Self-healing LaMgAl11O19-based high-temperature abradable sealing coating and preparation method thereof

Abstract

The invention discloses a self-healing LaMgAl11O19-based high-temperature abradable sealing coating and a preparation method of the self-healing LaMgAl11O19-based high-temperature abradable sealing coating, and belongs to the technical field of ceramic-based coatings. The self-healing LaMgAl11O19-based high-temperature abradable sealing coating disclosed by the invention comprises a ceramic-based phase, a self-healing phase and a pore-forming phase, the mass ratio of the ceramic base phase to the self-healing phase to the pore-forming phase is (70-84): (10-20): (2-10); wherein the ceramic base phase is LaMgAl11O19, the self-healing phase is Ti3AlC2 or Ti2AlC, and the pore-forming phase is one of polybenzoate, starch and spherical graphite. The hardness and the strength of the high-temperature ceramic-based abradable sealing coating are balanced, the self-healing LaMgAl11O19-based composite powder can be obtained by adopting ball milling, stirring and granulation procedures in the preparation mode, adhesion and self-healing of the material on the surface of a base body are achieved by combining thermal spraying and heat treatment, and the method has the advantages of being simple and capable of achieving large-scale production, and is suitable for large-scale production of the high-temperature ceramic-based abradable sealing coating. Good application prospects are realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ceramic-based coating, and particularly relates to a self-healing LaMgAl 11 O 19 high-temperature abradable sealing coating and a preparation method thereof. BACKGROUND

[0002] High thrust-to-weight ratio, high efficiency and low fuel consumption have become the key targets of advanced aero-engine design and manufacturing, and the tip clearance between the turbine rotor blade and the turbine outer ring is an important factor affecting the performance of the engine. Excessive clearance will cause high-temperature gas leakage at the tip, directly causing energy loss and efficiency decay. While too small clearance may cause severe friction or even collision between the high-speed rotating blade and the turbine outer ring due to the blade elongation deformation and component vibration displacement caused by the machining tolerance, assembly deviation, and thermal expansion, etc. during engine manufacturing and operation, forming a serious safety hazard.

[0003] To alleviate the blade scuffing damage, a high-temperature resistant ceramic-based abradable sealing coating (ASC) is usually prepared on the inner wall surface of the turbine outer ring, which can realize tip clearance control through the active sacrifice and preferential wear of the coating, reducing gas leakage and improving engine efficiency, which requires the ASC to have a lower hardness. Based on the research foundation of thermal barrier coatings (TBCs), the porous yttria-stabilized zirconia (YSZ) coating prepared by atmospheric plasma spray (APS) is widely used in the field of ceramic-based ASCs below 1200 ℃ due to its high fracture toughness, low thermal conductivity and low elastic modulus. With the continuous increase of the working temperature of the turbine outer ring, high-temperature abradable materials suitable for 1300 ℃ and above have become the current research hotspot.

[0004] To reduce the hardness of ASCs (Abrasive Stainless Steel), polystyrene is typically used as a pore-forming phase, combined with a low-energy spraying process to create a porous, easily wearable structure. For example, Chinese invention patent CN108950454A discloses a high-temperature ceramic-based wearable sealing coating structure and its preparation method. The coating structure includes a NiCoCrAlTaY high-temperature anti-oxidation material bottom layer sequentially stacked on the surface of a high-temperature alloy turbine outer ring component substrate, and a top layer composed of a mixture of three materials: Sc2O3 and Y2O3 binary rare earth oxide co-doped ZrO2 material, CaF2 material, and polystyrene material. In the top layer material, polystyrene serves as the pore-forming material, and CaF2 is a high-temperature friction-reducing self-lubricating ceramic material. This high-temperature ceramic-based wearable sealing coating can be applied to the sealing of high-pressure turbine gas passages in aero-engines and ground-based gas turbines, with an operating temperature reaching 1300 ℃, meeting the requirements for sealing high-pressure turbine gas passages in advanced aero-engines and ground-based gas turbines. For example, Chinese invention patent CN116732460A provides a method for Hf6Ta2O. 17 A wear-resistant sealing coating and its preparation method are disclosed. The coating comprises a nickel-based high-temperature alloy substrate, a transition layer, and a ceramic layer stacked together. It features high service temperature, resistance to cracking and peeling, simple preparation process, low wear, and good thermal shock resistance.

[0005] However, these measures introduce several serious problems to coating strength: the difficulty in uniformly dispersing the porous phase of polyphenylene oxide leads to the formation of interconnected pore networks within the coating; ceramic coatings prepared by the APS process typically contain amorphous phases, and the volume shrinkage accompanying recrystallization at high temperatures can cause crack formation, thereby exacerbating structural degradation; low-energy spraying results in insufficient flattening of molten droplet particles, and the presence of a large number of unmelted particles further weakens the coating strength. These defects not only cause early coating failure but also increase the risk of coating chipping and detachment during scraping due to the inherent brittleness of ceramic materials. Therefore, achieving an effective balance between hardness and strength has become a key challenge for high-temperature ceramic-based ASCs. Summary of the Invention

[0006] In view of the above-mentioned deficiencies of the prior art, in a first aspect of the present invention, a self-healing LaMgAl that balances the hardness and strength of high-temperature ceramic-based Ascorbates (ASCs) and has a simple post-processing capability is provided. 11 O 19 The high-temperature wear-resistant sealing coating comprises: a ceramic matrix phase, a self-healing phase, and a pore-forming phase; by mass ratio, the ratio of ceramic matrix phase: self-healing phase: pore-forming phase is 70~84:10~20:2~10; wherein, the ceramic matrix phase is LaMgAl 11 O 19 The self-healing phase is Ti3AlC2 or Ti2AlC, and the pore-forming phase is one of polyphenylene ester, starch, or spherical graphite.

[0007] Preferably, the LaMgAl 11 O 19 The raw materials for its preparation include La2O3, MgO, and Al2O3, with a molar ratio of La2O3:MgO:Al2O3 = 1:2:11.

[0008] In a second aspect of the invention, a self-healing LaMgAl solution with a simple process and suitable for large-scale production is provided. 11 O 19 The preparation method of the high-temperature wear-resistant sealing coating includes the following steps: (1) Prepare raw materials according to the proportions; mix La2O3, MgO and Al2O3 powders, ball mill and dry to obtain a uniformly mixed powder; sinter and crush the uniformly mixed powder to obtain LaMgAl 11 O 19 Ceramic powder; (2) LaMgAl 11 O 19 Ceramic powder is mixed with a self-healing phase, binder, and dispersant, and ball-milled to form a homogeneous suspension. This suspension is then mixed with a pore-forming phase and stirred to obtain a homogeneous slurry. The homogeneous slurry is then spray-granulated, dried, and sieved to obtain the self-healing LaMgAl. 11 O 19 Base composite powder; (3) Self-healing LaMgAl 11 O 19 The composite powder is deposited on the substrate surface using thermal spraying technology to form LaMgAl 11 O 19 Base wear-resistant sealing coating; (4) LaMgAl 11 O 19 A self-healing LaMgAl coating was obtained by heat treatment of a wear-resistant sealing coating. 11 O 19 High-temperature wear-resistant sealing coating.

[0009] The desired coating structure can be obtained by using the above-mentioned differentiated mixing methods. The self-healing phase is mixed by ball milling, which can significantly improve the dispersion uniformity of the self-healing phase, while the pore-forming phase is mixed by stirring, which can effectively maintain the size of the pore-forming phase, thereby forming coarse pores of the corresponding size.

[0010] Preferably, in step (1), the ball milling speed is 100~200 rpm, the ball milling time is 20~30 h; the drying temperature is 80~120 ℃, the drying time is 10~15 h; the sintering temperature is 1400~1600 ℃, the sintering time is 12~24 h; after crushing, LaMgAl 11 O 19The particle size of the ceramic powder is 10~100 μm.

[0011] Preferably, in step (1) or step (2), the ball milling media are deionized water and zirconia balls, with a water-to-powder mass ratio of 1~2:1 and a ball-to-powder mass ratio of 2~3:1.

[0012] Preferably, in step (2), the uniformly mixed slurry contains, by mass ratio, LaMgAl 11 O 19 Self-healing phase: Pore-forming phase: Binder: Dispersant = 70~84:10~20:2~10:2~4:0.5~1.5.

[0013] Preferably, in step (2), the powder particle size of the self-healing phase is 50~150 μm, and the powder particle size of the pore-forming phase is 20~50 μm.

[0014] When using the self-healing phase and pore-forming phase with the above-mentioned powder particle size, a self-healing LaMgAl with good mechanical properties can be formed. 11 O 19 Base wear-resistant sealing coating.

[0015] Preferably, in step (2), the binder is one of gum arabic, polyvinyl alcohol, and carboxymethyl cellulose, and the dispersant is one of ammonium citrate, polyethylene glycol, and triethanolamine.

[0016] Preferably, in step (2), the ball milling speed is 100~200 rpm and the ball milling time is 70~80 h; the stirring speed is 120~150 rpm and the stirring time is 4~6 h.

[0017] Preferably, in step (2), a spray dryer is used for spray granulation. The inlet temperature of the spray dryer is 200~240 ℃, the outlet temperature is 100~130 ℃, and the atomizer speed is 20~25 Hz.

[0018] Preferably, in step (2), the drying temperature is 60~80 ℃ and the drying time is 10~15 h; the sieved self-healing LaMgAl 11 O 19 The particle size of the composite powder is 30~130 μm.

[0019] Preferably, in step (3), the thermal spraying technology is atmospheric plasma spraying, the spraying power is 25~35 kW, the spraying distance is 100~150 mm, the powder feeding rate is 10%~20%, and the coating thickness is not less than 0.3 mm.

[0020] Preferably, in step (3), argon and hydrogen are used as working gases, with an argon flow rate of 30~40 nlpm and a hydrogen flow rate of 10~15 nlpm.

[0021] LaMgAl prepared using the above spraying process parameters 11 O 19 The wear-resistant sealing coating has good mechanical properties.

[0022] Preferably, in step (4), the heat treatment process is as follows: the temperature is increased from room temperature to 500-600 ℃ at a rate of 5-10 ℃ / min and held for 1-3 h to remove the pore-forming phase in the coating and form the target porous structure; then the temperature is increased to 1000-1200 ℃ at a rate of 3-5 ℃ / min and held for 5-10 h, with the heat treatment atmosphere being air, thereby achieving self-healing of the coating.

[0023] The segmented heat treatment process described above can effectively improve the uniformity of the coating pore structure and the integrity of crack repair.

[0024] Based on the above technical solutions, the design concept and principle of this invention are as follows: The LaMgAl used in this invention 11 O 19 As a ceramic matrix phase, it exhibits excellent thermal stability up to 1600 °C, and its dense coating has a thermal conductivity as low as 1.5~1.9 W / m·K. The porous design of this invention further reduces the thermal conductivity, thereby providing effective thermal insulation protection for the matrix. LaMgAl 11 O 19 The unique lamellar crystal structure reduces heat conduction through interlayer phonon scattering, while simultaneously endowing the coating with excellent anti-sintering ability and thermal shock resistance. The self-healing phase design utilizes MAX phase materials that exhibit oxidation-induced crack healing capabilities at high temperatures. This invention selects Ti3AlC2 or Ti2AlC as the self-healing phase for the ceramic-based wearable sealing coating. In a high-temperature environment, the self-healing phase Ti3AlC2 or Ti2AlC oxidizes to generate TiO2 and Al2O3. Accompanied by a 50%–60% volume expansion, under compressive stress, it promotes crack closure, thereby achieving damage self-repair. Furthermore, on one hand, the self-healing phase not only endows the coating with self-healing function; on the other hand, among the formed oxidation products, Al2O3 has good airtightness, effectively blocking oxygen penetration, while TiO2 acts as a sintering aid, designed to enter LaMgAl through solid solution. 11 O 19 The formation of cation vacancy defects in the crystal lattice significantly enhances the ion diffusion rate within the lattice and effectively reduces the LaMgAl content. 11 O 19Sintering activation energy. This process promotes grain growth and bonding between unmelted particles, driving the transformation of interconnected pores within the coating into a closed-pore structure, thereby improving coating strength. The pore-forming phase uses materials that are easily decomposed and volatilized at high temperatures, and whose decomposition products do not negatively affect coating performance, such as polystyrene, starch, and spherical graphite. When the ceramic matrix phase, self-healing phase, and pore-forming phase are combined in the above proportions, an effective balance between coating hardness and strength is achieved. Self-healing can be achieved simply by heat treatment at high temperatures, resulting in a simple post-processing capability and excellent overall performance.

[0025] Compared with the prior art, the present invention has the following advantages and beneficial effects: This invention provides a self-healing LaMgAl 11 O 19 High-temperature abrasion-resistant sealing coating, with LaMgAl 11 O 19 As a ceramic matrix phase, Ti3AlC2 or Ti2AlC acts as a self-healing phase. The volume expansion accompanying the oxidation process of Ti3AlC2 or Ti2AlC repairs cracks, and its oxidation products promote the sintering process, thereby eliminating unmelted particles and promoting the transformation of interconnected pores into closed-pore structures, thus playing a dual role. This coating balances the hardness and strength of high-temperature ceramic matrix ASCs and has good application prospects.

[0026] This invention provides a self-healing LaMgAl 11 O 19 A method for preparing a high-temperature wear-resistant sealing coating involves a ball milling-stirring-granulation process to obtain a self-healing LaMgAl coating. 11 O 19 The composite powder, combined with thermal spraying and heat treatment, achieves material adhesion and self-healing on the substrate surface, and has the advantages of simple method and large-scale production. Attached Figure Description

[0027] Figure 1 The self-healing LaMgAl prepared in this invention 11 O 19 A schematic diagram of the structure of a high-temperature wear-resistant sealing coating; Figure 2 The self-healing LaMgAl prepared in Example 1 of this invention 11 O 19 Microscopic morphology images of the composite powder; among which, Figure 2 (a) is a 200× low-magnification image. Figure 2 (b) is a 1000× high-magnification image; Figure 3 The self-healing LaMgAl prepared in Example 1 of this invention 11 O 19Elemental distribution diagram of the composite powder; Figure 4 The sprayed LaMgAl prepared by atmospheric plasma spraying technology in Example 5 of this invention is shown. 11 O 19 Microscopic morphology images of the wear-resistant sealing coating; among which, Figure 4 (a) is a microscopic image of the coating surface. Figure 4 (b) is a microscopic morphology image of the coating cross-section; Figure 5 The self-healing LaMgAl obtained by heat treatment in Example 5 of this invention. 11 O 19 Microscopic morphology images of the wear-resistant sealing coating; among which, Figure 5 (a) is a microscopic image of the coating surface. Figure 5 (b) is a microscopic morphology image of the coating cross-section; Figure 6 The self-healing LaMgAl obtained by heat treatment in Example 2 of this invention 11 O 19 X-ray diffraction (XRD) pattern of the wearable sealant coating. Detailed Implementation

[0028] 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.

[0029] In the following embodiments: The La2O3 raw material was purchased from Hunan Rare Earth Metal Materials Research Institute Co., Ltd., with a purity of 99.99%. MgO, gum arabic, polyvinyl alcohol, carboxymethyl cellulose, ammonium citrate, polyethylene glycol, and triethanolamine were purchased from Sinopharm Chemical Reagent Co., Ltd., with a purity of 99.99%. The Al2O3 raw material was purchased from China Aluminum Zhengzhou Nonferrous Metals Research Institute Co., Ltd., with a purity of 99.99%. Ti3AlC2, Ti2AlC, starch, and spherical graphite raw materials were purchased from Forsmann Technology (Beijing) 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%.

[0030] Example 1 This embodiment provides a self-healing LaMgAl 11 O 19 The high-temperature wear-resistant sealing coating has the following structure: Figure 1As shown. The coating comprises 84 g of a ceramic matrix phase, 20 g of a self-healing phase, and 10 g of a pore-forming phase; the ceramic matrix phase is LaMgAl. 11 O 19 Its raw materials include: 6 g of La2O3, 12 g of MgO, and 66 g of Al2O3; the self-healing phase is Ti3AlC2; and the pore-forming phase is polyphenylene ester.

[0031] In this embodiment, the self-healing LaMgAl 11 O 19 The preparation method of the high-temperature wear-resistant sealing coating is as follows: (1) 6 g of La2O3 powder, 12 g of MgO powder, and 66 g of Al2O3 powder were mixed and ball-milled at 150 rpm for 24 h to obtain a uniform powder mixture. The ball milling media were deionized water and zirconia balls, with a water-to-powder mass ratio of 1:1 and a ball-to-powder mass ratio of 2:1. The uniform powder mixture was placed in an oven and dried at 100 ℃ for 12 h to obtain a uniform powder mixture. The uniform powder mixture was placed in a high-temperature box furnace and sintered at 1500 ℃ for 24 h, followed by crushing to obtain LaMgAl with a particle size of 20~80 μm. 11 O 19 ceramic powder (2) Take the 84 g of LaMgAl obtained in step (1) 11 O 19 Ceramic powder was mixed with 20 g of Ti3AlC2 self-healing phase with a particle size of 80-120 μm, 3 g of gum arabic binder, and 1 g of ammonium citrate dispersant. The mixture was ball-milled at 150 rpm for 72 h to obtain a homogeneous suspension. The ball-milling media consisted of deionized water and zirconia balls, with a water-to-powder mass ratio of 1:1 and a ball-to-powder mass ratio of 2:1. The homogeneous suspension was then mixed with 10 g of polystyrene pore-forming phase with a particle size of 25-45 μm and stirred at 120 rpm for 5 h to obtain a homogeneous slurry. This homogeneous slurry was then spray-granulated, dried, and sieved to obtain self-healing LaMgAl. 11 O 19 The base composite powder was prepared by spray drying at an inlet temperature of 220 ℃, an outlet temperature of 120 ℃, an atomizer speed of 22 Hz, a drying temperature of 70 ℃, and a drying time of 12 h. The sieved self-healing LaMgAl... 11 O 19 The particle size of the composite powder is 40~120 μm; (3) The self-healing LaMgAl obtained in step (2) 11 O19 The composite powder is deposited on the substrate surface using atmospheric plasma spraying technology to form LaMgAl 11 O 19 The wear-resistant sealing coating has a spraying power of 30 kW, a spraying distance of 120 mm, a powder feeding rate of 15%, and a coating thickness of 0.4 mm. Argon and hydrogen are used as working gases, with an argon flow rate of 35 nlpm and a hydrogen flow rate of 12 nlpm. (4) Take the LaMgAl obtained in step (3) 11 O 19 The wear-resistant sealing coating was placed in a high-temperature box furnace and heat-treated in air atmosphere. The process involved raising the temperature from room temperature to 550 °C at a rate of 8 °C / min and holding for 1 h, followed by raising the temperature to 1200 °C at a rate of 4 °C / min and holding for 5 h, thus obtaining the self-healing LaMgAl. 11 O 19 Base wear-resistant sealing coating.

[0032] Example 2 This embodiment provides a self-healing LaMgAl 11 O 19 The high-temperature wear-resistant sealing coating has the following structure: Figure 1 As shown. The coating comprises 70 g of a ceramic matrix phase, 10 g of a self-healing phase, and 5 g of a pore-forming phase; the ceramic matrix phase is LaMgAl. 11 O 19 Its raw materials include: 5 g of La2O3, 10 g of MgO, and 55 g of Al2O3; the self-healing phase is Ti2AlC; and the pore-forming phase is polyphenylene ester.

[0033] In this embodiment, the self-healing LaMgAl 11 O 19 The preparation method of the high-temperature wear-resistant sealing coating is as follows: (1) 5 g of La2O3 powder, 10 g of MgO powder, and 55 g of Al2O3 powder were mixed and ball-milled at 120 rpm for 20 h to obtain a uniform powder mixture. The ball milling media were deionized water and zirconia balls, with a water-to-powder mass ratio of 1.5:1 and a ball-to-powder mass ratio of 2.5:1. The uniform powder mixture was placed in an oven and dried at 110 ℃ for 10 h to obtain a uniform powder mixture. The uniform powder mixture was placed in a high-temperature box furnace and sintered at 1600 ℃ for 20 h, followed by crushing to obtain LaMgAl with a particle size of 30~90 μm. 11 O 19 ceramic powder (2) Take 70 g of LaMgAl obtained in step (1) 11 O 19 Ceramic powder was mixed with 10 g of Ti₂AlC self-healing phase with a particle size of 60–100 μm, 2 g of polyvinyl alcohol binder, and 0.8 g of polyethylene glycol dispersant. The mixture was ball-milled at 120 rpm for 80 h to obtain a homogeneous suspension. The ball-milling media consisted of deionized water and zirconia balls, with a water-to-powder mass ratio of 1.5:1 and a ball-to-powder mass ratio of 2.5:1. The homogeneous suspension was then mixed with 5 g of polystyrene pore-forming phase with a particle size of 20–40 μm and stirred at 130 rpm for 4 h to obtain a homogeneous slurry. This homogeneous slurry was then spray-granulated, dried, and sieved to obtain self-healing LaMgAl₂O₃. 11 O 19 The base composite powder was prepared by spray drying at an inlet temperature of 230 ℃, an outlet temperature of 125 ℃, an atomizer speed of 23 Hz, a drying temperature of 80 ℃, and a drying time of 10 h. The sieved self-healing LaMgAl... 11 O 19 The particle size of the composite powder is 45~110 μm; (3) The self-healing LaMgAl obtained in step (2) 11 O 19 The composite powder is deposited on the substrate surface using atmospheric plasma spraying technology to form LaMgAl 11 O 19 The wear-resistant sealing coating has a spraying power of 32 kW, a spraying distance of 110 mm, a powder feeding rate of 12%, and a coating thickness of 0.5 mm. Argon and hydrogen are used as working gases, with an argon flow rate of 38 nlpm and a hydrogen flow rate of 14 nlpm. (4) Take the LaMgAl obtained in step (3) 11 O 19 The wear-resistant sealing coating was placed in a high-temperature box furnace and heat-treated in air atmosphere. The process involved raising the temperature from room temperature to 500 °C at a rate of 7 °C / min and holding for 1 h, followed by raising the temperature to 1100 °C at a rate of 3 °C / min and holding for 8 h, thus obtaining the self-healing LaMgAl. 11 O 19 Base wear-resistant sealing coating.

[0034] Example 3 This embodiment provides a self-healing LaMgAl 11 O 19 The high-temperature wear-resistant sealing coating has the following structure: Figure 1As shown. The coating comprises 77 g of a ceramic matrix phase, 15 g of a self-healing phase, and 7 g of a pore-forming phase; the ceramic matrix phase is LaMgAl. 11 O 19 The raw materials include: 5.5 g of La2O3, 11 g of MgO, and 60.5 g of Al2O3; the self-healing phase is Ti3AlC2; and the pore-forming phase is starch.

[0035] In this embodiment, the self-healing LaMgAl 11 O 19 The preparation method of the high-temperature wear-resistant sealing coating is as follows: (1) 5.5 g of La2O3 powder, 11 g of MgO powder, and 60.5 g of Al2O3 powder were mixed and ball-milled at 200 rpm for 20 h to obtain a uniform powder mixture. The ball milling media were deionized water and zirconia balls, with a water-to-powder mass ratio of 2:1 and a ball-to-powder mass ratio of 3:1. The uniform powder mixture was placed in an oven and dried at 120 ℃ for 10 h to obtain a uniform powder mixture. The uniform powder mixture was placed in a high-temperature box furnace and sintered at 1400 ℃ for 24 h, followed by crushing to obtain LaMgAl with a particle size of 40~100 μm. 11 O 19 Ceramic powder; (2) Take the 77 g of LaMgAl obtained in step (1) 11 O 19 Ceramic powder was mixed with 15 g of Ti3AlC2 self-healing phase with a particle size of 70-130 μm, 2.5 g of carboxymethyl cellulose binder, and 1 g of triethanolamine dispersant. The mixture was ball-milled at 200 rpm for 70 h to obtain a homogeneous suspension. The ball-milling media consisted of deionized water and zirconia balls, with a water-to-powder mass ratio of 2:1 and a ball-to-powder mass ratio of 3:1. The homogeneous suspension was then mixed with 7 g of starch pore-forming phase with a particle size of 30-50 μm and stirred at 150 rpm for 5 h to obtain a homogeneous slurry. This homogeneous slurry was then spray-granulated, dried, and sieved to obtain self-healing LaMgAl. 11 O 19 The base composite powder was prepared by spray drying at an inlet temperature of 240 ℃, an outlet temperature of 130 ℃, an atomizer speed of 25 Hz, a drying temperature of 60 ℃, and a drying time of 15 h. The sieved self-healing LaMgAl... 11 O 19 The particle size of the composite powder is 50~130 μm; (3) The self-healing LaMgAl obtained in step (2)11 O 19 The composite powder is deposited on the substrate surface using atmospheric plasma spraying technology to form LaMgAl 11 O 19 The abrasive sealing coating has a spraying power of 25 kW, a spraying distance of 100 mm, a powder feeding rate of 10%, and a coating thickness of 0.4 mm. Argon and hydrogen are used as working gases, with an argon flow rate of 30 nlpm and a hydrogen flow rate of 10 nlpm. (4) Take the LaMgAl obtained in step (3) 11 O 19 The wear-resistant sealing coating was placed in a high-temperature box furnace and heat-treated in air atmosphere. The process involved raising the temperature from room temperature to 600 °C at a rate of 10 °C / min and holding for 2 hours, followed by raising the temperature to 1000 °C at a rate of 5 °C / min and holding for 10 hours, thus obtaining the self-healing LaMgAl. 11 O 19 Base wear-resistant sealing coating.

[0036] Example 4 This embodiment provides a self-healing LaMgAl 11 O 19 The high-temperature wear-resistant sealing coating has the following structure: Figure 1 As shown. The coating comprises 84 g of a ceramic matrix phase, 10 g of a self-healing phase, and 5 g of a pore-forming phase; the ceramic matrix phase is LaMgAl. 11 O 19 Its raw materials include: 6 g of La2O3, 12 g of MgO, and 66 g of Al2O3; the self-healing phase is Ti2AlC; and the pore-forming phase is spherical graphite.

[0037] In this embodiment, the self-healing LaMgAl 11 O 19 The preparation method of the high-temperature wear-resistant sealing coating is as follows: (1) 6 g of La2O3 powder, 12 g of MgO powder, and 66 g of Al2O3 powder were mixed and ball-milled at 160 rpm for 30 h to obtain a uniform powder mixture. The ball milling media were deionized water and zirconia balls, with a water-to-powder mass ratio of 1:1 and a ball-to-powder mass ratio of 2:1. The uniform powder mixture was placed in an oven and dried at 80 ℃ for 15 h to obtain a uniform powder mixture. The uniform powder mixture was placed in a high-temperature box furnace and sintered at 1500 ℃ for 20 h, followed by crushing to obtain LaMgAl with a particle size of 10~70 μm. 11 O 19 Ceramic powder; (2) Take the 84 g of LaMgAl obtained in step (1) 11 O 19 Ceramic powder was mixed with 10 g of Ti₂AlC self-healing phase with a particle size of 70–150 μm, 4 g of gum arabic binder, and 1.5 g of ammonium citrate dispersant. The mixture was ball-milled at 160 rpm for 75 h to obtain a homogeneous suspension. The ball-milling media consisted of deionized water and zirconia balls, with a water-to-powder mass ratio of 1:1 and a ball-to-powder mass ratio of 2:1. The homogeneous suspension was then mixed with 5 g of spherical graphite porous phase with a particle size of 20–45 μm and stirred at 140 rpm for 4 h to obtain a homogeneous slurry. This homogeneous slurry was then spray-granulated, dried, and sieved to obtain self-healing LaMgAl₂O₃. 11 O 19 The base composite powder was prepared by spray drying at an inlet temperature of 210 ℃, an outlet temperature of 115 ℃, an atomizer speed of 21 Hz, a drying temperature of 60 ℃, and a drying time of 15 h. The sieved self-healing LaMgAl... 11 O 19 The particle size of the composite powder is 30~110 μm; (3) The self-healing LaMgAl obtained in step (2) 11 O 19 The composite powder is deposited on the substrate surface using atmospheric plasma spraying technology to form LaMgAl 11 O 19 The wear-resistant sealing coating has a spraying power of 35 kW, a spraying distance of 150 mm, a powder feeding rate of 20%, and a coating thickness of 0.5 mm. Argon and hydrogen are used as working gases, with an argon flow rate of 40 nlpm and a hydrogen flow rate of 15 nlpm. (4) Take the LaMgAl obtained in step (3) 11 O 19 The wear-resistant sealing coating was placed in a high-temperature box furnace and heat-treated in air atmosphere. The process involved raising the temperature from room temperature to 600 °C at a rate of 6 °C / min and holding for 3 h, followed by raising the temperature to 1100 °C at a rate of 3 °C / min and holding for 8 h, thus obtaining the self-healing LaMgAl. 11 O 19 Base wear-resistant sealing coating.

[0038] Example 5 This embodiment provides a self-healing LaMgAl 11 O 19 The high-temperature wear-resistant sealing coating has the following structure: Figure 1As shown. The coating comprises 77 g of a ceramic matrix phase, 12 g of a self-healing phase, and 7 g of a pore-forming phase; the ceramic matrix phase is LaMgAl. 11 O 19 Its raw materials include: 5.5 g of La2O3, 11 g of MgO, and 60.5 g of Al2O3; the self-healing phase is Ti3AlC2; and the pore-forming phase is polyphenylene ester.

[0039] In this embodiment, the self-healing LaMgAl 11 O 19 The preparation method of the high-temperature wear-resistant sealing coating is as follows: (1) 5.5 g of La2O3 powder, 11 g of MgO powder, and 60.5 g of Al2O3 powder were mixed and ball-milled at 100 rpm for 28 h to obtain a uniform powder mixture. The ball milling media were deionized water and zirconia balls, with a water-to-powder mass ratio of 1.5:1 and a ball-to-powder mass ratio of 2.5:1. The uniform powder mixture was placed in an oven and dried at 90 ℃ for 14 h to obtain a uniform powder mixture. The uniform powder mixture was placed in a high-temperature box furnace and sintered at 1600 ℃ for 12 h, followed by crushing to obtain LaMgAl with a particle size of 30~80 μm. 11 O 19 Ceramic powder; (2) Take the 77 g of LaMgAl obtained in step (1) 11 O 19 Ceramic powder was mixed with 12 g of Ti3AlC2 self-healing phase with a particle size of 50-130 μm, 2 g of carboxymethyl cellulose binder, and 0.5 g of polyethylene glycol dispersant. The mixture was ball-milled at 100 rpm for 80 h to obtain a homogeneous suspension. The ball-milling media consisted of deionized water and zirconia balls, with a water-to-powder mass ratio of 1.5:1 and a ball-to-powder mass ratio of 2.5:1. The homogeneous suspension was then mixed with 7 g of polystyrene pore-forming phase with a particle size of 20-50 μm and stirred at 120 rpm for 6 h to obtain a homogeneous slurry. This homogeneous slurry was then spray-granulated, dried, and sieved to obtain self-healing LaMgAl. 11 O 19 The base composite powder was prepared by spray drying at an inlet temperature of 200 ℃, an outlet temperature of 100 ℃, an atomizer speed of 20 Hz, a drying temperature of 80 ℃, and a drying time of 10 h. The sieved self-healing LaMgAl... 11 O 19 The particle size of the composite powder is 30~130 μm; (3) The self-healing LaMgAl obtained in step (2) 11 O 19 The composite powder is deposited on the substrate surface using atmospheric plasma spraying technology to form LaMgAl 11 O 19 The abrasive sealing coating has a spraying power of 28 kW, a spraying distance of 130 mm, a powder feeding rate of 10%, and a coating thickness of 0.6 mm. Argon and hydrogen are used as working gases, with an argon flow rate of 30 nlpm and a hydrogen flow rate of 10 nlpm. (4) Take the LaMgAl obtained in step (3) 11 O 19 The wear-resistant sealing coating was placed in a high-temperature box furnace and heat-treated in air atmosphere. The process involved raising the temperature from room temperature to 550 °C at a rate of 5 °C / min and holding for 2 hours, followed by raising the temperature to 1000 °C at a rate of 3 °C / min and holding for 10 hours, thus obtaining the self-healing LaMgAl. 11 O 19 Base wear-resistant sealing coating.

[0040] Comparative Example 1 This comparative example is basically the same as Example 1, except that: no self-healing phase was added in step (2) of Comparative Example 1, and LaMgAl without a self-healing phase was obtained after step (4). 11 O 19 Base wear-resistant sealing coating.

[0041] Test Example 1 To illustrate the self-healing mechanism relative to LaMgAl 11 O 19 The influence of the wear-resistant sealing coating on the mechanical properties of the heat-treated LaMgAl in Examples 1-5 and Comparative Example 1 11 O 19 The surface Rockwell hardness and bonding strength of the wear-resistant sealing coating were tested, and the test results are shown in Table 1.

[0042] Table 1: Surface Rockwell hardness and bond strength test results of the examples and comparative examples

[0043] As shown in Table 1, the coating bonding strength of Examples 1 to 5 is significantly improved by 30.4% to 62.5% compared with Comparative Example 1, while the surface Rockwell hardness only increases slightly by 1.7% to 13.5%, indicating that the present invention can obtain a high-temperature ceramic-based wearable sealing coating with good mechanical properties.

[0044] Test Example 2 The self-healing LaMgAl prepared in Example 1 of this invention 11 O19 The microstructure of the composite powder was observed, and the results are as follows: Figure 2 As shown. Among them. Figure 2 (a) is a 200× low-magnification image. Figure 2 (b) is a 1000× high-magnification image. The image shows that the self-healing LaMgAl... 11 O 19 The base composite powder is mainly an agglomerated powder, with some being coated powder. The coated powder uses high-temperature resistant ceramic fine particles as the outer shell and polystyrene coarse particles as the core, forming a core-shell structure, which protects the polystyrene pore-forming phase during the spraying process and reduces ablation loss.

[0045] The self-healing LaMgAl prepared in Example 1 of this invention 11 O 19 The elemental distribution of the composite powder was characterized, and the results are as follows: Figure 3 As shown. Based on Figure 3 As can be seen from the Ti element distribution diagram, the self-healing phase is uniformly distributed in the powder particles. Combined with... Figure 2 This demonstrates that the ball milling-stirring-granulation process can produce spray powder that meets the requirements, and it has the advantages of being simple, having low operating costs, and being suitable for industrial production.

[0046] Observe the sprayed LaMgAl prepared by atmospheric plasma spraying technology in Example 5. 11 O 19 The microstructure of the wear-resistant sealing coating is shown in the following figures. Figure 4 As shown. Among them, Figure 4 (a) is a microscopic image of the coating surface. Figure 4 (b) is a microscopic morphology image of the coating cross section. It can be seen from the figure that there are significant vertical cracks, horizontal cracks, and unmelted particle agglomeration defects in the sprayed coating, which will have a negative impact on the coating strength.

[0047] Figure 5 The self-healing LaMgAl obtained by heat treatment in Example 5 of this invention. 11 O 19 Microscopic morphology images of the wear-resistant sealing coating. Among them, Figure 5 (a) is a microscopic image of the coating surface. Figure 5 (b) shows the microstructure of the coating cross-section. The image reveals that cracks and unmelted particles completely disappear within the self-healing coating, with clearly defined grains and grain boundaries, and a large number of fine closed pores. This clearly demonstrates that the self-healing process of high-temperature heat treatment can effectively repair cracks, promote grain growth and bonding between unmelted particles, and drive the transformation of interconnected pores within the coating into a closed-pore structure, which is beneficial for improving coating strength.

[0048] XRD was used to analyze the self-healing LaMgAl obtained by heat treatment in Example 2. 11 O 19 The wear-resistant sealing coating has been characterized, and the XRD pattern is shown below. Figure 6 As shown. Figure 6 Phase analysis showed that, apart from the main phase LaMgAl, the coating contained... 11 O 19 In addition to the self-healing oxidation product TiO2, LaTi2Al9O also appeared. 19 Phase. This is because part of the LaMgAl during the spraying process... 11 O 19 The decomposition into LaAlO3 is caused by the subsequent reaction with the self-healing phase oxidation products Al2O3 and TiO2, leaving an excess of TiO2 phase.

[0049] In summary, the self-healing LaMgAl of the present invention 11 O 19 The high-temperature wear-resistant sealing coating, through its porous design, further reduces thermal conductivity and provides effective thermal insulation protection to the substrate. LaMgAl 11 O 19 The unique lamellar crystal structure reduces heat conduction through interlayer phonon scattering, endowing the coating with excellent sintering resistance and thermal shock resistance. In the self-healing phase, this invention selects Ti3AlC2 or Ti2AlC. In a high-temperature environment, the self-healing phase oxidizes to generate TiO2 and Al2O3. Accompanying volume expansion under compressive stress promotes crack closure, achieving damage self-repair. Furthermore, Al2O3 has good airtightness, effectively blocking oxygen penetration, while TiO2, as a sintering aid, enters LaMgAl through solid solution. 11 O 19 The formation of cation vacancy defects in the crystal lattice significantly enhances the ion diffusion rate within the lattice and effectively reduces the LaMgAl content. 11 O 19 Sintering activation energy. This process promotes grain growth and bonding between unmelted particles, driving the transformation of interconnected pores in the coating into a closed-pore structure, thus improving the coating strength. This invention achieves self-healing simply by heat-treating the coating at high temperatures, offering a simple post-processing capability; and self-healing LaMgAl can be obtained through conventional ball milling-stirring-granulation processes. 11 O 19 The basic composite powder has a simple preparation method, can be mass-produced, and has good application prospects.

[0050] 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 self-healing LaMgAl 11 O 19 The high-temperature wear-resistant sealing coating is characterized by, include: Ceramic matrix phase, self-healing phase, pore-forming phase; By mass ratio, the ratio of ceramic matrix phase: self-healing phase: pore-forming phase is 70~84:10~20:2~10; wherein, the ceramic matrix phase is LaMgAl 11 O 19 The self-healing phase is Ti3AlC2 or Ti2AlC, and the pore-forming phase is one of polyphenylene ester, starch, or spherical graphite.

2. The self-healing LaMgAl according to claim 1 11 O 19 The high-temperature wear-resistant sealing coating is characterized by: The LaMgAl 11 O 19 The raw materials for its preparation include La2O3, MgO, and Al2O3, with a molar ratio of La2O3:MgO:Al2O3 = 1:2:

11.

3. A self-healing LaMgAl as described in claim 1 or 2 11 O 19 A method for preparing a high-temperature wear-resistant sealing coating, characterized in that, Includes the following steps: (1) Prepare raw materials according to the proportions; mix La2O3, MgO and Al2O3 powders, ball mill and dry to obtain a uniform mixed powder; sinter and crush the uniform mixed powder to obtain LaMgAl 11 O 19 Ceramic powder; (2) LaMgAl 11 O 19 Ceramic powder is mixed with a self-healing phase, binder, and dispersant, and ball-milled to form a homogeneous suspension. This suspension is then mixed with a pore-forming phase and stirred to obtain a homogeneous slurry. The homogeneous slurry is then spray-granulated, dried, and sieved to obtain the self-healing LaMgAl. 11 O 19 Base composite powder; (3) Self-healing LaMgAl 11 O 19 The composite powder is deposited on the substrate surface using thermal spraying technology to form LaMgAl 11 O 19 Base wear-resistant sealing coating; (4) LaMgAl 11 O 19 A self-healing LaMgAl coating was obtained by heat treatment of a wear-resistant sealing coating. 11 O 19 High-temperature wear-resistant sealing coating.

4. The self-healing LaMgAl according to claim 3 11 O 19 A method for preparing a high-temperature wear-resistant sealing coating, characterized in that: In step (1), the ball milling speed is 100~200 rpm, the ball milling time is 20~30 h; the drying temperature is 80~120℃, the drying time is 10~15 h; the sintering temperature is 1400~1600 ℃, the sintering time is 12~24 h; after crushing, LaMgAl 11 O 19 The particle size of the ceramic powder is 10~100 μm.

5. The self-healing LaMgAl according to claim 3 11 O 19 A method for preparing a high-temperature wear-resistant sealing coating, characterized in that: In step (1) or step (2), the ball milling media are deionized water and zirconia balls, with a water-to-powder mass ratio of 1~2:1 and a ball-to-powder mass ratio of 2~3:

1.

6. The self-healing LaMgAl according to claim 3 11 O 19 A method for preparing a high-temperature wear-resistant sealing coating, characterized in that: In step (2), the uniformly mixed slurry contains, by mass ratio, LaMgAl 11 O 19 The self-healing phase: pore-forming phase: binder: dispersant ratio is 70~84:10~20:2~10:2~4:0.5~1.5; the powder particle size of the self-healing phase is 50~150 μm, and the powder particle size of the pore-forming phase is 20~50 μm; the binder is one of gum arabic, polyvinyl alcohol, and carboxymethyl cellulose, and the dispersant is one of ammonium citrate, polyethylene glycol, and triethanolamine.

7. The self-healing LaMgAl according to claim 3 11 O 19 A method for preparing a high-temperature wear-resistant sealing coating, characterized in that: In step (2), the ball milling speed is 100~200 rpm and the ball milling time is 70~80 h; the stirring speed is 120~150 rpm and the stirring time is 4~6 h.

8. The self-healing LaMgAl according to claim 3 11 O 19 A method for preparing a high-temperature wear-resistant sealing coating, characterized in that: In step (2), a spray dryer is used for spray granulation. The inlet temperature of the spray dryer is 200~240℃, the outlet temperature is 100~130℃, and the atomizer speed is 20~25 Hz. The drying temperature is 60~80℃, and the drying time is 10~15h. The sieved self-healing LaMgAl 11 O 19 The particle size of the composite powder is 30~130 μm.

9. The self-healing LaMgAl according to claim 3 11 O 19 A method for preparing a high-temperature wear-resistant sealing coating, characterized in that: In step (3), the thermal spraying technology is atmospheric plasma spraying, the spraying power is 25~35 kW, the spraying distance is 100~150 mm, the powder feeding rate is 10%~20%, and the coating thickness is not less than 0.3 mm; argon and hydrogen are used as working gases, the argon flow rate is 30~40 nlpm, and the hydrogen flow rate is 10~15 nlpm.

10. The self-healing LaMgAl according to claim 3 11 O 19 A method for preparing a high-temperature wear-resistant sealing coating, characterized in that, In step (4), the heat treatment process is as follows: the temperature is increased from room temperature to 500-600 ℃ at a rate of 5-10 ℃ / min and held for 1-3 h to remove the pore-forming phase in the coating and form the target porous structure; then the temperature is increased to 1000-1200 ℃ at a rate of 3-5 ℃ / min and held for 5-10 h, with air as the heat treatment atmosphere, thereby achieving self-healing of the coating.

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