A high-temperature resistant environmental barrier coating adhesive layer and its preparation method

Abstract

This invention provides a high-temperature resistant environmental barrier coating adhesive layer and its preparation method. The adhesive layer is composed of a mixed powder of HfSi2 particles and Si particles. The adhesive layer is obtained by atmospheric plasma spraying of the HfSi2 and Si mixed particles as thermal spray powder. This adhesive layer is used to sandwich an environmental barrier coating layer between the coating surface and a ceramic matrix composite material, with a thickness of approximately 30–80 μm. The preparation method includes the preparation of the thermal spray powder and atmospheric plasma spraying. The SiC substrate including this adhesive layer... f The environmental barrier coating of the / SiC composite matrix / HfSi2-Si adhesive layer / Yb2Si2O7 surface layer can be maintained for 100 hours in a water-oxygen coupling environment at 1350℃ without significant peeling.

Description

Technical Field

[0001] This invention relates to the field of environmental barrier coating materials for ceramic matrix composite surfaces, and particularly to a high-temperature resistant environmental barrier coating adhesive layer and its preparation method. Background Technology

[0002] With the continuous improvement of the thrust-to-weight ratio of aero engines, the turbine inlet temperature is constantly increasing, which creates an urgent need for materials for hot-end components that can withstand such harsh environments. For a long time, nickel-based superalloys have been the main materials for hot-end components of aero engines, but their temperature limit is only 1100℃, which cannot meet the requirements of the next generation of aero engines.

[0003] SiC f SiC composites possess low density, good high-temperature strength, creep resistance, and thermal stability, making them ideal materials to replace nickel-based superalloys in engine hot-section components. In dry environments, SiC... f The SiC composite material reacts with oxygen to form a dense layer of SiO2, which can block oxygen from reacting with SiC. f The SiC composite material undergoes further reaction. However, the combustion environment is a mixture of high-temperature water vapor and oxygen, etc., which affects SiC. f The SiO2 on the surface of the SiC composite material reacts with water vapor to generate volatile Si(OH)4 gas, which makes the SiC... f / SiC composite material was exposed to a high-temperature, water-vapor environment again, causing SiC f / SiC composites degrade rapidly.

[0004] Therefore, there is an urgent need for SiC f An environmental barrier coating (EBC) is prepared on the surface of the SiC composite material to resist corrosion from fuel gas over a long period of time.

[0005] After 30 years of development, the most mature EBCs to date consist of two parts: a binder layer and a topcoat. A few EBCs also include a mullite interlayer. The topcoat layer's function is to resist corrosive environments such as moisture, but it still has a certain oxygen permeability. Therefore, a binder layer is needed as a sacrificial layer. When exposed to an oxidizing environment, it forms a protective thermally grown oxide (TGO), thereby inhibiting oxygen erosion of the substrate. Secondly, the main function of the binder layer is to adjust the coefficient of thermal expansion between the substrate and the topcoat layer, playing a "bonding" role and improving the bonding strength between adjacent layers.

[0006] Currently, the most commonly used adhesive layer is the Si adhesive layer because of its low coefficient of thermal expansion (~3.5-4.5×10). -6 K-1 ), with SiC f The coefficients of thermal expansion of SiC composite materials are similar (~4.5-5.5×10⁻⁶). -6 K -1 ) and SiC f SiC composites are ideal for bonding layers due to their excellent chemical compatibility. However, the low melting point of Si (1414℃) limits the application temperature of EBCs to below 1350℃. Furthermore, the Si bonding layer exhibits poor toughness. In high-temperature, oxygen-containing environments, the Si bonding layer is oxidized to form SiO2 TGO. When the temperature cools to 240℃, SiO2 undergoes a phase transition from β-cristobalite to α-cristobalite, accompanied by a 4.5% volume shrinkage and a decrease in the coefficient of thermal expansion from ~3.1×10⁻⁶. -6 K -1 Increase to ~10×10 -6 K -1 These changes are extremely detrimental to the reliability and long-life application of EBCs systems. Therefore, developing novel high-temperature resistant adhesive layers is a crucial issue in the development of EBCs.

[0007] Some scholars have proposed introducing HfO2-modified Si as a binder layer. However, due to the oxygen permeability of HfO2 at high temperatures and its relatively high coefficient of thermal expansion, new problems arise with the HfO2-modified Si binder layer, including increased oxidation rate and mismatch in coefficients of thermal expansion. In addition, the poor chemical compatibility of HfO2 with the matrix material and the Si binder layer weakens the "bonding" effect of the binder layer. Summary of the Invention

[0008] To address the application limitations of traditional environmental barrier coating Si binders due to their low melting point, this invention provides a high-temperature resistant environmental barrier coating binder. The material is a mixture of HfSi2 and Si powder, with HfSi2 having a melting point of 1680℃. The aim is to modify the Si binder with HfSi2. The preparation method of this high-temperature resistant environmental barrier coating binder includes the preparation of thermally sprayed powder and atmospheric plasma spraying. The process is simple and can meet the increasing demand for high-temperature resistant materials in environmental barrier coating binders due to rising service temperatures.

[0009] The technical solution of the present invention is as follows: First, a high-temperature resistant environmental barrier coating adhesive layer is provided, which is used to be disposed between the environmental barrier coating surface layer and the ceramic matrix composite material. The thickness of the high-temperature resistant environmental barrier coating adhesive layer is 30-80 μm. The layer material of the high-temperature resistant environmental barrier coating adhesive layer includes a mixed powder of HfSi2 particles and Si particles. The high-temperature resistant environmental barrier coating adhesive layer is obtained by atmospheric plasma spraying in the form of thermal spray powder from the mixed powder of HfSi2 particles and Si particles.

[0010] Furthermore, the substrate of the aforementioned environmental barrier coating is SiC. f / SiC composite material, wherein the surface layer of the environmental barrier coating is ytterbium pyrosilicate, and the molecular formula of ytterbium pyrosilicate is Yb2Si2O7.

[0011] Furthermore, the HfSi2 layer material of the aforementioned high-temperature environmental barrier coating adhesive layer begins to oxidize at 1000℃ to form HfO2 and SiO2, and further begins to form HfSiO4 at 1400℃.

[0012] The present invention also provides a method for preparing the above-mentioned high-temperature resistant barrier coating adhesive layer, comprising the following steps:

[0013] S1. Using HfSi2 powder and Si powder as raw materials, a non-spherical mixed thermal spray powder of HfSi2 and Si is prepared by dry ball milling.

[0014] S2. Using HfSi2 powder, Si powder and deionized water as raw materials, ammonium citrate dispersant and gum arabic binder are added to prepare a slurry, and HfSi2 and Si spherical mixed thermal spray powder is obtained by centrifugal spray drying and granulation.

[0015] S3. Using an atmospheric plasma spraying method, the HfSi2 and Si mixed thermal spraying powder obtained in step S1 or S2 is sprayed onto the substrate surface of the environmental barrier coating to obtain a high-temperature resistant environmental barrier coating adhesive layer.

[0016] Furthermore, in step S1 above: the particle size range of HfSi2 powder is 0.1 to 20 μm, the particle size range of Si powder is 35 to 55 μm, the mass of Si powder is more than 10% of the total mass of powder, specifically 70%; the particle size of the grinding balls used in the dry ball milling process is 5 mm, the ball milling speed is 150 r / min, and the ball milling time is 1 hour.

[0017] Furthermore, in step S2 above: the particle size range of both HfSi2 powder and Si powder is 0.1-5 μm, the mass of Si powder is more than 10% of the total mass of powder, specifically 70%; the amount of ammonium citrate added is 0.8% of the total mass of powder, and the amount of gum arabic added is 2% of the total mass of powder; the mass ratio of powder to deionized water is (3:7) to (4:6); the drying temperature of the centrifugal spray dryer is 200℃, the centrifuge speed is 21000 r.pm, and the peristaltic pump feed rate is 35 rad / min; the particle size range of the spherical HfSi2 and Si mixed thermal spray powder is 20-100 μm.

[0018] Furthermore, in step S3 above: the arc current of atmospheric plasma spraying is 450-500A, the Ar gas flow rate is 35-40L / min, the H2 flow rate is 4.5-5.0L / min, the real-time spraying power is 25-30kW, and the spraying distance is 100-150mm; the thickness of the HfSi2 high-temperature resistant adhesive layer is 30-80μm.

[0019] The present invention also provides a high-temperature environmental barrier coating, which includes the above-mentioned high-temperature environmental barrier coating adhesive layer, and further includes a surface layer on the surface of the high-temperature environmental barrier coating adhesive layer and a SiC layer at the bottom of the high-temperature environmental barrier coating adhesive layer. f / SiC composite matrix.

[0020] Furthermore, the surface layer of the environmental barrier coating is ytterbium pyrosilicate, and the molecular formula of ytterbium pyrosilicate is Yb2Si2O7. The high-temperature resistant environmental barrier coating does not show significant peeling after 100 hours in a water-oxygen coupling environment at 1350℃.

[0021] Compared with the prior art, the advantages of the present invention are as follows:

[0022] 1) This invention uses HfSi2 as the second phase of the modified environmental barrier coating Si binder layer, and utilizes the high melting point of HfSi2 to overcome the disadvantage of the low melting point of traditional Si binder layers;

[0023] 2) This invention utilizes the reaction of HfSi2 with oxygen at high temperature, avoiding the oxygen permeation of the traditional dispersed phase HfO2 at high temperature, and improving the oxidation resistance of the adhesive layer;

[0024] 3) The adhesive layer of the present invention utilizes the silicide properties of HfSi2 to maintain good chemical compatibility with the Si adhesive layer;

[0025] 4) The raw materials for preparing the high-temperature resistant adhesive layer of this invention are readily available and can be prepared by centrifugal spray drying granulation and atmospheric plasma spraying, making the preparation method simple;

[0026] 5) This invention, based on the high-temperature resistant adhesive HfSi2 modified Si junction layer, further utilizes SiC... f HfSi2-Si / Yb2Si2O7 high-temperature resistant barrier coating was sequentially prepared on the / SiC composite matrix. This high-temperature resistant barrier coating showed no significant peeling after 100 hours in a water-oxygen coupling environment at 1350℃. Attached Figure Description

[0027] These and / or other aspects and advantages of the present invention will become clearer and more readily understood from the following detailed description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:

[0028] Figure 1 This is a schematic diagram of the high-temperature environmental barrier coating structure prepared according to an embodiment of the present invention;

[0029] Figure 2 The microstructure of the HfSi2 and Si spherical mixed thermal spray powder prepared in Example 1 of the present invention is shown in (a) low magnification observation and (b) high magnification observation.

[0030] Figure 3 The elemental distribution of Hf and Si in the HfSi2 and Si spherical mixed thermal spray powder prepared in Example 1 of the present invention is shown in (a) for Hf elemental distribution and (b) for Si elemental distribution.

[0031] Figure 4 The microstructures of the HfSi2 and Si non-spherical mixed thermal spray powder prepared in Example 1 of the present invention and the coating based on the powder are shown in (a) and (b) respectively.

[0032] Figure 5 In Embodiment 2 of the present invention, in SiC f The images of the HfSi2-Si / Yb2Si2O7 environmental barrier coating samples obtained on the / SiC composite material before and after 100h of water-oxygen corrosion are shown, where (a) is before water-oxygen corrosion and (b) is after water-oxygen corrosion.

[0033] Figure 6 The image shows the microstructure of the cross-section of the HfSi2-Si / Yb2Si2O7 environmental barrier coating prepared in Example 2 of this invention.

[0034] Figure 7 As shown in Comparative Example 1 of the present invention, in SiC f Photos of HfO2-Si / Yb2Si2O7 environmental barrier coating samples on / SiC composite material before and after 100h of water-oxygen corrosion, where (a) is before water-oxygen corrosion and (b) is after water-oxygen corrosion.

[0035] Figure 8 This is a cross-sectional microstructure of the HfO2-Si / Yb2Si2O7 environmental barrier coating prepared in Comparative Example 1 of this invention.

[0036] Figure 9 Comparative Example 2 of the present invention is based on SiC f Photos of Si / Yb2Si2O7 environmental barrier coating samples on SiC composite material before and after 100h of water-oxygen corrosion, where (a) is before water-oxygen corrosion and (b) is after water-oxygen corrosion.

[0037] Figure 10 The image shows the cross-sectional microstructure of the Si / Yb2Si2O7 environmental barrier coating prepared in Comparative Example 2 of this invention.

[0038] Figure 11Comparative Example 3 of the present invention is based on SiC f Photos of HfSi2 / Yb2Si2O7 environmental barrier coating samples on / SiC composite material before and after 20h of water-oxygen corrosion, where (a) is before water-oxygen corrosion and (b) is after water-oxygen corrosion. Detailed Implementation

[0039] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below through specific embodiments.

[0040] Example 1

[0041] The preparation of a thermal spray powder consisting of a mixture of HfSi2 and Si spherical particles includes the following steps:

[0042] S1. Using HfSi2 powder and Si powder with a particle size of 0.1-5μm as raw materials, with a mass ratio of 3:7, add ammonium citrate and gum arabic powder at 0.8% and 2% of the total powder mass, respectively, and add pure water at the same mass as the total powder mass. Stir evenly to obtain a slurry.

[0043] S2. While stirring, the slurry obtained in step S1 is fed into a centrifugal spray dryer. The drying temperature is set to 200℃, the centrifuge speed to 21000 r·pm, and the peristaltic pump feed rate to 35 rad / min. This yields a mixed thermal spray powder of HfSi2 and Si spherical particles with a particle size range of 35–75 μm.

[0044] Figure 2 and Figure 3 The images show the elemental distribution of the HfSi2 and Si spherical mixed thermal spray powder prepared in this embodiment. Figure 2 As shown, the HfSi2 and Si mixed thermal spray powder prepared using the granulation parameters of this embodiment consists of relatively large spherical particles, referred to as HfSi2 and Si spherical mixed thermal spray powder, which can better meet the requirements of plasma spraying for powder flowability. Figure 3 for Figure 2 (b) shows the elemental distribution. As can be seen from the figure, the Hf element is evenly distributed in the large spherical particles. This granulation process can achieve a better mixing effect of HfSi2 and Si powder.

[0045] The above-mentioned HfSi2 and Si mixed thermal spray powder can also be prepared by the following method, including the following steps:

[0046] HfSi2 powder with a particle size of 0.1–20 μm and Si powder with a particle size of 35–55 μm were used as raw materials. The mass ratio of the two was 3:7. After mixing, alumina grinding balls with a particle size of 5 mm were added. The mass of the grinding balls was twice the total mass of the powder. The grinding speed was 150 r / min and the grinding time was 1 h.

[0047] Figure 4 (a) shows the microstructure of the HfSi2 and Si mixed thermal spray powder prepared in this embodiment. It can be seen that it is non-spherical, and is called HfSi2 and Si non-spherical mixed thermal spray powder. In the figure, the dark large particles are Si, and the light small particles are HfSi2. HfSi2 is distributed around Si.

[0048] Using atmospheric plasma spraying, the above-mentioned HfSi2 and Si mixed thermal spray powder was sprayed onto the substrate surface of the environmental barrier coating to obtain a high-temperature resistant environmental barrier coating adhesive layer. Figure 4 (b) shows the microstructure of the coating produced by the non-spherical mixed thermal spray powder. The HfSi2 second phase is distributed in strips in the coating, and the dispersed distribution reduces the negative impact of the high thermal expansion coefficient of HfSi2. The continuous distribution of Si maintains the dense characteristics of the original Si bonding layer, reduces oxygen permeability, and maintains good bonding function.

[0049] Example 2

[0050] The preparation and high-temperature water-oxygen corrosion resistance assessment of an HfSi2 modified Si binder layer / Yb2Si2O7 topcoat environmental barrier coating includes the following steps:

[0051] S1. Using atmospheric plasma spraying technology, the HfSi2 and Si non-spherical mixed thermal spray powder prepared in Example 1 is sprayed onto SiC. f On the surface of the / SiC composite material, an HfSi2 modified Si bonding layer with a thickness of 50-75 μm was prepared, wherein the spraying parameters were: arc current of 450 A, Ar flow rate of 35 L / min, H2 flow rate of 5.0 L / min, and spray distance of 120 mm.

[0052] S2. Using atmospheric plasma spraying technology, a Yb2Si2O7 topcoat layer with a thickness of approximately 175–200 μm is sprayed onto the HfSi2 modified Si binder layer obtained in step S1, thus obtaining an HfSi2 modified Si binder layer / Yb2Si2O7 topcoat environmental barrier coating, labeled as HfSi2-Si / Yb2Si2O7 EBCs. The spraying process uses an arc current of 400 A, an Ar flow rate of 35 L / min, an H2 flow rate of 3.5 L / min, and a spray distance of 120 mm.

[0053] S3, the SiC obtained in step S4 f The / SiC composite material and the HfSi2-Si / Yb2Si2O7EBCs thereon were placed in a tube furnace under a nitrogen atmosphere and annealed at 1200℃ for 5 hours.

[0054] S4. Anneal the SiC from step S4 fThe / SiC composite material and the HfSi2-Si / Yb2Si2O7EBCs thereon were placed in a tube furnace at 1350℃. The test atmosphere was a high-temperature water-oxygen coupling atmosphere with a water vapor to oxygen volume ratio of 1:1. The samples were heated and cooled in the furnace: the heating rate from room temperature to 1000℃ was 4℃ / min, from 1000℃ to 1300℃ was 2℃ / min, and from 1300℃ to 1350℃ was 0.5℃ / min. Each heating period lasted 20 hours before cooling. The cooling rate from 1350℃ to 500℃ was 5℃ / min, followed by natural cooling. Five cycles of water-oxygen corrosion were performed for a total of 100 hours.

[0055] Figure 5 SiC was prepared for this embodiment. f Macroscopic morphology of / SiC composite material and HfSi2-Si / Yb2Si2O7 EBCs sample before and after 100h of water-oxygen corrosion, where (a) is before water-oxygen corrosion and (b) is after water-oxygen corrosion.

[0056] Figure 6 Microscopic morphology of the HfSi2-Si / Yb2Si2O7 EBCs cross section prepared for this embodiment.

[0057] Comparative Example 1

[0058] Preparation and high-temperature water-oxygen corrosion resistance assessment of an HfO2-modified Si binder / Yb2Si2O7 surface environmental barrier coating, labeled as HfO2-Si / Yb2Si2O7 EBCs. The preparation and performance assessment of the sample in this comparative example are consistent with Example 2, except that the HfSi2 raw material is replaced with HfO2.

[0059] Figure 7 SiC was prepared for this comparative example. f Macroscopic morphology of / SiC composite material and HfO2-Si / Yb2Si2O7 EBCs sample before and after 100h of water-oxygen corrosion, where (a) is before water-oxygen corrosion and (b) is after water-oxygen corrosion.

[0060] Figure 8 Microscopic morphology of the HfO2-Si / Yb2Si2O7 EBCs cross section prepared for this comparative example.

[0061] Comparative Example 2

[0062] Preparation and high-temperature water-oxygen corrosion resistance assessment of Si bonding layer / Yb2Si2O7 topcoat environmental barrier coating. Si thermal spray powder with a particle size of 35–55 μm was used. The preparation and assessment of the environmental barrier coating were consistent with Example 2, and the environmental barrier coating prepared in this comparative example is labeled as Si / Yb2Si2O7 EBCs.

[0063] Figure 9 SiC was prepared for this comparative example. f Macroscopic morphology of / SiC composite material and Si / Yb2Si2O7 EBCs sample before and after 100h water-oxygen corrosion, where (a) is before water-oxygen corrosion and (b) is after water-oxygen corrosion.

[0064] Figure 10 Microscopic morphology of Si / Yb2Si2O7 EBCs cross sections prepared for this comparative example.

[0065] Comparative Example 3

[0066] The preparation and high-temperature water-oxygen corrosion resistance evaluation of a novel HfSi2 adhesive layer / Yb2Si2O7 topcoat environmental barrier coating includes the following steps:

[0067] S1. Using HfSi2 powder with a particle size of 0.1-5μm as raw material, add ammonium citrate and gum arabic powder at 0.8% and 2% of the total powder mass, respectively, and add pure water at the same mass as the total powder mass. Stir evenly to obtain a slurry.

[0068] S2. While stirring, the slurry obtained in step S1 is fed into a centrifugal spray dryer. The drying temperature is set to 200℃, the centrifuge speed to 21000 r·pm, and the peristaltic pump feed rate to 35 rad / min. This yields HfSi2 spherical thermal spray powder with a particle size range of 35–75 μm.

[0069] S3. The preparation and evaluation of the environmental barrier coating are the same as in Example 2. The environmental barrier coating prepared in this comparative example is labeled as HfSi2 / Yb2Si2O7 EBCs.

[0070] Figure 11 SiC was prepared for this comparative example. f Macroscopic morphology of / SiC composite material and HfSi2 / Yb2Si2O7 EBCs sample before and after 20h of water-oxygen corrosion, where (a) is before water-oxygen corrosion and (b) is after water-oxygen corrosion.

[0071] Experimental Results Verification and Analysis

[0072] Example 2, Comparative Example 1, and Comparative Example 2 prepared environmental barrier coatings with different adhesive layers, namely HfSi2 modified Si, HfO2 modified Si, and Si adhesive layer, respectively. The macroscopic morphologies of the three before and after 100 h of water-oxygen corrosion at 1350℃ were as follows: Figure 5 , Figure 7 and Figure 9After 100 hours of water-oxygen corrosion at 1350℃, none of the three coatings showed significant peeling, proving that the HfSi2 modified Si adhesive layer and its high-temperature resistant coating system prepared in this invention have good adhesion, consistent with traditional Si adhesive layers and HfO2 modified Si adhesive layers.

[0073] The cross-sectional micromorphology of the coatings of HfSi2-Si / Yb2Si2O7 EBCs, HfO2-Si / Yb2Si2O7 EBCs and Si / Yb2Si2O7 EBCs after water-oxygen corrosion at 1350℃ for 100 h are as follows: Figure 6 , Figure 8 and Figure 10 After Si oxidation, SiO2 TGO is formed. The phase colors of the two are significantly different as shown in the figures. The location of SiO2 TGO formation differs after 100 hours of water-oxygen corrosion in different bonding layers. After prolonged water-oxygen corrosion, a distinct SiO2 TGO layer, approximately 10 μm thick, is formed in the Si bonding layer between the bonding layer and the Yb2Si2O7 surface layer. In the HfSi2-Si and HfO2-Si bonding layer samples, the SiO2 TGO mainly surrounds HfSi2 and HfO2, with a thickness of only 4–5 μm on the upper surface of both bonding layers.

[0074] HfO2 and HfSi2 are distributed in blocky and stripe-like patterns respectively within the binder layer. HfSi2 is not composed of a single phase; its outer periphery is white, while the center remains grayish-black. The blocky HfO2, however, exhibits excellent high-temperature phase stability. In the HfSi2-Si binder layer, both HfSi2 and the surrounding Si are oxidized. The HfSi2 within the HfSi2 particles is almost completely oxidized, forming white HfO2. Only a small amount of Si binder between the HfSi2 particles remains unoxidized. Similarly, in the HfO2-Si binder layer, the Si surrounding the HfO2 particles is oxidized, while the Si binder between the particles remains unoxidized. For the HfO2-Si binder layer, the HfO2 is O2. 2- In the conductor, some oxygen (O) is transported to the interior of the binder layer via HfO2. For the HfSi2-Si binder layer, HfSi2 has higher oxidation activity; therefore, HfSi2 particles oxidize before Si. In a high-temperature water-oxygen environment, oxygen reaches the HfSi2 particles, generating HfO2 that coats the HfSi2 particles and then diffuses throughout the entire binder layer.

[0075] Therefore, this invention uses HfSi2 to modify the Si binder layer. On the one hand, it utilizes the oxidation of HfSi2 in an aerobic environment, avoiding the high-temperature oxygen permeability of the existing dispersed phase HfO2; on the other hand, it utilizes the characteristics of HfSi2 as a silicide, avoiding the chemical incompatibility between the existing dispersed phase HfO2 and the Si binder layer. Compared with the original dispersed phase HfO2, the new HfSi2 modified phase proposed in this invention exhibits better oxidation resistance and is a more ideal dispersed phase for modifying the Si binder layer.

[0076] In Comparative Example 3, the adhesive layer was prepared entirely using HfSi2, forming HfSi2 / Yb2Si2O7 EBCs. Figure 11 The macroscopic morphology of the sample before and after 20 hours of water-oxygen corrosion at 1350℃ is shown in the figure. As can be seen from the figure, the coating exhibits "bulging" after annealing, and after 20 hours of high-temperature water-oxygen corrosion at 1350℃, the HfSi2 / Yb2Si2O7 EBCs are almost entirely detached. The HfSi2 binder layer has a large coefficient of thermal expansion, and HfSi2 oxidizes severely in the oxygen-containing environment, with the oxidation process accompanied by significant volume changes and intense exothermic reactions. Therefore, there is an upper limit to the amount of HfSi2 added as a second-phase modifier, and single-phase binders prepared using HfSi2 as a raw material are prone to coating failure.

[0077] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention, or modify them into equivalent embodiments, without departing from the scope of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention, without departing from the scope of the present invention, should fall within the protection scope of the present invention.

Claims

1. A high-temperature resistant environmental barrier coating adhesive layer, characterized in that, The high-temperature resistant environmental barrier coating adhesive layer is located between the environmental barrier coating surface layer and the ceramic matrix composite material, and the thickness of the high-temperature resistant environmental barrier coating adhesive layer is 30~80μm; The bonding layer material of the high-temperature environmental barrier coating is a mixed powder of HfSi2 particles and Si particles; The method for preparing the high-temperature resistant environmental barrier coating adhesive layer includes the following steps: S1. Using HfSi2 powder and Si powder as raw materials, a non-spherical mixed thermal spray powder of HfSi2 and Si is prepared by dry ball milling; the particle size range of HfSi2 powder is 0.1~20μm, the particle size range of Si powder is 35~55μm, and the mass of Si powder is 70% of the total mass of HfSi2 powder and Si powder; the particle size of the grinding balls used in the dry ball milling process is 5mm, the ball milling speed is 150r / min, and the ball milling time is 1h; S2. Using HfSi2 powder, Si powder, and deionized water as raw materials, ammonium citrate dispersant and gum arabic binder are added to prepare a slurry. The slurry is then granulated by centrifugal spray drying to obtain spherical mixed thermal spray powder of HfSi2 and Si. The particle size range of HfSi2 powder and Si powder is 0.1~5μm, and the mass of Si powder is 70% of the total mass of HfSi2 powder and Si powder. The amount of ammonium citrate added is 0.8% of the total mass of HfSi2 powder and Si powder, and the amount of gum arabic added is 2% of the total mass of HfSi2 powder and Si powder. The mass ratio of the total amount of HfSi2 powder and Si powder to deionized water is (3:7)~(4:6). The particle size range of the spherical mixed thermal spray powder of HfSi2 and Si is 20~100μm. S3. Using atmospheric plasma spraying, the HfSi2 and Si mixed thermal spraying powder obtained in step S1 or S2 is sprayed onto the substrate surface of the environmental barrier coating to obtain a high-temperature resistant environmental barrier coating adhesive layer with a thickness of 30~80μm. The arc current for atmospheric plasma spraying is 450~500A, the Ar flow rate is 35~40L / min, the H2 flow rate is 4.5~5.0L / min, the real-time spraying power is 25~30kW, and the spraying distance is 100~150mm.

2. The high-temperature environmental barrier coating adhesive layer as described in claim 1, characterized in that, The ceramic matrix composite material is a SiCf / SiC composite material, and the surface layer of the environmental barrier coating is ytterbium pyrosilicate with the molecular formula Yb2Si2O7.

3. The high-temperature environmental barrier coating adhesive layer as described in claim 2, characterized in that, In the adhesive layer of the high-temperature resistant environmental barrier coating, HfSi2 oxidizes at 1000℃ to form HfO2 and SiO2, and begins to form HfSiO4 at 1400℃.

4. A method for preparing a high-temperature environmental barrier coating adhesive layer as described in any one of claims 1-3, characterized in that, Includes the following steps: S1. Using HfSi2 powder and Si powder as raw materials, a non-spherical mixed thermal spray powder of HfSi2 and Si is prepared by dry ball milling; the particle size range of HfSi2 powder is 0.1~20μm, the particle size range of Si powder is 35~55μm, and the mass of Si powder is 70% of the total mass of HfSi2 powder and Si powder; the particle size of the grinding balls used in the dry ball milling process is 5mm, the ball milling speed is 150r / min, and the ball milling time is 1h; S2. Using HfSi2 powder, Si powder, and deionized water as raw materials, ammonium citrate dispersant and gum arabic binder are added to prepare a slurry. The slurry is then granulated by centrifugal spray drying to obtain spherical mixed thermal spray powder of HfSi2 and Si. The particle size range of HfSi2 powder and Si powder is 0.1~5μm, and the mass of Si powder is 70% of the total mass of HfSi2 powder and Si powder. The amount of ammonium citrate added is 0.8% of the total mass of HfSi2 powder and Si powder, and the amount of gum arabic added is 2% of the total mass of HfSi2 powder and Si powder. The mass ratio of the total amount of HfSi2 powder and Si powder to deionized water is (3:7)~(4:6). The particle size range of the spherical mixed thermal spray powder of HfSi2 and Si is 20~100μm. S3. Using atmospheric plasma spraying, the HfSi2 and Si mixed thermal spraying powder obtained in step S1 or S2 is sprayed onto the substrate surface of the environmental barrier coating to obtain a high-temperature resistant environmental barrier coating adhesive layer with a thickness of 30~80μm. The arc current for atmospheric plasma spraying is 450~500A, the Ar flow rate is 35~40L / min, the H2 flow rate is 4.5~5.0L / min, the real-time spraying power is 25~30kW, and the spraying distance is 100~150mm.

5. The method for preparing the high-temperature resistant adhesive layer according to claim 4, characterized in that, In step S2: The centrifugal spray dryer has a drying temperature of 200℃, a centrifuge speed of 21000rpm, and a peristaltic pump feed rate of 35rad / min.

6. A high-temperature resistant barrier coating, characterized in that, It includes the high-temperature environmental barrier coating adhesive layer as described in any one of claims 1-3, and further includes a surface layer on the surface of the high-temperature environmental barrier coating adhesive layer and a SiCf / SiC composite material matrix at the bottom of the high-temperature environmental barrier coating adhesive layer; the surface layer of the environmental barrier coating is ytterbium pyrosilicate, the molecular formula of ytterbium pyrosilicate is Yb2Si2O7, and the high-temperature environmental barrier coating does not peel off after 100 hours in a water-oxygen coupling environment at 1350℃.

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