Wide-speed-range plasma spraying two-component rare earth silicate environmental barrier coating and preparation method thereof

Abstract

The invention discloses a wide-speed-range plasma spraying two-component rare earth silicate environmental barrier coating and a preparation method, and belongs to the technical field of corrosion-resistant coatings, the method comprises the following steps: preparing a Si bonding layer on the surface of a SiC matrix by Si powder by adopting a wide-speed-range plasma spraying process; and rare earth silicate powder (Yb < 0.8 > Y < 0.2 >) 2Si2O7 or Yb < 2 > Si2O7 is sprayed on the surface of the Si bonding layer by adopting a wide-speed-range plasma spraying process, a (Yb < 0.8 > Y < 0.2 >) 2Si2O7 surface layer or a Yb < 2 > Si2O7 surface layer is prepared, and the two-component rare earth silicate environmental barrier coating is formed. The rare earth silicate ceramic environmental barrier coating with low porosity and high corrosion resistance is obtained at a high deposition rate through a wide-speed-range plasma spraying process, meanwhile, the rare earth silicate ceramic environmental barrier coating has the advantages of being low in cost, wide in applicability and the like, and the requirement of a next-generation ceramic-based turbine engine for the high-temperature service performance of the coating can be met.

Description

Technical Field

[0001] The invention belongs to the technical field of rare earth silicate ceramic-based environmental barrier coating preparation, and specifically relates to a wide-rate plasma spraying two-component rare earth silicate environmental barrier coating and a preparation method thereof. Background Art

[0002] SiC ceramic matrix composites are disruptive materials for the next generation of high-performance aviation gas turbine engines. However, water vapor released as a byproduct of the combustion of aviation kerosene and calcium-magnesium-aluminum-silicon oxide (CMAS) in the atmosphere will lead to a high decay rate of the workpiece in service. Environmental barrier coatings are currently the only effective surface protection method to protect SiC ceramic matrix composites from normal service in high-temperature corrosion environments, among which rare earth silicates are considered to be the most promising candidate materials for such corrosion-resistant coatings. At present, ytterbium pyrosilicate (Yb2Si2O7) is widely used in environmental barrier coating research, but the long-term use of this material in a high-temperature CMAS corrosion environment will cause serious damage to the environmental barrier coating structure.

[0003] In recent years, (Yb 0.8 Y 0.2 )2Si2O7 two-component silicate has high chemical stability and a thermal expansion coefficient that is closer to the CTE of the SiC / SiC matrix. Compared with the single-component Yb2Si2O7, it shows higher resistance to high-temperature CMAS corrosion. In addition, Y 3+ With a larger ionic radius and Ca in CMAS melt 2+ It has higher reactivity, which is conducive to the rapid reaction to form an apatite corrosion barrier. Mixing rare earth elements (Yb and Y) will produce a more complex lattice structure in pyrosilicate, which helps to improve the stability of the material in high temperature and corrosive environments. However, the rare earth silicate coatings reported so far have uneven composition, high porosity, and high crack defect structure, which hinders the ability of rare earth silicate coatings to form a dense apatite barrier layer at high temperatures. Summary of the invention

[0004] In view of the problems in the prior art that the composition of multi-component rare earth silicate environmental barrier coatings is uneven and the coating structure is easily destroyed in a high-temperature CMAS corrosion environment, the purpose of the present invention is to provide a wide-rate plasma sprayed two-component rare earth silicate environmental barrier coating and a preparation method. The coating prepared by this method has uniform composition distribution, high bonding strength, and is corrosion-resistant in a high-temperature CMAS corrosion environment.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A wide-range plasma spraying two-component rare earth silicate environmental barrier coating, the multi-component rare earth silicate environmental barrier coating comprises, from bottom to top, a SiC substrate, a Si bonding layer, (Yb 0.8 Y 0.2 )2Si2O7 surface layer or Yb2Si2O7 surface layer.

[0007] Furthermore, the thickness of the Si bonding layer is 80-100 μm.

[0008] Furthermore, (Yb 0.8 Y 0.2 )The thickness of the Yb2Si2O7 surface layer or the Yb2Si2O7 surface layer is 200-250 μm.

[0009] A method for preparing a wide-range plasma sprayed dual-component rare earth silicate environmental barrier coating comprises the following steps:

[0010] A Si bonding layer is prepared on the surface of the SiC substrate by using a wide-range plasma spraying process with Si powder;

[0011] Rare earth silicate powder (Yb 0.8 Y 0.2 )2Si2O7 or Yb2Si2O7 is sprayed on the surface of Si bonding layer by wide-range plasma spraying process to prepare (Yb 0.8 Y 0.2 )2Si2O7 surface layer or Yb2Si2O7 surface layer to form a two-component rare earth silicate environmental barrier coating.

[0012] Furthermore, the Si powder has a size of 10 to 30 μm.

[0013] Furthermore, the surface roughness of the SiC substrate is 3±1 μm, and the SiC substrate is an α-SiC substrate.

[0014] Furthermore, when Si powder is used to prepare a Si bonding layer on the surface of the SiC substrate using a wide-rate plasma spraying process, the parameters of the wide-rate plasma spraying process are as follows: spraying angle of 90°±5°, spraying distance of 170 mm, argon flow rate of 70±1 L / min, hydrogen flow rate of 10±1 L / min, voltage of 80±1 V, current of 500±5 A, and powder feeding amount of 20±2 g / min.

[0015] Furthermore, rare earth silicates (Yb 0.8 Y 0.2 )2Si2O7 or Yb2Si2O7 powder size is 10~50μm.

[0016] Furthermore, the rare earth silicate powder (Yb 0.8 Y 0.2When Yb2Si2O7 or Yb2Si2O7 is sprayed on the surface of the Si bonding layer by a wide-range plasma spraying process, the parameters of the wide-range plasma spraying process are as follows: spraying angle is 90°±5°, spraying distance is 120mm, argon flow rate is 70±1L / min, hydrogen flow rate is 8±1L / min, voltage is 78±1V, current is 500±5A, and powder feeding amount is 20±2g / min.

[0017] Furthermore, the thickness of the Si bonding layer is 80 to 100 μm; (Yb 0.8 Y 0.2 )The thickness of the Yb2Si2O7 surface layer or the Yb2Si2O7 surface layer is 200-250 μm.

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

[0019] The present invention introduces yttrium element into Yb2Si2O7 material to synthesize (Yb 0.8 Y 0.2 )2Si2O7 material, using the synergistic effect of the two-component rare earth silicate material, quickly realized the reaction between the coating surface and CMAS to form a dense and stable apatite barrier layer, further enhancing the (Yb 0.8 Y 0.2 The high temperature CMAS corrosion resistance of the 2Si2O7 coating is manifested in that the coating structure is not destroyed when kept at 1400℃ for 4h.

[0020] The present invention adopts wide-range plasma spraying technology to prepare SiC / Si / (Yb 0.8 Y 0.2 )2Si2O7 or Yb2Si2O7 multilayer system coating, effectively relieves the thermal stress of the coating, has the advantages of high deposition rate, simple process and low cost. The present invention utilizes the shock wave effect of ultra-high-speed plasma jet to refine the size of ceramic particles in the high-energy plasma jet, increase the momentum of the particles after impacting the substrate, and then increase the flatness of the flying particles, and finally realize the thinning of the coating structure. Further, the high collision pressure of fine particles causes the air film at the interface between the coating and the substrate to migrate quickly to the edge, thereby improving the bonding strength between the coating and the substrate and the cohesion of the coating, resulting in the porosity of the coating being reduced to less than 5%. Compared with the lamellar porous structure coating of conventional ordinary plasma spraying, the porosity is reduced by about 50%. Therefore, the coating prepared by wide-speed high-energy plasma spraying technology has the characteristics of high bonding strength and low porosity. The low-porosity dense structure coating can limit the penetration of CMAS melt along the coating defects, thereby further improving the anti-CMAS corrosion performance of the environmental barrier coating, and has good application prospects in the field of preparation of environmental barrier coatings.

[0021] Furthermore, the wide-speed range high-energy plasma spraying technology realizes high-voltage working mode and high energy density of the jet through the design of the spray gun structure, solves the problem of sticking of the traditional Laval nozzle under the condition of long-term internal powder feeding in supersonic plasma spraying, and can realize subsonic, transonic and supersonic plasma spraying under small gas flow conditions. The key process parameters of voltage 78V and current 500A can reduce the thickness of the coating tissue unit spread to a greater extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a scanning electron microscope (SEM) image of the Yb2Si2O7 surface layer after spraying in Example 1;

[0023] Figure 2 This is a SEM image of the Yb2Si2O7 surface layer after CMAS corrosion at 1400°C for 4 hours in Example 1;

[0024] Figure 3 This is the EDS spectrum of the front of the Yb2Si2O7 reaction layer after CMAS etching at 1400°C for 4 hours in Example 1; wherein (a) is the line scan area of ​​the energy spectrum; (b) is the distribution diagram of different elements;

[0025] Figure 4 For Example 2 (Yb 0.8 Y 0.2 )EDS spectrum of 2Si2O7 material. DETAILED DESCRIPTION

[0026] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are given in the drawings. However, the present invention can be implemented in a variety of different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thoroughly and comprehensively understood.

[0027] The wide-rate plasma spraying used in the present invention has the advantages of high deposition rate, strong coating adhesion, wide application range and low cost, and is expected to achieve an environmental barrier coating with low porosity and high CMAS corrosion resistance life.

[0028] In the present invention, by systematically regulating the spraying process, the coating structure including porosity and vertical crack density can be effectively controlled to meet the long-term service requirements of multi-component rare earth silicate environmental barrier coatings applied to the hot end components of the next generation of high thrust-to-weight ratio aircraft engines.

[0029] A method for preparing a wide-range plasma sprayed dual-component rare earth silicate environmental barrier coating of the present invention comprises the following steps:

[0030] (1) The SiC substrate to be sprayed is subjected to plasma sandblasting treatment to make its surface roughness (Ra) reach 3±1 μm; the SiC substrate is an α-SiC substrate.

[0031] (2) A Si bonding layer is prepared on the surface of the SiC substrate by using a wide-range plasma spraying process;

[0032] Among them, the Si powder used in the wide-rate plasma spraying process has a size of 10 to 30 μm and a crushed shape.

[0033] The parameters of the wide-range plasma spraying process for preparing a Si bonding layer on the surface of the SiC substrate are as follows: spraying angle is 90°±5°, spraying distance is 170 mm, argon flow rate is 70±1 L / min, hydrogen flow rate is 10±1 L / min, voltage is 80±1 V, current is 500±5 A, and powder feeding amount is 20±2 g / min.

[0034] The thickness of the Si bonding layer is 80 to 100 μm.

[0035] (3) Using wide-range plasma spraying technology to coat the dual-component (Yb 0.8 Y 0.2 )2Si2O7 or rare earth silicate powder Yb2Si2O7 is sprayed on the surface of Si bonding layer to prepare rare earth silicate (Yb 0.8 Y 0.2 )2Si2O7 surface layer or Yb2Si2O7 surface layer, forming a multi-component rare earth silicate environmental barrier coating, that is, Si / (Yb 0.8 Y 0.2 )2Si2O7 double layer environmental barrier coating or Si / Yb2Si2O 72 Si2O7 double-layer environmental barrier coating.

[0036] Among them, rare earth silicates (Yb 0.8 Y 0.2 )2Si2O7 or Yb2Si2O7 powder size is 10~50μm.

[0037] Preparation of rare earth silicate (Yb 0.8 Y 0.2 The parameters of the wide-range plasma spraying process for the Yb2Si2O7 or Yb2Si2O7 surface layer are as follows: spraying angle is 90°±5°, spraying distance is 120mm, argon flow rate is 70±1L / min, hydrogen flow rate is 8±1L / min, voltage is 78±1V, current is 500±5A, and powder feeding amount is 20±2g / min.

[0038] Rare earth silicates (Yb 0.8 Y 0.2)The thickness of the Yb2Si2O7 surface layer or the Yb2Si2O7 surface layer is 200-250 μm.

[0039] The following are specific embodiments.

[0040] Example 1

[0041] A method for preparing a wide-range plasma sprayed dual-component rare earth silicate environmental barrier coating comprises the following steps:

[0042] (1) A wide-range plasma spraying process is used to deposit a Si bonding layer with a thickness of 80 to 100 μm on a SiC substrate with a surface roughness of 3 μm after sandblasting.

[0043] (2) A wide-range plasma spraying process was used to prepare a Yb2Si2O7 surface layer on the surface of the Si bonding layer. The process parameters were as follows: spraying angle of 90°±5°, spraying distance of 120 mm, argon flow rate of 70±1 L / min, hydrogen flow rate of 8±1 L / min, voltage of 78±1 V, current of 500±5 A, and powder feeding rate of 20±2 g / min. The thickness of the Yb2Si2O7 surface layer was 200-250 μm.

[0044] See also Figure 1 It can be seen that the Yb2Si2O7 surface layer prepared by wide-rate plasma spraying process has low porosity (<5%) and no vertical cracks, and the coating has good density.

[0045] See also Figure 2 It can be seen that after CMAS corrosion at 1400℃ for 4h, the Yb2Si2O7 surface layer produced a corrosion reaction layer and was able to block the penetration of CMAS.

[0046] See also Figure 3 In (a) and (b), it can be seen that the X-ray energy spectrum (EDS) image of the front of the Yb2Si2O7 reaction layer after CMAS corrosion at 1400℃ for 4 hours further proves that the corrosion reaction layer of Yb2Si2O7 has good density and the ability to block the penetration of CMAS melt.

[0047] Example 2

[0048] A method for preparing a wide-range plasma sprayed dual-component rare earth silicate environmental barrier coating comprises the following steps:

[0049] (1) A wide-range plasma spraying process is used to deposit a Si bonding layer with a thickness of 80 to 100 μm on a SiC substrate with a surface roughness of 3±1 μm after sandblasting.

[0050] (2) Using wide-range plasma spraying technology to prepare (Yb0.8 Y 0.2 )2Si2O7 surface layer, the process parameters are as follows: spraying angle is 90°±5°, spraying distance is 120mm, argon flow rate is 70±1L / min, hydrogen flow rate is 8±1L / min, voltage is 78±1V, current is 500±5A, powder feeding amount is 20±2g / min. (Yb 0.8 Y 0.2 )The thickness of the 2Si2O7 surface layer is 200~250μm.

[0051] See also Figure 4 It can be seen that the two components (Yb 0.8 Y 0.2 )2Si2O7 silicate has uniform distribution of rare earth elements.

[0052] Example 3

[0053] A method for preparing a wide-range plasma sprayed multi-component rare earth silicate environmental barrier coating comprises the following steps:

[0054] (1) Si powder with a size of 10 to 30 μm was used to deposit a Si bonding layer with a thickness of 80 μm on a SiC substrate with a surface roughness of 2 μm after sandblasting by using a wide-range plasma spraying process.

[0055] (2) Yb2Si2O7 with a size of 10 to 50 μm was used to prepare a Yb2Si2O7 surface layer on the surface of the Si bonding layer by a wide-range plasma spraying process. The thickness of the Yb2Si2O7 surface layer was 200 μm. The process parameters were as follows: spraying angle of 90°±5°, spraying distance of 120 mm, argon flow rate of 70±1 L / min, hydrogen flow rate of 8±1 L / min, voltage of 78±1 V, current of 500±5 A, and powder feeding amount of 20±2 g / min, thereby obtaining a wide-range plasma sprayed two-component rare earth silicate environmental barrier coating.

[0056] Example 4

[0057] A method for preparing a wide-range plasma sprayed dual-component rare earth silicate environmental barrier coating comprises the following steps:

[0058] (1) Si powder with a size of 10 to 30 μm was used to deposit a Si bonding layer with a thickness of 100 μm on a SiC substrate with a surface roughness of 4 μm after sandblasting using a wide-range plasma spraying process.

[0059] (2) The size of 10 to 50 μm (Yb 0.8 Y 0.2 )2Si2O7 was prepared on the surface of Si bonding layer by wide-range plasma spraying process (Yb 0.8Y 0.2 )2Si2O7 surface layer, (Yb 0.8 Y 0.2 )2Si2O7 surface layer thickness is 250μm, the process parameters are as follows: spraying angle is 90°±5°, spraying distance is 120mm, argon flow rate is 70±1L / min, hydrogen flow rate is 8±1L / min, voltage is 78±1V, current is 500±5A, powder feeding amount is 20±2g / min, and a wide-range plasma sprayed two-component rare earth silicate environmental barrier coating is obtained.

[0060] Example 5

[0061] A method for preparing a wide-range plasma sprayed dual-component rare earth silicate environmental barrier coating comprises the following steps:

[0062] (1) Si powder with a size of 10 to 30 μm was deposited on a SiC substrate with a surface roughness of 2 μm after sandblasting using a wide-range plasma spraying process to form a Si bonding layer with a thickness of 90 μm.

[0063] (2) A wide-range plasma spraying process was used to prepare a Yb2Si2O7 surface layer on the surface of the Si bonding layer with a size of 10 to 50 μm. The thickness of the Yb2Si2O7 surface layer was 220 μm. The process parameters were as follows: spraying angle of 90°±5°, spraying distance of 120 mm, argon flow rate of 70±1 L / min, hydrogen flow rate of 8±1 L / min, voltage of 78±1 V, current of 500±5 A, and powder feeding amount of 20±2 g / min, thereby obtaining a wide-range plasma sprayed two-component rare earth silicate environmental barrier coating.

[0064] The above description is only for the best embodiment of the present invention, but it should not be understood as limiting the claims. The present invention is not limited to the above embodiments, and its specific structure is allowed to be changed. However, all changes made within the protection scope of the independent claims of the present invention are within the protection scope of the present invention.

[0065] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

Claims

1. A wide-range plasma sprayed dual-component rare earth silicate environmental barrier coating, characterized in that: The multi-component rare earth silicate environmental barrier coating comprises, from bottom to top, a SiC substrate, a Si bonding layer, (Yb 0.8 Y 0.2 )2Si2O7 surface layer or Yb2Si2O7 surface layer.

2. The wide-range plasma spraying two-component rare earth silicate environmental barrier coating according to claim 1, characterized in that: The thickness of the Si bonding layer is 80 to 100 μm.

3. The wide-range plasma spraying two-component rare earth silicate environmental barrier coating according to claim 1, characterized in that: (Yb 0.8 Y 0.2 )The thickness of the Yb2Si2O7 surface layer or the Yb2Si2O7 surface layer is 200-250 μm.

4. A method for preparing a wide-range plasma sprayed dual-component rare earth silicate environmental barrier coating, characterized in that: The following steps are involved: A Si bonding layer is prepared on the surface of the SiC substrate by using a wide-range plasma spraying process with Si powder; Rare earth silicate powder (Yb 0.8 Y 0.2 )2Si2O7 or Yb2Si2O7 is sprayed on the surface of Si bonding layer by wide-range plasma spraying process to prepare (Yb 0.8 Y 0.2 )2Si2O7 surface layer or Yb2Si2O7 surface layer to form a two-component rare earth silicate environmental barrier coating.

5. The method for preparing a wide-range plasma sprayed dual-component rare earth silicate environmental barrier coating according to claim 4, characterized in that: The Si powder size is 10 to 30 μm.

6. The method for preparing a wide-range plasma sprayed dual-component rare earth silicate environmental barrier coating according to claim 4, characterized in that: The surface roughness of the SiC substrate is 3±1 μm, and the SiC substrate is an α-SiC substrate.

7. The method for preparing a wide-range plasma sprayed dual-component rare earth silicate environmental barrier coating according to claim 4, characterized in that: When Si powder is used to prepare a Si bonding layer on the surface of the SiC substrate using a wide-range plasma spraying process, the parameters of the wide-range plasma spraying process are as follows: spraying angle is 90°±5°, spraying distance is 170mm, argon flow rate is 70±1L / min, hydrogen flow rate is 10±1L / min, voltage is 80±1V, current is 500±5A, and powder feeding amount is 20±2g / min.

8. The method for preparing a wide-range plasma sprayed dual-component rare earth silicate environmental barrier coating according to claim 4, characterized in that: Rare earth silicates (Yb 0.8 Y 0.2 )2Si2O7 or Yb2Si2O7 powder size is 10~50μm.

9. The method for preparing a wide-range plasma sprayed dual-component rare earth silicate environmental barrier coating according to claim 4, characterized in that: Rare earth silicate powder (Yb 0.8 Y 0.2 When Yb2Si2O7 or Yb2Si2O7 is sprayed on the surface of the Si bonding layer by a wide-range plasma spraying process, the parameters of the wide-range plasma spraying process are as follows: spraying angle is 90°±5°, spraying distance is 120mm, argon flow rate is 70±1L / min, hydrogen flow rate is 8±1L / min, voltage is 78±1V, current is 500±5A, and powder feeding amount is 20±2g / min.

10. The method for preparing a wide-range plasma sprayed dual-component rare earth silicate environmental barrier coating according to claim 4, characterized in that: The thickness of the Si bonding layer is 80 to 100 μm; (Yb 0.8 Y 0.2 )The thickness of the Yb2Si2O7 surface layer or the Yb2Si2O7 surface layer is 200-250 μm.

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