A thermal barrier coating system and a method of making and using the same

Abstract

The present application relates to a kind of thermal barrier coating systems and its preparation method and application, which includes sequentially from inside to outside: adhesive layer, transition layer and ceramic thermal barrier layer, the transition layer includes NiCoCrAlY and RETa3O9.The present application can effectively control the thermal expansion coefficient of transition layer by setting transition layer to be composed of specific proportion of NiCoCrAlY and RETa3O9, make the thermal expansion coefficient of transition layer match with adhesive layer and ceramic thermal barrier layer;While the bonding strength between ceramic thermal barrier layer and adhesive layer is greatly improved after the preparation of mixed uniform transition layer by air plasma spraying, the bonding strength of thermal barrier coating system is greatly improved, thereby prolonging the service life of ceramic thermal barrier layer, oxidation resistance and gas hot scouring resistance.

Description

Technical Field

[0001] This invention relates to the field of coating technology, specifically to a thermal barrier coating system, its preparation method, and its application. Background Technology

[0002] Ceramic thermal barrier coatings are deposited on the surface of high-temperature resistant metals or superalloys to insulate the substrate material, reducing its temperature and enabling devices (such as engine turbine blades) to operate at high temperatures. They also improve the thermal efficiency of devices (such as engines). Ceramic thermal barrier coatings are widely used on the surfaces of high-temperature components in the combustion chambers of gas turbines, aero engines, and hypersonic vehicles to provide thermal insulation and cooling, and to extend the service life of hot-end components.

[0003] Most high-temperature alloy parts use magnesium alloy as the base material. A ceramic thermal barrier coating is prepared on the surface of the magnesium alloy parts by atmospheric plasma spraying to improve their operating temperature. However, the bonding strength between the ceramic thermal barrier coating and the magnesium alloy base is weak (less than 10 MPa), and the ceramic thermal barrier coating is prone to peeling and failure during service.

[0004] To address the technical problem of weak bonding strength (less than 10 MPa) between the ceramic thermal barrier coating (CBT) and the magnesium alloy substrate, leading to easy peeling and failure of the CBT during service, an adhesive layer is typically prepared between the CBT and the substrate to improve the bonding strength (reaching 20-30 MPa). However, with the increase in combustion chamber operating temperature and blade rotation speed, higher requirements are placed on the bonding strength of the CBT. The bonding strength between the CBT and the magnesium alloy substrate directly affects its service life. Therefore, how to improve the bonding strength between the magnesium alloy surface and the CBT is an urgent problem to be solved. Furthermore, under high-temperature conditions, oxygen in the air penetrates the coating and reacts with the magnesium alloy to form magnesium oxide on its surface. Due to the significant difference in thermal expansion coefficients between magnesium oxide, the magnesium alloy, and the adhesive layer alloy, the CBT may peel off and fail. Summary of the Invention

[0005] One objective of this invention is to provide a thermal barrier coating system to address the increasing demands on the bonding strength of ceramic thermal barrier coatings as combustion chamber operating temperatures and blade rotation speeds increase. The bonding strength between the ceramic thermal barrier coating and the magnesium alloy substrate directly affects its service life. Therefore, improving the bonding strength between the magnesium alloy surface and the ceramic thermal barrier coating is a pressing issue. Furthermore, at high temperatures, oxygen in the air penetrates the coating and reacts with the magnesium alloy to form magnesium oxide on its surface. Due to the significant difference in thermal expansion coefficients between magnesium oxide, the magnesium alloy, and the bonding layer alloy, this leads to technical problems such as the peeling and failure of the ceramic thermal barrier coating. A second objective is to provide a method for preparing the aforementioned thermal barrier coating system. A third objective is to provide the application of the aforementioned thermal barrier coating system or the thermal barrier coating system prepared according to the aforementioned method in aero-engines or gas turbines.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] In a first aspect, this application provides a thermal barrier coating system, which comprises, from the inside out, an adhesive layer, a transition layer and a ceramic thermal barrier layer, wherein the transition layer comprises NiCoCrAlY and RETa3O9.

[0008] Optionally, in the transition layer, the mass ratio of NiCoCrAlY to RETa3O9 is 12-25:75-88, preferably 15-25:75-85.

[0009] Optionally, the total thickness of the adhesive layer and the transition layer is 150-200 μm.

[0010] Optionally, the thickness of the transition layer is 80-120 μm.

[0011] Optionally, the adhesive layer comprises NiCoCrAlY.

[0012] Optionally, the ceramic thermal barrier layer comprises RETa3O9 spherical powder, wherein RE is at least one of Y, La, Pr, Nd, Sm, Eu, Gd, Dy, Ho and Tm.

[0013] Optionally, the particle size of the RETa3O9 spherical powder is 50-100 μm.

[0014] Optionally, the thickness of the ceramic thermal barrier layer is 200-300 μm.

[0015] Optionally, the ceramic thermal barrier layer further includes Ta nanoparticles.

[0016] Optionally, the mass ratio of the Ta nanoparticles to the RETa3O9 spherical powders is 3-8:100, preferably 5-8:100.

[0017] Optionally, the particle size of the Ta nanoparticles is ≤10nm.

[0018] Secondly, the present invention also provides a method for preparing the thermal barrier coating system as described above, comprising:

[0019] The surface of the metal substrate was rubbed with sandpaper, and then an adhesive layer, a transition layer and a ceramic thermal barrier layer were sequentially sprayed onto the rubbed metal substrate surface using atmospheric plasma spraying.

[0020] Optionally, the sandpaper has a grit size ≤ 100 mesh.

[0021] Optionally, during the application of the adhesive layer, the spray gun power is 30-40kW, preferably 35-40kW; the spray gun distance is 150-180mm, preferably 150-170mm; the feed rate is 50-80g / min, preferably 55-75g / min; the spray gun speed is 500-600mm / s, preferably 520-600mm / s; and the spraying time is 0.5-1.5min, preferably 0.8-1.3min.

[0022] Optionally, during the spraying of the transition layer, the spray gun power is 30-40kW, preferably 35-40kW; the spray gun distance is 150-180mm, preferably 150-170mm; the feed rate is 20-40g / min, preferably 25-35g / min; the spray gun speed is 300-400mm / s, preferably 300-320mm / s; and the spraying time is 0.5-1.5min, preferably 0.8-1.3min.

[0023] Optionally, during the process of spraying the ceramic thermal barrier layer, the spray gun power is 40-50kW, preferably 42-48kW; the spray gun distance is 200-300mm, preferably 250-300mm; the feed rate is 30-40g / min, preferably 35-40g / min; the spray gun speed is 400-500mm / s, preferably 420-480mm / s; and the spraying time is 1-3min, preferably 1.5-2.5min.

[0024] Thirdly, the present invention also provides the application of the thermal barrier coating system as described above or the thermal barrier coating system prepared according to the preparation method described above in aero engines or gas turbines.

[0025] The beneficial effects of this invention are as follows:

[0026] This invention improves the surface roughness of the metal substrate by rubbing it with sandpaper, eliminating the need for the commonly used sandblasting process and increasing the bonding strength between the adhesive layer and the magnesium alloy.

[0027] This invention effectively controls the thermal expansion coefficient of the transition layer by setting it to consist of a specific ratio of NiCoCrAlY and RETa3O9, making the thermal expansion coefficient of the transition layer match that of the adhesive layer and the ceramic thermal barrier layer. At the same time, the uniformly mixed transition layer, after being prepared by atmospheric plasma spraying, significantly improves the bonding strength between the ceramic thermal barrier layer and the adhesive layer, thereby greatly improving the bonding strength of the thermal barrier coating system, thus extending the service life, thermal fatigue resistance, and thermal erosion performance of the ceramic thermal barrier layer.

[0028] In this invention, the coefficient of thermal expansion of RETa3O9 is 5 × 10⁻⁶. -6 K -1 -10×10 -6 K -1 The coefficient of thermal expansion of NiCoCrAlY is 14 × 10⁻⁶. -6 K -1 -16×10 -6 K -1 The coefficient of thermal expansion of the magnesium alloy substrate is 12×10⁻⁶. -6 K -1 -14×10 -6 K -1 Therefore, using NiCoCrAlY as the binder material can eliminate the mismatch in thermal expansion coefficients between the magnesium alloy substrate and the binder, and improve the bonding strength between the two. Using RETa3O9+NiCoCrAlY composite coating as a transition layer can effectively alleviate the mismatch in thermal expansion coefficients between the ceramic thermal barrier layer and the binder. At the same time, preparing the coating by atmospheric plasma spraying can improve the metallurgical bonding between layers, and significantly improve the bonding strength between the binder, transition layer and ceramic thermal barrier layer, thereby obtaining a thermal barrier coating system with high bonding strength and long life.

[0029] In this invention, by adding Ta nanoparticles to the ceramic thermal barrier coating, its coefficient of thermal expansion can be effectively increased to match that of the transition layer. At the same time, using metallic Ta as a binder between RETa3O9 ceramic layers can effectively fill the gaps between layers, thereby reducing the porosity of the coating. When Ta is oxidized at high temperature to form tantalum oxide (Ta2O5), it can effectively fill the gaps between ceramic layers, thereby preventing oxygen in the air from entering the interior of the coating through the gaps and reacting with the magnesium alloy and the binder layer to form magnesium oxide, which greatly improves the oxidation resistance of the coating.

[0030] The thermal barrier coating system of the present invention has the characteristics of bonding strength higher than 40MPa, oxidation resistance and resistance to gas thermal shock. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the thermal barrier coating system of the present invention;

[0032] Figure 2 The image shows an electron microscope scan of the thermal barrier coating system prepared in Example 1.

[0033] Figure 3 To combine the strength test results diagram;

[0034] Figure 4 The image shows the results of the porosity test.

[0035] Figure 5 The graph shows the results of the oxidation weight gain rate test. Detailed Implementation

[0036] The present invention will be further illustrated by specific examples below. However, it should be noted that the specific material ratios, process conditions and results described in the embodiments of the present invention are only for illustrating the present invention and cannot be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

[0037] like Figure 1 As shown, this application provides a thermal barrier coating system, which comprises, from the inside out: a bonding layer (i.e., a metal bonding layer), a transition layer (i.e., a composite transition layer) with a thickness of 80-120 μm, and a ceramic thermal barrier layer (i.e., a ceramic thermal barrier coating) with a thickness of 200-300 μm. The transition layer comprises NiCoCrAlY and RETa3O9. In the transition layer, the mass ratio of NiCoCrAlY to RETa3O9 is 12-25:75-88. The total thickness of the bonding layer and the transition layer is 150-200 μm. The bonding layer of the transition layer comprises NiCoCrAlY, and the ceramic thermal barrier layer comprises spherical RETa3O9 powder with a particle size of 50-100 μm and Ta nanoparticles with a particle size ≤10 nm. RE is at least one of Y, La, Pr, Nd, Sm, Eu, Gd, Dy, Ho, and Tm. The mass ratio of Ta nanoparticles to spherical RETa3O9 powder is 3-8:100.

[0038] The present invention also provides a method for preparing the thermal barrier coating system as described above, comprising:

[0039] The surface of the metal substrate is abraded using sandpaper with a grit size ≤100. Then, an adhesive layer is applied to the abraded metal substrate surface using atmospheric plasma spraying at a spray gun power of 30-40kW, a spray gun distance of 150-180mm, a feed rate of 50-80g / min, and a spray gun speed of 500-600mm / s. The spraying time is 0.5-1.5min. Following this, atmospheric plasma spraying is performed again at a spray gun power of 30-40kW. For the transition layer, the spray gun distance is 150-180mm, the feed rate is 20-40g / min, and the spray gun speed is 300-400mm / s, with a spraying time of 0.5-1.5min. Then, the ceramic thermal barrier layer is sprayed using atmospheric plasma spraying with a spray gun power of 40-50kW, a spray gun distance of 200-300mm, a feed rate of 30-40g / min, and a spray gun speed of 400-500mm / s, with a spraying time of 1-3min.

[0040] The present invention also provides the application of the thermal barrier coating system as described above or the thermal barrier coating system prepared according to the preparation method described above in aero engines or gas turbines, and has the characteristics of coating bonding strength higher than 40MPa and resistance to gas thermal shock (resistance to more than 500 cycles of gas thermal shock at 1300°C).

[0041] The present invention will be described in detail below through specific examples and embodiments. It should also be understood that the following embodiments are only for specific illustration of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention are within the scope of protection of the present invention. The specific process parameters, etc., in the following examples are merely examples within a suitable range; that is, those skilled in the art can make appropriate selections within the appropriate range based on the description herein, and are not intended to be limited to the specific values ​​in the examples below.

[0042] Example 1

[0043] A thermal barrier coating system, the specific preparation process of which is as follows:

[0044] The magnesium alloy surface was rubbed with 100-grit sandpaper to form uniform scratches visible to the naked eye. Then, an atmospheric plasma spraying method was used to prepare a NiCoCrAlY bonding layer on the rubbed magnesium alloy. The spray gun power was 38kW, the spray gun distance was 160mm, the flow rates of argon and hydrogen were 32 / 12slpm and 38 / 15slpm, respectively, the feed rate was 56g / min, the spray gun speed was 550mm / s, the spraying time was 1min, and the bonding layer thickness was 50μm.

[0045] Subsequently, an atmospheric plasma spraying method was used to prepare a transition layer on the surface of the adhesive layer. The raw materials consisted of NiCoCrAlY and YTa3O9 in a mass ratio of 12:88. The spray gun power was 38kW, the spray gun distance was 160mm, the flow rates of argon and hydrogen were 46 / 11slpm and 52 / 13slpm, respectively, the feed rate was 30g / min, the spray gun speed was 320mm / s, the spraying time was 1min, and the thickness of the transition layer was 100μm.

[0046] A ceramic thermal barrier layer was then prepared on the surface of the transition layer using atmospheric plasma spraying. The raw materials consisted of YTa3O9 spherical powder with an average particle size of 50 μm and Ta nanoparticles with an average particle size of 10 nm. The mass ratio of Ta nanoparticles to YTa3O9 spherical powders was 3:100. The spray gun power was 45 kW, the spray gun distance was 260 mm, the flow rates of argon and hydrogen were 48 / 12 slpm and 40 / 10 slpm, respectively, the feed rate was 40 g / min, the spray gun speed was 450 mm / s, the spraying time was 2 min, and the thickness of the ceramic thermal barrier layer was 200 μm, thus obtaining the thermal barrier coating system.

[0047] The thermal barrier coating system prepared in this embodiment was scanned by electron microscopy, and the results are as follows: Figure 2 As shown.

[0048] Depend on Figure 2 As can be seen, in this embodiment, from bottom to top, are a magnesium alloy substrate, an adhesive layer, a transition layer (i.e., a composite transition layer), and a ceramic thermal barrier layer (i.e., a ceramic thermal barrier coating).

[0049] Example 2

[0050] A thermal barrier coating system, the specific preparation process of which is as follows:

[0051] The magnesium alloy surface was rubbed with 100-grit sandpaper to form uniform scratches visible to the naked eye. Then, an atmospheric plasma spraying method was used to prepare a NiCoCrAlY bonding layer on the rubbed magnesium alloy. The spray gun power was 36kW, the spray gun distance was 160mm, the flow rates of argon and hydrogen were 32 / 12slpm and 38 / 15slpm, respectively, the feed rate was 65g / min, the spray gun speed was 550mm / s, the spraying time was 1.2min, and the bonding layer thickness was 60μm.

[0052] Subsequently, an atmospheric plasma spraying method was used to prepare a transition layer on the surface of the adhesive layer. The raw materials consisted of NiCoCrAlY and HoTa3O9 in a mass ratio of 20:80. The spray gun power was 38kW, the spray gun distance was 160mm, the flow rates of argon and hydrogen were 46 / 11slpm and 52 / 13slpm, respectively, the feed rate was 30g / min, the spray gun speed was 320mm / s, the spraying time was 1.5min, and the thickness of the transition layer was 120μm.

[0053] A ceramic thermal barrier layer was then prepared on the surface of the transition layer using atmospheric plasma spraying. The raw materials consisted of HoTa3O9 spherical powder with an average particle size of 100 μm and Ta nanoparticles with an average particle size of 6 nm. The mass ratio of Ta nanoparticles to HoTa3O9 spherical powders was 8:100. The spray gun power was 45 kW, the spray gun distance was 260 mm, the flow rates of argon and hydrogen were 48 / 12 slpm and 40 / 10 slpm, respectively, the feed rate was 38 g / min, the spray gun speed was 450 mm / s, the spraying time was 3 min, and the thickness of the ceramic thermal barrier layer was 300 μm, thus obtaining the thermal barrier coating system.

[0054] Example 3

[0055] A thermal barrier coating system, the specific preparation process of which is as follows:

[0056] The magnesium alloy surface was rubbed with 100-grit sandpaper to form uniform scratches visible to the naked eye. Then, an atmospheric plasma spraying method was used to prepare a NiCoCrAlY bonding layer on the rubbed magnesium alloy. The spray gun power was 40kW, the spray gun distance was 160mm, the flow rates of argon and hydrogen were 32 / 12slpm and 38 / 15slpm, respectively, the feed rate was 60g / min, the spray gun speed was 580mm / s, the spraying time was 1.8min, and the bonding layer thickness was 80μm.

[0057] Subsequently, an atmospheric plasma spraying method was used to prepare a transition layer on the surface of the adhesive layer. The raw materials consisted of NiCoCrAlY and EuTa3O9 in a mass ratio of 25:75. The spray gun power was 37kW, the spray gun distance was 160mm, the flow rates of argon and hydrogen were 46 / 11slpm and 52 / 13slpm, respectively, the feed rate was 31g / min, the spray gun speed was 320mm / s, the spraying time was 1min, and the thickness of the transition layer was 80μm.

[0058] A ceramic thermal barrier layer was then prepared on the surface of the transition layer using atmospheric plasma spraying. The raw materials consisted of EuTa3O9 spherical powder with an average particle size of 95 μm and Ta nanoparticles with an average particle size of 7 nm. The mass ratio of Ta nanoparticles to EuTa3O9 spherical powders was 5:100. The spray gun power was 47 kW, the spray gun distance was 260 mm, the flow rates of argon and hydrogen were 48 / 12 slpm and 40 / 10 slpm, respectively, the feed rate was 38 g / min, the spray gun speed was 450 mm / s, the spraying time was 2.5 min, and the thickness of the ceramic thermal barrier layer was 220 μm, thus obtaining the thermal barrier coating system.

[0059] Example 4

[0060] A thermal barrier coating system, the specific preparation process of which is as follows:

[0061] The magnesium alloy surface was rubbed with 100-grit sandpaper to form uniform scratches visible to the naked eye. Then, an atmospheric plasma spraying method was used to prepare a NiCoCrAlY bonding layer on the rubbed magnesium alloy. The spray gun power was 35kW, the spray gun distance was 160mm, the flow rates of argon and hydrogen were 32 / 12slpm and 38 / 15slpm, respectively, the feed rate was 50g / min, the spray gun speed was 550mm / s, the spraying time was 2min, and the bonding layer thickness was 70μm.

[0062] Subsequently, an atmospheric plasma spraying method was used to prepare a transition layer on the surface of the adhesive layer. The raw materials consisted of NiCoCrAlY and GdTa3O9 in a mass ratio of 18:82. The spray gun power was 35kW, the spray gun distance was 160mm, the flow rates of argon and hydrogen were 46 / 11slpm and 52 / 13slpm, respectively, the feed rate was 35g / min, the spray gun speed was 320mm / s, the spraying time was 2min, and the thickness of the transition layer was 95μm.

[0063] A ceramic thermal barrier layer was then prepared on the surface of the transition layer using atmospheric plasma spraying. The raw materials consisted of GdTa3O9 spherical powder with an average particle size of 85 μm and Ta nanoparticles with an average particle size of 5 nm. The mass ratio of Ta nanoparticles to GdTa3O9 spherical powders was 6:100. The spray gun power was 47 kW, the spray gun distance was 240 mm, the flow rates of argon and hydrogen were 48 / 12 slpm and 40 / 10 slpm, respectively, the feed rate was 41 g / min, the spray gun speed was 420 mm / s, the spraying time was 3 min, and the thickness of the ceramic thermal barrier layer was 285 μm, thus obtaining the thermal barrier coating system.

[0064] Example 5

[0065] A thermal barrier coating system, the specific preparation process of which is as follows:

[0066] The magnesium alloy surface was rubbed with 100-grit sandpaper to form uniform scratches visible to the naked eye. Then, an atmospheric plasma spraying method was used to prepare a NiCoCrAlY bonding layer on the rubbed magnesium alloy. The spray gun power was 40kW, the spray gun distance was 160mm, the flow rates of argon and hydrogen were 32 / 12slpm and 38 / 15slpm, respectively, the feed rate was 60g / min, the spray gun speed was 550mm / s, the spraying time was 2min, and the bonding layer thickness was 90μm.

[0067] Subsequently, an atmospheric plasma spraying method was used to prepare a transition layer on the surface of the adhesive layer. The raw materials consisted of NiCoCrAlY and LaTa3O9 in a mass ratio of 23:77. The spray gun power was 38kW, the spray gun distance was 160mm, the flow rates of argon and hydrogen were 46 / 11slpm and 52 / 13slpm, respectively, the feed rate was 30g / min, the spray gun speed was 320mm / s, the spraying time was 1min, and the thickness of the transition layer was 110μm.

[0068] A ceramic thermal barrier layer was then prepared on the surface of the transition layer using atmospheric plasma spraying. The raw materials consisted of LaTa3O9 spherical powder with an average particle size of 100 μm and Ta nanoparticles with an average particle size of 10 nm. The mass ratio of Ta nanoparticles to LaTa3O9 spherical powders was 7:100. The spray gun power was 49 kW, the spray gun distance was 260 mm, the flow rates of argon and hydrogen were 48 / 12 slpm and 40 / 10 slpm, respectively, the feed rate was 38 g / min, the spray gun speed was 410 mm / s, the spraying time was 3 min, and the thickness of the ceramic thermal barrier layer was 216 μm, thus obtaining the thermal barrier coating system.

[0069] Example 6

[0070] A thermal barrier coating system, the specific preparation process of which is as follows:

[0071] The magnesium alloy surface was rubbed with 100-grit sandpaper to form uniform scratches visible to the naked eye. Then, an atmospheric plasma spraying method was used to prepare a NiCoCrAlY bonding layer on the rubbed magnesium alloy. The spray gun power was 38kW, the spray gun distance was 160mm, the flow rates of argon and hydrogen were 32 / 12slpm and 38 / 15slpm, respectively, the feed rate was 70g / min, the spray gun speed was 510mm / s, the spraying time was 2min, and the bonding layer thickness was 100μm.

[0072] Subsequently, an atmospheric plasma spraying method was used to prepare a transition layer on the surface of the adhesive layer. The raw materials consisted of NiCoCrAlY and DyTa3O9 in a mass ratio of 16:84. The spray gun power was 39kW, the spray gun distance was 170mm, the flow rates of argon and hydrogen were 46 / 11slpm and 52 / 13slpm, respectively, the feed rate was 33g / min, the spray gun speed was 320mm / s, the spraying time was 2min, and the thickness of the transition layer was 100μm.

[0073] A ceramic thermal barrier layer was then prepared on the surface of the transition layer using atmospheric plasma spraying. The raw materials consisted of DyTa3O9 spherical powder with an average particle size of 70 μm and Ta nanoparticles with an average particle size of 8 nm. The mass ratio of Ta nanoparticles to DyTa3O9 spherical powders was 4:100. The spray gun power was 45 kW, the spray gun distance was 260 mm, the flow rates of argon and hydrogen were 48 / 12 slpm and 40 / 10 slpm, respectively, the feed rate was 38 g / min, the spray gun speed was 450 mm / s, the spraying time was 3 min, and the thickness of the ceramic thermal barrier layer was 275 μm, thus obtaining the thermal barrier coating system.

[0074] Comparative Example 1

[0075] The difference between this comparative example and Example 1 is that the raw materials used in the preparation of the transition layer consist of NiCoCrAlY and DyTa3O9 in a mass ratio of 30:70. The excessively high mass fraction of NiCoCrAlY alloy powder results in a larger amount of NiCoCrAlY being oxidized in the transition layer after spraying. This leads to the formation of a larger oxide film within the transition layer, increasing internal thermal stress and hindering the improvement of its bonding strength and service life. Simultaneously, the thermal expansion coefficient of the transition layer is significantly higher than that of the outermost ceramic thermal barrier coating, making cracking between the two coatings more likely.

[0076] Comparative Example 2

[0077] The difference between this comparative example and Example 1 is that no transition layer was prepared, that is, the ceramic thermal barrier coating was directly prepared on the surface of the adhesive layer, which resulted in a mismatch in the coefficient of thermal expansion between the ceramic thermal barrier coating and the adhesive layer, thereby causing the ceramic coating to crack and peel off from the interface.

[0078] Comparative Example 3

[0079] The difference between this comparative example and Example 1 is that the raw material used in the preparation of the ceramic thermal barrier layer is YTa3O9 spherical powder with an average particle size of 50μm. That is, the raw material used in the preparation of the ceramic thermal barrier layer does not contain Ta nanoparticles. After the coating is sprayed, it cannot effectively fill the voids inside the coating and it is difficult to improve the bonding strength of the transition layer. Therefore, the oxygen barrier performance and bonding strength of the prepared coating are insufficient, and it cannot achieve the features and functions described in this patent application.

[0080] Comparative Example 4

[0081] The difference between this comparative example and Example 1 is that: during the preparation of the ceramic thermal barrier layer, sandpaper was not used to pretreat the surface of the alloy substrate, which will result in insufficient surface roughness of the magnesium alloy and low bonding strength between the adhesive layer and the alloy substrate after direct spraying of the coating.

[0082] Performance testing

[0083] The bonding strength between the ceramic thermal barrier layer and the adhesive layer in the thermal barrier coating systems prepared in Examples 1-6 and Comparative Examples 1-2 was tested. The testing steps were as follows: The bonding strength was tested using a tensile testing machine. Before the test, the upper and lower surfaces of the circular sample for preparing the coating were firmly bonded to the upper and lower tensile bars of the tensile testing machine using strong adhesive. The tensile stress was gradually increased until the coating separated from the alloy substrate. The ratio of the tensile force at separation to the area of ​​the alloy substrate was the bonding strength of the coating. The results are as follows. Figure 3 As shown in Table 1;

[0084] The porosity of the ceramic thermal barrier layer in the thermal barrier coating systems prepared in Examples 1-6 and Comparative Example 3 was detected. The detection steps were as follows: the microstructure of the ceramic coating cross-section was tested using a scanning electron microscope. The dark gray area represents pores and cracks within the coating, while the light-colored area represents the coating itself. The porosity of the ceramic coating was calculated based on the ratio of the area of ​​the dark gray region to the total area. The results are as follows. Figure 4 As shown in Table 1;

[0085] The oxidation weight gain rate of the ceramic thermal barrier layer in the thermal barrier coating systems prepared in Examples 1-6 and Comparative Example 3 was tested after holding at 1000℃ for 12 hours. The testing procedure was as follows: the surface coating of the prepared ceramic-coated magnesium alloy was heated to 1000℃ within 20 seconds using an acetylene + oxygen flame gun, and the temperature was measured using an infrared thermometer. After holding at 12 hours, the masses of the coated magnesium alloy before and after the test were compared as W1 and W2, respectively. The oxidation weight gain rate was calculated as ((W2-W1) / W1)*100%. The results are as follows. Figure 5 As shown in Table 1.

[0086] The resistance of the thermal barrier coating systems prepared in Examples 1-6 and Comparative Examples 1-2 to the number of gas thermal shocks was tested. The test steps were as follows: the surface coating of the prepared ceramic-coated magnesium alloy was heated to 1300°C within 20 seconds using an acetylene + oxygen flame gun, the temperature was measured using an infrared thermometer, and the temperature was held at 1300°C for 20 seconds. Then the heating chamber was removed, and the alloy substrate was cooled in the air for 20 seconds. This was considered one gas thermal shock. This process was repeated. When the area of ​​coating peeling off exceeded 10%, the coating was considered to have failed. The number of shocks at this time was recorded.

[0087] Table 1 Test Results

[0088]

[0089]

[0090] Note: -- indicates not detected.

[0091] Depend on Figure 3 As shown in Table 1, the bonding strengths of the thermal barrier coating systems prepared in Comparative Examples 1, 2, and 4 are 15 MPa, 16 MPa, and 8 MPa, respectively, while the bonding strengths of the thermal barrier coating systems prepared in Examples 1-6 are 46-55 MPa. Specifically, in Comparative Example 1, the addition of a very high amount of NiCoCrAlY results in a much higher coefficient of thermal expansion than the ceramic layer, leading to a large difference in thermal expansion coefficients and thus low bonding strength. In Comparative Example 2, the absence of a transition layer leads to a large difference in thermal expansion coefficients between the adhesive layer and the ceramic thermal barrier layer, resulting in weak bonding strength between the ceramic thermal barrier layer and the adhesive layer. In Comparative Example 3, the lack of pretreatment of the alloy surface results in low bonding strength between the coating and the alloy. These results indicate that the thermal barrier coating system prepared in this invention has stronger bonding strength.

[0092] Depend on Figure 4 As shown in Table 1, the porosity of the ceramic thermal barrier layer in the thermal barrier coating system prepared in Comparative Example 3 is 11.8%, while the porosity of the ceramic thermal barrier layer in the thermal barrier coating systems prepared in Examples 1-6 is 1.2%-2.6%. This result indicates that the ceramic thermal barrier layer in the thermal barrier coating system prepared by the present invention has a smaller porosity.

[0093] Depend on Figure 4 , Figure 5 As shown in Table 1, the oxidation weight gain of the ceramic thermal barrier layer in the thermal barrier coating system prepared in Comparative Example 3 was 23.9%, while the oxidation weight gain of the ceramic thermal barrier layer in the thermal barrier coating systems prepared in Examples 1-6 was 3%-6%. This indicates that the ceramic thermal barrier layer does not contain nano-tantalum powder, resulting in high porosity and weak oxidation resistance. These results demonstrate that the ceramic thermal barrier layer in the thermal barrier coating system prepared by this invention has lower porosity.

[0094] Table 1 shows that the samples prepared in Examples 1-6 have better resistance to gas thermal shock, with 510-632 tests; while the samples in Comparative Examples 1-4 have less than 200 gas thermal shock tests. This is because the coatings prepared in Examples 1-6 have better oxidation resistance and higher bonding strength.

[0095] The above embodiments are merely preferred embodiments provided to fully illustrate the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention.

Claims

1. A thermal barrier coating system, characterized in that, The thermal barrier coating system comprises, from inside to outside, a bonding layer, a transition layer and a ceramic thermal barrier layer, the transition layer comprises NiCoCrAlY and RETa3O9, the mass ratio of NiCoCrAlY to RETa3O9 is 12-25:75-88; the bonding layer comprises NiCoCrAlY, the ceramic thermal barrier layer comprises RETa3O9 spherical powder and Ta nano-powder, the mass ratio of the Ta nano-powder to the RETa3O9 spherical powder is 3-8:100; RE is at least one of Y, La, Pr, Nd, Sm, Eu, Gd, Dy, Ho and Tm.

2. The thermal barrier coating system of claim 1, wherein, The total thickness of the bonding layer and the transition layer is 150-200 μm.

3. The thermal barrier coating system of claim 2, wherein, The thickness of the transition layer is 80-120 μm.

4. The thermal barrier coating system of claim 1, wherein, The particle size of the RETa3O9 spherical powder is 50-100 μm. The thickness of the ceramic thermal barrier layer is 200-300 μm.

5. The thermal barrier coating system of claim 1, wherein, The particle size of the Ta nano-powder is ≤10 nm.

6. A method of producing the thermal barrier coating system according to any one of claims 1 to 5, characterized in that Comprising: The surface of the metal substrate is rubbed using sandpaper, and then the bonding layer, the transition layer and the ceramic thermal barrier layer are sprayed on the rubbed surface of the metal substrate in sequence by means of atmospheric plasma spraying.

7. The production method according to claim 6, wherein The particle size of the sandpaper is ≤100 mesh.

8. The production method according to claim 6, wherein During spraying of the bonding layer, the power of the spray gun is 30-40 kW, the spray gun distance is 150-180 mm, the feeding speed is 50-80 g / min, the spray gun speed is 500-600 mm / s, and the spraying time is 0.5-1.5 min; During spraying of the transition layer, the power of the spray gun is 30-40 kW, the spray gun distance is 150-180 mm, the feeding speed is 20-40 g / min, the spray gun speed is 300-400 mm / s, and the spraying time is 0.5-1.5 min; During spraying of the ceramic thermal barrier layer, the power of the spray gun is 40-50 kW, the spray gun distance is 200-300 mm, the feeding speed is 30-40 g / min, the spray gun speed is 400-500 mm / s, and the spraying time is 1-3 min.

9. The thermal barrier coating system of any one of claims 1-5 or the thermal barrier coating system prepared according to any one of claims 6-8 for use in an aero-engine or a gas turbine.

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