Multi-layer structure thermal protection coating suitable for hydrogen-containing fuel gas turbine and preparation method of multi-layer structure thermal protection coating

Abstract

The invention discloses a multi-layer structure thermal protection coating suitable for a hydrogen-containing fuel gas turbine and a preparation method of the multi-layer structure thermal protection coating. According to the multi-layer structure thermal protection coating, a high-temperature alloy serves as a base body, and a bonding bottom layer, a YSZ thermal barrier middle layer, a YSZ + silicate functional transition layer and a silicate environment barrier top layer are sequentially sprayed on the surface of the base body. According to the invention, the multi-layer structure thermal protection coating with thermal expansion coefficients in layer-by-layer transition and capable of greatly prolonging the thermal cycle life is constructed by utilizing the change of the structure and components of the multi-layer ceramic coating. The whole coating is provided with a reasonable structure, the premature failure phenomenon caused by thermal mismatch between the double ceramic coatings is effectively relieved, and the thermal cycle life of the thermal protection coating for the hydrogen-containing fuel gas turbine can be effectively prolonged. The multi-layer structure thermal protection coating is easy and convenient to prepare and high in practicability, and tests prove that the multi-layer structure thermal protection coating has the effects of effectively insulating heat, cooling, resisting water and oxygen corrosion and prolonging the service life on the high-temperature alloy for the hydrogen-containing fuel gas turbine.

Description

Technical Field

[0001] The invention relates to a high-temperature thermal protective coating and a preparation method thereof, and in particular to a multi-layered thermal protective coating suitable for a hydrogen-containing fuel gas turbine and a preparation method thereof. Background Art

[0002] As global energy consumption continues to grow, it has not only brought about an energy crisis caused by over-exploitation of non-renewable energy sources such as fossil fuels, but also brought about increasingly urgent problems of climate change and environmental pollution. Hydrogen energy, as a key energy source that can promote the development of a low-carbon economy, has received more and more widespread attention. As the main force of traditional fossil fuel power generation, gas turbines are also actively seeking new development directions in today's increasingly severe situation. Combining hydrogen energy with gas turbines, that is, hydrogen-fueled gas turbines, refers to the premixing and combustion of a certain proportion of hydrogen and natural gas. It can not only achieve clean utilization of energy and improve the power generation efficiency of gas turbines, but also greatly improve the efficiency and flexibility of the energy system, thereby achieving zero carbon emissions in the future and reducing pollution to the environment. Test results of the US DENVER project show that a 5% mass fraction of hydrogen and natural gas mixed fuel can make hydrocarbons, CO2 and NO x Emissions are reduced by 30-50%, and the increase in hydrogen content will also reduce CO2 emissions. Hydrogen-fueled gas turbines have broad development prospects. However, the main materials used in the hot end components of advanced heavy-duty gas turbines currently in service and under development are still high-temperature alloys. Using hydrogen as a partial fuel source will inevitably bring more stringent challenges to the high-temperature alloys of the hot end components: the presence of water vapor, a combustion product of hydrogen, will accelerate the oxidation process of high-temperature alloys; when high-temperature alloys are exposed to a hydrogen environment, hydrogen embrittlement will cause the ductility of alloy materials to decrease, and the strength and mechanical properties of materials to deteriorate; the increase in the proportion of mixed hydrogen will also increase the operating temperature of the combustion chamber and turbine components. The above challenges put forward higher requirements on the performance of high-temperature alloys for gas turbines. However, the development cycle of high-temperature alloys is long and the high-temperature resistance is limited. The increase in turbine inlet temperature, which represents the performance of gas turbines, depends not only on the development of hydrogen fuel technology, but also on the improvement of cooling technology.

[0003] Thermal protection coating technology can be used to cool down high-temperature alloys, isolate the erosion of high-temperature water vapor, and better protect the high-temperature alloy substrate. However, the current high-temperature alloy thermal protection coating is still a typical thermal barrier coating yttrium-stabilized zirconia (YSZ). YSZ will undergo phase changes after long-term service at 1200°C and cannot resist the erosion of high-temperature water vapor. Therefore, it is not suitable for thermal protection materials for hydrogen-fueled gas turbines. Therefore, it is imperative to research and develop new thermal protection coatings suitable for high-temperature alloys that are resistant to high-temperature water vapor corrosion.

[0004] On the basis of comprehensively utilizing the advantages of multiple materials, constructing a thermal protective coating with a multilayer structure is one of the effective methods to improve the performance of the coating. The research and development of silicate materials resistant to high-temperature water and oxygen corrosion is to protect ceramic-based composite materials from environmental factors such as high-temperature water vapor. It has excellent high-temperature water and oxygen corrosion resistance and is the leading candidate material for current environmental barrier coatings. However, silicate materials cannot be directly applied to thermal protective coatings for high-temperature alloys because of the large difference in thermal expansion coefficient between them and the high-temperature alloy substrate. Considering superimposing the silicate coating on the outer layer of the thermal barrier coating YSZ, it can not only take advantage of the advantages of environmental barrier coating materials in terms of water and oxygen corrosion resistance and heat insulation and cooling, but also increase the operating temperature of YSZ, reduce or even prevent YSZ phase transformation. However, the mismatch in thermal expansion coefficients between different materials in the multilayer structure will generate stress during multiple thermal cycles, leading to the initiation of interface cracks, and ultimately leading to the peeling and failure of the coating. Constructing a multilayer thermal protection coating is one of the methods to slow down crack initiation and effectively reduce the negative impact of thermal mismatch. The added functional transition layer can not only ensure the overall strength and corrosion resistance of the thermal protection coating, but also effectively alleviate the rapid change of the thermal expansion coefficient at the silicate / YSZ interface, improve the thermal cycle life, and ensure the structural stability of the coating, thereby increasing the service life of the coating. It can also develop a durable thermal protection coating structure specifically for the special working conditions and use environment of hydrogen-fueled gas turbines. Thermal shock resistance is a key indicator for evaluating the performance of thermal protection coatings. It is directly related to the stability and service life of the coating in a high temperature environment, and is a key factor affecting the durability of the thermal protection system. Summary of the invention

[0005] In order to ensure the structural stability of the multi-layer structure thermal protection coating suitable for hydrogen-fueled gas turbines under high temperature and multiple thermal cycles, the present invention comprehensively utilizes the advantages of material composition and structure for the special working conditions and use environment of hydrogen-fueled gas turbines, and provides a multi-layer structure thermal protection coating suitable for hydrogen-fueled gas turbines and a preparation method thereof. The new structure coating can be used in hydrogen-fueled gas turbines. On the basis of giving full play to the advantages of environmental barrier and thermal barrier coatings, the present invention utilizes the changes in the structure and composition of multi-layer ceramic coatings to construct a multi-layer structure thermal protection coating with a layer-by-layer transition of thermal expansion coefficients that can greatly improve the thermal cycle life. The top layer of the multi-layer structure thermal protection coating of the present invention adopts a silicate coating, and the spraying power is appropriately increased, so that the proportion of the unmelted area of ​​the coating is reduced, the coating density is higher, and the nanohardness is effectively improved. The micropores in the residual unmelted structure can increase the surface energy of the area, so that it has a higher sintering driving force, so that the unmelted area is densified faster, separated from the layer area generated after spraying, and formed relatively large pores, which can offset the negative impact caused by the healing of micropores in the coating during high-temperature service to a certain extent. The transition from the silicate top layer downward to the YSZ+silicate functional transition layer is controlled to be greater than or equal to the silicate ratio. While ensuring a certain resistance to water and oxygen corrosion, the overall thermal cycle performance of the coating is guaranteed. The ratio of YSZ to silicate in the transition layer can be adjusted according to the ratio of hydrogen in the hydrogen-containing fuel, providing targeted resistance to water and oxygen corrosion and mitigation of thermal mismatch. The YSZ intermediate layer, according to the characteristics of the YSZ material that is prone to phase change during service and causes volume change, thereby causing coating failure, appropriately reduces the spraying power, so that the proportion of the unmelted area of ​​the coating increases, the coating porosity is higher, and the thermal conductivity of the coating is effectively reduced. There are a large number of unmelted areas, and the anti-sintering performance during service is significantly improved. The gradient distribution of the composition can make the thermal expansion coefficient of the coating present a gradient change. The composition change occurring along the thickness direction can reduce the thermal expansion mismatch, reduce the residual stress generated by the coating during the shrinkage process, and reduce the internal thermal stress, thereby improving the thermal cycle life. In addition, a bonding bottom layer is set between the ceramic layer and the alloy to alleviate the mismatch between the thermal expansion of the ceramic layer and the metal substrate and improve the bonding strength. The top layer is a silicate environmental barrier coating, the gradient transition layer is a YSZ+silicate functional transition layer, the middle layer is a YSZ thermal barrier layer, plus a bonding bottom layer. Although the entire coating is a multi-layer structure, due to the reasonable composition and structure, the thermal expansion coefficient of the coating presents a gradient change, which effectively alleviates the premature failure caused by thermal mismatch between the double ceramic coatings, and can effectively improve the thermal cycle life of the thermal protective coating for hydrogen-fueled gas turbines. It plays an effective role in heat insulation and cooling, resisting water and oxygen corrosion and extending the service life of high-temperature alloys for hydrogen-fueled gas turbines. It is not only suitable for hydrogen-fueled gas turbines for power generation, but also suitable for hydrogen-fueled gas turbines in navigation, military and other fields.

[0006] The objective of the present invention is achieved through the following technical solutions:

[0007] A multi-layered thermal protective coating suitable for hydrogen-fueled gas turbines, with a high-temperature alloy as the substrate, and a bonding bottom layer, a YSZ thermal barrier middle layer, a YSZ+silicate functional transition layer and a silicate environmental barrier top layer sprayed on the substrate surface in sequence, wherein:

[0008] The high-temperature alloy substrate has a diameter of 25.4 mm and a thickness of 3 to 20 mm, and may be one or more of an iron-based high-temperature alloy, a nickel-based high-temperature alloy, and a cobalt-based high-temperature alloy;

[0009] The material of the bonding bottom layer is MCrAlY, such as one or more of NiCrAlY, CoCrAlY, NiCoCrAlY, with a thickness of 70-110 μm, and is used to improve the thermal compatibility between the ceramic coating and the metal substrate;

[0010] The material of the YSZ thermal barrier intermediate layer is YSZ, with a thickness of 100-150 μm, which is used to reduce the thermal conductivity of the coating and improve phase stability and corrosion resistance;

[0011] The material of the YSZ+silicate functional transition layer is a premix of YSZ and silicate, with a thickness of 30 to 50 μm; the mass proportion of YSZ is 50 to 99%, the structure and composition of YSZ are the same as those of the YSZ thermal barrier intermediate layer, and the structure and composition of silicate are the same as those of the silicate environmental barrier top layer, which are used to alleviate the thermal mismatch caused by the different thermal expansion coefficients of different materials, enhance the bonding strength, and improve the thermal shock resistance of the coating;

[0012] The material of the top layer of the silicate environmental barrier is Yb2SiO5, with a thickness of 30 to 50 μm, and is used on the surface of the thermal protection coating to resist water and oxygen corrosion and to provide heat insulation and cooling.

[0013] The total thickness of the multi-layer thermal protection coating is 230 to 360 μm;

[0014] In the multi-layer structure thermal protection coating, the composition of the silicate environmental barrier top layer to the bonding bottom layer transitions from silicate to YSZ layer by layer, and the thermal expansion coefficient of the coating presents a gradient change;

[0015] In the multi-layer thermal protection coating, the microstructures of the YSZ thermal barrier intermediate layer, the YSZ+silicate functional transition layer and the silicate environmental barrier top layer material are micrometer or nanometer.

[0016] A method for preparing the above-mentioned multi-layer thermal protection coating suitable for hydrogen-containing fuel gas turbines comprises the following steps:

[0017] Step (1) high temperature alloy substrate treatment: cleaning and processing the surface of the substrate to achieve the required roughness for spraying, the specific steps are as follows: processing the surface by fine grinding, ultrasonic cleaning with alcohol or acetone, and then sandblasting or laser processing the surface to improve its roughness, and after reaching the required roughness for spraying, continue ultrasonic cleaning and dry in an oven at 60-90°C for standby use;

[0018] Step (2) spraying the bonding bottom layer: spraying the MCrAlY sprayable feed material on the surface of the substrate to obtain the bonding bottom layer, wherein: the MCrAlY sprayable feed material is a micron-sized powder with a diameter between 15 and 80 μm, and the spraying method adopts one or more of atmospheric plasma spraying (APS), supersonic flame spraying (HVOF), and supersonic flame spraying (HVOF); when supersonic flame spraying (HVOF) is adopted, the preparation parameters of the bonding bottom layer are: N2 is selected as the carrier gas, the carrier gas flow rate is 15 to 20 NLPM, the shielding gas flow rate is 320 to 380 NLPM, the methane flow rate is 160 to 180 NLPM, the powder feeding rate is 25 to 42 g / min, and the spraying distance is 200 to 300 mm;

[0019] Step (3) spraying of YSZ thermal barrier interlayer: spraying a YSZ sprayable feed material on the surface of the bonding base layer to obtain a YSZ thermal barrier interlayer, wherein the YSZ sprayable feed material is a micron-sized powder with a diameter of 15 to 80 μm, and the spraying method is one or more of atmospheric plasma spraying (APS), supersonic flame spraying (HVOF), and supersonic flame spraying (HVOF); when atmospheric plasma spraying (APS) is used, the preparation parameters of the YSZ thermal barrier interlayer are: the spraying current is 550 to 650 A, the voltage is 65 to 80 V, the spraying power is 35 to 52 kW, the main gas is argon, the flow rate is 38 to 42 SCFH, the auxiliary gas is hydrogen, the auxiliary gas flow rate is 10 to 14 SCFH, the powder delivery mode is a turntable, the turntable speed is 35 to 45 r / min, and the carrier gas flow rate is 2 to 3 SCFH;

[0020] Step (4) spraying of YSZ+silicate functional transition layer: premixing the YSZ sprayable feed with the Yb2SiO5 sprayable feed to ensure the uniformity of the sprayable feed mixing, wherein the Yb2SiO5 sprayable feed is a micron-sized powder with a diameter between 15 and 80 μm, and the proportion of YSZ can be arbitrarily changed within a given range of 50 to 99%, and the sum of the two materials is 100%. By regulating the structure and composition of the materials, the thermal shock resistance of the coating is improved; spraying the sprayable feed mixture on the surface of the YSZ thermal barrier intermediate layer to obtain the YSZ+silicate functional transition layer, and the spraying method adopts a large One or more of atmospheric plasma spraying (APS), supersonic flame spraying (HVOF), and supersonic flame spraying (HVOF); when atmospheric plasma spraying (APS) is used, the preparation parameters of the YSZ+silicate functional transition layer are: the spraying current is 400-650A, the voltage is 65-100V, the spraying power is 32-55KW, the main gas is argon, the flow rate is 38-43SCFH, the auxiliary gas is hydrogen, the auxiliary gas flow rate is 10-15SCFH, the powder delivery mode is a turntable, the turntable speed is 20-40r / min, and the carrier gas flow rate is 2-3SCFH;

[0021] Step (5) Spraying of silicate environmental barrier top layer: spraying Yb2SiO5 sprayable feed material on the surface of YSZ+silicate functional transition layer to obtain a single silicate environmental barrier top layer that can resist high temperature water and oxygen corrosion, and then obtaining a multi-layer structure thermal protection coating suitable for hydrogen-containing fuel gas turbines, in which the coating is added with YSZ+silicate functional transition layer to make the coating composition distribution change in a gradient; the spraying method adopts atmospheric plasma spraying (APS), supersonic flame spraying (HVOF), supersonic flame spraying (HVOF), One or more of high volume flame spraying (HVOF); when atmospheric plasma spraying (APS) is used, the preparation parameters of the silicate environmental barrier top layer are: spraying current is 400-550A, voltage is 80-100V, spraying power is 32-55KW, main gas is argon, flow rate is 38-43SCFH, auxiliary gas is hydrogen, auxiliary gas flow rate is 10-15SCFH, powder delivery mode is turntable, turntable speed is 20-40r / min, carrier gas flow rate is 2-3SCFH.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] 1. The present invention is based on the problem that the mismatch in thermal expansion coefficients between different materials in a multi-layer structure will generate stress during multiple thermal cycles, leading to the initiation of interface cracks and ultimately causing the coating to peel off and fail. By comprehensively utilizing the advantages of material composition and structure, a multi-layer thermal protective coating suitable for hydrogen-fueled gas turbines and a preparation method thereof are provided. It has been verified by the embodiments that the thermal cycle life of the multi-layer thermal protective coating at 1100°C can be increased by more than about 60%.

[0024] 2. The present invention, on the basis of giving full play to the advantages of environmental barrier coating materials and thermal barrier coating materials, utilizes the changes in structure and composition to construct a multilayer thermal protection coating with a gradually transitioning thermal expansion coefficient. The proportion of the unmelted area of ​​the top layer of the environmental barrier coating is reduced, and the coating density is higher, which effectively improves the hardness of the coating. The micropores in the residual unmelted structure can increase the surface energy of the area, so that it has a higher sintering driving force, allowing the unmelted area to densify faster and separate from the layer area produced after atmospheric plasma spraying to form relatively large pores, which can offset the negative impact of micropore healing during high-temperature service of the coating to a certain extent. From the top layer of the environmental barrier to the middle layer of the thermal barrier, the proportion of the unmelted area of ​​the coating increases, and the porosity of the coating is slightly higher, which effectively reduces the thermal conductivity of the coating. The large number of unmelted areas significantly improves the anti-sintering performance of the coating during service.

[0025] 3. The gradient change of coating composition distribution can make the thermal expansion coefficient of the coating present a gradient change. The composition change along the thickness direction can reduce the thermal expansion mismatch, reduce the residual stress generated by the coating during the shrinkage process, and reduce the internal thermal stress, thereby increasing the thermal cycle life and thus increasing the service life.

[0026] 4. In the gradient transition layer, the traditional thermal barrier coating material YSZ is combined with the environmental barrier coating material silicate with excellent resistance to environmental corrosion, so that the thermal expansion coefficient of the coating presents a gradient change, the stress change amplitude at the internal crack tip is low, and the crack expansion dynamics are also small, which improves the high-temperature stability of the coating.

[0027] 5. Reasonable spraying parameters are used between each layer. No heat treatment is required after spraying. The top layer of the formed ceramic layer is dense and has few pores. The gradient transition layer alleviates the thermal expansion mismatch. The middle layer has a slightly higher porosity and better thermal insulation effect, and is well bonded with the metal bonding layer. From the base metal to the top ceramic layer, the thermal expansion coefficient gradually transitions, eliminating the internal thermal stress and enhancing the bonding strength, which will help further develop thermal protective coatings for hydrogen-fueled gas turbines. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic structural diagram of a multi-layer thermal protection coating applicable to a hydrogen-fueled gas turbine according to the present invention;

[0029] Figure 2 It is a comparison chart of thermal cycle life of the multilayer structure thermal protection coating prepared in Example 1 and Example 2 and the multilayer structure thermal protection coating prepared in the comparative example;

[0030] Figure 3 This is the SEM image of the multilayer thermal protection coating prepared in Example 1. DETAILED DESCRIPTION

[0031] The technical solution of the present invention is further described below in conjunction with the embodiments, but is not limited thereto. Any modification or equivalent replacement of the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention should be included in the protection scope of the present invention.

[0032] Embodiment 1:

[0033] This embodiment provides a method for preparing a multilayer thermal protection coating suitable for a hydrogen-fueled gas turbine, the method comprising the following steps:

[0034] (1) Use 400-800 mesh SiC sandpaper to finely grind the surface of the GH3230 substrate, use alcohol or acetone ultrasonic cleaning for 10 minutes, and then use SiC sand blasting on the flat and smooth surface to increase its roughness, with a roughness value between 2.00 and 4.00 μm. After reaching the required roughness for spraying, use alcohol ultrasonic cleaning for 5 minutes and dry in a 60°C oven for use.

[0035] (2) A NiCrAlY alloy bonding layer was prepared on the substrate surface treated in step (1) by using a high velocity oxygen flame spraying (HVOF) technique. The preparation parameters of the bonding layer were as follows: N2 was used as carrier gas, the carrier gas flow rate was 15 NLPM, the shielding gas flow rate was 320 NLPM, the methane flow rate was 170 NLPM, the powder feeding rate was 32 g / min, and the spraying distance was 280 mm. The thickness of the NiCrAlY alloy bonding layer obtained after spraying was 105 μm.

[0036] (3) Using atmospheric plasma spraying (APS), spray the YSZ sprayable feed material onto the surface of the bonding base layer prepared in step (2) to obtain the YSZ thermal barrier interlayer in the coating structure. The preparation parameters of the YSZ thermal barrier interlayer are as follows: the spraying current is 650A, the voltage is 72V, the spraying power is 46.8KW, the main gas is argon, the flow rate is 42SCFH, the auxiliary gas is hydrogen, the auxiliary gas flow rate is 12SCFH, the powder feeding mode is a rotary table, the rotary table speed is 35r / min, and the carrier gas flow rate is 2.5SCFH. The thickness of the YSZ thermal barrier interlayer obtained after spraying is 135μm.

[0037] (4) Using atmospheric plasma spraying (APS), the premixed YSZ and Yb2SiO5 sprayable feedstock is sprayed on the surface of the YSZ thermal barrier intermediate layer prepared in step (3) to obtain a YSZ+silicate functional transition layer in the coating structure, wherein the weight ratio of YSZ to Yb2SiO5 is 50:50. The preparation parameters of the YSZ+silicate functional transition layer are as follows: the spraying current is 620A, the voltage is 72V, the spraying power is 44.6KW, the main gas is argon, the flow rate is 38SCFH, the auxiliary gas is hydrogen, the auxiliary gas flow rate is 11.5SCFH, the powder feeding mode is a rotary disk, the rotary disk speed is 32r / min, and the carrier gas flow rate is 3SCFH. The thickness of the YSZ+silicate functional transition layer obtained after spraying is 35μm.

[0038] (5) using atmospheric plasma spraying (APS) to spray Yb2SiO5 sprayable feed material onto the surface of the YSZ+silicate functional transition layer prepared in step (4) to obtain a Yb2SiO5 environmental barrier top layer in the coating structure, thereby obtaining Figure 1 The multilayer thermal protection coating shown in the figure. The preparation parameters of the Yb2SiO5 environmental barrier top layer are: the spraying current is 550A, the voltage is 83V, the spraying power is 45.7KW, the main gas is argon, the flow rate is 38SCFH, the auxiliary gas is hydrogen, the auxiliary gas flow rate is 11.5SCFH, the powder delivery mode is a turntable, the turntable speed is 32r / min, and the carrier gas flow rate is 3SCFH. The thickness of the Yb2SiO5 environmental barrier top layer obtained after spraying is 35μm.

[0039] The SEM image of the multilayer thermal protection coating prepared in this embodiment is as follows: Figure 3 As shown. Figure 3 It can be seen that in the multi-layer thermal protective coating prepared in this embodiment, the thickness and composition of each layer are within the designed range, the layers are well bonded, and there is no obvious interface. The addition of the functional gradient layer can effectively alleviate the drastic changes at the interface, reduce or eliminate the interface stress, avoid or alleviate the cracking of the coating, prevent the coating from failing, and effectively protect the substrate.

[0040] Embodiment 2:

[0041] This embodiment provides a method for preparing a multilayer thermal protection coating suitable for a hydrogen-fueled gas turbine, the method comprising the following steps:

[0042] (1) Use 400-800 mesh SiC sandpaper to finely grind the surface of the GH3230 substrate, use alcohol or acetone ultrasonic cleaning for 10 minutes, and then use SiC sand blasting on the flat and smooth surface to increase its roughness, with a roughness value between 2.00 and 4.00 μm. After reaching the required roughness for spraying, use alcohol ultrasonic cleaning for 5 minutes and dry in a 60°C oven for use.

[0043] (2) A NiCrAlY alloy bonding layer was prepared on the substrate surface treated in step (1) by using a high velocity oxygen flame spraying (HVOF) technique. The preparation parameters of the bonding layer were as follows: N2 was used as carrier gas, the carrier gas flow rate was 15 NLPM, the shielding gas flow rate was 320 NLPM, the methane flow rate was 170 NLPM, the powder feeding rate was 32 g / min, and the spraying distance was 280 mm. The thickness of the NiCrAlY alloy bonding layer obtained after spraying was 105 μm.

[0044] (3) Using atmospheric plasma spraying (APS), spray the YSZ sprayable feed material onto the surface of the bonding base layer prepared in step (2) to obtain the YSZ thermal barrier interlayer in the coating structure. The preparation parameters of the YSZ thermal barrier interlayer are as follows: the spraying current is 650A, the voltage is 80V, the spraying power is 52KW, the main gas is argon, the flow rate is 42SCFH, the auxiliary gas is hydrogen, the auxiliary gas flow rate is 12SCFH, the powder feeding mode is a turntable, the turntable speed is 35r / min, and the carrier gas flow rate is 2.5SCFH. The thickness of the YSZ thermal barrier interlayer obtained after spraying is 135μm.

[0045] (4) Using atmospheric plasma spraying (APS), the premixed YSZ and Yb2SiO5 sprayable feedstock is sprayed on the surface of the YSZ thermal barrier intermediate layer prepared in step (3) to obtain a YSZ+silicate functional transition layer in the coating structure, wherein the weight ratio of YSZ to Yb2SiO5 is 70:30. The preparation parameters of the YSZ+silicate functional transition layer are as follows: the spraying current is 630A, the voltage is 75V, the spraying power is 47.3KW, the main gas is argon, the flow rate is 38SCFH, the auxiliary gas is hydrogen, the auxiliary gas flow rate is 11.5SCFH, the powder feeding mode is a turntable, the turntable speed is 32r / min, and the carrier gas flow rate is 3SCFH. The thickness of the YSZ+silicate functional transition layer obtained after spraying is 35μm.

[0046] (5) using atmospheric plasma spraying (APS) to spray Yb2SiO5 sprayable feed material onto the surface of the YSZ+silicate functional transition layer prepared in step (4) to obtain a Yb2SiO5 environmental barrier top layer in the coating structure, thereby obtaining Figure 1 The multilayer thermal protection coating shown in the figure. The preparation parameters of the Yb2SiO5 environmental barrier top layer are: the spraying current is 500A, the voltage is 90V, the spraying power is 45KW, the main gas is argon, the flow rate is 38SCFH, the auxiliary gas is hydrogen, the auxiliary gas flow rate is 11.5SCFH, the powder delivery mode is a turntable, the turntable speed is 32r / min, and the carrier gas flow rate is 3SCFH. The thickness of the Yb2SiO5 environmental barrier top layer obtained after spraying is 35μm.

[0047] Embodiment 3:

[0048] This embodiment provides a method for preparing a multilayer thermal protection coating suitable for a hydrogen-fueled gas turbine, the method comprising the following steps:

[0049] (1) Use 400-800 mesh SiC sandpaper to finely grind the surface of the GH3230 substrate, use alcohol or acetone ultrasonic cleaning for 10 minutes, and then use SiC sand blasting on the flat and smooth surface to increase its roughness, with a roughness value between 2.00 and 4.00 μm. After reaching the required roughness for spraying, use alcohol ultrasonic cleaning for 5 minutes and dry in a 60°C oven for use.

[0050] (2) A NiCoCrAlY alloy bonding layer was prepared on the substrate surface treated in step (1) by using a high velocity oxygen flame spraying (HVOF) technique. The preparation parameters of the bonding layer were as follows: N2 was used as carrier gas, the carrier gas flow rate was 15 NLPM, the shielding gas flow rate was 320 NLPM, the methane flow rate was 170 NLPM, the powder feeding rate was 32 g / min, and the spraying distance was 280 mm. The thickness of the NiCrAlY alloy bonding layer obtained after spraying was 85 μm.

[0051] (3) Using atmospheric plasma spraying (APS), spray the YSZ sprayable feed material onto the surface of the bonding base layer prepared in step (2) to obtain the YSZ thermal barrier interlayer in the coating structure. The preparation parameters of the YSZ thermal barrier interlayer are as follows: the spraying current is 650A, the voltage is 80V, the spraying power is 52KW, the main gas is argon, the flow rate is 42SCFH, the auxiliary gas is hydrogen, the auxiliary gas flow rate is 12SCFH, the powder feeding mode is a rotary table, the rotary table speed is 35r / min, and the carrier gas flow rate is 2.5SCFH. The thickness of the YSZ thermal barrier interlayer obtained after spraying is 115μm.

[0052] (4) Using atmospheric plasma spraying (APS), the premixed YSZ and Yb2SiO5 sprayable feedstock is sprayed on the surface of the YSZ thermal barrier intermediate layer prepared in step (3) to obtain a YSZ+silicate functional transition layer in the coating structure, wherein the weight ratio of YSZ to Yb2SiO5 is 90:10. The preparation parameters of the YSZ+silicate functional transition layer are: the spraying current is 610A, the voltage is 75V, the spraying power is 45.8KW, the main gas is argon, the flow rate is 38SCFH, the auxiliary gas is hydrogen, the auxiliary gas flow rate is 11.5SCFH, the powder feeding mode is a turntable, the turntable speed is 34r / min, and the carrier gas flow rate is 3SCFH. The thickness of the YSZ+silicate functional transition layer obtained after spraying is 40μm.

[0053] (5) using atmospheric plasma spraying (APS) to spray Yb2SiO5 sprayable feed material onto the surface of the YSZ+silicate functional transition layer prepared in step (4) to obtain a Yb2SiO5 environmental barrier top layer in the coating structure, thereby obtaining Figure 1 The multilayer thermal protection coating is shown. The preparation parameters of the Yb2SiO5 environmental barrier top layer are: the spraying current is 530A, the voltage is 85V, the spraying power is 45KW, the main gas is argon, the flow rate is 38SCFH, the auxiliary gas is hydrogen, the auxiliary gas flow rate is 11.5SCFH, the powder delivery mode is a turntable, the turntable speed is 32r / min, and the carrier gas flow rate is 3SCFH. The thickness of the Yb2SiO5 environmental barrier top layer obtained after spraying is 45μm.

[0054] Comparative Example:

[0055] This comparative example provides a multilayer thermal protection coating suitable for a hydrogen-fueled gas turbine and a preparation method thereof, the method comprising the following steps:

[0056] (1) Use 400-800 mesh SiC sandpaper to finely grind the surface of the GH3230 substrate, use alcohol or acetone ultrasonic cleaning for 10 minutes, and then use SiC sand blasting on the flat and smooth surface to increase its roughness, with a roughness value between 2.00 and 4.00 μm. After reaching the required roughness for spraying, use alcohol ultrasonic cleaning for 5 minutes and dry in a 60°C oven for use.

[0057] (2) A NiCrAlY alloy bonding layer was prepared on the substrate surface treated in step (1) by using a high velocity oxygen flame spraying (HVOF) technique. The preparation parameters of the bonding layer were as follows: N2 was used as carrier gas, the carrier gas flow rate was 15 NLPM, the shielding gas flow rate was 320 NLPM, the methane flow rate was 170 NLPM, the powder feeding rate was 32 g / min, and the spraying distance was 280 mm. The thickness of the NiCrAlY alloy bonding layer obtained after spraying was 105 μm.

[0058] (3) Using atmospheric plasma spraying (APS), spray the YSZ sprayable feed material onto the surface of the bonding base layer prepared in step (2) to obtain the YSZ thermal barrier interlayer in the coating structure. The preparation parameters of the YSZ thermal barrier interlayer are as follows: the spraying current is 650A, the voltage is 75V, the spraying power is 48.7KW, the main gas is argon, the flow rate is 42SCFH, the auxiliary gas is hydrogen, the auxiliary gas flow rate is 12SCFH, the powder feeding mode is a rotary table, the rotary table speed is 35r / min, and the carrier gas flow rate is 2.5SCFH. The thickness of the YSZ thermal barrier interlayer obtained after spraying is 135μm.

[0059] (4) Using atmospheric plasma spraying (APS), spray Yb2SiO5 sprayable feed material onto the surface of the YSZ thermal barrier intermediate layer prepared in step (3) to obtain the Yb2SiO5 environmental barrier top layer in the coating structure. The preparation parameters of the Yb2SiO5 environmental barrier top layer are as follows: the spraying current is 550A, the voltage is 78V, the spraying power is 42.9KW, the main gas is argon, the flow rate is 38SCFH, the auxiliary gas is hydrogen, the auxiliary gas flow rate is 11.5SCFH, the powder delivery mode is a rotary disk, the rotary disk speed is 32r / min, and the carrier gas flow rate is 3SCFH. The thickness of the Yb2SiO5 environmental barrier top layer obtained after spraying is 70μm.

[0060] Thermal cycle performance test:

[0061] The coating thermal cycle test conditions are: the sample is kept at 1100℃ for 5 minutes, and then the sample is quickly taken out and placed in deionized water at room temperature (~25℃). After cooling to room temperature, it is blown dry with compressed air. A thermal cycle process includes a heating, a heat preservation and a cooling process. Repeat the above process until the coating peeling area reaches 20%, which is considered to be a failure.

[0062] Figure 2 is a comparison chart of thermal cycle life of Examples 1 and 2 and the comparative example, Figure 2 It can be seen that the thermal cycle resistance of the multi-layer thermal protection coating prepared by the present invention is increased by more than about 60%.

Claims

1. A multi-layer thermal protection coating suitable for hydrogen-fueled gas turbines, characterized in that The multi-layer thermal protective coating takes a high-temperature alloy as a substrate, and a bonding base layer, a YSZ thermal barrier middle layer, a YSZ+silicate functional transition layer and a silicate environmental barrier top layer are sprayed on the surface of the substrate in sequence. The material of the YSZ+silicate functional transition layer is a premix of YSZ and silicate, wherein the mass proportion of YSZ is 50-99%, the structure and composition of YSZ are the same as those of the material used for the YSZ thermal barrier middle layer, and the structure and composition of silicate are the same as those of the material used for the silicate environmental barrier top layer.

2. The multi-layer thermal protection coating suitable for hydrogen-fueled gas turbine according to claim 1, characterized in that The high-temperature alloy substrate has a diameter of 25.4 mm and a thickness of 3 to 20 mm, and is one or more of an iron-based high-temperature alloy, a nickel-based high-temperature alloy, and a cobalt-based high-temperature alloy.

3. The multi-layer thermal protection coating suitable for hydrogen-fueled gas turbine according to claim 1, characterized in that The total thickness of the multi-layer thermal protection coating is 230-360 μm, the thickness of the bonding bottom layer is 70-110 μm, the thickness of the YSZ thermal barrier middle layer is 100-150 μm, the thickness of the YSZ+silicate functional transition layer is 30-50 μm, and the thickness of the silicate environmental barrier top layer is 30-50 μm.

4. The multi-layer thermal protection coating suitable for hydrogen-fueled gas turbine according to claim 1 or 3, characterized in that The material of the bonding bottom layer is MCrAlY.

5. The multi-layer thermal protection coating suitable for hydrogen-fueled gas turbine according to claim 4, characterized in that The material of the bonding bottom layer is one or more of NiCrAlY, CoCrAlY, and NiCoCrAlY.

6. The multi-layer thermal protection coating suitable for hydrogen-fueled gas turbine according to claim 1 or 3, characterized in that The material of the YSZ thermal barrier interlayer is YSZ.

7. The multi-layer thermal protection coating suitable for hydrogen-fueled gas turbine according to claim 1 or 3, characterized in that The material of the top layer of the silicate environmental barrier is Yb2SiO5.

8. A method for preparing a multilayer thermal protective coating suitable for a hydrogen-fueled gas turbine according to any one of claims 1 to 7, characterized in that The method comprises the following steps: Step (1) high temperature alloy substrate treatment: cleaning and processing the surface of the substrate to achieve the required roughness for spraying; Step (2) spraying the bonding bottom layer: spraying the MCrAlY sprayable feed material on the surface of the substrate to obtain the bonding bottom layer; Step (3) spraying a YSZ thermal barrier interlayer: spraying a YSZ sprayable feed material on the surface of the bonding base layer to obtain a YSZ thermal barrier interlayer; Step (4) spraying of YSZ+silicate functional transition layer: premixing a YSZ sprayable feed material with a Yb2SiO5 sprayable feed material, and spraying the sprayable feed material mixture on the surface of the YSZ thermal barrier intermediate layer to obtain a YSZ+silicate functional transition layer; Step (5) Spraying of silicate environmental barrier top layer: spraying Yb2SiO5 sprayable feed material on the surface of YSZ+silicate functional transition layer to obtain silicate environmental barrier top layer, and then obtaining a multi-layer structure thermal protection coating.

9. The method for preparing a multilayer thermal protection coating suitable for a hydrogen-fueled gas turbine according to claim 8, characterized in that The MCrAlY sprayable feed material is a micron-sized powder; the YSZ sprayable feed material is a micron-sized powder; the Yb2SiO5 sprayable feed material is a micron-sized powder; the spraying methods all adopt one or more of atmospheric plasma spraying, supersonic flame spraying, and supersonic flame spraying.

10. Use of the multi-layer thermal protection coating according to any one of claims 1 to 7 in a hydrogen-fueled gas turbine.

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