Thermal barrier coating for high-temperature alloy surface and preparation method

Abstract

The invention discloses a thermal barrier coating for a high-temperature alloy surface and a preparation method, the thermal barrier coating comprises a bonding layer, a first ceramic thermal insulation layer, a second ceramic thermal insulation layer and a sacrificial coating from near to far from the high-temperature alloy surface, the roughness Ra of the interface of the bonding layer and the first ceramic thermal insulation layer is 11-13 microns, and the roughness Ra of the interface of the second ceramic thermal insulation layer is 11-13 microns. The roughness Ra of the interface of the first ceramic heat insulation layer and the second ceramic heat insulation layer is 12-17 microns, the first ceramic heat insulation layer comprises ZrO2 and Y2O3, the mass percent of Y2O3 is 6%-8%, the second ceramic heat insulation layer comprises ZrO2, Y2O3, Yb2O3 and Gd2O3, the mass percent of Y2O3 is 9%-10%, the mass percent of Yb2O3 is 5%-6%, the mass percent of Gd2O3 is 4.7%-5.7%, the mass percent of Gd2O3 is 5%-6%, and the mass percent of Gd2O3 is 5%-7%. Through spraying equipment, spraying of a bonding layer on the surface of the high-temperature alloy, sand blasting of the bonding layer to improve the surface roughness and spraying of a first ceramic heat insulation layer are completed firstly, in at least the last time of spraying, the spraying angle is changed, the surface roughness of the first ceramic heat insulation layer is improved, and finally, a second ceramic heat insulation layer and a sacrificial coating are sequentially sprayed.

Description

Technical Field

[0001] The invention relates to the field of preparation and repair of thermal barrier coatings, and in particular to a thermal barrier coating for a high-temperature alloy surface and a preparation method thereof. Background Art

[0002] Heavy-duty gas turbines are core power equipment that uses high-temperature fuel gas as a working fluid. They are national strategic high-tech and a symbol of the level of major equipment manufacturing. They are related to national energy security, national defense security and industrial competitiveness. Turbine blades are the key hot end components that determine the output power of gas turbines, and are crucial to the performance of the entire gas turbine. The combustion chamber and turbine components of heavy-duty gas turbines are larger than those of aircraft engines, and the coating area of ​​thermal barrier coatings is much larger than that of similar components of aircraft engines. With the improvement of gas turbine efficiency, the service temperature of turbine blades is also increasing. During the operation of the gas turbine, they are subjected to high-temperature and high-pressure gas impacts exceeding 1400°C. This temperature far exceeds the temperature limit of the high-temperature alloy material used in the matrix (about 1000°C). Therefore, the turbine blades must be cooled, that is, a hollow belt cooling structure is used, and a thermal barrier coating is applied to the gas erosion surface. The combustion chamber must also use a high-temperature alloy as the shell, and a thicker thermal barrier coating is applied inside to ensure that the transition section works safely and reliably at high temperatures.

[0003] As the power level and efficiency of gas turbines increase, the gas inlet temperature increases accordingly. Generally, the gas temperature of F-class gas turbines reaches 1450℃, and that of G / H-class gas turbines increases by 100℃ on this basis. The J-class gas turbine increases by another 100℃ on the basis of the G / H-class gas turbines. Obviously, the improvement in the endurance strength of the new high-temperature alloy cannot reach the 100℃ level. Generally, the long-term operating temperature of the highest-level high-temperature alloy that meets the design conditions is difficult to exceed 1000℃, and the current maximum temperature of the turbine blade alloy of the F-class gas turbine can reach about 900℃. Obviously, the applicability of the thermal barrier coating originally used for the F-class gas turbine of the G / H-class gas turbine is close to the limit. The thermal insulation and temperature resistance provided by the thermal barrier coating required by the J-class gas turbine obviously require a new type of high thermal resistance thermal barrier coating.

[0004] Traditional thermal barrier coatings are composed of a metal bonding layer and a ceramic insulation layer. The metal bonding layer is generally MCrAlY (M is Ni, Co or a mixture of the two). The ceramic insulation layer of the F-class engine uses 6-8%wt yttria-stabilized zirconia. When the insulation demand is high, it is usually achieved by increasing the thickness of the insulation layer and increasing its porosity. YSZ has a phase change at 1170 degrees Celsius, which will cause a 4% change in volume. Under normal circumstances, because this characteristic will increase the risk of shedding, YSZ is generally limited to use between 1200 and 1250°C. New materials with higher temperature resistance and lower thermal conductivity are mainly used in defective pyrochlore materials and their doping types such as Gd 2 Zr 2 O 7,La 2 Zr 2 O 7 , Gd 2 -xRExZr 2 O 7 and La 2 -xRExZr 2 O 7 ; Composite doped t' phase or t phase YSZ, namely GdO-YbO-YO-ZrO, TaO-YO-ZrO, etc. belong to this type, rare earth Ta salts, aluminum magnesium salts, etc.

[0005] Most of the new low thermal conductivity materials cannot be used alone at present, because their physical properties are quite different from those of the bonding layer, and they are easy to fall off when used alone. It is necessary to first spray the oxide-stabilized zirconia as a transition layer after spraying the bonding layer, and then continue to spray the low thermal conductivity material on the oxide-stabilized zirconia. The life of this double-layer coating system is not ideal. In the tests that have been carried out, the ceramic layer and the bonding layer and the oxide-stabilized zirconia are both common peeling locations. In addition, during operation, the gas flow contains SO 2 , K salt, sodium salt and other thermally corrosive substances, containing low-melting-point CMAS dust. For units using abradable coatings, there will also be metal particles and ceramic particles in the airflow, all of which may have an adverse effect on the performance of the coating.

[0006] In patent document CN103874580B, a thermal barrier coating system and method thereof are disclosed, including an inner ceramic layer and an outer ceramic layer. The inner ceramic layer is substantially composed of zirconium oxide stabilized by about 6-about 9% yttria and optionally contains more than 0.5-10% hafnium oxide. The outer ceramic layer is coated on and contacts the inner ceramic layer to define the outermost surface of the coating system. The outer ceramic layer is substantially composed of zirconium oxide stabilized by about 25-about 75% yttria by weight, has a thickness less than that of the inner ceramic layer, and also contains more than 0.5-10% hafnium oxide and optionally 1-10% tantalum oxide. The problem of easy detachment due to the difference in physical properties between the ceramic layer and the bonding layer and reducing the adhesion of contamination is not solved.

[0007] Patent document CN109468639B discloses an ultra-limit zirconium alloy and its preparation method, including a zirconium alloy substrate, on the surface of which a bonding layer, a precious metal layer, a ceramic A layer, a ceramic B layer, a sealing coating, a reflective layer, a reflective refractive layer, and an electrical insulation layer are sequentially deposited. The preparation method of the ultra-limit zirconium alloy is to deposit a bonding layer, a precious metal layer, a ceramic A layer, a ceramic B layer, a sealing coating, a reflective layer, a reflective refractive layer, and an electrical insulation layer on the surface of the zirconium alloy substrate in sequence, but does not solve the problem that the ceramic layer and the bonding layer are easy to fall off due to differences in physical properties, and reduce the problem of contamination adhesion. Summary of the invention

[0008] Based on the above technical problems, the present invention proposes a thermal barrier coating for the surface of a high-temperature alloy and a preparation method thereof, which solves the problem in the prior art that the ceramic layer and the bonding layer are easily detached due to differences in physical properties and reduces contamination adhesion.

[0009] To achieve the above object, the present invention provides a thermal barrier coating for the surface of a high-temperature alloy.

[0010] A thermal barrier coating for a high-temperature alloy surface, comprising a bonding layer, a first ceramic thermal insulation layer, a second ceramic thermal insulation layer and a sacrificial coating from the surface of the high-temperature alloy from near to far, the roughness Ra of the interface between the bonding layer and the first ceramic thermal insulation layer is 11 μm-13 μm, the roughness Ra of the interface between the first ceramic thermal insulation layer and the second ceramic thermal insulation layer is 12 μm-17 μm, and the material composition of the first ceramic thermal insulation layer includes ZrO 2 and Y 2 O 3 , where Y 2 O 3 The mass percentage is 6%-8%, and the material composition of the second ceramic insulation layer includes ZrO 2 , Y 2 O 3 , Yb 2 O 3 and Gd 2 O 3 , where Y 2 O 3 The mass percentage is 9%-10%, Yb 2 O 3 The mass percentage of Gd is 5%-6%, 2 O 3 The mass percentage is 4.7%-5.7%.

[0011] Further, the material composition of the first bonding layer includes Co, Ni, Cr, Al and Y, which contains 31%-33% Ni, 20%-22% Cr, 7%-9% Al and 0.5%-1% Y by mass percentage, and the balance is Co and unavoidable impurities. The particle size of the raw material powder of the first bonding layer is 22μm-45μm, and the thickness of the first bonding layer is 240μm-300μm;

[0012] The material composition of the first bonding layer includes Co, Ni, Cr, Al and Y, which contains 30%-33% Ni, 20%-22% Cr, 6%-9% Al and 0.5%-1% Y in mass percentage, and the remainder is Co and inevitable impurities. The particle size of the raw material powder of the first bonding layer is 45μm-90μm, and the thickness of the second bonding layer is 55μm-65μm.

[0013] Further, the thickness of the first ceramic heat-insulating layer is 225 μm-275 μm;

[0014] The thickness of the second ceramic heat-insulating layer is 230 μm-270 μm.

[0015] Furthermore, the combined thickness of the first ceramic heat-insulating layer and the second ceramic heat-insulating layer is 470 μm-520 μm.

[0016] Furthermore, the porosity deviation between the first ceramic heat-insulating layer and the second ceramic heat-insulating layer is 1%-4%.

[0017] Furthermore, the spraying powder of the sacrificial coating is La 0.5 Yb 0.5 Zr 2 O 7 powder.

[0018] Furthermore, the diameter of the spraying powder is 15 μm-20 μm.

[0019] Furthermore, the sacrificial coating has a thickness of 15 μm-30 μm.

[0020] Furthermore, the surface roughness Ra of the sacrificial coating is 1.19 μm-1.2 μm.

[0021] To achieve the above object, the present invention also provides a method for preparing a thermal barrier coating on a surface of a high-temperature alloy.

[0022] A method for preparing a thermal barrier coating on a surface of a high-temperature alloy, characterized by comprising:

[0023] S1: spraying the raw material powder onto the surface of the high-temperature alloy to a preset thickness through a spraying device to complete the spraying of the bonding layer, and sandblasting the bonding layer to improve the surface roughness;

[0024] S2: spraying the first ceramic thermal insulation layer at the interface of the bonding layer using a spraying device, changing the spraying angle in at least the last spraying to complete the spraying of the first ceramic thermal insulation layer, sandblasting the first ceramic thermal insulation layer to improve the surface roughness, preheating the surface of the first ceramic thermal insulation layer using a plasma flame, and after reaching the preheating temperature, spraying the second ceramic thermal insulation layer according to a predetermined path;

[0025] S3: spraying the sacrificial coating.

[0026] Furthermore, the step S1 further includes:

[0027] First, the first bonding layer is sprayed by supersonic flame spraying to reach a preset thickness, and then the second bonding layer is sprayed by atmospheric plasma spraying.

[0028] Furthermore, the step S1 further includes:

[0029] After the spraying of the bonding layer is completed, aging heat treatment is performed.

[0030] Furthermore, the step S1 includes:

[0031] After the aging heat treatment is completed, masking operations are carried out on the positions that need to be masked, the fixtures are installed and the spraying program is debugged, and the dry ice sandblasting method with particles of 3mm-5mm is used for sandblasting.

[0032] Furthermore, the step S2 further includes:

[0033] In the last 1-2 spraying paths of spraying the first ceramic thermal insulation layer, the spray gun angle is changed from 90 degrees perpendicular to the surface to 60 degrees to 80 degrees for spraying.

[0034] Furthermore, the step S2 further includes:

[0035] After the first ceramic insulation layer is sprayed, different sandblasting tubes are used to use 20-60 mesh fused zirconium crushed sand and dry ice with a particle diameter of 3mm-5mm as sandblasting media to sandblast the surface of the first ceramic insulation layer.

[0036] Furthermore, the step S2 further includes:

[0037] The first ceramic heat-insulating layer is preheated to a temperature of 200°C-500°C.

[0038] Furthermore, the step S3 further includes:

[0039] When spraying the sacrificial coating, the spraying distance is 80 mm-120 mm, and the powder feeding speed is 48 g / min-52 g / min.

[0040] Furthermore, the step S3 further includes:

[0041] After the sacrificial coating is completed, the surface of the sacrificial coating is polished.

[0042] Based on the above technical solution, the present invention has at least the following beneficial effects:

[0043] 1. The present invention proposes a thermal barrier coating for the surface of a high-temperature alloy. Through a series of coating preparation steps, the mechanical bonding force between the interfaces in the thermal barrier coating is significantly improved. The heat resistance of the coating is improved by precise control of the roughness between the bonding layer and the ceramic insulation layer, and surface treatment achieved through special sandblasting technology. By optimizing the spraying parameters and post-processing steps, the present invention greatly reduces the risk of interface contamination that may occur during thermal cycling. In simulation tests, the coating samples using the technology of the present invention showed excellent durability, and its isothermal thermal cycle life was increased from the conventional 400 times to more than 1,000 times.

[0044] 2. The present invention introduces La with self-limiting reaction characteristics 0.5 Yb 0.5 Zr 2 O 7 As a sacrificial coating, it reduces the adhesion of the coating and confines the pollutants in the sacrificial layer so that they do not diffuse inward. At the same time, the structure of the thermal barrier coating in the present invention exhibits higher stability and durability when facing corrosive substances commonly encountered in gas turbine operation. This sacrificial coating can effectively limit the penetration of corrosive substances and protect the underlying thermal barrier coating from damage, thereby extending the service life of the entire coating system.

[0045] 3. The thermal barrier coating structure design proposed in the present invention adopts low thermal conductivity materials and optimized coating pore structure to achieve the coating having both heat insulation and thermal corrosion resistance functions. The coating structure design of the present invention enables the coating to maintain stable performance in the harsh environment of the gas turbine while reducing maintenance costs and frequency.

[0046] 4. The thermal barrier coating proposed in the present invention adopts mainstream coating preparation equipment and optimized spraying parameters to simplify the production process, making the coating preparation process more efficient and economical. By precisely controlling the spraying conditions and post-processing steps, the present invention reduces the defects that may occur in the coating preparation process and improves the consistency and reliability of the coating. The preparation method in the present invention not only improves production efficiency, but also reduces dependence on high-end equipment and complex processes, making the coating technology of the present invention more easily and widely used in industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0048] Figure 1 A cross-sectional view showing a composition structure of a thermal barrier coating according to an embodiment;

[0049] Figure 2A schematic diagram showing dry ice blasting of a bonding layer interface of a thermal barrier coating according to an embodiment;

[0050] Figure 3 A schematic diagram showing simultaneous dry ice blasting and particle blasting at the interface of a bonding layer of a thermal barrier coating according to an embodiment. DETAILED DESCRIPTION

[0051] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0052] The present invention is further described in detail below in conjunction with specific embodiments, and these embodiments cannot be understood as limiting the scope of protection claimed by the present invention. The term "including" when used indicates the existence of a feature, but does not exclude the existence or addition of one or more other features; the orientation or position relationship indicated by the terms "lateral", "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inside", "outside", etc. is based on the orientation or position relationship shown in the drawings, which is only for the convenience of description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention; in addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance.

[0053] In the description, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. In addition, in the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0054] Example

[0055] The present invention provides a thermal barrier coating for a high temperature alloy surface, such as Figure 1 The structure shown in the figure includes a bonding layer, a first ceramic thermal insulation layer, a second ceramic thermal insulation layer and a sacrificial coating, the roughness Ra of the interface between the bonding layer and the first ceramic thermal insulation layer is 11 μm-13 μm, the roughness Ra of the interface between the first ceramic thermal insulation layer and the second ceramic thermal insulation layer is 12 μm-17 μm, and the material composition of the first ceramic thermal insulation layer includes ZrO 2 and Y 2 O 3 , where Y 2 O 3The mass percentage is 6%-8%, and the material composition of the second ceramic insulation layer includes ZrO 2 , Y 2 O 3 , Yb 2 O 3 and Gd 2 O 3 , where Y 2 O 3 The mass percentage is 9%-10%, Yb 2 O 3 The mass percentage of Gd is 5%-6%, 2 O 3 The mass percentage is 4.7%-5.7%.

[0056] Example 1

[0057] A powder with a mass composition of Co, 31% Ni, 20% Cr, 7% Al and 0.5% Y and a particle diameter of 22 μm was used as the raw material powder for the first bonding layer, and a powder with a mass composition of Co, 31% Ni, 20% Cr, 7% Al and 0.5% Y and a particle diameter of 45 μm was used as the raw material powder for the second bonding layer. 2 and Y 2 O 3 , where Y 2 O 3 The mass percentage is 6% and the rest is ZrO 2 The powder is used as the raw material of the first ceramic insulation layer, and the material composition is ZrO 2 , Y 2 O 3 , Yb 2 O 3 and Gd 2 O 3 , where Y 2 O 3 The mass percentage of Yb is 9%, 2 O 3 The mass percentage of Gd is 5%, 2 O 3 The powder with a mass percentage of 4.7% is used as the raw material of the second ceramic insulation layer; the thickness of the first bonding layer is 240μm, the thickness of the second bonding layer is 55μm, the thickness of the first ceramic insulation layer sprayed is 225μm, the thickness of the second ceramic insulation layer sprayed is 230μm, the thickness of the sacrificial coating is 15μm, and the thermal barrier coating prepared in this embodiment has a 1-hour cycle life of more than 800 times after testing.

[0058] In a method for preparing a thermal barrier coating on a surface of a high-temperature alloy in this embodiment, the method includes:

[0059] The first bonding layer is sprayed with 240μm by supersonic flame spraying, and the roughness Ra is 5μm. After reaching the preset thickness, 55μm is sprayed by atmospheric plasma spraying to complete the spraying of the second bonding layer, so that the roughness Ra reaches 11μm. After the bonding layer is sprayed, aging heat treatment is performed, the masking operation is performed on the position to be masked, the fixture is installed, and the spraying program is debugged, such as Figure 2 As shown in the figure, the dry ice sandblasting method with particles of 3mm is used for sandblasting to reduce the original TGO to less than 0.5μm. The first ceramic insulation layer is sprayed. In the last spraying path of the first ceramic insulation layer, the spray gun angle is changed from 90 degrees perpendicular to the surface to 60 degrees for spraying, so that the particle flow obliquely impacts the spraying surface to create more wave-like surfaces; after the first ceramic insulation layer is sprayed, as shown in the figure Figure 3 As shown, different sandblasting tubes are used to use 20-mesh fused zirconium crushed sand and dry ice with a particle diameter of 3 mm as sandblasting media, and the surface of the first ceramic insulation layer is sandblasted together; the surface of the first ceramic insulation layer is preheated using a plasma flame, and the temperature is measured using an infrared temperature measuring device. The preheating temperature reaches 200°C, and the second ceramic insulation layer is sprayed. The first ceramic insulation layer sprayed is 12%, and the second ceramic insulation layer is 14%; finally, when spraying the sacrificial coating, the spraying distance is 100 mm, and the powder feeding speed is 50 g / min. After the sacrificial coating is completed, the roughness Ra is less than 3.2 μm. The surface of the sacrificial coating is sandblasted and polished with sand to make the surface roughness Ra of the sacrificial coating reach 1.2 μm.

[0060] Example 2

[0061] Preferably, a powder with a mass composition of Co, 32% Ni, 21% Cr, 8% Al and 0.7% Y and a particle diameter of 30 μm is used as the raw material powder for the first bonding layer, and a powder with a mass composition of Co, 32% Ni, 21% Cr, 8% Al and 0.7% Y and a particle diameter of 60 μm is used as the raw material powder for the second bonding layer. 2 and Y 2 O 3 , where Y 2 O 3 The powder with a mass percentage of 7% is used as the raw material of the first ceramic insulation layer, and the material composition is ZrO 2 , Y 2 O 3 , Yb 2 O 3 and Gd 2 O 3 , where Y 2 O 3The mass percentage of Yb is 9.5%, 2 O 3 The mass percentage of Gd is 5.5%, 2 O 3 A powder with a mass percentage of 5.2% is used as the raw material of the second ceramic insulation layer; the thickness of the first bonding layer is 270μm, the thickness of the second bonding layer is 60μm, the ratio of the thickness of the first ceramic insulation layer to the thickness of the second ceramic insulation layer is 1:1, the sprayed thickness of the first ceramic insulation layer is 250μm, the sprayed thickness of the second ceramic insulation layer is 250μm, the thickness of the sacrificial coating is 20μm, and the thermal barrier coating prepared in this embodiment has a 1-hour cycle life of more than 1000 times after testing.

[0062] In a method for preparing a thermal barrier coating on a surface of a high-temperature alloy in this embodiment, the method includes:

[0063] Preferably, the first bonding layer is sprayed with 270 μm by supersonic flame spraying, and the roughness Ra is 6 μm. After reaching the preset thickness, 60 μm is sprayed by atmospheric plasma spraying to complete the spraying of the second bonding layer, so that the roughness Ra reaches 13 μm; after the bonding layer is sprayed, aging heat treatment is performed, the position to be shielded is shielded, the fixture is installed and the spraying program is debugged, and the first ceramic insulation layer is sprayed. In the last two spraying paths of the first ceramic insulation layer, the spray gun angle is changed from 90 degrees perpendicular to the surface to 70 degrees for spraying, so that the particle flow obliquely impacts the sprayed surface to create more wave-like surfaces; after the first ceramic insulation layer is sprayed, such as Figure 3 As shown, different sandblasting tubes are used to use 40-mesh fused zirconium crushed sand and dry ice with a particle diameter of 4 mm as sandblasting media, and the surface of the first ceramic insulation layer is sandblasted together; the surface of the first ceramic insulation layer is preheated using a plasma flame, and the temperature is measured using an infrared temperature measuring device. The preheating temperature reaches 300°C, and the second ceramic insulation layer is sprayed. The first ceramic insulation layer obtained by spraying is 13%, and the second ceramic insulation layer is 14%; finally, the sacrificial coating is sprayed, and the other method steps are the same as those in Example 1, which will not be repeated here.

[0064] Example 3

[0065] A powder with a mass composition of Co, 33% Ni, 22% Cr, 9% Al and 1% Y and a particle diameter of 45 μm was used as the raw material powder for the first bonding layer, and a powder with a mass composition of Co, 33% Ni, 22% Cr, 9% Al and 1% Y and a particle diameter of 90 μm was used as the raw material powder for the second bonding layer. 2 and Y 2 O 3 , where Y2 O 3 The powder with a mass percentage of 8% is used as the raw material of the first ceramic insulation layer, and the material composition is ZrO 2 , Y 2 O 3 , Yb 2 O 3 and Gd 2 O 3 , where Y 2 O 3 The mass percentage of Yb is 10%, 2 O 3 The mass percentage of Gd is 6%, 2 O 3 The powder with a mass percentage of 5.7% is used as the raw material of the second ceramic insulation layer; the thickness of the first bonding layer is 300μm, the thickness of the second bonding layer is 65μm, the thickness of the first ceramic insulation layer sprayed is 275μm, the thickness of the second ceramic insulation layer sprayed is 270μm, and the thickness of the sacrificial coating is 30μm. After testing, the thermal barrier coating prepared in this embodiment has a 1-hour cycle life of more than 900 times.

[0066] In a method for preparing a thermal barrier coating on a surface of a high-temperature alloy in this embodiment, the method includes:

[0067] The first bonding layer is sprayed with 300μm by supersonic flame spraying, and the roughness Ra is 5μm. After reaching the preset thickness, 65μm is sprayed by atmospheric plasma spraying to complete the spraying of the second bonding layer, so that the roughness Ra reaches 12μm. After the bonding layer is sprayed, aging heat treatment is carried out, the positions to be shielded are shielded, the fixture is installed and the spraying program is debugged, and the first ceramic insulation layer is sprayed. In the last two spraying paths of the first ceramic insulation layer, the spray gun angle is changed from 90 degrees perpendicular to the surface to 80 degrees for spraying, so that the particle flow obliquely impacts the spraying surface to create more wave-like surfaces. After the first ceramic insulation layer is sprayed, Figure 3 As shown, different sandblasting tubes are used to use 60-mesh fused zirconium crushed sand and dry ice with a particle diameter of 5 mm as sandblasting media, and the surface of the first ceramic insulation layer is sandblasted together; the surface of the first ceramic insulation layer is preheated using a plasma flame, and the temperature is measured using an infrared temperature measuring device. The preheating temperature reaches 500°C, and the second ceramic insulation layer is sprayed. The first ceramic insulation layer obtained by spraying is 12%, and the second ceramic insulation layer is 15%; finally, the sacrificial coating is sprayed, and the other method steps are the same as those in Example 1, which will not be repeated here.

[0068] In summary, it can be seen from the above description that the above embodiments of the present invention achieve the following technical effects:

[0069] 1. The present invention proposes a thermal barrier coating for the surface of a high-temperature alloy. Through a series of coating preparation steps, the mechanical bonding force between the interfaces in the thermal barrier coating is significantly improved. The heat resistance of the coating is improved by precise control of the roughness between the bonding layer and the ceramic insulation layer, and surface treatment achieved through special sandblasting technology. By optimizing the spraying parameters and post-processing steps, the present invention greatly reduces the risk of interface contamination that may occur during thermal cycling. In simulation tests, the coating samples using the technology of the present invention showed excellent durability, and its isothermal thermal cycle life was increased from the conventional 400 times to more than 1,000 times.

[0070] 2. The present invention introduces La with self-limiting reaction characteristics 0.5 Yb 0.5 Zr 2 O 7 The powder acts as a sacrificial coating, reduces the adhesion of the coating, and at the same time confines the pollutants in the sacrificial layer and prevents them from diffusing inward. At the same time, the structure of the thermal barrier coating in the present invention exhibits higher stability and durability when facing corrosive substances commonly seen in gas turbine operation. This sacrificial coating can effectively limit the penetration of corrosive substances and protect the underlying thermal barrier coating from damage, thereby extending the service life of the entire coating system.

[0071] 3. The thermal barrier coating structure design proposed in the present invention adopts low thermal conductivity materials and optimized coating pore structure to achieve the coating having both heat insulation and thermal corrosion resistance functions. The coating structure design of the present invention enables the coating to maintain stable performance in the harsh environment of the gas turbine while reducing maintenance costs and frequency.

[0072] 4. The thermal barrier coating proposed in the present invention adopts mainstream coating preparation equipment and optimized spraying parameters to simplify the production process, making the coating preparation process more efficient and economical. By precisely controlling the spraying conditions and post-processing steps, the present invention reduces the defects that may occur in the coating preparation process and improves the consistency and reliability of the coating. The preparation method in the present invention not only improves production efficiency, but also reduces dependence on high-end equipment and complex processes, making the coating technology of the present invention more easily and widely used in industrial production.

[0073] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

[0074] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0075] It should be noted that, in the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

Claims

1. A thermal barrier coating for a high temperature alloy surface, characterized in that: Starting from the surface of the high-temperature alloy, from near to far, it includes a bonding layer, a first ceramic thermal insulation layer, a second ceramic thermal insulation layer and a sacrificial coating. The roughness Ra of the interface between the bonding layer and the first ceramic thermal insulation layer is 11μm-13μm, the roughness Ra of the interface between the first ceramic thermal insulation layer and the second ceramic thermal insulation layer is 12μm-17μm, the porosity of the first ceramic thermal insulation layer and the second ceramic thermal insulation layer is 12%-15%, the material composition of the first ceramic thermal insulation layer includes ZrO2 and Y2O3, wherein the mass percentage of Y2O3 is 6%-8%, the material composition of the second ceramic thermal insulation layer includes ZrO2, Y2O3, Yb2O3 and Gd2O3, wherein the mass percentage of Y2O3 is 9%-10%, the mass percentage of Yb2O3 is 5%-6%, and the mass percentage of Gd2O3 is 4.7%-5.7%.

2. The thermal barrier coating according to claim 1, characterized in that: The bonding layer includes a first bonding layer and a second bonding layer, The material composition of the first bonding layer includes Co, Ni, Cr, Al and Y, which contains 31%-33% Ni, 20%-22% Cr, 7%-9% Al and 0.5%-1% Y by mass percentage, and the balance is Co and unavoidable impurities. The particle size of the raw material powder of the first bonding layer is 22μm-45μm, and the thickness of the first bonding layer is 240μm-300μm; The material composition of the second bonding layer includes Co, Ni, Cr, Al and Y, which contains 30%-33% Ni, 20%-22% Cr, 6%-9% Al and 0.5%-1% Y in mass percentage, and the remainder is Co and unavoidable impurities. The particle size of the raw powder of the first bonding layer is 45μm-90μm, and the thickness of the second bonding layer is 55μm-65μm.

3. The thermal barrier coating according to claim 1, characterized in that: include, The thickness of the first ceramic heat-insulating layer is 225 μm-275 μm; The thickness of the second ceramic heat-insulating layer is 230 μm-270 μm.

4. The thermal barrier coating according to claim 1, characterized in that: include, The combined thickness of the first ceramic heat-insulating layer and the second ceramic heat-insulating layer is 470 μm-520 μm.

5. The thermal barrier coating according to claim 1, characterized in that: include, The porosity deviation between the first ceramic heat-insulating layer and the second ceramic heat-insulating layer is 1%-4%.

6. The thermal barrier coating according to claim 1, characterized in that: include, The spraying powder of the sacrificial coating is La 0.5 Yb 0.5 Zr2O7 powder.

7. The thermal barrier coating according to claim 6, characterized in that: include, The diameter of the spraying powder is 15 μm-20 μm.

8. The thermal barrier coating according to claim 1, characterized in that: include, The thickness of the sacrificial coating is 15 μm-30 μm.

9. The thermal barrier coating according to claim 1, characterized in that: include, The surface roughness Ra of the sacrificial coating is 1.19 μm-1.2 μm.

10. A method for preparing a thermal barrier coating for a high-temperature alloy surface as claimed in claim 1, wherein the thermal barrier coating comprises, from near to far from the surface of the high-temperature alloy, a bonding layer, a first ceramic insulation layer, a second ceramic insulation layer and a sacrificial coating, characterized in that: include: S1: spraying the raw material powder onto the surface of the high-temperature alloy to a preset thickness through a spraying device to complete the spraying of the bonding layer, and sandblasting the bonding layer to improve the surface roughness; S2: spraying the first ceramic thermal insulation layer at the interface of the bonding layer using a spraying device, changing the spraying angle in at least the last spraying to complete the spraying of the first ceramic thermal insulation layer, sandblasting the first ceramic thermal insulation layer to improve the surface roughness, preheating the surface of the first ceramic thermal insulation layer using a plasma flame, and after reaching the preheating temperature, spraying the second ceramic thermal insulation layer according to a predetermined path; S3: spraying the sacrificial coating.

11. The method according to claim 10, characterized in that: The step S1 further includes: First, the first bonding layer is sprayed by supersonic flame spraying to reach a preset thickness, and then the second bonding layer is sprayed by atmospheric plasma spraying.

12. The method according to claim 10, characterized in that: The step S1 further includes: After the spraying of the bonding layer is completed, aging heat treatment is performed.

13. The method according to claim 12, characterized in that: The step S1 includes: After the aging heat treatment is completed, masking operations are carried out on the positions that need to be masked, the fixtures are installed and the spraying program is debugged, and the dry ice sandblasting method with particles of 3mm-5mm is used for sandblasting.

14. The method according to claim 10, characterized in that: The step S2 further includes: In the last 1-2 spraying paths of spraying the first ceramic thermal insulation layer, the spray gun angle is changed from 90 degrees perpendicular to the surface to 60 degrees to 80 degrees for spraying.

15. The method according to claim 10, characterized in that: The step S2 further includes: After the first ceramic insulation layer is sprayed, different sandblasting tubes are used to use 20-60 mesh fused zirconium crushed sand and dry ice with a particle diameter of 3mm-5mm as sandblasting media to sandblast the surface of the first ceramic insulation layer.

16. The method according to claim 10, characterized in that: The step S2 further includes: The first ceramic heat-insulating layer is preheated to a temperature of 200°C-500°C.

17. The method according to claim 10, characterized in that: The step S3 further includes: When spraying the sacrificial coating, the spraying distance is 80 mm-120 mm, and the powder feeding speed is 48 g / min-52 g / min.

18. The method according to claim 10, characterized in that: The step S3 further includes: After the sacrificial coating is completed, the surface of the sacrificial coating is polished.

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