and subjected to segmented heat treatment in an air atmosphere. The process is to raise the temperature from room temperature to 500 ℃ at 7 ℃ / min and hold it for 2 h, and then raise it to 1100 ℃ at 4 ℃ / min and hold it for 8 h, thus preparing a wearable / environmental barrier composite gradient coating that achieves self-healing effect.

[0046] Example 3 This embodiment provides a wear-resistant / environmental barrier composite gradient coating with self-healing function, the structure of which is as follows: Figure 1 As shown.

[0047] The thickness design of each layer in the wearable / environmental barrier composite gradient coating is as follows: the thickness of the Si bonding underlayer is 110 μm; the thickness of the Yb2Si2O7-S environmental barrier intermediate layer is 50 μm; the thickness of the Yb2SiO5-S environmental barrier intermediate layer is 50 μm; the thickness of the LaMgAl layer is... 11 O 19The thickness of the polystyrene-A abrasive surface layer is 550 μm, and the total thickness of the abrasive / environmental barrier composite gradient coating is 760 μm. Meanwhile, the mass ratios of the components in each layer are as follows: in the Yb2Si2O7-S environmental barrier intermediate layer, the mass ratio of Yb2Si2O7 to S is 93:7; in the Yb2SiO5-S environmental barrier intermediate layer, the mass ratio of Yb2SiO5 to S is 85:15; LaMgAl... 11 O 19 -Polyphenylene-A abrasive surface layer LaMgAl 11 O 19 The mass ratio of polystyrene to A is 75:5:20. Furthermore, the self-healing phase S is Ti3SiC2, and the self-healing phase A is Ti3AlC2.

[0048] The preparation method of the wear-resistant / environmental barrier composite gradient coating with self-healing function in this embodiment is as follows: (1) First, a 400-mesh diamond grinding wheel was used to grind SiC. f The edges of the SiC CMCs matrix are mechanically ground to form a 45° chamfer; subsequently, the ground SiC is sandblasted using a dry sandblasting machine. f The surface of the SiC CMCs substrate was roughened by sandblasting to a surface roughness Ra≈6 μm. The sandblasting medium was 120-mesh corundum abrasive, the sandblasting pressure was 0.3 MPa, and the sandblasting time was 15 s. Then, anhydrous ethanol was used to roughen the surface of the sandblasted SiC. f The SiC CMCs matrix was ultrasonically cleaned for 3 minutes; finally, the cleaned SiC... f The SiC CMCs matrix was placed in an oven for constant temperature drying at 100 ℃ for 6 h.

[0049] (2) The SiC obtained in step (1) f The SiC CMCs matrix is ​​fixed on the worktable, and the SiC is preheated by plasma flame. f The SiC CMCs substrate reaches a surface temperature of 500 ℃; subsequently, atmospheric plasma spraying technology is used to coat the SiC... fA Si bonding underlayer was deposited on the surface of a SiCCMCs substrate using an argon flow rate of 36 NLPM, a hydrogen flow rate of 12 NLPM, a spraying power of 32 kW, a spraying distance of 100 mm, and a powder feed rate of 6%. The Si powder particle size was 30–50 μm. Subsequently, a Yb₂Si₂O₇-S environmental barrier interlayer was deposited on the surface of the Si bonding underlayer using an argon flow rate of 30 NLPM, a hydrogen flow rate of 10 NLPM, a spraying power of 35 kW, a spraying distance of 110 mm, and a powder feed rate of 10%. The Yb₂Si₂O₇-S composite powder particle size was 40–110 μm. Further, a Yb₂SiO₅-S environmental barrier interlayer was deposited on the surface of the Yb₂Si₂O₇-S environmental barrier interlayer using an argon flow rate of 30 NLPM, a hydrogen flow rate of 10 NLPM, a spraying power of 35 kW, and a spraying distance of 110 mm. The powder feeding rate was 10%, and the particle size of the Yb₂SiO₅-S composite powder was 40~110 μm; finally, LaMgAl was deposited on the surface of the Yb₂SiO₅-S environmental barrier intermediate layer. 11 O 19 - Polystyrene-A abrasive surface coating, argon flow rate 33 NLPM, hydrogen flow rate 11 NLPM, spraying power 28 kW, spraying distance 130 mm, powder feed rate 15%, LaMgAl 11 O 19 The particle size of the polyphenylene-A composite powder is 60~120 μm.

[0050] (3) The coating sample obtained in step (2) is placed in a high-temperature box furnace and subjected to segmented heat treatment in an air atmosphere. The process is to raise the temperature from room temperature to 600 ℃ at 7 ℃ / min and hold it for 1.5 h, and then raise the temperature to 1200 ℃ at 5 ℃ / min and hold it for 6 h, thus preparing a wearable / environmental barrier composite gradient coating that achieves self-healing effect.

[0051] Example 4 This embodiment provides a wear-resistant / environmental barrier composite gradient coating with self-healing function, the structure of which is as follows: Figure 1 As shown.

[0052] The thickness design of each layer in the wearable / environmental barrier composite gradient coating is as follows: the thickness of the Si bonding underlayer is 80 μm; the thickness of the Yb2Si2O7-S environmental barrier intermediate layer is 70 μm; the thickness of the Yb2SiO5-S environmental barrier intermediate layer is 70 μm; the thickness of the LaMgAl layer is... 11 O 19The thickness of the polystyrene-A abrasive surface layer is 570 μm, and the total thickness of the abrasive / environmental barrier composite gradient coating is 790 μm. Meanwhile, the mass ratios of the components in each layer are as follows: In the Yb2Si2O7-S environmental barrier intermediate layer, the mass ratio of Yb2Si2O7 to S is 95:5; in the Yb2SiO5-S environmental barrier intermediate layer, the mass ratio of Yb2SiO5 to S is 88:12; LaMgAl... 11 O 19 -Polyphenylene-A abrasive surface layer LaMgAl 11 O 19 The mass ratio of polystyrene to A is 70:10:20. Furthermore, the self-healing phase S is Ti₂SiC, and the self-healing phase A is Ti₂AlC.

[0053] The preparation method of the wear-resistant / environmental barrier composite gradient coating with self-healing function in this embodiment is as follows: (1) First, a 280-mesh diamond grinding wheel was used to grind SiC. f The edges of the SiC CMCs matrix are mechanically ground to form a 30° chamfer; subsequently, the ground SiC is sandblasted using a dry sandblasting machine. f The SiC CMCs substrate surface was roughened by sandblasting to a surface roughness Ra≈8 μm. The sandblasting medium was 200-mesh corundum abrasive, the sandblasting pressure was 0.4 MPa, and the sandblasting time was 20 s. Then, anhydrous ethanol was used to treat the sandblasted SiC... f The SiC CMCs matrix was ultrasonically cleaned for 2.5 minutes; finally, the cleaned SiC... f The SiC CMCs matrix was placed in an oven for constant temperature drying at 120 ℃ for 10 h.

[0054] (2) The SiC obtained in step (1) f The SiC CMCs matrix is ​​fixed on the worktable, and the SiC is preheated by plasma flame. f The SiC CMCs substrate reaches a surface temperature of 400 ℃; subsequently, atmospheric plasma spraying technology is used to coat the SiC... fA Si bonding underlayer was deposited on the surface of a SiCCMCs substrate using an argon flow rate of 33 NLPM, a hydrogen flow rate of 11 NLPM, a spraying power of 35 kW, a spraying distance of 100 mm, a powder feed rate of 4%, and Si powder particle size of 20–50 μm. Subsequently, a Yb₂Si₂O₇-S environmental barrier interlayer was deposited on the surface of the Si bonding underlayer using an argon flow rate of 36 NLPM, a hydrogen flow rate of 12 NLPM, a spraying power of 30 kW, a spraying distance of 100 mm, and a powder feed rate of 5%. The Yb₂Si₂O₇-S composite powder particle size of 50–100 μm was then deposited. Further, a Yb₂SiO₅-S environmental barrier interlayer was deposited on the surface of the Yb₂Si₂O₇-S environmental barrier interlayer using an argon flow rate of 35 NLPM, a hydrogen flow rate of 12 NLPM, a spraying power of 30 kW, and a spraying distance of 100 mm. The powder feeding rate was 5%, and the particle size of the Yb₂SiO₅-S composite powder was 50~100 μm; finally, LaMgAl was deposited on the surface of the Yb₂SiO₅-S environmental barrier intermediate layer. 11 O 19 - Polystyrene-A abrasive surface coating, argon flow rate 30 NLPM, hydrogen flow rate 10 NLPM, spraying power 35 kW, spraying distance 140 mm, powder feed rate 12%, LaMgAl 11 O 19 The particle size of the polyphenylene-A composite powder is 50~130 μm.

[0055] (3) The coating sample obtained in step (2) is placed in a high-temperature box furnace and subjected to segmented heat treatment in an air atmosphere. The process is to raise the temperature from room temperature to 600 ℃ at 10 ℃ / min and hold it for 2.5 h, and then raise the temperature to 1100 ℃ at 3 ℃ / min and hold it for 10 h, thus preparing a wearable / environmental barrier composite gradient coating that achieves self-healing effect.

[0056] Example 5 This embodiment provides a wear-resistant / environmental barrier composite gradient coating with self-healing function, the structure of which is as follows: Figure 1 As shown.

[0057] The thickness design of each layer in the wearable / environmental barrier composite gradient coating is as follows: the thickness of the Si bonding underlayer is 130 μm; the thickness of the Yb2Si2O7-S environmental barrier intermediate layer is 80 μm; the thickness of the Yb2SiO5-S environmental barrier intermediate layer is 80 μm; the thickness of the LaMgAl layer is... 11 O 19The thickness of the polystyrene-A abrasive surface layer is 720 μm, and the total thickness of the abrasive / environmental barrier composite gradient coating is 1010 μm. Meanwhile, the mass ratios of the components in each layer are as follows: In the Yb2Si2O7-S environmental barrier intermediate layer, the mass ratio of Yb2Si2O7 to S is 88:12; in the Yb2SiO5-S environmental barrier intermediate layer, the mass ratio of Yb2SiO5 to S is 83:17; LaMgAl... 11 O 19 -Polyphenylene-A abrasive surface layer LaMgAl 11 O 19 The mass ratio of polystyrene to A is 78:6:16. Furthermore, the self-healing phase S is Ti3SiC2, and the self-healing phase A is Ti3AlC2.

[0058] The preparation method of the wear-resistant / environmental barrier composite gradient coating with self-healing function in this embodiment is as follows: (1) First, a 360-mesh diamond grinding wheel was used to grind SiC. f The edges of the SiC CMCs matrix are mechanically ground to form a 60° chamfer; subsequently, the ground SiC is sandblasted using a dry sandblasting machine. f The SiC CMCs substrate surface was roughened by sandblasting to a surface roughness Ra≈7 μm. The sandblasting medium was 150-mesh corundum abrasive, the sandblasting pressure was 0.3 MPa, and the sandblasting time was 25 s. Then, anhydrous ethanol was used to treat the sandblasted SiC... f The SiC CMCs matrix was ultrasonically cleaned for 3 minutes; finally, the cleaned SiC... f The SiC CMCs matrix was placed in an oven for constant temperature drying at 80 ℃ for 6 h.

[0059] (2) The SiC obtained in step (1) f The SiC CMCs matrix is ​​fixed on the worktable, and the SiC is preheated by plasma flame. f The SiC CMCs substrate reaches a surface temperature of 500 ℃; subsequently, atmospheric plasma spraying technology is used to coat the SiC... fA Si bonding underlayer was deposited on the surface of a SiCCMCs substrate using an argon flow rate of 36 NLPM, a hydrogen flow rate of 12 NLPM, a spraying power of 30 kW, a spraying distance of 90 mm, a powder feed rate of 5%, and Si powder particle size of 30–60 μm. Subsequently, a Yb₂Si₂O₇-S environmental barrier interlayer was deposited on the surface of the Si bonding underlayer using an argon flow rate of 30 NLPM, a hydrogen flow rate of 10 NLPM, a spraying power of 40 kW, a spraying distance of 120 mm, and a powder feed rate of 6%. The Yb₂Si₂O₇-S composite powder particle size of 30–110 μm was then deposited. Further, a Yb₂SiO₅-S environmental barrier interlayer was deposited on the surface of the Yb₂Si₂O₇-S environmental barrier interlayer using an argon flow rate of 30 NLPM, a hydrogen flow rate of 10 NLPM, a spraying power of 40 kW, and a spraying distance of 120 mm. The powder feeding rate was 6%, and the particle size of the Yb₂SiO₅-S composite powder was 30~110 μm; finally, LaMgAl was deposited on the surface of the Yb₂SiO₅-S environmental barrier intermediate layer. 11 O 19 - Polystyrene-A abrasive surface coating, argon flow rate 38 NLPM, hydrogen flow rate 13 NLPM, spraying power 30 kW, spraying distance 120 mm, powder feed rate 10%, LaMgAl 11 O 19 The particle size of the polyphenylene-A composite powder is 40~100 μm.

[0060] (3) The coating sample obtained in step (2) is placed in a high-temperature box furnace and subjected to segmented heat treatment in an air atmosphere. The process is to raise the temperature from room temperature to 500 ℃ at 10 ℃ / min and hold it for 3 h, and then raise it to 1200 ℃ at 4 ℃ / min and hold it for 7 h, thus preparing a wearable / environmental barrier composite gradient coating that achieves self-healing effect.

[0061] Comparative Example 1 This comparative example is basically the same as Example 3, except that in step (2) this comparative example uses a Yb2Si2O7 and Yb2SiO5 environmental barrier intermediate layer without a self-healing phase and LaMgAl. 11 O 19 - A polyphenylene abrasive surface layer is obtained after step (3), and the resulting coating is a non-self-healing abrasive / environmental barrier composite gradient coating.

[0062] Test Example 1 This test example illustrates the effect of the self-healing process on the mechanical properties of the wearable / environmental barrier composite gradient coating. The Rockwell hardness (according to ASTM E18-25 standard) and bond strength (according to GB / T 8642-2002 standard) of the heat-treated coating surfaces in Examples 1-5 and Comparative Example 1 were tested, and the test results are shown in Table 1.

[0063] Table 1: Test results of Rockwell hardness and bonding strength of the coating surface

[0064] As shown in Table 1, the coating bonding strength of Examples 1 to 5 is significantly improved by 25.5% to 58.8% compared with Comparative Example 1, while the surface Rockwell hardness only increases slightly by 4.2% to 19.0%. This indicates that the present invention can obtain a wearable / environmental barrier composite gradient coating with good mechanical properties.

[0065] Test Example 2 Using the coating preparation process of Example 1 of this invention, Si, Yb2Si2O7-S, Yb2SiO5-S, and LaMgAl were prepared respectively. 11 O 19 A polystyrene-A monolayer coating was applied, followed by heat treatment until a stable state was achieved. Finally, the thermal expansion behavior of the monolayer coating in air was characterized in the range from room temperature to 1300 °C. The results are as follows: Figure 2 As shown in the figure, the thermal expansion curves of each layer of material exhibit a gradient increasing trend. The multi-layer coating structure constructed in this way possesses excellent stress relief function and can effectively improve the coating's resistance to peeling.

[0066] The tensile fracture surface of the non-self-healing wearable / environmental barrier composite gradient coating prepared in Comparative Example 1 of this invention was observed, and the results are as follows: Figure 3 As shown in the figure, tensile fracture mainly occurs inside the non-self-healing wearable surface layer, and secondarily at the substrate / bond interface. This indicates that the non-self-healing wearable surface layer is the weakest part of the entire coating structure, and also shows that the measured bond strength result (5.1 MPa) can be roughly equivalent to the cohesive strength of the non-self-healing wearable surface layer.

[0067] The tensile fracture surface of the self-healing wear-resistant / environmental barrier composite gradient coating prepared in Example 3 of this invention was observed, and the results are as follows: Figure 4 As shown in the figure, tensile fracture occurs at the substrate / bond interface, indicating that this interface is the weakest point in the entire coating structure. This also demonstrates that the cohesive strength of the self-healing wearable surface layer is greater than the measured bond strength (7.8 MPa). Compared to Comparative Example 1, the cohesive strength of the self-healing wearable surface layer in Example 3 is significantly improved, which allows the weakest point in the coating structure to shift from the interior of the wearable surface layer to the substrate / bond interface.

[0068] Figure 5 This is a microstructure image of the wear-resistant / environmental barrier composite gradient coating in this invention. Figure 5(a) is a microstructure of the non-self-healing wearable / environmental barrier composite gradient coating obtained in Comparative Example 1. Figure 5 (b) is a microstructure diagram of the self-healing abrasive / environmental barrier composite gradient coating obtained in Example 3. As can be seen from the figure, the non-self-healing abrasive / environmental barrier composite gradient coating contains a large number of cracks, and the interconnectivity between pores is obvious. In contrast, the number of cracks in the self-healing abrasive / environmental barrier composite gradient coating is significantly reduced, and the proportion of closed pores is significantly increased. This fully demonstrates that the self-healing process can effectively repair cracks and promote the transformation of interconnected pores into closed-pore structures within the coating, thereby improving the coating strength. Figure 5 Structural evolution of the intermediate coating layer at the microscopic level and Figures 3-4 The corresponding changes in the macroscopic mechanical behavior of the intermediate coating layer jointly confirm the optimizing effect of the self-healing treatment on the coating performance.

[0069] In summary, the wear-resistant / environmental barrier composite gradient coating of the present invention employs a Si bonding underlayer / Yb2Si2O7-S environmental barrier intermediate layer / Yb2SiO5-S environmental barrier intermediate layer / LaMgAl 11 O 19 The four-layer structure design of the polystyrene-A wearable surface layer effectively solves the contradiction between "corrosion protection density" and "wear protection porosity" in traditional single-layer coatings by matching the thermal expansion coefficients of each layer. The wearable / environmental barrier composite gradient coating adopts a solid lubricant-free all-ceramic coating design. A porous, easily wearable structure is formed through the polystyrene pore-forming phase, and the high-temperature oxidation repair of the self-healing phase improves the coating strength, overcoming the bottleneck of balancing "durability" and "wearability" in existing high-temperature ceramic-based wearable coatings. For the material characteristics of different functional layers, this invention adopts a differentiated self-healing matching strategy to ensure good chemical compatibility between materials and avoid harmful chemical reactions at high temperatures. The coating preparation process uses conventional atmospheric plasma spraying and box furnace heat treatment, requiring no special equipment. Furthermore, the composite powder achieves batch stability through spray granulation, making it suitable for industrial mass production.

[0070] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A wearable / environmental barrier composite gradient coating, characterized in that: Abrasion-resistant / environmentally barrier composite gradient coatings consist of sequentially stacked layers on SiC f / SiC CMCs substrate surface Si bonding underlayer, Yb2Si2O7-S environmental barrier intermediate layer, Yb2SiO5-S environmental barrier intermediate layer, LaMgAl 11 O 19 - Polyphenylene-A wearable surface layer; wherein, in the Yb2Si2O7-S environmental barrier intermediate layer, S is a self-healing phase Ti3SiC2 or Ti2SiC; in the Yb2SiO5-S environmental barrier intermediate layer, S is a self-healing phase Ti3SiC2 or Ti2SiC; LaMgAl 11 O 19 In the -polyphenylene-A wearable surface layer, polyphenylene is the pore-forming phase, and A is the self-healing phase Ti3AlC2 or Ti2AlC.

2. The wear-resistant / environmental barrier composite gradient coating according to claim 1, characterized in that: In the Yb2Si2O7-S environmental barrier intermediate layer, the mass ratio of Yb2Si2O7 to S is 85~95:5~15.

3. The wear-resistant / environmental barrier composite gradient coating according to claim 1, characterized in that: In the Yb2SiO5-S environmental barrier intermediate layer, the mass ratio of Yb2SiO5 to S is 80~90:10~20.

4. The wear-resistant / environmental barrier composite gradient coating according to claim 1, characterized in that: The LaMgAl 11 O 19 - In the abrasive surface layer of polyphenylene-A, LaMgAl 11 O 19 The mass ratio of polystyrene to A is 70~85:3~10:10~30.

5. The wear-resistant / environmental barrier composite gradient coating according to claim 1, characterized in that: The thickness of the Si bonding substrate is 50~150 μm; the thickness of the Yb2Si2O7-S environmental barrier intermediate layer is 30~80 μm; the thickness of the Yb2SiO5-S environmental barrier intermediate layer is 30~80 μm; the thickness of the LaMgAl 11 O 19 The thickness of the abrasive surface layer of polyphenylene-A is 300~800 μm; the total thickness of the abrasive / environmental barrier composite gradient coating is 400~1100 μm.

6. A method for preparing a wearable / environmental barrier composite gradient coating as described in any one of claims 1 to 5, characterized in that, Includes the following steps: (1) For SiC f / SiC CMCs matrix undergoes pretreatment including grinding, roughening, cleaning, and drying; (2) Atmospheric plasma spraying process is adopted for SiC f / SiC CMCs substrate surface sequentially deposited Si bonding underlayer, Yb2Si2O7-S environmental barrier intermediate layer, Yb2SiO5-S environmental barrier intermediate layer, LaMgAl 11 O 19 - Polyphenylene-A abrasive surface layer; to obtain a composite gradient coating; (3) Heat treatment is performed on the composite gradient coating to complete the formation of the porous structure and self-healing effect of the coating, and a wearable / environmental barrier composite gradient coating is obtained.

7. The method for preparing the abrasive / environmental barrier composite gradient coating according to claim 6, characterized in that: In step (1), a 240-400 mesh diamond grinding wheel is used to grind SiC. f The edges of the SiC CMCs substrate are mechanically ground to form a 30°~60° chamfer; the ground SiC is then subjected to dry sandblasting. f The SiC CMCs substrate surface was roughened by sandblasting to a surface roughness Ra > 5 μm. The sandblasting medium was 100-200 mesh corundum abrasive, the sandblasting pressure was 0.2-0.4 MPa, and the sandblasting time was 10-30 s. Anhydrous ethanol was used to treat the sandblasted SiC. f The SiC CMCs matrix was ultrasonically cleaned for 2-3 minutes; the cleaned SiC... f The SiC CMCs matrix was subjected to constant temperature drying treatment at a temperature of 80~120 ℃ for 5~10 h.

8. The method for preparing the abrasive / environmental barrier composite gradient coating according to claim 6, characterized in that: In step (2), before coating deposition, a plasma flow is used to process SiC. f The SiC CMCs substrate is preheated to a surface temperature of 400~600 ℃.

9. The method for preparing the abrasive / environmental barrier composite gradient coating according to claim 6, characterized in that: In step (2), during the Si bonding underlayer deposition process, argon and hydrogen are used as working gases, with an argon flow rate of 30-40 NLPM, a hydrogen flow rate of 10-15 NLPM, a spraying power of 25-35 kW, a spraying distance of 80-100 mm, a powder feed rate of 3%-6%, and a Si powder particle size of 10-60 μm; during the Yb2Si2O7-S environmental barrier intermediate layer deposition process, argon and hydrogen are used as working gases, with an argon flow rate of 25-35 NLPM, a hydrogen flow rate of 8-12 NLPM, a spraying power of 30-40 kW, a spraying distance of 100-120 mm, a powder feed rate of 5%-10%, and a Yb2Si2O7-S composite powder particle size of 30-130 μm; during the Yb2SiO5-S environmental barrier intermediate layer deposition process, argon and hydrogen are used as working gases, with an argon flow rate of 25-35 NLPM. NLPM, hydrogen flow rate of 8~12 NLPM, spraying power of 30~40 kW, spraying distance of 100~120 mm, powder feed rate of 5%~10%, Yb2SiO5-S composite powder particle size of 30~130 μm; LaMgAl 11 O 19 During the deposition of the polystyrene-A abrasive surface layer, argon and hydrogen are used as working gases. The argon flow rate is 30~40 NLPM, the hydrogen flow rate is 10~15 NLPM, the spraying power is 25~35 kW, the spraying distance is 100~150 mm, and the powder feed rate is 10%~20%. (LaMgAl) 11 O 19 The particle size of the polyphenylene-A composite powder is 40~130 μm.

10. The method for preparing the abrasive / environmental barrier composite gradient coating according to claim 6, characterized in that, In step (3), the coating is subjected to segmented heat treatment in an air atmosphere. The steps include: 1) Increase the temperature from room temperature to 500-600℃ at a rate of 5-10℃ / min, and maintain the temperature for 1-3 hours; 2) Then raise the temperature to 1000-1200 ℃ at a rate of 3-5 ℃ / min and keep it at that temperature for 5-10 h.

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