A thermal / environmental barrier coating resistant to thermal shock and heat shock and its preparation method

Abstract

The present invention relates to a thermal / environmental barrier coating resistant to thermal shock and heat shock and a preparation method thereof. The thermal / environmental barrier coating comprises a Si bonding layer, a Yb2Si2O7 environmental barrier layer, a β-LiAlSiO4-(RE1 x RE2 1‑x )2Zr2O7 transition layer and (RE1 x RE2 1‑x )2Zr2O7 thermal barrier layer, or a Si bonding layer, a Yb2Si2O7 environmental barrier layer and a β-LiAlSiO4-(RE1 x RE2 1‑x )2Zr2O7 thermal barrier coating, where 0≤x≤1, and RE1 and RE2 are one of Gd, La, Nd, Yb, Dy, Sc, and Sm. The thermal / environmental barrier coating of the present invention has a thermal expansion coefficient that exhibits a gradual, gradual increase in each layer's material, resulting in high thermal compatibility with the ceramic-based composite material, long thermal shock life, and excellent thermal shock resistance.

Description

Technical Field

[0001] The present invention belongs to the field of integrated thermal barrier / environmental barrier coatings, and in particular relates to a thermal / environmental barrier coating having excellent thermal shock resistance and thermal shock resistance and a preparation method thereof. Background Art

[0002] Compared to high-temperature alloys, ceramic-based composites (CMCs) offer advantages such as low density, high-temperature resistance, and high specific strength, making them ideal materials for the hot-end components of high-performance aerospace engines. They have been successfully applied to key components such as turbine outer rings, combustion chamber liner, tail nozzle, and guide vanes. In the combustion chamber environment, CMCs experience a rapid degradation in performance due to the combined effects of thermal, mechanical, and chemical factors, including high-temperature water and oxygen, molten salt corrosion, and foreign particle erosion. Therefore, environmental barrier coatings must be applied to their surfaces to extend their service life.

[0003] As aircraft engines continue to pursue higher thrust-to-weight ratios and higher thermal efficiency, turbine inlet temperatures continue to rise. Currently, third-generation environmental barrier coating systems using rare earth silicates as surface materials can operate stably and for extended periods below 1350°C. However, at higher temperatures, their high thermal conductivity causes the SiC fibers in the composite material to exceed their temperature tolerance, leading to fiber performance degradation and a significant reduction in the composite's service life. Consequently, this system no longer meets the design requirements of the next generation of high-performance engines.

[0004] Preparing a thermal insulation surface layer with a high melting point, low thermal conductivity, and high-temperature phase stability on the surface of the environmental barrier coating is an important way to increase the service temperature of the environmental barrier coating. However, the mismatch of the thermal expansion coefficient between the thermal barrier surface layer and the rare earth silicate and CMC substrates is still the main reason for the thermal stress and cracking of the coating, which leads to interface oxidation and peeling. At present, researchers mainly add a buffer layer to form a multi-layer gradient structure to alleviate the thermal adaptability between the layers of the thermal / environmental barrier coating system. This method reduces the cyclic stress inside the coating to a certain extent, but during long-term service, the interface chemical stability between the layers in the coating and between the coating and the substrate will inevitably decrease, which will lead to cracking or even failure of the coating. In addition, the design of the multi-layer structure increases the complexity of the T / EBC preparation process and significantly increases the manufacturing cost.

[0005] Therefore, there is an urgent need to develop a new type of thermal / environmental barrier coating with high thermal insulation, long life, and thermal adaptability to the substrate, and its preparation method, so as to improve the service temperature and service life of the hot end components of aircraft engines. Summary of the Invention

[0006] In view of the above-mentioned situation of the prior art, the purpose of the present invention is to provide a thermal / environmental barrier coating and its preparation method having good thermal insulation effect, high thermal adaptability with the substrate, long thermal shock resistance life and excellent thermal shock resistance at 1400°C, so that the coating can effectively extend the service life of ceramic-based composite materials at this temperature, thereby improving the service reliability of hot end components in aircraft engines.

[0007] To achieve the above object, the present invention provides a thermal / environmental barrier coating that is resistant to thermal shock and thermal shock. When the coating has a four-layer structure, it includes, from the inside to the outside, a Si bonding layer, a Yb2Si2O7 environmental barrier layer, a β-LiAlSiO4-(RE1 x RE2 1-x )2Zr2O7 transition layer and (RE1 x RE2 1-x )2Zr2O7 thermal barrier layer, wherein (0≤x≤1); when the coating is a three-layer structure, it includes, from the inside to the outside, a Si bonding layer, a Yb2Si2O7 environmental barrier layer, a β-LiAlSiO4-(RE1 x RE2 1-x )2Zr2O7 thermal barrier layer, where (0≤x≤1);

[0008] When the coating is a four-layer structure, the β-LiAlSiO4 and (RE1 x RE2 1-x )2Zr2O7 weight ratio is 1:6 to 3:7;

[0009] When the coating is a three-layer structure, the β-LiAlSiO4 and (RE1 x RE2 1-x )2Zr2O7 weight ratio is 1:5 to 2:3;

[0010] The RE1 and RE2 are one of Gd, La, Nd, Yb, Dy, Sc and Sm.

[0011] Preferably, when the coating has a four-layer structure, the thickness of the Si bonding layer is 50 to 100 μm, the thickness of the Yb2Si2O7 environmental barrier layer is 80 to 120 μm, and the thickness of the β-LiAlSiO4-(RE1 x RE2 1-x )2Zr2O7 transition layer thickness is 80~120μm, said (RE1 x RE2 1-x )2Zr2O7 thermal barrier layer thickness is 80~120μm.

[0012] Preferably, when the coating is a three-layer structure, the thickness of the Si bonding layer is 50 to 100 μm, the thickness of the Yb2Si2O7 environmental barrier layer is 120 to 180 μm, and the thickness of the β-LiAlSiO4-(RE1 x RE2 1-x )The thickness of the 2Zr2O7 thermal barrier surface layer is 120~180μm.

[0013] Preferably, the transition layer contains β-LiAlSiO4 and (RE1 x RE2 1-x )The weight ratio of 2Zr2O7 is 1:5~2:5.

[0014] Preferably, the β-LiAlSiO4 and (RE1 x RE2 1-x )The weight ratio of 2Zr2O7 is 1:4~1:3.

[0015] On the other hand, a method for preparing the thermal / environmental barrier coating resistant to thermal shock and heat shock as described above is provided, the method comprising the following steps:

[0016] S1: Si bonding layer prepared by low-pressure plasma spraying process;

[0017] S101. Preferably, the ceramic-based composite material is sandblasted before spraying, with the sandblasting sand particles being 100-200 mesh quartz sand, the sandblasting pressure being 1-3 bar, and the sandblasting time being 10-30 seconds; further, the composite material substrate is heated by a plasma flame flow to a surface temperature of 500-800° C.;

[0018] S102. Preferably, argon and hydrogen are used as plasma, the flow rate of argon is 30-80 L / min, the flow rate of hydrogen is 6-15 L / min, the spraying distance is 250-500 mm, the spraying current is 400-800 A, the powder feeding rate is 10-30%, the vacuum chamber pressure is 50-500 Pa, and the Si powder particle size is 10-60 μm.

[0019] S2: Atmospheric plasma spraying technology is used to prepare Yb2Si2O7 environmental barrier layer, β-LiAlSiO4-(RE1 x RE2 1-x )2Zr2O7 transition layer and (RE1 x RE2 1-x )2Zr2O7 thermal barrier coating;

[0020] S201. Preferably, in the process of preparing the environmental barrier layer, argon and hydrogen are used as plasma, the flow rate of argon is 40-60L / min, the flow rate of hydrogen is 6-15L / min, the spraying distance is 100-150mm, the spraying current is 600-1000A, the powder feeding rate is 5-25%, and the Yb2Si2O7 powder particle size is 15-80μm.

[0021] S202. Preferably, in the process of preparing the transition layer, argon and hydrogen are used as plasma, the flow rate of argon is 40-70 L / min, the flow rate of hydrogen is 4-16 L / min, the spraying distance is 80-150 mm, the spraying current is 500-1000 A, the powder feeding rate is 10-30%, and the β-LiAlSiO4-(RE1 x RE2 1-x )2Zr2O7 powder particle size is 5-50μm.

[0022] S203. Preferably, in the process of preparing the thermal barrier surface layer, argon and hydrogen are used as plasma, the flow rate of argon is 40-70 L / min, the flow rate of hydrogen is 4-16 L / min, the spraying distance is 80-150 mm, the spraying current is 500-1000 A, the powder feeding rate is 10-30%, (RE1 x RE2 1-x )2Zr2O7 powder particle size is 5-50μm.

[0023] S3: Vacuum heat treatment of ceramic matrix composites with thermal / environmental barrier coatings.

[0024] Preferably, the vacuum heat treatment parameters are: heat treatment temperature of 1000-1200°C, time of 4-6 hours, vacuum degree of 10 -3 Pa, that is, as long as the vacuum degree reaches 10 -3 Pa level is sufficient.

[0025] The coating prepared by the present invention has excellent thermal shock resistance and thermal shock resistance. Under the conditions of 1400°C, flame flow velocity of 0.5 Mach, constant temperature for 120 seconds, and air cooling for 30 seconds, the thermal shock life is not less than 500 times; under the conditions of 1400°C, heat preservation for 5 minutes, and air cooling for 5 minutes, the thermal shock life is not less than 500 times. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The drawings of the present invention are provided for illustrative purposes only, and the proportions and sizes of the layers in the drawings may not necessarily be consistent with the actual product.

[0027] Figure 1 is a schematic cross-sectional structure diagram of a four-layer thermal / environmental barrier coating prepared on the surface of a ceramic matrix composite material according to one embodiment of the present invention;

[0028] Figure 2 is a schematic cross-sectional view of a three-layer thermal / environmental barrier coating prepared on the surface of a ceramic matrix composite material according to another embodiment of the present invention;

[0029] Figure 3 is a flow chart of a method for preparing a four-layer thermal / environmental barrier coating on a surface of a ceramic matrix composite material according to an embodiment of the present invention;

[0030] Figure 4 In one embodiment of the present invention, β-LiAlSiO4-4(Gd 0.9 Yb 0.1 )Microstructure of 2Zr2O7 ceramic powder;

[0031] Figure 5 The figure shows the surface morphology of the three-layer thermal / environmental barrier coating according to the present invention. DETAILED DESCRIPTION

[0032] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0033] The features of various aspects of the embodiments of the present invention will be described in detail below. In the detailed description below, many specific details are provided to provide a comprehensive understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention can also be implemented without these specific details. The following description of the embodiments is merely intended to provide a better understanding of the present invention by illustrating examples of the present invention. The present invention is not limited to any specific settings and methods provided below, but rather covers all product structures, any improvements, replacements, etc. of the methods covered without departing from the spirit of the present invention. In the various drawings and the following description, well-known structures and technologies are not shown to avoid unnecessary ambiguity in the present invention.

[0034] Figure 1 The cross-sectional structure diagram of a four-layer thermal / environmental barrier coating prepared on the surface of a ceramic matrix composite material according to an embodiment of the present invention is shown in the figure. As shown in the figure, the thermal / environmental barrier coating includes, from the ceramic matrix composite material substrate 1 outward, a Si bonding layer 2, a Yb2Si2O7 environmental barrier layer 3, a β-LiAlSiO4-(RE1 x RE2 1-x )2Zr2O7 transition layer 4, (RE1 x RE21-x )2Zr2O7 thermal barrier surface layer 5.

[0035] The β-LiAlSiO4-(RE1 x RE2 1-x )2Zr2O7 transition layer and (RE1 x RE2 1-x )2Zr2O7 thermal barrier layer, RE1 and RE2 are one of Gd, La, Nd, Yb, Dy, Sc and Sm. The transition layer β-LiAlSiO4 and (RE1 x RE2 1-x The weight ratio of β-LiAlSiO4 and (RE1 x RE2 1-x When the weight ratio of )2Zr2O7 is used in accordance with the above composition, the obtained transition layer has a thermal expansion coefficient that matches the substrate, the environmental barrier layer and the thermal barrier surface layer.

[0036] Figure 2 The cross-sectional structure diagram of a three-layer thermal / environmental barrier coating prepared on the surface of a ceramic matrix composite material according to another embodiment of the present invention. The thermal / environmental barrier coating comprises, from the ceramic matrix composite material substrate 1 outward, a Si bonding layer 2, a Yb2Si2O7 environmental barrier layer 3, a β-LiAlSiO4-(RE1 x RE2 1-x )2Zr2O7 thermal barrier surface layer 5'.

[0037] The β-LiAlSiO4-(RE1 x RE2 1-x )2Zr2O7 thermal barrier layer, RE1 and RE2 are one of Gd, La, Nd, Yb, Dy, Sc and Sm. The β-LiAlSiO4 and (RE1) x RE2 1-x The weight ratio of β-LiAlSiO4 and (RE1 x RE2 1-x When the weight ratio of )2Zr2O7 is used in accordance with the above composition, the obtained thermal barrier surface layer has a low thermal conductivity and a thermal expansion coefficient adapted to the substrate and the environmental barrier layer, and has no phase change at room temperature of -1650°C.

[0038] Figure 3 The present invention is a flowchart of a method for preparing a four-layer thermal / environmental barrier coating on the surface of a ceramic matrix composite material according to an embodiment of the present invention.

[0039] The method comprises the following steps:

[0040] S1: Si bonding layer prepared by low-pressure plasma spraying process;

[0041] S101. To increase the surface roughness of the ceramic-based composite material and thereby enhance the bonding strength between the bonding layer and the substrate, the ceramic-based composite material is sandblasted before spraying, with the sandblasting grit being 100-200 mesh quartz sand, the sandblasting pressure being 1-3 bar, and the sandblasting time being 10-30 seconds; further, the composite material substrate is heated using a plasma flame flow to a surface temperature of 500-800° C.;

[0042] The particle size of S102 and Si powder is 10-60μm, argon and hydrogen are used as plasma, the flow rate of argon is 30-80L / min, the flow rate of hydrogen is 6-15L / min, the spraying distance is 250-500mm, the spraying current is 400-800A, the powder feeding rate is 10-30%, and the vacuum chamber pressure is 50-500Pa.

[0043] S2: Atmospheric plasma spraying technology is used to prepare Yb2Si2O7 environmental barrier layer, β-LiAlSiO4-(RE1 x RE2 1-x )2Zr2O7 transition layer and (RE1 x RE2 1-x )2Zr2O7 thermal barrier coating;

[0044] The particle size of S201 and Yb2Si2O7 powders is 15-80μm; argon and hydrogen are used as plasma, the flow rate of argon is 40-60L / min, the flow rate of hydrogen is 6-15L / min, the spraying distance is 100-150mm, the spraying current is 600-1000A, and the powder feeding rate is 5-25%.

[0045] S202、β-LiAlSiO4-(RE1 x RE2 1-x )2Zr2O7 powder particle size is 5-50μm, and the powder morphology is porous spherical micron powder, which is beneficial to improving deposition efficiency and coating tissue uniformity; argon and hydrogen are used as plasma, the argon flow rate is 40-70L / min, the hydrogen flow rate is 4-16L / min, the spraying distance is 80-150mm, the spraying current is 500-1000A, and the powder feeding rate is 10-30%.

[0046] S203, (RE1 x RE2 1-x)2Zr2O7 powder particle size is 5-50μm, and the powder morphology is hollow spherical micron powder, which is beneficial to improving deposition efficiency and coating uniformity; argon and hydrogen are used as plasma, the argon flow rate is 40-70L / min, the hydrogen flow rate is 4-16L / min, the spraying distance is 80-150mm, the spraying current is 500-1000A, and the powder feeding rate is 10-30%.

[0047] S3: Vacuum heat treatment of ceramic matrix composites with thermal / environmental barrier coatings.

[0048] Heat treatment temperature is 1000-1200℃, time is 4-6h, vacuum degree is ~10 -3 Pa.

[0049] Although the above description only describes the method for preparing a four-layer structure thermal / environmental barrier coating on the surface of a ceramic matrix composite material of the present invention, it is obvious that the above method is also applicable to preparing a three-layer structure thermal / environmental barrier coating on the surface of a ceramic matrix composite material of the present invention, that is, omitting step S203 and preparing β-LiAlSiO4-(RE1 x RE2 1-x )2Zr2O7 layer can be used as thermal barrier surface layer.

[0050] Example 1

[0051] (1) Prepare SiC f The SiC / SiC ceramic composite matrix specimen, with a size of φ25 mm × 3 mm, was ultrasonically cleaned with acetone for 20 min and then dried.

[0052] (2) The ceramic matrix composite material was sandblasted before spraying. The sandblasting sand particles were 150 mesh quartz sand, the sandblasting pressure was 2 bar, and the sandblasting time was 20 s.

[0053] (3) The particle size of the Si powder after spray granulation is selected to be 15-45 μm, the particle size of the Yb2Si2O7 powder is 15-80 μm, and the particle size of the β-LiAlSiO4-4(Gd 0.9 Yb 0.1 )2Zr2O7 powder particle size is 5-50μm (such as Figure 4 shown), (Gd 0.9 Yb 0.1 The particle size of 2Zr2O7 powder is 5-50μm. The powder morphology after granulation is porous spherical powder.

[0054] The Si, Yb2Si2O7, β-LiAlSiO4 and other powders used in the present invention can be obtained from the market, and their preparation processes are also well known to those skilled in the art. For example, in this embodiment, Si and Yb2Si2O7 powders were purchased from Hunan Zhaoyi Thermal Spraying Materials Co., Ltd., and β-LiAlSiO4 powder was purchased from Changsha College. In addition, although the following example illustrates β-LiAlSiO4-4(Gd 0.9 Yb 0.1 )2Zr2O7 powder and (Gd 0.9 Yb 0.1 )2Zr2O7 powder preparation method, but such a preparation method is also known to those skilled in the art, so that the raw material powder is used to prepare the required composition (RE1) by a similar preparation method. x RE2 1-x )2Zr2O7 powder and β-LiAlSiO4-(RE1 x RE2 1-x )2Zr2O7 powder is within the capabilities of those skilled in the art.

[0055] β-LiAlSiO4-4(Gd 0.9 Yb 0.1 )2Zr2O7 powder is prepared by:

[0056] (a) Gd2O3, Yb2O3, and ZrO2 were mixed in a molar ratio of 0.9:0.1:1 and then wet-milled for 6 h at a speed of 400 r / min. -1 The milled slurry was dried in a drying oven at 75°C for 5 hours, manually ground, and passed through a 200-mesh sieve. The resulting powder was sintered at 1500°C for 5 hours.

[0057] (b) β-LiAlSiO4 powder and (Gd 0.9 Yb 0.1 )2Zr2O7 powder was mixed in a weight ratio of 1:4 and then wet-milled for 4 h at a speed of 200 r / min. -1 , Place the ball-milled slurry in a drying oven at 75℃ and dry for 5h;

[0058] (c) The dried powder was spray granulated with the following parameters: inlet temperature of 200°C, outlet temperature of 100°C, and PVA as the binder; the spray granulated powder was sintered at 1200°C for 4 hours to remove the organic binder layer.

[0059] (Gd 0.9 Yb 0.1 )2Zr2O7 powder is prepared by:

[0060] (a) Gd2O3, Yb2O3, and ZrO2 were mixed in a molar ratio of 0.9:0.1:1 and then wet-milled for 6 h at a speed of 400 r / min. -1 The milled slurry was dried in a drying oven at 75°C for 5 hours, manually ground, and passed through a 200-mesh sieve. The resulting powder was sintered at 1500°C for 5 hours.

[0061] (b) The dried powder was spray granulated with the following parameters: inlet temperature of 200°C, outlet temperature of 100°C, and PVA as the binder; the spray granulated powder was sintered at 1200°C for 4 hours to remove the organic binder layer.

[0062] The above four powders were added into the powder feeders of low-pressure plasma spraying equipment and atmospheric plasma spraying equipment respectively.

[0063] (4) A Si bonding layer was prepared on the substrate using low-pressure plasma spraying. The process parameters were adjusted as follows: argon flow rate of 40 L / min, hydrogen flow rate of 10 L / min, spraying distance of 300 mm, spraying current of 500 A, powder feeding rate of 25%, and vacuum chamber pressure of 200 Pa. Powder feeding was started when the substrate was preheated to 600°C, resulting in a Si bonding layer with a thickness of 75 μm.

[0064] (5) An atmospheric plasma spraying method was used to prepare a Yb2Si2O7 environmental barrier layer on the surface of the Si bonding layer. The process parameters were adjusted as follows: argon flow rate of 45 L / min, hydrogen flow rate of 10 L / min, spraying distance of 120 mm, spraying current of 650 A, and powder feeding rate of 25%, resulting in a Yb2Si2O7 environmental barrier layer with a thickness of 100 μm.

[0065] (6) β-LiAlSiO4-4(Gd 0.9 Yb 0.1 )2Zr2O7 transition layer, the process parameters were adjusted as follows: argon flow rate of 50L / min, hydrogen flow rate of 12L / min, spraying distance of 120mm, spraying current of 600A, powder feeding rate of 25%, and a β-LiAlSiO4-4(Gd 0.9 Yb 0.1 )2Zr2O7 transition layer.

[0066] (7) Using atmospheric plasma spraying method to deposit β-LiAlSiO4-4(Gd 0.9 Yb 0.1 )2Zr2O7 transition layer surface preparation (Gd 0.9 Yb 0.1)2Zr2O7 thermal barrier surface layer, the process parameters were adjusted as follows: argon flow rate of 50L / min, hydrogen flow rate of 12L / min, spraying distance of 120mm, spraying current of 600A, powder feeding rate of 25%, and a thickness of 100μm (Gd 0.9 Yb 0.1 )2Zr2O7 thermal barrier surface layer.

[0067] (8) The prepared coating was subjected to vacuum heat treatment, and the process parameters were adjusted to: temperature 1200 °C, time 4 h, vacuum degree 5×10 -3 Pa.

[0068] The thermal shock resistance test of the four-layer thermal / environmental barrier coating in Example 1 was carried out:

[0069] Thermal shock resistance was assessed at 1400°C, a flame velocity of Mach 0.5, a constant temperature of 120 seconds, and air cooling for 30 seconds. Failure was defined as significant flaking (flaking area greater than 10%). The results showed that the thermal / environmental barrier coating in this example had a thermal shock lifespan of 626 cycles.

[0070] Example 2

[0071] The process of Example 2 is basically the same as that of Example 1, except that:

[0072] In (3), the particle size of β-LiAlSiO4-4La2Zr2O7 powder is 5-50 μm (e.g. Figure 4 The particle size of La2Zr2O7 powder is 5-50μm. The powder morphology after granulation is porous spherical powder.

[0073] The preparation method of β-LiAlSiO4-4La2Zr2O7 powder is as follows:

[0074] (a) La2O3 and ZrO2 were mixed in a molar ratio of 1:2 and then wet-milled for 6 h at a speed of 400 r / min. -1 The milled slurry was dried in a drying oven at 75°C for 5 hours, manually ground, and passed through a 200-mesh sieve. The resulting powder was sintered at 1500°C for 5 hours.

[0075] (b) β-LiAlSiO4 powder and La2Zr2O7 powder were mixed in a weight ratio of 1:4 and then wet-milled for 4 h at a speed of 200 r / min. -1 , Place the ball-milled slurry in a drying oven at 75℃ and dry for 5h;

[0076] (c) The dried powder was spray granulated with the following parameters: inlet temperature of 200°C, outlet temperature of 100°C, and PVA as the binder; the spray granulated powder was sintered at 1200°C for 4 hours to remove the organic binder layer.

[0077] The preparation method of La2Zr2O7 powder is as follows:

[0078] (a) La2O3 and ZrO2 were mixed in a molar ratio of 1:2 and then wet-milled for 6 h at a speed of 400 r / min. -1 The milled slurry was dried in a drying oven at 75°C for 5 hours, manually ground, and passed through a 200-mesh sieve. The resulting powder was sintered at 1500°C for 5 hours.

[0079] (b) The dried powder was spray granulated with the following parameters: inlet temperature of 200°C, outlet temperature of 100°C, and PVA as the binder; the spray granulated powder was sintered at 1200°C for 4 hours to remove the organic binder layer.

[0080] In (6), an atmospheric plasma spraying method was used to prepare a β-LiAlSiO4-4La2Zr2O7 transition layer on the surface of the Yb2Si2O7 environmental barrier layer. The process parameters were adjusted as follows: the flow rate of argon was 50 L / min, the flow rate of hydrogen was 12 L / min, the spraying distance was 120 mm, the spraying current was 600 A, and the powder feeding rate was 25%. A β-LiAlSiO4-4La2Zr2O7 transition layer with a thickness of 100 μm was obtained.

[0081] In (7), the atmospheric plasma spraying method was used to prepare the La2Zr2O7 thermal barrier surface layer on the surface of the β-LiAlSiO4-4La2Zr2O7 transition layer. The process parameters were adjusted as follows: the flow rate of argon was 50 L / min, the flow rate of hydrogen was 12 L / min, the spraying distance was 120 mm, the spraying current was 600 A, and the powder feeding rate was 25%. A La2Zr2O7 thermal barrier surface layer with a thickness of 100 μm was obtained.

[0082] The thermal shock resistance of the thermal / environmental barrier coating prepared in this comparative example was tested using the same testing method as in Example 1, and the thermal shock resistance life was 502 cycles.

[0083] Example 3

[0084] The thermal / environmental barrier coating in this example is a three-layer structure, which is composed of Si bonding layer, Yb2Si2O7 environmental barrier layer and β-LiAlSiO4-3(Gd 0.9 Yb 0.1)2Zr2O7 thermal barrier layer. The process of Example 2 is basically the same as that of Example 1, except that (7) of Example 1 is omitted and β-LiAlSiO4-3(Gd 0.9 Yb 0.1 )2Zr2O7 thermal barrier surface layer, there are the following differences:

[0085] In (1), SiC f The size of the / SiC ceramic composite material matrix specimen is 20mm×10mm×3mm.

[0086] In (3), β-LiAlSiO4-3(Gd 0.9 Yb 0.1 )2Zr2O7 powder particle size is 5-50μm, and no (Gd 0.9 Yb 0.1 )2Zr2O7 powder.

[0087] In (5), the thickness of the Yb2Si2O7 environmental barrier layer is 150 μm.

[0088] In (6), β-LiAlSiO4-3(Gd 0.9 Yb 0.1 )2Zr2O7 thermal barrier layer thickness is 150μm.

[0089] The surface morphology of the three-layer thermal / environmental barrier coating in Example 2 is as follows: Figure 5 As shown, the thermal shock resistance test is carried out:

[0090] Thermal shock resistance was assessed by heating the coating at 1400°C for 5 minutes, followed by air cooling for 5 minutes. Failure was defined as significant flaking (greater than 10% flaking area). Results showed that the thermal / environmental barrier coating in this example had a thermal shock lifespan of 527 cycles.

[0091] Example 4

[0092] In addition, in order to illustrate the 0.9 Yb 0.1 β-LiAlSiO4 and (Gd 0.9 Yb 0.1 The influence of different weight ratios of )2Zr2O7 on the thermal expansion behavior of the thermal barrier surface layer and the thermal shock resistance of the thermal / environmental barrier coating was studied. The thermal expansion coefficient of the thermal barrier surface layer and the thermal shock resistance of the thermal / environmental barrier coating were also tested. The performance test results are shown in Table 1. It can be seen that:

[0093] β-LiAlSiO4-(Gd 0.9 Yb0.1 )2Zr2O7 thermal barrier layer β-LiAlSiO4 and (Gd 0.9 Yb 0.1 )2Zr2O7 weight ratio is 1:5~2:3, preferably 1:4~1:3. 0.9 Yb 0.1 When 2Zr2O7 is used in accordance with the above composition gradient, the obtained thermal barrier layer has good thermal matching with the environmental barrier layer and the substrate (the optimal value range of the thermal expansion coefficient under the system of the present invention is 4.5~6.5×10 -6 ·K -1 At the same time, the three-layer thermal / environmental barrier coating has excellent thermal shock resistance and a longer service life.

[0094] Table 1 Different weight ratios of β-LiAlSiO4-(Gd 0.9 Yb 0.1 )2Zr2O7 coating performance indicators

[0095]

[0096] Comparative Example 1

[0097] Comparative Example Compared with the embodiment, the Si bonding layer was prepared by atmospheric plasma spraying technology, and the specific preparation steps were as follows:

[0098] (1) Prepare SiC f The SiC / SiC ceramic composite matrix specimen, with a size of φ25 mm × 3 mm, was ultrasonically cleaned with acetone for 20 min and then dried.

[0099] (2) The ceramic matrix composite material was sandblasted before spraying. The sandblasting sand particles were 150 mesh quartz sand, the sandblasting pressure was 2 bar, and the sandblasting time was 20 s.

[0100] (3) A Si bonding layer was prepared on the substrate using atmospheric plasma spraying. The process parameters were adjusted to: argon flow rate of 35 L / min, hydrogen flow rate of 8 L / min, spray distance of 80 mm, spray current of 350 A, and powder feed rate of 25%. Powder feed was initiated when the substrate was preheated to 600°C, resulting in a Si bonding layer with a thickness of 75 μm.

[0101] The bonding strength of the Si bonding layer prepared by low-pressure plasma spraying in Example 1 or 2 and the Si bonding layer prepared in this comparative example was tested in accordance with GB / T 8642 2002. Samples 1, 2, and 3 were the Si bonding layers of either Example 1 or 2, and Samples 4, 5, and 6 were the coatings prepared in this comparative example. The results are shown in Table 2:

[0102] Table 2 Si bonding layer bonding strength in Example 1 or 2 and Comparative Example 1

[0103] Sample Bonding strength (MPa) Sample 1 26 Sample 2 24 Sample 3 27 Sample 4 16 Sample 5 13 Sample 6 15

[0104] As can be seen from Table 2, the average bonding strength between the environmental barrier coating and the substrate in this comparative example is 14.7 MPa, while the average bonding strength between the environmental barrier coating prepared in Example 3 and the substrate is 25.7 MPa, and the bonding strength is increased by nearly 75%.

[0105] Comparative Example 2

[0106] Comparative Example Compared with the embodiment, the atmospheric plasma spraying technology was used to prepare the Si bonding layer, Yb2Si2O7 environmental barrier layer and (Gd 0.9 Yb 0.1 )2Zr2O7 thermal barrier surface layer, the specific steps of preparation are as follows:

[0107] (1) Prepare SiC f The SiC / SiC ceramic composite matrix specimen, with a size of φ25 mm × 3 mm, was ultrasonically cleaned with acetone for 20 min and then dried.

[0108] (2) The ceramic matrix composite material was sandblasted before spraying. The sandblasting sand particles were 150 mesh quartz sand, the sandblasting pressure was 2 bar, and the sandblasting time was 20 s.

[0109] (3) The particle size of the Si powder after spray granulation is selected to be 15-45 μm, the particle size of the Yb2Si2O7 powder is 15-80 μm, and the (Gd 0.9 Yb 0.1 )2Zr2O7 powder particle size is 5-50μm. The above three powders are added to the powder feeder of the atmospheric plasma spraying equipment respectively.

[0110] (4) A Si bonding layer was prepared on the substrate using atmospheric plasma spraying. The process parameters were adjusted to: argon flow rate of 35 L / min, hydrogen flow rate of 8 L / min, spray distance of 80 mm, spray current of 350 A, and powder feed rate of 25%. Powder feed was initiated when the substrate was preheated to 600°C, resulting in a Si bonding layer with a thickness of 75 μm.

[0111] (5) The Yb2Si2O7 environmental barrier layer was prepared on the surface of the Si bonding layer by atmospheric plasma spraying. The process parameters were adjusted as follows: argon flow rate of 45 L / min, hydrogen flow rate of 10 L / min, spraying distance of 120 mm, spraying current of 650 A, and powder feeding rate of 25%, and a Yb2Si2O7 environmental barrier layer with a thickness of 150 μm was obtained.

[0112] (6) Atmospheric plasma spraying was used to prepare (Gd 0.9 Yb 0.1)2Zr2O7 thermal barrier surface layer, the process parameters were adjusted as follows: argon flow rate of 50L / min, hydrogen flow rate of 12L / min, spraying distance of 120mm, spraying current of 600A, powder feeding rate of 25%, and a thickness of 150μm (Gd 0.9 Yb 0.1 )2Zr2O7 thermal barrier surface layer.

[0113] (8) The prepared coating was subjected to vacuum heat treatment, and the process parameters were adjusted to: temperature 1200 °C, time 4 h, vacuum degree 5×10 -3 Pa.

[0114] The thermal shock resistance of the thermal / environmental barrier coating prepared in this comparative example was tested using the same testing method as in Example 1, and the thermal shock resistance life was 242 cycles.

[0115] Comparative Example 3

[0116] The preparation method of the thermal / environmental barrier coating in Comparative Example 3 is basically the same as that in Comparative Example 2, except that:

[0117] In (1), SiC f The size of the / SiC ceramic composite material matrix specimen is 20mm×10mm×3mm.

[0118] The shock resistance of the thermal / environmental barrier coating prepared in this comparative example was tested using the same testing method as in Example 2, and the thermal shock resistance life of the coating was 227 cycles.

[0119] The present invention has the following beneficial effects:

[0120] (1) The present invention adopts a low-pressure plasma spraying process to prepare the Si bonding layer, which effectively avoids the problem of Si oxidation during the spraying process. The obtained Si bonding layer has a dense structure, few defects such as internal voids and microcracks, and has a high bonding strength with the ceramic-based composite material.

[0121] (2) The β-LiAlSiO4-(RE1 x RE2 1-x )2Zr2O7 or (RE1 x RE2 1-x )2Zr2O7 thermal barrier surface layer has the characteristics of low thermal conductivity, good high temperature phase stability and stable chemical properties, which can play the role of heat insulation, resistance to molten salt corrosion and resistance to gas erosion, and prevent the heat in the gas environment from thermally eroding the inner coating; β-LiAlSiO4-(RE1 x RE2 1-xThe thermal expansion coefficient of the 2Zr2O7 transition layer is between that of the thermal barrier surface layer and the environmental barrier layer, which can alleviate the thermal expansion coefficient mismatch problem between the two; the Yb2Si2O7 environmental barrier layer can prevent water vapor from directly contacting the ceramic-based composite material, thereby improving the material's resistance to high-temperature water-oxygen corrosion; the Si bonding layer and the ceramic-based composite material have good high-temperature interface stability, which can improve the bonding strength between the thermal / environmental barrier coating and the substrate.

[0122] (3) The Si bonding layer, Yb2Si2O7 environmental barrier layer, β-LiAlSiO4-(RE1 x RE2 1-x )2Zr2O7 transition layer and (RE1 x RE2 1-x The thermal expansion coefficient gradient of the 2Zr2O7 thermal barrier surface layer increases, which effectively alleviates the accumulation of thermal stress during the hot and cold cycle and avoids the generation of defects such as microcracks inside the coating, thereby improving the thermal shock resistance and thermal shock resistance of the thermal / environmental barrier coating.

[0123] (4) By controlling the content of β-LiAlSiO4 and (RE1 x RE2 1-x )2Zr2O7 by weight ratio, which can realize the precise control of the thermal expansion coefficient of the transition layer or thermal barrier surface layer, and then flexibly select the three-layer structure system or the four-layer structure system according to the actual situation, which can be applied to the hot end components of ceramic matrix composites in different service conditions.

Claims

1. A thermal / environmental barrier coating that is resistant to thermal shock and thermal shock, characterized in that: The coating has a four-layer structure, which includes, from the inside to the outside, a Si bonding layer, a Yb2Si2O7 environmental barrier layer, a β-LiAlSiO4-(RE1 x RE2 1-x )2Zr2O7 transition layer and (RE1 x RE2 1-x )2Zr2O7 thermal barrier layer, and the transition layer β-LiAlSiO4 and (RE1 x RE2 1-x )2Zr2O7 weight ratio is 1:6 to 3:7, or The coating has a three-layer structure, which includes, from the inside to the outside, a Si bonding layer, a Yb2Si2O7 environmental barrier layer and a β-LiAlSiO4-(RE1 x RE2 1-x )2Zr2O7 thermal barrier layer, and the β-LiAlSiO4-(RE1 x RE2 1-x )2Zr2O7 thermal barrier layer β-LiAlSiO4 and (RE1 x RE2 1-x )2Zr2O7 weight ratio is 1:5~2:3, wherein 0≤x≤1, wherein RE1 and RE2 are respectively one of Gd, La, Nd, Yb, Dy, Sc and Sm.

2. The thermal / environmental barrier coating according to claim 1, wherein: When the coating is a four-layer structure, the β-LiAlSiO4 and (RE1 x RE2 1-x )2Zr2O7 weight ratio is 1:5 to 2:5; When the coating is a three-layer structure, the β-LiAlSiO4 and (RE1 x RE2 1-x )The weight ratio of 2Zr2O7 is 1:4~1:

3.

3. The thermal / environmental barrier coating according to claim 1, wherein: When the coating has a four-layer structure, the thickness of the Si bonding layer is 50 to 100 μm, the thickness of the Yb2Si2O7 environmental barrier layer is 80 to 120 μm, and the thickness of the β-LiAlSiO4-(RE1 x RE2 1-x )2Zr2O7 transition layer thickness is 80~120μm, said (RE1 x RE2 1-x )2Zr2O7 thermal barrier layer thickness is 80~120μm; When the coating has a three-layer structure, the thickness of the Si bonding layer is 50 to 100 μm, the thickness of the Yb2Si2O7 environmental barrier layer is 120 to 180 μm, and the thickness of the β-LiAlSiO4-(RE1 x RE2 1-x )The thickness of the 2Zr2O7 thermal barrier surface layer is 120~180μm.

4. A method for preparing a thermal / environmental barrier coating resistant to thermal shock and heat shock according to claim 1, characterized in that The following steps are involved: S1: Preparation of Si bonding layer on ceramic matrix composite using low-pressure plasma spraying process; S2: Using atmospheric plasma spraying process, Yb2Si2O7 environmental barrier layer, β-LiAlSiO4-(RE1 x RE2 1-x )2Zr2O7 transition layer and (RE1 x RE2 1-x )2Zr2O7 thermal barrier layer, or Yb2Si2O7 environmental barrier layer and β-LiAlSiO4-(RE1 x RE2 1-x )2Zr2O7 thermal barrier coating; S3: Vacuum heat treatment of ceramic matrix composites with thermal / environmental barrier coatings.

5. The preparation method according to claim 4, characterized in that Before preparing the Si bonding layer, the ceramic-based composite material is sandblasted with 100-200 mesh quartz sand, a sandblasting pressure of 1-3 bar, and a sandblasting time of 10-30 seconds. In addition, before sandblasting, the surface temperature of the ceramic-based composite material is heated to 500-800°C using a plasma flame flow.

6. The preparation method according to claim 4, characterized in that In step S1, the process parameters for preparing the Si bonding layer by low-pressure plasma spraying are: argon and hydrogen are used as plasma, the argon flow rate is 30-80 L / min, the hydrogen flow rate is 6-15 L / min, the spraying distance is 250-500 mm, the spraying current is 400-800 A, the powder feeding rate is 10-30%, the vacuum chamber pressure is 50-500 Pa, and the Si powder particle size is 10-60 μm.

7. The preparation method according to claim 4, characterized in that In step S2, the process parameters for preparing the Yb2Si2O7 environmental barrier layer by atmospheric plasma spraying are: argon and hydrogen are used as plasma, the argon flow rate is 40-60 L / min, the hydrogen flow rate is 6-15 L / min, the spraying distance is 100-150 mm, the spraying current is 600-1000 A, the powder feeding rate is 5-25%, and the Yb2Si2O7 powder particle size is 15-80 μm.

8. The preparation method according to claim 4, characterized in that In the step S2, β-LiAlSiO4-(RE1 x RE2 1-x )2Zr2O7 transition layer or β-LiAlSiO4-(RE1 x RE2 1-x The process parameters of )2Zr2O7 thermal barrier surface layer are as follows: argon and hydrogen are used as plasma, the flow rate of argon is 40-70L / min, the flow rate of hydrogen is 4-16L / min, the spraying distance is 80-150mm, the spraying current is 500-1000A, the powder feeding rate is 10-30%, β-LiAlSiO4-(RE1 x RE2 1-x )2Zr2O7 powder particle size is 5-50μm.

9. The preparation method according to claim 4, characterized in that In the step S2, atmospheric plasma spraying is performed to prepare (RE1 x RE2 1-x The process parameters of 2Zr2O7 thermal barrier surface layer are: argon and hydrogen as plasma, argon flow rate of 40-70L / min, hydrogen flow rate of 4-16L / min, spraying distance of 80-150mm, spraying current of 500-1000A, powder feeding rate of 10-30%, (RE1 x RE2 1-x )2Zr2O7 powder particle size is 5-50μm.

10. The preparation method according to claim 4, characterized in that In step S3, the heat treatment temperature is 1000-1200°C, the time is 4-6 hours, and the vacuum degree is 10 -3 Pa level.

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