Thermal barrier coating, preparation method thereof and high-temperature-resistant component

Abstract

In order to solve the problem that an existing thermal barrier coating is insufficient in thermal shock resistance and sintering resistance, the thermal barrier coating comprises a thermal insulation bottom layer and a high strain tolerance layer, the thermal insulation bottom layer is located on the lower layer of the high strain tolerance layer, the thermal insulation bottom layer comprises lamellar yttrium-stabilized zirconium oxide with lamellar units stacked, and the lamellar yttrium-stabilized zirconium oxide is located on the lower layer of the high strain tolerance layer. The high strain tolerance layer comprises high strain tolerance yttrium-stabilized zirconium oxide, and the high strain tolerance yttrium-stabilized zirconium oxide has one or more of a vertical crack structure, a columnar structure and a porous structure. Meanwhile, the invention further discloses a preparation method of the thermal barrier coating and a high-temperature-resistant component. According to the thermal barrier coating provided by the invention, the thermal shock resistance and the sintering resistance of the coating can be remarkably improved while the good thermal insulation performance is maintained.

Description

Technical Field

[0001] The present invention belongs to the technical field of high-temperature protective coatings, and in particular relates to a thermal barrier coating and a preparation method thereof, and a high-temperature resistant component. Background Art

[0002] Small and medium-sized gas turbines have significant advantages and broad application prospects in the field of power peak regulation due to their advantages of fast start and stop and convenient maintenance compared to other large-scale power generation equipment. Due to the volatility and randomness of the power grid load, the power grid is often overloaded during peak power consumption. At this time, it is necessary to invest in generator sets outside normal operation to meet the demand. These generator sets are called peak-shaving units. The basic requirements of peak-shaving units are fast start and stop speed and high frequency, so as to meet the synchronous adjustment requirements when connected to the grid. This means that peak-shaving gas turbines need to be started and stopped frequently, which poses a severe challenge to the thermal shock resistance of the thermal barrier coating of the gas turbine.

[0003] Among the hot end parts of gas turbines, turbine blades are listed as the first key parts because they are located in key positions with high operating temperature, complex stress and harsh environment. Among them, the first-stage guide vanes are located at the outlet of the combustion chamber, playing an important role in guiding the high-temperature gas generated in the combustion chamber and optimizing the flow direction and speed of the gas, and the demand for thermal barrier coatings is the most urgent.

[0004] Thermal barrier coating (TBC) is a high-temperature structural material surface protection technology that utilizes the excellent high-temperature resistance, heat insulation and corrosion resistance of ceramic materials to composite ceramics with metal substrates in the form of coatings. It is usually composed of a ceramic surface layer with low thermal conductivity and a metal bonding layer. Studies have shown that after a 150μm thick thermal barrier coating is prepared on the surface of a first-stage turbine blade, the operating temperature of the blade's high-temperature alloy surface can be reduced by more than 50°C, and the blade's service life can be increased by more than 3 times, while also improving work efficiency and reducing emissions.

[0005] YSZ (yttrium-stabilized zirconia) is often used as the main material for thermal barrier coatings due to its high thermal stability and low thermal conductivity. There are many ways to prepare YSZ layers. The most common one is the APS process (atmospheric plasma spraying), which can form a lamellar structure with good thermal insulation performance. However, this type of APS YSZ has the problem of insufficient thermal shock resistance. Under long-term thermal shock, the coating is prone to fall off. In addition, APS YSZ has insufficient anti-sintering performance and is prone to adhesion under high temperature conditions, which affects the thermal insulation performance of the thermal barrier coating and ultimately affects the protection of the turbine blades. Summary of the invention

[0006] In view of the problem that existing thermal barrier coatings have insufficient thermal shock resistance and sintering resistance, the present invention provides a thermal barrier coating and a preparation method thereof, and a high-temperature resistant component.

[0007] The technical solution adopted by the present invention to solve the above technical problems is as follows: On the one hand, the present invention provides a thermal barrier coating, comprising a thermal insulation base layer and a high strain tolerance layer, wherein the thermal insulation base layer is located below the high strain tolerance layer, the thermal insulation base layer comprises a lamellar yttrium-stabilized zirconia having lamellar units stacked together, and the high strain tolerance layer comprises a high strain tolerance yttrium-stabilized zirconia, wherein the high strain tolerance yttrium-stabilized zirconia has one or more of a vertical crack structure, a columnar structure, and a porous structure.

[0008] Optionally, the thickness of the thermal insulation bottom layer is 50-500 μm. In the thermal insulation bottom layer, the transverse major axis of the sheet unit is 5-30 μm, and the longitudinal thickness is 2-10 μm.

[0009] Optionally, the porosity of the thermal insulation bottom layer is 5% to 25%.

[0010] Optionally, the thickness of the high strain tolerance layer is 60-300 μm.

[0011] Optionally, the vertical crack structure includes a plurality of cracks extending along the thickness direction of the high strain tolerance layer, the cracks have a depth of 60-300 μm, a width of 0.3-3 μm, and a density of 2-10 mm -1 ; The columnar structure includes a plurality of columnar microstructures extending along the thickness direction of the high strain tolerance layer, the height of the columnar microstructure is 60-300 μm, and the density is 5-30 mm -1 ; The porous structure includes a plurality of micropores formed inside the high strain tolerance layer, the pore diameter of the micropores is 0.5-5 μm, and the porosity of the porous structure is 25%-45%.

[0012] Optionally, a bonding layer is further included, the bonding layer is located on a side of the thermal insulation bottom layer away from the high strain tolerance layer, the bonding layer includes at least one of MCrAlY and MCrAlTaY, wherein M is Ni and / or Co, The thickness of the bonding layer is 50-200 μm.

[0013] On the other hand, the present invention provides a high-temperature resistant component, including a hot end component and the thermal barrier coating as described above, wherein the thermal barrier coating is arranged on the surface of the hot end component, and the hot end component includes a turbine blade, a combustion chamber, a heat shield, a nozzle, a flame tube or a tail nozzle.

[0014] In another aspect, the present invention provides a method for preparing the thermal barrier coating as described above, comprising the following steps: Yttrium-stabilized zirconia powder is used as a raw material for atmospheric plasma spraying to form a layer of yttrium-stabilized zirconia with layered units to obtain a heat-insulating bottom layer; A high strain tolerance layer is formed on the surface of the thermal insulation base layer by using atomized suspension plasma spraying of yttrium stabilized zirconia suspension.

[0015] Optionally, also include: MCrAlY and / or MCrAlTaY are used as raw materials for hypersonic flame spraying, wherein M is Ni and / or Co, to prepare a bonding layer on the hot end component, and the spraying parameters are: kerosene 25-30L / h, oxygen 800-900L / h, and spray distance 300-350mm.

[0016] Optionally, the parameters of the atmospheric plasma spraying are: ion spraying current is 450-500A, spraying distance is 110-120mm; spray gun swing rate is 500-600mm / s; Ar gas flow rate is 30-35slpm; H2 flow rate is 6-8slpm, The atomized suspension plasma spraying adopts radial atomized suspension plasma spraying, and the parameters are: plasma spraying current is 600-650A; spraying distance is 60-95mm; Ar gas flow rate is 30-70slpm; H2 flow rate is 10-12slpm; suspension solid content is 18-30%; suspension feeding rate is 20-35ml / min; atomization pressure is 0.04-0.05MPa.

[0017] According to the thermal barrier coating provided by the present invention, a lamellar yttrium-stabilized zirconia is used as a thermal insulation bottom layer, wherein the lamellar yttrium-stabilized zirconia has a lamellar unit stacking structure, and the interlayer gap formed by the lamellar yttrium-stabilized zirconia can effectively reduce the longitudinal thermal conductivity, thereby effectively blocking the heat conduction of the environmental high temperature to the hot end components; in view of the problem that the lamellar yttrium-stabilized zirconia has insufficient thermal shock resistance and sintering resistance, a high strain tolerance yttrium-stabilized zirconia is applied on the surface of the lamellar yttrium-stabilized zirconia as a high strain tolerance layer, and the high strain tolerance yttrium-stabilized zirconia has one or more of a vertical crack structure, a columnar structure and a porous structure, and the high strain tolerance of the structure Variable-tolerance yttrium-stabilized zirconia has good anti-sintering performance, and can reduce the thermal mismatch stress of the surface layer under the action of thermal shock, thereby avoiding premature peeling and failure of the surface layer. Correspondingly, the presence of the lamellar yttrium-stabilized zirconia is also beneficial to further improve the thermal shock resistance of the high strain tolerance yttrium-stabilized zirconia. Therefore, compared with a single lamellar yttrium-stabilized zirconia or a single high strain tolerance yttrium-stabilized zirconia, the composite structure formed by the lamellar yttrium-stabilized zirconia and the high strain tolerance yttrium-stabilized zirconia exhibits a better synergistic effect, and can significantly improve the thermal shock resistance and sintering resistance of the coating while maintaining good thermal insulation performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic diagram of the structure of the thermal barrier coating provided by the present invention; Figure 2 This is the SEM cross-sectional morphology of the thermal barrier coating system obtained in Example 1; Figure 3 This is the high-magnification SEM cross-sectional morphology of the thermal barrier coating system obtained in Example 1; Figure 4 This is the SEM cross-sectional morphology of the thermal barrier coating system obtained in Example 2; Figure 5 This is the metallographic cross-sectional morphology of the thermal barrier coating at the air inlet edge of the blade obtained in Example 3; Figure 6 This is the SEM cross-sectional morphology of the thermal barrier coating system obtained in Comparative Example 1; Figure 7 This is the SEM cross-sectional morphology of the thermal barrier coating system obtained in Comparative Example 2; Figure 8 This is the SEM cross-sectional morphology of the thermal barrier coating system obtained in Comparative Example 3; Fig. 9 Schematic diagram of radial atomization suspension plasma spraying process parameter space.

[0019] The reference numerals in the drawings of the specification are as follows: 1. High strain tolerance layer; 2. Thermal insulation base layer; 3. Adhesive layer; 4. Hot end components. DETAILED DESCRIPTION

[0020] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0021] In the description of the present invention, when a layer is described as being "on" or "over" another layer or substrate, it should be understood that unless explicitly stated to the contrary, the layers may be directly in contact with each other or have another layer or feature between the layers. Therefore, these terms simply describe the relative position of the layers to each other and do not necessarily mean "above", as the relative position of above or below depends on the orientation of the device relative to the viewer.

[0022] See also Figure 1As shown, an embodiment of the present invention provides a thermal barrier coating, including a thermal insulation bottom layer 2 and a high strain tolerance layer 1, wherein the thermal insulation bottom layer 2 is located under the high strain tolerance layer 1, and the thermal insulation bottom layer 2 includes a lamellar yttrium-stabilized zirconia with lamellar units stacked, and the high strain tolerance layer 1 includes a high strain tolerance yttrium-stabilized zirconia, and the high strain tolerance yttrium-stabilized zirconia has one or more of a vertical crack structure, a columnar structure, and a porous structure.

[0023] Among them, the lamellar yttrium-stabilized zirconia has a lamellar unit stacking structure, and the interlayer gap formed by it can effectively reduce the longitudinal thermal conductivity, thereby effectively blocking the heat conduction of the high temperature environment to the hot end component 4; in view of the problem that the lamellar yttrium-stabilized zirconia has insufficient thermal shock resistance and sintering resistance, a high strain tolerance yttrium-stabilized zirconia is applied on the surface of the lamellar yttrium-stabilized zirconia as a high strain tolerance layer 1, and the high strain tolerance yttrium-stabilized zirconia has one or more of a vertical crack structure, a columnar structure and a porous structure. The high strain tolerance yttrium-stabilized zirconia of this structure has good The present invention has anti-sintering performance, and can reduce the thermal mismatch stress of the surface layer under the action of thermal shock, thereby avoiding premature peeling and failure of the surface layer. Correspondingly, the presence of the lamellar yttrium-stabilized zirconia is also beneficial to further improve the thermal shock resistance of the high strain tolerance yttrium-stabilized zirconia. Therefore, compared with a single lamellar yttrium-stabilized zirconia or a single high strain tolerance yttrium-stabilized zirconia, the composite structure formed by the lamellar yttrium-stabilized zirconia and the high strain tolerance yttrium-stabilized zirconia exhibits better synergistic effect, while maintaining better thermal insulation performance, it can significantly improve the thermal shock resistance and sintering resistance of the coating.

[0024] In some embodiments, the thickness of the thermal insulation bottom layer 2 is 50-500 μm.

[0025] In a preferred embodiment, the thickness of the thermal insulation bottom layer 2 is 150-200 μm. Specifically, the thickness of the thermal insulation bottom layer 2 can be 150 μm, 160 μm, 170 μm, 180 μm, 190 μm, 200 μm or any range therebetween.

[0026] The lamellar yttrium-stabilized zirconia in the thermal insulation bottom layer 2 can be prepared by atmospheric plasma spraying, has a lamellar structure, and has a low thermal conductivity. When the thickness of the thermal insulation bottom layer 2 is too low, it is not conducive to the high-temperature protection of the hot end component 4; when the thickness of the thermal insulation bottom layer 2 is too high, it increases the risk of it falling off under thermal shock conditions.

[0027] In some embodiments, in the thermal insulation bottom layer 2, the transverse major axis of the sheet unit is 5-30 μm, and the longitudinal thickness is 2-10 μm.

[0028] In some embodiments, the porosity of the thermal insulation bottom layer 2 is 5% to 25%.

[0029] Porosity is an important characteristic of lamellar yttrium-stabilized zirconia. When the porosity of the thermal insulation bottom layer 2 is within the above range, it is beneficial to reduce thermal conductivity and improve thermal insulation performance.

[0030] In some embodiments, the high strain tolerance layer 1 has a thickness of 60-300 μm.

[0031] In a preferred embodiment, the thickness of the high strain tolerance layer 1 is 100-150 μm. Specifically, the thickness of the high strain tolerance layer 1 may be 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm or any range therebetween.

[0032] The high strain tolerance yttrium stabilized zirconia can provide high strain tolerance, so that the thermal barrier coating can better cope with the impact of thermal stress during thermal shock, and is not prone to vertical cracks and other structures, thereby reducing the risk of premature peeling and improving thermal shock life. If the thickness of the high strain tolerance layer 1 is too low, it is difficult to better cope with the stress caused by thermal shock, and it is easy to expose the thermal insulation bottom layer 2 under long-term hot air flow shock, thereby causing the thermal barrier coating to fall off.

[0033] The high strain tolerance layer 1 is prepared by atomized suspension plasma spraying. By adjusting the spraying process parameters, a high strain tolerance yttrium-stabilized zirconia having a vertical crack structure, a columnar structure, a porous structure or a combination of these structures can be formed.

[0034] In some embodiments, the vertical crack structure includes a plurality of cracks extending along the thickness direction of the high strain tolerance layer 1, the crack depth is 60-300 μm, the width is 0.3-3 μm, and the density is 2-10 mm -1 .

[0035] When the high strain tolerance layer 1 includes the vertical crack structure, it generally has a relatively dense structure. In some cases, the vertical crack structure has micropores at non-crack positions. The presence of cracks in the vertical crack structure enables the high strain tolerance layer 1 to have high strain tolerance. It can be considered that during the thermal shock process, the cracks can adapt to the thermal expansion strain generated by the high strain tolerance layer 1 to avoid the formation of internal stress during the thermal shock process, which may cause the high strain tolerance layer 1 to fall off. In the high strain tolerance layer 1, adjacent cracks may be interconnected or independent of each other.

[0036] In some embodiments, the columnar structure includes a plurality of columnar microstructures extending along the thickness direction of the high strain tolerance layer 1, wherein the height of the columnar microstructure is 60-300 μm and the density is 5-30 mm -1 .

[0037] The columnar structure is another structure with high strain tolerance different from the vertical crack structure, and is characterized by having a plurality of columnar microstructures extending along the thickness direction of the high strain tolerance layer 1. The columnar microstructures may be feather columnar structures or other columnar structures. Adjacent columnar microstructures exhibit obvious directional arrangement characteristics, and the crystals are not completely fitted together, and gaps are retained to achieve their high strain tolerance. When the high strain tolerance layer 1 includes the columnar structure, it may also include a porous structure as described below.

[0038] In some embodiments, the porous structure includes a plurality of micropores formed inside the high strain tolerance layer 1 , the pore diameter of the micropores is 0.5-5 μm, and the porosity of the porous structure is 25%-45%.

[0039] The porous structure usually appears with a vertical crack structure and a columnar structure, but under certain conditions (by adjusting the atomized suspension plasma spraying parameters), a high strain tolerance layer 1 having a porous structure alone can also be achieved, and the micropores inside the porous structure have the effect of improving the overall thermal insulation performance of the high strain tolerance layer 1.

[0040] In some embodiments, the thermal barrier coating further includes a bonding layer 3, wherein the bonding layer 3 is located on a side of the thermal insulation base layer 2 away from the high strain tolerance layer 1, and the bonding layer 3 includes at least one of MCrAlY and MCrAlTaY, wherein M is Ni and / or Co.

[0041] The bonding layer 3 is used to improve the bonding strength between the thermal insulation bottom layer 2 and the surface of the hot end component 4. When the bonding layer 3 is selected from MCrAlY and / or MCrAlTaY, it has good compatibility with both the hot end component 4 and the thermal insulation bottom layer 2, thereby improving the bonding performance of the thermal barrier coating.

[0042] In some embodiments, the thickness of the adhesive layer 3 is 50-200 μm.

[0043] Another embodiment of the present invention provides a high temperature resistant component, comprising a hot end component 4 and the thermal barrier coating as described above, wherein the thermal barrier coating is disposed on the surface of the hot end component 4 .

[0044] The thermal barrier coating can significantly improve the thermal shock resistance and sintering resistance of the coating while maintaining good thermal insulation performance; by applying the thermal barrier coating to the surface of the hot end component 4, it is beneficial to improve the thermal shock resistance and high-temperature service life of the hot end component 4.

[0045] In some embodiments, the hot end component 4 includes a turbine blade, a combustion chamber, a heat shield, a nozzle, a flame tube or a tail nozzle.

[0046] Exemplary applications of the hot end component 4 include turbine components, specifically, those components located in the combustion section (e.g., combustor, liner and / or heat shield), or turbine sections (e.g., turbine blades, blades and / or shrouds). Application scenarios of the turbine components include high bypass turbofan jet engines, turbojet engines, turboprop engines or turboshaft gas turbine engines, as well as industrial and marine gas turbine engines and auxiliary power units.

[0047] In one embodiment, the hot end component 4 is selected from a turbine guide blade, and the turbine guide blade includes a blade body, an upper rafter plate and a lower rafter plate, and the blade body is divided into four parts: a blade back, a blade basin, an air inlet edge, and an exhaust edge.

[0048] Another embodiment of the present invention provides a method for preparing the thermal barrier coating as described above, comprising the following steps: Yttrium-stabilized zirconia powder is used as a raw material for atmospheric plasma spraying to form a layer of yttrium-stabilized zirconia with layered units to obtain a heat-insulating bottom layer; A high strain tolerance layer is formed on the surface of the thermal insulation base layer by using atomized suspension plasma spraying of yttrium stabilized zirconia suspension.

[0049] This application proposes a composite thermal barrier coating system with a thermal insulation base layer of yttrium-stabilized zirconia and a high strain tolerance layer with various structures, as well as a coating preparation and control method based on plasma spraying equipment. Compared with the APS coating technology widely used in the preparation of thermal barrier coatings for gas turbine blades, the cost is basically the same. According to the actual needs of the hot end components of the gas turbine, the required high strain tolerance structure thermal barrier coating can be obtained at low cost, so that the thermal barrier coating has excellent thermal insulation performance, high thermal shock life, high sintering resistance and other excellent properties. At the same time, the preparation method provided by this application is particularly suitable for the surface thermal barrier coating of hot end components with three-dimensional surfaces such as turbine guide blades, and can form a high strain tolerance layer and thermal insulation base layer with relatively uniform thickness.

[0050] In some embodiments, the preparation method further comprises: MCrAlY and / or MCrAlTaY are used as raw materials for hypersonic flame spraying, wherein M is Ni and / or Co, to prepare a bonding layer on the hot end component, and the spraying parameters are: kerosene 25-30L / h, oxygen 800-900L / h, and spray distance 300-350mm.

[0051] In some embodiments, the parameters of the atmospheric plasma spraying are: ion spraying current is 450-500A, spraying distance is 110-120mm; spray gun swing rate is 500-600mm / s; Ar gas flow rate is 30-35slpm; H2 flow rate is 6-8slpm.

[0052] The suspension plasma spraying is a new type of thermal spraying technology for preparing thermal barrier coatings with advanced structures. By feeding the thermal barrier coating powder material into the plasma flame in the form of a suspension, the problem of easy agglomeration and insufficient fluidity of nano and submicron powders is fundamentally solved. Therefore, the unique flight characteristics of nano and submicron powder materials in the plasma flame can be used to prepare thermal barrier coatings with high strain tolerance structures such as vertical cracks and columnar structures, and a high porosity can be maintained to reduce the thermal conductivity of the coating, overcoming the problem of insufficient thermal insulation performance of the dense vertical crack structure thermal barrier coating prepared by APS and the columnar structure thermal barrier coating prepared by EB-PVD.

[0053] In the suspension plasma spraying operation, there are two types of suspension feeding methods, namely axial feeding and radial feeding. For the radial feeding method, due to the limitations of feeding methods and power, the spraying distance is usually required to be shorter, generally controlled within the range of 40~60mm, but radial external feeding has a wide range of equipment applications and low production costs, which is more in line with the needs of producing thermal barrier coatings for small and medium-sized gas turbines; while the axial feeding method based on multi-electrode plasma spraying equipment has a larger spray distance (>60mm) and a wider process window, but the cost is high and is not suitable for the engineering application of thermal barrier coatings for small and medium-sized gas turbine blades.

[0054] In some embodiments, the atomized suspension plasma spraying adopts radial atomized suspension plasma spraying, and the parameters are: plasma spraying current is 600-650A; spraying distance is 60-95mm; Ar gas flow rate is 30-70slpm; H2 flow rate is 10-12slpm; suspension solid content is 18-30%; suspension feeding rate is 20-35ml / min; atomization pressure is 0.04-0.05MPa.

[0055] The method for controlling the morphology of the high strain tolerance layer is based on the control of radial atomization suspension plasma spraying process parameters, wherein the spraying distance and Ar gas flow rate are important factors affecting the morphology of the high strain tolerance layer, such as Fig. 9 As shown, the X-axis is the inverse of the spraying distance, and the Y-axis is the Ar gas flow rate. The momentum and melting degree of the particles are controlled by adjusting key process parameters such as the Ar gas flow rate and the spraying distance. The higher the momentum and melting degree of the particles, the more the coating tends to have a dense, vertical crack structure. Conversely, the coating tends to have a high porosity, columnar structure or porous structure.

[0056] The present invention is further described below by way of examples.

[0057] Example 1 This embodiment is used to illustrate the thermal barrier coating and the preparation method thereof disclosed in the present invention, and includes the following steps: Using Ni-based high-temperature alloy as substrate; The thermal insulation bottom layer is prepared by atmospheric plasma spraying of yttrium-stabilized zirconia powder. The spraying parameters are: ion spraying current is 450-500A, spraying distance is 110-120mm; spray gun swing rate is 500-600mm / s; Ar gas flow rate is 30-35slpm; H2 flow rate is 6-8slpm; powder feeding amount is 1.9-2.2; and the thickness of the thermal insulation bottom layer is 150-160um.

[0058] A high strain tolerance layer is prepared by radial atomization suspension plasma spraying of yttrium-stabilized zirconia suspension, and the spraying parameters are: plasma spraying current is 600-650A; spraying distance is 90-95mm; Ar gas flow rate is 50-55slpm; H2 flow rate is 10-12slpm; suspension solid content is 18-20%; suspension feeding rate is 20-25ml / min; atomization pressure is 0.04-0.05MPa; and the thickness of the high strain tolerance layer is 150-160um.

[0059] The composite thermal barrier coating prepared in this embodiment has a structure as follows Figure 2 As shown in FIG. 1 , during the preparation of the high strain tolerance layer, when the particles approach the thermal insulation bottom layer, the plasma drag force changes the trajectory of the particles from being perpendicular to the surface of the thermal insulation bottom layer to being along the surface of the thermal insulation bottom layer. These particles collide with the microscopic peaks on the surface, generating a shadow effect. The columns grow at the protrusions to form a columnar structure. Due to the higher spray distance, the momentum of the particles when they reach the thermal insulation bottom layer becomes lower, and the degree of bonding between the plates after the particles are melted is reduced, resulting in a high porosity of 27.73%. Figure 3 All of the pores shown are submicron and nanometer pores, which reduce the thermal conductivity while also reducing the stress expansion factor, so that the high strain tolerance layer has high thermal insulation and thermal shock resistance. The composite thermal barrier coating combines the excellent thermal shock resistance and sintering resistance of the high strain tolerance layer with the advantages of low thermal conductivity of the lamellar yttrium-stabilized zirconia structure. Compared with the single-layer lamellar yttrium-stabilized zirconia structure, it has better performance. After 270 water quenchings, only the high strain tolerance layer peeled off.

[0060] The water quenching thermal shock test conditions are: heating at 1100°C for 5 minutes, then immediately water quenching at room temperature for 10 seconds, and repeating until the coating peeling area exceeds 5%.

[0061] Example 2 This embodiment is used to illustrate the thermal barrier coating and the preparation method thereof disclosed in the present invention, and includes the following steps: Using Ni-based high-temperature alloy as substrate; The thermal insulation bottom layer is prepared by atmospheric plasma spraying of yttrium-stabilized zirconia powder. The spraying parameters are: ion spraying current is 450-500A, spraying distance is 110-120mm; spray gun swing rate is 500-600mm / s; Ar gas flow rate is 30-35slpm; H2 flow rate is 6-8slpm; powder feeding amount is 1.9-2.2; and the thickness of the thermal insulation bottom layer is 150-160um.

[0062] The high strain tolerance layer was prepared by radial atomization suspension plasma spraying of yttrium-stabilized zirconia suspension, and the spraying distance was reduced to 70-75 mm; the Ar gas flow rate was increased to 55-60 slpm; and the other spraying parameters were consistent with those in Example 1.

[0063] The composite thermal barrier coating prepared in this embodiment has a structure as follows Figure 4 As shown, during the preparation of the high strain tolerance layer, the higher deposition temperature can improve the bonding between the sheets, and the sheets have good contact, which makes the entire high strain tolerance layer be regarded as a whole, and also leads to high thermal conductivity and high heat flux. When the molten particles hit the relatively cold insulation bottom layer, the plate formed by the impact cools very quickly, but the cooling shrinkage is limited by the block insulation bottom layer, so the tensile stress is introduced into the high strain tolerance layer. When these stresses exceed the strength of the high strain tolerance layer, vertical cracks will be formed. Due to the reduction of the spraying distance and the increase of the Ar gas flow rate, the momentum obtained by the particles is higher, and the momentum when reaching the insulation bottom layer is also higher, forming a high strain tolerance layer with a dense vertical crack structure. After 260 water quenchings, only the thermal barrier coating peeled off.

[0064] The water quenching thermal shock test conditions are: heating at 1100°C for 5 minutes, then immediately water quenching at room temperature for 10 seconds, and repeating until the coating peeling area exceeds 5%.

[0065] Example 3 This embodiment is used to illustrate the thermal barrier coating and the preparation method thereof disclosed in the present invention, and includes the following steps: The turbine guide blades are clamped on a rotating table, and NiCrAlY is used as the raw material. The bonding layer is prepared by hypersonic flame spraying. The spraying angle is 30-33 degrees relative to the rafters. The spraying parameters are kerosene 25-30L / h, oxygen 800-900L / h, and the spray distance is 300-350mm.

[0066] The turbine guide blades with a bonding layer are fixed on a workbench, and yttrium-stabilized zirconia powder is used for atmospheric plasma spraying to prepare a thermal insulation base layer. The spraying parameters are: ion spraying current is 450-500A, spraying distance is 110-120mm; spray gun swing rate is 500-600mm / s; Ar gas flow rate is 30-35slpm; H2 flow rate is 6-8slpm; powder feeding amount is 1.9-2.2.

[0067] The turbine guide blade formed with the heat-insulating bottom layer is fixed on a workbench, and a high strain tolerance layer is prepared by radial atomization suspension plasma spraying using a yttrium-stabilized zirconia suspension. The spraying parameters are consistent with those in Example 1.

[0068] After testing, the thickness of the thermal insulation bottom layer of the turbine guide blade at the air inlet side is 150-160um, the thickness of the high strain tolerance layer is 100-110um, and Figure 5 The columnar structure is shown, the thickness of the heat insulation bottom layer at the blade back is 190-200um, the high strain tolerance layer is 140-150um, the thickness of the heat insulation bottom layer at the blade basin is 160-170um, the high strain tolerance layer is 90-100um, the thickness of the heat insulation bottom layer at the rafters is 150-160um, and the high strain tolerance layer is 130-140um. This embodiment realizes that the coating structure and thickness of each part of the blade are basically uniform.

[0069] Comparative Example 1 This comparative example is used to compare and illustrate the thermal barrier coating and preparation method thereof disclosed in the present invention, and includes the following steps: Using Ni-based high-temperature alloy as substrate; A high strain tolerance layer was prepared by radial atomization suspension plasma spraying using a yttrium-stabilized zirconia suspension. The spraying parameters were mostly the same as those in Example 1, except that the spray distance was reduced to 65-70 mm; the Ar gas flow rate was increased to 60-65 slpm; and the thickness of the high strain tolerance layer was 300-400 um.

[0070] The dense vertical crack single-layer thermal barrier coating prepared in this comparative example has a structure such as Figure 6As shown, during the preparation of the high strain tolerance layer, the higher deposition temperature can improve the bonding between the sheets, and the sheets have good contact, which makes the entire high strain tolerance layer as a whole, and also leads to high thermal conductivity and high heat flux. When the molten particles hit the relatively cold substrate, the plate formed by the impact cools very quickly, but the cooling shrinkage is limited by the block substrate, so the tensile stress is introduced into the high strain tolerance layer. When these stresses exceed the strength of the high strain tolerance layer, vertical cracks will be formed. Due to the lower spray distance and higher Ar gas flow rate, the particle melting degree is higher, and the momentum reaching the substrate is higher, forming a dense vertical crack thermal barrier coating with a porosity of 11.7%. The improvement of the density of the coating improves the bonding strength of the coating, which can reach 55.61MPa. The introduction of vertical cracks improves the thermal shock resistance and sintering resistance of the high strain tolerance layer. However, compared with the composite structure thermal barrier coating of Example 1, the coating fails to peel off after only 210 water quenchings, and the thermal shock life is shortened by about 20%.

[0071] Comparative Example 2 This comparative example is used to compare and illustrate the thermal barrier coating and preparation method thereof disclosed in the present invention, and includes the following steps: Using Ni-based high-temperature alloy as substrate; A high strain tolerance layer was prepared by radial atomization suspension plasma spraying using a yttrium-stabilized zirconia suspension. The spraying parameters were mostly the same as those in Example 2, except that the Ar gas flow was reduced to 50-55 slpm and the ceramic layer thickness was 300 um.

[0072] The columnar structure single-layer thermal barrier coating prepared in this comparative example has a structure such as Figure 7 As shown, when the particles approach the substrate, the plasma drag force changes the trajectory of the particles from perpendicular to the substrate surface to along the substrate surface. These particles collide with the microscopic peaks on the surface to produce a shadow effect. Columns grow on the asperities to form a columnar structure. Due to the reduction in the Ar gas flow rate, the particles gain a lower momentum, and the particles are more affected by the plasma drag force, thereby forming a columnar structure and improving the strain tolerance of the coating. However, compared with the composite structure thermal barrier coating of Example 2, the coating failed to peel off after only 200 water quenchings, and the thermal shock life was shortened by about 25%.

[0073] Comparative Example 3 This comparative example is used to compare and illustrate the thermal barrier coating and preparation method thereof disclosed in the present invention, and includes the following steps: Using Ni-based high-temperature alloy as substrate; A high strain tolerance layer was prepared by radial atomization suspension plasma spraying using a yttrium-stabilized zirconia suspension. The spraying parameters were mostly the same as those in Example 2, except that the Ar gas flow rate was reduced to 40 slpm; the solid content of the suspension was increased to 30%; the suspension feed rate was increased to 35 ml / min; and the ceramic layer thickness was 150 nm.

[0074] The thermal barrier coating prepared in this comparative example has a structure as Figure 8 As shown in the figure, due to the high solid content, the viscosity of the suspension is increased, making it more difficult to break, and the total feed amount is increased, resulting in insufficient melting, and the lower Ar gas flow rate leads to lower particle momentum, forming a high porosity coating. Compared with the composite structure thermal barrier coating of Example 2, the coating failed to peel off after only 40 water quenchings, and the thermal shock life was shortened by about 85%.

[0075] Comparative Example 4 This comparative example is used to compare and illustrate the thermal barrier coating and preparation method thereof disclosed in the present invention, and includes the following steps: Using Ni-based high-temperature alloy as substrate; The thermal insulation bottom layer is prepared by atmospheric plasma spraying of yttrium-stabilized zirconia powder. The spraying parameters are: ion spraying current is 450-500A, spraying distance is 110-120mm; spray gun swing rate is 500-600mm / s; Ar gas flow rate is 30-35slpm; H2 flow rate is 6-8slpm; powder feeding amount is 1.9-2.2; and the thickness of the thermal insulation bottom layer is 300um.

[0076] The thermal barrier coating prepared in this comparative example has a lamellar structure. Compared with the composite structure thermal barrier coating of Example 1, the coating fails to peel off after only 150 water quenchings, and the thermal shock life is shortened by about 45%.

[0077] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A thermal barrier coating, characterized in that: It includes a thermal insulation bottom layer and a high strain tolerance layer, wherein the thermal insulation bottom layer is located under the high strain tolerance layer, the thermal insulation bottom layer includes a layer of yttrium-stabilized zirconia with stacked layer units, and the high strain tolerance layer includes high strain tolerance yttrium-stabilized zirconia, and the high strain tolerance yttrium-stabilized zirconia has one or more of a vertical crack structure, a columnar structure and a porous structure.

2. The thermal barrier coating according to claim 1, characterized in that: The thickness of the thermal insulation bottom layer is 50-500 μm. In the thermal insulation bottom layer, the transverse major axis of the sheet unit is 5-30 μm, and the longitudinal thickness is 2-10 μm.

3. The thermal barrier coating according to claim 1, characterized in that: The porosity of the thermal insulation bottom layer is 5% to 25%.

4. The thermal barrier coating according to claim 1, characterized in that: The thickness of the high strain tolerance layer is 60-300 μm.

5. The thermal barrier coating according to claim 1, characterized in that: The vertical crack structure includes a plurality of cracks extending along the thickness direction of the high strain tolerance layer, the cracks have a depth of 60-300 μm, a width of 0.3-3 μm, and a density of 2-10 mm -1 ; The columnar structure includes a plurality of columnar microstructures extending along the thickness direction of the high strain tolerance layer, the height of the columnar microstructure is 60-300 μm, and the density is 5-30 mm -1 ; The porous structure includes a plurality of micropores formed inside the high strain tolerance layer, the pore diameter of the micropores is 0.5-5 μm, and the porosity of the porous structure is 25%-45%.

6. The thermal barrier coating according to claim 1, characterized in that: It also includes a bonding layer, the bonding layer is located on a side of the thermal insulation bottom layer away from the high strain tolerance layer, the bonding layer includes at least one of MCrAlY and MCrAlTaY, wherein M is Ni and / or Co; The thickness of the bonding layer is 50-200 μm.

7. A high temperature resistant component, characterized in that: It comprises a hot end component and a thermal barrier coating as claimed in any one of claims 1 to 6, wherein the thermal barrier coating is arranged on the surface of the hot end component, and the hot end component comprises a turbine blade, a combustion chamber, a heat shield, a nozzle, a flame tube or a tail nozzle.

8. The method for preparing a thermal barrier coating according to any one of claims 1 to 6, characterized in that: The steps are as follows: Yttrium-stabilized zirconia powder is used as a raw material for atmospheric plasma spraying to form a layer of yttrium-stabilized zirconia with layer units stacked to obtain a heat-insulating bottom layer; A high strain tolerance layer is formed on the surface of the thermal insulation base layer by using atomized suspension plasma spraying of yttrium stabilized zirconia suspension.

9. The method for preparing a thermal barrier coating according to claim 8, characterized in that: Also includes: MCrAlY and / or MCrAlTaY are used as raw materials for hypersonic flame spraying, wherein M is Ni and / or Co, to prepare a bonding layer on the hot end component, and the spraying parameters are: kerosene 25-30L / h, oxygen 800-900L / h, and spray distance 300-350mm.

10. The method for preparing a thermal barrier coating according to claim 8, characterized in that: The parameters of the atmospheric plasma spraying are: ion spraying current is 450-500A, spraying distance is 110-120mm; spray gun swing speed is 500-600mm / s; Ar gas flow rate is 30-35slpm; H2 flow rate is 6-8slpm, and / or The atomized suspension plasma spraying adopts radial atomized suspension plasma spraying, and the parameters are: plasma spraying current is 600-650A; spraying distance is 60-95mm; Ar gas flow rate is 30-70slpm; H2 flow rate is 10-12slpm; suspension solid content is 18-30%; suspension feeding rate is 20-35ml / min; atomization pressure is 0.04-0.05MPa.

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