Preparation method of thermal barrier coating alpha-Al2O3 thermal growth oxide

Abstract

The invention provides a preparation method of a thermal barrier coating alpha-Al2O3 thermal growth oxide, and belongs to the technical field of surface engineering. The preparation method comprises the following steps: preparing the MCrAlY bonding layer on the surface of a sample; the surface of the MCrAlY bonding layer is cleaned; raising the temperature to a first preset temperature at a heating rate of 50-80 DEG C / s, performing first heating treatment on the cleaned MCrAlY bonding layer, and generating an alpha-Al2O3-based TGO film with a first thickness on the surface of the MCrAlY bonding layer; and cooling to a second preset temperature, and carrying out secondary heating treatment on the MCrAlY bonding layer, so that the alpha-Al2O3-based TGO film on the surface of the MCrAlY bonding layer continuously grows to a second thickness. According to the method, the rapid heating and segmented heat treatment technology is adopted, the thermal barrier coating with the alpha-Al2O3 thermal growth oxide can be produced and prepared in the atmospheric environment, the process is simple, the implementation difficulty is low, and the production cost is low; and meanwhile, the thermal growth stress is reduced, the coating is effectively prevented from premature failure, and the technical requirement for pre-oxidation of the thermal barrier coating of the gas turbine blade is met.

Description

Technical Field

[0001] The invention belongs to the technical field of surface engineering, and in particular relates to a method for preparing alpha-Al2O3 thermal growth oxide of a thermal barrier coating. Background Art

[0002] Gas turbines are important equipment for electric power and aviation propulsion, and their core hot end components serve in an environment with a temperature above 1300°C. Metal blade materials alone cannot serve for a long time at this temperature, and thermal barrier coatings are required for protection. The thermal barrier coating system is a multi-layer structure system, which is mainly composed of a high-temperature alloy substrate (high-temperature blades), a bonding layer, a ceramic thermal insulation coating, and thermally grown oxide (TGO) generated at the interface between the bonding layer and the ceramic coating. Thermally grown oxide is generated during heat treatment or high-temperature service. Elements such as Al, Cr, and Ni in the bonding layer diffuse to the surface of the bonding layer in a high-temperature environment; at the same time, because the YSZ coating is an oxygen ion conductor at high temperatures, oxygen diffuses to the interface through vacancies or gaps in the coating and combines with Al, Cr, Ni, etc. to form oxides.

[0003] Usually in industrial production, after the coating of the gas turbine blade is prepared, it needs to be heat treated. On the one hand, it promotes the diffusion of elements in the thermal spray bonding layer to ensure the element supply and coating density during the growth of TGO; on the other hand, a layer of TGO with a low growth rate, uniformity and continuity is generated in advance, thereby protecting the bonding layer and reducing the oxidation rate of the bonding layer. The composition of thermally grown oxide (TGO) is usually Al2O3, NiO, Cr2O3 and AB2O4 (A = Ni, Co; B = Al, Cr) type spinel. Among them, α-Al2O3 is a kind of TGO with the advantages of high bonding strength with the bonding layer and ceramic coating and strong oxidation resistance. α-Al2O3 with uniform and continuous thickness is an ideal thermally grown oxide. However, under industrial production or laboratory conditions, TGO is usually not a single α-Al2O3 oxide, but the above-mentioned multiple oxides coexist. In laboratories or industries, a high vacuum or inert gas environment is usually used to reduce the oxygen partial pressure in the heat treatment space where the coating is located, thereby inhibiting or reducing the production of non-Al2O3-based TGO. Usually, it is difficult for an inert gas environment to meet the vacuum requirements, resulting in the obtained metal oxide particles still including components such as nickel oxide, chromium oxide, and cobalt oxide. In addition, when a high vacuum vacuum furnace is used to prepare thermal barrier coatings, the required production conditions are high, the preparation time is long, and the production cost is high, which is not conducive to industrial application. Summary of the invention

[0004] The present invention aims to at least solve the technical problems existing in the prior art such as high production conditions, high cost, long time consumption, and complex composition of pre-produced TGO, and provide a method for preparing a thermal barrier coating having an α-Al2O3-based TGO film in an atmospheric environment.

[0005] The present invention provides a method for preparing a thermal barrier coating α-Al2O3 thermal growth oxide, the preparation method comprising:

[0006] Prepare an MCrAlY bonding layer on the surface of the sample;

[0007] Cleaning the surface of the MCrAlY bonding layer;

[0008] Heating the cleaned MCrAlY bonding layer to a first preset temperature at a heating rate of 50 to 80° C. / s to form an α-Al2O3-based TGO film of a first thickness on the surface of the MCrAlY bonding layer;

[0009] The temperature is lowered to a second preset temperature, and the MCrAlY bonding layer is subjected to a second heat treatment, so that the α-Al2O3-based TGO film on the surface of the MCrAlY bonding layer continues to grow to a second thickness.

[0010] Optionally, the first preset temperature is 1100°C to 1200°C.

[0011] Optionally, the first heating treatment lasts for 5 to 10 minutes.

[0012] Optionally, the first thickness is 0.4-0.8 μm.

[0013] Optionally, the second preset temperature is 850°C to 1050°C.

[0014] Optionally, the second heating treatment lasts for 20 min to 35 min.

[0015] Optionally, the second thickness is 1.0 μm to 2 μm.

[0016] Optionally, the cleaned MCrAlY bonding layer is subjected to a first heating treatment and a second heating treatment by a flame heating method or an induction heating method.

[0017] The present invention provides a method for preparing a thermal barrier coating α-Al2O3 thermal growth oxide, the preparation method comprising: preparing an MCrAlY bonding layer on the surface of a sample; cleaning the surface of the MCrAlY bonding layer; heating to a first preset temperature at a heating rate of 50 to 80°C / s, performing a first heat treatment on the cleaned MCrAlY bonding layer, and generating an α-Al2O3-based TGO film of a first thickness on the surface of the MCrAlY bonding layer; cooling to a second preset temperature, performing a second heat treatment on the MCrAlY bonding layer, and growing the α-Al2O3-based TGO film on the surface of the MCrAlY bonding layer to a second thickness. The method of the present invention adopts rapid heating and segmented heat treatment technology, and can realize the preparation of an α-Al2O3-based TGO film thermal barrier coating in an atmospheric environment, and the process is simple, the implementation difficulty is low, and the production cost is low; at the same time, the thermal growth stress is reduced, and the premature failure of the coating is effectively prevented, and the technical requirements for pre-oxidation of thermal barrier coatings for gas turbine blades are met. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A flowchart of a method for preparing an α-Al2O3-based TGO film in a thermal barrier coating according to an embodiment of the present invention;

[0019] Figure 2 is a diagram showing the organizational structure of the α-Al2O3-based TGO film after the first heating in Example 1 of the present invention;

[0020] Figure 3 This is a diagram of the organizational structure of the α-Al2O3-based TGO film after two heatings in Example 1 of the present invention. DETAILED DESCRIPTION

[0021] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. It should be understood that the specific embodiments described herein are only used to explain the present invention and are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work are within the scope of protection of the present invention.

[0022] like Figure 1 As shown, the present invention provides a method S100 for preparing a thermal barrier coating α-Al2O3 thermal growth oxide, which specifically includes the following steps S110 to S140:

[0023] S110. Prepare an MCrAlY bonding layer on the surface of the sample.

[0024] It should be noted that the samples targeted by this embodiment are mainly samples of materials such as gas turbine blades or other nickel-based high-temperature alloy sheets, and no specific limitation is made to this.

[0025] It should be further explained that the present embodiment does not specifically limit the method for preparing the MCrAlY bonding layer on the surface of the sample, for example, thermal spraying or cold spraying and other technologies.

[0026] It should be noted that the present embodiment does not specifically limit the material and thickness of the MCrAlY bonding layer prepared on the sample surface. For example, M in the MCrAlY bonding layer may be a Co element, a Ni element, or a Co and Ni element. Preferably, the MCrAlY bonding layer is a NiCoCrAlTaY bonding layer. In addition, the thickness of the MCrAlY bonding layer may be 0.1-0.5 mm. For example, 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, etc.

[0027] S120. Clean the surface of the MCrAlY bonding layer.

[0028] Specifically, a high-pressure airflow is used to purge the surface of the bonding layer to clean up poorly bonded particles or floating dust, so as to avoid the failure to form an α-Al2O3-based TGO film due to weak particle bonding and failure to replenish Al in the particles during the heating process.

[0029] In some preferred embodiments, the pressure of the high-pressure air flow is 0.5-1.0 MPa, for example, 0.5 MPa, 0.7 MPa, 0.8 MPa, 1.0 MPa, etc.

[0030] S130, heating the cleaned MCrAlY bonding layer to a first preset temperature at a heating rate of 50°C / s to 80°C / s, and performing a first heat treatment on the MCrAlY bonding layer to form an α-Al2O3-based TGO film of a first thickness on the surface of the MCrAlY bonding layer.

[0031] Specifically, a flame heating or induction heating method is used to perform a first rapid heating treatment on the surface of the workpiece or sample of the cleaned MCrAlY bonding layer, with the temperature being raised to 1100°C to 1200°C at a heating rate of 50°C / s to 80°C / s, and the heating treatment is performed for 5min to 10min to generate a first α-Al2O3-based TGO film with a thickness of 0.4μm to 0.8μm on the surface of the MCrAlY bonding layer.

[0032] In some preferred embodiments, the first thickness may be preferably 0.4 μm, 0.6 μm, or 0.8 μm.

[0033] As a further preferred scheme, the first preset temperature may be preferably 1100°C, 1150°C, 1200°C, the heating rate of the first heating treatment may be preferably 50°C / s, 60°C / s, 70°C / s, 80°C / s, etc., and the time of the first heating treatment may be preferably 5min, 6min, 7min, 8min, 9min, 10min.

[0034] It should be noted that when the MCrAlY bonding layer is heated by the flame heating method, the flame is used to heat the back of the alloy, and the temperature is detected by an infrared thermometer on the front. The gas flow and power of the flame gun are adjusted to make the heating rate and the first preset temperature reach the preset values. After the heat preservation treatment, an α-Al2O3-based TGO film with a first thickness is formed on the MCrAlY bonding layer.

[0035] It should be further explained that when the MCrAlY bonding layer is heated by the induction heating method, a high-frequency induction heating coil can be wrapped around the sample and heated as a whole. After reaching a preset heating rate and a first preset temperature, the sample is subjected to a heat preservation treatment to form an α-Al2O3-based TGO film having a first thickness on the MCrAlY bonding layer.

[0036] In this embodiment, a uniform and continuous α-Al2O3-based TGO film can be quickly formed on the surface of the bonding layer by adopting a rapid heating method, and the heat treatment time is short, only 5-10 minutes.

[0037] S140, cooling to a second preset temperature, and performing a second heat treatment on the MCrAlY bonding layer, so that the α-Al2O3-based TGO film on the surface of the MCrAlY bonding layer continues to grow to a second thickness.

[0038] Specifically, after the first heat treatment of the MCrAlY bonding layer, it is necessary to cool it down and heat the MCrAlY bonding layer again at a relatively low temperature so that the α-Al2O3-based TGO film continues to grow and the thickness increases. After two heat treatments, an α-Al2O3-based TGO film with a thickness of 1.0 to 2 μm is finally obtained. In other words, after the first heat treatment, an α-Al2O3-based TGO film of a certain thickness is first generated on the surface of the MCrAlY bonding layer, and then it is cooled to a certain temperature and then heat-insulated to promote the growth of oxides and the diffusion of the bonding layer, and further form an α-Al2O3-based TGO film to increase the final thickness of the α-Al2O3-based TGO film. That is, the second thickness includes both the thickness of the α-Al2O3-based TGO film formed by the second heat treatment and the first thickness formed by the first heat treatment.

[0039] In some preferred embodiments, the second thickness obtained after two heating treatments is 1.0-2.0 μm, for example, 1.0 μm, 1.2 μm, 1.5 μm, 1.8 μm, 2.0 μm, etc.

[0040] In some other preferred embodiments, the second preset temperature is 850° C. to 1050° C., and the second heating treatment time is 20 min to 35 min.

[0041] As a further preferred scheme, the second preset temperature may be preferably 850°C, 950°C, 1000°C, 1050°C, the cooling rate may be preferably 10°C / s, 15°C / s, 20°C / s, etc., and the time for the second heating treatment may be preferably 20min, 25min, 30min, 35min.

[0042] It should be further explained that after the MCrAlY bonding layer is heated for the first time by the flame heating method, the flame distance is adjusted and the temperature is lowered to a second preset temperature at a preset cooling rate. After the heat preservation treatment, the thickness of the MCrAlY bonding layer is further increased.

[0043] It should be noted that after the MCrAlY bonding layer is heated for the first time by induction heating, the heating power is adjusted and the temperature is lowered to a second preset temperature at a preset cooling rate. After heat preservation treatment, the thickness of the MCrAlY bonding layer is further increased.

[0044] In this embodiment, by adopting a rapid and high-speed heating method, based on the different Gibbs free energy and required oxygen partial pressure of metal elements such as Al, Cr, and Ni during the oxidation process, as shown in Table 1, the Gibbs free energy of Al2O3 generation is much lower than the Gibbs free energy and oxygen partial pressure required for the formation of oxides such as NiO, Cr2O3 and AB2O4. In other words, the formation conditions of aluminum oxide are the lowest. Among the above oxides, Al2O3 will be produced before other oxides. Based on this, the present embodiment innovatively uses a short-term rapid heating method to cause rapid preferential oxidation of the Al element. When the oxides of Cr, Co, Ni, etc. have not yet reached the generation conditions, a dense and continuous α-Al2O3-based TGO film has been established on the coating surface. At this time, the high-temperature heating is exited, the heating temperature is lowered, and the oxidation activity of other elements is further reduced. At the same time, since a dense and continuous α-Al2O3-based TGO film has been produced on the coating surface, the oxygen partial pressure between the bonding layer metal and the TGO film is reduced, which can achieve the same effect as high vacuum heat treatment, effectively inhibiting the generation of other non-α-Al2O3-based TGO films, and thus achieving the formation of only α-Al2O3-based TGO film on the bonding layer.

[0045] Table 1 Gibbs free energy of formation of different oxides and required minimum oxygen partial pressure

[0046]

[0047]

[0048] In this embodiment, the thermal barrier coating formed by the above method includes an MCrAlY bonding layer and an α-Al2O3-based TGO film stacked on the surface of the sample, wherein the MCrAlY bonding layer may preferably be a NiCoCrAlTaY bonding layer, the thickness of the MCrAlY bonding layer may preferably be 0.1-0.5 mm, and the thickness of the α-Al2O3-based TGO film is 1.0-2 μm. The thermally grown oxide has the advantages of high bonding strength with the bonding layer and strong oxidation resistance.

[0049] Of course, it should be understood that the thermal barrier coating may also include a thermal insulation coating, that is, a thermal insulation coating is formed on the surface of the α-Al 2 O 3 -based TGO film, for example, a YSZ ceramic coating.

[0050] It should be noted that since the α-Al2O3-based TGO membrane of the present embodiment is realized based on rapid heat treatment, the order of formation of the above-mentioned thermal insulation coating is not specifically limited. For example, an α-Al2O3-based TGO membrane may be first formed on the surface of the bonding layer by heat treatment, and then the thermal insulation coating is prepared on the α-Al2O3-based TGO membrane. Alternatively, a thermal insulation coating may be first prepared on the bonding layer, and then an α-Al2O3-based TGO membrane may be formed between the bonding layer and the thermal insulation coating by heat treatment.

[0051] In this embodiment, by adopting a rapid heat treatment method, an α-Al2O3-based TGO film can be produced on the surface of the bonding layer in an atmospheric environment without the need for extremely high vacuum or high-purity inert atmosphere furnaces and other equipment. The production conditions are low and the preparation time is short, which is conducive to industrial application.

[0052] The preparation method of thermal barrier coating α-Al2O3 thermal growth oxide will be further described below in conjunction with specific examples:

[0053] Example 1

[0054] The preparation method of the thermal barrier coating α-Al2O3 thermal growth oxide in this example includes the following steps:

[0055] S1. A NiCoCrAlTaY bonding layer with a thickness of about 0.2 mm is prepared on the surface of a nickel-based high-temperature alloy disc with a diameter of 25 mm by using a supersonic flame spraying process (other thermal spraying processes may also be used).

[0056] S2. After cooling, the sample surface is cleaned with 0.7MPa compressed air to remove metal particles or floating dust with weak adhesion, so as to avoid the failure to form α-Al2O3-based TGO film due to weak particle bonding and lack of Al in the particles during heating.

[0057] S3, using flame heating method to heat the back of nickel-based alloy, using infrared thermometer to detect temperature on the front, adjusting the gas flow and power of the flame gun to make the heating rate of the coating surface temperature reach 80℃ / s, after about 12s, the temperature reaches 1150℃, and the high temperature is maintained for 6min, then the first α-Al2O3-based TGO film with a thickness of about 0.51μm can be generated on the coating surface, such as Figure 2 As shown, the black line is α-Al2O3-based TGO film.

[0058] S4, adjust the flame distance, reduce the coating surface temperature to 850℃ within 10s, maintain for 35min, promote the internal diffusion of the coating, promote the growth of α-Al2O3-based TGO film, and make the α-Al2O3-based TGO film continue to grow to 2μm, that is, finally obtain a 2μm thick α-Al2O3-based TGO film on the NiCoCrAlTaY bonding layer, such as Figure 3 shown.

[0059] S5. The thermal barrier coating can be prepared by spraying YSZ ceramic coating on the surface of the oxidized coating using plasma spraying.

[0060] In this embodiment 1, rapid heat treatment is performed before spraying the ceramic coating, and no post-heat treatment is required after the coating is sprayed.

[0061] Example 2

[0062] The preparation process is basically the same as that of Example 1, except that: after step S2, step S5 is performed first and then steps S3 and S4 are performed, that is, the ceramic coating is sprayed immediately after the NiCoCrAlTaY bonding layer is prepared, and then flame rapid heat treatment is performed, and a 2μm thick α-Al2O3-based TGO film can also be finally obtained on the NiCoCrAlTaY bonding layer.

[0063] Example 3

[0064] The preparation process is basically the same as that of Example 1, except that: Example 3 is aimed at real gas turbine blades, and high-frequency induction heating is used in steps S3 and S4, that is, a NiCoCrAlTaY bonding layer with a thickness of about 0.2 mm is prepared on the surface of the gas turbine blade, and the bonding layer is heated by high-frequency induction heating to finally obtain an α-Al2O3-based TGO film with a thickness of 2 μm, and then a YSZ ceramic coating is sprayed on the oxidized surface by plasma spraying.

[0065] Example 4

[0066] The preparation process is basically the same as that of Example 3, except that: after step S2, step S5 is performed first and then S3 and S4, that is, a NiCoCrAlTaY bonding layer with a thickness of about 0.2 mm is prepared on the surface of the gas turbine blade, and a plasma sprayed ceramic coating is used on the surface of the NiCoCrAlTaY bonding layer. After that, the bonding layer is heated by high-frequency induction heating, and finally a 2 μm thick α-Al2O3-based TGO film is obtained.

[0067] Example 5

[0068] The preparation process is basically the same as that of Example 1, with the difference that in step S3, the first heating rate is 50°C / s. After about 20s, the temperature reaches 1200°C, and a 2μm α-Al2O3-based TGO film can still be obtained. Within the heating rate range of Example 5, changing the heating rate has no obvious effect on the final thickness of TGO.

[0069] Example 6

[0070] The preparation process is basically the same as that of Example 1, except that: in step S3, the first heating rate is 30°C / s, and an α-Al2O3-based TGO film with a first thickness of about 0.53 μm can be obtained. At the same time, TGO also contains oxides such as Cr2O3 and NiAl2O4, which cannot achieve the purpose of the present invention.

[0071] Example 7

[0072] The preparation process is basically the same as that of Example 1, except that in step S3, the first heating rate is 90°C / s. This heating rate may cause the TGO film to break and peel off, and the continuity and thickness uniformity of the TGO film are poor, and the purpose of the present invention cannot be achieved.

[0073] Example 8

[0074] The preparation process is basically the same as that of Example 1, except that: in step S3, the first preset temperature of the first heat treatment reaches 900°C, which is lower than the first preset temperature minimum value of 1100°C required by the present invention, and the obtained TGO film structure is uneven, with the presence of Cr2O3, NiAl2O4 and needle-shaped θ-Al2O3.

[0075] Example 9

[0076] The preparation process is basically the same as that of Example 1, except that in step S3, the first preset temperature of the first heat treatment reaches 1200°C, and an α-Al2O3-based TGO film with a first thickness of about 0.8 μm can be obtained.

[0077] Example 10

[0078] The preparation process is basically the same as that of Example 1, except that: in step S3, the first preset temperature of the first heat treatment reaches 1300°C, the material burns and deforms, the growth kinetic energy of Cr2O3 and NiAl2O4 increases dramatically, and the TGO component is impure.

[0079] Embodiment 11

[0080] The preparation process is basically the same as that of Example 1, except that: in step S3, the duration of the first heating treatment is less than 5 minutes, which will cause TGO discontinuity and low thickness. In the subsequent second stage heating process, O will pass through the thinner TGO film and react with non-Al elements to produce non-α-Al2O3 oxides.

[0081] Example 12

[0082] The preparation process is basically the same as that in Example 1, except that: in step S3, the duration of the first heat treatment is greater than 10 minutes. Maintaining a relatively high growth rate at this time will cause the bonding layer surface to be depleted in Al, and elements such as Cr and Ni will be oxidized, and oxides such as Cr2O3 and NiAl2O4 will be produced in the TGO film.

[0083] Example 13

[0084] The preparation process is basically the same as that of Example 1, except that in step S4, the second preset temperature of the second heat treatment is 1050°C, which can produce an α-Al2O3-based TGO film with a second thickness of about 2 μm.

[0085] Embodiment 14

[0086] The preparation process is basically the same as that of Example 1, except that: in step S4, the second preset temperature of the second heat treatment is 1100°C, which is greater than 1050°C. At this time, the higher TGO growth rate will cause the surface of the bonding layer to be Al-poor, and the activity of elements such as Cr and Ni will increase, oxidation will occur, and oxides such as Cr2O3 and NiAl2O4 will be produced in the TGO film.

[0087] Embodiment 15

[0088] The preparation process is basically the same as that of Example 1, except that: in step S4, the second preset temperature of the second heat treatment is less than 850°C, at which time no densification effect can be formed, and at the same time, the diffusion capacity of Al is reduced, and the growth of the α-Al2O3-based TGO film cannot be promoted.

[0089] Example 16

[0090] The preparation process is basically the same as that of Example 1, except that: in step S4, the duration of the second heating treatment is less than 20 minutes, which will cause the final thickness of the TGO film to be relatively low, and non-α-Al2O3 oxides will be produced prematurely during the service life.

[0091] Embodiment 17

[0092] The preparation process is basically the same as that of Example 1, except that: in step S4, the duration of the second heating treatment is greater than 35 minutes, which will cause the final thickness of the TGO film to be too large, and the thermal barrier coating will be affected by thermal fatigue during its service, resulting in premature peeling of the coating.

[0093] Embodiment 18

[0094] The preparation process is basically the same as that of Example 1, except that: in step S4, the cooling rate during the cooling process from the first heat treatment to the second preset temperature heat treatment is greater than 20°C / s, which will cause the TGO film to peel off.

[0095] Embodiment 19

[0096] The preparation process is basically the same as that of Example 1, except that: in step S4, the cooling rate during the heat treatment from the first heat treatment to the second preset temperature is less than 10°C / s, which will cause the TGO film growth thickness to be too high, and the thermal barrier coating will be affected by thermal fatigue during its service, resulting in premature peeling of the coating.

[0097] In summary, according to Examples 1-19, the optimal heating rate for the first heat treatment is 50°C / s to 80°C / s, the first preset temperature is 1100°C to 1200°C, and the time is 5min to 10min. The optimal cooling rate for the second heat treatment is 10 to 20°C / s, the second preset temperature is 850°C to 1050°C, and the time is 20min to 35min. Under the above conditions, a thermal barrier coating comprising only α-Al2O3-based TGO film can be obtained.

[0098] The present invention provides a method for preparing a thermal barrier coating α-Al2O3 thermal growth oxide, which has the following beneficial effects compared with the prior art:

[0099] 1) The preparation process of the present invention is simple and the production difficulty is reduced. In order to produce an α-Al2O3-based TGO film on the surface of the bonding layer, only a segmented rapid temperature increase heat treatment method is required, which can be achieved in an atmospheric environment without the need for extremely high vacuum or high-purity inert atmosphere furnace for heat treatment.

[0100] 2) The heat treatment time of the present invention is usually less than 45 minutes, which greatly shortens the treatment time and reduces the production cost compared to the current heat treatment time which usually takes several hours to more than ten hours.

[0101] 3) The method of the present invention can directly obtain an α-Al2O3-based TGO film with a thickness of 1.0 μm to 2 μm, inhibiting the production of other non-α-Al2O3-based TGOs, effectively improving the bonding strength between the bonding layer and the ceramic coating, the antioxidant ability, preventing the coating from failing prematurely, and meeting the technical requirements for pre-oxidation of thermal barrier coatings for gas turbine blades.

[0102] It is to be understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present invention, but the present invention is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A method for preparing a thermal barrier coating α-Al2O3 thermally grown oxide, characterized in that: The preparation method comprises: Prepare an MCrAlY bonding layer on the surface of the sample; Cleaning the surface of the MCrAlY bonding layer; Heating the cleaned MCrAlY bonding layer to a first preset temperature at a heating rate of 50°C / s to 80°C / s to form an α-Al2O3-based TGO film of a first thickness on the surface of the MCrAlY bonding layer; The temperature is lowered to a second preset temperature, and the MCrAlY bonding layer is subjected to a second heat treatment, so that the α-Al2O3-based TGO film on the surface of the MCrAlY bonding layer continues to grow to a second thickness.

2. The method for preparing the thermal barrier coating α-Al2O3 thermal growth oxide according to claim 1, characterized in that: The first preset temperature is 1100°C to 1200°C.

3. The method for preparing the thermal barrier coating α-Al2O3 thermal growth oxide according to claim 1, characterized in that: The first heating treatment time is 5min to 10min.

4. The method for preparing the thermal barrier coating α-Al2O3 thermal growth oxide according to claim 1, characterized in that: The first thickness is 0.4-0.8 μm.

5. The method for preparing the thermal barrier coating α-Al2O3 thermal growth oxide according to claim 1, characterized in that: The cooling rate is 10-20℃ / s.

6. The method for preparing the thermal barrier coating α-Al2O3 thermal growth oxide according to claim 1, characterized in that: The second preset temperature is 850°C to 1050°C.

7. The method for preparing the thermal barrier coating α-Al2O3 thermal growth oxide according to claim 1, characterized in that: The second heating treatment time is 20min to 35min.

8. The method for preparing the thermal barrier coating α-Al2O3 thermal growth oxide according to claim 1, characterized in that: The second thickness is 1.0 μm to 2 μm.

9. The method for preparing the thermal barrier coating α-Al2O3 thermal growth oxide according to any one of claims 1 to 8, characterized in that: The cleaned MCrAlY bonding layer is subjected to a first heating treatment and a second heating treatment by using a flame heating method or an induction heating method.

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