Preparation method of ceramic oxide film thermocouple for aero-engine temperature measurement

Abstract

The application relates to a preparation method of a ceramic oxide film thermocouple for temperature measurement of an aero-engine. Two thermoelectric arms of the film thermocouple are composed of an ITO:X film and an In2O3 film, wherein the ITO:X film is composed of three-layer ITO:C, ITO:C:N and ITO:C:N:Ni films from bottom to top, and the film is prepared by a magnetron sputtering method. The specific preparation method is as follows: the specific steps include the following: firstly, pretreating a workpiece; secondly, depositing the film on the pretreated workpiece by using a magnetron sputtering co-sputtering deposition process, depositing the In2O3 film of the thermoelectric arm first, then depositing the thermoelectric arm composed of three-layer different ITO:X films layer by layer; depositing the ITO:C film in the first layer, the thickness is not greater than 1 mu m; depositing the ITO:C:N film in the second layer, the thickness is not greater than 800 nm; depositing the ITO:C:N:Ni film in the third layer, the thickness is not greater than 600 nm; and the three-layer films all present crystal face (222) preferred growth. The ITO:X / In2O3 film thermocouple prepared by the method can effectively improve the thermoelectric performance and high-temperature stability of the film thermocouple, and then realizes accurate measurement of the transient temperature of the film thermocouple on the surface of a high-temperature component.

Description

TECHNICAL FIELD

[0001] The present application relates to surface temperature testing technology, and relates to selecting ceramic oxide X-ITO film as a thermoelectric arm and contacting the oxide In2O3 film to form a thin film thermocouple. The X-ITO film constituting the thin film thermocouple is realized high-temperature structural stability and interface stability through composition regulation and laminated structure, multi-target co-sputtering, and the high-temperature stability, thermoelectric performance and substrate bonding force of the X-ITO / In2O3 thin film thermocouple under high-temperature conditions are improved through special composition design and microstructure regulation of the multi-layer structure. The specific steps include: first, pretreating the workpiece, and then depositing the thin film on the pretreated workpiece through a magnetron sputtering co-sputtering deposition process, depositing the In2O3 film of the thermoelectric arm first, and then depositing the thermoelectric arm composed of three different X-ITO films layer by layer; the first layer is deposited with the ITO:C film, the thickness is not greater than 1 μm; the second layer is deposited with the ITO:C:N film, the thickness is not greater than 800 nm; the third layer is deposited with the ITO:C:N:Ni film, the thickness is not greater than 600 nm; and the three layers of films all present crystal face (222) preferred growth. The X-ITO / In2O3 thin film thermocouple prepared through this method can effectively improve the thermoelectric performance and high-temperature stability of the thin film thermocouple, and further realize accurate measurement of the transient temperature of the surface of the high-temperature component. BACKGROUND

[0002] In the design and verification test of an aero-engine, the temperature and distribution of the surface of a turbine blade and the inner wall of a combustion chamber and the like need to be accurately measured, so as to accurately evaluate the cold efficiency design of the hot end component and the effect of the thermal barrier coating. At present, the turbine inlet temperature has exceeded 1600 DEG C, although some traditional armored thermocouples can meet such high temperature measurement, but they will damage the overall structure of the turbine blade or interfere with the airflow state in the combustion chamber. Compared with ordinary thermocouples, thin film thermocouples have the advantages of small heat capacity, fast response, high sensitivity and easy integration, and the thin film thermocouples can overcome these shortcomings. According to the different materials, the thin film thermocouples can be divided into metal alloy type, ceramic type and composite type. Since the metal material thin film thermocouple will appear oxidation failure and other problems in the harsh high-temperature environment, the ceramic material has the advantages of oxidation resistance and high temperature resistance, so that the ceramic thin film thermocouple has been favored by researchers in recent years. At present, the thin film thermocouple composed of ITO-based oxide ceramic has more advantages in high-temperature stability and thermoelectric potential output.

[0003] ITO film is a kind of heavy doped, high degenerate n-type oxide ceramic material, and a large number of related research work has been carried out at home and abroad, which improves the sensitivity, temperature measuring range, service life and other performances of thin film thermocouple discrete element, but there are still many challenges in practical application. The preparation of sensitive layer thin film with high temperature stability and high sensitivity, the thermal adaptation problem of multi-layer material system, and the uniform thin film deposition on complex curved surface still restrict the temperature measurement application of thin film thermocouple on high temperature parts of aero-engine. The carrier of ITO material itself is contributed by Sn element instead of In element and its own oxygen vacancy defects, which causes the instability of ITO thin film material at high temperature. Single doping can regulate the microstructure and carrier concentration, improve the stability and thermoelectric performance of the material, but it cannot completely solve the problem, and multi-element doping and double design of laminated can solve the high temperature stability and interface problem of ITO thin film based thermocouple. The multi-layer X-ITO thin film prepared by doping ITO thin film can improve the high temperature stability and thermoelectric performance of X-ITO / In2O3 thin film thermocouple, and realize the application of X-ITO / In2O3 thin film thermocouple under the condition of temperature below 1200 DEG C. SUMMARY

[0004] The purpose of the present application is to prepare a multi-layer X-ITO / In2O3 thin film thermocouple with special orientation, which can realize high temperature stability and excellent thermoelectric performance of thin film thermocouple at high temperature, and promote the application of thin film thermocouple in engine high temperature part temperature measurement.

[0005] The technical scheme of the present application is:

[0006] The present application provides a preparation method of ceramic oxide thin film thermocouple for temperature measurement of aero-engine, which comprises the following steps:

[0007] Step 1, pretreatment of test piece

[0008] When the test piece is a metal material, an insulating layer is deposited on the surface of the test piece by a magnetron sputtering process, and the thickness of the insulating layer is 1.5-2.5 microns; when the test piece is a ceramic material, the surface of the test piece is cleaned;

[0009] Step 2, preparation of In2O3 thin film thermocouple arm

[0010] A first mask is installed on the surface of the test piece, and an opening is formed on the mask, so that the opening shape is the In2O3 thermocouple arm area; In2O3 thin film is deposited in the opening by a magnetron sputtering process, and the thickness of the thin film is less than 2 microns;

[0011] The magnetron sputtering parameters are as follows: the initial vacuum pressure of the vacuum chamber is not more than 4.0x10 －4Pa, the sputtering gas pressure is 0.8Pa-1.5Pa after filling argon, the substrate heating temperature is 400-500℃, the sputtering target material is In2O3 target material, the direct current power is 80W-150W, and the metal workpiece is naturally cooled to room temperature after sputtering;

[0012] Step 3, X-ITO thin film thermoelectric arm preparation

[0013] The first mask is replaced by the second mask on the surface of the test piece, and an opening is formed on the second mask, so that the opening shape corresponds to the X-ITO thermoelectric arm area; X-ITO thin film is deposited in the opening by a magnetron sputtering process; ITO is indium tin oxide, and X represents a doping element; The magnetron sputtering process includes ITO target, carbon target and nickel target; The magnetron sputtering process is divided into three continuous stages;

[0014] The first stage magnetron sputtering parameters are: the sputtering target material is ITO target material and carbon target material working at the same time, the initial vacuum pressure of the vacuum chamber is not more than 5.0x10 －3 Pa, the sputtering gas pressure is 0.2Pa-0.6Pa after filling argon, the substrate heating temperature is 300-400℃, the ITO target material direct current power is 50-150W, and the carbon target material direct current power is 50W or less; The first stage deposition thickness is 1.0μm or less, and the target material is closed after reaching the thickness, and the temperature is controlled to reduce to 200-300℃;

[0015] The second stage magnetron sputtering parameters are: while filling argon, nitrogen is also introduced, and the flow rate ratio of nitrogen to argon is 1:1-1:15; After the introduction of nitrogen, the ITO target and the carbon target are turned on, the initial vacuum pressure of the vacuum chamber remains unchanged, the sputtering gas pressure remains unchanged, the substrate heating temperature remains at 200-300℃, the ITO target direct current power is 50-150W, and the carbon target direct current power is 50W or less; The second stage deposition thickness is 0.8μm or less, and the target material is closed after reaching the thickness, and the temperature is controlled to reduce to 100-200℃;

[0016] The third stage magnetron sputtering parameters are: the flow rates of argon and nitrogen remain unchanged; ITO target, carbon target and nickel target are turned on, the initial vacuum pressure of the vacuum chamber remains unchanged, the substrate heating temperature remains at 100-200℃, the ITO target direct current power is 50-150W, the carbon target direct current power is 50W or less, and the nickel target direct current power is 50W or less; The third stage deposition thickness is 0.6μm or less, and the magnetron sputtering process is ended after reaching the thickness, and the temperature is naturally cooled to room temperature.

[0017] Step 4, annealing treatment

[0018] The test piece is subjected to annealing treatment, and the annealing temperature is 550-700℃, and the annealing time is not less than 60min.

[0019] Further, the purity of the nitrogen is 99.999%.

[0020] Further, the flow rate of the nitrogen is not more than 18sccm.

[0021] Further, the purity of the ITO target material is 99.99%.

[0022] Further, the purity of the carbon target material is 99.999%.

[0023] Further, the purity of the nickel target material is 99.99%.

[0024] Further, the test piece is a turbine blade of a turbofan engine.

[0025] Further, the material of the test piece is a nickel-based high-temperature alloy.

[0026] The advantage of the present application is that: the aero-engine is the "heart" of the aircraft, and in the process of high-speed operation, it bears high temperature (> 1700℃), high pressure (> 50bar), high speed (> 20000r / min) and other harsh environments, and it is difficult to carry out high-precision real-time temperature monitoring. The thin film thermocouple has the advantages of non-destructive testing component structure, short response time, small influence on the test environment, heat shock resistance and anti-peeling, and becomes the first choice for real-time temperature monitoring of the aero-engine. When depositing the X-ITO / In2O3 thin film thermocouple on the metal workpiece, a transition layer, which is also an insulating layer, needs to be deposited; on the ceramic workpiece, the thin film thermocouple can be directly deposited. By adjusting the composition of the X-ITO thin film and designing the double-layer structure, the high-temperature stability and thermoelectric performance of the thin film thermocouple can be obviously improved. The thin film thermocouple is composed of multiple X-ITO films and In2O3 films. The multiple X-ITO films are ITO:C film, ITO:C:N film and ITO:C:N:Ni film from bottom to top, and the state is crystalline and grows along the crystal face (222). The X-ITO film with (222) preferred orientation has high carrier mobility and Sn ion doping rate. At the same time, the doping of X element can not only improve the concentration of carriers, but also adjust the microstructure of the ITO film to improve its high-temperature stability.

[0027] The outer layer ITO:C:N:Ni film is doped with three elements to maximize the stability of the X-ITO film, and has better mechanical properties and impact resistance. The inner layer ITO:C film is doped with fewer elements, which can improve the stability of the film and the binding property of the X-ITO film and the substrate. The middle layer ITO:C:N:Ni film is a transition layer. The thermal stability and chemical stability of the In2O3 film are relatively stable. The In2O3 film is sputtered by a radio frequency power source. The deposition of the X-ITO film after the deposition of the In2O3 film also protects the entire film thermocouple.

[0028] In summary, the X-ITO film and the In2O3 film with multi-element doping, different doping element stacking and preferred orientation design have excellent high-temperature stability, thermoelectric properties, interface properties and binding property with the substrate, and can realize precise real-time monitoring of temperature in the range of room temperature to 1200℃, which lays a foundation for real-time monitoring technology of high-temperature parts of an aero-engine. DETAILED DESCRIPTION

[0029] The disclosed examples will be described more fully. Indeed, many different examples can be described and it is to be understood that the examples described herein are by no means limiting, and that these examples are presented solely to provide a thorough description of the disclosure and to convey the scope of the disclosure to those skilled in the art.

[0030] Example 1:

[0031] Step 1: An aluminum oxide transition layer is deposited on the surface of a test piece or a metal piece by a magnetron sputtering deposition process, and the thickness is not more than 2.0 μm. The target material is selected to be 99.99% aluminum oxide target material, the chamber pressure is not more than 4.0 x 10 －4 Pa, the substrate heating temperature is 400℃, the sputtering pressure is 0.4 Pa, the radio frequency power applied to the target material is 300 W, and the bias voltage is set to 1000 V.

[0032] Step 2: An In2O3 film thermoelectric arm is prepared by a radio frequency magnetron sputtering method. The target material is selected to be more than 99.99% In2O3 target, the chamber pressure is not more than 4.0 x 10 －4 Pa, the substrate heating temperature is 450℃, the sputtering pressure is 1.0 Pa, the radio frequency power applied to the target material is 120 W, the film thickness is within 2 μm, the width of the deposited thermoelectric arm is 5 mm, and the length is 50 mm.

[0033] Step 3: A three-layer ITO:X film thermoelectric arm doped with different elements is prepared. The ITO target material has a purity of 99.99%, the carbon target material has a purity of 99.999%, and the nickel target material has a purity of 99.99%. The chamber pressure is not more than 4.0 x 10 －4Pa, substrate temperature 350℃, direct current power 90W for ITO target, direct current power 15W for carbon target, sputtering 1.5h, ITO:C film with thickness less than 1μm.

[0034] Step 4: adjust substrate temperature to 250℃, nitrogen flow rate 15sccm, then direct current power 90W for ITO target, direct current power 15W for carbon target, sputtering 1.5h, ITO:C:N film with thickness less than 0.8μm.

[0035] Step 5: adjust substrate temperature to 150℃, then direct current power 90W for ITO target, direct current power 15W for carbon target, direct current power 15W for nickel target, sputtering 1.5h, ITO:C:N:Ni film with thickness less than 0.6μm; thickness of three-layer film not more than 2.0μm; width of deposited thermoelectric arm 5mm, length 50mm.

[0036] Step 6: annealing treatment for test piece. Annealing temperature 600℃, annealing time not less than 60min.

[0037] The metal workpiece is a turbine blade of a turbofan engine.

[0038] The metal workpiece is a nickel-based superalloy.

[0039] Example 2:

[0040] Step 1: ultrasonic washing of test piece or ceramic piece in deionized water, alcohol, acetone solution for 30min, then drying for standby.

[0041] Step 2: In2O3 film thermoelectric arm prepared by radio frequency magnetron sputtering. Target material selected is In2O3 target with purity more than 99.99%, chamber pressure not more than 4.0×10 －4 Pa, substrate heating temperature 450℃, sputtering gas pressure 1.0Pa, radio frequency power 120W for target material, film thickness within 2μm, width of deposited thermoelectric arm 5mm, length 50mm.

[0042] Step 3: three-layer X-ITO film thermoelectric arm prepared by doping different elements. ITO target material with purity 99.99%, carbon target material with purity 99.999% and nickel target material with purity 99.99% are selected, chamber pressure not more than 4.0×10 －4 Pa, substrate temperature 350℃, direct current power 90W for ITO target, direct current power 15W for carbon target, ITO:C film with thickness less than 1μm.

[0043] Step 4: Adjust the substrate temperature to 250℃, and then introduce nitrogen gas at a flow rate of 15sccm, and then apply a direct current power of 90W to the ITO target and a direct current power of 15W to the carbon target to obtain an ITO:C:N film with a film thickness of less than 0.8μm.

[0044] Step 5: Adjust the substrate temperature to 150℃, and then apply a direct current power of 90W to the ITO target, a direct current power of 15W to the carbon target, and a direct current power of 15W to the nickel target to obtain an ITO:C:N:Ni film with a film thickness of less than 0.6μm; the thickness of the three-layer film is not greater than 2.0μm; and the width of the deposited thermoelectric arm is 5mm and the length is 50mm.

[0045] Step 6: Anneal the test piece. The annealing temperature is 600℃, and the annealing time is not less than 60min.

[0046] The ceramic piece is an alumina ceramic.

[0047] Example 3:

[0048] Step 1: Deposit an alumina transition layer on the surface of the test piece or metal piece by a magnetron sputtering deposition process, and the deposition thickness is not more than 2.0μm. The target material is selected to be an alumina target with a purity of 99.99%, the chamber pressure is not greater than 4.0×10 －4 Pa, the substrate heating temperature is 450℃, the sputtering gas pressure is 0.5Pa, a radio frequency power of 350W is applied to the target material, and the bias voltage is set to 1100V.

[0049] Step 2: Prepare an In2O3 film thermoelectric arm by a radio frequency magnetron sputtering method. The target material is selected to be an In2O3 target with a purity of more than 99.99%, the chamber pressure is not greater than 4.0×10 －4 Pa, the substrate heating temperature is 420℃, the sputtering gas pressure is 0.8Pa, a radio frequency power of 100W is applied to the target material, the film thickness is within 2μm, the width of the deposited thermoelectric arm is 5mm, and the length is 50mm.

[0050] Step 3: Prepare a three-layer ITO:X film thermoelectric arm doped with different elements. The ITO target material has a purity of 99.99%, the carbon target material has a purity of 99.999%, and the nickel target material has a purity of 99.99%, the chamber pressure is not greater than 4.0×10 －4 Pa, the sputtering gas pressure is 0.5Pa, the substrate temperature is 370℃, a direct current power of 100W is applied to the ITO target, and a direct current power of 17W is applied to the carbon target to obtain an ITO:C film with a film thickness of less than 1μm;

[0051] Step 4: Adjust the substrate temperature to 270℃, and then introduce nitrogen gas at a flow rate of 17sccm, and then apply a direct current power of 100W to the ITO target and a direct current power of 17W to the carbon target to obtain an ITO:C:N film with a film thickness of less than 0.8μm;

[0052] Step 5: Adjust the substrate temperature to 170°C, then apply direct current power of 100W to the ITO target, direct current power of 17W to the carbon target, and direct current power of 17W to the nickel target to obtain an ITO:C:N:Ni film, the film thickness is less than 0.6μm; the thickness of the three-layer film is not more than 2.0μm;

[0053] Step 6: Anneal the test piece. The annealing temperature is 600°C, and the annealing time is not less than 60min.

[0054] The test piece is a turbine blade of a turbofan engine.

[0055] The test piece is a nickel-based superalloy.

[0056] The description of the different advantageous arrangements has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the examples disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art. Different advantageous examples can provide different advantages, and no particular advantage is necessarily required of any advantageous example. The chosen examples or examples are described to best explain the principles of the examples and the practical application, and to enable others skilled in the art to best utilize the examples in various and numerous embodiments and with various modifications as are suited to the particular use contemplated.

Claims

1. A method for preparing a ceramic oxide thin film thermocouple for temperature measurement of an aeroengine, characterized in that, The preparation method comprises the following steps: Step 1, test piece pretreatment When the test piece is made of metal, an insulating layer with a thickness of 1.5-2.5 μm is deposited on the surface of the test piece by a magnetron sputtering process; when the test piece is made of ceramic, the surface of the test piece is cleaned; Step 2, preparation of In2O3 thin film thermoelectric arm A first mask is installed on the surface of the test piece, and an opening is formed on the mask, so that the opening shape corresponds to the In2O3 thermoelectric arm region; an In2O3 thin film with a thickness of 2 μm or less is deposited in the opening by a magnetron sputtering process; The magnetron sputtering parameters are as follows: the initial vacuum pressure of the vacuum chamber is not more than 4.0*10 -4 Pa, the sputtering pressure after filling argon is 0.8 Pa to 1.5 Pa, the heating temperature is 400 to 500 DEG C, the sputtering target material is In2O3 target material, the direct current power is 80 W to 150 W, and the metal workpiece is naturally cooled to room temperature after sputtering. Step 3, preparation of X-ITO thin film thermoelectric arm The first mask is replaced by a second mask on the surface of the test piece, and an opening is formed on the second mask, so that the opening shape corresponds to the X-ITO thermoelectric arm region; An X-ITO thin film is deposited in the opening by a magnetron sputtering process; ITO is indium tin oxide, and X represents a doping element; the magnetron sputtering process includes an ITO target, a carbon target and a nickel target; the magnetron sputtering process is divided into three continuous stages; The first stage magnetron sputtering parameters are as follows: the sputtering target is ITO target and carbon target working simultaneously, the initial vacuum pressure of the vacuum chamber is not more than 5.0x10 -3 Pa, the sputtering pressure after filling argon is 0.2Pa~0.6Pa, the heating temperature is 300~400℃, the ITO target direct current power is 50~150 W, the carbon target direct current power is 50 W or less; the first stage deposition thickness is 1.0 μm or less, the target is closed after reaching the thickness, and the temperature is controlled to reduce to 200~300℃; In the second stage, the magnetron sputtering parameters are as follows: while maintaining the inflow of argon, nitrogen is introduced, and the flow rate ratio of nitrogen to argon is 1:1-1:15; after the introduction of nitrogen, the ITO target and the carbon target are turned on, the initial vacuum pressure of the vacuum chamber remains unchanged, the sputtering gas pressure remains unchanged, the heating temperature is maintained at 200-300 ℃, the direct current power of the ITO target is 50-150 W, and the direct current power of the carbon target is 50 W or less; the thickness deposited in the second stage is 0.8 μm or less, the target is turned off after reaching the thickness, and the temperature is controlled to decrease to 100-200 ℃; In the third stage, the magnetron sputtering parameters are as follows: the flow rates of argon and nitrogen remain unchanged; the ITO target, the carbon target and the nickel target are turned on, the initial vacuum pressure of the vacuum chamber remains unchanged, the heating temperature is maintained at 100-200 ℃, the direct current power of the ITO target is 50-150 W, the direct current power of the carbon target is 50 W or less, and the direct current power of the nickel target is 50 W or less; the thickness deposited in the third stage is 0.6 μm or less, the magnetron sputtering process is ended after reaching the thickness, and the temperature is naturally cooled to room temperature; Step 4, annealing treatment The test piece is subjected to annealing treatment, and the annealing temperature is 550-700 ℃, and the annealing time is not less than 60 min.

2. The method of claim 1, wherein the method further comprises: depositing a first layer of a first ceramic oxide material on the substrate; depositing a second layer of a second ceramic oxide material on the first layer; and depositing a third layer of a third ceramic oxide material on the second layer. The purity of the nitrogen is 99.999%.

3. The method of claim 1, wherein the method further comprises: depositing a first layer of a first ceramic oxide material on the substrate; depositing a second layer of a second ceramic oxide material on the first layer; and depositing a third layer of a third ceramic oxide material on the second layer. The flow rate of the nitrogen is not more than 18 sccm.

4. The method of claim 1, wherein the method further comprises: depositing a first layer of a first ceramic oxide material on the substrate; depositing a second layer of a second ceramic oxide material on the first layer; and depositing a third layer of a third ceramic oxide material on the second layer. The purity of the ITO target is 99.99%.

5. The method of claim 1, wherein the method further comprises: depositing a ceramic oxide film on the substrate; and depositing a metal film on the ceramic oxide film. The purity of the carbon target is 99.999%.

6. The method of claim 1, wherein the method further comprises: depositing a ceramic oxide film on the substrate; and depositing a metal film on the ceramic oxide film. The purity of the nickel target is 99.99%.

7. The method of claim 1, wherein the method further comprises: depositing a ceramic oxide film on the substrate; and depositing a metal film on the ceramic oxide film. The test piece is a turbine blade of a turbofan engine.

8. The method of claim 1, wherein the method further comprises: depositing a ceramic oxide film on the substrate; and depositing a metal film on the ceramic oxide film. The material of the test piece is a nickel-based high-temperature alloy.