Nanostructured thermal protection coating for hydrogen fuel gas turbine and method for producing the same

Abstract

The application discloses a nano-structure thermal protection coating for hydrogen fuel gas turbine and a preparation method thereof. The nano-structure thermal protection coating takes high-temperature alloy as a substrate, and sequentially deposits a bonding bottom layer, a yttrium stabilized zirconium oxide or zirconate intermediate layer and a silicate top layer on the surface of the substrate. The application starts from the design of the coating structure, and aims at the problems of low service temperature and poor water-oxygen corrosion resistance of the existing thermal protection coating for gas turbine. The water-oxygen corrosion resistance function of the silicate material is superimposed on the thermal protection coating for gas turbine, and the coating structure is optimized to form a new thermal protection coating structure resistant to high-temperature corrosion. The new thermal protection coating structure can not only meet more extreme service environments, but also resist water-oxygen corrosion at high temperature. The new thermal protection coating structure is suitable for hydrogen fuel power generation gas turbine, and is also suitable for hydrogen fuel or hydrogen mixed marine engines, hydrogen fuel rocket engines and other hydrogen fuel gas turbines.

Description

Technical Field

[0001] This invention relates to a high-temperature thermal protection coating, specifically to a nanostructured thermal protection coating for hydrogen fuel cell gas turbines and its preparation method. Background Technology

[0002] The most promising direction for achieving carbon neutrality is the clean and low-carbon transformation of the energy structure, with clean and renewable energy becoming the main direction of energy development. The power generation industry is a major source of global greenhouse gas emissions and has therefore been identified as a key target industry for carbon dioxide emission reduction. The power generation market is currently undergoing a significant transformation towards renewable energy and decarbonization. Gas turbine power plants, whether open-cycle, combined cycle, or cogeneration, offer the highest efficiency and are suitable for various power outputs. The power generation market's requirements for gas turbine units have consistently focused on improving efficiency, increasing power output, and reducing emissions. Among these, hydrogen gas turbines, with their advantages of zero carbon emissions and flexible controllability, will become a crucial force in the new power grid during the carbon peaking process and the carbon neutrality era. Research on developing high-power gas turbines capable of burning 100% hydrogen fuel has entered a large-scale R&D phase, and gas turbine manufacturing is ushering in a new period of development opportunities.

[0003] Incorporating hydrogen into gas turbines not only reduces the use of non-renewable energy sources (methane, associated gas from oil wells, etc.) but also effectively reduces carbon dioxide emissions during power generation. Simultaneously, it can increase turbine inlet temperature for higher efficiency. From green hydrogen production to power generation using hydrogen gas turbines, the entire process achieves clean, sustainable, and low-carbon development. For F-class and H-class heavy-duty gas turbines, combustion chamber temperatures are 1400 ℃ and 1600 ℃, respectively. When the mixed fuel is injected at a certain mass flow rate, the combustion chamber outlet temperature increases further with increasing hydrogen content. Therefore, to achieve near-zero emission gas turbine technology in the future, progress is needed in thermal protection coating technology. Furthermore, hydrogen combustion increases the moisture content in the products, making hot-end components more susceptible to water-oxygen corrosion at high temperatures, leading to component failure and shortened service life. With increasing hydrogen content, thermal corrosion and water-oxygen corrosion become more severe, and existing materials are insufficient to meet the practical application requirements of service temperatures >1200 ℃.

[0004] To a large extent, the lifespan of thermal protective coatings determines the lifespan of the entire high-temperature component. The failure and spalling of traditional thermal protective coatings at high temperatures is their biggest problem in gas turbines, severely limiting their application. This is due to poor coating preparation, insufficient adhesion between the coating and the base metal, and an inability to withstand excessive temperature changes and thermal stress during use. Furthermore, corrosion and oxidation of traditional thermal protective coatings in high-temperature and gaseous environments can also lead to localized or complete failure of the coating surface. Therefore, it is necessary to optimize the composition and structure of thermal protective coatings. Optimizing the composition can increase the coating's operating temperature, while gradient composition distribution can significantly reduce or eliminate internal interfaces within the coating, alleviate internal stress, and greatly extend the coating's lifespan to meet practical application requirements.

[0005] The use of nanotechnology combined with coating preparation techniques to prepare ceramic coatings can effectively utilize the excellent properties of ceramics, further improving coating lifespan and stability, and greatly expanding the application range of ceramic coatings. Nanostructured thermal protective coatings, especially those prepared using thermal spraying technology, have gradually attracted attention due to their superior performance compared to traditional structural coatings: firstly, the nanoscale grain size leads to a sharp increase in grain boundaries, resulting in enhanced phonon scattering within the crystal lattice and thus reducing the coating's thermal conductivity; secondly, nanostructured thermal protective coatings possess excellent mechanical properties, improving coating reliability and extending its service life. Our research group is dedicated to the study of nanostructured thermal protective coatings and has achieved certain results. For example, Wei Fushuang et al. prepared high-entropy ceramic materials with small grain size and resistant to CMAS corrosion through a one-step pressureless sintering synthesis method, and pointed out that reducing the grain size in ceramic materials can significantly improve the mechanical properties of the materials (Invention Patent: A high-entropy ceramic material with small grain size and resistant to CMAS corrosion and its preparation method, CN 114671675 B); Zhang Xiaodong et al. prepared Yb2Si2O7 powder with nanostructure using solid-state sintering process. The powder has high purity and well-preserved nanostructure, and can be used as a high-performance nanostructure environmental barrier coating material for aero-engines and gas turbines (Invention Patent: A high-purity nanostructured ytterbium disilicate powder and its preparation method, CN 115557511 A).

[0006] Therefore, by fully leveraging the potential of nanostructured materials as thermal protective coatings and optimizing the composition and structure of thermal protective coatings to better meet the requirements of thermal protective coatings for novel hydrogen fuel gas turbines, this invention designs a novel nano-thermal protective coating structure that is resistant to water and oxygen corrosion at higher temperatures. Summary of the Invention

[0007] To address the problem that current thermal protection coatings on hydrogen fuel cell gas turbines cannot meet the operating requirements above 1200 °C, have unsatisfactory high-temperature corrosion resistance, and have resulted in multiple instances of coating detachment in practical applications, severely impacting unit operation, this invention provides a nanostructured thermal protection coating for hydrogen fuel cell gas turbines and its preparation method. Starting from the coating structure design, this invention addresses the issues of low operating temperature and poor resistance to water and oxygen corrosion in existing gas turbine thermal protection coatings. By superimposing the water and oxygen corrosion resistance of silicate materials onto the gas turbine thermal protection coating, and through optimized coating structure design, a novel high-temperature corrosion resistant thermal protection coating structure is formed. This structure not only meets the requirements of more extreme service environments (>1300 °C) but also resists water and oxygen corrosion at high temperatures. The three-layer coating prepared by this invention exhibits a gradual decrease in the coefficient of thermal expansion and thermal conductivity from the substrate to the top layer. This not only demonstrates good compatibility between the layers of the thermal protective coating, but also, because the top layer is a silicate coating, it exhibits superior resistance to water and oxygen corrosion at high temperatures. This makes it suitable not only for gas turbines used in hydrogen fuel power generation, but also for various hydrogen fuel gas turbines such as hydrogen-fueled or mixed-hydrogen marine gas turbines and hydrogen-fueled rocket engines.

[0008] The objective of this invention is achieved through the following technical solution:

[0009] A nanostructured thermal protection coating for hydrogen fuel cell gas turbines uses a high-temperature alloy as a substrate. On the substrate surface, a bonding underlayer, a yttrium-stabilized zirconium oxide (YSZ) or zirconate (RE2Zr2O7) intermediate layer, and a silicate top layer are sequentially deposited, wherein:

[0010] The base has a diameter of 25.4 mm and a thickness of 3~20 mm, and the high-temperature alloy can be one or more of iron-based high-temperature alloys, nickel-based high-temperature alloys, and cobalt-based high-temperature alloys;

[0011] The bonding underlayer is selected from MCrAlY, such as one or more of NiCrAlY, CoCrAlY, NiCoCrAlY, NiCrAlYCe, NiCrAlYSi, NiCrAlYSiCe, and CoCrAlYCe, to improve the thermal compatibility between the ceramic coating and the metal substrate.

[0012] The YSZ intermediate layer is selected from nanostructured YSZ or rare earth modified nanostructured YSZ, and the rare earth elements are one or more of Ce, Sc, Gd, La, Er, and Yb, which are used to improve the thermal protection effect, phase stability and thermal shock resistance of the coating.

[0013] The zirconate intermediate layer is a nanostructured rare earth zirconate, which is composed of four or more elements selected from Sc, Y, Ce, Pr, Pm, Sm, Eu, Tb, Dy, Ho, Er, Yb and Lu to form high-entropy RE2Zr2O7. Spherical powder is prepared by spray granulation technology, and the powder sphere diameter is between 10 and 70 μm.

[0014] The silicate top layer is a nanostructured Yb2SiO5, which is prepared by spray granulation technology using nanomaterials, with a spherical diameter distribution of 10~70 μm. Depending on the application environment, nanostructured Y2SiO5, Yb2Si2O7 or Y2Si2O7 can also be selected as the top layer of the corrosion-resistant heat protection coating, with a spherical diameter distribution of 10~70 μm.

[0015] The raw material powders used for the bonding bottom layer, yttrium-stabilized zirconium oxide (YSZ) or zirconate (RE2Zr2O7) intermediate layer and silicate top layer are of 4N purity and are prepared by spray granulation.

[0016] A method for preparing the above-mentioned nanostructured thermal protective coating for hydrogen fuel cell gas turbines includes the following steps:

[0017] Step 1: Treat the substrate surface by fine grinding, ultrasonically clean it with alcohol or acetone, and then sandblast or laser process the smooth surface to improve its roughness. After the roughness meets the requirements for spraying, continue ultrasonic cleaning and dry it in an oven at 60~80 ℃ for later use.

[0018] Step 2: Spray an MCrAlY bonding underlayer onto the substrate surface. The spraying method can be one or more of atmospheric plasma spraying (APS), electron beam physical vapor deposition (EB-PVD), high-velocity vapor deposition (HVOF), and plasma-physical vapor deposition (PS-PVD). When using high-velocity vapor deposition (HVOF), the bonding underlayer preparation parameters are as follows: N2 as the carrier gas, with a carrier gas flow rate of 16~20 NLPM, a shielding gas flow rate of 330~370 NLPM, a methane flow rate of 160~190 NLPM, a powder feed rate of 30~40 g / min, and a spraying distance of 200~300 mm; the bonding underlayer thickness is 80~120 μm.

[0019] Step 3: Spray-coated yttrium-stabilized zirconia or zirconate powder is deposited on the surface of the bonding substrate to obtain a yttrium-stabilized zirconia or zirconate intermediate layer. The spraying method can be one or more of atmospheric plasma spraying (APS), electron beam physical vapor deposition (EB-PVD), high-velocity oxygen fuel (HVOF), and plasma-physical vapor deposition (PS-PVD). When using atmospheric plasma spraying (APS), the preparation parameters for the yttrium-stabilized zirconia or zirconate intermediate layer are: spraying current of 600-750A, voltage of 60-75V, spraying power of 40-55KW, argon as the main gas with a flow rate of 35-45 SCFH, hydrogen as the auxiliary gas with a flow rate of 8-12 SCFH, rotary powder feeding mode with a rotary speed of 30-40 r / min, and carrier gas flow rate of 2-3 SCFH; the intermediate layer thickness is 120-200 μm.

[0020] Step 4: Spray-deposit nanostructured Yb₂SiO₅, Y₂SiO₅, Yb₂Si₂O₇, or Y₂Si₂O₇ sprayable powder onto the surface of yttrium-stabilized zirconia or zirconate interlayer to obtain a silicate top layer. This process aims to prepare a novel structural coating that can extend the service life of high-temperature alloy components for hydrogen gas turbines operating in high-temperature environments. The spraying method employs one or more of atmospheric plasma spraying (APS), electron beam physical vapor deposition (EB-PVD), high-velocity oxygen fuel (HVOF), and plasma-physical vapor deposition (PS-PVD). When using atmospheric plasma spraying (APS), the preparation parameters for the yttrium-stabilized zirconia or zirconate interlayer are: spraying current of 580–650 A, voltage of 65–75 V, spraying power of 38–48 kW, argon as the main gas with a flow rate of 38–46 SCFH, and hydrogen as the auxiliary gas with a flow rate of 8–15 SCFH. SCFH, the powder feeding mode adopts a rotary table, the rotary table speed is 25~35 r / min, the carrier gas flow rate is 2~3 SCFH; the silicate top layer thickness is 40~70 μm.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] 1. As the proportion of hydrogen added to hydrogen gas turbines for power generation increases, the combustion chamber outlet temperature rises accordingly, posing a more severe threat of thermal corrosion and water-oxygen corrosion to the substrate materials. Existing thermal protection coating materials are insufficient to meet the requirements for use above 1200℃. Based on the requirements of the coating service environment, this invention proposes a concept for constructing a novel corrosion-resistant / high-temperature-resistant nanostructured thermal protection coating on the surface of high-temperature alloys, specifically addressing the service life problem of various high-temperature alloy components in hydrogen fuel cell gas turbines at high temperatures.

[0023] 2. Based on the requirements of the coating service environment, this invention first constructs a novel nanostructured thermal protection coating on the surface of high-temperature alloys that is corrosion-resistant and high-temperature resistant: the top layer is made of silicate material that is more resistant to water and oxygen corrosion and meets the requirements of more extreme service environments (>1300 ℃), the middle layer is made of yttrium-stabilized zirconium oxide (YSZ) or zirconate material with good heat insulation effect and matching coefficient of thermal expansion, and the materials selected for the bonding layer make the entire coating not only innovative in structure, but also meet the requirements of more extreme service environments in terms of performance.

[0024] 3. The entire coating structure of this invention exhibits a gradient decrease in the coefficient of thermal expansion and thermal conductivity from the substrate to the silicate top layer, resulting in high thermal stress matching and tight bonding between layers. This effectively addresses the service life issues of various high-temperature alloy components for hydrogen fuel cell gas turbines at high temperatures. Each coating structure possesses a distinct dual-modal structure, namely an unmelted zone and a molten zone. The combination of these two structures creates porosity within the coating, further enhancing its thermal insulation and strain tolerance.

[0025] 4. The silicate top layer and yttrium-stabilized zirconium oxide (YSZ) or zirconate intermediate layer materials used in this invention are all nanostructured raw materials, prepared by spray granulation. The introduction of nanostructures improves the strain tolerance of the coating and makes the internal pore structure of the coating more uniform. Attached Figure Description

[0026] Figure 1 The preparation process of the thermal protective coating of this invention;

[0027] Figure 2 The images show the overall cross-sectional scanning electron microscope (SEM) image and secondary electron spectrometry (SEES) image of the three-layer thermal protective coating with a Yb2SiO5 silicate top layer, a YSZ intermediate layer, and an MCrAlY bonding bottom layer prepared in Example 1.

[0028] Figure 3 It is the Yb2SiO5 silicate top layer prepared in Example 2, (Sm 0.2 Eu 0.2 Tb 0.2 Dy 0.2 L u0.2 Scanning electron microscope (SEM) image and secondary electron spectrometry (SEES) image of the overall cross-section of the three-layer thermal protective coating consisting of a Zr2O7 intermediate layer and an MCrAlY bonding underlayer;

[0029] Figure 4 These are macroscopic photographs of several ceramic materials before and after water-oxygen corrosion. Detailed Implementation

[0030] The technical solution of the present invention will be further described below with reference to the embodiments, but it is not limited thereto. Any modifications or equivalent substitutions to the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention should be covered within the protection scope of the present invention.

[0031] Example 1:

[0032] This embodiment provides a method for preparing a thermally protective coating using nanostructured YSZ as an intermediate layer, such as... Figure 1 As shown, the method includes the following steps:

[0033] Step 1: Finely grind the surface of the GH3230 substrate using 400-800 mesh SiC sandpaper, then ultrasonically clean it with alcohol or acetone for 5 minutes. Next, use SiC abrasive particles to sandblast the smooth surface to improve its roughness, achieving a roughness value between 2.00 and 4.00 μm. After achieving the required roughness for spraying, ultrasonically clean it with alcohol for 3 minutes and then dry it in a 70°C oven until ready for use.

[0034] Step 2: A NiCrAlY alloy bonding underlayer was prepared on the substrate surface treated in Step 1 using high-velocity vapor deposition (HVOF) technology. The bonding underlayer preparation parameters were as follows: N2 carrier gas with a flow rate of 18 NLPM, shielding gas flow rate of 350 NLPM, methane flow rate of 175 NLPM, powder feed rate of 35 g / min, and spraying distance of 250 mm. After spraying, the thickness of the bonding underlayer was measured using a micrometer, and the average value was measured at 10 points on the bonding underlayer surface. The thickness of the NiCrAlY alloy bonding underlayer was 103 μm.

[0035] Step 3: Using atmospheric plasma spraying (APS), the sieved nanostructured YSZ sprayable powder is deposited onto the surface of the bonding underlayer prepared in Step 4, obtaining the nanostructured thermal protection intermediate layer in the coating structure. The preparation parameters for the nanostructured thermal protection intermediate layer are as follows: spraying current 600 A, voltage 77 V, spraying power 45.9 kW, argon as the main gas with a flow rate of 42 SCFH, hydrogen as the auxiliary gas with a flow rate of 12 SCFH, rotary powder feeding mode with a rotary speed of 27 r / min, and carrier gas flow rate of 2.5 SCFH. After spraying, the thickness is measured using a micrometer, and the average value is measured at 10 points on the surface of the thermal protection intermediate layer. The thickness of the YSZ thermal protection intermediate layer is 160 μm.

[0036] Step 4: Using atmospheric plasma spraying (APS), the sieved nanostructured Yb₂SiO₅ sprayable powder is deposited onto the surface of the heat-protective intermediate layer prepared in Step 5, obtaining the nanostructured silicate top layer of the coating structure. The preparation parameters for the nanostructured silicate top layer are as follows: spraying current 620 A, voltage 72.5 V, spraying power 43.5 kW, argon as the main gas with a flow rate of 42 SCFH, hydrogen as the auxiliary gas with a flow rate of 12.5 SCFH, rotary powder feeding mode with a rotary speed of 30 r / min, and carrier gas flow rate of 3 SCFH. After spraying, the thickness is measured using a micrometer, and the average value is measured at 10 points on the surface of the silicate top layer. The thickness of the Yb₂SiO₅ silicate top layer coating is 50 μm.

[0037] Depend on Figure 2 It can be seen that: the NiCrAlY alloy bonding underlayer has good adhesion to the substrate; the NiCrAlY alloy bonding underlayer has tight adhesion to the YSZ thermal protection intermediate layer with no obvious defects; and the silicate top layer has good adhesion to the YSZ thermal protection intermediate layer.

[0038] Example 2:

[0039] This embodiment provides a method for preparing a heat-protective coating using nanostructured zirconate as a heat-protective intermediate layer, such as... Figure 1 As shown, the method includes the following steps:

[0040] Step 1: Finely grind the surface of the GH3230 substrate using 400-800 mesh SiC sandpaper, then ultrasonically clean it for 5 minutes with alcohol or acetone. Next, sandblast the smooth surface with SiC abrasive to improve its roughness, achieving a roughness value between 2.00 and 4.00 μm. After achieving the required roughness for spraying, ultrasonically clean it with alcohol for 3 minutes and dry it in a 70°C oven until ready for use.

[0041] Step 2: A NiCrAlY alloy bonding underlayer was prepared on the substrate surface treated in Step 1 using high-velocity vapor deposition (HVOF) technology. The bonding underlayer preparation parameters were as follows: N2 carrier gas with a flow rate of 18 NLPM, shielding gas flow rate of 350 NLPM, methane flow rate of 175 NLPM, powder feed rate of 35 g / min, and spraying distance of 250 mm. After spraying, the thickness of the bonding underlayer was measured using a micrometer, and the average value was measured at 10 points on the surface of the NiCrAlY alloy bonding underlayer. The thickness of the NiCrAlY coating was 98 μm.

[0042] Step 3: Apply atmospheric plasma spraying (APS) to the sieved nanostructures (Sm) 0.2 Eu 0.2 Tb 0.2 Dy 0.2L u0.2 Sprayable Zr₂O₇ powder was deposited onto the surface of the bonding underlayer prepared in step four to obtain a nanostructured thermal protective intermediate layer in the coating structure. The preparation parameters for the nanostructured thermal protective intermediate layer were: spraying current of 700 A, voltage of 72.5 V, spraying power of 50.6 KW, argon as the main gas with a flow rate of 42 SCFH, hydrogen as the auxiliary gas with a flow rate of 10 SCFH, rotary powder feeding mode with a rotary speed of 35 r / min, and carrier gas flow rate of 2.5 SCFH. After spraying, the thickness was measured using a micrometer, and the average value was measured at 10 points on the surface of the thermal protective intermediate layer. The thermal protective intermediate layer (Sm... 0.2 Eu 0.2 Tb 0.2 Dy 0.2 L u0.2 The thickness of the 2Zr2O7 coating is 157 μm.

[0043] Step 4: Using atmospheric plasma spraying (APS), the sieved nanostructured Yb₂SiO₅ sprayable powder is deposited onto the surface of the heat-protective intermediate layer prepared in Step 5, obtaining the nanostructured silicate top layer of the coating structure. The preparation parameters for the nanostructured silicate top layer are as follows: spraying current 620 A, voltage 72.5 V, spraying power 43.5 kW, argon as the main gas with a flow rate of 42 SCFH, hydrogen as the auxiliary gas with a flow rate of 12.5 SCFH, rotary powder feeding mode with a rotary speed of 30 r / min, and carrier gas flow rate of 3 SCFH. After spraying, the thickness is measured using a micrometer, and the average value is measured at 10 points on the silicate surface. The thickness of the Yb₂SiO₅ silicate top layer coating is 53 μm.

[0044] Depend on Figure 3 It can be seen that: the NiCrAlY alloy bonding underlayer has good adhesion to the substrate; the NiCrAlY alloy bonding underlayer has tight adhesion to the zirconate thermal protection intermediate layer with no obvious defects, and rare earth elements are evenly distributed in the thermal protection intermediate layer; the silicate top layer has good adhesion to the thermal protection intermediate layer.

[0045] Water-oxygen corrosion test: Three types of pressed and sintered circular ceramic materials were selected and subjected to water-oxygen corrosion test at 1550 °C. o A 48-hour water-oxygen corrosion test was conducted under C conditions. Observation of the sample surfaces before and after water-oxygen corrosion showed that the water-oxygen corrosion resistance of YSZ, Gd2Zr2O7, and Yb2SiO5 increased in that order, with Yb2SiO5 exhibiting significantly better water-oxygen corrosion resistance than the other materials. Figure 4 As shown.

[0046] Example 3:

[0047] This embodiment provides a method for preparing a thermally protective coating with nanostructured Yb₂Si₂O₇ as the silicate top layer, such as... Figure 1 As shown, the method includes the following steps:

[0048] Step 1: Finely grind the surface of the GH3230 substrate using 400-800 mesh SiC sandpaper, then ultrasonically clean it with alcohol or acetone for 5 minutes. Next, use SiC abrasive particles to sandblast the smooth surface to improve its roughness, achieving a roughness value between 2.00 and 4.00 μm. After achieving the required roughness for spraying, ultrasonically clean it with alcohol for 3 minutes and then dry it in a 70°C oven until ready for use.

[0049] Step 2: A NiCrAlY alloy bonding underlayer was prepared on the substrate surface treated in Step 1 using high-velocity vapor deposition (HVOF) technology. The bonding underlayer preparation parameters were as follows: N2 carrier gas with a flow rate of 18 NLPM, shielding gas flow rate of 350 NLPM, methane flow rate of 175 NLPM, powder feed rate of 35 g / min, and spraying distance of 250 mm. After spraying, the thickness of the bonding underlayer was measured using a micrometer, and the average value was measured at 10 points on the surface of the NiCrAlY alloy bonding underlayer. The thickness of the NiCrAlY coating was 102 μm.

[0050] Step 3: Apply atmospheric plasma spraying (APS) to the sieved nanostructures (Sm) 0.2 Eu 0.2 Tb 0.2 Dy 0.2 L u0.2 The sprayable Zr₂O₇ powder was deposited onto the surface of the bonding underlayer prepared in step four to obtain a nanostructured zirconate thermal protection interlayer in the coating structure. The preparation parameters for the nanostructured zirconate thermal protection interlayer were as follows: spraying current of 700 A, voltage of 72.5 V, spraying power of 50.6 KW, argon as the main gas with a flow rate of 42 SCFH, hydrogen as the auxiliary gas with a flow rate of 10 SCFH, rotary powder feeding mode with a rotary speed of 35 r / min, and carrier gas flow rate of 2.5 SCFH. After spraying, the thickness was measured using a micrometer, and the average value was measured at 10 points on the surface of the zirconate thermal protection interlayer. The zirconate interlayer (Sm) 0.2 Eu 0.2 Tb 0.2 Dy 0.2 L u0.2 The thickness of the 2Zr2O7 coating is 155 μm.

[0051] Step 4: Using atmospheric plasma spraying (APS), the sieved nanostructured Yb₂Si₂O₇ sprayable powder is deposited onto the surface of the zirconate thermal protection intermediate layer prepared in Step 5, obtaining the nanostructured silicate top layer in the coating structure. The preparation parameters for the nanostructured silicate top layer are as follows: spraying current 600 A, voltage 65 V, spraying power 39 kW, argon as the main gas with a flow rate of 42 SCFH, hydrogen as the auxiliary gas with a flow rate of 10 SCFH, rotary powder feeding mode with a rotary speed of 32 r / min, and carrier gas flow rate of 2.5 SCFH. After spraying, the thickness is measured using a micrometer, and the average value is measured at 10 points on the silicate surface. The thickness of the Yb₂Si₂O₇ silicate top layer coating is 53 μm.

[0052] Example 4:

[0053] The difference between this embodiment and embodiments 1-3 is that CoCrAlY, NiCoCrAlY, NiCrAlYCe, NiCrAlYSi, NiCrAlYSiCe, or CoCrAlYCe are selected as the bonding substrate.

[0054] Example 5:

[0055] The difference between this embodiment and Embodiment 4 is that nanostructured Ce-modified YSZ is selected as the thermal protection intermediate layer.

[0056] Example 6:

[0057] The difference between this embodiment and Embodiment 4 is that a nanostructure (Gd) is selected. 0.2 La 0.2 Pm 0.2 Ho 0.2 Ce 0.2 )2Zr2O7 is used as a thermal protection intermediate layer.

[0058] Example 7:

[0059] The difference between this embodiment and embodiments 5 and 6 is that a nanostructure of Y2SiO5 or Y2Si2O7 is selected as the silicate top layer.

Claims

1. A nanostructured thermal protection coating for hydrogen fuel cell gas turbines, characterized in that... The nanostructured thermal protective coating uses a high-temperature alloy as the substrate, and a bonding underlayer, a zirconate intermediate layer, and a silicate top layer are sequentially deposited on the substrate surface. The zirconate intermediate layer is a nanostructured rare-earth zirconate. The nanostructured rare-earth zirconate is composed of four or more elements selected from Sc, Y, Ce, Pr, Pm, Sm, Eu, Tb, Dy, Ho, Er, Yb, and Lu to form a high-entropy RE2Zr2O7. The silicate top layer is a nanostructured Yb2SiO5, Y2SiO5, Yb2Si2O7, or Y2Si2O7. The specific preparation steps are as follows: Step 1: Treat the substrate surface by fine grinding, ultrasonically clean it with alcohol or acetone, and then sandblast or laser process the smooth surface to improve its roughness. After the roughness meets the requirements for spraying, continue ultrasonic cleaning and dry it in an oven at 60~80 ℃ for later use. Step 2: Spray MCrAlY bonding primer onto the substrate surface; Step 3: Spray-coated zirconate powder is deposited on the surface of the bonding substrate to obtain a zirconate intermediate layer. The powder sphere diameter is between 10 and 70 μm, and it is prepared by spray granulation. Step 4: Spray-coated nanostructured Yb2SiO5, Y2SiO5, Yb2Si2O7 or Y2Si2O7 onto the surface of the zirconate intermediate layer to obtain the silicate top layer. The powder sphere diameter is between 10 and 70 μm, and it is prepared by spray granulation.

2. The nanostructured thermal protection coating for hydrogen fuel cell gas turbines according to claim 1, characterized in that... The base has a diameter of 25.4 mm and a thickness of 3-20 mm, and the high-temperature alloy is one or more of iron-based high-temperature alloys, nickel-based high-temperature alloys, and cobalt-based high-temperature alloys.

3. The nanostructured thermal protection coating for hydrogen fuel cell gas turbines according to claim 1, characterized in that... The bonding substrate is MCrAlY, and MCrAlY is one or more of NiCrAlY, CoCrAlY, NiCoCrAlY, NiCrAlYCe, NiCrAlYSi, NiCrAlYSiCe, and CoCrAlYCe.

4. The nanostructured thermal protection coating for hydrogen fuel cell gas turbines according to claim 1, characterized in that... The thickness of the bonding underlayer is 80~120 μm, the thickness of the zirconate intermediate layer is 120~200 μm, and the thickness of the silicate top layer is 40~70 μm.

5. A method for preparing a nanostructured thermal protective coating for a hydrogen fuel cell gas turbine according to any one of claims 1-4, characterized in that... The method includes the following steps: Step 1: Treat the substrate surface by fine grinding, ultrasonically clean it with alcohol or acetone, and then sandblast or laser process the smooth surface to improve its roughness. After the roughness meets the requirements for spraying, continue ultrasonic cleaning and dry it in an oven at 60~80 ℃ for later use. Step 2: Spray MCrAlY bonding primer onto the substrate surface; Step 3: Spray-coated zirconate powder is deposited on the surface of the bonding substrate to obtain a zirconate intermediate layer. The powder sphere diameter is between 10 and 70 μm, and it is prepared by spray granulation. Step 4: Spray-coated nanostructured Yb2SiO5, Y2SiO5, Yb2Si2O7 or Y2Si2O7 onto the surface of the zirconate intermediate layer to obtain the silicate top layer. The powder sphere diameter is between 10 and 70 μm, and it is prepared by spray granulation.

6. The method for preparing a nanostructured thermal protective coating for hydrogen fuel cell gas turbines according to claim 5, characterized in that... In steps two through four, the spraying method employs one or more of atmospheric plasma spraying, electron beam physical vapor deposition, supersonic flame spraying, and plasma-physical vapor deposition.

7. The application of the nanostructured thermal protective coating according to any one of claims 1-4 in a hydrogen fuel gas turbine.

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