| As the core hot end component of aero-engine,turbine blade is easy to be damaged due to long-term high temperature extreme environment,so it is necessary to control and detect the temperature of turbine blade.In order to accurately measure the real-time temperature of turbine blade,platinum(Pt)thin film resistance temperature detector(RTD)was fabricated on its surface.Compared with the traditional temperature measurement method,Pt thin film RTD was widely used in temperature measurement because of its advantages such as easy to be integrated,small volume,high sensitivity,wide temperature measurement range,short corresponding time and strong anti-vibration performance.In order to prepare thin film RTD with strong adhesion and high performance on the surface of Ni-based superalloy turbine blade,a thin film temperature sensor with multilayer structure was designed in this paper,including: transition layer,thermal grown oxidation(TGO)layer,insulation layer and Pt thin film function sensitive layer.And annealing heat treatment was used to effectively improve the sensing properties of the sensors,thereby preparing the thin film RTD with good high-temperature performance.The main contents of this paper include:1.In order to realize the high-temperature electrical insulation between Ni-based superalloy turbine blade and Pt thin film to avoid the failure of temperature measurement due to the direct conduction between them,a Ni Cr Al Y transition layer was prepared on the turbine blade surface by DC magnetron sputtering.Then,a dense and uniform TGO layer was formed through the process of segregation and oxidation,finding that the hightemperature insulation resistance of TGO layer was not enough to meet the high temperature insulation requirements of the RTD.2.Alumina insulation layers with different layer structures were prepared on the surface of TGO layer by electron beam evaporation to further improve the hightemperature insulation properties of the samples.Moreover,the microstructure and high temperature insulation performance of single-layer,double-layer and three-layer alumina insulation layers were studied,showing that: The three-layer alumina insulation layer has the most uniform and dense microstructure,the least defects,the strongest crystallization degree and the best high-temperature insulation performance,whose insulation resistance was as high as 43.1k? at 800 ?,which met the high temperature insulation requirement between the turbine blade surface and RTD.3.Pt thin film function sensitive layer was prepared on the surface of insulation layer by the means of patterned mask and electron beam evaporation.Then,the effects of different annealing temperatures(annealing at 450?,650? and 800? for 2h)and different annealing time(annealing at 800? for 1h,2h,4h and 6h)on the RTD were studied.Then the temperature measurement error,stability and repeatability of the samples were quantitatively tested,indicating that: With the increase of annealing temperature and annealing time,the crystallization of Pt thin films was gradually enhanced and the defects of the films were gradually decreased,the temperature coefficient of resistance(TCR)and the sensitivity of the RTD were gradually increased,and the linearity and the temperature measurement error of the RTD were gradually reduced.After annealing at 800? for 6h with atmospheric atmosphere,the TCR of the RTD was more than 2500ppm/?,and it had ideal sensitivity,linearity,stability and repeatability.It showed that annealing heat treatment could significantly improve the temperature measurement performance of the RTD,so as to ensure the accuracy,reliability and durability of the temperature measurement on the surface of turbine blade by the RTD with the multilayer structure. |
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