Thermal protection composite coating and preparation method and application thereof

Abstract

The application discloses a thermal protection composite coating and a preparation method and application thereof, and belongs to the technical field of thermal protection coatings. The thermal protection composite coating comprises a bottom layer and a surface layer arranged in sequence from inside to outside on the surface of a substrate. The elements contained in the bottom layer include M, Cr, Al and Y, and M includes at least one of Co and Ni. The elements contained in the surface layer include Al and Q, and Q includes at least one of Si, Y, Ce and Zr. The thickness of the bottom layer and the surface layer is independently not more than 40 microns, and the total thickness of the two is not more than 40 microns. The surface layer of the composite coating is rich in Al, which can provide sufficient Al source for the generation of continuous aluminum oxide on the surface of the coating, slow down the consumption of Al in the bottom layer, and provide good thermal protection performance. Furthermore, by setting the bottom layer and the surface layer according to the above element composition and thickness, the interdiffusion between the coating and the substrate can be weakened, the stability and reliability of the composite coating can be improved, and the composite coating can be applied to the hot end parts of an aero-engine or a gas turbine.

Description

Technical Field

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

[0002] As the thrust-to-weight ratio of aero engines or gas turbines continues to increase, they face increasingly harsh service environments. As a result, high-temperature protective coatings with superior thermal protection performance are needed.

[0003] Commonly used high-temperature protective coatings are those containing Al. However, current Al-containing high-temperature protective coatings are difficult to work stably for a long time at temperatures above 1100℃ and are prone to failure during service, resulting in insufficient high-temperature stability and reliability.

[0004] In view of this, the present invention is proposed. Summary of the Invention

[0005] The purpose of this invention is to provide a thermal protective composite coating, its preparation method, and its application, so as to solve or improve the above-mentioned technical problems.

[0006] This invention can be implemented as follows: In a first aspect, the present invention provides a thermal protective composite coating, the thermal protective composite coating comprising a base layer and a top layer disposed sequentially from the inside to the outside on the surface of a substrate; The bottom layer contains elements including M, Cr, Al, and Y, where M includes at least one of Co and Ni. By atomic percentage, Cr comprises 25%–35% of the bottom layer, Al comprises 8%–15%, and Y comprises 0.5%–5%. When M contains Co, the Co content in the bottom layer does not exceed 60%. When M contains Ni, the Ni content in the bottom layer does not exceed 60%. The surface layer contains Al and Q, where Q includes at least one of Si, Y, Ce, and Zr. The Al content in the surface layer is not less than 50% and less than 100% by atomic percentage. When Q contains Si, the Si content in the surface layer is 0.5% to 5%. When Q contains Y, the Y content in the surface layer is 0.5% to 5%. When Q contains Ce, the Ce content in the surface layer is 0.5% to 5%. When Q contains Zr, the Zr content in the surface layer is 0.5% to 5%. The thickness of the base layer and the top layer does not exceed 40 μm independently, and the total thickness of the base layer and the top layer does not exceed 40 μm.

[0007] In an optional embodiment, the content of Cr in the bottom layer is 28% to 35%, the content of Al in the bottom layer is 10% to 13%, and the content of Y in the bottom layer is 1% to 3%.

[0008] In an optional embodiment, the bottom layer also includes Z, which includes at least one of Ta, Hf and Si; by atomic percentage, when Z contains Ta, the content of Ta in the bottom layer is 0.5% to 5%; when Z contains Hf, the content of Hf in the bottom layer is 0.5% to 5%; when Z contains Si, the content of Si in the bottom layer does not exceed 8%.

[0009] In an optional implementation, the Si content in the bottom layer is 3% to 5%.

[0010] In an optional embodiment, the Si content in the surface layer is 4% to 5%, and the Y content in the surface layer is 1% to 2%.

[0011] In optional embodiments, the thermal protective composite coating also has at least one of the following characteristics: Feature 1: The average oxidation rate of the heat-protective composite coating after being oxidized at a constant temperature of 1150℃ for 300 hours does not exceed 0.1 g / (m²). 2 ·h); Feature 2: The thickness of the interdiffusion zone formed after the thermal protective composite coating is oxidized at 1150℃ for 300 hours does not exceed 90μm.

[0012] Secondly, the present invention provides a method for preparing a thermal protective composite coating as described in any of the foregoing embodiments, comprising the following steps: sequentially preparing a base layer and a top layer on the surface of a substrate.

[0013] In an optional embodiment, under the condition of an electromagnetic permanent magnet composite magnetic field, an underlayer and a top layer are sequentially deposited on the substrate surface by arc ion plating, followed by vacuum heat treatment.

[0014] In an optional implementation, after the bottom layer is deposited, the bottom layer is first cleaned before the top layer is deposited.

[0015] In an optional embodiment, the matrix is ​​a high-temperature alloy matrix, more preferably a Ni-based high-temperature alloy matrix.

[0016] In an optional implementation, during the deposition of the bottom layer, the conditions of the electromagnetic permanent magnet composite magnetic field include: electromagnetic voltage of 2.4V~50V, electromagnetic frequency of 1.0Hz~33.3Hz, and permanent magnet parameters of 5000Gs~15000Gs. The conditions for arc ion plating include: furnace pressure of 0.5 Pa to 3.5 Pa, temperature of 250 ℃ to 450 ℃, arc target current of 50 A to 120 A, substrate bias voltage of -50 V to -250 V, duty cycle of 70% to 90%, and deposition time not exceeding 300 min.

[0017] In an optional embodiment, the electromagnetic voltage is 4.8V to 50V.

[0018] In an optional embodiment, the pressure inside the furnace is 0.8 Pa to 2 Pa.

[0019] In an optional implementation, during the deposition of the surface layer, the conditions of the electromagnetic permanent magnet composite magnetic field include: electromagnetic voltage of 4.8V~50V, electromagnetic frequency of 1.0Hz~33.3Hz, and permanent magnet parameters of 5000Gs~15000Gs. The conditions for arc ion plating include: furnace pressure of 0.8 Pa to 2 Pa, temperature of 250 °C to 450 °C, arc target current of 50 A to 120 A, substrate bias voltage of -50 V to -250 V, duty cycle of 50% to 90%, and deposition time not exceeding 300 min.

[0020] In an optional embodiment, the substrate bias voltage is -10V to -250V; In an optional implementation, the duty cycle is 70% to 90%.

[0021] In an optional embodiment, the vacuum heat treatment temperature is 800℃~1100℃, and the treatment time is 2h~6h.

[0022] Thirdly, the present invention provides an application of a thermal protective composite coating as described in any of the foregoing embodiments, wherein the thermal protective composite coating is used to prepare hot-end components of an aero-engine or gas turbine.

[0023] The beneficial effects of this invention include: The thermal protective composite coating provided by the invention has an Al-rich top layer and a low-Al-content MCrAlY bottom layer. The Al-rich top layer can rapidly generate a relatively dense and continuous oxide layer under high-temperature conditions, providing an Al source for the continuous generation of continuous and dense Al2O3 on the surface. This effectively blocks oxygen from entering the coating interior, slows down the consumption of the bottom layer, and improves the coating's resistance to high-temperature oxidation. The bottom layer, as a transition layer between the top layer and the substrate, alleviates the large compositional difference between the top layer and the substrate, reduces the interdiffusion between the coating and the substrate, and reduces the precipitation of harmful TCP phases, thereby improving the coating's lifespan and stability. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 The image shows a cross-sectional SEM image of the thermal protective composite coating prepared in Example 2. Figure 2 The image shows a cross-sectional SEM image of the thermal protective composite coating prepared in Example 4. Figure 3 The image shows a cross-sectional SEM image of the thermal protective composite coating prepared in Comparative Example 3. Figure 4 The image shows a cross-sectional SEM image of the thermal protective composite coating prepared in Comparative Example 7. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0027] The following is a detailed description of the thermal protective composite coating, its preparation method, and its application provided by the present invention.

[0028] The present invention provides a thermal protective composite coating, which includes a base layer and a top layer disposed sequentially from the inside to the outside on the surface of a substrate.

[0029] The bottom layer contains elements including M, Cr, Al and Y, where M includes at least one of Co and Ni.

[0030] The Cr content in the underlayer, measured by atomic percentage, can be 25% to 35%, such as 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, or 35%, or other values ​​within the range of 25% to 35%. In some preferred embodiments, the Cr content in the underlayer is 28% to 35%. Cr mainly functions as an important component in the underlayer to stabilize the γ phase in the matrix and to resist corrosion or oxidation. If the Cr content in the underlayer is too low, it is not conducive to the formation of a protective oxide film during corrosion or oxidation; if the Cr content in the underlayer is too high, it is not conducive to the stability of the matrix phase.

[0031] The Al content in the substrate can be 8% to 15%, such as 8%, 9%, 10%, 11%, 12%, 13%, 14%, or 15%, or other values ​​within the range of 8% to 15%. In some preferred embodiments, the Al content in the substrate is 10% to 13%. If the Al content in the substrate is too low, it is not conducive to the formation of a complete Al2O3 film; if the Al content in the substrate is too high, it is not conducive to the stability of the matrix phase.

[0032] The content of Y in the substrate can be 0.5% to 5%, such as 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, or 5%, or other values ​​within the range of 0.5% to 5%. In some preferred embodiments, the content of Y in the substrate is 1% to 3%. Y mainly plays a role in improving the adhesion of the oxide film and changing the growth mechanism of the oxide film; if the content of Y in the substrate is too low, it is not conducive to improving the adhesion of the oxide coating layer; if the content of Y in the substrate is too high, it is not conducive to the continuity and density of the oxide film.

[0033] When M contains Co, the Co content in the underlayer should not exceed 60%, such as 60%, 50%, 40%, 30%, 20%, 10%, or 0%, or other values ​​within the range not exceeding 60%. If the Co content in the underlayer is too high, it will be detrimental to the high-temperature performance of the coating above 1000℃.

[0034] When M contains Ni, the Ni content in the underlayer should not exceed 60%, such as 60%, 50%, 40%, 30%, 20%, 10%, or 0%, or other values ​​within the range not exceeding 60%. If the Ni content in the underlayer is too high, it will be detrimental to the high-temperature performance of the coating at the service temperature.

[0035] Furthermore, the elements contained in the aforementioned underlying layer may also include Z, which may include at least one of Ta, Hf, and Si.

[0036] In terms of atomic percentage, when Z contains Ta, the content of Ta in the bottom layer can be 0.5% to 5%, such as 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5% or 5%, or other values ​​within the range of 0.5% to 5%.

[0037] When Z contains Hf, the content of Hf in the bottom layer can be 0.5% to 5%, such as 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5% or 5%, or other values ​​within the range of 0.5% to 5%.

[0038] When Z contains Si, the Si content in the bottom layer does not exceed 8%, such as 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0%, etc., or other values ​​not exceeding 8%. In some preferred embodiments, the Si content in the bottom layer is 3% to 5%.

[0039] By optimizing the composition of the MCrAlYZ layer according to the above scheme, the high-temperature oxidation resistance of the coating can be further improved, giving the coating excellent comprehensive performance.

[0040] In this invention, the elements contained in the surface layer include Al and Q, and Q may include at least one of Si, Y, Ce and Zr.

[0041] In terms of atomic percentage, the Al content in the surface layer should be no less than 50% and no more than 100%, such as 50%, 60%, 70%, 80%, 90%, 95%, or 99%, or other values ​​within the range of no less than 50% and no more than 100%. If the Al content in the surface layer is too low, it is not conducive to the formation of a continuous and dense Al2O3 layer in the coating.

[0042] When Q contains Si, the Si content in the surface layer can be 0.5% to 5%, such as 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, or 5%, or other values ​​within the range of 0.5% to 5%. In some preferred embodiments, the Si content in the surface layer is 4% to 5%.

[0043] When Q contains Y, the content of Y in the surface layer can be 0.5% to 5%, such as 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, or 5%, or other values ​​within the range of 0.5% to 5%. In some preferred embodiments, the content of Y in the surface layer is 1% to 2%.

[0044] When Q contains Ce, the Ce content in the surface layer can be 0.5% to 5%, such as 0.5%, 1%, 2%, 3%, 4% or 5%, or other values ​​within the range of 0.5% to 5%.

[0045] When Q contains Zr, the Zr content in the surface layer can be 0.5% to 5%, such as 0.5%, 1%, 2%, 3%, 4% or 5%, or other values ​​within the range of 0.5% to 5%.

[0046] In this invention, the thickness of the bottom layer does not exceed 40 μm, the thickness of the top layer also does not exceed 40 μm, and the total thickness of the bottom layer and the top layer does not exceed 40 μm. In some preferred embodiments, the thickness ratio of the bottom layer to the top layer is 0.2:1 to 1:1.

[0047] It should be noted that the thickness of the base layer and the top layer needs to be within a suitable ratio range. If the base layer is too thin (the top layer is too thick), the Al atoms in the top layer can easily diffuse through the base layer into the substrate, and the base layer will not play a role in mitigating the interdiffusion between the coating and the substrate. If the base layer is too thick (the top layer is too thin), the top layer will easily become too thin and will not be able to provide an Al source.

[0048] In some optional embodiments, the average oxidation rate of the thermally protective composite coating provided by the present invention, after being oxidized at a constant temperature of 1150°C for 300 hours, does not exceed 0.1 g / (m²). 2•h), further not exceeding 0.065g / (m 2 ·h), such as 0.0386g / (m 2 ·h)~0.0631g / (m 2 ·h).

[0049] In some optional embodiments, the thickness of the interdiffusion zone formed by the thermal protective composite coating provided by the present invention after constant temperature oxidation at 1150°C for 300 hours does not exceed 90 μm, such as 50 μm to 90 μm.

[0050] It should be noted that conventional MCrAlY coatings, due to their limited Al content, are difficult to maintain stable operation for extended periods above 1100℃. However, excessively high Al content can increase the coating's brittleness, making it prone to failure during service. Furthermore, the significant compositional difference between high-Al content coatings and the substrate can cause severe interdiffusion between the coating and the substrate, leading to the formation of harmful brittle TCP phases at the coating-substrate interface, severely impacting the stability and reliability of engines and gas turbines. The thermal protective composite coating provided by this invention has an Al-rich top layer and a low-Al content MCrAlY bottom layer. The Al-rich layer can rapidly form a relatively dense and continuous oxide layer under high-temperature conditions, effectively preventing oxygen from entering the coating interior, slowing down coating consumption, and extending the coating's service life. The bottom MCrAlY layer mitigates the elemental compositional difference between the Al-rich layer and the substrate, reducing interdiffusion between the coating and the substrate and decreasing the formation of brittle and harmful TCP phases, thereby improving the coating's stability and reliability.

[0051] Accordingly, the present invention also provides a method for preparing the above-mentioned thermal protective composite coating, comprising the following steps: preparing a base layer and a top layer sequentially on the surface of a substrate.

[0052] The matrix can be a high-temperature alloy matrix, such as a Ni-based high-temperature alloy matrix, to prepare a high-temperature resistant material.

[0053] Before depositing the substrate, the substrate is pretreated, such as by surface polishing, ultrasonic cleaning, and sandblasting. The pretreated sample is then dried in an incubator at a temperature of 100°C to 200°C.

[0054] In this invention, the thermal protective composite coating is prepared by depositing an underlayer and a toplayer sequentially on the substrate surface using an electric arc ion plating method under an electromagnetic permanent magnet composite magnetic field, followed by vacuum heat treatment.

[0055] By sequentially depositing a base layer and a top layer on a substrate, a composite coating material with both good high-temperature oxidation resistance and low interdiffusion can be obtained.

[0056] In some alternative implementations, after the bottom layer is deposited, the bottom layer is first cleaned (e.g., by high-energy particle surface cleaning) before the top layer is deposited.

[0057] In this invention, the substrate is subjected to high-bias ion cleaning before the underlayer is deposited; and the underlayer is subjected to metal ion cleaning before the toplayer is deposited. By applying high-bias bombardment, high-energy argon ions and metal ions are used to clean the adsorbed atoms on the surface, thereby improving the quality of the composite coating. Without surface cleaning, there will be obvious black delamination between the deposited layer and the substrate, mainly composed of aluminum oxide, which will seriously affect the bonding strength between the coating and the substrate, leading to easy peeling of the coating and severely affecting its performance and lifespan.

[0058] In some optional embodiments, during the deposition of the underlying layer, the conditions of the electromagnetic-permanent magnet composite magnetic field include: an electromagnetic voltage of 2.4V~50V (e.g., 2.4V, 3.6V, 4.8V, 5V, 10V, 20V, 30V, 40V, or 50V, preferably 4.8V~50V), an electromagnetic frequency of 1.0Hz~33.3Hz (e.g., 1Hz, 5Hz, 10Hz, 15Hz, 20Hz, 25Hz, 30Hz, or 33.3Hz), and permanent magnet parameters of 5000Gs~15000Gs (e.g., 5000Gs, 8000Gs, 10000Gs, 12000Gs, or 15000Gs). Preferably, the conditions of the electromagnetic-permanent magnet composite magnetic field include: an electromagnetic voltage of 4.8V, an electromagnetic frequency of 1.0Hz, and permanent magnet parameters of 1000Gs~15000Gs.

[0059] During the deposition of the bottom layer, the conditions for arc ion plating include: furnace pressure of 0.5 Pa to 3.5 Pa (e.g., 0.5 Pa, 0.8 Pa, 1 Pa, 1.5 Pa, 2 Pa, 2.5 Pa, 3 Pa, or 3.5 Pa, preferably 0.8 Pa to 2 Pa), temperature of 250℃ to 450℃ (e.g., 250℃, 300℃, 350℃, 400℃, or 450℃), arc target current of 50 A to 120 A (e.g., 50 A, 80 A, 100 A, or 120 A), substrate bias voltage of -50 V to -250 V (e.g., -50 V, -100 V, -150 V, -200 V, or -250 V), duty cycle of 70% to 90% (e.g., 70%, 75%, 80%, 85%, or 90%), and deposition time not exceeding 300 min. Preferably, the furnace pressure is 1 Pa to 2 Pa, the temperature is 250°C to 450°C, the arc target current is 70 A to 100 A, the substrate bias voltage is -20 V to -90 V, the duty cycle is 70% to 90%, and the deposition time is 80 min to 120 min. In some optional embodiments, during the deposition of the surface layer, the conditions of the electromagnetic permanent magnet composite magnetic field include: an electromagnetic voltage of 4.8 V to 50 V (e.g., 4.8 V, 5 V, 10 V, 20 V, 30 V, 40 V, or 50 V), an electromagnetic frequency of 1.0 Hz to 33.3 Hz (e.g., 1 Hz, 5 Hz, 10 Hz, 15 Hz, 20 Hz, 25 Hz, 30 Hz, or 33.3 Hz), and permanent magnet parameters of 5000 Gs to 15000 Gs (e.g., 5000 Gs, 8000 Gs, 10000 Gs, 12000 Gs, or 15000 Gs). Preferably, the electromagnetic voltage is 4.8V, the electromagnetic frequency is 1.0Hz, and the permanent magnet parameters are 5000Gs~15000Gs. During the deposition of the surface layer, the conditions for arc ion plating include: furnace pressure of 0.8 Pa to 2 Pa (e.g., 0.8 Pa, 1 Pa, 1.5 Pa, or 2 Pa), temperature of 250℃ to 450℃ (e.g., 250℃, 300℃, 350℃, 400℃, or 450℃), arc target current of 50A to 120A (e.g., 50A, 80A, 100A, or 120A), substrate bias of -50V to -250V (e.g., -50V, -30V, -10V, -20V, -30V, -40V, -50V, -100V, -150V, -200V, or -250V), duty cycle of 50% to 90% (e.g., 50%, 60%, 70%, 75%, 80%, 85%, or 90%), and deposition time not exceeding 300 min. Preferably, the furnace pressure is 0.8 Pa to 2 Pa, the temperature is 250 °C to 450 °C, the arc target current is 100 A to 120 A, the substrate bias voltage is -10 V to -250 V (more preferably -20 V to -70 V), the duty cycle is 70% to 90%, and the deposition time is 100 min to 160 min.

[0060] It should be noted that the deposition time is crucial in the above-mentioned preparation of the layer structure. By adjusting the deposition time, the thickness ratio of the bottom layer and the top layer of the composite coating can be different. This has an important impact on the coating's resistance to high-temperature oxidation and the interdiffusion between the coating and the substrate. By controlling the appropriate thickness, the coating can exhibit good resistance to high-temperature oxidation while having a small interdiffusion zone with the substrate.

[0061] In some alternative embodiments, the temperature of vacuum heat treatment is 800°C to 1100°C (e.g., 800°C, 850°C, 900°C, 950°C, 1000°C, 1050°C, or 1100°C), and the treatment time is 2h to 6h (e.g., 2h, 3h, 4h, 5h, or 6h).

[0062] The above-mentioned vacuum heat treatment can further improve the bonding strength between coatings and between the coating and the substrate, thereby improving the overall performance of the coating at high temperatures and extending its lifespan.

[0063] Continuing from the above, this invention employs an arc ion plating method and prepares a base layer and a top layer with a specific elemental composition under an electromagnetic permanent magnet composite magnetic field. By adjusting the thickness ratio of the base layer and the top layer, a thermal protective composite coating with effects such as resistance to high-temperature oxidation and minimal interdiffusion is prepared.

[0064] In addition, the present invention also provides an application of the above-mentioned thermal protective composite coating, for example, the thermal protective composite coating can be used to prepare hot-end components of aero engines or gas turbines.

[0065] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0066] Example 1 This embodiment provides a thermal protective composite coating, the preparation method of which includes the following steps: Step (1): Use second-generation single-crystal nickel-based alloy N5 as the substrate, polish its surface with SiC sandpaper, and then use alcohol, acetone, deionized water for ultrasonic cleaning and sandblasting to remove grease and oxide scale from the substrate surface.

[0067] Step (2): Prepare NiCrAlY and AlSiY targets for later use. The NiCrAlY target composition, by atomic percentage, is: 30% Cr, 13% Al, 0.5% Y, with the balance being Ni. The AlSiY target composition, by atomic percentage, is: 0.5% Si and 0.5% Y, with the balance being Al.

[0068] Step (3): Perform high-bias ion cleaning on the substrate under the following conditions: evacuate the vacuum to 5.0 × 10⁻⁶. -3The argon pressure is 1.0 Pa, the substrate bias voltage is -500 V, and the cleaning time is 30 min.

[0069] Step (4): Deposit the bottom layer (NiCrAlY coating, thickness 12μm) on the substrate surface after high bias ion cleaning under the following conditions: electromagnetic voltage 4.8V, electromagnetic frequency 1.0Hz, permanent magnet 10000Gs; furnace temperature 300℃, furnace pressure 1.0Pa, argon flow rate 200sccm, arc target current 70A, substrate bias voltage -70V, duty cycle 70%, deposition time 80min.

[0070] Step (5): Perform metal ion cleaning on the substrate under the following conditions: Evacuate the vacuum to 5.0 × 10⁻⁶. -3 High-pressure argon ion cleaning was performed at a pressure of 0.8 Pa, a bias voltage of -500 V applied to the substrate, and a time of 30 min. The target current was 70 A and the cleaning time was 20 min.

[0071] Step (6): Deposit a top layer (AlSiY top layer, thickness 25μm) on the bottom surface after metal ion cleaning under the following conditions: electromagnetic voltage 4.8V, electromagnetic frequency 1.0Hz, permanent magnet 5000Gs; furnace temperature 300℃, furnace pressure 0.8Pa, arc target current 120A, substrate bias voltage -50V, duty cycle 70%, deposition time 160min.

[0072] Step (7): Place the sample with the deposited surface layer into a vacuum heat treatment furnace, maintain the vacuum level, and heat treat at 900℃ for 5 hours to obtain a heat-protective composite coating.

[0073] Example 2 This embodiment provides a thermal protection composite coating (such as...) Figure 1 As shown), its preparation method includes the following steps: Step (1): Same as in Example 1.

[0074] Step (2): Prepare NiCrAlY and AlSiY targets for later use. The composition of NiCrAlY target is 28%Cr, 8%Al, 1.0%Y, with the balance being Ni. The composition of AlSiY target is 5%Si, 2%Y, with the balance being Al.

[0075] Step (3): Same as in Example 1.

[0076] Step (4): Deposit the bottom layer (NiCrAlY coating, thickness 15μm) on the substrate surface after high bias ion cleaning under the following conditions: electromagnetic voltage 4.8V, electromagnetic frequency 1.0Hz, permanent magnet 10000Gs; furnace temperature 250℃, furnace pressure 1.0Pa, argon flow rate 200sccm, arc target current 70A, substrate bias voltage -70V, duty cycle 70%, deposition time 120min.

[0077] Step (5): Same as in Example 1.

[0078] Step (6): Deposit a top layer (AlSiY top layer, thickness 16μm) on the bottom surface after metal ion cleaning under the following conditions: electromagnetic voltage 4.8V, electromagnetic frequency 1.0Hz, permanent magnet 5000Gs; furnace temperature 250℃, furnace pressure 1Pa, arc target current 120A, substrate bias voltage -50V, duty cycle 70%, deposition time 120min.

[0079] Step (7): Place the sample with the deposited surface layer into a vacuum heat treatment furnace, maintain the vacuum level, and heat treat at 900℃ for 6 hours to obtain a heat-protective composite coating.

[0080] Example 3 The difference between this embodiment and embodiment 1 is that: in step (4), the deposition time of the underlying NiCrAlY layer is 100 min; in step (5), the deposition time of the AlSiY layer is 100 min.

[0081] Example 4 The difference between this embodiment and Embodiment 1 is that the target material for preparing the bottom layer (NiCoCrAlY layer) is a NiCoCrAlY target, and the target material for preparing the top layer (AlSi layer) is an AlSi target.

[0082] The composition of the NiCoCrAlY target, by atomic percentage, is: 25% Co, 30% Cr, 10% Al, 1% Y, with the balance being Ni. The composition of the AlSi target is: 4% Si, with the balance being Al.

[0083] The cross-sectional SEM image of the obtained thermal protective composite coating is shown below. Figure 2 As shown.

[0084] Example 5 The difference between this embodiment and embodiment 1 is that in step (4), the preparation conditions of the bottom layer are as follows: the electromagnetic voltage is 4.8V, the electromagnetic frequency is 1.0Hz, the permanent magnet is 15000Gs; the furnace temperature is 400℃, the furnace pressure is 2.0Pa, the argon flow rate is 200sccm, the arc target current is 90A, the substrate bias voltage is -90V, the duty cycle is 90%, and the deposition time is 80min.

[0085] In step (6), the surface layer is prepared under the following conditions: electromagnetic voltage is 4.8V, electromagnetic frequency is 1.0Hz, permanent magnet is 15000Gs; furnace temperature is 400℃, furnace pressure is 2Pa, arc target current is 100A, substrate bias voltage is -70V, duty cycle is 90%, and deposition time is 160min.

[0086] Example 6 The difference between this embodiment and embodiment 1 is that in step (4), the preparation conditions of the bottom layer are as follows: the electromagnetic voltage is 4.8V, the electromagnetic frequency is 1.0Hz, the permanent magnet is 10000Gs; the furnace temperature is 450℃, the furnace pressure is 1.5Pa, the argon flow rate is 200sccm, the arc target current is 100A, the substrate bias voltage is -20V, the duty cycle is 90%, and the deposition time is 80min.

[0087] In step (6), the surface layer is prepared under the following conditions: electromagnetic voltage is 4.8V, electromagnetic frequency is 1.0Hz, permanent magnet is 10000Gs; furnace temperature is 450℃, furnace pressure is 1.5Pa, arc target current is 100A, substrate bias voltage is -20V, duty cycle is 90%, and deposition time is 160min.

[0088] Example 7 The difference between this embodiment and Embodiment 2 is that the target material for preparing the bottom layer (NiCrAlYHfTa layer) is a NiCrAlYHfTa target, and the target material for preparing the top layer (AlSiYZrCe layer) is an AlSiYZrCe target.

[0089] The NiCrAlYHfTa target material, by atomic percentage, consists of 28%Cr, 8%Al, 1.0%Y, 1.5%Ta, and 1.5%Hf, with the balance being Ni. The AlSiYZrCe target material consists of 5%Si, 2%Y, 2%Zr, and 2%Ce, with the balance being Al.

[0090] Example 8 The difference between this embodiment and Embodiment 2 is that the target material for preparing the bottom layer (NiCrAlYHfTaSi layer) is a NiCrAlYHfTaSi target, and the target material for preparing the top layer (AlSiYCeZr layer) is an AlSiYCeZr target.

[0091] In terms of atomic percentage, the NiCrAlYHfTaSi target material consists of 28%Cr, 8%Al, 1.0%Y, 1.5%Ta, 1.5%Hf, and 1.5%Si, with the balance being Ni; the AlSiYCeZr target material consists of 5%Si, 2%Y, 2%Ce, and 2%Zr, with the balance being Al.

[0092] Comparative Example 1 This comparative example uses the matrix from Example 1.

[0093] Comparative Example 2 The difference between this comparative example and Example 2 is that it does not contain an Al-rich surface layer. In terms of atomic percentage, the NiCrAlY target material contains 28% Cr, 8% Al, 1% Y, and the balance is Ni.

[0094] In this comparative example, the total thickness of the bottom layer is the same as the total thickness of the thermal protective composite coating in Example 2.

[0095] Comparative Example 3 The difference between this comparative example and Example 2 is that it contains only the top layer, without the bottom layer. The AlSiY target used to prepare the top layer contains 5% Si, 2.0% Y, and the balance is Al. The deposition time for the top layer is 240 min.

[0096] In this comparative example, the total thickness of the surface layer is the same as the total thickness of the thermal protective composite coating in Example 2. The cross-sectional SEM image of the obtained thermal protective composite coating is shown below. Figure 3 As shown.

[0097] Comparative Example 4 The difference between this comparative example and Example 2 is that, under the condition that the total thickness of the thermal protective composite coating is the same, the bottom layer is 3μm and the top layer is 28μm.

[0098] Comparative Example 5 The difference between this comparative example and Example 2 is that, under the condition that the total thickness of the thermal protective composite coating is the same, the bottom layer is 29 μm and the top layer is 2 μm.

[0099] Comparative Example 6 The difference between this comparative example and Example 2 is that the content of Al in the bottom layer is 5%.

[0100] The cross-sectional SEM image of the obtained thermal protective composite coating is shown below. Figure 4 As shown.

[0101] Comparative Example 7 The difference between this comparative example and Example 2 is that, in terms of atomic percentage, the NiCrAlY target material consists of 8% Al, 1.0% Y, and the balance being Ni. That is, the underlying layer does not contain Cr.

[0102] Comparative Example 8 The difference between this comparative example and Example 2 is that, in terms of atomic percentage, the NiCrAlY target material consists of 28% Cr, 8% Al, and the balance being Ni. That is, the underlying layer does not contain Y.

[0103] Comparative Example 9 The difference between this comparative example and Example 2 is that the Al content in the surface layer is 100%.

[0104] Comparative Example 10 The difference between this comparative example and Example 2 is that the deposition of the bottom and top layers was not carried out under the conditions of an electromagnetic permanent magnet composite magnetic field.

[0105] Test case The heat-treated samples from Examples 1-8 and Comparative Examples 1-10 were placed in a muffle furnace at 1150℃ for isothermal static oxidation testing for 300 hours. The results are shown in Table 1.

[0106] Table 1 Test Results

[0107] As can be seen from Table 1, the thermal protective composite coating prepared in the embodiments of the present invention has a low average oxidation rate at high temperatures and the interdiffusion phenomenon is not obvious.

[0108] By comparing Examples 1-8 with Comparative Example 1, it can be seen that preparing the bottom layer and top layer on the substrate surface can provide effective high-temperature protection for the substrate and improve its resistance to high-temperature oxidation.

[0109] By comparing Example 2 with Comparative Example 2, it can be seen that: a single NiCrAlY layer has limited thermal protection effect on the substrate at 1150℃, while the NiCrAlY / AlQ composite coating has excellent thermal protection effect.

[0110] In summary, the thermal protective composite coating provided by this invention, by depositing a bottom layer with a specific elemental composition on the substrate surface, and then depositing a top layer with a specific elemental composition on the bottom layer surface, creates an Al-rich layer on the surface of the thermal protective composite coating. This provides an Al source for the continuous generation of dense Al2O3 on the surface, thus improving its resistance to high-temperature oxidation. The bottom layer, acting as a transition layer between the top layer and the substrate, alleviates the significant compositional difference between the two, reduces interdiffusion between the coating and the substrate, and reduces the precipitation of harmful TCP phases, thereby improving the coating's lifespan and stability, and realizing the preparation of a high-performance thermal protective composite coating.

[0111] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A thermal protective composite coating, characterized in that, The thermal protection composite coating comprises a base layer and a top layer sequentially disposed from the inside to the outside on the substrate surface; The bottom layer contains elements including M, Cr, Al, and Y, where M includes at least one of Co and Ni. By atomic percentage, Cr comprises 25%–35% of the bottom layer, Al comprises 8%–15%, and Y comprises 0.5%–5%. When M contains Co, the Co content in the bottom layer does not exceed 60%. When M contains Ni, the Ni content in the bottom layer does not exceed 60%. The surface layer contains elements including Al and Q, where Q includes at least one of Si, Y, Ce, and Zr; the content of Al in the surface layer is not less than 50% and less than 100% by atomic percentage; when Q contains Si, the content of Si in the surface layer is 0.5% to 5%; when Q contains Y, the content of Y in the surface layer is 0.5% to 5%; when Q contains Ce, the content of Ce in the surface layer is 0.5% to 5%; when Q contains Zr, the content of Zr in the surface layer is 0.5% to 5%. The thickness of the bottom layer and the top layer are both independently not exceeding 40 μm, and the total thickness of the bottom layer and the top layer is not exceeding 40 μm. The thickness ratio of the bottom layer to the top layer is 0.2:1 to 1:

1. The average oxidation rate of the thermal protective composite coating after being oxidized at a constant temperature of 1150℃ for 300 hours does not exceed 0.1 g / (m²). 2 •h); The thickness of the interdiffusion zone formed by the thermal protective composite coating after constant temperature oxidation at 1150℃ for 300h does not exceed 90μm.

2. The thermal protective composite coating according to claim 1, characterized in that, The content of Cr in the bottom layer is 28%~35%, the content of Al in the bottom layer is 10%~13%, and the content of Y in the bottom layer is 1%~3%.

3. The thermal protective composite coating according to claim 2, characterized in that, The bottom layer also includes Z, which includes at least one of Ta, Hf and Si; by atomic percentage, when Z contains Ta, the content of Ta in the bottom layer is 0.5% to 5%; when Z contains Hf, the content of Hf in the bottom layer is 0.5% to 5%; when Z contains Si, the content of Si in the bottom layer does not exceed 8%.

4. The thermal protective composite coating according to claim 3, characterized in that, The Si content in the bottom layer is 3% to 5%.

5. The thermal protective composite coating according to claim 1, characterized in that, The content of Si in the surface layer is 4%~5%, and the content of Y in the surface layer is 1%~2%.

6. A method for preparing a thermally protective composite coating as described in any one of claims 1 to 5, characterized in that, Includes the following steps: The bottom layer and the top layer are sequentially prepared on the surface of the substrate.

7. The preparation method according to claim 6, characterized in that, Under the condition of an electromagnetic permanent magnet composite magnetic field, the bottom layer and the top layer are sequentially deposited on the surface of the substrate by arc ion plating, followed by vacuum heat treatment.

8. The preparation method according to claim 7, characterized in that, After the bottom layer is deposited, the bottom layer is first cleaned, and then the top layer is deposited.

9. The preparation method according to claim 7, characterized in that, The substrate is a high-temperature alloy substrate.

10. The preparation method according to claim 7, characterized in that, The matrix is ​​a Ni-based high-temperature alloy matrix.

11. The preparation method according to claim 7, characterized in that, During the deposition of the underlying layer, the conditions of the electromagnetic permanent magnet composite magnetic field include: electromagnetic voltage of 2.4V~50V, electromagnetic frequency of 1.0Hz~33.3Hz, and permanent magnet parameters of 5000Gs~15000Gs. The conditions for arc ion plating include: furnace pressure of 0.5 Pa to 3.5 Pa, temperature of 250 ℃ to 450 ℃, arc target current of 50 A to 120 A, substrate bias voltage of -50 V to -250 V, duty cycle of 70% to 90%, and deposition time not exceeding 300 min.

12. The preparation method according to claim 11, characterized in that, The electromagnetic voltage is 4.8V~50V.

13. The preparation method according to claim 11, characterized in that, The pressure inside the furnace is 0.8 Pa to 2 Pa.

14. The preparation method according to claim 7, characterized in that, During the deposition of the surface layer, the conditions of the electromagnetic permanent magnet composite magnetic field include: electromagnetic voltage of 4.8V~50V, electromagnetic frequency of 1.0Hz~33.3Hz, and permanent magnet parameters of 5000Gs~15000Gs. The conditions for arc ion plating include: furnace pressure of 0.8 Pa to 2 Pa, temperature of 250 °C to 450 °C, arc target current of 50 A to 120 A, substrate bias voltage of -50 V to -250 V, duty cycle of 50% to 90%, and deposition time not exceeding 300 min.

15. The preparation method according to claim 14, characterized in that, The substrate bias voltage is -10V to -250V.

16. The preparation method according to claim 14, characterized in that, The duty cycle is 70% to 90%.

17. The preparation method according to claim 7, characterized in that, The temperature for vacuum heat treatment is 800℃~1100℃, and the treatment time is 2h~6h.

18. The application of a thermal protective composite coating as described in any one of claims 1 to 5, characterized in that, The thermal protection composite coating is used to prepare hot-end components of aero-engines or gas turbines.

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