Preparation method and material of an adhesive layer for a long-life and crack-resistant environmental barrier coating

Abstract

The present invention discloses a preparation method and material for a long-life and crack-resistant environmental barrier coating adhesive layer. The environmental barrier adhesive layer has a three-phase structure, namely, large near-spherical HfO2 particles and small near-spherical Al2O3 particles are discretely distributed in the Si-based phase. The first dispersed phase of HfO2 particles can eliminate the oxide of Si and generate HfSiO4 with excellent resistance to water and oxygen corrosion. The second dispersed phase of Al2O3 can react with SiO2 to form mullite, increasing the fracture toughness of the oxide film. Compared with the traditional single Si adhesive layer, the second phase can react better with SiO2-TGO, eliminate the phase change stress caused by the generated TGO, and at the same time, the product has the characteristics of excellent oxygen barrier, water vapor barrier, and high fracture toughness, realizing the anti-cracking and long-life service of the environmental barrier coating adhesive layer.

Description

Technical Field

[0001] The present invention belongs to the technical field of coatings, and particularly relates to a preparation method and material for a long-life and anti-cracking environmental barrier coating bonding layer. Background Art

[0002] Environmental barrier coatings (EBCs) are a type of functional protective coating used on the surface of ceramic matrix composites (CMCs) in aeroengines or gas turbines to prevent the matrix from being corroded by water and oxygen. It can stably exist in an environment of high temperature, high flow rate, and high oxygen partial pressure to protect the matrix. The currently used environmental barrier coatings generally consist of a bonding layer, an intermediate layer, and a top layer. The bonding layer is generally pure Si.

[0003] During the actual service process of the environmental barrier coating, it is often affected by thermal cycling. At the same time, a layer of silicon oxide SiO2 is formed between the Si bonding layer and the intermediate layer, which is the thermally grown oxide. The existence of this oxide not only generates growth stress but also undergoes a phase change at 220 °C, resulting in volume change and generating phase change stress. At the same time, oxygen and water vapor infiltrating from the microcracks in the top layer will accelerate the oxidation of the bonding layer. The generation of phase change stress and growth stress often causes the environmental barrier coating to crack and spall, shortening the service life of the environmental barrier coating. Summary of the Invention

[0004] The present invention provides a preparation method and material for a long-life and anti-cracking environmental barrier coating bonding layer, which improves the internal stress problem caused by the generation and growth of thermally grown oxides on the Si bonding layer of the traditional environmental barrier coating, and at the same time solves the problem of excessive oxidation of the bonding layer by oxygen and water vapor infiltrating from the microcracks in the top layer.

[0005] To achieve the above object, a long-life and anti-cracking environmental barrier coating bonding layer material of the present invention is composed of three phases, namely HfO2, Si, and Al2O3. The HfO2 and Al2O3 are dispersed in the Si matrix phase. The molar fraction of HfO2 is 20% - 70%, the molar fraction of Si is 10% - 75%, and the molar fraction of Al2O3 is 5% - 20%.

[0006] Further, the first discrete phase HfO2 is in the shape of near-spherical particles with a size of 35 μm - 50 μm.

[0007] Further, the second discrete phase Al2O3 is in the shape of near-spherical particles with a size of 1 μm - 20 μm.

[0008] A preparation method for a long-life and anti-cracking environmental barrier coating bonding layer includes the following steps:

[0009] Step 1: Clean the substrate and then preheat it;

[0010] Step 2: Add the environmental barrier coating bonding layer material to the hopper and perform vacuum plasma spraying on the surface of the substrate to form a high melting point and long life environmental barrier coating bonding layer on the surface of the substrate.

[0011] The environmental barrier coating bonding layer material consists of three phases, namely HfO2, Si, and Al2O3. The HfO2 and Al2O3 are dispersed in the Si matrix phase; the molar fraction of HfO2 is 20% - 70%, the molar fraction of Si is 10% - 75%, and the molar fraction of Al2O3 is 5% - 20%.

[0012] Further, in Step 1, the cleaning of the substrate includes degreasing, descaling, and removing adhesives.

[0013] Further, in Step 1, degreasing is carried out by soaking in a 5 mol / L - 7 mol / L NaOH solution.

[0014] Further, in Step 1, sandblasting is used to remove the surface scale and adhesives.

[0015] Further, in Step 1, the preheating temperature is 850°C - 1200°C.

[0016] Further, in Step 2, spraying is carried out in an Ar and He gas environment.

[0017] Further, in Step 2, the flow rate of Ar gas is 42 L / min, the flow rate of He gas is 2 L / min, the powder feeding speed is 22 g / min, and the spraying distance is 205 mm.

[0018] Compared with the prior art, the present invention has at least the following beneficial technical effects:

[0019] The present invention provides a bonding layer material in which the second phase is two kinds. The first kind is HfO2, which reacts with SiO2 to form HfSiO4, thereby eliminating the phase change of SiO2. At the same time, HfSiO4 is generated, and HfSiO4 has excellent water and oxygen corrosion resistance and can block the water vapor and oxygen penetrating from the microcracks of the surface layer. The second kind is Al2O3, which reacts with SiO2 to form mullite, thereby eliminating the phase change of SiO2; and the thermal expansion coefficient of mullite (4 - 5×10 -6 K -1 ) is close to that of SiC (4.67×10 -6 K -1 ), and the fracture toughness (5.7 MPa·m 1 / 2 ) is much greater than that of SiO2 (0.7 MPa·m 1 / 2 ), thereby increasing the fracture toughness of the oxide film. The addition of the double discrete phase can effectively solve the problems of the growth of TGO and the excessive oxidation of the bonding layer, and improve the service life of the environmental barrier coating.

[0020] The preparation method described in the present invention uses the above-mentioned bonding layer material as a raw material and performs plasma spraying. The obtained bonding layer has two discretely distributed phases inside. The two discretely distributed phases can reduce the growth rate of TGO and inhibit its phase transformation at 220 °C, reduce internal stress, and extend the service life of the environmental barrier coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a Si-based environmental barrier bonding layer with long life and crack resistance. DETAILED DESCRIPTION OF THE INVENTION

[0022] In order to make the objectives and technical solutions of the present invention clearer and easier to understand, the present invention will be further described in detail below with reference to the drawings and embodiments. The specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0023] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be understood as a limitation of the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "plurality" is two or more. In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "mounted", "connected" and "connected" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal communication of two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0024] The present invention provides a long - life and crack - resistant environmental barrier coating bonding layer material. The environmental barrier bonding layer has a three - phase structure, that is, large near - spherical HfO2 particles and small near - spherical Al2O3 particles are discretely distributed in the Si - based phase. The first dispersed phase of HfO2 particles can eliminate the oxides of Si and generate HfSiO4 with excellent water and oxygen corrosion resistance. The second dispersed phase of Al2O3 can react with SiO2 to form mullite, increasing the fracture toughness of the oxide film. Compared with the traditional single - Si bonding layer, the second phase can react well with SiO2 - TGO, eliminate the phase - change stress brought by the generated TGO, and at the same time, the product has the characteristics of excellent oxygen barrier, water vapor barrier, and high fracture toughness, realizing the anti - cracking and long - life service of the environmental barrier coating bonding layer.

[0025] Example 1

[0026] Referring to Figure 1 , the present invention provides a composition design for a long - life and crack - resistant environmental barrier coating bonding layer material. The characteristics of this bonding layer are that granular dispersed phases are dispersed in the Si - based phase. The dispersed phases include HfO2 and Al2O3. The molar fraction of HfO2 is 20%, the molar fraction of Al2O3 is 5%, and the molar fraction of Si is 75%. The particle size of HfO2 is 35μm, and the particle size of Al2O3 is 1μm.

[0027] The preparation process flow of a long - life and crack - resistant environmental barrier coating bonding layer is as follows:

[0028] Step 1: Treat the surface of the substrate to be prepared for the Si - based bonding layer to remove oil, scale, and adhesives. For degreasing, soak it in a 5mol / L NaOH solution for 30min, then dry the surface of the substrate, and use sandblasting to remove the surface scale and adhesives, so that the surface roughness of the treated substrate is about 10.0.

[0029] Step 2: Pre - heat the substrate, and the pre - heating temperature is 850°C.

[0030] Step 3: Use vacuum plasma spraying to put the powder of the long - life and crack - resistant environmental barrier coating bonding layer material into the feed bin and spray it on the surface of the substrate in an Ar and He gas environment. The flow rate of Ar gas is 42L / min, the flow rate of He gas is 2L / min, the arc voltage of the spraying equipment is 42V, the current is 610A, the powder feeding speed is 22g / min, and the spraying distance is 205mm, obtaining a coating thickness of 75μm.

[0031] This coating is a long - life and crack - resistant environmental barrier coating bonding layer.

[0032] Example 2

[0033] An embodiment of the present invention provides a composition design of a bonding layer material for a long - life and crack - resistant environmental barrier coating. The characteristics of this bonding layer are as follows: granular slow - release stabilizer particles HfO₂ and Al₂O₃ are discretely dispersed in the Si - based phase. The overall bonding layer has a dense structure. The molar fraction of HfO₂ is 32%, the molar fraction of Al₂O₃ is 8%, and the molar fraction of Si is 60%. The particle size of HfO₂ is 38 μm, and the particle size of Al₂O₃ is 3 μm.

[0034] At the same time, the preparation process flow of the bonding layer is given as follows:

[0035] Step 1: Treat the surface of the substrate to be prepared with the Si - based bonding layer to remove oil, scale, and adhesions. For oil removal, soak it in a 5.5 mol / L NaOH solution for 35 min, then dry the surface, and use sandblasting to remove the surface scale and adhesions, so that the roughness after treatment is about 9.5.

[0036] Step 2: Perform a pre - heating treatment on the substrate, and the pre - heating temperature is 950 °C.

[0037] Step 3: Use vacuum plasma spraying. Add the powder of the bonding layer material for the long - life and crack - resistant environmental barrier coating to the hopper, and spray it on the surface of the substrate in an Ar and He gas environment. The flow rate of Ar gas is 45 L / min, the flow rate of He gas is 2.5 L / min, the arc voltage of the spraying equipment is 45 V, the current is 620 A, the powder feeding speed is 25 g / min, and the spraying distance is 215 mm. The obtained coating thickness is 85 μm.

[0038] This coating is a bonding layer for a long - life and crack - resistant environmental barrier coating.

[0039] Example 3

[0040] An embodiment of the present invention provides a composition design of a bonding layer material for a long - life and crack - resistant environmental barrier coating. The characteristics of this bonding layer are as follows: granular slow - release stabilizer particles are discretely dispersed in the Si - based phase. The overall structure is dense. The molar fraction of HfO₂ is 40%, the molar fraction of Al₂O₃ is 10%, and the molar fraction of Si is 50%. The particle size of HfO₂ is 45 μm, and the particle size of Al₂O₃ is 9 μm.

[0041] At the same time, the preparation process flow of the bonding layer is given as follows:

[0042] Step 1: Treat the surface of the substrate to be prepared with the Si - based bonding layer to remove oil, scale, and adhesions. For oil removal, soak it in a 6 mol / L NaOH solution for 40 min, then dry the surface, and use sandblasting to remove the surface scale and adhesions, so that the roughness after treatment is about 9.

[0043] Step 2: Perform a pre - heating treatment on the substrate, and the pre - heating temperature is 1050 °C.

[0044] Step 3: Using vacuum plasma spraying, add the powder of the long-life and anti-cracking environmental barrier coating adhesive layer material to the hopper, and spray it on the surface of the substrate in an Ar and He gas environment. The flow rate of Ar gas is 48 L / min, the flow rate of He gas is 3 L / min, the arc voltage of the spraying equipment is 48 V, the current is 630 A, the powder feeding speed is 28 g / min, and the spraying distance is 225 mm. The obtained coating thickness is 95 μm. This coating is a long-life and anti-cracking environmental barrier coating adhesive layer.

[0045] Example 4

[0046] The embodiment of the present invention provides a composition design of a long-life and anti-cracking environmental barrier coating adhesive layer. The characteristics of this adhesive layer are that granular slow-release stabilizer particles are discretely dispersed in the Si matrix phase, and the overall structure is dense. The molar fraction of HfO2 is 55%, the molar fraction of Al2O3 is 15%, and the molar fraction of Si is 30%. The particle size of HfO2 is 48 μm, and the particle size of Al2O3 is 15 μm.

[0047] At the same time, the preparation process flow of the adhesive layer is given as follows:

[0048] Step 1: Treat the surface of the substrate to be prepared with the Si-based adhesive layer to remove oil, scale, and adhesives. Select a 6.5 mol / L NaOH solution to soak for 45 min for degreasing, then dry the surface, and use sandblasting to remove the surface scale and adhesives, so that the roughness after treatment is about 8.5;

[0049] Step 2: Preheat the substrate, and the preheating temperature is 1100 °C;

[0050] Step 3: Using vacuum plasma spraying, add the powder of the long-life and anti-cracking environmental barrier coating adhesive layer material to the hopper, and spray it on the surface of the substrate in an Ar and He gas environment. The flow rate of Ar gas is 50 L / min, the flow rate of He gas is 3.5 L / min, the arc voltage of the spraying equipment is 50 V, the current is 640 A, the powder feeding speed is 30 g / min, and the spraying distance is 235 mm. The obtained coating thickness is 110 μm. This coating is a long-life and anti-cracking environmental barrier coating adhesive layer.

[0051] Example 5

[0052] The embodiment of the present invention provides a composition design of a long-life and anti-cracking environmental barrier coating adhesive layer. The characteristics of this adhesive layer are that granular slow-release stabilizer particles are discretely dispersed in the Si matrix phase, and the overall structure is dense. The molar fraction of HfO2 is 70%, the molar fraction of Al2O3 is 20%, and the molar fraction of Si is 10%. The particle size of HfO2 is 50 μm, and the particle size of Al2O3 is 20 μm.

[0053] The preparation process flow of the bonding layer is given as follows:

[0054] Step 1: Treat the surface of the substrate for preparing the Si-based bonding layer to remove oil, oxide scale, and adhesives. For oil removal, soak it in a 7 mol / L NaOH solution for 50 min, then dry the surface and use sandblasting to remove the surface oxide scale and adhesives, so that the roughness after treatment is about 8;

[0055] Step 2: Preheat the substrate, and the preheating temperature is 1200 °C;

[0056] Step 3: Use vacuum plasma spraying. Add the powder of the long-life and crack-resistant environmental barrier coating bonding layer material to the hopper, and spray it on the surface of the substrate in an Ar and He gas environment. The flow rate of Ar gas is 55 L / min, the flow rate of He gas is 3.8 L / min, the arc voltage of the spraying equipment is 55 V, the current is 650 A, the powder feeding speed is 35 g / min, and the spraying distance is 250 mm. The thickness of the obtained coating is 125 μm. This coating is a long-life and crack-resistant environmental barrier coating bonding layer.

[0057] The above content is only to illustrate the technical idea of the present invention and cannot be used to limit the protection scope of the present invention. Any modification made on the basis of the technical solution according to the technical idea proposed by the present invention falls within the protection scope of the claims of the present invention.

Claims

1. A long-life and crack-resistant environmental barrier coating adhesive layer material, characterized in that, The bonding layer material consists of three phases, namely HfO2, Si, and Al2O3. HfO2 and Al2O3 are dispersed in the Si matrix phase. The mole fraction of HfO2 is 20% - 70%, the mole fraction of Si is 10% - 75%, and the mole fraction of Al2O3 is 5% - 20%. The first discrete phase HfO2 is in the shape of near-spherical particles, and the second discrete phase Al2O3 is also in the shape of near-spherical particles. The size of the first discrete phase HfO2 is 35μm - 50μm, and the size of the second discrete phase Al2O3 is 1μm - 20μm.

2. A preparation method for an adhesive layer of a long-life and crack-resistant environmental barrier coating, characterized in that, It includes the following steps: Step 1: Clean the substrate and then preheat it. Step 2: Add the environmental barrier coating bonding layer material described in Claim 1 to the hopper, and perform vacuum plasma spraying on the surface of the substrate to form an environmental barrier coating bonding layer with high melting point and long service life on the surface of the substrate.

3. The preparation method of a long-life and crack-resistant environmental barrier coating adhesive layer according to claim 2, characterized in that, In Step 1, the cleaning of the substrate includes degreasing, removing oxide scale, and removing adhesives.

4. The preparation method of a long-life and crack-resistant environmental barrier coating adhesive layer according to claim 3, characterized in that, In Step 1, the degreasing is carried out by immersing in a 5mol / L - 7mol / L NaOH solution.

5. The preparation method of a long-life and crack-resistant environmental barrier coating adhesive layer according to claim 3, characterized in that, In Step 1, sandblasting is used to remove the surface oxide scale and adhesives.

6. The preparation method of a long-life and crack-resistant environmental barrier coating adhesive layer according to claim 2, characterized in that, In Step 1, the preheating temperature is 850℃ - 1200℃.

7. The preparation method of a long-life and crack-resistant environmental barrier coating adhesive layer according to claim 2, characterized in that, In Step 2, the spraying is carried out in an Ar and He gas environment.

8. A method for preparing a long-life and crack-resistant environmental barrier coating adhesive layer according to claim 7, characterized in that In Step 2, the flow rate of Ar gas is 42L / min, the flow rate of He gas is 2L / min, the powder feeding speed is 22g / min, and the spraying distance is 205mm.

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