Fabrication Of High Toughness Insulating Layer And Thin Film Sensor On Metallic Tapes

Temperature detection is critical in operating condition monitoring,high temperature warning,and optimal design of hot-end components.Based on the research background of the surface temperature detection of high-temperature hot-end components of aviation with complex structure,the preparation of high-toughness insulating layer film on flexible metallic tape is studied in this thesis,and the preparation and performance of thin-film thermal resistance temperature sensor are also investigated.First,the effect of the aluminum precipitation oxidation heat treatment process on the structure of the NiCrAlY transition layer was studied.It is found that the oxidation temperature,oxygen partial pressure and oxidation time will affect the surface roughness of the thermally grown oxide layer（TGO）and the formation of theθ-Al₂O₃ phase,resulting in a decrease in the ability of the TGO layer to inhibit the diffusion of elements and a serious decrease in the high temperature performance stability of the insulating layer.Using the optimized aluminum deposition oxidation process（annealing at 1000℃in vacuum for 6h,and then annealing at 950℃in 100Pa oxygen for 12h）,a TGO layer with a stable sheet-likeα-Al₂O₃ structure on the surface can be obtained,and its dense and flat structure greatly enhances the performance stability of the insulating layer.Secondly,Al ON+Al₂O₃ and YAl O+Al₂O₃composite insulating layer systems were designed and fabricated respectively,and their insulating properties and mechanical properties were tested.The research results show that the thickness ratio of Al₂O₃ film plays a decisive role in the high temperature insulation performance of the composite insulating layer.When the thickness ratio of the Al₂O₃ film is larger,the high temperature insulation performance of the insulating layer is significantly improved.In terms of mechanical properties,the Al ON+Al₂O₃ system has more advantages.In the same loading-unloading test,the Al ON+Al₂O₃ system has stronger recovery ability,and the average elastic modulus is also larger,about 210GPa,while the recovery ability of the YAl O+Al₂O₃ system is relatively poor,and the average elastic modulus is about 170GPa.Therefore,the optimized composite insulating layer is an Al ON+Al₂O₃ system,in which the thickness of the amorphous Al ON film is about 120 nm,and the thickness of the Al₂O₃film is about 600 nm.According to the requirements of engineering application,the bending resistance of the prepared composite insulating layer was investigated.The composite insulating layer prepared on the metallic tape was bent 100 times on cylinders with a radius of 1.25 cm and 0.75 cm respectively,and then fixed and bent on a cylinder with a radius of 0.75 cm for 24 hours,the composite insulating layer did not crack or fall off,and the Pt thin film thermal resistance can still work normally.Finally,the effects of two patterning processes,hard mask and photolithography,on the performance of Pt thin film thermal resistors on flexible superalloy substrates are investigated.The research results show that the thin film thermal resistors prepared by the two processes have high repeatability and similar temperature measurement accuracy in the cyclic calibration under the same conditions.There is also no significant difference in the temperature coefficient of resistance（TCR）.However,in the test of different heating and cooling rates,the thermal hysteresis effect of the thermal resistance prepared by the hard mask is obvious,and the maximum thermal hysteresis value is 2.26%.The thermal resistance prepared by the photolithography process has a relatively small thermal hysteresis effect,and the maximum thermal hysteresis is 1.39%.In addition,the thickness uniformity of the thin film thermal resistance prepared by the photolithography process is better,and there is no shadow effect.The thermal resistance samples prepared in the same batch are very similar in various temperature measurement performance and have better consistency.