Coating material, preparation method thereof and environmental barrier coating

Abstract

The invention relates to the field of thermal barrier materials, and discloses a coating material, a preparation method thereof and an environmental barrier coating. The chemical formula of the coating material is MAlO3, and M comprises at least one of Nd, Sm, Eu, Gd, Dy, Ho, Er, Yb and Lu. The coating material provided by the invention has excellent fracture toughness, relatively low thermal conductivity, relatively high thermal expansion coefficient and good CMAS corrosion resistance.

Description

Technical Field

[0001] The present application relates to the field of thermal barrier materials, and in particular, to coating materials and preparation methods thereof, and environmental barrier coatings. Background Art

[0002] Thermal barrier coating technology is one of the three key technologies for the preparation of high-performance aircraft engine and gas turbine blades. Thermal barrier coatings block turbine blades from high-temperature combustion gases to protect the blades from high-temperature, high-speed airflow and isolate heat conduction, thereby increasing the operating temperature and service life of aircraft engines and gas turbines. The service life of thermal barrier coatings is affected by their service environment, so they are often protected by providing an environmental barrier coating on their surface. For environmental barrier coatings, lower thermal conductivity, a thermal expansion coefficient that is highly compatible with the applied thermal barrier coating, higher strength, hardness and fracture toughness, phase stability at high temperatures, and good resistance to corrosion by environmental deposits (mainly composed of CaO, MgO, Al2O3 and SiO2, referred to as CMAS) are important parameters that affect their performance.

[0003] It should be noted that the above statements are only used to provide background technical information related to this application and do not necessarily constitute prior art. Summary of the Invention

[0004] In a first aspect of the present application, the present application proposes a coating material, the chemical formula of the coating material being MA1O3, wherein M includes at least one of Nd, Sm, Eu, Gd, Dy, Ho, Er, Yb, and Lu.

[0005] The coating material proposed in this application has excellent fracture toughness, low thermal conductivity, high thermal expansion coefficient and good resistance to environmental sediment corrosion.

[0006] In some embodiments, M includes at least two of Nd, Sm, Eu, Gd, Dy, Ho, Er, Yb, and Lu, and the molar ratio of any two M elements is (2-1):(1-2).

[0007] In some embodiments, the coating material has the chemical formula M1 x M2 y AlO3, wherein M1 includes at least one of Nd, Sm, and Eu, and M2 includes at least one of Gd, Dy, Er, Yb, and Lu, and x+y=1, 0.2≤x≤0.4. This allows for further modulation of the thermal expansion coefficient and thermal conductivity of the coating material through entropy engineering, while also improving the fracture toughness of the coating material.

[0008] In some embodiments, the coating material exhibits a pure phase at temperatures ranging from room temperature (25°C) to 1600°C. Thus, the coating material undergoes negligible phase change within the aforementioned extremely wide temperature range, thereby maintaining chemical and physical stability and maintaining its inherent properties, such as high strength, high fracture toughness, and high CMAS corrosion resistance.

[0009] In a second aspect, the present application provides a method for preparing a coating material, comprising: calcining a rare earth element oxide and aluminum oxide, wherein the rare earth element oxide includes at least one oxide corresponding to Nd, Sm, Eu, Gd, Dy, Ho, Er, Yb, and Lu; ball-milling the rare earth element oxide and aluminum oxide to obtain an oxide mixture; and subjecting the oxide mixture to a high-temperature phase-forming treatment to obtain the coating material. Thus, the coating material can be obtained using a relatively simple method.

[0010] The method proposed in this application allows for the synthesis of coating material powders of single-component or high-entropy rare earth aluminate compounds with a pure perovskite phase in a relatively simple and controllable process by mixing and calcining the reactant raw material powders. The product composition has a wide range of applications, a stable phase structure, and effectively protects coatings from CMAS corrosion. Furthermore, the powdered product is conveniently used for spraying environmental barrier coatings or hybrid thermal barrier coatings.

[0011] In some embodiments, the mass proportion of aluminum oxide in the oxide mixture is 20 wt%-24 wt%. As a result, the molar ratio of Al to rare earth elements in the coating material is approximately 1:1, which is conducive to forming a uniform and stable lattice structure when the material is formed.

[0012] In some embodiments, the temperature of the high-temperature phase forming treatment is 1300° C.-1500° C., and the time of the high-temperature phase forming treatment is 2 h-5 h.

[0013] In some embodiments, the calcination temperature is 900° C. to 1100° C., and the calcination time is 2 hours to 5 hours. The calcination temperature and time within the aforementioned ranges are beneficial for removing bound water and carbon oxides adsorbed by the rare earth element oxides due to contact with air, thereby purifying the reactant raw materials. This improves the quality of the resulting coating material.

[0014] In some embodiments, the rotation speed of the mixing ball milling process is 200 rpm-400 rpm, and the mixing ball milling process time is 2 hours-5 hours, thereby facilitating the thorough mixing of the rare earth element oxide and the aluminum oxide, thereby preparing a coating material with consistent composition.

[0015] In a third aspect of the present application, an environmental barrier coating is provided, comprising the coating material proposed in the present application, or a coating material prepared by the method proposed in the present application.

[0016] This application proposes an environmental barrier coating prepared from a coating material, which can achieve an isothermal thermal cycle life (1h cycle) of more than 1000 times at 1100°C for the environmental barrier coating, and has high stability and a long service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0018] Figure 1 The coating materials in the embodiment of the present application are rare earth aluminates NdAlO3, SmAlO3, EuAlO3, GdAlO3, DyAlO3, (Sm 1 / 3 Gd 1 / 3 Dy 1 / 3 )AlO3 is RAO-3, (Nd 1 / 5 Sm 1 / 5 Eu 1 / 5 Gd 1 / 5 Dy 1 / 5 ) XRD pattern of AlO3, i.e. RAO-5, fired ceramic block test;

[0019] Figure 2 This is an SEM image of the ferroelastic domain structure of the SmAlO3 sintered ceramic block in Example 1 of the present application;

[0020] Figure 3 For Example 2 of this application (Sm 1 / 3 Gd 1 / 3 Dy 1 / 3 ) SEM image of crack growth in AlO3 sintered ceramic block;

[0021] Figure 4 For Example 3 of this application (Nd 1 / 5 Sm 1 / 5 Eu 1 / 5 Gd 1 / 5 Dy 1 / 5 ) SEM image of AlO3 sintered ceramic block;

[0022] Figure 5 The thermal barrier coating material Gd2Zr2O7 (left figure, Figure a) and the embodiment 3 of the present application (Nd 1 / 5 Sm 1 / 5 Eu 1 / 5 Gd 1 / 5Dy 1 / 5) Comparison of cross-sectional SEM images of AlO3 sintered ceramic blocks after CMAS corrosion at 1300℃ for 20h. DETAILED DESCRIPTION

[0023] The following describes the embodiments of the present application in detail. Examples of the embodiments are shown in the accompanying drawings, but unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repeated descriptions of substantially identical structures may be omitted. This is to avoid unnecessary lengthiness in the following description and to facilitate understanding by those skilled in the art. In addition, the drawings and the following description are provided to enable those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0024] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as those commonly understood by technicians in the technical field to which this application belongs; the terms used in this application are only for the purpose of describing specific embodiments and are not intended to limit this application; unless otherwise specified, the numerical values ​​of the various parameters mentioned in this application can be measured using various measurement methods commonly used in the art (for example, they can be tested according to the methods given in the embodiments of this application).

[0025] The terms "include" and "have" in the description and claims of this application and any variations thereof are open expressions, that is, including the contents specified in this application but not excluding other contents.

[0026] In the description of this application, regardless of whether the word "about" or "approximately" is used, all numbers disclosed herein are approximate values. The value of each number may vary by less than 10% or by a reasonable difference considered by a person skilled in the art, such as 1%, 2%, 3%, 4% or 5%.

[0027] " range " disclosed in the present application is limited in the form of lower limit and upper limit, and given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of special range. The scope limited in this way can be to include end value or not include end value, and can be arbitrarily combined, that is, any lower limit can form a range with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for specific parameters, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range value 1 and 2 are listed, and if the maximum range value 3,4 and 5 are listed, then the following range can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this application, unless otherwise specified, the numerical range " ab " represents the abbreviation of any real number combination between a and b, wherein a and b are all real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0028] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0029] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0030] To further increase engine operating temperatures and boost thrust-to-weight ratios, ceramic-based composites (CMCs) are becoming the substrate material for aircraft engine and gas turbine blades due to their excellent oxidation resistance and high-temperature performance. In the engine's operating environment, CMCs still require surface treatments such as surface coatings to protect the internal fiber structure and mitigate damage from high-temperature molten salts, steam, and other materials. This coating structure is called a thermal barrier coating, and its coating material is a thermal barrier material.

[0031] In the relevant technology, thermal barrier materials are mainly based on materials such as pyrochlore structure silicates and mullite, including mainly yttrium partially stabilized zirconia (YSZ) and rare earth zirconate (Re2Zr2O7) coating materials. Among them, YSZ material has high strength and fracture toughness and low thermal conductivity, but above 1200°C, a phase change with volume change will occur, causing the coating to fail. Rare earth zirconates have low thermal conductivity and high-temperature phase stability, but low fracture toughness, which limits the service life of the coating material. At the same time, YSZ and rare earth zirconates have poor resistance to molten salt and steam corrosion, resulting in a short time for coating materials with them as the main component to provide effective protection in complex environments (such as gas turbine blades of ships in service at sea), and the protective effect as a thermal barrier coating alone is poor.

[0032] The coating material proposed in this application features a perovskite-structured aluminate (MAlO3), which exhibits excellent resistance to CMAS corrosion and water vapor, as well as high thermal expansion coefficient, hardness, and fracture toughness. The coating material proposed in this application can be applied as an environmental barrier coating or as a protective layer for thermal barrier coatings, further protecting the hot end of the blade.

[0033] In a first aspect of the present application, a coating material is proposed, the chemical formula of the coating material being MA1O3, wherein the M element includes at least one of Nd, Sm, Eu, Gd, Dy, Ho, Er, Yb, and Lu.

[0034] The coating material proposed in this application includes rare earth aluminates (abbreviated as RAP) with a deformed perovskite structure. The perovskite crystal structure of RAP has a microscopic ferroelastic domain configuration, which plays a strong role in energy absorption and crack deflection during crack propagation, and exhibits excellent fracture toughness. Figure 1 , except for NdAlO3 which has a rhombohedral perovskite structure, the other rare earth aluminates all have an orthorhombic perovskite structure, no second phase diffraction peaks, and high chemical purity. Therefore, among the coating materials that meet the MAlO3 requirement, except for NdAlO3 which has a pure rhombohedral phase, the other coating materials, including high entropy aluminates composed of 5 or more rare metal elements, are all single pure orthorhombic phases. The perovskite phase rare earth aluminates, including rhombohedral and orthorhombic phases, have good fracture toughness in sintered blocks due to the ferroelastic toughening effect, and the fracture toughness can reach or exceed 2.0MPa m 1 / 2 Among them, high entropy aluminates have high fracture toughness, which can exceed 3.0 MPa m due to the synergistic toughening effect of configurational entropy and ferroelastic domains. 1 / 2 Therefore, the coating material of the present application has excellent physical protection effect.

[0035] At the same time, the present application proposes that the coating material rare earth aluminate has a high thermal expansion coefficient, which is 9.5×10 -6K -1 -10.0×10 -6 K -1 , and the thermal expansion coefficients of rare earth zirconates and YSZ at this temperature are well matched. Furthermore, the rare earth aluminate coating material proposed in this application does not react with either zirconium oxide or zirconate, and can be used in conjunction with thermal barrier materials primarily composed of rare earth zirconates and / or YSZ, exhibiting good chemical compatibility and thermal expansion coefficient matching. The coating material proposed in this application can be used as an environmental barrier coating, combined with a thermal barrier coating composed of the aforementioned thermal barrier materials, to produce a protective layer having a composite layer structure.

[0036] Furthermore, the rare earth aluminate coating material proposed in this application reacts rapidly with CMAS to form a dense apatite and calcite reaction layer, which hinders further penetration of CMAS and increases its viscosity. This provides a high barrier against CMAS corrosion, resulting in strong resistance to CMAS corrosion and long-term protection.

[0037] In some embodiments, M includes at least two of Nd, Sm, Eu, Gd, Dy, Ho, Er, Yb, and Lu, and the molar ratio of any two M elements is (2-1):(1-2).

[0038] In some embodiments, the coating material has the chemical formula M1 x M2 y AlO3, wherein M1 comprises at least one of Nd, Sm, and Eu, and M2 comprises at least one of Gd, Dy, Er, Yb, and Lu, with x+y=1 and 0.2≤x≤0.4. The ratio of M1 to M2 in the coating material is within the aforementioned range. The mixing of light rare earth elements with heavy rare earth elements effectively stabilizes the perovskite phase structure of the rare earth aluminate. This allows for further modulation of the coating material's thermal expansion coefficient and thermal conductivity through entropy engineering, while also improving the coating material's fracture toughness.

[0039] In some embodiments, the coating material exhibits a pure phase at temperatures ranging from room temperature (25°C) to 1600°C. Thus, the coating material undergoes negligible phase change within the aforementioned extremely wide temperature range, thereby maintaining chemical and physical stability and maintaining its inherent properties, such as high strength, high fracture toughness, and high CMAS corrosion resistance.

[0040] In a second aspect of the present application, the present application proposes a method for preparing a coating material, comprising:

[0041] S1: calcining rare earth element oxides and alumina, wherein the rare earth element oxides include at least one of the corresponding oxides of Nd, Sm, Eu, Gd, Dy, Ho, Er, Yb, and Lu

[0042] Calcination treatment can reduce the material changes of rare earth element oxides and aluminum oxide caused by the interaction with moisture in the environment, so as to obtain high-purity corresponding metal oxides, thereby improving the purity and quality of the prepared coating material.

[0043] In some embodiments, the calcination temperature is 900°C to 1100°C, and the calcination time is 2 hours to 5 hours. The calcination temperature and time within the aforementioned ranges are beneficial for removing bound water and carbon oxides adsorbed in the rare earth element oxide due to contact with air, thereby purifying the reactant raw materials. This is beneficial for improving the quality of the prepared coating material. As an example, the calcination temperature can be 900°C, 950°C, 1000°C, 1050°C, or 1100°C.

[0044] S2: Mixing the rare earth element oxide and the aluminum oxide and subjecting them to ball milling to obtain an oxide mixture.

[0045] In some embodiments, the mass proportion of aluminum oxide in the oxide mixture is 20 wt%-24 wt%. As a result, the molar ratio of Al to rare earth elements in the coating material is approximately 1:1, which is conducive to forming a uniform and stable lattice structure when the material is formed.

[0046] In some embodiments, the rotation speed of the mixing ball milling process is 200 rpm-400 rpm, and the mixing ball milling process time is 2 hours-5 hours, thereby facilitating the thorough mixing of the rare earth element oxide and the aluminum oxide, thereby preparing a coating material with consistent composition.

[0047] As an example, the rotation speed of the mixing ball milling process can be 200 rpm, 250 rpm, 300 rpm, 350 rpm, or 400 rpm.

[0048] S3: subjecting the oxide mixture to a high-temperature phase-forming treatment to obtain the coating material

[0049] Through high-temperature phase formation treatment, Al and rare earth elements achieve lattice rearrangement, thereby obtaining the rare earth aluminate material structure in the coating material.

[0050] In some embodiments, the temperature of the high-temperature phase forming treatment is 1300°C-1500°C, and the time of the high-temperature phase forming treatment is 2h-5h. When the temperature and time of the high-temperature phase forming treatment are within the above range, alumina and rare earth element oxides can react to form orthorhombic or rhombohedral phase MAlO3 (rhombohedral phase NdAlO3). In the early stage of the reaction, a small amount of garnet phase M3Al5O may be formed due to local compositional inhomogeneity. 12Compared with the monoclinic phase M4Al2O9, as the reaction temperature heat is fully transferred and the reaction time increases, the reaction product gradually transforms into a pure perovskite phase. Specifically, for SmAlO3, a pure perovskite phase can be formed at 1300℃ for 5h. 1 / 5 Sm 1 / 5 Eu 1 / 5 Gd 1 / 5 Dy 1 / 5 )AlO3 requires a 5-hour heat preservation at 1450°C to form a pure perovskite phase. This helps reduce the internal impurities in the prepared coating material and increases the proportion of pure phases in the coating material, which is beneficial for the coating material to have high resistance to CMAS corrosion and other material properties as an environmental barrier coating material.

[0051] As an example, the temperature of the high temperature phase forming treatment may be 1300°C, 1350°C, 1400°C, 1450°C, or 1500°C.

[0052] In some embodiments, the method further includes: prior to the high-temperature phase forming treatment, the oxide mixture is sieved using a sieve mesh of 100-300 mesh. This increases the contact area between the rare earth element oxides and aluminum oxide in the oxide mixture, facilitates smooth reaction changes during the high-temperature phase forming treatment, and improves various properties of the prepared coating material.

[0053] In a third aspect of the present application, an environmental barrier coating is provided, comprising the coating material proposed in the present application, or a coating material prepared by the method proposed in the present application.

[0054] This application proposes an environmental barrier coating fabricated from a coating material that can achieve an isothermal thermal cycle life (1-hour cycle) of over 1000 cycles at 1100°C, demonstrating high stability and a long service life. Furthermore, the rare earth aluminate coating material employed in this application exhibits excellent chemical compatibility with both YSZ and rare earth zirconate, allowing it to be used in conjunction with these materials to form a double-layer coating, expanding the application areas and scope of the coating material.

[0055] In some embodiments, the environmental barrier coating is prepared by atmospheric plasma spraying.

[0056] In some embodiments, the environmental barrier coating can be used in high-temperature hot-end components of aircraft engines or gas turbines. Thus, the environmental barrier coating can meet the operating temperature range of 1300°C-1600°C for high-temperature hot-end components and provide effective protection against steam loads and CMAS loads in the operating environment of high-temperature hot-end components.

[0057] In some embodiments, it includes a nickel-based high-temperature alloy substrate, a metal bonding layer is provided on the surface of the nickel-based high-temperature alloy substrate; a thermal barrier coating is provided on the surface of the metal bonding layer; an environmental barrier coating is provided on the surface of the thermal barrier coating; the thermal barrier coating includes at least one of a YSZ coating or a rare earth zirconate coating; the material used for the environmental barrier coating is the coating material proposed in this application, forming a composite double-layer coating.

[0058] The present invention will be described below by way of specific examples. It should be noted that the following examples are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. Where specific techniques or conditions are not specified in the examples, they are determined according to the techniques or conditions described in the literature in this area or according to the product specifications. Reagents or instruments not specified by manufacturer are all commercially available conventional products.

[0059] Example 1

[0060] Synthesis of SmAlO3:

[0061] Sm2O3 (purity 99.99%) and Al2O3 (purity 99.99%) were calcined at 1000°C for 5 h.

[0062] The two powders were weighed according to the stoichiometric ratio and loaded into a ball mill. Zirconia balls were placed in the ball mill. After adding anhydrous ethanol, the mixture was ball milled for 3 h at a rotation speed of 300 r / min for mixed ball milling.

[0063] After the ball milling is completed, the slurry in the ball mill is transferred to a rotary evaporator and evaporated to dryness at 45°C using a vacuum rotary evaporation method. The powder is then dried in an oven at 100°C for 12 hours, then ground and crushed to pass through a 200-mesh sieve. The sieved powder is subjected to high-temperature phase treatment in a high-temperature muffle furnace. After being kept at 1300°C for 5 hours, it is cooled to room temperature with the furnace. The powder is mechanically ground and fully crushed and then ball milled again at a speed of 300r / min for 5 hours. After the ball milling is completed, it is rotary evaporated and dried, ground and crushed to pass through a 200-mesh sieve to obtain SmAlO3 powder. The obtained powder is dry pressed at 50MPa for 5 minutes in a metal mold, cold isostatically pressed at 300MPa for 1 minute, sintered in a high-temperature muffle furnace, and kept at 1600°C for 2 hours to obtain a dense SmAlO3 ceramic block with a density of >99% for subsequent testing. The resulting blocks were polished using 30 μm, 15 μm, 9 μm, 6 μm, 3 μm, and 1 μm diamond sandpaper, respectively, and then hot-etched in a high-temperature muffle furnace at 1550°C for 30 min. The resulting blocks were used for SEM testing.

[0064] Example 2

[0065] Synthesis (Sm 1 / 3 Gd 1 / 3 Dy1 / 3 )AlO3:

[0066] Sm2O3 (purity 99.99%), Gd2O3 (purity 99.99%), Dy2O3 (purity 99.99%), and Al2O3 (purity 99.99%) were calcined at 1000°C for 5 h.

[0067] The four powders were weighed according to the stoichiometric ratio and loaded into a ball mill. Zirconia balls were placed in the ball mill. After adding anhydrous ethanol, the mixture was ball milled for 3 h at a rotation speed of 300 r / min for mixed ball milling.

[0068] After the ball milling is completed, the slurry in the ball mill is transferred to a rotary evaporator, and the powder is evaporated to dryness at 45 ° C using a vacuum rotary evaporator. The powder is then dried in an oven at 100 ° C for 12 h, and then the powder is ground and crushed to pass through a 200-mesh sieve. The sieved powder is subjected to high-temperature phase treatment in a high-temperature muffle furnace, kept at 1450 ° C for 5 h, and then cooled to room temperature with the furnace. The powder is mechanically ground and fully crushed and then ball milled again at a speed of 300 r / min for 5 h. After the ball milling is completed, it is rotary evaporated and dried, and ground and crushed to pass through a 200-mesh sieve to obtain (Sm 1 / 3Gd 1 / 3 Dy 1 / 3 )AlO3 powder. The obtained powder was dry pressed in a metal mold at 50MPa for 10 minutes, cold isostatically pressed at 300MPa for 1 minute, sintered in a high-temperature muffle furnace, and kept at 1600℃ for 10 hours to obtain a dense (Sm 1 / 3 Gd 1 / 3Dy 1 / 3 ) AlO3 ceramic blocks were used for subsequent testing. The resulting blocks were polished using 30μm, 15μm, 9μm, 6μm, 3μm, and 1μm diamond sandpaper in that order, and then thermally etched in a high-temperature muffle furnace at 1550°C for 30 minutes. The resulting blocks were then used for SEM testing.

[0069] Example 3

[0070] Synthesis of high entropy aluminates (Nd 1 / 5 Sm 1 / 5 Eu 1 / 5 Gd 1 / 5 Dy 1 / 5 )AlO3:

[0071] Nd2O3 (purity 99.99%), Sm2O3 (purity 99.99%), Eu2O3 (purity 99.99%), Gd2O3 (purity 99.99%), Dy2O3 (purity 99.99%), and Al2O3 (purity 99.99%) were calcined at 1000°C for 5 hours.

[0072] Six kinds of powders were weighed according to the stoichiometric ratio and loaded into a ball mill. Zirconia balls were placed in the ball mill. After adding anhydrous ethanol, the mixture was ball milled for 5 hours at a rotation speed of 300 r / min for mixed ball milling.

[0073] After the ball milling is completed, the slurry in the ball mill is transferred to a rotary evaporator, and the powder is evaporated to dryness at 45 ° C using a vacuum rotary evaporator. The powder is then dried in an oven at 100 ° C for 12 h, and then the powder is ground and crushed to pass through a 200-mesh sieve. The sieved powder is subjected to high-temperature phase treatment in a high-temperature muffle furnace, kept at 1450 ° C for 5 h, and then cooled to room temperature with the furnace. The powder is mechanically ground and fully crushed and then ball milled again at a speed of 300 r / min for 20 h. After the end, it is rotary evaporated and dried, and ground and crushed to pass through a 200-mesh sieve to obtain high entropy (Nd 1 / 5 Sm 1 / 5 Eu 1 / 5 Gd 1 / 5 Dy 1 / 5 )AlO3 powder. The obtained powder was dry pressed in a metal mold at 50MPa for 10 minutes, cold isostatically pressed at 300MPa for 1 minute, sintered in a high-temperature muffle furnace, and kept at 1600℃ for 10 hours to obtain a dense (Nd 1 / 5 Sm 1 / 5 Eu 1 / 5 Gd 1 / 5 Dy 1 / 5 ) AlO3 ceramic blocks were used for subsequent testing. The resulting blocks were polished using 30μm, 15μm, 9μm, 6μm, 3μm, and 1μm diamond sandpaper in that order, and then thermally etched in a high-temperature muffle furnace at 1550°C for 30 minutes. The resulting blocks were then used for SEM testing.

[0074] Example 4

[0075] Synthesis of high entropy aluminates (Nd 1 / 7 Sm 1 / 7 Eu 1 / 7 Gd 1 / 7 Dy 1 / 7 Ho 1 / 7 Er 1 / 7 )AlO3:

[0076] Nd2O3 (purity 99.99%), Sm2O3 (purity 99.99%), Eu2O3 (purity 99.99%), Gd2O3 (purity 99.99%), Dy2O3 (purity 99.99%), Ho2O3 (purity 99.99%), Er2O3 (purity 99.99%), and Al2O3 (purity 99.99%) were calcined at 1000°C for 5 hours.

[0077] Eight kinds of powders were weighed according to the stoichiometric ratio and loaded into a ball mill jar. Zirconia ball milling balls were loaded into the ball mill jar. After adding anhydrous ethanol, the powders were ball milled for 5 hours at a rotation speed of 300 r / min for mixed ball milling treatment.

[0078] After the ball milling is completed, the slurry in the ball mill is transferred to a rotary evaporator, and the powder is evaporated to dryness at 45 ° C using a vacuum rotary evaporator. The powder is then dried in an oven at 100 ° C for 12 h, and then the powder is ground and crushed to pass through a 200-mesh sieve. The sieved powder is subjected to high-temperature phase treatment in a high-temperature muffle furnace, kept at 1400 ° C for 5 h, and then cooled to room temperature with the furnace. The powder is mechanically ground and fully crushed and then ball milled again at a speed of 300 r / min for 24 h. After the end, it is rotary evaporated and dried, and ground and crushed to pass through a 200-mesh sieve to obtain high entropy (Nd 1 / 7 Sm 1 / 7 Eu 1 / 7 Gd 1 / 7 Dy 1 / 7 Ho 1 / 7 Er 1 / 7 )AlO3 powder.

[0079] Example 5

[0080] Synthesis of high entropy aluminates (Nd 1 / 11 Sm 1 / 11 Eu 1 / 11 Gd 2 / 11 Dy 2 / 11 Ho 2 / 11 Er 2 / 11 )AlO3:

[0081] Nd2O3 (purity 99.99%), Sm2O3 (purity 99.99%), Eu2O3 (purity 99.99%), Gd2O3 (purity 99.99%), Dy2O3 (purity 99.99%), Ho2O3 (purity 99.99%), Er2O3 (purity 99.99%), and Al2O3 (purity 99.99%) were calcined at 1000°C for 5 hours.

[0082] Eight kinds of powders were weighed according to the stoichiometric ratio and loaded into a ball mill jar. Zirconia ball milling balls were loaded into the ball mill jar. After adding anhydrous ethanol, the powders were ball milled for 5 hours at a rotation speed of 300 r / min for mixed ball milling treatment.

[0083] After the ball milling is completed, the slurry in the ball mill is transferred to a rotary evaporator, and the vacuum rotary evaporation method is used to evaporate to dryness at 45 ° C. The powder is then dried in an oven at 100 ° C for 12 hours, and then the powder is ground and crushed to pass through a 200 mesh sieve. The sieved powder is subjected to high-temperature phase treatment in a high-temperature muffle furnace, kept at 1400 ° C for 5 hours, and then cooled to room temperature with the furnace. The powder is mechanically ground and fully crushed and then ball milled again at a speed of 300r / min for 24 hours. After the end, it is rotary evaporated and dried, and ground and crushed to pass through a 200 mesh sieve to obtain high entropy (Nd 1 / 7 Sm 1 / 7 Eu 1 / 7 Gd 1 / 7 Dy 1 / 7 Ho 1 / 7 Er 1 / 7 )AlO3 powder.

[0084] Test method:

[0085] 1. Crack extension test

[0086] The powder was dry pressed into shape and then cold isostatically pressed at 300 MPa for 1 min. It was then sintered in a high-temperature muffle furnace at 1600°C for 10 h to obtain a fired ceramic block for testing.

[0087] 2. CMAS corrosion resistance test

[0088] The ceramic blocks sintered at 1600℃ for 10h were polished with 30μm, 15μm, 9μm, 6μm, 3μm and 1μm diamond sandpaper respectively, and then covered with 30mg / cm 2 CMAS powder. The CMAS powder used is CaO (99.99% purity), MgO (99.99% purity), Al2O3 (99.99% purity), and SiO2 (99.99% purity) in a mass ratio of 33wt%:9wt%:13wt%:45wt%, and is obtained by ball milling. After coating the rare earth aluminate block with CMAS powder, the block is kept in a high-temperature muffle furnace at 1300°C for 5-100 hours. After removal, the sample is cut with a diamond wire cutter, and cross-sections are taken. After polishing with 30μm, 15μm, 9μm, 6μm, 3μm, and 1μm diamond sandpaper, the corrosion condition is observed under a scanning electron microscope.

[0089] 3. Thermal conductivity test

[0090] The resulting ceramic blocks were polished using 30μm, 15μm, 9μm, 6μm, 3μm, and 1μm diamond sandpaper, respectively, and then thermally etched in a high-temperature muffle furnace at 1550°C for 30 minutes. The thermally etched ceramic blocks were then processed into discs with a diameter of 10mm and a thickness of 1mm, and their thermal conductivity was tested using a laser flash thermal conductivity tester.

[0091] 4. Thermal expansion coefficient test

[0092] The ceramic block was processed into a strip sample with a size of 20 mm × 4 mm × 3 mm, and its thermal expansion coefficient was tested using a thermomechanical analyzer (TMA).

[0093] 5. Fracture toughness test

[0094] The ceramic block was processed into a strip sample of 20mm×4mm×2mm. A 2mm deep incision was made in the middle of the strip sample at 4mm direction using a 0.25mm diamond wire cutting machine. The fracture toughness was tested using the single-edge notch beam method.

[0095] Test results: See Table 1.

[0096] Table 1

[0097] <![CDATA[Thermal conductivity (W / m -1 K -1 )]]> <![CDATA[Coefficient of thermal expansion (×10 -6 K -1 )]]> <![CDATA[Fracture toughness (MPa m 1 / 2 )]]> Example 1 3.7 9.7 2.1 Example 2 2.58 9.5 2.6 Example 3 2.64 9.6 3.4

[0098] As can be seen from Table 1, the coating material proposed in this application has low thermal conductivity, high thermal expansion coefficient and excellent fracture toughness.

[0099] Depend on Figure 2 It can be seen that in the SEM image of the ferroelastic domain structure of the SmAlO3 sintered ceramic block in Example 1, a distinctive ferroelastic domain structure is formed, which helps the coating material absorb crack propagation energy, deflect the crack, and significantly improve the fracture toughness.

[0100] Depend on Figure 3 It can be seen that in Example 2 (Sm 1 / 3 Gd 1 / 3 Dy 1 / 3 ) The crack propagation SEM image of the AlO3 sintered ceramic block shows that the crack is significantly deflected and almost completely propagates along the grain boundary, showing a strong resistance to crack propagation inside the grain. Therefore, the coating material has a high fracture toughness.

[0101] Depend on Figure 4 It can be seen that in Example 3 (Nd 1 / 5 Sm 1 / 5 Eu 1 / 5 Gd 1 / 5 Dy 1 / 5)In the crack propagation SEM image of the AlO3 sintered ceramic block, not only did the cracks almost completely propagate along the grain boundaries, but bifurcation and bridging of cracks were also observed in the middle, showing stronger fracture toughness. Therefore, the coating material has higher fracture toughness.

[0102] Depend on Figure 5 It can be seen that in Example 3 (Nd 1 / 5 Sm 1 / 5 Eu 1 / 5 Gd 1 / 5 Dy 1 / 5 ) The test of CMAS corrosion resistance test of AlO3 ceramic sintered blocks (right figure, figure b) shows that under the conditions of 1300℃ and 5h, the thickness of CMAS corrosion layer is ≤40μm, compared with the corrosion layer thickness of thermal barrier coating material Gd2Zr2O7 (left figure, figure a) exceeding 100μm, showing good resistance to CMAS corrosion.

[0103] The above test results show that the coating material proposed in this application has excellent fracture toughness, low thermal conductivity, high thermal expansion coefficient and good resistance to CMAS corrosion.

[0104] In the description of this application, "A and / or B" may include the case of A alone, the case of B alone, or any of the cases of A and B, where A and B are only used for example, and may be any technical feature connected by "and / or" in this application.

[0105] In this application, the writing order of each step does not mean a strict execution order and does not constitute any limitation on the implementation process. The specific execution order of each step should be determined by its function and possible internal logic. Unless otherwise specified, all steps of this application can be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or steps (b) and (a) performed sequentially. For example, it is mentioned that the method may also include step (c), indicating that step (c) can be added to the method in any order. For example, the method may include steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0106] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and any embodiments having substantially the same structure and effect as the technical concept within the scope of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the present application, any other embodiments that can be conceived by those skilled in the art and that combine some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A coating material, characterized in that: The chemical formula of the coating material is MA1O3, wherein M includes at least one of Nd, Sm, Eu, Gd, Dy, Ho, Er, Yb, and Lu.

2. The coating material according to claim 1, characterized in that M includes at least two of Nd, Sm, Eu, Gd, Dy, Ho, Er, Yb, and Lu, and the molar ratio of any two M elements is (2-1):(1-2).

3. The coating material according to claim 2, characterized in that The chemical formula of the coating material is M1 x M2 y AlO3, wherein the M1 includes at least one of Nd, Sm, and Eu, the M2 includes at least one of Gd, Dy, Er, Yb, and Lu, x+y=1, 0.2≤x≤0.

4.

4. The coating material according to any one of claims 1 to 3, characterized in that From room temperature (25°C) to 1600°C, it appears as a pure phase.

5. A method for preparing the coating material according to any one of claims 1 to 4, characterized in that: include: calcining a rare earth element oxide and alumina, wherein the rare earth element oxide comprises at least one of the corresponding oxides of Nd, Sm, Eu, Gd, Dy, Ho, Er, Yb, and Lu; Mixing the rare earth element oxide and the aluminum oxide and subjecting them to ball milling to obtain an oxide mixture; The oxide mixture is subjected to high-temperature phase-forming treatment to obtain the coating material.

6. The method according to claim 5, characterized in that In the oxide mixture, the mass proportion of the aluminum oxide is 20 wt%-24 wt%.

7. The method according to claim 5, characterized in that The temperature of the high-temperature phase forming treatment is 1300° C.-1500° C., and the time of the high-temperature phase forming treatment is 2 h-5 h.

8. The method according to claim 5, characterized in that The calcination temperature is 900° C.-1100° C., and the calcination time is 2 h-5 h.

9. The method according to claim 5, characterized in that The rotation speed of the mixing ball milling process is 200 rpm-400 rpm, and the time of the mixing ball milling process is 2 h-5 h.

10. An environmental barrier coating, characterized in that: The environmental barrier coating comprises the coating material according to any one of claims 1 to 4, or the coating material prepared by the method according to any one of claims 5 to 9.

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