An oxidation-resistant, long-life environmental barrier coating bond coat and method of making the same

Abstract

The application discloses an oxidation-resistant and long-life environmental barrier coating adhesive layer and a preparation method thereof, and belongs to the technical field of coating. The environmental barrier adhesive layer is a two-phase structure and is divided into an initial state and a heat-treated state. In the traditional Si-based phase, HfO2 with a similar thermal expansion coefficient to SiC is added, the HfO2 is dispersedly distributed in the continuous and dense Si-based phase, can react with the oxidation product of Si, forms HfSiO4 particles with excellent water-oxygen corrosion resistance and high toughness, and at the same time, coating heat treatment is carried out, a SiO2 film is formed on the surface of the coating, the oxygen vacancy concentration and the diffusion coefficient in the HfO2 are reduced, the HfSiO4 particles are dispersedly distributed in the SiO2 film, the phase change stress is accommodated, the crack propagation is prevented, and the service life is further improved, and the oxidation resistance and the long-life service of the novel adhesive layer are realized.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of coating, and particularly relates to an oxidation-resistant and long-life environmental barrier coating adhesive layer and a preparation method thereof. BACKGROUND

[0002] The environmental barrier coating (EBC) is a protective coating for protecting the SiC-based hot end part of an aero-engine, and is used for isolating water and oxygen corrosion. The current environmental barrier coating is composed of an adhesive layer and a surface layer. The existing adhesive layer material is pure Si, which has the advantages of similar thermal expansion coefficient to the substrate, good chemical compatibility, and excellent bonding. However, during service, the pure Si will be oxidized, and a hard and brittle SiO2 layer, i.e., a thermally generated oxide (TGO), is formed between the adhesive layer and the surface layer. The TGO layer will undergo phase transition at 220 DEG C, generating a phase transition stress, which leads to premature failure of the coating. The selection of the adhesive layer material should not only consider the good chemical compatibility with the substrate, but also have a low oxygen diffusion coefficient, a certain toughness, and if a second phase is doped, the interface bonding mode between the substrate and the second phase should be considered.

[0003] Although there is a report on the composite phase coating with the second phase HfO2 added in the current adhesive layer design, the method is to add the traditional second phase HfO2 for atmospheric plasma hybrid spraying, and no other treatment is performed. Only the Si composite phase adhesive layer with the single dispersed HfO2 is obtained. In addition, the Si composite phase adhesive layer with the dispersed HfO2 forms a single-phase SiO2 oxide film under the atmospheric condition, but the single-phase SiO2 oxide film will be broken due to the too high oxygen content in the atmosphere. Therefore, the method has the problems of fast oxygen diffusion, fast thickening of the oxide film, and easy peeling.

[0004] Therefore, the design of the environmental barrier adhesive layer with low oxidation rate and accommodating SiO2 phase transition stress can effectively improve the service life of the environmental barrier coating. SUMMARY

[0005] In order to overcome the above-mentioned defects of the prior art, the purpose of the present application is to provide an oxidation-resistant and long-life environmental barrier coating adhesive layer and a preparation method thereof, so as to improve the problems of fast oxygen diffusion, fast thickening of the oxide film, and easy peeling of the composite phase coating with the second phase HfO2 added in the traditional environmental barrier coating Si adhesive layer.

[0006] In order to achieve the above-mentioned purpose, the present application adopts the following technical scheme:

[0007] The first aspect of the present application discloses a preparation method of an oxidation-resistant and long-life environmental barrier coating adhesive layer, which adopts a vacuum plasma spraying technology to prepare an initial-state adhesive layer on the surface of a substrate, and performs heat treatment on the initial-state adhesive layer under an oxygen partial pressure environment of 0.1% to 1%, so as to obtain the oxidation-resistant and long-life environmental barrier coating adhesive layer.

[0008] The vacuum plasma sprayed powder is Si powder and HfO2 powder.

[0009] Preferably, the surface of the substrate is subjected to oil removal, sand blasting and preheating before vacuum plasma spraying.

[0010] Preferably, the heat treatment is vacuum heat treatment or inert atmosphere protection heat treatment.

[0011] In the second aspect of the present application, the oxidation-resistant and long-life environmental barrier coating adhesive layer prepared by the above method comprises: an initial-state adhesive layer of Si-doped HfO2 and a surface layer of SiO2-doped HfSiO4, which are sequentially stacked on the surface of the substrate.

[0012] Preferably, in the initial-state adhesive layer, HfO2 particles are dispersed in Si.

[0013] Preferably, in the initial-state adhesive layer, the mole fraction of HfO2 is 10% to 35%.

[0014] Preferably, in the initial-state adhesive layer, the particle size of HfO2 is 0.05 to 1.5 μm.

[0015] Preferably, in the initial-state adhesive layer, the aspect ratio of HfO2 is 1 to 2.

[0016] Preferably, in the surface layer, HfSiO4 particles are dispersed in SiO2.

[0017] Preferably, the average thickness of the oxidation-resistant and long-life environmental barrier coating adhesive layer is 50 to 300 μm.

[0018] Compared with the prior art, the present application has the following beneficial effects:

[0019] The application provides a preparation method of an oxidation-resistant and long-service-life environmental barrier coating adhesive layer, which comprises the following steps: firstly, an initial adhesive layer containing Si and HfO2 is prepared on the surface of a substrate by vacuum plasma spraying technology; HfO2 is similar to SiC in thermal expansion coefficient and is dispersedly distributed in the continuous and dense Si-based phase, which can react with the oxidation product of Si to form HfSiO4 particles with excellent water-oxygen corrosion resistance and high toughness, and the dispersed second-phase HfO2 doped in the initial adhesive layer can improve the toughness of the coating; and then, the initial adhesive layer is heat-treated, so that a continuous SiO2 film is formed on the surface of the initial adhesive layer by heating, the SiO2 film can reduce the oxygen vacancy concentration and diffusion coefficient of HfO2, thereby reducing the oxidation rate of the coating; meanwhile, the HfO2 on the surface of the initial adhesive layer reacts with the SiO2 film to form dispersed HfSiO4 particles, the HfSiO4 particles are dispersedly distributed in the SiO2 film to form a surface layer, can accommodate phase transition stress and prevent crack propagation, and can further improve the toughness and oxidation resistance of the coating and prolong the service life of the environmental barrier coating.

[0020] The application provides an oxidation-resistant and long-service-life environmental barrier coating adhesive layer, which comprises the following steps: an initial adhesive layer on the surface of a substrate is composed of Si and HfO2 similar to SiC in thermal expansion coefficient, and the dispersed HfO2 in the continuous and dense Si-based phase can improve the toughness of the coating; a surface layer on the surface of the initial adhesive layer is composed of SiO2 and HfSiO4, and the dispersed HfSiO4 particles in the SiO2 can accommodate phase transition stress and prevent crack propagation.

[0021] Further, if the content of HfO2 in the initial adhesive layer is too low, the content of generated HfSiO4 is too small, and the purpose of relieving SiO2 phase transition cannot be achieved; if the content of HfO2 in the initial adhesive layer is too high, the generated HfSiO4 is continuous, the second-phase strengthening effect is reduced, and the oxygen barrier capacity of the coating is reduced.

[0022] Further, when the particle size of the dispersed HfO2 in the initial adhesive layer is 0.05-1.5 mu m, the stress level in the whole coating can be lower.

[0023] Further, the aspect ratio of HfO2 in the initial adhesive layer is 1-2, and the dispersed particles are spherical or near-spherical, so that the stress concentration is smaller.

[0024] Further, the average thickness of the anti-oxidation, long-life environmental barrier coating adhesive layer is 50-300 μm, which can ensure that the thickness of the environmental barrier coating adhesive layer is not too thick to prevent excessive internal stress, and not too thin to prevent the function of adjusting the difference between the thermal expansion coefficients of the base and the surface layer. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 The environmental barrier adhesive layer section after vacuum heat treatment after APS spraying;

[0026] Figure 2 The fracture toughness detection results of bulk bodies with different HfO2 doping amounts (mole fraction) are compared;

[0027] Figure 3 The surface morphology comparison results of the environmental barrier coating adhesive layer bulk body prepared by the method after isothermal oxidation at 1370°C for 10h and 100h are shown in the figure; Si10Hf (a, b), Si20Hf (c, d), and Si30Hf (e, f);

[0028] Figure 4 The cross-sectional morphology comparison results of the environmental barrier coating adhesive layer bulk body prepared by the method after isothermal oxidation at 1370°C for 10h and 100h are shown in the figure; Si10Hf (a, b), Si20Hf (c, d), and Si30Hf (e, f). DETAILED DESCRIPTION

[0029] In order for those skilled in the art to understand the characteristics and effects of the present application, the following only describes and defines the terms and phrases mentioned in the specification and claims. Unless otherwise specified, all technical and scientific words used herein are the usual meanings understood by those skilled in the art for the present application, and in case of conflict, the definition in the specification shall prevail.

[0030] Theories or mechanisms described and disclosed herein, whether correct or not, should not in any way limit the scope of the present application, i.e., the present application can be practiced without being limited by any particular theory or mechanism.

[0031] In this paper, all features defined in the form of numerical range or percentage range, such as numerical value, quantity, content and concentration, are only for the sake of brevity and convenience. Therefore, the description of numerical range or percentage range should be considered as having covered and specifically disclosed all possible sub-ranges and individual numerical values (including integers and fractions) within the range.

[0032] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0033] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0034] This invention provides a method for preparing an antioxidant, long-life environmental barrier coating adhesive layer, the steps of which are as follows:

[0035] 1. An initial adhesive layer is prepared on the substrate surface using vacuum plasma spraying technology;

[0036] The vacuum plasma spraying powder sprayed in the initial adhesive layer is Si powder and HfO2 powder. The initial adhesive layer consists of a matrix phase and a dispersed phase. Si is the matrix phase with a particle size of 15-35 μm. The HfO2 phase is the dispersed phase, which is spherical or near-spherical in shape with an aspect ratio of 1-2 and a particle size of 0.05-1.5 μm, accounting for 10%-35% of the coating molar fraction. The dispersed phase is distributed inside the initial adhesive layer, and the HfO2 phase structure is monoclinic. The vacuum plasma spraying parameters are: vacuum degree of 100-135 Pa, spraying equipment current of 600-635 A, powder feeding speed of 14-20 g / min, and spraying distance of 150-180 mm.

[0037] 2. The initial adhesive layer is subjected to heat treatment under a low oxygen partial pressure environment to obtain an antioxidant, long-life environmental barrier coating adhesive layer;

[0038] The heat treatment is either vacuum heat treatment or inert atmosphere protection heat treatment. The surface structure (surface layer) of the anti-oxidation and long-life environmental barrier coating adhesive layer is a continuous SiO2 film with HfSiO4 particles dispersed inside. The average thickness of the anti-oxidation and long-life environmental barrier coating adhesive layer is 50-300 μm.

[0039] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0040] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0041] Example 1

[0042] This invention provides an antioxidant, long-life environmental barrier coating adhesive layer, such as... Figure 1 As shown, the adhesive layer is characterized by the following: in the top surface layer, HfSiO4 particles are dispersed within SiO2; in the initial state adhesive layer at the bottom of the surface layer, nearly spherical HfO2 particles are discretely distributed in the Si matrix phase, forming a dense structure; the molar fraction of HfO2 is 10%; the particle size is 0.05 μm; and the aspect ratio of HfO2 is 1–2.

[0043] The process flow is as follows:

[0044] Step 1: The substrate surface to be prepared with Si-based adhesive layer is degreased and sandblasted. For degreasing, an organic solvent is used to soak the substrate for 30 minutes. After drying the surface, sandblasting is used to remove the surface oxide scale and adhesives, so that the roughness after treatment is about 8.0.

[0045] Step 2: Preheat the workpiece to approximately 800℃.

[0046] Step 3: Using vacuum plasma spraying, Si powder with a particle size of 15-35 μm and HfO2 powder with a particle size of 0.05-1.5 μm are added to the hopper. The vacuum degree is 100 Pa, the current of the spraying equipment is 600 A, the powder feeding speed is 14 g / min, and the spraying distance is 150 mm to obtain the initial adhesive layer.

[0047] Step 4: The initial adhesive layer obtained in Step 3 is heat-treated at 1300℃ for 4 hours in a furnace with a controllable oxygen partial pressure atmosphere containing 0.1% oxygen to prepare an antioxidant, long-life environmental barrier coating adhesive layer with a thickness of 50μm.

[0048] Example 2

[0049] This invention provides an antioxidant, long-life environmental barrier coating adhesive layer. The adhesive layer is characterized by the following features: in the top surface layer, HfSiO4 particles are dispersed within SiO2; in the initial state adhesive layer at the bottom of the surface layer, nearly spherical HfO2 particles are discretely distributed in the Si matrix phase, forming a dense structure. The molar fraction of HfO2 is 15%, the particle size is 0.2 μm, and the aspect ratio of HfO2 is 1 to 2.

[0050] The process flow is as follows:

[0051] Step 1: The substrate surface to be prepared with Si-based adhesive layer is degreased and sandblasted. For degreasing, an organic solvent is used to soak the substrate for 35 minutes. After drying the surface, sandblasting is used to remove the oxide scale and adhesives on the surface, so that the roughness after treatment is about 9.0.

[0052] Step 2: Preheat the workpiece to approximately 900℃.

[0053] Step 3: Using vacuum plasma spraying, Si powder with a particle size of 15-35 μm and HfO2 powder with a particle size of 0.05-1.5 μm are added to the hopper. The vacuum degree is 110 Pa, the current of the spraying equipment is 610 A, the powder feeding speed is 16 g / min, and the spraying distance is 160 mm to obtain the initial adhesive layer.

[0054] Step 4: The initial adhesive layer obtained in Step 3 is heat-treated at 1310℃ for 5 hours in a furnace with a controllable oxygen partial pressure atmosphere containing 0.3% oxygen to prepare an antioxidant, long-life environmental barrier coating adhesive layer with a thickness of 100μm.

[0055] Example 3

[0056] This invention provides an antioxidant, long-life environmental barrier coating adhesive layer. The adhesive layer is characterized by the following features: in the top surface layer, HfSiO4 particles are dispersed within SiO2; in the initial state adhesive layer at the bottom of the surface layer, nearly spherical HfO2 particles are discretely distributed in the Si matrix phase, forming a dense structure. The molar fraction of HfO2 is 20%, the particle size is 0.6 μm, and the aspect ratio of HfO2 is 1 to 2.

[0057] The process flow is as follows:

[0058] Step 1: The substrate surface to be prepared with Si-based adhesive layer is degreased and sandblasted. For degreasing, an organic solvent is used to soak the substrate for 40 minutes. After drying the surface, sandblasting is used to remove the oxide scale and adhesives on the surface, so that the roughness after treatment is about 10.0.

[0059] Step 2: Preheat the workpiece to approximately 1000℃.

[0060] Step 3: Using vacuum plasma spraying, Si powder with a particle size of 15-35 μm and HfO2 powder with a particle size of 0.05-1.5 μm are added to the hopper. The vacuum degree is 120 Pa, the current of the spraying equipment is 620 A, the powder feeding speed is 18 g / min, and the spraying distance is 170 mm to obtain the initial adhesive layer.

[0061] Step 4: The initial adhesive layer obtained in Step 3 is heat-treated at 1320℃ for 6 hours in a furnace with a controllable oxygen partial pressure atmosphere containing 0.5% oxygen to prepare an antioxidant, long-life environmental barrier coating adhesive layer with a thickness of 180μm.

[0062] Example 4

[0063] The present invention provides an antioxidant, long-life environmental barrier coating adhesive layer. The adhesive layer is characterized in that: in the top surface layer, HfSiO4 particles are dispersedly distributed in SiO2; in the initial state adhesive layer at the bottom of the surface layer, nearly spherical HfO2 particles are discretely distributed in the Si matrix phase, forming a dense structure; the molar fraction of HfO2 is 30%; the particle size is 1 μm; and the aspect ratio of HfO2 is 1 to 2.

[0064] The process flow is as follows:

[0065] Step 1: The substrate surface to be prepared with Si-based adhesive layer is degreased and sandblasted. For degreasing, an organic solvent is used to soak the substrate for 45 minutes. After drying the surface, sandblasting is used to remove the surface oxide scale and adhesives, so that the roughness after treatment is about 11.0.

[0066] Step 2: Preheat the workpiece to approximately 1100℃.

[0067] Step 3: Using vacuum plasma spraying, Si powder with a particle size of 15-35 μm and HfO2 powder with a particle size of 0.05-1.5 μm are added to the hopper. The vacuum degree is 130 Pa, the current of the spraying equipment is 630 A, the powder feeding speed is 19 g / min, and the spraying distance is 175 mm to obtain the initial adhesive layer.

[0068] Step 4: The initial adhesive layer obtained in Step 3 is heat-treated at 1330℃ for 8 hours in a furnace with a controllable oxygen partial pressure atmosphere containing 0.7% oxygen to prepare an antioxidant, long-life environmental barrier coating adhesive layer with a thickness of 225μm.

[0069] Example 5

[0070] This invention provides an antioxidant, long-life environmental barrier coating adhesive layer. The adhesive layer is characterized by the following features: in the top surface layer, HfSiO4 particles are dispersed within SiO2; in the initial state adhesive layer at the bottom of the surface layer, nearly spherical HfO2 particles are discretely distributed in the Si matrix phase, forming a dense structure. The molar fraction of HfO2 is 35%, the particle size is 1.5 μm, and the aspect ratio of HfO2 is 1 to 2.

[0071] The process flow is as follows:

[0072] Step 1: The substrate surface to be prepared with Si-based adhesive layer is degreased and sandblasted. For degreasing, an organic solvent is used to soak the substrate for 50 minutes. After drying the surface, sandblasting is used to remove the oxide scale and adhesives on the surface, so that the roughness after treatment is about 12.0.

[0073] Step 2: Preheat the workpiece to approximately 1200℃.

[0074] Step 3: Using vacuum plasma spraying, Si powder with a particle size of 15-35 μm and HfO2 powder with a particle size of 0.05-1.5 μm are added to the hopper. The vacuum degree is 135 Pa, the current of the spraying equipment is 635 A, the powder feeding speed is 20 g / min, and the spraying distance is 180 mm to obtain the initial adhesive layer.

[0075] Step 4: The initial adhesive layer obtained in Step 3 is heat-treated at 1340℃ for 10h in a controlled oxygen partial pressure atmosphere furnace with 1% oxygen content to prepare an antioxidant, long-life environmental barrier coating adhesive layer with a thickness of 300μm.

[0076] The fracture toughness of the antioxidant and long-life environmental barrier coating adhesive blocks prepared in Examples 1 (Si10Hf), 3 (Si20Hf), and 4 (Si30Hf) was measured using nanoindentation method and compared with that of Comparative Example 1 (Si). The difference between Comparative Example 1 and Example 1 is that only Si powder was added to the hopper during vacuum plasma spraying.

[0077] Test results as follows Figure 2 As shown, by Figure 2 It can be seen that with the addition of HfO2, the discretely distributed HfO2 in the continuous and dense Si-based phase can improve the toughness of the coating.

[0078] The surface and cross-sectional morphology of the antioxidant and long-life environmental barrier coating adhesive blocks prepared in Examples 1 (Si10Hf), 3 (Si20Hf), and 4 (Si30Hf) after isothermal oxidation at 1370℃ for 10 h and 100 h are compared as follows: Figure 3 and Figure 4 As shown, by Figure 3 The surface morphology shows that after isothermal oxidation for different times, the sample surface is intact and no cracks appear; Figure 4 The cross-sectional morphology diagram shows that a SiO2-HfSiO4 composite layer appears in the upper surface layer, and this composite layer is relatively dense with no cracks.

[0079] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A method for preparing an antioxidant, long-life environmental barrier coating adhesive layer, characterized in that, An initial state adhesive layer was prepared on the substrate surface using vacuum plasma spraying technology. The initial state adhesive layer was then subjected to heat treatment in an oxygen partial pressure environment of 0.1%~1% to obtain an oxidation-resistant, long-life environmental barrier coating adhesive layer. The powder used in the vacuum plasma spraying is Si powder and HfO2 powder. The vacuum degree of the vacuum plasma spraying is 100~135 Pa, the current of the spraying equipment is 600~635 A, the powder feeding speed is 14~20 g / min, and the spraying distance is 150~180 mm. The heat treatment is vacuum heat treatment or inert atmosphere protection heat treatment. The anti-oxidation, long-life environmental barrier coating adhesive layer includes: an initial state adhesive layer of Si-doped HfO2 sequentially stacked on the substrate surface, and a surface layer of SiO2-doped HfSiO4. In the initial state adhesive layer, HfO2 particles are discretely distributed in Si. In the surface layer, HfSiO4 particles are diffusely distributed in SiO2.

2. The method for preparing an antioxidant, long-life environmental barrier coating adhesive layer according to claim 1, characterized in that, Before vacuum plasma spraying, the substrate surface is degreased, sandblasted, and preheated.

3. The antioxidant, long-life environmental barrier coating adhesive layer prepared by the preparation method according to claim 1 or 2.

4. The antioxidant, long-life environmental barrier coating adhesive layer according to claim 3, characterized in that, In the initial adhesive layer, the molar fraction of HfO2 is 10%~35%.

5. The antioxidant, long-life environmental barrier coating adhesive layer according to claim 3, characterized in that, In the initial adhesive layer, the particle size of HfO2 is 0.05~1.5 μm.

6. The antioxidant, long-life environmental barrier coating adhesive layer according to claim 3, characterized in that, In the initial adhesive layer, the aspect ratio of HfO2 is 1~2.

7. The antioxidant, long-life environmental barrier coating adhesive layer according to claim 3, characterized in that, The average thickness of the antioxidant, long-life environmental barrier coating adhesive layer is 50~300 μm.

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