阅读说明：本技术 一种在基体材料上形成的梯度环境障涂层及其制备方法 (Gradient environmental barrier coating formed on base material and preparation method thereof ) 是由 张宝鹏 裴雨辰 于新民 刘伟 霍鹏飞 于 2020-07-07 设计创作，主要内容包括：本发明涉及一种在基体材料上形成的梯度环境障涂层及其制备方法。梯度环境障涂层自基体材料向外依次包括硅粘结层、莫来石层和Lu<Sub>2</Sub>SiO<Sub>5</Sub>-Er<Sub>2</Sub>SiO<Sub>5</Sub>梯度陶瓷层；Lu<Sub>2</Sub>SiO<Sub>5</Sub>-Er<Sub>2</Sub>SiO<Sub>5</Sub>梯度陶瓷层包括由不同摩尔比的硅酸镥和硅酸铒混合而成的Lu<Sub>2</Sub>SiO<Sub>5</Sub>-Er<Sub>2</Sub>SiO<Sub>5</Sub>内层和Lu<Sub>2</Sub>SiO<Sub>5</Sub>-Er<Sub>2</Sub>SiO<Sub>5</Sub>外层。所述方法为：通过低压等离子喷涂法在基体材料的表面依次制备硅粘结层、莫来石层、Lu<Sub>2</Sub>SiO<Sub>5</Sub>-Er<Sub>2</Sub>SiO<Sub>5</Sub>内层和Lu<Sub>2</Sub>SiO<Sub>5</Sub>-Er<Sub>2</Sub>SiO<Sub>5</Sub>外层,制得梯度环境障涂层。本发明的梯度环境障涂层抗热冲击性能优异,在高温抗水-氧腐蚀环境下材料的失重率低。(The invention relates to a gradient environmental barrier coating formed on a base material and a preparation method thereof. The gradient environmental barrier coating comprises a silicon bonding layer, a mullite layer and Lu from a base material to the outside in sequence 2 SiO 5 ‑Er 2 SiO 5 A gradient ceramic layer; lu (Lu) 2 SiO 5 ‑Er 2 SiO 5 The gradient ceramic layer comprises Lu mixed by lutetium silicate and erbium silicate with different molar ratios 2 SiO 5 ‑Er 2 SiO 5 Inner layer and Lu 2 SiO 5 ‑Er 2 SiO 5 And (4) an outer layer. The method comprises the following steps: sequentially preparing a silicon bonding layer, a mullite layer and Lu on the surface of a base material by a low-pressure plasma spraying method 2 SiO 5 ‑Er 2 SiO 5 Inner layer and Lu 2 SiO 5 ‑Er 2 SiO 5 And preparing a gradient environmental barrier coating. The gradient environment barrier coating has excellent thermal shock resistance, and the weight loss rate of the material is low in a high-temperature water-oxygen corrosion resistant environment.)

1. A gradient environmental barrier coating formed on a substrate material, characterized by:

the gradient environmental barrier coating sequentially comprises a silicon bonding layer, a mullite layer and Lu from a base material to the outside₂SiO₅-Er₂SiO₅A gradient ceramic layer;

The Lu₂SiO₅-Er₂SiO₅The gradient ceramic layer comprises Lu mixed by lutetium silicate and erbium silicate with different molar ratios₂SiO₅-Er₂SiO₅Inner layer and Lu₂SiO₅-Er₂SiO₅And (4) an outer layer.

2. The gradient environmental barrier coating of claim 1, wherein:

in the Lu₂SiO₅-Er₂SiO₅In the inner layer, the molar ratio of the lutetium silicate to the erbium silicate is (0.8-1.2): 1; and/or

In the Lu₂SiO₅-Er₂SiO₅In the outer layer, the molar ratio of the lutetium silicate to the erbium silicate is (3.5-4.5): 1.

3. A gradient environmental barrier coating according to claim 1 or 2, wherein:

the thickness of the silicon bonding layer is 60-100 mu m;

the thickness of the mullite layer is 60-100 mu m; and/or

The Lu₂SiO₅-Er₂SiO₅The thickness of the gradient ceramic layer is 150-200 μm.

4. A method of producing a gradient environmental barrier coating according to any one of claims 1 to 3, comprising the steps of:

(1) mixing silicon powder, mullite powder and Lu (Lu) formed by mixing lutetium silicate powder and erbium silicate powder in different molar ratios₂SiO₅-Er₂SiO₅Inner layer mixed powder A and Lu₂SiO₅-Er₂SiO₅Respectively loading the outer layer mixed powder B into a powder feeder of low-pressure plasma spraying equipment and drying;

(2) fixing the base material on a rotating table in a spraying cabin of low-pressure plasma spraying equipment; and

(3) Sequentially preparing the silicon bonding layer, the mullite layer and the Lu on the surface of a base material by a low-pressure plasma spraying method₂SiO₅-Er₂SiO₅Inner layer and the Lu₂SiO₅-Er₂SiO₅An outer layer, whereby the gradient environmental barrier coating is produced on the surface of a base material.

5. The method of claim 4, wherein:

the drying temperature is 65-75 ℃, and the drying time is 3-5 h;

in the process of preparing the gradient environment barrier coating, the surface of the base material is heated by adopting a plasma jet heating mode to be 700-800 ℃; and/or

Preparing the Lu by low pressure plasma spraying under high power conditions₂SiO₅-Er₂SiO₅Inner layer and the Lu₂SiO₅-Er₂SiO₅Outer layer, preferably, the Lu is prepared₂SiO₅-Er₂SiO₅Inner layer and the Lu₂SiO₅-Er₂SiO₅The outer spraying power is 75-80 kW.

6. The production method according to claim 4 or 5, characterized in that:

in the process of preparing the silicon bonding layer, argon and helium are used as plasma gases, the flow rate of the argon is 20-50L/min, the flow rate of the helium is 2-15L/min, the spraying distance is 200-500 mm, the rotating speed of a rotating table is 3-10 r/min, the arc voltage of low-pressure plasma spraying equipment is 10-20V, the arc current is 400-700A, and the powder feeding rate of silicon powder is 10-20 g/min.

7. The production method according to claim 4 or 5, characterized in that:

in the process of preparing the mullite layer, argon and helium are used as plasma gases, the flow of the argon is 20-50L/min, the flow of the helium is 10-20L/min, the spraying distance is 400-700 mm, the rotating speed of a rotating table is 3-10 r/min, the arc voltage of low-pressure plasma spraying equipment is 20-40V, the arc current is 1000-1300A, and the powder feeding rate of mullite powder is 20-30 g/min.

8. The production method according to claim 4 or 5, characterized in that:

in the preparation of the Lu₂SiO₅-Er₂SiO₅Inner layer and/or the Lu₂SiO₅-Er₂SiO₅In the outer layer process, argon and helium are used as plasma gases, the flow rate of the argon is 20-50L/min, the flow rate of the helium is 30-60L/min, the spraying distance is 400-700 mm, the rotating speed of a rotating table is 5-15 r/min, the arc voltage of low-pressure plasma spraying equipment is 35-40V, the arc current is 2000-2200A, the spraying power is 75-80 kW, and Lu₂SiO₅-Er₂SiO₅Inner layer mixed powder A and/or Lu₂SiO₅-Er₂SiO₅The powder feeding rate of the outer layer mixed powder B is 30-40 g/min.

9. The production method according to claim 4 or 5, characterized in that:

the particle size of the silicon powder is 3-10 mu m;

the particle size of the mullite powder is 5-30 mu m; and/or

Lu₂SiO₅-Er₂SiO₅Inner layer mixed powder A and/or Lu₂SiO₅-Er₂SiO₅The particle size of the outer layer mixed powder B is 10-40 μm.

10. A composite comprising the gradient environmental barrier coating of any one of claims 1 to 3 or the gradient environmental barrier coating produced by the method of any one of claims 4 to 9.

Technical Field

The invention belongs to the technical field of thermal protection coating materials, and particularly relates to a gradient environmental barrier coating formed on a base material and a preparation method thereof.

Background

Compared with high-temperature alloy, the matrix material such as the ceramic matrix composite has higher high-temperature stability and lower density, can improve the temperature of the front opening of the turbine, can reduce the structural weight, reduce the oil consumption and improve the working efficiency of the engine, and is one of important candidate materials of a high-performance aeroengine thermostructure component. Under the high-temperature dry environment, the ceramic matrix composite (such as C/SiC, SiC/SiC and the like) can form dense SiO on the surface after being oxidized ₂The oxide film inhibits the diffusion of the oxidizing atmosphere into the interior, so that the oxide film has good high-temperature oxidation resistance. However, in the working environment of the engine, high-temperature water vapor and molten salt can react with SiO₂The dense protective layer reacts to form volatile Si (OH)₄Leading to rapid degradation and failure of the composite. Therefore, the use requirements of a new-generation high-performance engine cannot be met only by the ceramic matrix composite substrate, and a high-temperature-resistant environment barrier coating needs to be coated on the surface of the composite material for protection, so that the performances of high temperature, water vapor corrosion resistance and the like of the composite material are improved, and the service life of a thermal structural component of the composite material is further prolonged.

The rare earth silicate system coating is an environment barrier coating with the most application prospect at present, and the rare earth silicate material in the coating is positioned on the outermost layer of the coating. The rare earth silicate material has lower thermal expansion coefficient and lower SiO₂The product has high activity and high phase structure stability in high-temperature water-oxygen environment. However, in an aeroengine environment, SiO₂Still has certain volatility, may lead to the coating in the use defect, reduces the life of environmental barrier coating. For example, current ceramic matrix composites are based on ytterbium (Yb) silicate in single or multiple layers ₂SiO₅) When the layer is used as an environmental barrier coating, the thermal shock resistance and the high-temperature water-oxygen corrosion resistance of the environmental barrier coating are both required to be improved. Chinese patent application CN102249735A discloses a method for preparing environmental barrier coating at low temperature, which discloses mixing scandium silicate (Sc) with polyazetasilane as precursor₂Si₂O₇) Preparation of powderSlurry using Li₂CO₃Preparation of Sc as sintering aid at 1250 deg.C₂Si₂O₇The thermal shock resistance and the high temperature water-oxygen corrosion resistance of the environmental barrier coating are also to be further improved.

At present, the preparation technology of the environmental barrier coating is various, and the preparation technology mainly comprises atmospheric plasma spraying, electron beam physical vapor deposition, chemical vapor deposition and the like. However, for the multi-layer complex system of environmental barrier coatings, the above preparation methods all have certain limitations, including low deposition efficiency, high cost, etc. Compared with the preparation method, the low-pressure high-power plasma spraying technology can carry out high-power spraying in a low-pressure inert gas environment, has high jet temperature and high speed, has the advantages of high deposition efficiency, low cost, uniform coating and the like, and is expected to realize the rapid and integrated preparation of the multilayer environment barrier coating.

In view of the above, it is very desirable to provide an environmental barrier coating with excellent thermal shock resistance and excellent high temperature water-oxygen corrosion resistance and a preparation method thereof.

Disclosure of Invention

In order to solve the technical problems in the prior art, the invention provides a gradient environmental barrier coating formed on a base material and a preparation method thereof. The gradient environment barrier coating has excellent thermal shock resistance, and the weight loss rate of the material is low in a high-temperature water-oxygen corrosion environment.

To achieve the above object, the present invention provides in a first aspect a gradient environmental barrier coating formed on a base material, the gradient environmental barrier coating comprising, in order from the base material, a bonding layer of silicon, a layer of mullite and Lu₂SiO₅-Er₂SiO₅A gradient ceramic layer; the Lu₂SiO₅-Er₂SiO₅The gradient ceramic layer comprises lutetium silicate and erbium silicate mixed in different molar ratiosLu₂SiO₅-Er₂SiO₅Inner layer and Lu₂SiO₅-Er₂SiO₅And (4) an outer layer.

Preferably, in the Lu₂SiO₅-Er₂SiO₅In the inner layer, the molar ratio of the lutetium silicate to the erbium silicate is (0.8-1.2): 1; and/or in the Lu ₂SiO₅-Er₂SiO₅In the outer layer, the molar ratio of the lutetium silicate to the erbium silicate is (3.5-4.5): 1.

Preferably, the thickness of the silicon bonding layer is 60-100 μm; the thickness of the mullite layer is 60-100 mu m; and/or the Lu₂SiO₅-Er₂SiO₅The thickness of the gradient ceramic layer is 150-200 μm.

The present invention provides in a second aspect a method of preparing a gradient environmental barrier coating according to the present invention as defined in the first aspect, the method comprising the steps of:

(1) mixing silicon powder, mullite powder and Lu (Lu) formed by mixing lutetium silicate powder and erbium silicate powder in different molar ratios₂SiO₅-Er₂SiO₅Inner layer mixed powder A and Lu₂SiO₅-Er₂SiO₅Respectively loading the outer layer mixed powder B into a powder feeder of low-pressure plasma spraying equipment and drying;

(2) fixing the base material on a rotating table in a spraying cabin of low-pressure plasma spraying equipment; and

(3) sequentially preparing the silicon bonding layer, the mullite layer and the Lu on the surface of a base material by a low-pressure plasma spraying method₂SiO₅-Er₂SiO₅Inner layer and the Lu₂SiO₅-Er₂SiO₅An outer layer, whereby the gradient environmental barrier coating is produced on the surface of a base material.

Preferably, the temperature of the drying treatment is 65-75 ℃, and the time of the drying treatment is 3-5 h; in the process of preparing the gradient environment barrier coating, the surface of the base material is heated by adopting a plasma jet heating mode to be 700-800 ℃; and/or at height Preparing the Lu by a low pressure plasma spraying method under the power condition₂SiO₅-Er₂SiO₅Inner layer and the Lu₂SiO₅-Er₂SiO₅Outer layer, preferably, the Lu is prepared₂SiO₅-Er₂SiO₅Inner layer and the Lu₂SiO₅-Er₂SiO₅The outer spraying power is 75-80 kW.

Preferably, in the process of preparing the silicon bonding layer, argon and helium are used as plasma gases, the flow rate of the argon is 20-50L/min, the flow rate of the helium is 2-15L/min, the spraying distance is 200-500 mm, the rotating speed of a rotating table is 3-10 r/min, the arc voltage of low-pressure plasma spraying equipment is 10-20V, the arc current is 400-700A, and the powder feeding rate of silicon powder is 10-20 g/min.

Preferably, in the process of preparing the mullite layer, argon and helium are used as plasma gases, the flow of the argon is 20-50L/min, the flow of the helium is 10-20L/min, the spraying distance is 400-700 mm, the rotating speed of a rotating table is 3-10 r/min, the arc voltage of low-pressure plasma spraying equipment is 20-40V, the arc current is 1000-1300A, and the powder feeding rate of mullite powder is 20-30 g/min.

Preferably, in the preparation of the Lu₂SiO₅-Er₂SiO₅Inner layer and/or the Lu₂SiO₅-Er₂SiO₅In the outer layer process, argon and helium are used as plasma gases, the flow rate of the argon is 20-50L/min, the flow rate of the helium is 30-60L/min, the spraying distance is 400-700 mm, the rotating speed of a rotating table is 5-15 r/min, the arc voltage of low-pressure plasma spraying equipment is 35-40V, the arc current is 2000-2200A, the spraying power is 75-80 kW, and Lu ₂SiO₅-Er₂SiO₅Inner layer mixed powder A and/or Lu₂SiO₅-Er₂SiO₅The powder feeding rate of the outer layer mixed powder B is 30-40 g/min.

Preferably, the particle size of the silicon powder is 3-10 μm; the particle size of the mullite powder is 5-30 mu m; and/or Lu₂SiO₅-Er₂SiO₅Inner layer mixed powder A and/or Lu₂SiO₅-Er₂SiO₅The particle size of the outer layer mixed powder B is 10-40 μm.

In a third aspect, the present invention provides a composite material comprising a gradient environmental barrier coating according to the first aspect of the present invention or a gradient environmental barrier coating produced according to the method of manufacture according to the second aspect of the present invention.

Compared with the prior art, the invention at least has the following beneficial effects:

(1) the gradient environmental barrier coating comprises a silicon bonding layer, a mullite layer (mullite component transition layer) and Lu from a base material to the outside in sequence₂SiO₅-Er₂SiO₅Gradient ceramic layer, rare earth silicate gradient ceramic coating (Lu)₂SiO₅-Er₂SiO₅Gradient ceramic layer) is mainly used for preventing water vapor from contacting with a base material (such as a ceramic matrix composite), improving the high-temperature water-oxygen corrosion resistance of the material and prolonging the high-temperature service life; in addition, the use of a mullite composition transition layer and a Si bond layer work together to alleviate the problem of mismatch in thermal expansion coefficients between the rare earth silicate gradient coating and the base material (substrate).

(2) The Lu in the present invention₂SiO₅-Er₂SiO₅The gradient ceramic layer comprises Lu mixed by lutetium silicate and erbium silicate with different molar ratios₂SiO₅-Er₂SiO₅Inner layer and Lu₂SiO₅-Er₂SiO₅Outer layer, Lu₂SiO₅-Er₂SiO₅Inner layer and Lu₂SiO₅-Er₂SiO₅The material of the outer layer is lutetium silicate (Lu)₂SiO₅) With erbium silicate (Er)₂SiO₅) In some preferred embodiments, in the Lu₂SiO₅-Er₂SiO₅In the inner layer, the molar ratio of the lutetium silicate to the erbium silicate is (0.8-1.2): 1, and Lu is₂SiO₅-Er₂SiO₅In the outer layer, the molar ratio of the lutetium silicate to the erbium silicate is (3.5-4.5): 1, and the lutetium silicate to the erbium silicate are diluted with other rare earth metalsCompared with the earth silicate materials (such as ytterbium silicate and the like), lutetium silicate has the characteristics of high melting point, good chemical stability and phase structure stability at high temperature and the like; the erbium silicate has good high-temperature stability, is well matched with the thermal expansion coefficient of the mullite and has good chemical compatibility with the mullite; through a large number of experimental researches, when the two rare earth silicates are matched and used according to the components in a gradient manner, the obtained environment barrier coating has better high-temperature protection effect, longer service life and more excellent high-temperature water-oxygen corrosion resistance, and the gradient ceramic layer or the single-component Lu in other molar ratios₂SiO₅Or Er₂SiO₅The thermal shock resistance life and the high-temperature water-oxygen corrosion resistance of the silicate coating are required to be further improved.

(3) The gradient environment barrier coating (gradient multilayer environment barrier coating) is quickly and integrally prepared in a low-pressure inert gas environment by a low-pressure plasma spraying technology, and the gradient environment barrier coating prepared by the method has long thermal shock resistance life and excellent high-temperature water-oxygen corrosion resistance; the integrated preparation process can further effectively relieve the problem of unmatched thermal expansion coefficients between the rare earth silicate gradient coating and the substrate, and avoids the generation of internal defects of the coating, so that the prepared gradient environmental barrier coating is more effectively ensured to have excellent high-temperature protection effect, longer service life, and more excellent thermal shock resistance and high-temperature water-oxygen corrosion resistance; the method of the invention is preferably that Lu is deposited on the surface of the mullite layer under the conditions of low pressure and high power₂SiO₅-Er₂SiO₅The gradient ceramic layer and low-pressure high-power plasma spraying technology is used for carrying out high-power spraying in a low-pressure inert gas environment, the jet flow temperature is high, the speed is high, the deposition efficiency is high, the cost is low, the coating is uniform, and the like, so that the rapid and integrated preparation of the multilayer environmental barrier coating is realized.

Drawings

The drawings of the present invention are provided for illustrative purposes only, and the proportions and dimensions of the layers in the drawings do not necessarily correspond to those of an actual product.

FIG. 1 is a schematic cross-sectional view of the gradient environmental barrier coating formed on a substrate material in accordance with one embodiment of the present invention.

In the figure: 1: a ceramic matrix composite; 2: a silicon adhesion layer; 3: a mullite layer; 4: lu (Lu)₂SiO₅-Er₂SiO₅A gradient ceramic layer.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

The present invention provides, in a first aspect, a gradient environmental barrier coating formed on a substrate material, for example, as shown in fig. 1, where fig. 1 is a schematic cross-sectional structure of the gradient environmental barrier coating formed on a substrate material according to an embodiment of the present invention.

In the invention, the gradient environmental barrier coating comprises a silicon bonding layer 2, a mullite layer 3 and Lu from a base material (such as a ceramic matrix composite material 1) to the outside in sequence ₂SiO₅-Er₂SiO₅A gradient ceramic layer 4. The Lu₂SiO₅-Er₂SiO₅The gradient ceramic layer comprises lutetium silicate (Lu) with different molar ratios₂SiO₅) And erbium silicate (Er)₂SiO₅) Lu made by mixing₂SiO₅-Er₂SiO₅Inner layer and Lu₂SiO₅-Er₂SiO₅And (4) an outer layer. Namely, in the invention, the gradient environmental barrier coating comprises a silicon bonding layer, a mullite layer and Lu from a base material to the outside in sequence₂SiO₅-Er₂SiO₅Inner layer and Lu₂SiO₅-Er₂SiO₅And (4) an outer layer. In the present invention, a rare earth silicate gradient ceramic coating (Lu)₂SiO₅-Er₂SiO₅Gradient ceramic layer) mainThe material is used for preventing water vapor from contacting with a matrix material (such as a ceramic matrix composite), improving the high-temperature water-oxygen corrosion resistance of the material and prolonging the high-temperature service life; in addition, the use of a mullite composition transition layer and a Si bond layer work together to alleviate the problem of mismatch in thermal expansion coefficients between the rare earth silicate gradient coating and the base material (substrate).

In the invention, the gradient environment barrier coating is also referred to as a gradient multilayer environment barrier coating, the silicon bonding layer is also referred to as a Si bonding layer, the mullite layer is also referred to as a mullite transition layer or a mullite component transition layer, and the Lu is also referred to as a Lu₂SiO₅-Er₂SiO₅The gradient ceramic layer is denoted as rare earth silicate gradient ceramic coating, Lu₂SiO₅-Er₂SiO₅The inner layer is denoted as Lu₂SiO₅-Er₂SiO₅A ceramic inner layer, said Lu being also used₂SiO₅-Er₂SiO₅The outer layer is marked as Lu₂SiO₅-Er₂SiO₅And (3) a ceramic outer layer.

According to some preferred embodiments, the Lu is a Lu₂SiO₅-Er₂SiO₅In the inner layer, the molar ratio of lutetium silicate to erbium silicate is (0.8-1.2): 1 (e.g., 0.8:1, 0.85:1, 0.9:1, 1:1, 1.05:1, 1.1:1, 1.15:1 or 1.2:1), preferably 1: 1; and/or in the Lu₂SiO₅-Er₂SiO₅In the outer layer, the molar ratio of lutetium silicate to erbium silicate is (3.5-4.5): 1 (e.g., 3.5:1, 3.6:1, 3.7:1, 3.8:1, 3.9:1, 4:1, 4.1:1, 4.2:1, 4.3:1, 4.4:1, or 4.5:1), preferably 4: 1. The inventor finds that compared with other rare earth silicate materials (such as ytterbium silicate and the like), lutetium silicate has the characteristics of high melting point, good chemical stability and phase structure stability at high temperature and the like; the erbium silicate has good high-temperature stability, is well matched with the thermal expansion coefficient of the mullite and has good chemical compatibility with the mullite; through a large number of experimental researches, when the two rare earth silicates are matched and used according to the component gradients, the obtained environment barrier coating has better high-temperature protection effect, longer service life and high-temperature water-oxygen resistanceThe corrosion performance is more excellent, and the gradient ceramic layer or the Lu with single component under other molar ratios₂SiO₅Or Er₂SiO₅The thermal shock resistance life and the high-temperature water-oxygen corrosion resistance of the silicate coating are required to be further improved.

According to some preferred embodiments, the silicon bonding layer has a thickness of 60 to 100 μm (e.g., 60, 65, 70, 75, 80, 85, 90, or 100 μm); the thickness of the mullite layer is 60-100 μm (for example, 60, 65, 70, 75, 80, 85, 90 or 100 μm); and/or the Lu₂SiO₅-Er₂SiO₅The gradient ceramic layer has a thickness of 150 to 200 μm (e.g., 150, 155, 160, 165, 170, 175, 180, 185, 190, 195, or 200 μm). In the present invention, the Lu₂SiO₅-Er₂SiO₅Inner layer and the Lu₂SiO₅-Er₂SiO₅The thickness ratio of the outer layer may be, for example, (0.8 to 1.2):1, preferably 1: 1. In the present invention, the thickness of the silicon bonding layer is preferably 60 to 100 μm, and the thickness of the mullite layer is preferably 60 to 100 μm and Lu₂SiO₅-Er₂SiO₅The thickness of the gradient ceramic layer is preferably 150-200 mu m, and the silicon bonding layer and the mullite layer with the thickness can more effectively relieve the problem of mismatch of thermal expansion coefficients between the rare earth silicate gradient ceramic coating with the thickness of 150-200 mu m and the substrate; in the present invention, the Lu is preferred₂SiO₅-Er₂SiO₅The thickness of the gradient ceramic layer is 150-200 mu m, and the Lu with the thickness₂SiO₅-Er₂SiO₅The gradient ceramic layer has longer thermal shock resistance life and more excellent high-temperature water-oxygen corrosion resistance.

The present invention provides in a second aspect a method of preparing a gradient environmental barrier coating according to the present invention as defined in the first aspect, the method comprising the steps of:

(1) Silicon powder (Si powder), mullite powder and lutetium silicate powder (Lu) with different molar ratios₂SiO₅Powder) and erbium silicate powder (Er)₂SiO₅Powder) mixed Lu₂SiO₅-Er₂SiO₅Inner layer mixed powder A and Lu₂SiO₅-Er₂SiO₅Respectively loading the outer layer mixed powder B into a powder feeder of low-pressure plasma spraying equipment and drying; in the present invention, Lu is also used₂SiO₅-Er₂SiO₅The inner layer mixed powder A is recorded as Lu₂SiO₅-Er₂SiO₅Mixing the powders A, Lu₂SiO₅-Er₂SiO₅The outer layer mixed powder B is recorded as Lu₂SiO₅-Er₂SiO₅Mixing the powder B; in the present invention, for example, Si powder, mullite powder, Lu are selected₂SiO₅-Er₂SiO₅Mixed powder A (Lu)₂SiO₅And Er₂SiO₅The molar ratio is, for example, (0.8 to 1.2): 1) lu, Lu₂SiO₅-Er₂SiO₅Mixed powder B (Lu)₂SiO₅And Er₂SiO₅The molar ratio is, for example, (3.5 to 4.5): 1) respectively loading the four kinds of powder into a powder feeder of low-pressure plasma spraying equipment, heating the powder in the powder feeder to 65-75 ℃, and drying for 3-5 hours;

(2) fixing the base material on a rotating table in a spraying chamber (vacuum chamber) of low-pressure plasma spraying equipment; and

(3) sequentially preparing the silicon bonding layer, the mullite layer and the Lu on the surface of a base material by a low-pressure plasma spraying method₂SiO₅-Er₂SiO₅Inner layer and the Lu₂SiO₅-Er₂SiO₅An outer layer, whereby the gradient environmental barrier coating is produced on the surface of a base material; in the present invention, the Lu ₂SiO₅-Er₂SiO₅The gradient ceramic coating comprises Lu₂SiO₅-Er₂SiO₅Inner layer and the Lu₂SiO₅-Er₂SiO₅An outer layer; in the present invention, it is more preferable to deposit Lu on the surface of the mullite layer under low pressure and high power conditions₂SiO₅-Er₂SiO₅Inner layer and Lu₂SiO₅-Er₂SiO₅Outer layer, i.e. preferably by low pressure high power plasma spraying₂SiO₅-Er₂SiO₅Inner layer and Lu₂SiO₅-Er₂SiO₅And (4) an outer layer.

The invention adopts the low-pressure plasma spraying technology to prepare the gradient multilayer environmental barrier coating on the surface of a substrate material such as a ceramic matrix composite. The low-pressure plasma spraying is developed on the basis of atmospheric plasma spraying, a plasma spray gun, a rotary table, a sample piece, a mechanical arm and the like are placed in a sealed cabin which is low in vacuum and protected by inert gas, and coatings with different tissues and structures can be obtained by adjusting technological parameters such as power, vacuum degree, workpiece rotating speed, powder feeding rate and the like during spraying. Due to the high melting point of the rare earth silicate, the high-power spraying technology is preferably adopted in the invention when the rare earth silicate gradient coating is prepared. The invention preferably deposits Lu on the surface of the mullite layer under the conditions of low pressure and high power₂SiO₅-Er₂SiO₅The gradient ceramic layer and low-pressure high-power plasma spraying technology is used for carrying out high-power spraying in a low-pressure inert gas environment, the jet flow temperature is high, the speed is high, the deposition efficiency is high, the cost is low, the coating is uniform, and the like, so that the rapid and integrated preparation of the multilayer environmental barrier coating is realized.

The invention can quickly and integrally prepare the environmental barrier coating with excellent high-temperature water-oxygen corrosion resistance on the surface of the multi-element carbon and ceramic matrix composite, and the environmental barrier coating prepared by the invention has excellent thermal shock resistance, excellent high-temperature water-oxygen corrosion resistance and low weight loss rate of the material in a high-temperature water-oxygen corrosion resistance environment.

According to some preferred embodiments, before step (2), the method further comprises the steps of polishing and acetone cleaning treatment (pretreatment) on the surface of the base material; for example, it is preferable to polish the surface of the base material with 400# sandpaper, 800# sandpaper, 1200# sandpaper, and then ultrasonically clean the base material in an acetone solution for 10 to 20 min.

According to some preferred embodiments, the temperature of the drying treatment is 65 to 75 ℃ (e.g., 65 ℃, 70 ℃ or 75 ℃), and the time of the drying treatment is 3 to 5 hours (e.g., 3, 3.5, 4, 4.5 or 5 hours).

According to some preferred embodiments, in the process of preparing the gradient environmental barrier coating, the surface of the base material is heated by adopting a plasma jet heating mode to be 700-800 ℃, so that the binding force between the coating and the base material can be improved; specifically, in the present invention, the respective coating layers (silicon bonding layer, mullite layer, Lu) are prepared by a low-pressure plasma spraying method ₂SiO₅-Er₂SiO₅Inner layer and Lu₂SiO₅-Er₂SiO₅Outer layer), before spraying operation, plasma jet is adopted to heat the surface of a matrix material matrix to 700-800 ℃, so that the binding force between the coating and the base material is improved; preferably, plasma jet is continuously heated in the whole preparation process of the gradient environmental barrier coating so that the temperature of the surface of the base material is 700-800 ℃, and the bonding force between each layer of coating and the base material in the preparation process is improved. In the present invention, all base materials, with or without a coating layer prepared, are used as a base material (substrate) before the next coating layer is prepared.

According to some preferred embodiments, the Lu is prepared by low pressure plasma spraying under high power conditions₂SiO₅-Er₂SiO₅Inner layer and the Lu₂SiO₅-Er₂SiO₅Outer layer, preferably, the Lu is prepared₂SiO₅-Er₂SiO₅Inner layer and the Lu₂SiO₅-Er₂SiO₅The spraying power of the outer layer is 75-80 kW (for example, 75 or 80 kW). The invention preferably deposits the Lu on the surface of the mullite layer under the conditions of low pressure and high power₂SiO₅-Er₂SiO₅The gradient ceramic layer is sprayed at high power in a low-pressure inert gas environment by a low-pressure high-power plasma spraying technology, the jet flow temperature is high, the speed is high, the deposition efficiency is high, the cost is low, the coating is uniform, the rapid and integrated preparation of the multilayer environmental barrier coating is realized, and the prepared gradient environmental barrier coating is ensured to be excellent The high-temperature protection effect is longer, the service life is longer, and the thermal shock resistance and the high-temperature water-oxygen corrosion resistance are more excellent.

According to some preferred embodiments, the absolute pressure in the spray chamber (vacuum chamber) during the preparation of the gradient environmental barrier coating is 5 x 10³～7×10³Pa. In the invention, for example, before spraying, the vacuum chamber is vacuumized until the absolute pressure in the vacuum chamber is 100-200 Pa, and then argon is filled into the vacuum chamber until the absolute pressure in the vacuum chamber is 5 x 10³～7×10³Pa。

According to some preferred embodiments, in the process of preparing the silicon bonding layer, argon (Ar) and helium (He) are used as plasma gases, the flow rate of argon is 20 to 50L/min (e.g., 20, 25, 30, 35, 40, 45 or 50L/min), the flow rate of helium is 2 to 15L/min (e.g., 2, 4, 6, 8, 10, 12 or 15L/min), the spraying distance is 200 to 500mm (e.g., 200, 250, 300, 350, 400, 450 or 500mm), the rotation speed of the turntable is 3 to 10r/min (e.g., 3, 4, 5, 6, 7, 8, 9 or 10r/min), the arc voltage of a low-pressure plasma spraying device is 10 to 20V (e.g., 10, 12, 14, 16, 18 or 20V), the arc current is 400 to 700A (e.g., 400, 450, 500, 550, 600, 650 or 700A), and the powder feeding rate of silicon powder is 10 to 20g/min (e.g., 10 to 20 g., 10 g/min), 11. 12, 13, 14, 15, 16, 17, 18, 19 or 20 g/min). In the present invention, the powder feeding mode is the powder feeding inside the spray gun. In the present invention, the rotation speed of the turntable is the rotation speed of the substrate.

According to some preferred embodiments, in the process of preparing the mullite layer, argon and helium are used as plasma gases, the flow rate of argon is 20 to 50L/min (for example, 20, 25, 30, 35, 40, 45 or 50L/min), the flow rate of helium is 10 to 20L/min (for example, 10, 12, 14, 16, 18 or 20L/min), the spraying distance is 400 to 700mm (for example, 400, 450, 500, 550, 600, 650 or 700mm), the rotation speed of the rotating table is 3 to 10r/min (for example, 3, 4, 5, 6, 7, 8, 9 or 10r/min), the arc voltage of a low-pressure plasma spraying device is 20 to 40V (for example, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38 or 40V), the arc current is 1000 to 1300A (for example, 1000, 1100, 1150, 1200, mullite, 1250 or 1300A), and the powder feeding rate of mullite powder is 20 to 30g/min (for example, 20 to 30g/min), 21. 22, 23, 24, 25, 26, 27, 28, 29, or 30 g/min).

According to some preferred embodiments, in the preparation of the Lu₂SiO₅-Er₂SiO₅Inner layer and/or the Lu₂SiO₅-Er₂SiO₅In the process of the outer layer, argon and helium are used as plasma gases, the flow rate of argon is 20-50L/min (for example, 20, 25, 30, 35, 40, 45 or 50L/min), the flow rate of helium is 30-60L/min (for example, 30, 35, 40, 45, 50, 55 or 60L/min), the spraying distance is 400-700 mm (for example, 400, 450, 500, 550, 600, 650 or 700mm), the rotating speed of the rotating table is 5-15 r/min (for example, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or 15r/min), the arc voltage of a low-pressure plasma spraying device is 35-40V (for example, 35, 38 or 40V), the arc current is 2000-2200A (for example, 2000, 2050, 2100, 2150 or 2200A), the spraying power is 75-80 kW (for example, 75 or 80kW), and Lu is ₂SiO₅-Er₂SiO₅Inner layer mixed powder A and/or Lu₂SiO₅-Er₂SiO₅The powder feeding rate of the outer layer mixed powder B is 30-40 g/min (for example, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39 or 40 g/min).

The method of the invention is preferably used for preparing the silicon bonding layer, the mullite layer and the Lu₂SiO₅-Er₂SiO₅The technological parameters of the low-pressure plasma spraying are adjusted and optimized in the process of the gradient ceramic layer, so that the deposition speed of the coating is higher, the deposition efficiency is higher, and the coatings of all layers are more uniform.

According to some preferred embodiments, the particle size of the silicon powder is 3-10 μm; the particle size of the mullite powder is 5-30 mu m; and/or Lu₂SiO₅-Er₂SiO₅Inner layer mixed powder A and/or Lu₂SiO₅-Er₂SiO₅The particle size of the outer layer mixed powder B is 10-40 μm. In the invention, the silicon powder, the mullite powder and the Lu₂SiO₅-Er₂SiO₅Inner layer mixed powder A and Lu₂SiO₅-Er₂SiO₅The outer layer mixed powder B is preferably hollow spherical micron powder with the particle size within the range, so that the uniformity of each layer of coating is guaranteed, the bonding performance between the coatings is better, and the gradient environmental barrier coating with more excellent performance is obtained.

According to some embodiments, the method of preparing a gradient environmental barrier coating of the present invention comprises the steps of:

(a) Selecting Si powder, mullite powder and Lu₂SiO₅-Er₂SiO₅Mixed powder A (Lu)₂SiO₅And Er₂SiO₅The molar ratio of (0.8-1.2): 1) lu, Lu₂SiO₅-Er₂SiO₅Mixed powder B (Lu)₂SiO₅And Er₂SiO₅The molar ratio of (3.5-4.5): 1) and respectively loading the four kinds of powder into a powder feeder of low-pressure plasma spraying equipment, heating the powder in the powder feeder to 65-75 ℃, and drying for 3-5 hours.

(b) Pretreating the surface of the ceramic matrix composite substrate; and sequentially polishing the surface of the base material by using 400#, 800# and 1200# sandpaper, and then ultrasonically cleaning in an acetone solution for 10-20 min.

(c) Before spraying, the vacuum chamber of the low-pressure plasma spraying equipment is vacuumized to 100-200 Pa, and then argon is filled to 5 multiplied by 10³～7×10³Pa, igniting the plasma spray gun.

(d) The plasma jet is used for heating the base material, so that the surface temperature of the material is increased.

(e) And depositing a Si bonding layer on the surface of the ceramic matrix composite.

(f) And depositing a mullite component transition layer on the surface of the Si bonding layer.

(g) Spraying Lu on the surface of the mullite transition layer₂SiO₅-Er₂SiO₅Inner layer, coating medium Lu₂SiO₅And Er₂SiO₅The molar ratio of the components is (0.8-1.2): 1.

(h) lu spray coating₂SiO₅-Er₂SiO₅Outer layer, coating in Lu₂SiO₅And Er₂SiO₅The molar ratio of the components is (3.5-4.5): 1.

in a third aspect, the present invention provides a composite material (e.g., a ceramic matrix composite material) comprising the gradient environmental barrier coating of the first aspect of the present invention or the gradient environmental barrier coating produced by the method of manufacture of the second aspect of the present invention.

The present invention will be further described with reference to the following examples. These examples are merely illustrative of preferred embodiments of the present invention and the scope of the present invention should not be construed as being limited to these examples.