Key Technology And Research Of High Temperature Redundant Thin Film Thermocouple

Aiming at the problems such as small tem perature measuring range,low reliability and slow response of ordinary thin film temperature sensor in gas turbine exhaust temperature measurement,this paper carri ed out research on high-temperature thin film therm ocouple technology,aiming to develop a fast response high-temperature redundant thin film thermocouple with excellent performance that can meet t he temperature measuring range of 0??1000?,response time is less than 2 seconds,high reliability of quick response to the high temperature redundant thin-film thermocouple,provide a new generation of high power gas turbine exhaust tempe rature detection means,to meet the requirements of gas turbine technology development.In this paper,a kind of high temperature redundant thin film thermocouple is designed and made to detect the exhaust temperature of gas turbine and study its performan ce.The main contents of this paper are as follows:Firstly,based on Seebeck effect of thin film thermocouple,the source and generating process of thermoelectric potential in thermocouple circuit are discussed.Based on the principle of thin film electr on transport and the size effect,the formula for calculating the conductivity of thin film is derived theoretically.The redundancy reliability theory of the thin film thermocouple is put forward,the mathematical model of the reliability of the high temperature thin film thermocouple is established by th e hypothesis test of the ordinary thin f ilm thermocouple,and the reliability calculation formula of the ordinary thin film thermocouple and the redundant thin film thermocouple is derived theoretically.T he results show that the reliability of the redunda nt thin film thermocouple is more and more close to 2 times that of the ordinary thin film thermocouple.Secondly,according to the design index of high temperature redundant film thermocouple,the structu re,size layout and mask design of high temperature redundant film thermocouple are completed.In this paper,the materials used in the components of the high temperature redundant film thermocouple are selected and matched in combination with the film preparation technology and the lead connection method to ensure that the high temperature redundant film thermocouple can work continuously and stably at high temperature.Then,using two-way flow heat and one-way thermal fluid-solid coupling simulation analysis method,finite element analysis for the desig n of thin-film thermocouple for the internal flow field of the sensor,the temperature field and structure field,high temperature redundant thin-film thermocouple work simulation test shows that the response time of the designed thin film thermocouple is less than 2 seconds,and the s tress and deformation are within the required range under operating temperature load and wind load.Finally,the fabrication technology of high temperature redundant thin film thermocouple was put forward,and the film thermocouple was prepared by film sputtering deposition,photolithography,ion beam etching and lead wire,and the performance of the sample was researched.The results showed that the output elec tromotive force of the platinum-rhodium 10-platinum thin film thermocouple at 0?1000? was almost equal to that of the standard s-type thermocouple,the maxi mum indexing error was 5.919%,the minimum indexing error was 0.114%,and the repeatability was about 99.47%,meeting the requirements of the verification regulation.Within 0?1000? temperature range,the stability of the thin-film thermocouple and can satisfy the use requirement.