Research On SAW Temperature Sensor Based On LGS And High Temperature Electrode Protection

With the rapid development of China’s aerospace industry,the real-time temperature monitoring needs for the engine and other key parts of aircraft are more and more.In harsh environments,surface acoustic wave sensors are widely used because of their advantages such as small structure,excellent performance and wireless measurement.Because of the high temperature of the aero engine,it requires the surface acoustic wave sensor to work continuously and stably at high temperature.In this paper,a surface acoustic wave temperature sensor based on the principle of surface acoustic wave and gallium lanthanum silicate material is proposed.At the same time,by means of pulsed laser deposition(PLD),a protective film is deposited on the surface of the sensor to improve the operating temperature of the device.The research contents of this paper are as follows:1.The propagation mechanism of surface acoustic wave and the classification of surface acoustic wave sensor are studied,the basic structure of surface acoustic wave sensor is introduced,and the corresponding relationship between the structural parameters of sensor and sensor performance is established.2.The theoretical model based on the SAW sensor is analyzed,and the influence of various parameters of the sensor structure on the performance of the surface acoustic wave sensor is discussed.The resonant frequency of sensor was simulated by COMSOL Multiphysics finite element simulation software,and the relationship between electrode thickness and sound velocity was analyzed.3.By analyzing the temperature sensing principle of the SAW sensor and the principle of electrode protection under high temperature,a surface acoustic wave temperature sensor applied to high temperature based on the protective film is proposed,and the surface acoustic wave temperature sensor is designed and fabricated.4.Two kinds of surface acoustic wave temperature sensors with different protective films were prepared for high temperature test.It was tested at 25-1100℃ and 25-1300℃,and the relationship between the resonant frequency of the sensor and the temperature was piecewise fitted to improve the measurement accuracy.The sensor could be measured several times in the range of 25-1100 ℃,and it continued to work at 1100 ℃ for more than 1h.The surface morphology of the sensor before and after testing was analyzed.