Preparation And Testing Of High Temperature Resistant ITO Film Strain Gauge Based On Pulsed Laser Deposition

The efficiency and thrust of China's aerospace engines have been improving.In order to ensure the normal operation of the engine,it is very important to monitor the strain produced by turbine blades stably and accurately during operation.Thin film strain gauge is widely used in turbine blade strain measurement due to its advantages of small thickness,light weight,short response time and high accuracy.In this paper,ITO is mainly selected as the sensitive material of the thin film strain gauge,and the effects of the substrate temperature of pulsed laser deposition(PLD)and the thickness ratio of the thin film on the properties of ITO thin films and ITO/Pt composite thin films are studied,the preparation conditions of thin film strain gauge are optimized.Using the optimized preparation process,ITO film strain gauge and ITO/Pt composite film strain gauge were prepared on the ceramic cantilever beam,respectively,and their high temperature resistance and strain properties were tested.Finally,a laminated ITO/Pt film strain gauge was prepared and its high temperature resistance was tested.The main contents and conclusions are as follows:1.ITO sensitive films were prepared by pulse laser deposition on ceramic substrate.The microstructure,crystal structure,electrical properties and other properties of ITO sensitive films prepared at different substrate temperatures were tested.It was found that the deposition rate and resistivity of ITO film were the highest when the substrate temperature was 600?.When the substrate temperature is 600?,the surface grains of ITO film are more uniform,the film is more compact,and it also has the smallest resistance temperature coefficient(TCR),which is-259.575×10^-6?^-1.2.The ITO film strain gauge was prepared on the ceramic cantilever beam using the optimized process parameters,and the strain sensitivity coefficient test platform was built to test the strain performance of ITO film strain gauge.The results show that the relative resistance of ITO film strain gauge changes linearly with the applied strain,and the strain gauge factor(GF)of ITO film strain gauge is 1.57.3.According to the different high temperature sensitivity of ITO film and Pt film,the strain gauge of ITO/Pt composite film was prepared on the alumina ceramic cantilever beam substrate.The effects of different thickness ratios of ITO film and Pt film on the electrical properties and high temperature resistance of ITO/Pt composite film were studied.The strain performance of ITO/Pt composite film strain gauge at room temperature was also tested.Experiments show that the resistivity of the ITO/Pt composite thin film strain gauge increases gradually with the increase of the thickness ratio of ITO thin film to Pt thin film,while the temperature coefficient of resistance decreases slowly.When the thickness ratio of ITO film to Pt film is 5.5:1,the temperature coefficient of resistance of ITO/Pt composite film reaches the minimum,which is564.52×10^-6?^-1.The resistance value of ITO/Pt composite film strain gauge increases with the increase of strain and basically shows a linear change.The strain gauge factor(GF)of ITO/Pt composite film strain gauge at room temperature is 3.10.4.A laminated ITO/Pt film strain gauge with laminated structure was prepared and its high temperature resistance was tested.The results show that the lamination design of ITO/Pt film can significantly improve the resistance stability of the film strain gauge at high temperature.At room temperature to 1200?,the temperature coefficient of resistance of ITO/Pt lamination film strain gauge is-42.911×10^-6?^-1.