Composite thermal barrier coating with multi-layer structure and preparation method and application of composite thermal barrier coating

Abstract

The invention discloses a composite thermal barrier coating of a multi-layer structure and a preparation method and application of the composite thermal barrier coating. The composite thermal barrier coating comprises a NiCrAlY bonding layer, an 8YSZ middle layer and a Y2Zr2O7-Y3Al5O12 ceramic top layer. Wherein the molar ratio of the Y3Al5O12 in the Y2Zr2O7-Y3Al5O12 ceramic top layer is 10%, and the molar ratio of the Y3Al5O12 in the Y2Zr2O7-Y3Al5O12 ceramic top layer is The coating is prepared by adopting an atmospheric plasma spraying process, and the composite thermal barrier coating with the multilayer structure solves the problems that the existing ceramic material is low in thermal expansion coefficient, poor in thermal matching with a bonding layer, poor in phase stability in a specific environment and the like. The coating is suitable for the surfaces of high-temperature parts such as aero-engines and gas turbines, and has excellent comprehensive thermal protection performance and long service life.

Description

Technical Field

[0001] This invention relates to a multilayer composite thermal barrier coating, its preparation method and application, belonging to the technical field of thermal barrier coating materials. Background Technology

[0002] Thermal barrier coatings are a key thermal protection technology for high-temperature components such as aero engines and gas turbines. By depositing a layer of ceramic material with low thermal conductivity and good high-temperature stability on its surface, the operating temperature of the metal substrate can be effectively reduced, significantly improving the engine's thermal efficiency and thrust-to-weight ratio, and extending the service life of core hot-end components. Currently, the most widely used and technologically mature thermal barrier coating material is 8 wt.% Y₂O₃-stabilized ZrO₂ (abbreviated as 8YSZ), but its long-term operating temperature is usually below 1200 °C.

[0003] As aero-engines and ground-based gas turbines develop towards higher efficiency and higher thrust, their turbine inlet temperatures continue to rise, placing more stringent demands on the service performance of thermal barrier coatings. Traditional 8YSZ coatings face the following severe challenges in ultra-high temperature (>1200 ℃) environments:

[0004] High-temperature phase transformation instability: 8YSZ undergoes harmful phase transformations at high temperatures, from non-equilibrium tetragonal phase to monoclinic and cubic phases, accompanied by a volume change of about 3-5%. This causes the coating to generate huge internal stress during thermal cycling, which in turn triggers the initiation and propagation of microcracks, ultimately leading to premature peeling and failure of the coating.

[0005] High-temperature sintering effect: Under long-term high-temperature exposure, the micropores and cracks in the 8YSZ coating will sinter and heal, resulting in the densification of the coating, which increases its Young's modulus, decreases its strain tolerance, and increases its thermal conductivity, thus significantly deteriorating its thermal insulation performance.

[0006] CMAS (Calcium Aluminum Sulfate) Melting Corrosion: After an engine ingests dust, sand, and other substances from the air, deposits of silicates, primarily composed of calcium, magnesium, and aluminum (mainly CaO, MgO, Al2O3, and SiO2, abbreviated as CMAS), form on the surface of high-temperature components. These deposits melt at approximately 1200–1250 °C, forming a glassy CMAS melt that rapidly penetrates into the pores and cracks of the coating. During cooling, the CMAS melt solidifies and crystallizes, generating significant thermal mismatch stress, leading to coating bulging, warping, and even peeling. Simultaneously, CMAS reacts chemically with the coating material, dissolving the stable phase and generating brittle reaction products (such as calcium aluminum feldspar Ca2Al2SiO7), severely damaging the structural integrity and bonding strength of the coating.

[0007] To address these challenges, researchers have developed novel ceramic materials such as zirconates and tantalates. However, these materials often suffer from low coefficients of thermal expansion, poor thermal compatibility with the binder layer, or poor phase stability under specific conditions. Therefore, developing a novel composite thermal barrier coating that combines excellent thermal cycling resistance, superior resistance to CMAS corrosion, and good high-temperature phase stability has become an urgent technological need in this field.

[0008] In view of the above-mentioned defects, the inventors of this invention have finally obtained this invention after a long period of research and practice. Summary of the Invention

[0009] The purpose of this invention is to solve the problems that current ceramic materials often have, such as low coefficient of thermal expansion, poor thermal matching with the adhesive layer, or poor phase stability under certain environments. The invention provides a multilayer composite thermal barrier coating, its preparation method, and its application.

[0010] To achieve the above objectives, this invention discloses a multilayer composite thermal barrier coating, which, from bottom to top, comprises a substrate, a NiCrAlY binder layer, an 8YSZ intermediate layer, and a Y2Zr2O7-Y3Al5O3 layer. 12 The ceramic top layer, the substrate being a nickel-based high-temperature alloy, the 8YSZ intermediate layer being ZrO2 stabilized with 8% by mass of Y2O3, and the Y2Zr2O7-Y3Al5O3... 12 The ceramic top layer consists of Y2Zr2O7 and Y3Al5O 12 The Y2Zr2O7-Y3Al5O 12 Y3Al5O in the top layer of ceramic 12 The molar ratio is 10%.

[0011] The mass percentage of the NiCrAlY adhesive layer is: Cr 22.0%, Al 11.0%, Y 1.0%, and Ni balance.

[0012] The NiCrAlY bonding layer, 8YSZ intermediate layer and Y2Zr2O7-Y3Al5O 12 The top layer of the ceramic is a layered structure.

[0013] The NiCrAlY bonding layer has a thickness of 100±10 μm, the 8YSZ intermediate layer has a thickness of 100±10 μm, and the Y2Zr2O7-Y3Al5O... 12 The thickness of the ceramic top layer is 200±10 μm.

[0014] This invention also discloses a method for preparing the above-mentioned multilayer composite thermal barrier coating, comprising the following steps:

[0015] S1, according to Y3Al5O 12Y2O3, Al2O3, and ZrO2 powders were calculated and weighed for a 10% molar ratio, and then prepared by spray granulation after thorough ball milling to obtain composite agglomerated powder.

[0016] S2, the nickel-based superalloy substrate is sequentially degreased, cleaned and sandblasted;

[0017] S3, NiCrAlY bonding layer is sprayed on the substrate using atmospheric plasma spraying method;

[0018] S4, an 8YSZ intermediate layer is sprayed onto the NiCrAlY bonding layer using an atmospheric plasma spraying method;

[0019] S5, Y2Zr2O7-Y3Al5O is sprayed onto the 8YSZ intermediate layer using atmospheric plasma spraying. 12 Ceramic top layer.

[0020] In step S3, the plasma spraying process parameters are: spraying distance 120 mm, Ar flow rate 40 L / min, powder feed rate 32 g / min, power 33 kW, spray gun speed 800 mm / s, current 460 A, and step size 4 mm.

[0021] In step S4, the plasma spraying process parameters are: spraying distance 80 mm, Ar flow rate 45 L / min, powder feed rate 30 g / min, power 40 kW, spray gun speed 500 mm / s, current 600 A, and step size 3 mm.

[0022] In step S5, the plasma spraying process parameters are: spraying distance 80 mm, Ar flow rate 40 L / min, powder feed rate 30 g / min, power 30 kW, spray gun speed 500 mm / s, current 600 A, and step size 3 mm.

[0023] The present invention also discloses the application of the above-mentioned multi-layer composite thermal barrier coating in high-temperature components of aero-engines and gas turbines.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] 1. High-temperature phase stability: The coating exhibits no phase change within the temperature range of 1100~1400 ℃, demonstrating its potential for long-term service.

[0026] 2. Excellent thermal cycling life: The composite thermal barrier coating in this invention significantly inhibits the propagation of transverse cracks in the coating during thermal cycling through grain boundary pinning and crack deflection mechanisms, thereby improving the coating's strain tolerance and interfacial bonding strength.

[0027] 3. Strong process compatibility: It adopts conventional atmospheric plasma spraying process, which is easy to realize industrial application. Attached Figure Description

[0028] Figure 1 XRD patterns of the composite coating at different times after sintering at 1400 °C;

[0029] Figure 2 The surface macroscopic morphology of the thermal barrier coating system after 542 cycles at 1100 ℃ in air.

[0030] Figure 3 The image shows the macroscopic surface morphology of the thermal barrier coating system after water quenching-thermal shock cycle test at 1100 ℃. Detailed Implementation

[0031] The above-mentioned and other technical features and advantages of the present invention will be described in more detail below with reference to the embodiments.

[0032] Example 1

[0033] The method for preparing a multilayer composite thermal barrier coating according to this embodiment includes the following steps:

[0034] S1, according to Y3Al5O 12 Y2O3, Al2O3, and ZrO2 powders were calculated and weighed for a 10% molar ratio, and then prepared by spray granulation after thorough ball milling to obtain composite agglomerated powder.

[0035] S2, the nickel-based superalloy substrate is sequentially degreased, cleaned and sandblasted;

[0036] S3, NiCrAlY bonding layer is sprayed on the substrate using atmospheric plasma spraying method. The plasma spraying process parameters are: spraying distance 120 mm, Ar flow rate 40 L / min, powder feed rate 32 g / min, power 33 kW, spray gun speed 800 mm / s, current 460 A, and step size 4 mm.

[0037] S4. An 8YSZ intermediate layer was sprayed on the NiCrAlY bonding layer using atmospheric plasma spraying. The plasma spraying process parameters were: spraying distance 80 mm, Ar flow rate 45 L / min, powder feed rate 30 g / min, power 40 kW, spray gun speed 500 mm / s, current 600 A, and step size 3 mm.

[0038] S5, Y2Zr2O7-Y3Al5O is sprayed onto the 8YSZ intermediate layer using atmospheric plasma spraying. 12 The plasma spraying process parameters for the ceramic top layer are as follows: spraying distance 80 mm, Ar flow rate 40 L / min, powder feed rate 30 g / min, power 30 kW, spray gun speed 500 mm / s, current 600 A, and step size 3 mm.

[0039] Anti-sintering performance test:

[0040] The obtained coated samples were placed in a box furnace and held at 1400 °C for 25, 50, 75, and 100 h, respectively, and characterized by XRD, along with the unheated prepared samples. Figure 1 The XRD patterns of the composite ceramic coating at different times after sintering at 1400 °C are shown.

[0041] Comparative Example 1

[0042] The preparation method of the coating in Comparative Example 1 includes the following steps:

[0043] S1. Based on the chemical formula of yttrium zirconate Y2Zr2O7, Y2O3 and ZrO2 powders were weighed in a molar ratio of 1:2, and agglomerated powder was prepared by spray granulation after thorough ball milling.

[0044] Repeat steps S2 to S4 in Example 1;

[0045] S5, an atmospheric plasma spraying method was used to spray the Y2Zr2O7 ceramic top layer onto the 8YSZ intermediate layer, with parameters consistent with step S5 in Example 1, to prepare a comparative coating sample.

[0046] Thermal cycling performance test:

[0047] The samples obtained in Example 1 and Comparative Example 1 were placed in a high-temperature tube furnace at 1100 °C and held for 50 min, then removed and air-cooled for 10 min; this constituted one cycle. Three parallel samples were prepared for each test group to avoid randomness. (Figure) Figure 2 As shown in the test results, after 542 cycles, the average peeling area of ​​the composite coating was 12.39%, while the average peeling area of ​​the sample coating in Comparative Example 1 was 31.89%, indicating that the peeling area of ​​the composite coating decreased by 19.5% during thermal cycling.

[0048] High-temperature water quenching-thermal shock cycle performance test:

[0049] The samples obtained in Example 1 and Comparative Example 1 were heated in a high-temperature furnace at 1100 °C for 10 min. After 10 min, the samples were quickly removed and poured into room-temperature water for rapid cooling; this was counted as one cycle. The samples were photographed every 5 cycles until 5% of the sample surface area detached, at which point the sample was considered invalid. Three parallel samples were prepared for each test group. Figure 3 As shown, the composite coating failed after 162 cycles, while the coating in Comparative Example 1 failed after 127 cycles, indicating that the composite coating lifetime was improved by 27.6%.

[0050] The above description is merely a preferred embodiment of the present invention and is illustrative rather than restrictive. Those skilled in the art will understand that many changes, modifications, and even equivalents can be made within the spirit and scope defined by the claims of the present invention, all of which will fall within the protection scope of the present invention.

Claims

1. A multilayer composite thermal barrier coating, characterized in that, From bottom to top, it includes a matrix, a NiCrAlY binder layer, an 8YSZ intermediate layer, and a Y2Zr2O7-Y3Al5O3 layer. 12 The ceramic top layer, the substrate being a nickel-based high-temperature alloy, the 8YSZ intermediate layer being ZrO2 stabilized with 8% by mass of Y2O3, and the Y2Zr2O7-Y3Al5O3... 12 The ceramic top layer consists of Y2Zr2O7 and Y3Al5O 12 The Y2Zr2O7-Y3Al5O 12 Y3Al5O in the top layer of ceramic 12 The molar percentage is 10%.

2. The multilayer composite thermal barrier coating as described in claim 1, characterized in that, The mass percentage of the NiCrAlY adhesive layer is: Cr 22.0%, Al 11.0%, Y 1.0%, and Ni balance.

3. The multilayer composite thermal barrier coating as described in claim 1, characterized in that, The NiCrAlY bonding layer, 8YSZ intermediate layer and Y2Zr2O7-Y3Al5O 12 The top layer of the ceramic is a layered structure.

4. The multilayer composite thermal barrier coating as described in claim 1, characterized in that, The NiCrAlY bonding layer has a thickness of 100±10 μm, the 8YSZ intermediate layer has a thickness of 100±10 μm, and the Y2Zr2O7-Y3Al5O3 layer has a thickness of 100±10 μm. 12 The thickness of the ceramic top layer is 200±10 μm.

5. A method for preparing a multilayer composite thermal barrier coating as described in any one of claims 1 to 4, characterized in that, Includes the following steps: S1, according to Y3Al5O 12 Y2O3, Al2O3, and ZrO2 powders were calculated and weighed for a 10% molar ratio, and then prepared by spray granulation after thorough ball milling to obtain composite agglomerated powder. S2, the nickel-based superalloy substrate is sequentially degreased, cleaned and sandblasted; S3, NiCrAlY bonding layer is sprayed on the substrate using atmospheric plasma spraying method; S4, an 8YSZ intermediate layer is sprayed onto the NiCrAlY bonding layer using an atmospheric plasma spraying method; S5, Y2Zr2O7-Y3Al5O is sprayed onto the 8YSZ intermediate layer using atmospheric plasma spraying. 12 Ceramic top layer.

6. The method for preparing a multilayer composite thermal barrier coating as described in claim 5, characterized in that, In step S3, the plasma spraying process parameters are: spraying distance 120 mm, Ar flow rate 40 L / min, powder feed rate 32 g / min, power 33 kW, spray gun speed 800 mm / s, current 460 A, and step size 4 mm.

7. The method for preparing a multilayer composite thermal barrier coating as described in claim 5, characterized in that, In step S4, the plasma spraying process parameters are: spraying distance 80 mm, Ar flow rate 45 L / min, powder feed rate 30 g / min, power 40 kW, spray gun speed 500 mm / s, current 600 A, and step size 3 mm.

8. The method for preparing a multilayer composite thermal barrier coating as described in claim 5, characterized in that, In step S5, the plasma spraying process parameters are: spraying distance 80 mm, Ar flow rate 40 L / min, powder feed rate 30 g / min, power 30 kW, spray gun speed 500 mm / s, current 600 A, and step size 3 mm.

9. The application of a multi-layer composite thermal barrier coating as described in any one of claims 1 to 4 in high-temperature components of aero engines and gas turbines.

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