Preparation method of MCrAlY surface high-temperature-resistant infrared low-emissivity coating
By introducing a multilayer composite structure consisting of an α-Al2O3 layer, a dense Al2O3 layer, and a platinum oxide transition layer into the coating, the problems of stability and low emissivity of existing coatings under high-temperature environments are solved, and coatings with high adhesion and low infrared emissivity are prepared, making them suitable for high-temperature components.
Patent Information
- Application Number
- CN202511553707.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-29
- Publication Date
- 2026-02-03
AI Technical Summary
Existing methods for preparing infrared low emissivity coatings suffer from problems such as complex processes, high film stress, numerous surface defects, and insufficient anti-diffusion performance, especially in high-temperature environments where it is difficult to maintain stability and low emissivity.
An α-Al₂O₃ layer was generated using physical vapor deposition as the main diffusion barrier. A dense Al₂O₃ layer was prepared by atomic layer deposition. A platinum oxide transition layer and a Pt layer were deposited by reactive magnetron sputtering to form a multilayer composite structure, thereby optimizing the interfacial bonding strength and matching of thermal expansion coefficients.
It achieves coating stability and low emissivity performance in high-temperature environments, reduces process complexity and equipment costs, has a coating adhesion of over 20MPa, and has high surface quality that requires no subsequent polishing, making it suitable for complex surface parts.
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Figure CN121451184A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of surface treatment engineering, and particularly relates to a preparation method of an MCrAlY surface high-temperature-resistant infrared low-emissivity coating. BACKGROUND
[0002] The terminal guidance of current surface-to-air missiles mainly relies on the detection of infrared signals of the aircraft. Research shows that the infrared radiation of the aircraft engine exhaust system mainly includes high-temperature tail jet and thermal cavity radiation. Among them, the thermal cavity radiation is derived from the solid surfaces such as the center cone, flame stabilizer, turbine components and nozzle inner wall, and the radiation energy accounts for about 80% of the total engine radiation, which is the main source of 3-5 μm band infrared radiation.
[0003] In order to reduce the infrared detectability of the aircraft, applying a low-emissivity coating on the surface of high-temperature components is an effective means. The main material system of the current high-temperature-resistant infrared low-emissivity coating is metal oxide and high-temperature-stable noble metal, among which the coating system with platinum (Pt) as the surface layer is one of the preferred material systems that can realize low infrared emissivity at a high temperature above 900 ℃. The Pt layer can reduce the emissivity of the component surface to below 0.2, but it is easy to have element interdiffusion with the substrate at high temperature, resulting in the increase of infrared emissivity and performance degradation. Therefore, an element diffusion barrier mainly made of metal oxide and ceramic is usually arranged between the Pt layer and the substrate to block the mutual diffusion. At present, the preparation of the element diffusion barrier mainly has the following problems: (1) The atmospheric plasma spraying is one of the commonly used processes for preparing the oxide diffusion barrier, which has the advantages of simple process, no need for vacuum environment, low cost and high deposition efficiency. However, the coating prepared by this method has loose organization and large roughness, and the roughness is generally above Ra 2-3 μm. Since the surface roughness directly affects the infrared emissivity, the coating must be polished subsequently to control the roughness. For the parts with complex profile, the tens to hundreds of microns thick oxide coating must be uniformly polished, which is not only cumbersome and difficult, but also easy to cause microcracks in the internal, and these cracks may become the channel for element diffusion, which may weaken the protection effect of the diffusion barrier.
[0004] (2) The magnetron sputtering technology can prepare a thin film with smooth surface and dense structure, but the deposition rate is low, and it usually takes more than 10 hours to prepare a 2 μm thick oxide layer, and the process control is difficult, and the oxygen content needs to be accurately controlled in the transition zone: if the oxygen content is too high, the target material will be poisoned, which will cause the deposition rate to drop sharply; if the oxygen content is too low, the metal content in the coating will be too high, and the element blocking performance will be reduced. In addition, the intrinsic internal stress of the sputtered film is large, so that the critical thickness is usually difficult to exceed 2-3 μm. In order to realize a thicker film, multiple heat treatments and depositions are often required, which is complex and inefficient.
[0005] (3) At present, SiO2 is an ideal diffusion barrier material, which has very low diffusion coefficient for elements such as Ni and Pt at high temperature. However, there is a problem of mismatch of expansion coefficients between SiO2 and the metal matrix and the Pt layer. In order to improve the interface bonding and reduce thermal stress, other oxides such as ZnO and TiO2 are usually introduced for adjustment, but this method often leads to a decrease in the intrinsic diffusion barrier performance while enhancing the bonding strength.
[0006] In summary, the existing preparation methods of element diffusion barrier of infrared low-emissivity coating generally have problems such as complex process, high film stress, many surface defects and insufficient diffusion prevention performance, which are not conducive to industrial application. SUMMARY
[0007] In view of the above problems, the present application provides a preparation method of MCrAlY surface high-temperature-resistant infrared low-emissivity coating, and the prepared MCrAlY surface high-temperature-resistant infrared low-emissivity coating has a multilayer composite structure of "thermal oxidation α-Al2O3 main diffusion barrier \ ALD dense Al2O3 nano-pore sealing layer \ platinum oxide transition layer \ Pt layer", which endows the coating with excellent element barrier performance and interface bonding strength.
[0008] In a first aspect, the present application provides a preparation method of high-temperature-resistant infrared low-emissivity coating, comprising the following steps: S1. depositing an Al layer on the surface of a substrate with a MCrAlY bonding layer by physical vapor deposition, and then performing thermal oxidation treatment to form an α-Al2O3 layer; S2. depositing a dense Al2O3 layer on the surface of the α-Al2O3 layer by atomic layer deposition; S3. depositing a platinum oxide transition layer on the surface of the dense Al2O3 layer by reactive magnetron sputtering, and then depositing a Pt layer on the surface of the platinum oxide transition layer by magnetron sputtering; S4. performing heat treatment on the substrate after step S3 to complete the preparation of the high-temperature-resistant infrared low-emissivity coating.
[0009] The application generates an alpha-Al2O3 main diffusion barrier by physical vapor deposition of an Al layer followed by thermal oxidation. The high oxygen affinity of Al at high temperatures allows selective oxidation of Al over other elements in the substrate, thereby generating a pure and continuous alpha-Al2O3 layer on the substrate. At the initial stage of thermal oxidation, interdiffusion occurs between the deposited Al layer and the Al element in the MCrAlY bonding layer, forming a compositionally graded transition zone, which not only effectively relieves the interface stress concentration, but also significantly improves the interface strength through metallurgical bonding. In addition, since the thermal expansion coefficients of alpha-Al2O3, MCrAlY and Pt match well, and the element diffusion coefficient of alpha-Al2O3 is extremely low, it becomes an ideal diffusion barrier material, ensuring the stability and durability of the coating system in high temperature environment. This process does not require a complex vacuum reaction sputtering environment and precise control of oxygen content, and also avoids the use of large size vacuum cavities, with a wide process window, simple operation and good repeatability.
[0010] To further improve the diffusion barrier performance, a dense Al2O3 layer is prepared as a top diffusion barrier on the surface of the alpha-Al2O3 layer by atomic layer deposition (ALD). The dense Al2O3 layer can be grown layer by layer with single atomic layer precision based on the uniform adsorption and reaction of precursor gas molecules on the surface, effectively covering and plugging the micro defects on the surface of the bottom layer, and finally forming a dense Al2O3 barrier layer with complete structure and almost no defects, greatly improving the long-term stability and reliability of the coating system at high temperature.
[0011] In terms of low-emissivity surface layer design, the application first deposits a platinum oxide transition layer on the surface of the dense Al2O3 diffusion barrier using reactive magnetron sputtering. The transition layer establishes a stable chemical gradient interface between the ceramic Al2O3 layer and the metal Pt layer through chemical bonding, significantly enhancing the interfacial adhesion and effectively relieving the interfacial stress concentration caused by the difference in thermal expansion coefficients. Then, a high-purity Pt layer is deposited as a functional surface layer using magnetron sputtering technology, fully utilizing the intrinsic low infrared emissivity of Pt material. This composite structure of gradient transition and functional surface layer not only ensures the interface stability of the coating system in high temperature environment, but also enables the coating to maintain an emissivity of less than 0.25 for a long period of time.
[0012] Preferably, in step S1, the substrate with MCrAlY bonding layer is selected from nickel-based superalloys with a surface roughness Ra<0.5 μm. The nickel-based superalloys include, but are not limited to, K465, DZ411, DD6, IN718, IN738 or GH4169, and other suitable types for high temperature components.
[0013] It should be noted that the high-temperature-resistant infrared low-emissivity coating system provided by the present application has wide application adaptability. It can be prepared on the substrate with an MCrAlY bonding layer on the surface, and the excellent oxidation resistance and bonding performance provided by the MCrAlY layer can be utilized; or it can be directly applied to the surface of an alloy such as a nickel-based high-temperature alloy after appropriate surface treatment (such as achieving a surface roughness requirement of Ra<0.5 μm and a cleanliness requirement). When directly applied to the surface of the alloy, the deposited Al layer and the interdiffusion and metallurgical bonding formed with the surface of the alloy substrate at the initial stage of thermal oxidation can also construct an interface with strong bonding force and good thermal matching, and then through the deposition of a subsequent dense Al2O3 layer, a platinum oxide transition layer and a platinum layer, a high-performance infrared low-emissivity coating is finally formed.
[0014] It should be noted that the present application does not make specific limitations on the method for preparing the MCrAlY bonding layer on the surface of the substrate, such as thermal spraying or cold spraying technology. The present application also does not make specific limitations on the material and thickness of the MCrAlY bonding layer prepared on the surface of the substrate, for example, the M in the MCrAlY bonding layer can be Co element or Ni element, and is preferably NiCrAlY bonding layer or NiCoCrAlY bonding layer. In addition, the thickness of the MCrAlY bonding layer can be 0.1-0.5 mm, for example, 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, etc. At the same time, in order to ensure the low infrared emissivity performance of the coating, the surface roughness of the substrate with the MCrAlY bonding layer needs to be controlled to be less than 0.5 μm through wet sand blasting and the like.
[0015] Further preferably, in order to ensure the surface cleanliness and activity, the surface of the substrate with the MCrAlY bonding layer is cleaned before the coating is prepared, and the cleaning methods include but are not limited to solvent cleaning, plasma cleaning, sand blasting treatment and the like.
[0016] Preferably, in step S1, the thickness of the Al layer is 2 μm-4 μm.
[0017] The thickness of the physical vapor deposition aluminum layer is preferably 2 μm-4 μm, which ensures that there is sufficient aluminum source to generate a continuous, dense and appropriately thick main diffusion barrier of α-Al2O3 layer through thermal oxidation. If the thickness is insufficient, the oxidation layer is easy to be discontinuous and cannot effectively block element interdiffusion; if the thickness is too thick, the oxidation growth stress and thermal mismatch stress will significantly increase, increasing the risk of interface peeling. At the same time, the Al layer with this thickness can form a compositionally gradient interdiffusion zone with the MCrAlY bonding layer at the initial stage of thermal oxidation, which not only significantly enhances the interface bonding force through metallurgical bonding, but also avoids the problem of dramatic increase of internal stress caused by the thick aluminum layer.
[0018] Preferably, in step S1, the holding time of the thermal oxidation treatment is 2-3 hours, and the temperature is 900-1050℃.
[0019] Preferably, in step S2, the thickness of the dense Al2O3 layer is 100-300 nm.
[0020] Preferably, the thickness of the dense Al2O3 layer prepared by the atomic layer deposition (ALD) method is 100-300 nm. This thickness range can completely cover the micro defects of the underlying alpha-Al2O3 thermal oxidation layer by utilizing the layer-by-layer growth characteristics of the ALD technology, forming a nanoporous sealing barrier, which can ensure the diffusion barrier performance while avoiding the incomplete coverage problem that may occur when the thickness is less than 100 nm, and the process efficiency reduction and film internal stress accumulation risk caused by the excessive deposition time when the thickness exceeds 300 nm.
[0021] Preferably, in step S2, the process parameters of the atomic layer deposition method include: the deposition temperature is 100-200℃, the precursor is trimethylaluminum, the reactant is water vapor, the carrier gas and the purge gas are nitrogen, and the working pressure is 100-1000 Pa.
[0022] Preferably, the process of each deposition growth cycle of the atomic layer deposition method is as follows: trimethylaluminum precursor is carried into the deposition cavity by nitrogen carrier gas, the pulse time is 0.1-0.5 s; nitrogen is used to purge the deposition cavity and the pipeline, the purging time is 3-5 s; water vapor reactant is carried into the deposition cavity by nitrogen carrier gas, the pulse time is 0.1-0.5 s; nitrogen is used to purge the deposition cavity and the pipeline, the purging time is 3-5 s.
[0023] Preferably, in step S3, the process parameters of the reactive magnetron sputtering method include: the target material is Pt, the direct current magnetron sputtering power is 80-120 W, the argon flow rate is 140-160 sccm, the oxygen flow rate is 8-12 sccm, the vacuum chamber pressure is 0.5-1.5 Pa, and the deposition time is 4-6 min.
[0024] Preferably, in step S3, the thickness of the platinum oxide transition layer is 10-50 nm, and the thickness of the Pt layer is 2-3 μm.
[0025] Preferably, in step S4, the heat treatment includes: heating to 900-1000℃ at a rate of 5-10℃ / min in an environment with a pressure lower than 1×10 -2 Pa, and holding for 1-3 hours.
[0026] The preferred heat treatment process of the present application effectively eliminates the lattice defects and internal stress formed in the coating preparation process, promotes the interdiffusion and atomic order rearrangement of the interface elements of each layer; at the same time, through the slow heating process and the protection of the vacuum environment, the accumulation of thermal stress and the risk of high temperature oxidation are effectively prevented. This comprehensive treatment finally makes the coating interface bonding force increase to more than 20 MPa, and ensures that the Pt layer maintains stable crystal structure and low emissivity performance under long-term high temperature service conditions.
[0027] In a second aspect, the present application also provides a high-temperature-resistant infrared low-emissivity coating prepared by the above-mentioned method, which comprises from the surface of the substrate outwardly: an MCrAlY bonding layer, an alpha-Al2O3 layer, a dense Al2O3 layer, a platinum oxide transition layer, and a Pt layer.
[0028] The high-temperature-resistant infrared low-emissivity coating provided by the present application adopts a multilayer composite structure, the MCrAlY bonding layer ensures good thermal expansion matching and oxidation resistance with the substrate; the alpha-Al2O3 layer provides element blocking function as the main diffusion barrier; the dense Al2O3 layer prepared by atomic layer deposition further realizes nanoscale plugging and forms an interface structure without defects; the platinum oxide transition layer effectively relieves the thermal stress between the ceramic layer and the metal layer; and the Pt layer on the outermost layer fully plays its intrinsic low-emissivity characteristics, finally making the coating maintain an emissivity of less than 0.25 while realizing an interface bonding strength of more than 20 MPa, and having excellent thermal stability and service reliability.
[0029] The preparation method of the MCrAlY surface high-temperature-resistant infrared low-emissivity coating provided by the present application has the following beneficial effects compared with the prior art: (1) The present application proposes a simple and controllable element diffusion barrier preparation method, which first generates an alpha-Al2O3 layer through a thermal oxidation process, utilizes the matching of the thermal expansion coefficients of the metal bottom layer and the Pt layer, effectively reduces the thermal stress of the coating at high temperature; on this basis, by introducing platinum oxide as a transition layer before depositing the Pt layer, the interlayer thermal expansion coefficient matching is further optimized, and finally an infrared low-emissivity coating with high bonding force is prepared. The preparation method provided by the present application is simple and easy to operate, has good repeatability, avoids the requirement for precise control of oxygen partial pressure in traditional reactive magnetron sputtering, reduces the process complexity and equipment cost, and the prepared coating is dense, has high surface quality and almost no defects, and does not need subsequent polishing treatment, which is especially suitable for high-temperature components with complex surfaces, greatly reduces the equipment investment and production cost.
[0030] (2) The MCrAlY surface high-temperature-resistant infrared low-emissivity coating provided by the application has a multilayer composite structure of "thermal oxidation α-Al2O3 main diffusion barrier\ALD dense Al2O3 nano sealing layer\platinum oxide transition layer\pt layer", wherein the thermal oxidation layer provides the main barrier thickness, the ALD layer realizes the sealing of surface defects, and the platinum oxide layer effectively relieves the thermal mismatch stress between the ceramic layer and the metal layer. The gradient transition design makes the coating have excellent element barrier performance and interface bonding strength, and the bonding strength of the coating is higher than 20 MPa. BRIEF DESCRIPTION OF DRAWINGS
[0031] Figure 1 is an X-ray diffraction (XRD) spectrum of the α-Al2O3 layer in Example 1 of the application; Figure 2 is an energy spectrum line scanning diagram of the α-Al2O3 layer in Example 1 of the application; Figure 3 is a schematic diagram of a traditional infrared low-emissivity coating structure; Figure 4 is a schematic diagram of the high-temperature-resistant infrared low-emissivity coating structure in Example 1 of the application. DETAILED DESCRIPTION
[0032] In order to more clearly illustrate the specific embodiments of the application or the technical solutions in the prior art, the specific embodiments will be briefly introduced below, and obviously, the embodiments described below are some embodiments of the application, and other embodiments can also be obtained by those skilled in the art without creative labor on the basis of these embodiments.
[0033] If the specific experimental steps or conditions are not specified in the embodiments, the operations or conditions can be performed according to the conventional experimental steps described in the literature in the art. The raw materials or instruments used are conventional products that can be obtained by purchase, including but not limited to the raw materials or instruments used in the embodiments of the application.
[0034] Example 1 The embodiment provides a preparation method of an MCrAlY surface high-temperature-resistant infrared low-emissivity coating, comprising the following steps: (1) A K465 high-temperature alloy low-pressure turbine blade with a NiCrAlY bonding layer on the surface is selected as a substrate, the bonding layer has been subjected to thermal diffusion treatment with the alloy substrate, and the surface roughness is controlled to be 0.48 μm through wet sand blasting; the substrate is ultrasonically cleaned with acetone, anhydrous ethanol and deionized water for 20 min, and then dried for standby use; after the cleaned substrate is placed in a vacuum chamber, the vacuum degree is extracted to 1×10 -3 Pa, argon is introduced and plasma cleaning etching is performed for 30 min to remove surface contaminants and improve surface activity; The temperature of the vacuum chamber was raised to 150°C and kept for 30 min; then a layer of Al was deposited on the surface of the substrate NiCrAlY bonding layer by using a direct current magnetron sputtering process, the direct current magnetron sputtering power was 200 W, the target material was Al with a purity of 99.9%, the argon flow rate was 160 sccm, the vacuum chamber pressure was 1 Pa, the part self-rotation speed was 5 rpm, the coating was deposited for 30 min, and the thickness of the Al layer was about 3 μm; The substrate after the Al layer was deposited was placed in a muffle furnace, heated to 1050°C in an air atmosphere for 2 h, and then cooled in the furnace to completely convert the Al layer into an α-Al2O3 layer with a thickness of about 3.5 μm; the surface phase of the sample after oxidation in the furnace was analyzed by X-ray diffraction, and the XRD results are shown in Figure 1 , which shows that the conversion product is aluminum oxide α-Al2O3; the cross section of the aluminum oxide α-Al2O3 was observed by scanning electron microscopy and energy spectrum analysis, and the energy spectrum line scanning results are shown in Figure 2 , which shows that the thickness of the α-Al2O3 layer is about 3.5 μm, and the interface is clear and the structure is dense; (2) After the substrate obtained in step (1) was cooled and taken out, it was placed in an atomic layer deposition device, the background vacuum was pumped to 1×10 -2 Pa, argon was introduced, and the surface of the substrate was cleaned and etched for 20 min by using an ion source; Then atomic layer deposition was carried out at a process temperature of 150°C, the precursor was trimethylaluminum (TMA), the reactant was water vapor (H2O), the carrier gas and the purge gas were nitrogen (N2), and the working pressure was maintained at 1000 Pa. Each deposition and growth cycle included the following steps: 1) trimethylaluminum precursor was carried into the deposition cavity by nitrogen carrier gas, and the pulse time was 0.3 s; 2) nitrogen was used to purge the deposition cavity and the pipeline, and the purging time was 4 s; 3) water vapor reactant was carried into the deposition cavity by nitrogen carrier gas, and the pulse time was 0.3 s; 4) nitrogen was used to purge the deposition cavity and the pipeline, and the purging time was 4 s; the time of a single deposition and growth cycle was about 8 seconds, and about 0.1 nm thickness of Al2O3 was deposited per cycle. After 2000 cycles, a dense Al2O3 layer diffusion barrier with a thickness of about 200 nm was prepared; (3) The substrate obtained in step (2) was placed in a vacuum chamber, the background vacuum was pumped to 1×10 -3 Pa, argon was introduced, and plasma cleaning and etching were carried out for 30 min; Then the temperature of the vacuum chamber was raised to 200℃ and maintained for 30 min. The temperature of the vacuum chamber was raised to 200℃; a platinum oxide transition layer was deposited on the surface of the dense Al2O3 layer by a direct current reaction magnetron sputtering process, with the process parameters being: a power of 100 W, a target material being 99.99% pure Pt, an argon flow rate being 150 sccm, an oxygen flow rate being 10 sccm, a vacuum chamber pressure being 1 Pa, a part rotation speed being 5 rpm, and a deposition time being 5 min; Then the oxygen supply was stopped, other parameters were maintained, a metal Pt layer was continuously deposited for 30 min, and a Pt layer with a thickness of about 2 μm was obtained. (4) The substrate obtained in step (3) was placed in a vacuum annealing furnace, and the temperature was raised to 950℃ at a rate of 10℃ / min under a pressure of 1×10 -3 Pa, and the temperature was maintained for 2 h, and then the furnace was cooled, to complete the preparation of the high-temperature-resistant infrared low-emissivity coating.
[0035] The high-temperature-resistant infrared low-emissivity coating prepared by the above method comprises, from the surface of the substrate outward, an MCrAlY bonding layer, an α-Al2O3 layer (i.e. thermal oxidation-Al2O3), a dense Al2O3 layer (i.e. ALD-Al2O3), a platinum oxide transition layer (i.e. reaction PVD-Pt oxide), and a Pt layer (i.e. PVD-Pt). The MCrAlY bonding layer is a NiCrAlY bonding layer (Ni: 69.7%, Cr: 20%, Al: 10%, Y: 0.3%), the substrate is K465 high-temperature alloy, the thickness of the MCrAlY bonding layer is 45 μm, the thickness of the α-Al2O3 layer is 3.5 μm, the thickness of the dense Al2O3 layer is 200 nm, the thickness of the platinum oxide transition layer is 30 nm, and the thickness of the Pt layer is 2 μm. A traditional infrared low-emissivity coating structure is shown in Figure 3 The high-temperature-resistant infrared low-emissivity coating structure provided in the embodiment is shown in Figure 4 .
[0036] Embodiment 2 The embodiment provides a preparation method of an MCrAlY surface high-temperature-resistant infrared low-emissivity coating, comprising the following steps: (1) A K465 high-temperature alloy baffle with a surface NiCoCrAlY bonding layer was selected as a substrate, the bonding layer had completed thermal diffusion treatment with the alloy substrate, and the surface roughness was controlled to be 0.3 μm through wet sand blasting and polishing; the substrate was ultrasonically cleaned with anhydrous ethanol and deionized water for 20 min, and then was dried for standby use after cleaning; after the cleaned substrate was placed in a vacuum chamber, argon was introduced and plasma cleaning etching was performed for 20 min after the vacuum degree was extracted to 1×10 -3 Pa. The temperature of the vacuum chamber was raised to 150℃ and maintained for 30 min; then a DC magnetron sputtering process was used to deposit an Al layer on the surface of the substrate NiCoCrAlY bonding layer, the DC magnetron sputtering power was 200 W, the target material was 99.9% pure Al, the argon flow rate was 160 sccm, the part did not rotate by itself, the rotation speed was 5 rpm, the deposition coating time was 20 min, and the thickness of the Al layer was about 2 μm; The substrate after the Al layer was deposited was placed in a muffle furnace, heated to 1000℃ in an air atmosphere for 2 h, and then cooled in the furnace to completely convert the Al layer into an α-Al2O3 layer with a thickness of about 2.2 μm; (2) The substrate obtained in step (1) was cooled and taken out and placed in an atomic layer deposition device, the background vacuum was pumped to 1×10 -2 Pa; Then atomic layer deposition was carried out at a process temperature of 150℃, the precursor was trimethylaluminum (TMA), the reactant was water vapor (H2O), the carrier gas and the purge gas were nitrogen (N2), and the working gas pressure was maintained at 200 Pa. Each deposition and growth cycle included the following steps: 1) trimethylaluminum precursor was carried by nitrogen carrier gas and introduced into the deposition cavity, the pulse time was 0.5 s; 2) nitrogen was used to purge the deposition cavity and the pipeline, the purging time was 5 s; 3) water vapor reactant was carried by nitrogen carrier gas and introduced into the deposition cavity, the pulse time was 0.5 s; 4) nitrogen was used to purge the deposition cavity and the pipeline, the purging time was 5 s; a single deposition and growth cycle took about 10 seconds, and about 0.1 nm thickness of Al2O3 was deposited per cycle. After 3000 cycles, a dense Al2O3 layer diffusion barrier with a thickness of about 300 nm was prepared; (3) The substrate obtained in step (2) was placed in a vacuum chamber, the background vacuum was pumped to 1×10 -3 Pa, argon was introduced and plasma cleaning etching was carried out for 30 min; Then the temperature of the vacuum chamber was raised to 200℃ and maintained for 30 min. The temperature of the vacuum chamber was raised to 200℃; a platinum oxide transition layer was deposited by a DC reactive magnetron sputtering process, the process parameters were: the power was 80 W, the target material was 99.99% pure Pt, the argon flow rate was 150 sccm, the oxygen flow rate was 10 sccm, the vacuum chamber pressure was 1 Pa, the rotation speed of the part was 5 rpm, and the deposition time was 4 min; Then the oxygen supply was stopped, the other parameters were maintained unchanged, and the metal Pt layer was continued to be deposited for 30 min to obtain a Pt layer with a thickness of about 2 μm; (4) The substrate obtained in step (3) was placed in a vacuum annealing furnace, the pressure was 1×10 -3 Pa, the temperature was raised to 900℃ at a rate of 10℃ / min, and the temperature was maintained for 3 h before the furnace was cooled, thereby completing the preparation of the high-temperature-resistant infrared low-emissivity coating.
[0037] The embodiment provides a high-temperature-resistant infrared low-emissivity coating prepared by the above method, which comprises, from the surface of a substrate outward, an MCrAlY bonding layer, an alpha-Al2O3 layer (i.e. thermal oxidation-Al2O3), a dense Al2O3 layer (i.e. ALD-Al2O3), a platinum oxide transition layer (i.e. reaction PVD-Pt oxide), and a Pt layer (i.e. PVD-Pt); The MCrAlY bonding layer is a NiCoCrAlY bonding layer (Cr 27.2, Co 19.1, Al 11.0, Y 0.5, and Ni balance), the substrate is K465 high-temperature alloy, the thickness of the MCrAlY bonding layer is 30 μm, the thickness of the alpha-Al2O3 layer is 2.2 μm, the thickness of the dense Al2O3 layer is 300 nm, the thickness of the platinum oxide transition layer is 15 nm, and the thickness of the Pt layer is 2 μm.
[0038] Performance test The high-temperature-resistant infrared low-emissivity coatings prepared in Embodiment 1 and Embodiment 2 are subjected to comprehensive performance tests, and the test methods are as follows: (1) Bonding strength test: the adhesion of the coating is measured by using a material tensile testing machine according to HB 5476 “Test method for bonding strength of thermal spraying coating”, and the bonding strength of the coating of Embodiment 1 is greater than 33 MPa, and the bonding strength of the coating of Embodiment 2 is greater than 35 MPa; (2) High-temperature infrared emissivity test: the infrared emissivity of the coating at 950°C is determined by using a high-temperature infrared spectrum test device according to HB 20540 “Test method for infrared emissivity of stealth materials”. The results show that, in the 3-5 μm wave band, the infrared emissivity of the coating of Embodiment 1 is 0.15, and the infrared emissivity of the coating of Embodiment 2 is 0.17; in the 8-14 μm wave band, the infrared emissivity of the coating of Embodiment 1 is 0.1, and the infrared emissivity of the coating of Embodiment 2 is 0.12; (3) Long-term thermal stability test: after the coating sample is heat-treated at 1000°C for 300 h in an air atmosphere, the normal-temperature emissivity of the sample is measured by using a handheld infrared emissivity tester. In the 3-5 μm wave band, the infrared emissivity of the coating of Embodiment 1 is 0.074, and the infrared emissivity of the coating of Embodiment 2 is 0.079; in the 8-14 μm wave band, the infrared emissivity of the coating of Embodiment 1 is 0.14, and the infrared emissivity of the coating of Embodiment 2 is 0.16, proving that the coating still has excellent low-emissivity characteristics after long-term high-temperature exposure; (4) Thermal shock resistance test: the sample after long-term heat treatment is subjected to 200 times of thermal shock cycle test from 950°C to room temperature by air cooling, and the infrared emissivity of the sample at room temperature is measured by using an infrared emissivity hand-held infrared emissivity tester. In the 3-5 μm wave band, the infrared emissivity of the coating of Example 1 is 0.082, and the infrared emissivity of the coating of Example 2 is 0.087. In the 8-14 μm wave band, the infrared emissivity of the coating of Example 1 is 0.167, and the infrared emissivity of the coating of Example 2 is 0.176, and there is no peeling phenomenon, indicating that the coating has excellent thermal cycle stability and service reliability.
[0039] Obviously, the above examples are only examples for clearly illustrating but not limiting the embodiments. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. Here, all the embodiments cannot be exhausted, and the obvious changes or variations derived therefrom are still within the protection scope of the present application.
Claims
1. A method for producing a high temperature resistant infrared low emissivity coating, characterized by, The method comprises the following steps: S1. Depositing an Al layer on the surface of a substrate with an MCrAlY bonding layer by physical vapor deposition, and then performing a thermal oxidation treatment to form an α-Al2O3 layer; S2. Depositing a dense Al2O3 layer on the surface of the α-Al2O3 layer by atomic layer deposition; S3. Depositing a platinum oxide transition layer on the surface of the dense Al2O3 layer by reactive magnetron sputtering, and then depositing a Pt layer on the surface of the platinum oxide transition layer by magnetron sputtering; S4. Performing a heat treatment on the substrate after step S3 to complete the preparation of a high-temperature-resistant infrared low-emissivity coating.
2. The method of claim 1, wherein the high temperature resistant infrared low emissivity coating is prepared by the steps of: In step S1, the substrate with an MCrAlY bonding layer is selected from a nickel-based high-temperature alloy, and the surface roughness Ra is less than 0.5 μm.
3. The method of claim 1, wherein the high temperature resistant infrared low emissivity coating is prepared by the steps of: In step S1, the thickness of the Al layer is 2 μm to 4 μm.
4. The method of claim 1, wherein the high temperature resistant infrared low emissivity coating is prepared by the steps of: In step S1, the holding time of the thermal oxidation treatment is 2 h to 3 h, and the temperature is 900 ℃ to 1050 ℃.
5. The method of claim 1, wherein the high temperature resistant infrared low emissivity coating is prepared by the steps of: In step S2, the thickness of the dense Al2O3 layer is 100 nm to 300 nm.
6. The method of claim 1, wherein the high temperature resistant, infrared low emissivity coating is prepared by the steps of: In step S2, the process parameters of the atomic layer deposition method include: a deposition temperature of 100 ℃ to 200 ℃, a trimethylaluminum precursor, water vapor as a reactant, nitrogen as a carrier gas and a purge gas, and a working pressure of 100 Pa to 1000 Pa. In each deposition and growth cycle of the atomic layer deposition method, the trimethylaluminum precursor is carried by the nitrogen carrier gas and introduced into the deposition cavity for a pulse time of 0.1 s to 0.5 s; the deposition cavity and the pipeline are purged with nitrogen for a purging time of 3 s to 5 s; the water vapor reactant is carried by the nitrogen carrier gas and introduced into the deposition cavity for a pulse time of 0.1 s to 0.5 s; and the deposition cavity and the pipeline are purged with nitrogen for a purging time of 3 s to 5 s.
7. The method of claim 1, wherein the high temperature resistant infrared low emissivity coating is prepared by the steps of: In step S3, the process parameters of the reactive magnetron sputtering method include: a Pt target, a direct-current magnetron sputtering power of 80 W to 120 W, an argon gas flow rate of 140 sccm to 160 sccm, an oxygen gas flow rate of 8 sccm to 12 sccm, a vacuum chamber pressure of 0.5 Pa to 1.5 Pa, and a deposition time of 4 min to 6 min.
8. The method for preparing a high-temperature resistant infrared low-emissivity coating as described in claim 1, characterized in that, In step S3, the thickness of the platinum oxide transition layer is 10 nm to 50 nm, and the thickness of the Pt layer is 2 μm to 3 μm.
9. The method of claim 1, wherein the high temperature resistant, infrared low emissivity coating is prepared by the steps of: In step S4, the heat treatment comprises: heating to 900℃~1000℃ at a rate of 5℃ / min~10℃ / min under an environment with a pressure lower than 1×10 -2 Pa, and holding for 1h~3h.
10. A high temperature resistant, infrared low emissivity coating prepared by the method of any one of claims 1-9, characterized in that, From the surface of the substrate outward, the layers include, in sequence: an MCrAlY bonding layer, an α-Al2O3 layer, a dense Al2O3 layer, a platinum oxide transition layer, and a Pt layer.