High-entropy bisilicate environmental barrier coating resistant to high-temperature water vapor and preparation method of high-entropy bisilicate environmental barrier coating

Abstract

The invention belongs to the technical field of environmental barrier coatings, and discloses a high-entropy bisilicate environmental barrier coating resistant to high-temperature water vapor and a preparation method of the environmental barrier coating, the molecular formula of the environmental coating is (RE) 2Si2O7, RE is equal to a combination of Yb, Y, Er, Lu and Sc in an equal molar ratio, and the preparation method of the environmental coating comprises the steps that slurry is mixed, the slurry is sintered and then sprayed, and spherical agglomerated powder is obtained; the spherical agglomerated powder is sintered, and (5RE1 / 5) 2Si2O7 spraying powder is obtained; roughening the surface of the substrate; the preparation method comprises the following steps: preparing a Si bonding layer on a substrate by adopting an atmospheric plasma spraying technology, spraying (5RE1 / 5) 2Si2O7 on the substrate by adopting the atmospheric plasma spraying technology, and finally carrying out heat treatment and cooling in an argon protective atmosphere to obtain a final environmental barrier coating. The method is suitable for preparing the aero-engine environmental barrier coating.

Description

Technical Field

[0001] The present invention relates to the technical field of environmental barrier coatings, and in particular to a high-entropy bisilicate environmental barrier coating resistant to high-temperature water vapor and a preparation method thereof. Background Art

[0002] Aircraft engines are developing towards high thrust-to-weight ratio and high thermal engine efficiency, which requires continuous improvement of engine turbine inlet temperature and structural weight reduction. Ceramic-based composites have the advantages of low density and high specific strength, and can be used for hot end components of engines. However, during the service of ceramic-based composites, ceramic-based composites will be corroded by high-temperature water vapor generated by fuel combustion, resulting in material performance degradation or even failure. Therefore, in order to improve the problem of insufficient water vapor resistance of ceramic-based composites, the present invention proposes a high-entropy double silicate environmental barrier coating that is resistant to high-temperature water vapor, thereby effectively improving the ability of ceramic-based materials to resist water vapor corrosion. Summary of the invention

[0003] The present invention aims to provide a high-entropy bisilicate environmental barrier coating resistant to high-temperature water vapor and a preparation method thereof, so as to solve the problem that the existing ceramic-based materials have insufficient water vapor resistance.

[0004] In order to achieve the above object, the present invention provides the following technical solutions:

[0005] A high-entropy double silicate environmental barrier coating resistant to high-temperature water vapor and a preparation method thereof, wherein the molecular formula of the environmental barrier coating is (RE)2Si2O7, wherein RE=a combination of Yb, Y, Er, Lu, Sc in a molar ratio, and the environmental barrier coating is based on SiCf / SiC;

[0006] The preparation method of the environmental barrier coating is as follows:

[0007] S1. Add RE2O3 powder, SiO2 powder, water, anhydrous ethanol and ball milling beads into a spherical inkjet mill and mix to obtain a uniformly mixed slurry; after obtaining the slurry, heat treat at 1480°C for 2h, then sieve through 100 mesh, spray granulate, and finally sieve through 100 mesh to obtain spherical agglomerated granulated powder with a particle size of 20um to 75um;

[0008] S2, the obtained spherical agglomerated powder was placed in a pressureless sintering furnace for calcination at 1480°C for 2h to obtain (5RE 1 / 5 )2Si2O7 spray powder;

[0009] S3, cleaning and roughening the SiCf / SiC substrate to make the roughness of the surface to be sprayed reach 25um to 50um;

[0010] S4, preparing a Si bonding layer on the substrate by using atmospheric plasma spraying technology;

[0011] S5, using atmospheric plasma spraying technology to (5RE 1 / 5 )2Si2O7 spray powder is sprayed onto the Si bonding layer, and then sprayed (5RE 1 / 5 )2Si2O7, the SiCf / SiC substrate is placed in an argon protective atmosphere for heat treatment and cooled to obtain the environmental barrier coating on the SiCf / SiC substrate.

[0012] Furthermore, in step S4, the raw material of the Si bonding layer is Si powder, and the particle size of the Si powder is 10 um to 100 um.

[0013] Furthermore, in step S4, the parameters for preparing the Si bonding layer on the substrate using atmospheric plasma spraying technology are set to: current 700A~800A, voltage 40V~43V, argon flow rate 20slm~40slm, helium flow rate 80slm~100slm, spraying distance 80mm~120mm, and powder feeding rate 2rpm~4rpm.

[0014] Further, in step S5, the atmospheric plasma spraying process parameters are: current 800A-900A, voltage 40V-43V, argon flow rate 40slm-60slm, helium flow rate 80slm-100slm, spraying distance 80mm-120mm, powder feeding rate 2rpm-4rpm.

[0015] Beneficial effects of the technical solution: the high-entropy rare earth silicate material prepared by the present invention can form a stable single-phase solid solution, the elements in the powder are evenly distributed, and the structure is dense; the environmental barrier coating prepared by the present invention can effectively avoid the oxidation and performance degradation of the SiCf / SiC matrix at high temperature, and has good resistance to high-temperature water vapor corrosion; the spray powder preparation process adopted by the present invention has the advantages of low cost, high powder purity, high preparation efficiency, and suitability for batch preparation; the coating preparation method adopted by the present invention is a plasma spraying method, which has the advantages of fast deposition speed, low cost, good repeatability, a large adjustable range of coating spray thickness, high production efficiency, and suitability for large-scale production compared to the existing brush coating method. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is the XRD diagram of each state in the synthesis process of the present invention;

[0017] Figure 2 is the XRD diagram of the coating during corrosion of the present invention;

[0018] Figure 3 The surface morphology of the coating during the corrosion process of the coating of the present invention;

[0019] Figure 4 is a cross-sectional view of the coating during the corrosion process of the coating of the present invention; DETAILED DESCRIPTION

[0020] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments:

[0021] A high entropy double silicate environmental barrier coating resistant to high temperature water vapor, the molecular formula of which is (RE)2Si2O7, wherein RE=a combination of Yb, Y, Er, Lu, Sc and other molar ratios. The preparation method of the coating comprises the following steps:

[0022] S1. Add RE2O3 powder, SiO2 powder, water, anhydrous ethanol and ball milling beads into a spherical inkjet mill and mix to obtain a uniformly mixed slurry; after obtaining the slurry, heat treat at 1480°C for 2h, then sieve through 100 mesh, spray granulate, and finally sieve through 100 mesh to obtain spherical agglomerated granulated powder with a particle size of 20um to 75um;

[0023] S2, the obtained spherical agglomerated powder was placed in a pressureless sintering furnace for calcination at 1480°C for 2h to obtain (5RE 1 / 5 )2Si2O7 spray powder;

[0024] S3, cleaning and roughening the SiCf / SiC substrate to make the roughness of the surface to be sprayed reach 25um to 50um;

[0025] S4. Prepare a Si bonding layer on the substrate by atmospheric plasma spraying technology: the raw material of the Si bonding layer is Si powder, the particle size of the Si powder is 10um~100um, and the parameters for preparing the Si bonding layer are set as: current 700A~800A, voltage 40V~43V, argon flow rate 20slm~40slm, helium flow rate 80slm~100slm, spraying distance 80mm~120mm, powder feeding amount 2rpm~4rpm.

[0026] S5, using atmospheric plasma spraying technology to (5RE 1 / 5 )2Si2O7 spray powder is sprayed onto the Si bonding layer. The atmospheric plasma spraying process parameters are: current 800A~900A, voltage 40V~43V, argon flow 40slm~60slm, helium flow 80slm~100slm, spraying distance 80mm~120mm, powder feeding rate 2rpm~4rpm; then spray (5RE 1 / 5 )2Si2O7, the SiCf / SiC substrate is placed in an argon protective atmosphere for heat treatment and cooled to obtain the environmental barrier coating on the SiCf / SiC substrate.

[0027] The XRD patterns of various states during the synthesis process were obtained using an X-ray diffractometer, such as Figure 1 As shown by Figure 1 It can be seen that the diffraction peaks in the powder state are similar to those of the Yb2Si2O7 standard PDF card, which can prove that the powder was successfully prepared. The main phase of the coating in the sprayed state is composed of pyrosilicate. After annealing, the transformation from amorphous to crystalline is promoted.

[0028] The prepared environmental barrier coating was corroded in a quasi-static water-oxygen environment of 1400°C and 90% H2O-10% O2. The XRD patterns of the environmental coating were detected by X-ray diffractometer at 50h, 100h, 150h and 200h, and the surface morphology and cross-sectional images of the coating were recorded by scanning electron microscope.

[0029] like Figure 2 As shown, it is the XRD pattern during the corrosion process. Figure 2 It can be seen that with the increase of corrosion time, (5RE 1 / 5 )2Si2O7 phase proportion gradually decreases. When the corrosion time reaches 200h, (5RE 1 / 5 )2Si2O7 phase accounts for 52.56%.

[0030] like Figure 3 As shown, (5RE 1 / 5 )2Si2O7 coating surface morphology during corrosion process, from Figure 3 It can be seen that after 50h of corrosion, the coating surface was slightly corroded, and ridge-like areas and a small amount of corrosion pores appeared. With the increase of corrosion time, the corrosion pores gradually increased. After 200h of corrosion, a large number of corrosion pits can be observed on the coating surface, which indicates that in the high-temperature water vapor atmosphere, (5RE 1 / 5 )2Si2O7 undergoes phase transformation, and Si(OH)4 volatilizes to generate corrosion pores and corrosion pits.

[0031] like Figure 4 As shown, (5RE 1 / 5 )2Si2O7 coating cross-sectional view during corrosion process, from Figure 4 It can be seen that in the high-temperature water vapor corrosion atmosphere, the entropy edge of the surface layer is in closer contact with the atmosphere, so that the upper edge preferentially undergoes the transformation from pyrosilicate to monosilicate. Before corrosion, there are a few microcracks in the surface layer. When the corrosion time is 50h, there is a small amount of corrosion area on the upper edge of the surface layer. When the corrosion time is 100h, the corrosion pores gradually increase in the upper edge. With the increase of corrosion time, the corrosion area increases, and a loose and porous corrosion layer is gradually formed. After 150h of corrosion, (5RE 1 / 5The average corrosion depth of the 2Si2O7 coating is 6.83um. When the corrosion time reaches 200h, (5RE 1 / 5 )The average corrosion depth of the 2Si2O7 coating is 8.19um.

[0032] In summary, it can be seen that the high-entropy rare earth silicate material prepared by the present invention can form a stable single-phase solid solution, the coating and the substrate interface are well bonded and have no obvious defects, no oxygen channel is formed inside the environmental barrier coating, and the intrusion of oxygen and water vapor can be isolated, thus avoiding oxidation and performance degradation of the SiCf / SiC substrate at high temperatures, and having good resistance to high-temperature water vapor corrosion; at the same time, the elements in the coating are evenly distributed, the structure is dense, and there are no defects such as through cracks.

[0033] The above is only an embodiment of the present invention, and the common knowledge such as the known specific technical solutions or characteristics in the solution is not described in detail here. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the technical solution of the present invention, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A high-entropy double silicate environmental barrier coating resistant to high-temperature water vapor and a preparation method thereof, characterized in that: The molecular formula of the environmental barrier coating is (RE)2Si2O7, wherein RE=a combination of Yb, Y, Er, Lu, Sc and other molar ratios, and the environmental barrier coating is based on SiCf / SiC; The preparation method of the environmental barrier coating is as follows: S1. Add RE2O3 powder, SiO2 powder, water, anhydrous ethanol and ball milling beads into a spherical inkjet mill and mix to obtain a uniformly mixed slurry; after obtaining the slurry, heat treat at 1480°C for 2h, then sieve through 100 mesh, spray granulate, and finally sieve through 100 mesh to obtain spherical agglomerated granulated powder with a particle size of 20um to 75um; S2, the obtained spherical agglomerated powder was placed in a pressureless sintering furnace for calcination at 1480°C for 2h to obtain (5RE 1 / 5 )2Si2O7 spray powder; S3, cleaning and roughening the SiCf / SiC substrate to make the roughness of the surface to be sprayed reach 25um to 50um; S4, preparing a Si bonding layer on the substrate by using atmospheric plasma spraying technology; S5, using atmospheric plasma spraying technology to (5RE 1 / 5 )2Si2O7 spray powder is sprayed onto the Si bonding layer, and then sprayed (5RE 1 / 5 )2Si2O7, the SiCf / SiC substrate is placed in an argon protective atmosphere for heat treatment and cooled to obtain the environmental barrier coating on the SiCf / SiC substrate.

2. The method for preparing a high-entropy bisilicate environmental barrier coating resistant to high-temperature water vapor according to claim 1, characterized in that: In the step S4, the raw material of the Si bonding layer is Si powder, and the particle size of the Si powder is 10 um to 100 um.

3. The method for preparing a high-entropy bisilicate environmental barrier coating resistant to high-temperature water vapor according to claim 1, characterized in that: In step S4, the parameters for preparing the Si bonding layer on the substrate using atmospheric plasma spraying technology are set as follows: current 700A-800A, voltage 40V-43V, argon flow rate 20slm-40slm, helium flow rate 80slm-100slm, spraying distance 80mm-120mm, and powder feeding rate 2rpm-4rpm.

4. The method for preparing a high-entropy bisilicate environmental barrier coating resistant to high-temperature water vapor according to claim 1, characterized in that: In step S5, the atmospheric plasma spraying process parameters are: current 800A-900A, voltage 40V-43V, argon flow rate 40slm-60slm, helium flow rate 80slm-100slm, spraying distance 80mm-120mm, powder feeding rate 2rpm-4rpm.

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