Research On Fabrication And Stability Of Temperature Sensor On Metal Substrate

Hot-end components,such as high-speed rotating shafts and aero-engines,have the characteristics of complex structure and small space.It is hard to use conventional temperature measurement methods such as infrared temperature measurement and wire thermocouple for temperature measurement.And obtaining the surface temperature information of these hot-end components is crucial for monitoring the working status of the components and thermal simulation verification.Therefore,the flexible thin-film sensor that can work in a higher temperature range and is easy to integrate with heterogeneous components has important research value and broad application prospects under the above-mentioned extreme environments.In this thesis,the surface temperature test of complex hot-end components is the research background,and the flexible Hastelloy tape is selected as the substrate.Combined with the advantages of thin film thermal resistance,such as small size and easy integration,the design,preparation and performance of Pt thin film sensors were studied,and the differences of Pt thin film temperature sensors on Hastelloy base tape and ceramic substrates were compared.First,the preparation process of the film was studied.Through process optimization,a better Pt film preparation process is obtained,and the effect of annealing on the film is analyzed.After annealing,the Pt film grains grow significantly and the resistivity is also significantly reduced.The process of oxidation of aluminum is optimized,it not only facilitates the subsequent preparation of the insulating layer,but also improves the adhesion between the sensor and the baseband,and also reduces the stress between the metal substrate and the insulating layer.Using Al ON/Al₂O₃ composite insulating layer for functional layer and substrate insulation treatment.Amorphous Al ON can block the diffusion of metal atoms in high temperature and sputtering processes and release thermal shock and stress generated during bending.Alumina is excellent high-temperature insulation,the composite insulating layer has excellent stress relief while ensuring high-temperature insulation,and the insulation resistance is still greater than 1M?at 800°C.Secondly,the preparation and stability of the sensor were studied.After the graphic design of the sensor,the size of the sensor and the thickness of the sensor are clarified,and the sensor is prepared.The effect of annealing on the stability of the device was studied,and the optimal annealing temperature was determined to be 600?through calibration tests.The stability and linearity of the device after annealing were greatly improved,and the TCR value reached the highest of 2790ppm/?.The influence of the protective layer on the stability of the sensor was further studied.A protective layer of aluminum oxide was prepared on the surface of the sensor by reactive sputtering,and the calibration was carried out in the same calibration environment.With the increase of the number of calibrations cycles,the sample with a protective layer still shows better stability when the number of calibration increases.Since the protective layer plays a role in reducing the oxygen diffusion rate in the environment,it shows that the protective layer plays a better role in increasing the stability of the device.The protective layer also plays a role in increasing the service life of the sensor in harsh environments and has a certain protective effect on the functional layer.Finally,the hysteresis performance,bending performance and response time of the temperature sensor are tested and analyzed.The maximum hysteresis of the temperature sensor on the flexible Hastelloy baseband is about 1%,which is better than the traditional temperature sensor on the ceramic base,at the same better annealing temperature,the sensor on the Hastelloy base tape in the calibration temperature range from room temperature to 550?exhibits better linearity,better stability and smaller thermal hysteresis than the sensor on the alumina ceramic substrate,and its nonlinearity is only0.07%.The temperature sensor on the Hastelloy base tape has a maximum bending curvature of 2cm^-1 during the bending test,and the resistance change is small under the maximum bending,and the resistance change rate decreases with the increase of the bending curvature.The sensor film is still attached intact after eight times of bending for more than half an hour,and has good bending resistance.The thin-film temperature sensor also has a faster response,with a response time of 247?s.Compared with traditional temperature sensors,sensor on the flexible Hastelloy baseband has the advantages of fast response,small size,and easy integration of large components.It has high temperature resistance and good flexibility,and it can also be integrated on the surface of some irregular hot end parts by welding with little affecting on the component's surface flow field.It is helpful to solve the temperature measurement problems of some high-temperature complex surfaces.