High-temperature-resistant film composite sensor and preparation method thereof

Abstract

The invention discloses a high-temperature-resistant film composite sensor and a preparation method thereof. The sensor comprises a YSZ coating, an Al2O3 layer, a SiO2 layer, a functional layer and a composite protection layer which are sequentially arranged on the surface of a metal substrate from bottom to top. The preparation method comprises the following steps: spraying the metal substrate, spraying the YSZ coating, polishing, preparing the Al2O3 layer, carrying out heat treatment, preparing the SiO2 layer and the composite protective layer, and carrying out heat treatment on the composite protective layer. The high-temperature-resistant film composite sensor can stably work for 48 hours under the ultrahigh-temperature condition of 1500 DEG C under the combined action of the films, has the advantages of being high in detection precision, long in service life and the like, and can be used for measuring working parameters of engine blades at high working temperature and high rotating speed at the same time. Meanwhile, the preparation method has the advantages of being simple in process, convenient to operate, low in preparation cost, high in yield and the like, is suitable for large-scale preparation and facilitates industrial application.

Description

Technical Field

[0001] The invention belongs to the technical field of thin film sensors and relates to a high temperature resistant thin film composite sensor and a preparation method thereof. Background Art

[0002] Thin film sensors have important applications in monitoring the process parameters of engine blades (such as temperature, strain, and heat flow, etc.). However, the maximum operating temperature of existing high-temperature thin film sensors is generally around 1000°C, and the maximum value is 1200°C, which is difficult to meet the monitoring needs of aircraft engines. To this end, the inventors of this application have proposed a high-temperature resistant thin film sensor that integrates temperature, strain, and heat flow testing functions. It can work for a long time at 1200°C, but it is still difficult to work for a long time at 1500°C. In particular, with the further improvement of the power-to-weight ratio of aircraft engines, the maximum temperature of its engine blades may be greater than 1200°C, and even reach 1500°C in some areas. Therefore, in order to meet the requirements of engine modification design and performance improvement, it is also necessary to develop a high-temperature resistant thin film sensor with a maximum operating temperature of 1500°C and can work for a long time at 1500°C. In addition, in the method of preparing thin film sensors, high temperature glue is often used to stick the functional layer to the engine blade. On the one hand, since the stuck sensor protrudes from the blade surface, it will interfere with the heat flow and temperature field around the blade, causing inaccurate measurement values. On the other hand, the sensor stuck to the engine blade has the defect of loose sticking, which easily causes the sensor to fall off the blade, and the fallen sensor has the risk of damaging the turbine system. Therefore, obtaining a high temperature resistant thin film composite sensor that can work for a long time under ultra-high temperature conditions of 1500℃ and a matching preparation method with simple process and convenient operation is of great significance for promoting the wide application of thin film sensors in the process parameter monitoring of aircraft engine blades. Summary of the invention

[0003] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art, provide a high temperature resistant thin film composite sensor that can work for a long time under ultra-high temperature conditions of 1500°C, and also provide a preparation method of the high temperature resistant thin film composite sensor with simple process and convenient operation.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0005] A high temperature resistant thin film composite sensor comprises a metal substrate, wherein a YSZ coating, an Al2O3 layer and a SiO2 layer are sequentially arranged on the surface of the metal substrate from bottom to top; a functional layer is arranged on the SiO2 layer; the functional layer is also covered with a composite protective layer; the composite protective layer is a mixed film of YSZ and Al2O3.

[0006] The above-mentioned high temperature resistant thin film composite sensor is further improved in that the thickness of the YSZ coating is 2000 μm to 3000 μm; and the YSZ coating is yttria-stabilized zirconia.

[0007] The above-mentioned high temperature resistant thin film composite sensor is further improved in that the thickness of the composite protective layer is 5 μm to 8 μm.

[0008] The above-mentioned high temperature resistant thin film composite sensor is further improved in that the metal substrate is an engine blade.

[0009] The above-mentioned high temperature resistant thin film composite sensor is further improved in that the Al2O3 layer is an Al2O3 thin film; the thickness of the Al2O3 layer is 3μm to 7μm.

[0010] The above-mentioned high temperature resistant thin film composite sensor is further improved in that the SiO2 layer is a SiO2 thin film; the thickness of the SiO2 layer is 2 μm to 4 μm.

[0011] The above-mentioned high-temperature resistant thin film composite sensor is further improved, wherein the functional layer includes a strain sensitive grid and a thin film thermocouple; the material of the strain sensitive grid is PdCr alloy; the thickness of the strain sensitive grid is 800nm~1200nm; the thin film thermocouple is a K-type thin film thermocouple, including a positive electrode film and a negative electrode film; the positive electrode film is a NiCr film; the thickness of the positive electrode film is 800nm~1200nm; the negative electrode film is a NiSi film; the thickness of the negative electrode film is 800nm~1200nm.

[0012] The above-mentioned high temperature resistant thin film composite sensor is further improved in that the strain sensitive grid and the thin film thermocouple are both connected with electrodes; the electrodes are Pt electrodes; and the thickness of the electrodes is 2 μm to 3 μm.

[0013] The above-mentioned high temperature resistant thin film composite sensor is further improved in that the electrode is also connected to a lead pad.

[0014] As a general technical concept, the present invention also provides a method for preparing a high temperature resistant thin film composite sensor, comprising the following steps:

[0015] S1. Sandblasting and cleaning the metal substrate;

[0016] S2, spraying YSZ coating on the surface of metal substrate;

[0017] S3, polishing the YSZ coating;

[0018] S4, preparing an Al2O3 layer on the surface of the YSZ coating after polishing;

[0019] S5, heat treating the Al2O3 layer;

[0020] S6, preparing a SiO2 layer on the surface of the heat-treated Al2O3 layer;

[0021] S7, preparing a functional layer on the SiO2 layer;

[0022] S8, preparing a composite protective layer on the functional layer; the composite protective layer is a mixed film of YSZ and Al2O3;

[0023] S9. Perform heat treatment on the composite protective layer to complete the preparation of the high temperature resistant thin film composite sensor.

[0024] The above preparation method is further improved, in step S1, the sandblasting time is 15min to 22min; the cleaning is: first, the metal substrate after sandblasting is placed in acetone for ultrasonic cleaning for 10min to 15min, then placed in alcohol for ultrasonic cleaning for 15min to 20min, and finally placed in deionized water for ultrasonic cleaning for 15min to 20min; after the cleaning is completed, the cleaned metal substrate is dried at 80°C to 100°C, and the drying time is 20min to 30min.

[0025] The above preparation method is further improved. In step S2, a YSZ coating is sprayed on the surface of the metal substrate by flame spraying. The process parameters of the flame spraying method are: a preheating temperature of 350°C to 750°C, a spraying distance of 8mm to 12mm, and an acetylene pressure of 0.02MPa to 0.04MPa.

[0026] The above preparation method is further improved, in step S3, the YSZ coating is polished by using an ion beam; the process parameters of the polishing process are: the background vacuum is less than 3×10 -4 Pa, the plate voltage is 300V, the current is 30mA~40mA, and the time is 0.5h~1h.

[0027] The above preparation method is further improved. In step S7, when the functional layer is a strain sensitive grid and a thin film thermocouple, the preparation method of the functional layer comprises the following steps:

[0028] S71. Prepare a thin film thermocouple on the SiO2 layer by dual ion beam sputtering. When the thin film thermocouple is a positive electrode thin film, the process parameters of the dual ion beam sputtering coating method are: using a 90% Ni-10% Cr target material with a purity of 99.99% as a target material, a voltage of 450V to 550V, and a current of 40mA to 60mA. When the thin film thermocouple is a negative electrode thin film, the process parameters of the dual ion beam sputtering coating method are: using a 97% Ni-3% Si target material with a purity of 99.99% as a target material, a voltage of 450V to 550V, and a current of 50mA to 55mA.

[0029] S72. Prepare a strain sensitive gate on the SiO2 layer by using a dual ion beam sputtering method. In the preparation process of the strain sensitive gate, the process parameters of the dual ion beam sputtering coating method are as follows: using 87% Pd-13% Cr target material with a purity of 99.99% as the target material, the voltage is 480V~560V, and the current is 50mA~55mA.

[0030] The above preparation method is further improved. In step S4, an Al2O3 layer is prepared on the surface of the polished YSZ coating by an ion beam sputtering coating method. The process parameters of the ion beam sputtering coating method are: an Al2O3 target material with a purity of 99.99% is used as the target material, and the vacuum degree is less than 1×10 -5 Pa, sputtering power is 100W~200W, Ar2 flow rate is 10sccm~30sccm, and coating time is 6h~10h.

[0031] The above preparation method is further improved, in step S5, the heat treatment process also includes introducing oxygen, the oxygen introduction amount is 4sccm~8sccm; the heat treatment temperature is 500℃~600℃; the heat treatment time is 3h~5h.

[0032] The above preparation method is further improved, in step S6, an ion beam sputtering coating method is used to prepare a SiO2 layer on the surface of the heat-treated Al2O3 layer; the process parameters of the ion beam sputtering coating method are: using a SiO2 target material with a purity of 99.99% as the target material, and a vacuum degree of less than 2.5×10 -4 Pa, the voltage is 450V~480V, the current is 35mA~55mA, and the sputtering process also includes the introduction of oxygen, and the flow rate of oxygen is 5sccm~7sccm.

[0033] The above-mentioned preparation method is further improved, and step S7 also includes: using ion beam sputtering coating method to prepare an electrode on the SiO2 layer, so that the electrode is connected to the functional layer; when the electrode is a Pt electrode, the process parameters of the ion beam sputtering coating method used are: using a Pt target material with a purity of 99.99% as the target material, a voltage of 500V~550V, and a current of 40mA~60mA.

[0034] The above-mentioned preparation method is further improved. In step S8, a dual-target co-sputtering method is used to prepare a mixed film of YSZ and Al2O3 on the functional layer; the process parameters of the dual-target co-sputtering method are as follows: a YSZ target material with a purity of 99.99% is used as the first target material, the sputtering power corresponding to the first target material is 150W~180W, and the Ar2 flow rate corresponding to the first target material is 20sccm~30sccm; a SiO2 target material with a purity of 99.99% is used as the second target material, the sputtering power corresponding to the second target material is 200W~250W, and the Ar2 flow rate corresponding to the second target material is 18sccm~22sccm, the gas pressure is 0.4Pa~0.6Pa, and the sputtering process also includes the introduction of oxygen, and the oxygen flow rate is 8sccm~12sccm.

[0035] The above preparation method is further improved, in step S9, the temperature of the heat treatment is 900°C to 1000°C; the time of the heat treatment is 1h to 2h.

[0036] The above-mentioned preparation method is further improved, wherein the high-temperature resistant thin film composite sensor includes a metal substrate, and the surface of the metal substrate is provided with a YSZ coating, an Al2O3 layer and a SiO2 layer from bottom to top in sequence; a functional layer is provided on the SiO2 layer; the functional layer is also covered with a composite protective layer; the composite protective layer is a mixed thin film of YSZ and Al2O3.

[0037] The above-mentioned preparation method is further improved in that the metal substrate is an engine blade.

[0038] The above preparation method is further improved in that the thickness of the YSZ coating is 2000 μm to 3000 μm; and the YSZ coating is yttria-stabilized zirconia.

[0039] The above preparation method is further improved, wherein the Al2O3 layer is an Al2O3 film; the thickness of the Al2O3 layer is 3μm to 7μm.

[0040] The above preparation method is further improved in that the SiO2 layer is a SiO2 film; the thickness of the SiO2 layer is 2μm to 4μm.

[0041] The above preparation method is further improved, wherein the functional layer includes a strain sensitive grid and a thin film thermocouple; the material of the strain sensitive grid is PdCr alloy; the thickness of the strain sensitive grid is 800nm~1200nm; the thin film thermocouple is a K-type thin film thermocouple, including a positive electrode thin film and a negative electrode thin film; the positive electrode thin film is a NiCr thin film; the thickness of the positive electrode thin film is 800nm~1200nm; the negative electrode thin film is a NiSi thin film; the thickness of the negative electrode thin film is 800nm~1200nm.

[0042] The above preparation method is further improved in that the strain sensitive grid and the thin film thermocouple are both connected with electrodes; the electrodes are Pt electrodes; and the thickness of the electrodes is 2 μm to 3 μm.

[0043] The above preparation method is further improved in that the electrode is also connected to a lead pad.

[0044] The above preparation method is further improved in that the thickness of the composite protective layer is 5 μm to 8 μm.

[0045] Compared with the prior art, the advantages of the present invention are:

[0046] (1) In view of the shortcomings of existing thin film sensors, such as poor structural stability and insulation performance of the insulating layer under ultra-high temperature conditions of 1500°C, poor high temperature oxidation resistance of the protective layer under 1500°C, and the resulting defects that the sensors are difficult to work for a long time under ultra-high temperature conditions of 1500°C, the present invention creatively provides a high temperature resistant thin film composite sensor, wherein a YSZ coating, an Al2O3 layer, a SiO2 layer, a functional layer and a composite protective layer are sequentially arranged on the surface of a metal substrate from bottom to top, wherein the composite protective layer is a mixed thin film of YSZ and Al2O3. In the present invention, a YSZ coating is arranged between the metal substrate and the functional layer. The YSZ coating is used as an insulating layer, which can significantly improve the high-temperature insulation resistance of the sensor, wherein the insulation resistance is 1MΩ at 1200°C and 50KΩ at 1500°C. At this time, the sensor can work stably at 1500°C. At the same time, an Al2O3 layer and a SiO2 layer are arranged between the YSZ coating and the functional layer. Since they have very good compactness, adhesion and high-temperature insulation, the high-temperature insulation resistance of the sensor is further improved. At the same time, the adhesion of the functional layer can also be improved, and the functional layer can be prevented from falling off due to excessive difference in thermal expansion coefficient. On this basis, a mixed film of YSZ and Al2O3 is arranged on the surface of the functional layer. Since the mixed film of YSZ and Al2O3 has very excellent high-temperature resistance, it can be used as a protective layer to effectively prevent the functional layer from being oxidized and damaged, thereby achieving effective protection of the functional layer, which is conducive to ensuring that the sensor can work for a long time under high-temperature conditions of 1500°C. The high temperature resistant thin film composite sensor of the present invention can significantly improve the stability and high temperature insulation of the sensor under ultra-high temperature conditions of 1500°C under the joint action of the YSZ coating, the Al2O3 layer, the SiO2 layer, and the mixed film of YSZ and Al2O3. Therefore, the sensor can work for a long time under ultra-high temperature conditions of 1500°C, wherein the stable working time under the ultra-high temperature conditions of 1500°C is as long as 48 hours, while the working time of conventional thin film sensors under ultra-high temperature conditions of 1500°C is generally within 2 hours.

[0047] (2) The high temperature resistant thin film composite sensor of the present invention comprises a strain sensitive grid and a thin film thermocouple, which can be used to simultaneously measure the working parameters (such as temperature, strain, etc.) of the engine blades at high working temperature and high speed. At the same time, by measuring the real-time temperature data and combining the resistance temperature coefficient of the strain sensitive grid, the influence of temperature on the resistance value of the strain resistor can be eliminated, and then the strain resistor value can be compensated, thereby greatly improving the measurement accuracy of the sensor, with high use value and good application prospects.

[0048] (3) In view of the shortcomings of the existing thin film sensors, such as the poor structural stability and insulation performance of the insulating layer under ultra-high temperature conditions of 1500°C, the poor high temperature oxidation resistance of the protective layer at 1500°C, and the protrusion of the protective layer on the surface of the engine blade, and the resulting defects that the sensor is difficult to work for a long time under ultra-high temperature conditions of 1500°C, has poor detection accuracy, and a short service life, the present invention also provides a method for preparing a high temperature resistant thin film composite sensor, wherein the metal substrate is first sandblasted, which not only can quickly form pits on the surface of the metal substrate, which is conducive to preparing a sensor with the same surface as the metal substrate, but also can form a rough surface on the surface of the metal substrate, which is conducive to firmly fixing the YSZ coating on the surface of the metal substrate. Further, by polishing the YSZ coating, the adhesion of the YSZ coating can be greatly improved, so that the Al2O3 layer can be firmly fixed on the surface of the YSZ coating. At the same time, by heat treating the Al2O3 layer, the Al2O3 layer can be eliminated. The defects in the Al2O3 layer make it more compact, which is beneficial to improve the stability of the sensor under high temperature conditions. In addition, the SiO2 layer is prepared on the surface of the Al2O3 layer after heat treatment, which can further improve the high temperature insulation performance of the sensor. Furthermore, the functional layer is prepared on the SiO2 layer, and the functional layer can be firmly fixed on the surface of the metal substrate. Finally, a mixed film of YSZ and Al2O3 is prepared on the functional layer, and the mixed film of YSZ and Al2O3 is heat-treated, and a protective layer with strong high temperature resistance can be formed on the surface of the functional layer, so that the functional layer can be effectively prevented from being oxidized and damaged under ultra-high temperature conditions. Finally, a high-temperature resistant thin film composite sensor with high detection accuracy, long service life, and long-term operation under ultra-high temperature conditions of 1500°C is prepared, which can be used to simultaneously measure the working parameters (such as temperature, strain, etc.) of the engine blades at high working temperature and high speed. It is a new type of multifunctional thin film sensor with excellent detection performance and can be widely used. At the same time, the preparation method of the present invention has the advantages of simple process, convenient operation, low preparation cost, high yield rate, etc., is suitable for large-scale preparation, and is conducive to industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to make the purpose, technical solution and advantages of the embodiments of the present invention more clear, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0050] Figure 1 This is a schematic diagram of the cross-sectional structure of the high temperature resistant thin film composite sensor in Example 1 of the present invention.

[0051] Figure 2 Schematic diagram of the top view of the high temperature resistant thin film composite sensor in Example 1 of the present invention.

[0052] Figure 3This is a process flow chart for preparing the high temperature resistant thin film composite sensor in Example 1 of the present invention.

[0053] Legend:

[0054] 1. Metal substrate; 2. YSZ coating; 3. Al2O3 layer; 4. SiO2 layer; 5. Functional layer; 51. Strain sensitive grid; 52. Thin film thermocouple; 6. Composite protective layer; 7. Lead pad. DETAILED DESCRIPTION

[0055] The present invention is further described below in conjunction with the accompanying drawings and specific preferred embodiments, but the protection scope of the present invention is not limited thereby.

[0056] Embodiment 1:

[0057] like Figure 1 and Figure 2 As shown, a high temperature resistant thin film composite sensor comprises a metal substrate 1, on the surface of which a YSZ coating 2, an Al2O3 layer 3 and a SiO2 layer 4 are arranged in sequence from bottom to top, a functional layer 5 is arranged on the SiO2 layer 4, and the functional layer 5 is also covered with a composite protective layer 6, which is a mixed film of YSZ and Al2O3.

[0058] In this embodiment, the thickness of the YSZ coating 2 is 2500 μm, and the YSZ coating 2 is yttria-stabilized zirconia.

[0059] In this embodiment, the thickness of the composite protective layer 5 is 8 μm.

[0060] In this embodiment, the metal substrate 1 is an engine blade.

[0061] In this embodiment, the Al2O3 layer 3 is an Al2O3 film with a thickness of 4 μm.

[0062] In this embodiment, the SiO2 layer 4 is a SiO2 thin film with a thickness of 4 μm.

[0063] In this embodiment, the functional layer 5 includes a strain sensitive grid 51 and a thin film thermocouple 52 .

[0064] In this embodiment, the material of the strain sensitive gate 51 is PdCr alloy, and the thickness of the strain sensitive gate 51 is 1000 nm.

[0065] In this embodiment, the thin film thermocouple 52 is a K-type thin film thermocouple, including a positive electrode thin film and a negative electrode thin film, wherein the positive electrode thin film is a NiCr thin film with a thickness of 1200 nm; and the negative electrode thin film is a NiSi thin film with a thickness of 1200 nm.

[0066] In this embodiment, electrodes are connected to the strain sensitive grid 51 and the thin film thermocouple 52 . The electrodes are Pt electrodes, and the thickness of the electrodes is 3 μm.

[0067] In this embodiment, a lead pad 7 is also connected to the electrode.

[0068] A method for preparing the high temperature resistant thin film composite sensor in the present embodiment, the preparation process flow chart is as follows Figure 3 As shown, the following steps are included:

[0069] S1. Sandblast and clean the metal substrate, specifically:

[0070] S11. Sandblasting of substrate material: Place the engine blade (metal substrate) in a sandblasting apparatus and perform sandblasting on the area where the sensor is to be set for 20 minutes.

[0071] S12. Cleaning: The sandblasted engine blades are ultrasonically cleaned in acetone for 15 minutes, then in alcohol for 15 minutes, and finally in deionized water for 15 minutes. After cleaning, the cleaned metal substrate is dried at 100° C. for 20 minutes.

[0072] S2. Flame spraying YSZ coating: The flame spraying method is used to spray the YSZ coating on the surface of the metal substrate. Specifically, the engine blade is placed in a spraying fixture, and the YSZ coating is flame sprayed by acetylene pressurization. A layer of YSZ coating is evenly sprayed on the polished surface of the engine blade to play a transition and high-temperature insulation role. The thickness is controlled at 2500μm. The process parameters of the flame spraying method are: preheating temperature is 360℃, spraying distance is 10mm, and acetylene pressure is 0.03MPa.

[0073] S3. Ion beam polishing of coating surface: The YSZ coating is polished by ion beam. Specifically, the blade sprayed with YSZ coating is placed in an ion beam coating machine, and the YSZ coating surface is polished by parallel ion beam to improve the surface roughness and enhance the adhesion of the film. The process parameters of the polishing treatment are: the background vacuum is less than 3×10 -4 Pa, the plate voltage is 300V, the current is 40mA, and the time is 1h.

[0074] S4. Preparation of aluminum oxide film: The Al2O3 layer was prepared on the surface of the polished YSZ coating by ion beam sputtering. Specifically, the sample was sent to the process chamber by a conveyor belt, and the mechanical pump and cold pump were turned on to evacuate the sample until the vacuum degree was less than 1×10 -5After Pa, an Al2O3 target with a purity of 99.99% was used as the target material, and the RF source parameters were set as follows: sputtering power was 160W, Ar2 flow rate was 25sccm, the RF power was turned on, and coating began. The coating time was 8h, and the thickness of the alumina film was controlled to be 4μm.

[0075] S5. Heat treatment of aluminum oxide film: Heat treatment is performed on the Al2O3 layer. Specifically, the blade coated with aluminum oxide film is placed in a high-temperature tube furnace for oxidation heat treatment. The heat treatment temperature is 600°C and the heat treatment time is 6 hours. Oxygen is passed during the heat treatment process and the oxygen flow rate is controlled at 6 sccm.

[0076] S6. Preparation of SiO2 thin film: The SiO2 layer is prepared on the surface of the heat-treated Al2O3 layer by ion beam sputtering coating method. Specifically, the heat-treated blade is placed in an ion beam coating machine to prepare the SiO2 layer on the surface of the heat-treated Al2O3 layer. The process parameters of the ion beam sputtering coating method are: a SiO2 target material with a purity of 99.99% is used as the target material, and the vacuum degree is less than 2.5×10 -4 Pa, the voltage is 460 V, the current is 50 mA, and the sputtering process also includes the introduction of oxygen with a flow rate of 6 sccm.

[0077] S7, preparing a functional layer on the SiO2 layer, specifically preparing a thin film thermocouple and a strain sensitive grid on the SiO2 layer, comprising the following steps:

[0078] S71. Preparation of thin film thermocouples: Prepare thin film thermocouples on the SiO2 layer by dual ion beam sputtering. Specifically, place the blade in an ion beam coating machine, and prepare a K-type thin film thermocouple at the corresponding position of the SiO2 film under the action of a stainless steel mask, including a positive electrode film and a negative electrode film. When the thin film thermocouple is a positive electrode film, the process parameters of the dual ion beam sputtering coating method are: using a 90% Ni-10% Cr target material with a purity of 99.99% as the target material, a voltage of 550V, and a current of 60mA; when the thin film thermocouple is a negative electrode film, the process parameters of the dual ion beam sputtering coating method are: using a 97% Ni-3% Si target material with a purity of 99.99% as the target material, a voltage of 550V, and a current of 55mA.

[0079] S72. Preparation of PdCr strain sensitive pattern: A strain sensitive grid is prepared on the SiO2 layer by using a dual ion beam sputtering method. Specifically, a blade is placed in an ion beam coating machine, and a strain sensitive grid is prepared on the corresponding position of the SiO2 film under the action of a stainless steel mask. During the preparation of the strain sensitive grid, the process parameters of the dual ion beam sputtering coating method are as follows: 87% Pd-13% Cr target material with a purity of 99.99% is used as the target material, the voltage is 480V, and the current is 50mA.

[0080] Step S7 also includes the preparation of electrodes: preparing electrodes on the SiO2 layer by ion beam sputtering coating method, specifically preparing Pt electrodes at the electrode positions of the PrCr strain grid and the thin film thermocouple, connecting the Pt electrode with the PrCr strain grid and the thin film thermocouple to form a functional layer, wherein the process parameters of the ion beam sputtering coating method used are: using a Pt target material with a purity of 99.99% as the target material, a voltage of 500V, and a current of 40mA.

[0081] S8. Preparation of protective layer: A composite protective layer is prepared on the functional layer by using a dual-target co-sputtering method. Specifically, the blade is placed in an ion beam coating machine, and the mechanical pump and cold pump are turned on to evacuate the blade to a vacuum degree of less than 1×10 -5 Pa, start coating, and turn on the first RF (first target) and the second RF (second target) power supplies at the same time to prepare a mixed film of YSZ and Al2O3 on all functional layers except the electrode, wherein the process parameters of the first RF are: YSZ target with a purity of 99.99% as the first target, sputtering power of 160W, and Ar2 flow rate of 25sccm; the process parameters of the second RF are: SiO2 target with a purity of 99.99% as the second target, sputtering power of 200W, and Ar2 flow rate of 22sccm; during the sputtering process, adjust the opening of the cold pump to ensure that the gas pressure during the sputtering process is 0.4Pa, and the sputtering process also includes the introduction of oxygen, and the oxygen flow rate is 10sccm.

[0082] S9. Overall heat treatment of the sensor: The composite protective layer is heat treated by placing the blade in an air environment at 1000°C and annealing for 1 hour at normal pressure. After cooling to room temperature, the sample is taken out to obtain a high temperature resistant thin film composite sensor.

[0083] After testing, the high temperature resistant film composite sensor prepared in Example 1 of the present invention can work stably for up to 48 hours under ultra-high temperature conditions of 1500°C, while the existing conventional high temperature resistant film sensor (the high temperature resistant insulating layer used in the sensor is composed of Al2O3 layer, Ta2O5 layer and SiO2 layer, and the protective layer is YSZ coating) generally works within 2 hours under ultra-high temperature conditions of 1500°C, which shows that the high temperature resistant film composite sensor of the present invention has more excellent high temperature resistance and stability, and can work for a long time under ultra-high temperature conditions of 1500°C. At the same time, the strain measurement accuracy of the high temperature resistant film composite sensor prepared in this embodiment can reach 5% FS.

[0084] From the above results, it can be seen that the high temperature resistant thin film composite sensor of the present invention has the advantages of high detection accuracy, long service life, and long working time under ultra-high temperature conditions of 1500°C. It can be used to simultaneously measure the working parameters (such as temperature, strain, etc.) of engine blades at high working temperature and high speed. It is a new type of multifunctional thin film sensor with excellent detection performance and can be widely used. At the same time, the preparation method of the present invention has the advantages of simple process, convenient operation, low preparation cost, high yield rate, etc., which is suitable for large-scale preparation and conducive to industrial application.

[0085] The above embodiments are only preferred implementations of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A high temperature resistant thin film composite sensor, characterized in that: It comprises a metal substrate, on the surface of which a YSZ coating, an Al2O3 layer and a SiO2 layer are arranged in sequence from bottom to top; a functional layer is arranged on the SiO2 layer; the functional layer is also covered with a composite protective layer; the composite protective layer is a mixed film of YSZ and Al2O3.

2. The high temperature resistant thin film composite sensor according to claim 1, characterized in that: The thickness of the YSZ coating is 2000 μm to 3000 μm; the YSZ coating is yttria-stabilized zirconia.

3. The high temperature resistant thin film composite sensor according to claim 1, characterized in that: The thickness of the composite protective layer is 5 μm to 8 μm.

4. The high temperature resistant thin film composite sensor according to any one of claims 1 to 3, characterized in that: The metal substrate is an engine blade; The Al2O3 layer is an Al2O3 thin film; the thickness of the Al2O3 layer is 3 μm to 7 μm; The SiO2 layer is a SiO2 thin film; the thickness of the SiO2 layer is 2 μm to 4 μm; The functional layer includes a strain sensitive grid and a thin film thermocouple; the material of the strain sensitive grid is PdCr alloy; the thickness of the strain sensitive grid is 800nm-1200nm; the thin film thermocouple is a K-type thin film thermocouple, including a positive electrode thin film and a negative electrode thin film; the positive electrode thin film is a NiCr thin film; the thickness of the positive electrode thin film is 800nm-1200nm; the negative electrode thin film is a NiSi thin film; the thickness of the negative electrode thin film is 800nm-1200nm; The strain sensitive grid and the thin film thermocouple are both connected with electrodes; the electrodes are Pt electrodes; the thickness of the electrodes is 2 μm to 3 μm; The electrode is also connected with a lead pad.

5. A method for preparing a high temperature resistant thin film composite sensor, characterized in that: The following steps are involved: S1. Sandblasting and cleaning the metal substrate; S2, spraying YSZ coating on the surface of metal substrate; S3, polishing the YSZ coating; S4, preparing an Al2O3 layer on the surface of the YSZ coating after polishing; S5, heat treating the Al2O3 layer; S6, preparing a SiO2 layer on the surface of the heat-treated Al2O3 layer; S7, preparing a functional layer on the SiO2 layer; S8, preparing a composite protective layer on the functional layer; the composite protective layer is a mixed film of YSZ and Al2O3; S9. Perform heat treatment on the composite protective layer to complete the preparation of the high temperature resistant thin film composite sensor.

6. The preparation method according to claim 5, characterized in that: In step S1, the sandblasting time is 15 minutes to 22 minutes; the cleaning is: firstly, the metal substrate after sandblasting is ultrasonically cleaned in acetone for 10 minutes to 15 minutes, then placed in alcohol for ultrasonic cleaning for 15 minutes to 20 minutes, and finally placed in deionized water for ultrasonic cleaning for 15 minutes to 20 minutes; after the cleaning is completed, the cleaned metal substrate is dried at 80° C. to 100° C., and the drying time is 20 minutes to 30 minutes; In step S2, a YSZ coating is sprayed on the surface of the metal substrate by flame spraying; the process parameters of the flame spraying method are: a preheating temperature of 350° C. to 750° C., a spraying distance of 8 mm to 12 mm, and an acetylene pressure of 0.02 MPa to 0.04 MPa; In step S3, the YSZ coating is polished by using an ion beam. The process parameters of the polishing process are: the background vacuum is less than 3×10 -4 Pa, the plate voltage is 300V, the current is 30mA~40mA, and the time is 0.5h~1h.

7. The preparation method according to claim 6, characterized in that: In step S7, when the functional layer is a strain sensitive grid and a thin film thermocouple, the method for preparing the functional layer comprises the following steps: S71. Prepare a thin film thermocouple on the SiO2 layer by using a dual ion beam sputtering method; when the thin film thermocouple is a positive electrode thin film, the process parameters of the dual ion beam sputtering coating method are: using a 90% Ni-10% Cr target material with a purity of 99.99% as a target material, a voltage of 450V to 550V, and a current of 40mA to 60mA; when the thin film thermocouple is a negative electrode thin film, the process parameters of the dual ion beam sputtering coating method are: using a 97% Ni-3% Si target material with a purity of 99.99% as a target material, a voltage of 450V to 550V, and a current of 50mA to 55mA; S72. Prepare a strain sensitive gate on the SiO2 layer by using a dual ion beam sputtering method. In the preparation process of the strain sensitive gate, the process parameters of the dual ion beam sputtering coating method are as follows: using 87% Pd-13% Cr target material with a purity of 99.99% as the target material, the voltage is 480V~560V, and the current is 50mA~55mA.

8. The preparation method according to any one of claims 5 to 7, characterized in that In step S4, an Al2O3 layer is prepared on the surface of the polished YSZ coating by an ion beam sputtering coating method; the process parameters of the ion beam sputtering coating method are: an Al2O3 target material with a purity of 99.99% is used as the target material, and the vacuum degree is less than 1×10 -5 Pa, sputtering power is 100W~200W, Ar2 flow rate is 10sccm~30sccm, and coating time is 6h~10h; In step S5, the heat treatment process further includes introducing oxygen, the amount of oxygen introduced is 4 sccm to 8 sccm; the heat treatment temperature is 500° C. to 600° C.; the heat treatment time is 3 h to 5 h; In step S6, an ion beam sputtering coating method is used to prepare a SiO2 layer on the surface of the heat-treated Al2O3 layer. The process parameters of the ion beam sputtering coating method are: a SiO2 target material with a purity of 99.99% is used as the target material, and a vacuum degree of less than 2.5×10 - 4 Pa, voltage is 450V~480V, current is 35mA~55mA, and oxygen is also introduced during the sputtering process, and the flow rate of oxygen is 5sccm~7sccm; Step S7 further includes: preparing an electrode on the SiO2 layer by an ion beam sputtering coating method, so that the electrode is connected to the functional layer; when the electrode is a Pt electrode, the process parameters of the ion beam sputtering coating method are: using a Pt target material with a purity of 99.99% as a target material, a voltage of 500V to 550V, and a current of 40mA to 60mA; In step S8, a dual-target co-sputtering method is used to prepare a mixed film of YSZ and Al2O3 on the functional layer; the process parameters of the dual-target co-sputtering method are: a YSZ target material with a purity of 99.99% is used as the first target material, the sputtering power corresponding to the first target material is 150W~180W, and the Ar2 flow rate corresponding to the first target material is 20sccm~30sccm; a SiO2 target material with a purity of 99.99% is used as the second target material, the sputtering power corresponding to the second target material is 200W~250W, and the Ar2 flow rate corresponding to the second target material is 18sccm~22sccm, the gas pressure is 0.4Pa~0.6Pa, and the sputtering process also includes the introduction of oxygen, and the oxygen flow rate is 8sccm~12sccm; In step S9, the temperature of the heat treatment is 900° C. to 1000° C.; the time of the heat treatment is 1 h to 2 h.

9. The preparation method according to claim 8, characterized in that: The high temperature resistant thin film composite sensor comprises a metal substrate, on the surface of which a YSZ coating, an Al2O3 layer and a SiO2 layer are arranged in sequence from bottom to top; a functional layer is arranged on the SiO2 layer; the functional layer is also covered with a composite protective layer; the composite protective layer is a mixed film of YSZ and Al2O3.

10. The preparation method according to claim 9, characterized in that: The metal substrate is an engine blade; The thickness of the YSZ coating is 2000 μm to 3000 μm; the YSZ coating is yttria-stabilized zirconia; The Al2O3 layer is an Al2O3 thin film; the thickness of the Al2O3 layer is 3 μm to 7 μm; The SiO2 layer is a SiO2 thin film; the thickness of the SiO2 layer is 2 μm to 4 μm; The functional layer includes a strain sensitive grid and a thin film thermocouple; the material of the strain sensitive grid is PdCr alloy; the thickness of the strain sensitive grid is 800nm-1200nm; the thin film thermocouple is a K-type thin film thermocouple, including a positive electrode thin film and a negative electrode thin film; the positive electrode thin film is a NiCr thin film; the thickness of the positive electrode thin film is 800nm-1200nm; the negative electrode thin film is a NiSi thin film; the thickness of the negative electrode thin film is 800nm-1200nm; The strain sensitive grid and the thin film thermocouple are both connected with electrodes; the electrodes are Pt electrodes; the thickness of the electrodes is 2 μm to 3 μm; The electrode is also connected to a lead pad; The thickness of the composite protective layer is 5 μm to 8 μm.

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