Study On Probe Type Metal-semiconductor Thin Film Thermocouple Temperature Sensor Based On MEMS Technology

In the aerospace field,the surface temperature of supersonic aircraft rises sharply due to air friction,and the temperature of the inner wall surface of the turbine engine and the temperature of the combustion chamber outlet also rises with the demand for high thrust-to-weight ratio.Timely obtaining the temperature information of high temperature components is very important to improve the thermal protection of the overall structure and to monitor the health of high temperature components.At present,the traditional armored thermocouples are most commonly used to measure high temperature field.However,traditional armored thermocouples have low sensitivity and slow response speed.And because the actual temperature measurement environment is more complicated,it is not easy to assemble and use.Based on actual engineering requirements and the principle of Seebeck effect,The probe-type thin-film thermocouples was designed and studied,including three-dimensional cylindrical structure design,thermoelectric and substrate material selection,lead connection,thermoelectric simulation and thermal stress simulation verification.By studying the thin films preparation process with MEMS technology,designing and optimizing the preparation process of magnetron sputtering suitable for three-dimensional structure,the optimal sputtering placement angle was proposed to be 45°.And the influence of magnetron sputtering parameters on the electrode film deposition rate was studied to provide process optimization for the control of the film thickness of the prepared film.In order to make the sensor have a large sensitivity output,the combination of WRe26-In₂O₃with the opposite Seebeck coefficient was selected.The In₂O₃film was analyzed by SEM,XRD and XPS analysis methods.the static thermoelectric output test result of thin films thermocouple under different annealing processes were compared to obtain the optimal annealing process of In₂O₃films.And the influence of magnetron sputtering parameters on the thermoelectric performance of WRe26-In₂O₃thermocouple was studied.then,the magnetron sputtering parameters were determined.Finally,the thermoelectric performance test of the sensor and the actual small turbine engine impact test were carried out.The test results showed that the probe-type WRe26-In₂O₃thin-film thermocouple could measure the highest temperature up to 1000℃with two seconds,the transient shock temperature could reach 1000℃,the highest static calibration temperature could reach 840℃,and its sensitivity coefficient could reach 215.7μV/℃,and it could work stably for 2h at500℃.And the repeatability error of the thermocouple was 0.79%in the static test from room temperature to 600℃.The hysteresis was 4.53%in the cycle of heating from 400℃to800℃.The dynamic response time of the sensor was 7ms.And the sensor could work stably under 0.5Ma,809℃with five seconds airflow impact in the actual small turbine engine impact test.