Metal Nitride Thin Film Ultrasonic Temperature Sensor and Temperature Measurement Method

Abstract

The present application discloses a metal nitride thin film ultrasonic temperature sensor and a temperature measurement method. The material of the temperature sensor is a piezoelectric coating of metal nitride, and the change of the ultrasonic wave excited on the coating surface (including the piezoelectric signal intensity, the acoustic time delay, and the acoustic wave frequency) is used to characterize the change of temperature, so as to feedback the temperature to be measured in real time. This technical solution provides a metal nitride thin film ultrasonic temperature sensor that operates stably within a wide temperature range, monitors the temperature in real time, realizes online early warning of temperature changes, and prevents serious consequences caused by high-temperature creep and structural fracture.

Description

Technical Field

[0001] This application relates to the technical field of temperature measurement, and particularly to a nitride thin film ultrasonic temperature sensor and a temperature measurement method. Background Art

[0002] Aero-engine and the like work under high temperature, high pressure, high load and high speed for a long time, which will lead to a reduction in the reliable working life of the hot-end components, a decrease in material strength, resulting in creep or even fracture of the hot-end materials, causing serious consequences. Therefore, accurately measuring the temperature of the components, realizing performance monitoring and life prediction, and reducing accidents caused by high temperature are of great significance.

[0003] In view of the complex environment inside the aero-engine, a variety of temperature measurement technologies have been developed. The most mature ones include crystal temperature measurement technology, temperature indicating paint temperature measurement method, fluorescence temperature measurement method, radiation temperature measurement technology, etc.

[0004] However, the crystal used in the crystal temperature measurement technology needs to be buried in the object to be measured. Therefore, holes need to be drilled on the surface of the object to be measured, which will largely damage the object to be measured, reduce its life, and have quite high requirements for the strength of the object to be measured. The temperature indicating paint temperature measurement method measures the ambient temperature through the change of the color of the temperature indicating paint. It can only measure the highest temperature of the hot-end components, cannot perform real-time monitoring, and has a low temperature resolution. Secondly, the irreversible temperature indicating paint cannot be used continuously. Each time the temperature is measured, the blade needs to be disassembled to paint and interpret. At the same time, the color change of the temperature indicating paint will be affected by the heating speed, time, and environmental pollution, resulting in its temperature measurement accuracy being lower than that of general temperature measurement methods. Moreover, the process of interpreting the color of the temperature indicating paint is interfered by human experience factors and has low accuracy. The fluorescence temperature measurement method has problems with fluorescence materials and coupling, and cannot be applied to the temperature measurement of aero-engine turbine blades for the time being. The radiation temperature measurement technology is a method of obtaining the temperature value by collecting the thermal radiation emitted from the surface of the object to be measured. However, it is easily scattered due to the absorption of gases in the air, and is also easily affected by the reflected radiation of other objects, and the temperature measurement accuracy needs to be further improved.

[0005] Therefore, it is necessary to develop a more effective real-time temperature measurement technology to obtain the temperature field distribution of aero-engine blades and realize real-time temperature monitoring. Summary of the Invention

[0006] In view of this, this application provides a metal nitride thin film ultrasonic temperature sensor and a temperature measurement method, which can reflect the influence of the temperature to be measured through the change of the ultrasonic parameters excited on the piezoelectric coating surface of the metal nitride, and then accurately and real-timely feedback the temperature change.

[0007] In a first aspect, the present application provides a metal nitride thin film ultrasonic temperature sensor, which includes a piezoelectric coating of metal nitride. The piezoelectric coating is configured to characterize the change in temperature through the change in ultrasonic parameters of the coating, so as to provide real-time feedback on the temperature to be measured.

[0008] In a second aspect, the present application provides a temperature measurement method, which is implemented using the nitride thin film temperature sensor as described above.

[0009] Suitably but not restrictively, the implementation process includes the following steps:

[0010] (1) Provide the piezoelectric coating covering the object to be measured, and an electrode layer is covered on the surface of the piezoelectric coating to form a metal nitride thin film ultrasonic temperature sensor;

[0011] (2) Anneal the object to be measured and the metal nitride thin film ultrasonic temperature sensor;

[0012] (3) Measure the change in ultrasonic parameters;

[0013] (4) Reflect the temperature change according to the change in ultrasonic parameters to achieve real-time temperature measurement.

[0014] Suitably but not restrictively, the preparation methods of the metal nitride piezoelectric coating and the electrode layer are radio frequency magnetron sputtering.

[0015] Suitably but not restrictively, the metal nitride is AlN and / or AlScN, with a thickness of 12 - 20 microns.

[0016] Suitably but not restrictively, the deposition parameters of the AlN piezoelectric coating are as follows: using an Al target, the power of radio frequency magnetron sputtering is 600 - 1000W, the deposition pressure is 0.5 - 4Pa, Ar / O2 is 1 / 3 - 4 / 1, the chamber temperature is 80 - 250°C, the deposition time is 2h - 10h, and the distance between the target and the substrate is 2cm - 7cm.

[0017] Suitably but not restrictively, the deposition parameters of the AlScN piezoelectric coating are as follows: using a mixed target of Al:Sc = 1:9 - 5:5, the power of radio frequency magnetron sputtering is 600 - 1000W, the deposition pressure is 0.5 - 4Pa, Ar / O2 is 1 / 2 - 4 / 1, the chamber temperature is 80 - 250°C, the deposition time is 2h - 10h, and the distance between the target and the substrate is 2cm - 7cm.

[0018] Suitably but not restrictively, the electrode layer is Ag or Cr, with a thickness of 15 - 25 μm, and the deposition parameters are as follows: using a high-purity Ag target or Cr target, the radio-frequency magnetron sputtering power is 500 - 1000 W, the deposition pressure is 0.5 - 3 Pa, pure argon gas, the temperature inside the chamber is 80 - 250 °C, the deposition time is 2 h - 10 h, and the distance between the target and the substrate is 2 cm - 7 cm.

[0019] Suitably but not restrictively, the heating rate of the annealing furnace is 2 °C / min - 5 °C / min, and the maximum temperature is 400 - 1000 °C.

[0020] Suitably but not restrictively, the changes in the ultrasonic parameters include analyzing the piezoelectric signal intensity, acoustic time delay, and acoustic wave frequency magnitude.

[0021] This application has the following advantages and beneficial effects:

[0022] First, the selected temperature-sensing material is nitride. Nitride has a unique wurtzite structure, high Curie temperature, radiation resistance, resistivity, etc. The AlN thin film is an excellent choice for high-temperature temperature sensors due to its high Curie temperature of up to 2800 °C and excellent radiation resistance. AlScN has a high electromechanical coupling coefficient and piezoelectric coefficient.

[0023] Second, the temperature-sensing material used in this application is a metal nitride thin film with a thickness of about 10 μm - 20 μm. Compared with fluorescence thermometry, there is no coupling problem in this application technology. Compared with crystal thermometry technology, first, the thin film has a higher adhesion force to the substrate and the object to be measured than the crystal. Second, since the thin film is directly grown on the object to be measured, there is no need to open holes for burying, which will not cause damage to the structure of the object to be measured, and there is no requirement for the strength of the object to be measured. Moreover, no additional adhesive is needed, and temperature monitoring can be achieved.

[0024] Third, the thin film used in this application is deposited on the object to be measured by radio-frequency magnetron technology. Compared with thin-film preparation technologies such as laser pulse deposition, electron beam evaporation, and sol-gel method, the radio-frequency sputtering method is a relatively mature piezoelectric thin-film preparation technology at present. Its preparation temperature is low, which will not affect the mechanical properties of the substrate, and the deposition parameters can be adjusted to obtain a piezoelectric thin-film material with a preferred orientation.

[0025] Fourth, the measurement target for measuring temperature changes used in this application is the excited ultrasonic wave (including piezoelectric signal, acoustic time, and acoustic wave frequency). Compared with the thermochromic paint thermometry method, the measurement results of this application are all obtained through measuring instruments, avoiding human factor interference and having high precision. Compared with radiation thermometry technology, it is not affected by other environmental factors such as air and surrounding objects. Description of the Drawings

[0026] The following will, in conjunction with the accompanying drawings, make the technical solutions and other beneficial effects of the present application obvious through a detailed description of the specific embodiments of the present application.

[0027] Figure 1 It is a graph showing the influence relationship between the ultrasonic signal and temperature in Example 2.

[0028] Figure 2 It is a graph showing the influence relationship between the flight time and temperature in Example 2.

[0029] Figure 3 It is a graph showing the influence relationship between the ultrasonic frequency and temperature in Example 2.

[0030] Figure 4 It is a graph showing the variation relationship of the acoustic wave frequency with temperature in Example 2. Specific Embodiments

[0031] For a better understanding of the present invention, the following embodiments are further descriptions of the present invention, but the content of the present invention is not limited to the following embodiments.

[0032] Example 1:

[0033] Prepare a metal nitride thin film ultrasonic temperature sensor: Use radio frequency magnetron sputtering technology to deposit a metal nitride thin film and an electrode layer on the surface of the object to be measured, forming a temperature sensor integrated with the object to be measured.

[0034] In this way, compared with fluorescent materials, it is not easy to fall off and there is no coupling problem.

[0035] Transfer the object to be measured and the metal nitride thin film ultrasonic temperature sensor together to a high-temperature annealing furnace: Set the temperature rising rate and the highest temperature of the annealing furnace;

[0036] Measure the change of the ultrasonic waves (including but not limited to ultrasonic signals, acoustic time, acoustic wave frequency) excited by the metal nitride thin film ultrasonic temperature sensor with temperature;

[0037] Combine the change of the ultrasonic waves (including ultrasonic signals, acoustic time, acoustic wave frequency) excited by the coating to achieve the goal of real-time temperature feedback.

[0038] Preferably, the metal nitride includes AlN, AlScN and a composite coating of both, with a thickness of 12 - 20 microns.

[0039] Preferably, the deposition parameters of the AlN piezoelectric coating are as follows: Use a high-purity Al target, the RF power is between 600 - 1000W, the deposition pressure is between 0.5 - 4Pa, the Ar / O2 is between 1 / 3 - 4 / 1, the chamber temperature is between 80 - 250°C, the deposition time is between 2h - 10h, and the distance between the target and the substrate is between 2cm - 7cm.

[0040] Preferably, the deposition parameters of the AlScN piezoelectric coating are as follows: a mixed target with Al:Sc = 1:9 to 5:5 is used, the power of RF magnetron sputtering is 600 - 1000 W, the deposition pressure is 0.5 - 4 Pa, Ar / O2 is 1 / 2 - 4 / 1, the temperature inside the chamber is 80 - 250 °C, the deposition time is 2 h - 10 h, and the distance between the target and the substrate is 2 cm - 7 cm.

[0041] Preferably, the electrode layer is Ag or Cr, with a thickness of 15 - 25 microns, and the deposition parameters are as follows: a high-purity Ag target or Cr target is used, the RF power is between 500 - 1000 W, the deposition pressure is between 0.5 - 3 Pa, pure argon gas, the temperature inside the chamber is between 80 - 250 °C, the deposition time is between 2 h - 10 h, and the distance between the target and the substrate is between 2 cm - 7 cm.

[0042] Preferably, the temperature rising rate of the annealing furnace is between 2 °C / min - 5 °C / min, and the maximum temperature is between 400 - 1000 °C.

[0043] Example 2:

[0044] A metal nitride thin film ultrasonic temperature sensor and its real-time temperature measurement method provided by the present invention use a homogeneous nitride piezoelectric coating as the temperature sensor material, and the changes in ultrasonic waves (including piezoelectric signal intensity, acoustic time delay, and acoustic wave frequency) excited by the coating are used to real-time feedback the substrate / environment temperature.

[0045] Combined with Figures 1 - 3 , a piezoelectric coating is deposited on a stainless steel sheet, and the feasibility of real-time monitoring of the ultrasonic signal of the coating for temperature is verified.

[0046] (1) Prepare a metal nitride thin film ultrasonic temperature sensor: Use RF magnetron sputtering technology to deposit a nitride thin film and an electrode layer on the surface of the object to be measured, forming a sensor integrated with the object to be measured. Among them, the RF deposition parameters of the AlN thin film are as follows: the RF power is 900 W, the deposition pressure is 2 Pa, Ar / O2 is 2 / 1, the temperature inside the chamber is 150 °C, the deposition time is 8 h, and the distance between the target and the substrate is 5 cm. The deposition parameters of the Ag electrode layer are as follows: the RF power is 800 W, the deposition pressure is 2 Pa, the temperature inside the chamber is 120 °C, the deposition time is 2 h, and the distance between the target and the substrate is 4 cm.

[0047] (2) Transfer the object to be measured and the metal nitride thin film ultrasonic temperature sensor to a high-temperature annealing furnace: Set the temperature rising rate of the annealing furnace to 5 °C / min and the maximum temperature to 900 °C;

[0048] (3) Measure the changes in ultrasonic waves (including piezoelectric signals, acoustic time delay, and acoustic wave frequency) excited by the metal nitride thin film ultrasonic temperature sensor with temperature;

[0049] (4) The goal of real-time temperature feedback is achieved by combining the changes in ultrasonic waves (including piezoelectric signals, acoustic time delay, and acoustic wave frequency) excited by the coating.

[0050] The delayed excitation ultrasonic signal changes with temperature as shown in Figures 1 - 2 It is obvious that as the ambient temperature (i.e., the temperature of the stainless steel sheet) rises, the measured ultrasonic signal gradually decreases, especially when the temperature is higher than 600°C, the ultrasonic signal drops sharply.

[0051] The flight time of the delayed excited sound wave changes with temperature as shown in Figure 3 As the ambient temperature (i.e., the temperature of the stainless steel sheet) rises, the measured flight time also gradually increases. This is because the high temperature causes the stainless steel sheet to expand, the distance the sound wave moves increases, and the flight time is prolonged. Moreover, the higher the ambient temperature, the more violently the stainless steel sheet expands.

[0052] The frequency of the delayed excited sound wave changes with temperature as follows Figure 4 ,As the ambient temperature (i.e. the temperature of the stainless steel sheet) rises, the measured sound wave frequency gradually decreases.

[0053] Therefore, by comparing the ultrasonic signal, flight time, sound wave frequency and normal temperature data, the ambient temperature of the stainless steel sheet can be fed back.

[0054] The above is only a preferred specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed in the present application should be covered within the protection scope of the present application.

Claims

1. A metal nitride thin film ultrasonic temperature sensor, characterized in that, The temperature sensor body is a piezoelectric coating of nitride, which can characterize the change of temperature in real time through the change of the excited ultrasonic parameters, and feedback the temperature to be measured online; The piezoelectric coating is a metal nitride, and the metal nitride is AlN or AlScN, with a thickness of 12 - 20 microns; an electrode layer is covered on the surface of the piezoelectric coating; the preparation methods of the piezoelectric coating of metal nitride and the electrode layer are radio frequency magnetron sputtering; The deposition parameters of the AlN piezoelectric coating are as follows: using an Al target, the power of radio frequency magnetron sputtering is 600 - 1000W, the deposition pressure is 0.5 - 4Pa, Ar / O2 is 1 / 3 - 4 / 1, the temperature in the cavity is 80 - 250°C, the deposition time is 2h - 10h, and the distance between the target and the substrate is 2cm - 7cm; The deposition parameters of the AlScN piezoelectric coating are as follows: using a mixed target of Al:Sc = 1:9~5:5, the power of radio frequency magnetron sputtering is 600 - 1000W, the deposition pressure is 0.5 - 4Pa, Ar / O2 is 1 / 2 - 4 / 1, the temperature in the cavity is 80 - 250°C, the deposition time is 2h - 10h, and the distance between the target and the substrate is 2cm - 7cm; The electrode layer is Ag or Cr, with a thickness of 15 - 25 microns, and the deposition parameters are as follows: using a high-purity Ag target or Cr target, the power of radio frequency magnetron sputtering is 500 - 1000W, the deposition pressure is 0.5 - 3Pa, pure argon gas, the temperature in the cavity is 80 - 250°C, the deposition time is 2h - 10h, and the distance between the target and the substrate is 2cm - 7cm.

2. A temperature measurement method, characterized in that, It is implemented by using the metal nitride thin film ultrasonic temperature sensor as described in claim 1, and the implementation process includes the following steps: (1) Provide the piezoelectric coating of metal nitride covered on the object to be measured, and an electrode layer is covered on the surface of the piezoelectric coating to form a metal nitride thin film ultrasonic temperature sensor; (2) Anneal the object to be measured and the metal nitride thin film ultrasonic temperature sensor; (3) Measure the change of ultrasonic parameters; (4) Reflect the change of temperature according to the change of ultrasonic parameters to realize real-time temperature measurement.

3. The temperature measurement method according to claim 2, wherein The rising rate of the annealing furnace temperature is 2°C / min - 5°C / min, and the maximum temperature is 400 - 1000°C.

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