Multi-layer insulation structure for high-temperature thin film sensor and preparation method and application of multi-layer insulation structure

Abstract

The invention discloses a multi-layer insulation structure for a high-temperature thin film sensor and a preparation method and application thereof, and belongs to the technical field of thin film materials. The multi-layer insulation structure sequentially comprises a metal substrate, a NiCrAlY transition layer, an alpha-Al2O3 layer, an amorphous Al2O3 layer and a CeO2 / HfO2 heterogeneous lamination layer along the lamination direction; the preparation method comprises the following steps: pretreating the surface of the metal substrate; depositing a NiCrAlY transition layer on the surface of the pretreated metal substrate by adopting a magnetron sputtering method; an alpha-Al2O3 layer is generated on the upper surface of the NiCrAlY transition layer; putting the three-layer structure into atomic layer deposition equipment, and preparing an amorphous Al2O3 layer on the surface of the alpha-Al2O3 layer by using an ALD (atomic layer deposition) process; and preparing the CeO2 / HfO2 heterogeneous lamination layer on the surface of the amorphous Al2O3 layer by adopting a magnetron sputtering method. Microdefects such as cracks can be prevented, and the high-temperature reliability is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of thin film materials, and in particular relates to a multi-layer insulation structure for high-temperature thin film sensors, a preparation method thereof, and applications thereof. Background Art

[0002] Hot-end components of high-end equipment in aerospace, nuclear, and other industries operate under extreme conditions of high temperature, high pressure, and strong vibration for extended periods. Accurate monitoring of parameters such as temperature and strain is crucial for fault warning and operational safety. Traditional temperature and strain sensors, such as thin-film thermocouples and wire-grid strain gauges, struggle to meet current measurement requirements due to their limited temperature tolerance, invasive mounting methods, and low frequency response.

[0003] Thin-film sensors fabricated using micro-nanofabrication technologies offer the advantages of high spatiotemporal resolution and non-invasive integration, making them widely used for thermal parameter monitoring in aerospace hot-end components. The insulating layer, a key component in ensuring sensor measurement accuracy, prevents electrical conduction between the sensitive thin film and the component being measured. However, conventional single-layer insulation systems suffer from extreme high-temperature environments. Micro-defects such as film recrystallization, cracks, and voids can create electrical conduction to ground, causing an exponential decrease in insulation resistance and leading to significant measurement errors. Previous YSZ / Al2O3 stacked structures have limited their application above 800°C due to the ionic conductivity of YSZ at high temperatures. The YSZ-based insulating layer fails at temperatures above 800°C due to oxygen vacancies. SiN / Al2O3 stacked structures, however, experience delamination failure under thermal shock due to mismatched thermal expansion coefficients, limiting their further application. Furthermore, the manufacturing process for the multilayered, repetitive insulating structures disclosed in prior art is complex.

[0004] In response to the above technical defects, the present invention proposes a multi-layer insulation structure for thin-film sensors for high-temperature extreme environments. Thermal stress gradient design is achieved through material optimization, and the generation of micro-defects is prevented through the heterogeneous stacked structure of amorphous Al2O3 and metal oxides, thereby improving its high-temperature insulation performance. Summary of the Invention

[0005] Technical issues to be solved:

[0006] In order to avoid the shortcomings of the existing technology, the present invention provides a multi-layer insulation structure for high-temperature thin-film sensors, as well as its preparation method and application. Based on amorphous aluminum oxide, the thermal expansion coefficient of the transition layer and the insulation layer are matched to prevent the generation of micro-defects such as cracks. Based on the metal oxide heterogeneous stacked structure, the electrical signal is prevented from being conducted to the ground, thereby improving high-temperature reliability.

[0007] The technical solution of the present invention is: a multilayer insulation structure for high-temperature thin-film sensors, which includes a metal substrate, a NiCrAlY transition layer, an α-Al2O3 layer, an amorphous Al2O3 layer, and a CeO2 / HfO2 heterogeneous stack in sequence along the stacking direction. The CeO2 / HfO2 heterogeneous stack is a periodic interface barrier, which is alternately deposited in the order of CeO2 / HfO2, and ensures that the CeO2 layer is adjacent to the amorphous Al2O3 layer and the HfO2 layer is located on the top surface; wherein the thickness ratio of the CeO2 layer to the HfO2 layer is ≤2.6:1, the thickness of the CeO2 single layer is ≤1.3μm, the thickness of the HfO2 single layer is ≤0.5μm, and the overall thickness of the CeO2 / HfO2 heterogeneous stack is ≥1.8μm.

[0008] A further technical solution of the present invention is: the thickness of the metal substrate is 50 to 100 μm; the thickness of the NiCrAlY alloy transition layer is 10 to 50 μm, the thickness of the α-Al2O3 layer is 500 to 1000 nm, the thickness of the amorphous Al2O3 layer is 100 to 500 nm, and the thickness of the CeO2 / HfO2 heterogeneous stack is 1800 to 5400 nm.

[0009] A further technical solution of the present invention is: the metal substrate is a nickel-based high-temperature alloy substrate.

[0010] A method for preparing a multilayer insulation structure for a high-temperature thin-film sensor, comprising the following steps:

[0011] Pre-treating the surface of the metal substrate by polishing, cleaning and drying;

[0012] A NiCrAlY film is deposited on the surface of a pretreated metal substrate by using a DC magnetron sputtering method as a NiCrAlY transition layer;

[0013] An α-Al2O3 layer is formed on the upper surface of the NiCrAlY transition layer by using an aluminum precipitation oxidation process;

[0014] The metal substrate covered with the NiCrAlY transition layer and the α-Al2O3 layer is cleaned to obtain a three-layer structure;

[0015] The cleaned three-layer structure was placed in an atomic layer deposition device, and an amorphous Al2O3 layer was prepared on the surface of the α-Al2O3 layer using the ALD process;

[0016] CeO2 / HfO2 heterojunction layers were prepared on the surface of amorphous Al2O3 layer by magnetron sputtering.

[0017] A further technical solution of the present invention is: the pretreatment method of the metal substrate is: first, the surface of the substrate is ground and polished, then it is immersed in acetone, anhydrous ethanol and deionized water in sequence for ultrasonic cleaning, and finally it is blown dry with nitrogen and dried on a heating table for use.

[0018] A further technical solution of the present invention is: the method for generating the α-Al2O3 layer is:

[0019] The metal substrate with the NiCrAlY transition layer deposited thereon is placed in a tube furnace;

[0020] Heat the furnace to 950-1050℃ and keep it warm for 4-6 hours to precipitate the metallic aluminum;

[0021] After cooling to 850-950℃, oxygen is introduced to oxidize the precipitated aluminum. The oxygen purity is not less than 99.995% and the oxidation time is 5-12 hours.

[0022] The α-Al2O3 layer is obtained by cooling the furnace to room temperature;

[0023] Among them, the aluminum precipitation oxidation process is 8×10 -4 The oxidation process is completed under a vacuum environment of Pa, and the oxygen pressure in the oxidation process is 100Pa.

[0024] A further technical solution of the present invention is: the method for cleaning the metal substrate covered with the NiCrAlY transition layer and the α-Al2O3 layer is to immerse it in acetone, anhydrous ethanol and deionized water in sequence for ultrasonic cleaning, blow it dry with nitrogen, and dry it on a heating table for later use.

[0025] A further technical solution of the present invention is: the preparation method of the amorphous Al2O3 layer uses trimethylaluminum (TMA) and oxygen plasma as precursors, water as an oxidant, and is prepared in a TMA nitrogen cleaning-oxygen plasma nitrogen cleaning cycle; the duration of each cycle is 12 seconds, and the deposition temperature is 150°C.

[0026] A further technical solution of the present invention is that in the preparation of the CeO2 / HfO2 heterogeneous stack, CeO2 is prepared by DC reactive magnetron sputtering with an Ar / O2 ratio of 15:5-15:10 and a gas pressure of 0.3-0.6 Pa to improve its density. HfO2 is deposited by radio frequency magnetron sputtering to form an interface barrier with CeO2 and improve insulation resistance.

[0027] A multilayer insulation structure for high-temperature thin-film sensors is used in thin-film sensors for monitoring temperature and strain parameters of hot-end components of aerospace equipment. The insulation resistance of the multilayer insulation structure at 1000°C is not less than 100kΩ.

[0028] Beneficial effects

[0029] The beneficial effects of the present invention are as follows: the multi-layer insulation structure and preparation method provided by the present invention solve the core problem of insulation layer failure in high temperature environments through innovative material combination and process collaboration. The specific advantages are as follows:

[0030] 1. Under extreme operating conditions of 1000°C, the insulation resistance remains stable at ≥100kΩ, two orders of magnitude higher than traditional structures (such as YSZ / Al2O3 stacks), meeting the long-term monitoring requirements of hot-end components such as aircraft engine blades. The CeO2 / HfO2 heterogeneous stack forms an interfacial barrier that effectively inhibits high-temperature ion migration, eliminating the failure of the YSZ insulation layer at temperatures above 800°C caused by conductivity due to oxygen vacancies.

[0031] 2. In-situ thermal oxidation of the α-Al2O3 layer: Perfectly matches the coefficient of thermal expansion (CTE) of the nickel-based alloy substrate, avoiding delamination caused by CTE mismatch. Amorphous Al2O3 layer (ALD) seals the gap: The atomic layer deposition (ALD) process forms a pore-free film at a low temperature of 150°C, filling microcracks in the thermally grown α-Al2O3 layer and blocking low-temperature conductive paths.

[0032] 3. Sandwich protection mechanism:

[0033] α-Al2O3 layer (thermal oxidation) → matches the substrate CTE to prevent thermal shock delamination;

[0034] Amorphous Al2O3 layer (ALD) → fills micro defects and blocks leakage at medium and low temperatures;

[0035] CeO2 / HfO2 heterogeneous stack (sputtering) → interface barrier inhibits high-temperature ionic conduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 Schematic diagram of a multi-layer insulation structure for high-temperature thin-film sensors according to an embodiment of the present invention;

[0037] Figure 2 The insulation resistance curve of a traditional single insulation layer at high temperature varies with temperature;

[0038] Figure 3 The insulation resistance of the multi-layer insulation structure prepared in accordance with the embodiment of the present invention changes with temperature at high temperature;

[0039] Explanation of the reference numerals: 1. nickel-based high-temperature alloy substrate, 2. NiCrAlY transition layer, 3. α-Al2O3 layer, 4. amorphous Al2O3 layer, 5. heterogeneous laminate. DETAILED DESCRIPTION

[0040] The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present invention, but should not be construed as limiting the present invention.

[0041] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0042] Based on the oxygen vacancy conductivity problem of YSZ (failure at >800°C) and the columnar pore problem of electron beam evaporated Al2O3 in existing metal-based high-temperature composite insulation layers, the present invention provides a high-temperature multi-layer insulation structure for metal-based thin film sensors. By matching the thermal stress gradient through the multi-layer interface, delamination failure under thermal shock is prevented; the high-temperature multi-layer insulation structure comprises, from bottom to top: a metal substrate, a NiCrAlY alloy transition layer, an α-Al2O3 layer, an amorphous Al2O3 layer, and a CeO2 / HfO2 heterogeneous stack. The CeO2 / HfO2 heterogeneous stack is a periodic interface barrier, which is alternately deposited in the order of CeO2 / HfO2, and ensures that the CeO2 layer is adjacent to the amorphous Al2O3 layer and the HfO2 layer is located on the top surface; wherein, the thickness ratio of the CeO2 layer and the HfO2 layer is ≤2.6:1, the thickness of the CeO2 single layer is ≤1.3μm, the thickness of the HfO2 single layer is ≤0.5μm, and the overall thickness of the CeO2 / HfO2 heterogeneous stack is ≥1.8μm.

[0043] The α-Al2O3 layer is generated in situ through an aluminum precipitation oxidation process to match the transition layer and the insulating layer and prevent them from falling off. The amorphous Al2O3 layer is produced through atomic layer deposition (ALD) technology, with high density, filling the gaps and cracks in the thermally grown Al2O3 layer. The CeO2 in the CeO2 / HfO2 heterojunction is produced through DC reactive magnetron sputtering. By regulating the Ar / O2 ratio, temperature, and gas pressure, the density of the deposited film is optimized to ensure high insulation resistance. HfO2 is deposited using radio frequency magnetron sputtering to form an interface barrier with CeO2 to improve insulation resistance.

[0044] Preferably, the thickness of the metal substrate is 50 to 100 μm; the thickness of the NiCrAlY alloy transition layer 2 is 13 to 16 μm, the thickness of the α-Al2O3 layer 3 is 700 to 1000 nm, the thickness of the atomic layer deposited Al2O3 layer is 100 to 300 nm, and the thickness of the CeO2 / HfO2 heterogeneous stack 5 is 1800 to 5400 nm.

[0045] The present invention also provides a method for preparing a multilayer insulation structure for a high-temperature thin film sensor, comprising the following steps:

[0046] Step 1. Surface treatment of metal substrate: First, the substrate surface is ground and polished, then immersed in acetone, anhydrous ethanol and deionized water for ultrasonic cleaning, and finally blown dry with nitrogen and dried on a heating table for later use.

[0047] Step 2. Preparation of alloy transition layer: A layer of NiCrAlY thin film is deposited on the metal substrate prepared in step 1 by DC magnetron sputtering as a transition layer.

[0048] Step 3. Preparation of α-Al2O3 layer: Place the substrate prepared in step 2 into a tube furnace, keep it at high temperature to precipitate metallic aluminum, then cool it down and introduce oxygen into the tube furnace while keeping it at high temperature to oxidize the precipitated aluminum, and finally cool it down to room temperature to obtain the α-Al2O3 layer. -4 Pa vacuum environment, heat preservation at 950-1050℃; oxidation temperature is 850-950℃, while air / pure oxygen is introduced and heat preservation is guaranteed at 100Pa pressure.

[0049] Step 4. Cleaning before preparing the insulating layer: After completing step 3, the substrate is ultrasonically cleaned in acetone / anhydrous ethanol / deionized water in sequence, blown dry with nitrogen, and dried on a heating table for later use.

[0050] Step 5. Preparation of amorphous Al2O3 layer: A layer of amorphous Al2O3 is prepared on the substrate after completing step 4 using the atomic layer deposition method, with a deposition temperature of 300-500°C.

[0051] Step 6. Preparation of CeO2 / HfO2 heterogeneous stack: Prepare CeO2 layer on the substrate prepared in step 5 by reactive DC magnetron sputtering, using 99.99% purity Ce target and vacuum degree 8x10 -4 Pa, Ar / O2 ratio of 15:5-15:10, sputtering power 300W, working pressure 0.3-0.6Pa, sputtering to obtain a 1000-1400nm thick CeO2 layer; then the HfO2 layer was prepared by radio frequency magnetron sputtering, using 99.99% pure HfO2 target material, vacuum degree 8×10 -4 Pa, argon environment, sputtering power 210W, working pressure 0.4-0.6 Pa. Complete the preparation of the entire multi-layer insulation structure.

[0052] Preferably, the aluminum precipitation temperature in step 3 is 950-1050°C, preferably 1000°C; the oxidation temperature is 850-950°C, preferably 900°C.

[0053] Preferably, the oxidizing gas environment in step 3 is air / pure oxygen, preferably pure oxygen, with a purity of no less than 99.995%.

[0054] Preferably, in step 3, the aluminum precipitation time is 4 to 8 hours, preferably 6 hours; the oxidation time is 8 to 14 hours, preferably 12 hours.

[0055] To address the rapid drop in insulation resistance caused by recrystallization defects in traditional single-layer insulation structures at high temperatures, this paper proposes a multilayer heterogeneous insulation structure for high-temperature thin-film sensors. This design achieves a thermal stress gradient by optimizing material selection. Amorphous aluminum oxide is used to match the thermal expansion coefficients of the transition layer and the insulation layer to prevent the formation of micro-defects such as cracks. The metal oxide heterogeneous stack structure prevents electrical signal conduction to ground, improving high-temperature reliability. This multilayer insulation structure for high-temperature thin-film sensors can maintain excellent insulation performance of 100kΩ at 1000°C, an improvement of approximately two orders of magnitude compared to traditional structures, ensuring the reliable operation of high-temperature thin-film devices under extreme operating conditions.

[0056] The following is a further analysis of the above technical solution with reference to examples and drawings.

[0057] In one embodiment, referring to Figure 1 As shown, in this embodiment, a multilayer insulation structure for a high-temperature thin film sensor includes a nickel-based high-temperature alloy substrate, a NiCrAlY transition layer, an α-Al2O3 layer, an amorphous Al2O3 layer, and a CeO2 / HfO2 heterogeneous stack in the stacking direction. In the CeO2 / HfO2 heterogeneous stack, the CeO2 layer is deposited first, and then the HfO2 layer is deposited on the first CeO2 layer. CeO2 / HfO2 are alternately deposited in this order to form a periodic interface barrier, and HfO2 is located on the top surface of the multilayer insulation structure. The thickness ratio of the CeO2 layer to the HfO2 layer does not exceed 2.6:1, the thickness of the CeO2 single layer does not exceed 1.3μm, the thickness of the HfO2 single layer does not exceed 0.5μm, and the thickness of the heterogeneous stack is ≥1.8μm.

[0058] Specifically, the thickness of the nickel-based high-temperature alloy substrate 1 is 80 μm; the thickness of the NiCrAlY alloy transition layer is 12 to 15 μm, the thickness of the α-Al2O3 layer is 1000 nm, the thickness of the amorphous Al2O3 layer is 100 nm, and the thickness of the CeO2 / HfO2 heterogeneous stack is 1800 nm.

[0059] In one embodiment, a method for preparing a multi-layer insulation structure for a high-temperature thin-film sensor includes the following specific steps:

[0060] Step 1. Surface treatment of the substrate: Use high-temperature alloy GH4099 as the substrate material with a thickness of 80 μm. First, use diamond sandpaper to polish from 160 mesh to 2000 mesh to remove surface oxides, then immerse in acetone, anhydrous ethanol and deionized water for ultrasonic cleaning, and finally blow dry with nitrogen and use a heating table to dry for later use.

[0061] Step 2. Preparation of alloy transition layer: Cut the cleaned substrate into 20×30 mm sheets. Place the substrate into a magnetron sputtering machine and use NiCrAlY target (67% Ni 22% Cr 10% Al 1% Y) for DC magnetron sputtering. The background vacuum is 5×10 -4 Pa, argon gas was introduced, the working pressure was 0.3 Pa, and a NiCrAlY layer with a thickness of 12-15 μm was obtained by deposition for 6 hours.

[0062] Step 3. Preparation of α-Al2O3 layer: Place the substrate completed in step 2 into a tube furnace and evacuate to a background vacuum of 8×10 -4 Pa, and then the temperature was raised to 1000℃ at a rate of 5℃ / min and kept for 6 hours to precipitate Al; after that, the temperature was lowered to 900℃ and kept warm. At this time, the molecular pump system was turned off, pure oxygen was introduced and the pressure was maintained at 100Pa using a pressure controller, and the oxidation was completed by keeping warm for 12 hours to obtain a 1μm oxide layer.

[0063] Step 4. Cleaning before preparing the insulating layer: After completing step 3, the substrate is ultrasonically cleaned in acetone / anhydrous ethanol / deionized water in sequence, blown dry with nitrogen, and dried on a heating table for later use.

[0064] Step 5. Preparation of an amorphous Al2O3 layer: A dense Al2O3 layer was deposited on the substrate prepared in Step 4 using plasma-enhanced atomic layer deposition (PEALD). Trimethylaluminum (TMA) and oxygen plasma were used as precursors, and water was used as the oxidant. The deposition process involved a TMA nitrogen purge followed by an oxygen plasma nitrogen purge. Each cycle lasted 12 seconds, and the deposition temperature was 150°C. The resulting ALD film exhibited high quality and uniformity, resulting in a 100nm thick Al2O3 film.

[0065] Step 6. Preparation of CeO2 / HfO2 heterogeneous stack: CeO2 layer was prepared on the substrate prepared in step 5 by DC magnetron sputtering, using 99.99% purity Ce target material and vacuum degree of 8×10 -4 Pa, Ar / O2 ratio of 15:5, sputtering power 300W, working pressure 0.3-0.6Pa, sputtering to obtain a 1.3μm thick CeO2 layer; then the HfO2 layer was prepared by radio frequency magnetron sputtering method, using 99.99% pure HfO2 target material, vacuum degree 8×10 -4Pa, argon environment, sputtering power 210W, working pressure 0.5 Pa, to obtain a 0.5μm thick HfO2 layer. The preparation of the entire multi-layer insulation structure is completed.

[0066] In practical applications, those skilled in the art can adjust the thickness of the transition layer and the insulating layer according to actual application conditions.

[0067] In order to verify the high-temperature stability and insulation reliability of the composite insulation layer structure of the present invention, a high-temperature resistance test was performed on the composite insulation layer prepared in the example to obtain a resistance-temperature curve. Figure 3 It can be seen that the insulation layer shows good insulation performance in the range of room temperature to 1000℃, and can maintain an insulation resistance of ≥100kΩ at 1000℃. Figure 2 The insulation resistance of a traditional single-layer insulation layer is only 2kΩ at 1000°C, which fully meets the insulation requirements under extreme high-temperature working conditions and can be used in thin-film sensors.

[0068] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and purpose of the present invention.

Claims

1. A multi-layer insulation structure for high-temperature thin-film sensors, characterized by: Along the stacking direction, it includes a metal substrate, a NiCrAlY transition layer, an α-Al2O3 layer, an amorphous Al2O3 layer, and a CeO2 / HfO2 heterogeneous stack. The CeO2 / HfO2 heterogeneous stack is a periodic interface barrier and is alternately deposited in the order of CeO2 / HfO2, and ensures that the CeO2 layer is adjacent to the amorphous Al2O3 layer and the HfO2 layer is located on the top surface; wherein the thickness ratio of the CeO2 layer to the HfO2 layer is ≤2.6:1, the thickness of the CeO2 single layer is ≤1.3μm, the thickness of the HfO2 single layer is ≤0.5μm, and the overall thickness of the CeO2 / HfO2 heterogeneous stack is ≥1.8μm.

2. The multi-layer insulation structure for high-temperature thin-film sensors according to claim 1, characterized in that: The thickness of the metal substrate is 50-100 μm; the thickness of the NiCrAlY alloy transition layer is 10-50 μm, the thickness of the α-Al2O3 layer is 500-1000 nm, the thickness of the amorphous Al2O3 layer is 100-500 nm, and the thickness of the CeO2 / HfO2 heterogeneous stack is 1800-5400 nm.

3. The multi-layer insulation structure for high-temperature thin-film sensors according to claim 1, characterized in that: The metal substrate is a nickel-based high-temperature alloy substrate.

4. A method for preparing a multilayer insulation structure for a high-temperature thin film sensor according to any one of claims 1 to 3, characterized in that The specific steps are as follows: Pre-treating the surface of the metal substrate by polishing, cleaning and drying; A NiCrAlY film is deposited on the surface of the pretreated metal substrate by magnetron sputtering as a NiCrAlY transition layer; An α-Al2O3 layer is grown on the upper surface of the NiCrAlY transition layer using an aluminum precipitation oxidation process; The metal substrate covered with the NiCrAlY transition layer and the α-Al2O3 layer is cleaned to obtain a three-layer structure; The cleaned three-layer structure is placed in an atomic layer deposition device, and an amorphous Al2O3 layer is prepared on the surface of the α-Al2O3 layer using an atomic layer deposition (ALD) process. CeO2 / HfO2 heterojunction layers were prepared on the surface of amorphous Al2O3 layer by magnetron sputtering.

5. The method for preparing a multi-layer insulation structure for high-temperature thin-film sensors according to claim 4, characterized in that: The pretreatment method of the metal substrate is as follows: first, the surface of the substrate is ground and polished, then it is immersed in acetone, anhydrous ethanol and deionized water in sequence for ultrasonic cleaning, and finally it is blown dry with nitrogen and dried on a heating table for use.

6. The method for preparing a multi-layer insulation structure for high-temperature thin-film sensors according to claim 4, characterized in that: The method for generating the α-Al2O3 layer is: The metal substrate with the NiCrAlY transition layer deposited thereon is placed in a tube furnace; Heat the furnace to 950-1050℃, evacuate and keep warm for 4-6 hours to precipitate the metallic aluminum; After cooling to 850-950℃, oxygen is introduced to oxidize the precipitated aluminum. The oxygen purity is not less than 99.995% and the oxidation time is 5-12 hours. The α-Al2O3 layer is obtained by cooling the furnace to room temperature; Among them, the aluminum precipitation oxidation process is 8×10 -4 The oxidation process is completed under a vacuum environment of Pa, and the oxygen pressure in the oxidation process is 100Pa.

7. The method for preparing a multi-layer insulation structure for a high-temperature thin-film sensor according to claim 6, characterized in that: The method for cleaning the metal substrate covered with the NiCrAlY transition layer and the α-Al2O3 layer is to immerse it in acetone, anhydrous ethanol and deionized water in sequence for ultrasonic cleaning, blow it dry with nitrogen, and dry it on a heating table for later use.

8. The method for preparing a multi-layer insulation structure for high-temperature thin-film sensors according to claim 7, characterized in that: The amorphous Al2O3 layer is prepared using trimethylaluminum (TMA) and oxygen plasma as precursors and water as an oxidant in a trimethylaluminum (TMA) nitrogen cleaning-oxygen plasma nitrogen cleaning cycle; each cycle lasts 12 seconds and the deposition temperature is 300-500°C.

9. The method for preparing a multi-layer insulation structure for a high-temperature thin-film sensor according to claim 8, characterized in that: In the preparation of the CeO2 / HfO2 heterogeneous stack, CeO2 is prepared by reactive DC magnetron sputtering, with an Ar / O2 ratio of 15:5-15:10 and a gas pressure of 0.3-0.6 Pa to improve its density.

10. A multi-layer insulation structure for high-temperature thin film sensors according to any one of claims 1 to 3, applied to thin film sensors for monitoring temperature and strain parameters of hot end components of aerospace equipment, characterized in that: The insulation resistance of the multi-layer insulation structure at 1000° C. is not less than 100 kΩ.

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