Multilayer composite high-temperature solar selective absorption coating and preparation method thereof

Abstract

The application discloses a multilayer composite high-temperature-resistant solar selective absorption coating and a preparation method thereof, and belongs to the technical field of solar thermal power generation. The coating comprises, from bottom to top, a NiCrAlY bonding transition layer, an Al-SiO2 infrared reflection layer, a Ni / Ti double-doped CuCoMnOx spinel composite absorption layer and a SiO2-Al2O3 composite anti-reflection layer. In the preparation, the NiCrAlY layer is deposited on the substrate by atmospheric plasma spraying and vacuum annealing, the infrared reflection layer is prepared by the dip-coating method, the Ni / Ti gradient-doped absorption layer is prepared by the radio frequency magnetron sputtering double-target co-deposition, the anti-reflection layer is formed by the sequential dip-coating, and the three-stage heat treatment is carried out. The application relieves the thermal expansion mismatch between the ceramic and the metal through the bonding layer, cooperatively regulates the spinel energy band structure through the Ni / Ti double doping, and significantly improves the spectral selectivity and the high-temperature stability.

Description

Technical Field

[0001] This invention relates to the field of solar thermal power generation technology, specifically to a multilayer composite high-temperature resistant selective solar energy absorption coating and its preparation method. Background Technology

[0002] Solar thermal power generation technology is striving to increase operating temperatures to 800℃ to overcome efficiency bottlenecks. However, high temperatures cause existing heat-absorbing coatings to easily peel off and their optical performance to degrade. Transition metal oxide spinel, due to its unique electronic band structure, exhibits intrinsic absorption characteristics in the 0.3–2.5 μm solar spectrum and remains stable at high temperatures, making it a research hotspot in the field of selective solar absorption coatings. Although spinel materials possess excellent high-temperature optical properties and stability, making them suitable as absorption layers, the significant difference in thermal expansion coefficients between the spinel phase and the metal matrix easily leads to coating cracking.

[0003] Currently, this type of coating faces severe challenges in practical applications. On the one hand, traditional single-layer or simple multi-layer structures are unable to withstand phase transformation and oxidation under high-temperature environments, resulting in a significant decline in heat absorption capacity. On the other hand, the difference in physical properties between the spinel layer and the metal substrate leads to weak interfacial bonding, resulting in frequent peeling and flaking of the coating. Summary of the Invention

[0004] The purpose of this invention is to provide a multilayer composite high-temperature resistant solar selective absorption coating and its preparation method. Through multilayer structure design and dual-element co-doping synergistic optimization, the problem of easy peeling off at high temperatures and easy degradation of optical performance of existing coatings is solved.

[0005] Therefore, in a first aspect, the present invention provides a multilayer composite high-temperature resistant solar selective absorption coating, comprising, in sequence: a bonding transition layer prepared on a metal substrate, an infrared reflective layer, a composite absorption layer, and an antireflective layer; wherein, The bonding transition layer is a NiCrAlY alloy layer; The infrared reflective layer is an Al-SiO2 composite layer; The composite absorber layer is a Ni / Ti dual-doped CuCoMnOx spinel layer; The antireflective layer is a SiO2-Al2O3 composite layer.

[0006] Furthermore, the chemical composition of the NiCrAlY alloy, by mass percentage, is: Cr 20%~25%, Al 5%~10%, Y 0.5%~1.0%, with the remainder being Ni.

[0007] Furthermore, in the infrared reflective layer, the mass ratio of SiO2 sol to Al powder is 1:(2~3).

[0008] Furthermore, in the composite absorber layer, the Ni doping amount is 3% to 7% of the total mass of the CuCoMnOx spinel matrix metal cations, and the Ti doping amount is 5% to 10% of the total mass of the metal cations.

[0009] Furthermore, the antireflection layer is composed of an inner SiO2 layer and an outer Al2O3 layer, wherein the thickness of the SiO2 layer is 80nm~120nm and the thickness of the Al2O3 layer is 60nm~100nm.

[0010] A second aspect of the present invention provides a method for preparing the above-mentioned multilayer composite high-temperature solar selective absorption coating, comprising the following steps: Step 1: Pre-treat the metal substrate; Step 2: Deposit a NiCrAlY alloy layer on the metal substrate as a bonding transition layer, and then perform vacuum diffusion annealing. Step 3: Prepare SiO2 sol, mix it with Al powder, and then use the dip-coating method to prepare an infrared reflective layer on the bonding transition layer; Step 4: Prepare Ni / Ti dual-doped CuCoMnOx spinel ceramic target, and deposit a composite absorption layer on the infrared reflective layer using radio frequency magnetron sputtering technology; Step 5: Prepare SiO2 sol and Al2O3 sol respectively, and then use the dip-coating method to prepare the inner SiO2 layer and the outer Al2O3 layer on the composite absorption layer to form an anti-reflection layer. Step 6: Heat treat the resulting coating.

[0011] Furthermore, in step 2, the process parameters for depositing the NiCrAlY coating using atmospheric plasma spraying technology are as follows: spraying distance 100mm~110mm, voltage 70V~80V, current 500A~600A, hydrogen flow rate 35L / min~50L / min, argon flow rate 6L / min~9L / min, powder feed rate 15rad / min~20rad / min, coating thickness controlled at 50μm~55μm; vacuum diffusion annealing temperature 600℃~700℃, holding time 1h~2h.

[0012] Further, in step 4, the preparation method of the Ni / Ti dual-doped CuCoMnOx spinel ceramic target includes: CuO, Co2O3, and MnO2 powders were mixed in a molar ratio of Cu:Co:Mn = 3:1:3. NiO powder and TiO2 powder were added, and the mixture was ball-milled for 5 to 7 hours. After granulation and sieving, the mixture was cold isostatically pressed under a pressure of 15 MPa to 25 MPa. The mixture was then held at 500℃ to 600℃ for 2 to 4 hours, and then sintered at 1000℃ to 1200℃ for 2 to 3 hours.

[0013] Furthermore, in step 4, the process parameters for depositing the composite absorber layer using radio frequency magnetron sputtering technology are as follows: substrate heating to 500℃~600℃, vacuum degree 2×10⁻⁶. -4 Pa~5×10 -4 Pa, Ar and O2 are introduced, working pressure is 4Pa~6Pa, ceramic target power is 700W~800W, pure Ni target power increases linearly from 80W~100W to 130W~150W, pure Ti target power increases linearly from 100W~120W to 150W~170W, sample holder rotation speed is 5r / min~10r / min, sputtering time is 60~90min.

[0014] Further, in step 6, the heat treatment method includes: First stage: Increase the temperature to 250℃~350℃ at a rate of 5℃ / min~8℃ / min, and hold for 15min~30min; Second stage: Increase the temperature to 500℃~600℃ at a rate of 4℃ / min~6℃ / min, and hold for 20min~40min; The third stage: the temperature is increased to 750℃~800℃ at a rate of 3℃ / min~5℃ / min, held for 24h~48h, and then cooled to room temperature with the furnace.

[0015] The multilayer composite high-temperature resistant solar selective absorption coating and its preparation method provided by this invention have at least the following advantages compared to the prior art: (1) The present invention introduces a NiCrAlY bonding transition layer between the metal substrate and the ceramic absorption layer. By utilizing its excellent high-temperature oxidation resistance and thermal expansion matching with the Ni-based high-temperature alloy substrate, the peeling or detachment problem caused by the difference in thermal expansion coefficient between the ceramic coating and the alloy is effectively solved, thus achieving the goal of long-term service at high temperatures.

[0016] (2) The present invention uses a Ni / Ti dual-element co-doped spinel absorption layer. Compared with single-element doping, dual doping can synergistically control the spinel band structure. The introduction of Ti can further broaden the absorption band, while Ni can improve the high-temperature phase stability. The synergistic effect of the two significantly improves the spectral selectivity and thermal stability of the coating.

[0017] (3) The present invention uses radio frequency magnetron sputtering technology to deposit an absorption layer, and achieves in-situ doping by co-sputtering with dual targets (Ni target and Ti target). Furthermore, the doping concentration is gradient-distributed along the coating thickness direction by linearly increasing the power, thereby optimizing the light absorption path.

[0018] (4) In this invention, a composite antireflection layer of SiO2 inner layer and Al2O3 outer layer is prepared sequentially above the absorption layer. By utilizing the gradient change of the refractive index of the two materials, surface reflection is effectively reduced and light incident and absorption efficiency is increased.

[0019] (5) The present invention adopts a combination of three processes: plasma spraying, magnetron sputtering and sol-gel impregnation and lifting, giving full play to the advantages of each process: plasma spraying is highly efficient in preparing thick adhesive layers, magnetron sputtering is highly accurate and dense in preparing absorption layers, and sol-gel method is low cost and easy to control in preparing antireflection layers.

[0020] (6) The present invention adopts a three-stage heat treatment process: the low temperature stage removes organic residues, the medium temperature stage achieves preliminary crystallization of spinel, and the high temperature stage completes full crystallization and densification. The synergistic effect of each stage ensures the optimization of the coating structure and performance. Detailed Implementation

[0021] To better understand the above technical solutions, the technical solutions of the embodiments of this application will be described in detail below through specific embodiments. It should be understood that the embodiments of this application and the specific features in the embodiments are detailed descriptions of the technical solutions of the embodiments of this application, rather than limitations on the technical solutions of this application. In the absence of conflict, the embodiments of this application and the technical features in the embodiments can be combined with each other.

[0022] Example 1 This embodiment describes the preparation of a multilayer composite high-temperature resistant solar selective absorption coating on a Ni-based superalloy. The composition of the Ni-based superalloy substrate is as follows by mass percentage: Cr 5.5%, W 26%, Mo 1%, Ti 0.7%, C 0.03%, Ni balance. The sample size is 20mm × 25mm × 2mm.

[0023] A method for preparing a multilayer composite high-temperature resistant selective solar energy absorption coating includes the following steps: (1) Pretreatment of the substrate: The substrate was polished with 150#, 400# and 600# SiC sandpaper in sequence, and sandblasted with 150 mesh alumina to a roughness of Ra 6μm. Then it was ultrasonically cleaned in deionized water, anhydrous ethanol and acetone for 12min each in sequence, and dried for later use.

[0024] (2) Preparation of NiCrAlY bonding layer: NiCrAlY coating (by weight percentage, Cr 20%, Al 10%, Y 0.5%, Ni balance) was deposited using an APS-2000 plasma spraying equipment. The process parameters were: spraying distance 105mm, voltage 75V, current 550A, hydrogen flow rate 45L / min, argon flow rate 7L / min, powder feed rate 18rad / min, and coating thickness controlled at 52μm. After spraying, diffusion annealing was carried out at 650℃ for 1.5h under vacuum.

[0025] (3) Preparation of infrared reflective layer: Tetraethyl orthosilicate, anhydrous ethanol and deionized water were mixed in a molar ratio of 1:8:2, and dilute hydrochloric acid was added dropwise to adjust the pH to 3.5. The mixture was stirred in a water bath at 35°C for 3 hours and aged for 72 hours to obtain SiO2 sol. The SiO2 sol and Al powder were mixed evenly at a weight ratio of 1:2.5. The mixture was deposited on the adhesive layer at a speed of 2 mm / s using the dip-coating method. The wet film was dried at 30°C for 30 minutes and then dried at 150°C for 20 minutes.

[0026] (4) Preparation of composite absorber layer: Ceramic target preparation: CuO, Co2O3, and MnO2 powders were mixed in a molar ratio of Cu:Co:Mn = 3:1:3. NiO powder (5% of the total mass of metal cations) and TiO2 powder (7% of the total mass of metal cations) were added. The mixture was ball-milled for 6 hours, granulated, sieved, and then cold isostatically pressed under a pressure of 20 MPa. The mixture was first held at 550℃ for 3 hours, and then sintered at 1100℃ for 2.5 hours to obtain Ni / Ti double-doped spinel ceramic target.

[0027] Absorption layer deposition: The substrate is placed on the rotating sample holder of the RF magnetron sputtering system, heated to 550°C, and evacuated to 3×10⁻⁶. -4 Pa, Ar and O2 (flow ratio 3:1) were introduced, and the working pressure was 5 Pa; the ceramic target power supply was turned on and the power was set to 750 W; the pure Ni target and pure Ti target power supplies were turned on simultaneously, with the Ni target power linearly increasing from 90 W to 140 W (k=0.6) and the Ti target power linearly increasing from 110 W to 160 W (k=0.7); the sample holder rotation speed was 8 r / min, the sputtering time was 75 min, and the coating thickness was approximately 6.5 μm.

[0028] (5) Preparation of antireflective layer: SiO2 inner layer: Tetraethyl orthosilicate, anhydrous ethanol, and hydrochloric acid solution were mixed in a weight ratio of 1:10:0.8 and stirred at 30°C for 4 hours. After aging for 6 days, SiO2 sol was obtained. The sol was deposited on the absorber layer using the dip-coating method at a speed of 1.5 mm / s. The wet film was first dried at 28°C and then dried at 130°C to obtain a SiO2 layer with a thickness of about 100 nm.

[0029] Al2O3 outer layer: Using aluminum isopropoxide as a precursor, aluminum isopropoxide (aluminum isopropoxide:water = 1:450 molar ratio) was slowly added to deionized water at 85℃, and stirred at high speed for 3.5h to allow it to fully hydrolyze. The pH was adjusted to 3.5 with dilute nitric acid, and the mixture was allowed to stand to form an Al2O3 sol. The film was coated at a speed of 1.5mm / s and dried under the same conditions to obtain an Al2O3 layer with a thickness of about 80nm.

[0030] (6) Three-stage heat treatment: First stage: Increase the temperature to 300℃ at a rate of 6℃ / min and hold for 20min; Second stage: Increase to 550℃ at 5℃ / min and hold for 30min; The third stage: the temperature is increased to 780℃ at a rate of 4℃ / min, held for 36 hours, and then cooled to room temperature with the furnace.

[0031] Example 2 This embodiment describes the preparation of a multilayer composite high-temperature resistant solar selective absorption coating on a 304 stainless steel substrate. The sample size is 20mm × 25mm × 1.5mm.

[0032] A method for preparing a multilayer composite high-temperature resistant selective solar energy absorption coating includes the following steps: (1) Pretreatment of the substrate: The substrate was polished with 150#, 400# and 600# SiC sandpaper in sequence, and sandblasted with 100 mesh alumina to a roughness Ra 5.5μm. Then it was ultrasonically cleaned in deionized water, anhydrous ethanol and acetone for 10min each in sequence, and dried for later use.

[0033] (2) Preparation of NiCrAlY bonding layer: NiCrAlY bonding layer preparation: NiCrAlY coating (by weight percentage, Cr 20%, Al 9%, Y 0.5%, Ni balance) was deposited using an APS-2000 plasma spraying equipment. The process parameters were: spraying distance 100mm, voltage 70V, current 500A, hydrogen flow rate 35L / min, argon flow rate 6L / min, powder feed rate 15rad / min, and coating thickness controlled at 50μm. After spraying, diffusion annealing was carried out under vacuum at 600℃ for 2h.

[0034] (3) Preparation of infrared reflective layer: Tetraethyl orthosilicate, anhydrous ethanol and deionized water were mixed in a molar ratio of 1:8:2, and dilute hydrochloric acid was added dropwise to adjust the pH to 3.0. The mixture was stirred in a water bath at 30°C for 4 hours and aged for 96 hours to obtain SiO2 sol. The SiO2 sol and Al powder were mixed evenly at a weight ratio of 1:2.5. The film was deposited on the adhesive layer at a speed of 1.5 mm / s using the dip-coating method. The wet film was dried at 25°C for 40 minutes and then dried at 120°C for 30 minutes.

[0035] (4) Preparation of composite absorber layer: Ceramic target preparation: CuO, Co2O3, and MnO2 powders were mixed in a molar ratio of Cu:Co:Mn = 3:1:3. NiO powder (3% of the total mass of metal cations) and TiO2 powder (5% of the total mass of metal cations) were added. The mixture was ball-milled for 5 hours, granulated, sieved, and then cold isostatically pressed under a pressure of 15 MPa. The mixture was first held at 500℃ for 4 hours, and then sintered at 1000℃ for 3 hours to obtain Ni / Ti double-doped spinel ceramic target.

[0036] Absorption layer deposition: The substrate is placed on the rotating sample holder of the RF magnetron sputtering system, heated to 500°C, and evacuated to 2×10⁻⁶. -4 Pa, Ar and O2 (flow ratio 3:1) were introduced, and the working pressure was 4 Pa; the ceramic target power supply was turned on and the power was set to 700 W; the pure Ni target and pure Ti target power supplies were turned on simultaneously, with the Ni target power linearly increasing from 80 W to 130 W (k=0.5) and the Ti target power linearly increasing from 100 W to 150 W (k=0.6); the sample holder rotation speed was 5 r / min, the sputtering time was 90 min, and the coating thickness was approximately 5.2 μm.

[0037] (5) Preparation of antireflective layer: SiO2 inner layer: Tetraethyl orthosilicate, anhydrous ethanol, and hydrochloric acid solution were mixed in a weight ratio of 1:10:0.8 and stirred at 25°C for 5 hours. After aging for 5 days, SiO2 sol was obtained. The sol was deposited on the absorber layer using the dip-coating method at a speed of 1.2 mm / s. The wet film was first dried at 25°C and then dried at 120°C to obtain a SiO2 layer with a thickness of approximately 80 nm.

[0038] Al2O3 outer layer: Using aluminum isopropoxide as a precursor, aluminum isopropoxide (aluminum isopropoxide:water = 1:400 molar ratio) was slowly added to deionized water at 80℃, and stirred at high speed for 4h to allow it to be fully hydrolyzed. The pH was adjusted to 3.0 with dilute nitric acid, and the mixture was allowed to stand to form an Al2O3 sol. The film was coated at a speed of 1.2mm / s and dried under the same conditions to obtain an Al2O3 layer with a thickness of about 60nm.

[0039] (6) Three-stage heat treatment: First stage: Increase the temperature to 250℃ at a rate of 5℃ / min and hold for 30min; Second stage: Increase the temperature to 500℃ at a rate of 4℃ / min and hold for 40min; The third stage: the temperature is increased to 750℃ at a rate of 3℃ / min, held for 48 hours, and then cooled to room temperature in the furnace.

[0040] Example 3 This embodiment describes the preparation of a multilayer composite high-temperature resistant solar selective absorption coating on a Ni-based high-temperature alloy. The Ni-based high-temperature alloy substrate used is the same as that in Example 1.

[0041] A method for preparing a multilayer composite high-temperature resistant selective solar energy absorption coating includes the following steps: (1) Pretreatment of the substrate: The substrate was polished with 150#, 400# and 600# SiC sandpaper in sequence, and sandblasted with 220 mesh alumina to a roughness of Ra 7μm. Then it was ultrasonically cleaned in deionized water, anhydrous ethanol and acetone for 15min each, and dried for later use.

[0042] (2) Preparation of NiCrAlY bonding layer: NiCrAlY coating (by weight percentage, Cr 22%, Al 10%, Y 0.7%, Ni balance) was deposited using an APS-2000 plasma spraying equipment. The process parameters were: spraying distance 110mm, voltage 80V, current 600A, hydrogen flow rate 50L / min, argon flow rate 9L / min, powder feed rate 20rad / min, and coating thickness controlled at 55μm. After spraying, diffusion annealing was carried out at 700℃ for 1h under vacuum.

[0043] (3) Preparation of infrared reflective layer: Tetraethyl orthosilicate, anhydrous ethanol and deionized water were mixed in a molar ratio of 1:8:2, and dilute hydrochloric acid was added dropwise to adjust the pH to 4.0. The mixture was stirred in a water bath at 40°C for 2 hours and aged for 48 hours to obtain SiO2 sol. The SiO2 sol and Al powder were mixed evenly at a weight ratio of 1:2.5. The film was deposited on the adhesive layer at a speed of 2.5 mm / s using the dip-coating method. The wet film was dried at 35°C for 20 minutes and then dried at 160°C for 15 minutes.

[0044] (4) Preparation of composite absorber layer: Ceramic target preparation: CuO, Co2O3, and MnO2 powders were mixed in a molar ratio of Cu:Co:Mn = 3:1:3. NiO powder (7% of the total mass of metal cations) and TiO2 powder (10% of the total mass of metal cations) were added. The mixture was ball-milled for 7 hours, granulated and sieved, and then cold isostatically pressed under a pressure of 25 MPa. The mixture was first held at 600℃ for 2 hours, and then sintered at 1200℃ for 2 hours to obtain Ni / Ti double-doped spinel ceramic target.

[0045] Absorption layer deposition: The substrate is placed on the rotating sample holder of the RF magnetron sputtering system, heated to 600°C, and evacuated to 5×10⁻⁶. -4Pa, Ar and O2 (flow ratio 3:1) were introduced, and the working pressure was 6 Pa; the ceramic target power supply was turned on and the power was set to 800 W; the pure Ni target and pure Ti target power supplies were turned on simultaneously, with the Ni target power linearly increasing from 100 W to 150 W (k=0.7) and the Ti target power linearly increasing from 120 W to 170 W (k=0.8); the sample holder rotation speed was 10 r / min, the sputtering time was 60 min, and the coating thickness was approximately 7.8 μm.

[0046] (5) Preparation of antireflective layer: SiO2 inner layer: Tetraethyl orthosilicate, anhydrous ethanol, and hydrochloric acid solution were mixed in a weight ratio of 1:10:0.8 and stirred at 35°C for 3 hours. After aging for 7 days, SiO2 sol was obtained. The sol was deposited on the absorber layer using the dip-coating method at a speed of 1.8 mm / s. The wet film was first dried at 30°C and then dried at 140°C to obtain a SiO2 layer with a thickness of approximately 120 nm.

[0047] Al2O3 outer layer: Using aluminum isopropoxide as a precursor, aluminum isopropoxide (aluminum isopropoxide:water = 1:500 molar ratio) was slowly added to deionized water at 90℃, and stirred at high speed for 3 hours to allow it to fully hydrolyze. The pH was adjusted to 4.0 with dilute nitric acid, and the mixture was allowed to stand to form an Al2O3 sol. The film was coated at a speed of 1.8 mm / s and dried under the same conditions to obtain an Al2O3 layer with a thickness of about 100 nm.

[0048] (6) Three-stage heat treatment: First stage: Increase the temperature to 350℃ at a rate of 8℃ / min and hold for 15min; Second stage: Increase to 600℃ at 6℃ / min and hold for 20min; The third stage: the temperature is increased to 800℃ at a rate of 5℃ / min, held for 24 hours, and then cooled to room temperature in the furnace.

[0049] The coatings prepared in Examples 1-3 had their absorptivity tested using a UV-Vis-NIR spectrophotometer and their emissivity tested using a Fourier transform infrared spectrometer. Their thermal stability was also tested after being incubated at 800°C in air for 100 hours. The test results for each example are shown in Table 1.

[0050] Table 1. Test results of coating thickness, optical properties, and thermal stability in Examples 1-3.

[0051] The test results in Table 1 show that: (1) The multilayer composite high-temperature solar selective absorption coatings prepared in Examples 1-3 all achieved a deposition-state absorptivity of over 0.915 under atmospheric quality factor AM1.5, with Example 3 reaching as high as 0.941; and an emissivity of less than 0.170, with Example 3 as low as 0.145. This indicates that the coating of the present invention has excellent spectral selectivity.

[0052] (2) After annealing at 800°C in air for 100 hours, the absorptivity and emissivity of each embodiment changed very little. The absorptivity changed by only -0.003 and the emissivity changed by +0.004 to +0.006, indicating that the coating has excellent thermal stability and high-temperature oxidation resistance at high temperatures.

[0053] (3) After annealing, the macroscopic morphology of the coatings in each embodiment remained intact, without peeling or flaking, indicating that the NiCrAlY bonding layer effectively alleviated the thermal expansion mismatch between the ceramic coating and the metal substrate.

[0054] (4) Comparing Examples 1, 2 and 3, it can be seen that appropriately increasing the doping amount of Ni and Ti (Ni 7% and Ti 10% in Example 3) helps to improve the absorption rate of the coating, which may be related to the synergistic optimization of the spinel band structure by dual doping.

[0055] It will be readily understood by those skilled in the art that the above-described advantageous methods can be freely combined and superimposed without conflict. The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application. The above are merely preferred embodiments of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of this application, and these improvements and modifications should also be considered within the protection scope of this application.

Claims

1. A multilayer composite high-temperature resistant selective solar energy absorption coating, characterized in that: In order, they include: A bonding transition layer, an infrared reflective layer, a composite absorption layer, and an antireflective layer are prepared on a metal substrate; wherein, The bonding transition layer is a NiCrAlY alloy layer; The infrared reflective layer is an Al-SiO2 composite layer; The composite absorber layer is a Ni / Ti dual-doped CuCoMnOx spinel layer; The antireflective layer is a SiO2-Al2O3 composite layer.

2. The multilayer composite high-temperature solar selective absorption coating according to claim 1, characterized in that: The chemical composition of the NiCrAlY alloy, by mass percentage, is: Cr 20%~25%, Al 5%~10%, Y 0.5%~1.0%, with the remainder being Ni.

3. The multilayer composite high-temperature solar selective absorption coating according to claim 1, characterized in that: In the infrared reflective layer, the mass ratio of SiO2 sol to Al powder is 1:(2~3).

4. The multilayer composite high-temperature solar selective absorption coating according to claim 1, characterized in that: In the composite absorber layer, the Ni doping amount is 3% to 7% of the total mass of the CuCoMnOx spinel matrix metal cations, and the Ti doping amount is 5% to 10% of the total mass of the metal cations.

5. The multilayer composite high-temperature solar selective absorption coating according to claim 1, characterized in that: The antireflection layer is composed of an inner SiO2 layer and an outer Al2O3 layer. The thickness of the SiO2 layer is 80nm~120nm, and the thickness of the Al2O3 layer is 60nm~100nm.

6. The method for preparing the multilayer composite high-temperature resistant solar selective absorption coating according to any one of claims 1 to 5, characterized in that, Includes the following steps: Step 1: Pre-treat the metal substrate; Step 2: Deposit a NiCrAlY alloy layer on the metal substrate as a bonding transition layer, and then perform vacuum diffusion annealing. Step 3: Prepare SiO2 sol, mix it with Al powder, and then use the dip-coating method to prepare an infrared reflective layer on the bonding transition layer; Step 4: Prepare Ni / Ti dual-doped CuCoMnOx spinel ceramic target, and deposit a composite absorption layer on the infrared reflective layer using radio frequency magnetron sputtering technology; Step 5: Prepare SiO2 sol and Al2O3 sol respectively, and then use the dip-coating method to prepare the inner SiO2 layer and the outer Al2O3 layer on the composite absorption layer to form an anti-reflection layer. Step 6: Heat treat the resulting coating.

7. The preparation method according to claim 6, characterized in that: In step 2, the process parameters for depositing the NiCrAlY coating using atmospheric plasma spraying technology are as follows: spraying distance 100mm~110mm, voltage 70V~80V, current 500A~600A, hydrogen flow rate 35L / min~50L / min, argon flow rate 6L / min~9L / min, powder feed rate 15rad / min~20rad / min, and coating thickness controlled at 50μm~55μm. The vacuum diffusion annealing temperature is 600℃~700℃, and the holding time is 1h~2h.

8. The preparation method according to claim 6, characterized in that: Step 4, the preparation method of the Ni / Ti dual-doped CuCoMnOx spinel ceramic target, includes: CuO, Co2O3, and MnO2 powders were mixed in a molar ratio of Cu:Co:Mn = 3:1:

3. NiO powder and TiO2 powder were added, and the mixture was ball-milled for 5 to 7 hours. After granulation and sieving, the mixture was cold isostatically pressed under a pressure of 15 MPa to 25 MPa. The mixture was then held at 500℃ to 600℃ for 2 to 4 hours, and then sintered at 1000℃ to 1200℃ for 2 to 3 hours.

9. The preparation method according to claim 6, characterized in that: In step 4, the process parameters for depositing the composite absorber layer using radio frequency magnetron sputtering technology are as follows: substrate heating to 500℃~600℃, vacuum degree 2×10 -4 Pa~5×10 -4 Pa, Ar and O2 are introduced, working pressure is 4Pa~6Pa, ceramic target power is 700W~800W, pure Ni target power increases linearly from 80W~100W to 130W~150W, pure Ti target power increases linearly from 100W~120W to 150W~170W, sample holder rotation speed is 5r / min~10r / min, sputtering time is 60~90min.

10. The preparation method according to claim 6, characterized in that: In step 6, the heat treatment method includes: First stage: Increase the temperature to 250℃~350℃ at a rate of 5℃ / min~8℃ / min, and hold for 15min~30min; Second stage: Increase the temperature to 500℃~600℃ at a rate of 4℃ / min~6℃ / min, and hold for 20min~40min; The third stage: the temperature is increased to 750℃~800℃ at a rate of 3℃ / min~5℃ / min, held for 24h~48h, and then cooled to room temperature with the furnace.

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