| The high-temperature strain sensor is a miniature sensor which monitors the strain of the test piece in a high-temperature environment.And most of the currently available high-temperature thin-film strain sensors use the metallic materials as sensitive materials,which greatly limits the application temperature of the sensor.Therefore,ceramic materials with better high temperature resistance are applied as sensitive materials in this paper.The preparation process of sensitive layer and insulating layer in laminated ceramic high temperature thin film strain sensor that suitable for higher temperature were explored.And the structural parameters of the thin film strain sensor were optimized by simulation.?1?The effects of nitrogen partial pressure and heat treatment temperature that on the properties of ITO thin films were studied.And ITO thin film was prepared on alumina ceramic substrate by magnetron sputtering technology.With the control of other sputtering parameters unchanged,the effect of nitrogen partial pressure in the sputtering atmosphere on the sputtering rate,surface morphology,phase structure and electrical properties of the thin film were explored.The properties of the sputtered film should be improved by heat treatment.Moreover,the influence of heat treatment temperature on the surface morphology,physical phase structure and electrical properties of thin films were investigated.Finally,the partial pressure of sputtering nitrogen of ITO film was determined to be 20%.The heat treatment process was to heat up the film from room temperature to 1000?at the rate of 5?/min in the atmosphere,and then cool it naturally after 2 hours of heat preservation.The results indicate that the resistivity of the ITO film prepared by the above process conditions is2.04×10-1?·cm,and the TCR is-773 ppm/?.?2?Various preparation methods and high-temperature properties of laminated insulating films were explored.The alumina sol and alumina mixture were prepared as insulating materials.An alumina mixture insulating film and an alumina mixture/sol composite insulating film were prepared on a silicon substrate by electro-jet deposition technology,and an alumina mixture/silicon nitride composite insulating film was prepared by liquid-vapor alternate deposition method.The insulation resistance value of the insulation films in the temperature range of 50-1200?were tested.The results display that the resistance values of alumina mixture insulating film,alumina mixture/sol composite insulating film and alumina mixture/silicon nitride composite insulating film at 1200?are 38K?,93K?and 54K?,respectively.What's more,the surface morphologies of alumina mixture and alumina mixture/sol composite insulating films were observed by scanning electron microscope?SEM?.The results show that the composite insulating film has a tighter and smoother surface.It is prove that the composite insulation film can effectively improve the surface morphology and high temperature insulation performance.?3?The structural parameters that based on optimized strain sensor thermal stress and strain transfer error were explored.According to the design criteria of the strain sensors,strain sensors with different structural parameters were designed.The simulation model of strain sensors under thermal stress in high temperature environment and tensile load at room temperature were established.The influences of insulation layer thickness,sensitive layer thickness,protective layer thickness and sensitive gate structure on the main stress of each layer,the shear stress between each layer and the strain transfer error of the strain sensor were analyzed by using the orthogonal test method.The optimized structural parameters of the strain sensor are as follows:the membrane strain sensor of the four-gate filaments with the thickness of insulation layer is 10?m,the thickness of the sensitive layer is 0.25?m,and the thickness of the protective layer is 10?m.According to the simulation results,ITO sensitive gate was prepared. |
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