CN109468568B - Rare earth silicate environmental barrier coating resisting crack expansion and preparation method thereof - Google Patents
Rare earth silicate environmental barrier coating resisting crack expansion and preparation method thereof Download PDFInfo
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- CN109468568B CN109468568B CN201710801357.3A CN201710801357A CN109468568B CN 109468568 B CN109468568 B CN 109468568B CN 201710801357 A CN201710801357 A CN 201710801357A CN 109468568 B CN109468568 B CN 109468568B
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- C23C4/00—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge
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Abstract
The invention relates to a rare earth silicate environmental barrier coating for preventing crack propagation and a preparation method thereofThe preparation method comprises the following steps that the rare earth silicate environmental barrier coating sequentially comprises a substrate, a bonding layer, a surface layer and an intermediate layer, wherein the bonding layer is positioned on the surface of the substrate, and the intermediate layer is positioned between the bonding layer and the surface layer; the bonding layer is a Si layer, and the middle layer is Yb2Si2O7A layer, the surface layer is rare earth monosilicate Re2SiO5. The coating designed by the invention adopts Yb2Si2O7The structure of the intermediate layer and the rare earth silicate as the surface layer has obvious crack expansion resistance and excellent thermal shock resistance.
Description
Technical Field
The invention relates to a rare earth silicate environmental barrier coating resisting crack propagation and a preparation method thereof, belonging to the field of coatings.
Background
High thrust-to-weight ratios are a significant indicator of high performance aircraft engines. The key to the development of the aero-engine towards high thrust-weight ratio and high efficiency is to improve the inlet temperature of fuel gas and reduce the structural mass. Silicon-based ceramic material comprising SiC, Si3N4C/SiC, SiC/SiC and the like, which are gradually replacing high-temperature alloys and are applied to hot end parts of high thrust-weight ratio aeroengines. However, during the long-term service of the aircraft engine, the silicon-based ceramic material is threatened by water vapor and corrosive impurities from the gas environment, so that the performance of the material is sharply reduced. The most practical and effective solution is to deposit an Environmental Barrier Coating (EBC) on the surface of the silicon-based ceramic material to form a Barrier between the substrate and the gas environment, thereby preventing the corrosive substances from corroding the substrate material and prolonging the service life of the component.
It has been found that rare earth silicates generally have a low coefficient of thermal expansion and good phase stability as well as excellent resistance to water vapor corrosion, and are the most potential environmental barrier coating materials. Some current reports on rare earth silicate environmental barrier coating material systems mainly include Si (bond coat layer) + rare earth silicate (top layer, e.g., Er)2SiO5、Yb2SiO5And Lu2SiO5、Yb2Si2O7Etc.) and Si (tie layer) + mullite (middle layer) + rare earth silicate (top layer, e.g. Er)2SiO5、Yb2SiO5And Lu2SiO5Etc.) [ 1K.N.Lee, D.S.Fox, N.P.Bansal, Rare earth silicate environmental barrier coatings for SiC/SiC composites and Si3N4ceramics, J.Eur.Ceram.Soc.2005,25(10):1705-1715.2B.T.Richards, H.N.G.Wadley, Plasma spray deployment of tri-layer environmental barrier coatings, J.Eur.Ceram.Soc.,2014,34(12): 3069-. However, studies have shown that, due to the large difference in thermal expansion coefficients, the Si/Rare earth silicate coating systems can develop cracks through the Rare earth silicate coating during thermal cycling, and the Si bond coat is oxidized by corrosive media, eventually leading to coating failure [ 1k.n.lee, d.s.fox, n.p.bansal, Rare earth silicate environmental barrier coatings for SiC/SiC composites and Si compositions [ ]3N4ceramics, J.Eur.Ceram.Soc.2005,25(10):1705-1715.3B.T.Richards, K.A.Young, F.D.Francqville, S.Sehr, M.R.Begley, H.N.G.Wadley, Response of specific diagnostic-silicon environmental barrier coatings thermal cycling in water boiler, Acta mater, 2016,106: 1-14.; to forSi/mullite/rare earth silicate coating material system, cracks were found to penetrate the surface layer and mullite layer during thermal cycling [ 4B.T.Richards, S.Sehr, F.de Franqueville, M.R.Begley, H.N.G.Wadley, Frature Mechanisms of porous monocrystalline architectural coatings during cyclic thermal exposure, Acta materials, vol.103, pp.448-460,2016.5B.T.Richards, M.R.Begley, and H.N.G.Wadlwad, mechanics of porous monocrystalline/polycrystalline/silicon structural coating during cyclic thermal exposure 2015 materials, vol.103, pp.448-460,2016.5B.T.Richards, J.R.Begley, and H.N.G.Wadlwad.4098, ceramic 4098 (C.4012).
Meanwhile, the mullite coating prepared by adopting the plasma spraying technology has the following defects: (1) the plasma sprayed mullite coating contains more amorphous phases, and the amorphous phases in the coating are crystallized (the crystallization temperature is about 1000 ℃) under the high-temperature environment in service, so that large volume change is generated, cracks are generated in the mullite coating, and the stability of the coating system is reduced; (2) the decomposition phenomenon of mullite during the spraying process produces Al2O3Phase of Al2O3The thermal expansion coefficient of the mullite is different (mullite: 5-6 multiplied by 10)-6K-1，Al2O3：7.2×10-6K-1) In thermal cycling, stress is concentrated in the coating and corrosive substances may penetrate into the coating through cracks, causing damage to the coating system, which also affects the stability of the coating system [ 2B.T. Richards, H.N.G.Wadley, Plasma spray disposition of three-layer environmental barrier coatings.J.Eur.Ceram.Soc., 34(12):3069-3083.5B.T.Richards, M.R.Begley, and H.N.G.Wadley, foams of inorganic particulate/porous/ceramic coating failure, thermal cycling, J.Amram.Soram.C., 98(12):4066-4075.6 K.N.Lellier, N.705. ceramic particulate, 2015.710. ceramic, J.Am.Soc., 3. carbide, 1995-3. J.3. carbide.
Disclosure of Invention
In view of the above problems, the present invention aims to provide a rare earth silicate environmental barrier coating resistant to crack propagation and a preparation method thereof.
On one hand, the invention provides a rare earth silicate environmental barrier coating, which sequentially comprises a substrate, a bonding layer, a surface layer and an intermediate layer, wherein the bonding layer is positioned on the surface of the substrate; the bonding layer is a Si layer, and the middle layer is Yb2Si2O7A layer, the surface layer is rare earth monosilicate Re2SiO5。
In the material system of the rare earth silicate environmental barrier coating provided by the invention, Si is used as a bonding layer (the thermal expansion coefficient is 3.5-4.5 multiplied by 10)-6K-1)，Yb2Si2O7As an intermediate layer (3.7-4.5X 10)-6K-1) Selecting a rare earth silicate Re having a higher coefficient of thermal expansion than the bonding layer and the intermediate layer2SiO5As the main component as the face layer. Wherein Si is a bonding layer and Yb2Si2O7The intermediate layer has a lower coefficient of thermal expansion than the base material and is subjected to compressive stress, and the facing layer (rare earth monosilicate Re)2SiO5) Is subjected to tensile stress, so that cracks generated in the surface layer of the coating system during thermal cycling cannot penetrate into Yb2Si2O7An intermediate layer. Can make full use of Yb2Si2O7Low thermal expansion coefficient, high-temp plasticity and rare-earth silicate (Re)2SiO5) The excellent steam corrosion resistance is combined, so that the system has the characteristics of good crack expansion resistance and thermal shock resistance, and the protective performance of the coating system can be further improved. In addition, Si has high-temperature plasticity, and has better physical and chemical compatibility with the rare earth silicate and the silicon-based ceramic material, so that the combination of the rare earth silicate and the silicon-based ceramic material can be improved.
Preferably, the rare earth monosilicate Re2SiO5Is selected from Y2SiO5、Sc2SiO5、Gd2SiO5、Er2SiO5、Tm2SiO5、Yb2SiO5、Lu2SiO5At least one of (a) and (b),preferably Yb2SiO5. In the invention, Y is2SiO5、Sc2SiO5、Gd2SiO5、Er2SiO5、Tm2SiO5、Yb2SiO5、Lu2SiO5At least one of them is used as main component as surface layer, and rare earth monosilicate Re is selected2SiO5Having a large coefficient of thermal expansion, in particular Yb2SiO5And Yb2Si2O7The chemical compositions of the two are similar, the chemical compatibility of the two is good, and the combination is more compact. Thus, in Yb2Si2O7The thermal stress between the coating and the matrix and the thermal stress between the coating and the matrix can be relieved (namely, the stress concentration in the coating in the thermal cycle process is relieved) by using the material as the intermediate layer material, the crack propagation resistance of the environmental barrier coating is improved (namely, the propagation of through cracks in the intermediate layer is prevented), and the thermal shock resistance and the service life of the coating are finally improved.
Preferably, the thickness of the bonding layer is 10 to 200 μm, preferably 10 to 100 μm.
Preferably, the thickness of the intermediate layer is 10-200 μm, and in order to ensure that the coating system has excellent crack propagation resistance and thermal shock resistance, the thickness is preferably 30-200 μm.
Preferably, the thickness of the surface layer is 10 to 200 μm, preferably 30 to 200 μm.
Preferably, the total thickness of the rare earth silicate barrier coating is more than 100 μm, preferably 100-500 μm.
Preferably, the matrix is SiC matrix or Si3N4One of a matrix, a C/SiC composite matrix and a SiC/SiC composite matrix.
In another aspect, the present invention provides a method for preparing the rare earth silicate barrier coating as described above, comprising:
(1) spraying Si powder on the surface of a base material by adopting a plasma spraying method to obtain a bonding layer;
(2) performing plasma spraying to Yb2Si2O7The powder is sprayed on a substrate with a bonding layer,forming an intermediate layer;
(3) adopting a plasma spraying method to spray rare earth monosilicate Re2SiO5And spraying the powder on a substrate with a bonding layer and an intermediate layer to obtain the rare earth silicate barrier coating.
Preferably, the particle size of the Si powder is 20 to 100 μm, and Yb is2Si2O7The particle diameter of the powder is 20-100 mu m, and Yb2SiO5The particle size of the powder is 20-100 μm.
Preferably, the matrix is pretreated by sand blasting coarsening, and the sand blasting pressure is 0.1-0.6 MPa.
Preferably, the parameters of the plasma spraying method include: plasma gas Ar: 35-55 slpm, preferably 35-48 slpm; powder carrier gas Ar: 2-7 slpm; plasma gas H2: 5-15 slpm, preferably 5-13 slpm; spraying distance: 90-200 mm; spraying power: 30-50 kw, preferably 30-45 kw; powder feeding rate: 10 to 35 r/min.
The environmental barrier coating of the present invention has several beneficial effects:
1. the coating designed by the invention adopts Yb2Si2O7The structure is that the middle layer and the rare earth silicate are surface layers, and compared with the existing single rare earth silicate coating and rare earth silicate/mullite double ceramic coating system, the structure has obvious crack expansion resistance and excellent thermal shock resistance;
2. yb produced by plasma spraying2Si2O7The coating is used as an intermediate layer and has the characteristics of low thermal expansion coefficient, less amorphous phase, less harmful impurity phase and good high-temperature stability;
3. the microstructure of the sprayed coating is uniform, the layers are well combined, and no through crack exists;
4. the invention has the advantages of simple process, low cost, high efficiency, good repeatability, controllable coating thickness, suitability for large-scale production and the like.
Drawings
FIG. 1 shows Si/Yb prepared in example 12Si2O7/Yb2SiO5A cross-sectional profile of the coating;
FIG. 2 shows Si/Yb prepared in example 12Si2O7/Yb2SiO5A macroscopic picture (a) of the original surface of the coating and a macroscopic picture (b) of the surface of the coating subjected to thermal shock for 40 times;
FIG. 3 shows Si/Yb prepared in example 12Si2O7/Yb2SiO5The cross-sectional topography of the coating is thermally shocked for 40 times;
FIG. 4 shows Si/Yb prepared in example 22Si2O7/Yb2SiO5Surface macro-photos of the original surface of the coating (a), 20 times of thermal shock (b), 30 times of thermal shock (c) and 40 times of thermal shock (d);
FIG. 5 shows Si/Yb prepared in example 22Si2O7/Yb2SiO5A cross-sectional profile of the coating after 20 thermal shocks;
FIG. 6 shows Si/Yb prepared in example 32Si2O7/Yb2SiO5Surface macro-photographs of the original surface of the coating (a), 20 times (b), 30 times (c) and 40 times (d);
FIG. 7 shows Si/Yb prepared in example 42Si2O7/Y2SiO5Surface macro-photographs of the original surface of the coating (a), 20 times (b), 30 times (c) and 40 times (d);
FIG. 8 shows Si/Yb prepared in example 52Si2O7/Er2SiO5Surface macro-photographs of the original surface of the coating (a), 20 times (b), 30 times (c) and 40 times (d);
FIG. 9 shows Si/Yb prepared in example 62Si2O7/Gd2SiO5Surface macro-photographs of the original surface of the coating (a), 20 times (b), 30 times (c) and 40 times (d);
FIG. 10 shows Si/Yb prepared in comparative example 12SiO5Surface macro-photographs of the original surface of the coating (a), 35 times of thermal shock (b) and 40 times of thermal shock (c);
FIG. 11 shows Si/Yb prepared in comparative example 12SiO5And (3) a cross-sectional profile of the coating layer subjected to thermal shock for 40 times.
Detailed Description
The present invention is further illustrated by the following examples, which are to be understood as merely illustrative and not restrictive.
The rare earth silicate environmental barrier coating (environmental barrier coating) has a compact structure, good bonding performance between coatings and between the coatings and a substrate, and obvious crack expansion resistance. The environmental barrier coating comprises a three-layer structure of a bonding layer, a middle layer and a surface layer except a substrate, and is shown in figure 1. The adhesive layer of the environmental barrier coating is a layer directly contacted with the substrate, the middle layer is a layer directly contacted with the adhesive layer, and the surface layer is a layer farthest away from the adhesive layer. The environment barrier coating is suitable for SiC matrix and Si3N4A matrix, a C/SiC composite matrix or a SiC/SiC composite matrix. The main body is Yb2Si2O7As the intermediate layer, Yb can be sufficiently utilized2Si2O7The thermal expansion coefficient is low (3.7-4.5X 10)-6K-1) The material has the advantage of high-temperature plasticity, so that the system has the characteristic of crack expansion resistance; simultaneously, with rare earth monosilicate (Re)2SiO5For example: y is2SiO5、Sc2SiO5、Gd2SiO5、Er2SiO5、Tm2SiO5、Yb2SiO5、Lu2SiO5At least 1) is used as an outer layer, the high-temperature steam corrosion resistance of the coating system can be further improved, and the service life is prolonged.
In the invention, the bonding layer material is Si, and the intermediate layer material is Yb2Si2O7The surface layer material is rare earth monosilicate ((Re)2SiO5For example: y is2SiO5、Sc2SiO5、Gd2SiO5、Er2SiO5、Tm2SiO5、Yb2SiO5、Lu2SiO5At least one of) the powder. Yb in the invention2Si2O7Thermal expansion coefficient of (3.7-4.5X 10)-6K-1) With an adhesive layer Si (3.5-4.5X 10)-6K-1) Close to and slightly less than the thermal expansion coefficient (4.5-5.5 multiplied by 10) of SiC, SiC/SiC and other matrix materials-6K-1) And at the same time is significantly lower than rare earth monosilicate (Re)2SiO5For example: y is2SiO5(5-6×10-6K-1)、Sc2SiO5(5-6×10-6K-1)、Gd2SiO5(7-11×10-6K-1)、Er2SiO5(7-8×10-6K-1)、Tm2SiO5(7-8×10-6K-1)、Yb2SiO5(7-8×10-6K-1)、Lu2SiO5(5-7×10-6K-1) Etc.) of the thermal expansion coefficient. When the thermal expansion coefficient of the coating is lower than that of the base material, the coating is subjected to compressive stress during thermal cycling; conversely, when the coating has a higher coefficient of thermal expansion than the base material, the coating is subjected to tensile stress during thermal cycling. The thickness of each layer of the rare earth silicate environmental barrier coating structure can be 10-200 mu m. The total thickness of the rare earth silicate environment barrier coating is more than 100 mu m, and more preferably 100 mu m to 500 mu m. Wherein the thickness of the bonding layer (Si layer) is preferably 10 to 100 μm. The thickness of the intermediate layer of the environmental barrier coating is preferably 30 to 200 μm. The surface layer of the environmental barrier coating preferably has a thickness of 30 to 200 μm.
The coating of the invention, including the bonding layer, the intermediate layer and the surface layer, is prepared by plasma spraying technology. The following is an exemplary description of the method for preparing the rare earth silicate environmental barrier coating provided by the present invention.
Preparation of powder: mixing Si powder and Yb2Si2O7Powder and rare earth monosilicate Re2SiO5And respectively sieving the powder to obtain powder with proper particle size, and respectively preparing the powder of each layer. The Si powder and Yb2Si2O7Powder and rare earth monosilicate Re2SiO5The particle size of the powder can be 20-100 μm.
Pretreatment of the substrate, i.e. spray pretreatment. Specifically, the surface of the substrate is pretreated and roughened by sand blasting. The matrix is selected from SiC and Si3N4C/SiC or SiC/SiC composite materials. Wherein the pretreatment step comprises: and (4) sandblasting and coarsening, wherein the sandblasting pressure is 0.1-0.6 MPa.
Preparation of a tie layer in an environmental barrier coating. Specifically, a bonding layer (e.g., Si layer) is formed on the surface of a base material by a plasma spraying method. Preparing a bonding layer, wherein the parameters of the plasma spraying process can comprise: plasma gas Ar: 35-48 slpm; powder carrier gas Ar: 2-7 slpm; plasma gas H2: 5-13 slpm; spraying distance: 90-200 mm; spraying power: 30-45 kw; powder feeding rate: 10 to 35 r/min.
Preparation of the intermediate layer in the environmental barrier coating. Adopting a plasma spraying method to prepare Yb2Si2O7The powder is sprayed onto a substrate with a bonding layer (e.g., a Si layer). The parameters of the plasma spraying process may include: plasma gas Ar: 35-55 slpm; powder carrier gas Ar: 2-7 slpm; plasma gas H2: 5-15 slpm; spraying distance: 90-200 mm; spraying power: 30-50 kw; powder feeding rate: 10 to 35 r/min.
Preparation of the top layer in the environmental barrier coating. Spraying the prepared rare earth monosilicate powder on the surface of the substrate with a bonding layer (Si layer) and an intermediate layer (Yb) by a plasma spraying method2Si2O7Layer) on the substrate, the environmental barrier coating is obtained. Wherein, the parameters of the plasma spraying process comprise: plasma gas Ar: 35-55 slpm; powder carrier gas Ar: 2-7 slpm; plasma gas H2: 5-15 slpm; spraying distance: 90-200 mm; spraying power: 30-50 kw; powder feeding rate: 10 to 35 r/min.
According to the invention, through reasonably designing and preparing the environmental barrier coating material system with a new structure, the thermal stress between the coating and between the coating and the matrix can be relieved, the crack expansion resistance of the environmental barrier coating is improved, and the thermal shock resistance and the service life of the environmental barrier coating are finally improved.
The present invention will be described in detail by way of examples. It is also to be understood that the following examples are illustrative of the present invention and are not to be construed as limiting the scope of the invention, and that certain insubstantial modifications and adaptations of the invention by those skilled in the art may be made in light of the above teachings. The specific process parameters and the like of the following examples are also only one example of suitable ranges, i.e., those skilled in the art can select the appropriate ranges through the description herein, and are not limited to the specific values exemplified below.
Example 1:
preparation of Si/Yb on SiC substrates2Si2O7/Yb2SiO5The coating structure is composed of 3 layers of materials, and the compositions from the inner layer to the outer layer are respectively as follows: bonding layer: si; an intermediate layer: yb of2Si2O7(ii) a Surface layer: yb of2SiO5。
The preparation steps of the coating are as follows:
step 1: mixing Si and Yb2Si2O7And Yb2SiO5Sieving the powder respectively, selecting the powder with the particle size of 20-100 mu m, and preparing the powder of each layer respectively;
step 2: carrying out sand blasting pretreatment on the surface of the SiC matrix, wherein the sand blasting pressure is 0.5 MPa;
and step 3: the Si powder with the appropriate particle size was sprayed onto the pretreated substrate using a plasma spray system (a-2000, Sulzer Metco AG, Switzerland), with the spray process parameters shown in table 1. The thickness of the coating is 50 μm;
table 1 shows the process parameters for atmospheric plasma spraying Si coatings:
| plasma gas Ar | 40slpm | Powder carrier gas Ar | 4slpm |
| Plasma gas H2 | 7slpm | Distance of spraying | 130mm |
| Spraying power | 37kw | Powder feeding rate | 20rpm |
Slpm: standard liters per minute;
and 4, step 4: the above Yb particles of suitable size were sprayed using a plasma spraying system (A-2000, Sulzer Metco AG, Switzerland)2Si2O7The powder is sprayed on a base material with a Si bonding layer, and the spraying process parameters are shown in Table 2. The thickness of the coating is 100 mu m;
and 5: the above Yb particles of suitable size were sprayed using a plasma spraying system (A-2000, Sulzer Metco AG, Switzerland)2SiO5Spraying the powder on the substrate with Si bonding layer and Yb2Si2O7The spraying process parameters on the substrate material of the intermediate layer are shown in table 2. The thickness of the coating is 100 mu m;
TABLE 2 plasma spray of Yb2Si2O7And Yb2SiO5 coating process parameters:
| plasma gas Ar | 43slpm | Powder carrier gas Ar | 5slpm |
| Plasma gas H2 | 12slpm | Distance of spraying | 130mm |
| Spraying power | 45kw | Powder feeding rate | 15rpm |
Slpm: standard liters per minute;
the cross section of the prepared coating is as shown in figure 1, the coating is a typical plasma spraying layered structure, the microstructure is uniform, and the coatings are tightly combined.
The coating is examined by a water quenching thermal shock method, and the conditions are as follows: the sample is kept warm for 20min in a 1400 ℃ tube furnace and then put into water with the temperature of about 25 ℃ for quenching. FIG. 2 shows the macro-topography of the sample before thermal shock ((a) in FIG. 2) and after 40 thermal shocks ((b) in FIG. 2). It can be seen that: after 40 times of thermal shock experiments, although the matrix is broken, the coating is kept complete, and the surface of the sample is not stripped. FIG. 3 is the cross-sectional profile of the sample after 40 times of thermal shock, and it can be seen that the longitudinal cracks generated during the thermal shock process penetrated Yb2SiO5Surface layer, but ends in Yb2Si2O7An intermediate layer; and Yb2SiO5Surface layer and Yb2Si2O7Good interlayer bonding, which indicates that Yb is in the coating system designed by the present invention2Si2O7The coating is an ideal intermediate layer material, and has good crack propagation resistance and thermal shock resistance.
Example 2:
this example differs from the coating described in example 1 in that: the matrix material is C/SiC composite matrix. The rest is the same as example 1.
It can be seen that the coating remained intact after 40 thermal shock experiments (T1400 ℃), and no flaking occurred on the sample surface (fig. 4 (d)). FIG. 5 is the cross-sectional profile of the sample after 20 times of thermal shock, and it can be seen that the longitudinal cracks formed during the thermal shock penetrated Yb2SiO5Surface layer, but ends in Yb2Si2O7An intermediate layer; and Yb2SiO5Surface layer and Yb2Si2O7Good interlayer bonding, which indicates that Yb is in the coating system designed by the present invention2Si2O7The coating is an ideal intermediate layer material, and has good crack propagation resistance and thermal shock resistance.
Example 3:
this example differs from the coating described in example 1 in that: the matrix material is SiC/SiC composite matrix. The rest is the same as example 1.
As shown in fig. 6, it can be seen that the coating layer remained intact after 40 thermal shock experiments (T1400 ℃), and no peeling phenomenon occurred on the surface of the sample ((d) in fig. 6). Longitudinal cracks generated during thermal shock terminate in Yb2Si2O7An intermediate layer. The coating system designed by the invention has good crack propagation resistance and thermal shock resistance.
Example 4:
this example differs from the coating described in example 1 in that: the matrix material is C/SiC composite matrix, and the surface material is Y2SiO5. Namely, Si/Yb is prepared on a C/SiC substrate2Si2O7/Y2SiO5And (4) coating.
As shown in fig. 7, it can be seen that the coating layer remained intact after 40 thermal shock experiments (T1400 ℃), and no peeling phenomenon occurred on the surface of the sample ((d) in fig. 7). Longitudinal cracks generated during thermal shock terminate in Yb2Si2O7An intermediate layer. The coating system designed by the invention has good crack propagation resistance and thermal shock resistance.
Example 5:
this example differs from the coating described in example 4 in that: the surface layer material is Er2SiO5. Namely, Si/Yb is prepared on a C/SiC substrate2Si2O7/Er2SiO5And (4) coating.
As shown in fig. 8, it can be seen that the coating layer remained intact after 40 thermal shock experiments (T1400 ℃), and no peeling phenomenon occurred on the surface of the sample ((d) in fig. 8). Longitudinal cracks generated during thermal shock terminate in Yb2Si2O7An intermediate layer. The coating system designed by the invention has good crack propagation resistance and thermal shock resistance.
Example 6:
this example differs from the coating described in example 4 in that: the surface layer material is Gd2SiO5. Namely, Si/Yb is prepared on a C/SiC substrate2Si2O7/Gd2SiO5And (4) coating.
As shown in fig. 9, it can be seen that the coating layer remained intact after 40 thermal shock experiments (T1400 ℃), and no peeling phenomenon occurred on the surface of the sample ((d) in fig. 9). Longitudinal cracks generated during thermal shock terminate in Yb2Si2O7An intermediate layer. The coating system designed by the invention has good crack propagation resistance and thermal shock resistance.
Comparative example 1:
the same plasma spraying process conditions as in example 1 were used to prepare Si/Yb on SiC substrates2SiO5The coating structure is as follows: i.e. spraying Si as a bonding layer and then spraying Yb alone2SiO5Coating with a thickness of 100 μm.
The obtained coating was subjected to the sameThermal shock experiments of conditions. It can be seen that the coating layer had a large area after being thermally shocked 35 times (FIG. 10 (b) and 40 times (FIG. 10 (c)) and that the longitudinal cracks formed during the thermal shock penetrated Yb2SiO5Layer, and Si bonding layer with Yb2SiO5Cracks also develop between the coatings. The coating performance was far inferior to that of Si/Yb prepared in example 12Si2O7/Yb2SiO5And (4) coating.
Claims (8)
1. The rare earth silicate environmental barrier coating is characterized by sequentially consisting of a substrate, a bonding layer positioned on the surface of the substrate, a surface layer and an intermediate layer positioned between the bonding layer and the surface layer, wherein the substrate is one of a C/SiC composite material substrate and a SiC/SiC composite material substrate;
the bonding layer is a Si layer, and the middle layer is Yb2Si2O7A layer, the surface layer is rare earth monosilicate Re2SiO5(ii) a The rare earth monosilicate Re2SiO5Is selected from Y2SiO5、Sc2SiO5、Gd2SiO5、Er2SiO5、Tm2SiO5、Yb2SiO5、Lu2SiO5At least one of; the thickness of the bonding layer is 10-200 mu m, the thickness of the middle layer is 10-300 mu m, and the thickness of the surface layer is 10-300 mu m;
the preparation method of the rare earth silicate barrier coating comprises the following steps:
(1) spraying Si powder on the surface of a base material by adopting a plasma spraying method to obtain a bonding layer;
(2) performing plasma spraying to Yb2Si2O7Spraying the powder on a substrate with a bonding layer to form an intermediate layer;
(3) adopting a plasma spraying method to spray rare earth monosilicate Re2SiO5Powder is sprayed onObtaining the rare earth silicate barrier coating on a substrate with a bonding layer and an intermediate layer;
the grain size of the raw material Si powder for the bonding layer is 20-100 mu m, and the raw material Yb for the middle layer2Si2O7The particle size of the powder is 20-100 mu m, and the raw material rare earth monosilicate Re for the surface layer2SiO5The particle size of the powder is 20-100 mu m; the parameters of the plasma spraying method include: plasma gas Ar: 35-55 slpm; powder carrier gas Ar: 2-7 slpm; plasma gas H2: 5-15 slpm; spraying distance: 90-200 mm; spraying power: 30-50 kw; powder feeding rate: 10 to 35 r/min.
2. The rare earth silicate environmental barrier coating of claim 1, wherein the bonding layer has a thickness of 10-100 μm.
3. The rare earth silicate environmental barrier coating of claim 1, wherein the thickness of the intermediate layer is 30-200 μm.
4. The rare earth silicate environmental barrier coating of claim 1, wherein the thickness of the top layer is 30-200 μm.
5. The rare earth silicate environmental barrier coating of claim 1, wherein the total thickness of the rare earth silicate barrier coating is greater than 100 μ ι η.
6. The rare earth silicate environmental barrier coating of claim 5, wherein the total thickness of the rare earth silicate barrier coating is 100-500 μm.
7. The rare earth silicate environmental barrier coating according to claim 1, wherein the substrate is pretreated by sand blasting for coarsening, and the sand blasting pressure is 0.1-0.6 MPa.
8. The rare earth silicate environmental barrier coating of claim 1, wherein the parameters of the plasma spray process include: plasma gas Ar: is 35-48 slpm; powder carrier gas Ar: 2-7 slpm; plasma gas H2: 5-13 slpm; spraying distance: 90-200 mm; spraying power: 30-45 kw; powder feeding rate: 10 to 35 r/min.
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| CN110330353B (en) | 2019-08-15 | 2020-03-13 | 中南大学 | SiCfFlame tube made of/SiC composite material and automatic preparation method thereof |
| CN111233498A (en) * | 2020-03-06 | 2020-06-05 | 中南大学 | Environmental barrier coating and preparation method and application thereof |
| CN112457061A (en) * | 2020-12-22 | 2021-03-09 | 中国科学院上海硅酸盐研究所 | Environment barrier coating with gradient change of components and preparation method thereof |
| CN114763598B (en) * | 2021-01-13 | 2024-03-08 | 中国科学院上海硅酸盐研究所 | Long-life environmental barrier coating and preparation method thereof |
| CN113278909B (en) * | 2021-05-25 | 2023-02-17 | 广东省科学院新材料研究所 | Thermal-environmental barrier coating and preparation method and application thereof |
| CN113463008A (en) * | 2021-06-29 | 2021-10-01 | 中国科学院上海硅酸盐研究所 | Crack expansion resistant environmental barrier coating and preparation method thereof |
| CN114276169A (en) * | 2021-12-30 | 2022-04-05 | 广东省科学院新材料研究所 | Self-healing high-density environmental barrier coating and preparation method and application thereof |
| CN115369348B (en) * | 2022-08-03 | 2024-02-06 | 中国科学院上海硅酸盐研究所 | Environment barrier coating with good high-temperature stability and preparation method thereof |
| CN115386823B (en) * | 2022-08-03 | 2024-03-08 | 中国科学院上海硅酸盐研究所 | Environmental barrier coating capable of resisting high-temperature vapor corrosion and CMAS corrosion and preparation method thereof |
| CN116715515B (en) * | 2023-06-08 | 2024-09-20 | 北京理工大学 | Lutetium monosilicate and environment barrier coating resistant to corrosion of calcium magnesium aluminum silicate and preparation method thereof |
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